Microbiology with Diseases by Taxonomy Chapter 22 Answers

Microbiology with Diseases by Taxonomy Chapter 22 Answers

Microbiology with Diseases by Taxonomy Answers

Microbiology with Diseases by Taxonomy Chapter 22 Answers 1CM
Following concept map describes systemic mycoses.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 1CT
The fungi and the spores produced by them are present almost everywhere in the environment- air, water, soil and on or in most of the multicellular organisms. However, their omnipresence due not cause diseases in human beings, though most of human beings experience mycosis at least once in life time. Fungi are so omnipresent that environmental contact to opportunistic fungal pathogens is not avertible.
Opportunistic fungi are present everywhere, but they lack the genes for virulence and cannot infect health individuals. The fungi exist as harmless residents in the environment.
However, the opportunistic pathogens attack and cause people with compromised immunity.
Many of the fungal pathogen enter through the same portals and lead to similar symptoms. This leads to difficulty in diagnosis. Diagnosis on the fungal infections only based on clinical symptoms is not recommended as some of the symptoms are very common among the fungal infections. Hence the detection of fungal pathogens is relied upon the following methods:

1. Direct microscopic examination of fresh specimens
2. Confirmatory isolation on solid media
3. Serological tests for host antibody

The ubiquitous nature of the fungi makes it difficult to control. And since majority of the fungi present more or less similar kind of clinical symptoms the diagnosis of fungal infections is also challenging.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 1FB
Dimorphic fungi exist in two forms:
The fungal species are existed in different types of environments and different types of physical forms. Here, the dimorphic fungi is shows the dimorphism on physical structure based on the temperature difference in their living conditions.
(a) In the environment where the temperature is below 30⁰C, this fungi grows as mycelial form composed of hyphae.
(b) In the human hosts where the temperature is at 37⁰C it grows as spherical yeast forms.
mycelial forms , yeast forms.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 1M
Please find below the correct options for the diseases with the manner in which fungi enter the body.
A. Inhalation:
The fungi enter the body through the respiratory tract via inhalation. A large number of fungi are inhaled on a daily basis by everyone. Microorganisms that attack the typical healthy respiratory tract have established specific mechanisms to avoid destruction by alveolar macrophages and to overcome muco-ciliary defenses. Following are the examples of the fungi that invade the body via inhalation. Hence the correct option is A) Aspergillosis, Coccidioidomycosis, Cryptococcosis, Histoplasmosis
B. Contact:
The fungi enter the body through the skin via dermal contact. Majority of microorganisms penetrate through breaks in the skin, which could be through superficial pricks, burns, wounds, and diabetic and pressure related foot infections. Following are the examples of the fungi that invade the body via inhalation. Hence the correct option is B) Candidiasis
C. Trauma:
The fungus is introduced directly into the host blood stream through mechanical injury or accidental injury. Trauma plays a significant role in causing fungal infection. Fungal pathogens introduced through trauma gains entry and launch themselves in the cornified layers of macerated or traumatized skin. Hence the correct option is C) Chromoblastomycosis, Dermatophycosis, Mycetoma, Sporotrichosis
D. Ingestion:
The fungus is introduced through the digestive tract via ingestion. Ingestion can occur via smoking or eating with contaminated hands or in unhygienic work areas. Hence the correct option is D) Hypersensitivity reactions, Mushroom poisoning

Microbiology with Diseases by Taxonomy Chapter 22 Answers 1MC
A fungus that can infect or causes disease in both healthy and immunocompromised patients is known as a true pathogen.
a. True pathogen:
True pathogen infects or causes disease in healthy individuals, irrespective of the immune status. True pathogenic fungi include Histoplasma capsulatum, Coccidioides immitis, Blastomyces dermatitidis, and Paracoccidiodies brasiliensis. Hence, this option is correct.
b. An opportunistic pathogen:
Opportunistic fungi on the other hand lack genes for proteins that help in colonizing body tissues, and therefore these fungi infect individuals with compromised immune system. Opportunistic fungi include Candida albicans and Pneumocystis Pneumonia. Hence, this option is incorrect.
c. A commensal organism:
A commensal organism lives in association within or on the other organism. Commensalism is a relationship in which one organism is benefited without causing any effect to the other organism. Hence, this option is incorrect.
d. A symbiotic organism:
A symbiotic organism lives in a close and prolonged association of a different organism belonging to same or a different species. In this association the organisms does not necessarily benefit each other. Hence, this option is incorrect.
Hence, the correct option is (a) a true pathogen is the fungus that is capable of infecting both immunocompetent and immune comprised individuals.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 1MTF
Fungi along with the spores they produce are Omni-present. They are found in the atmosphere, in soil, and in water. The fungal infections are acquired through inhalation, trauma, or ingestion. The fungal infections are generally not contagious. Epidemics of fungal infection do occur due to mass exposure to the environmental source of fungi, but not as result of transmitting from person to person.
Very rarely the fungi spread from one person to another. Dermatophytes are the group of fungi which are contagious.
Hence, the given statement, fungi are generally not transmitted from person to person is TRUE.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 1SA
The majority of the antifungal fungal drugs are toxic to human cells, due to the similarities between fungal and human cells. Human cell membranes and fungal membranes both contain sterols. The sterols are act as primary membrane target for anti-fungal agents. The human cell membrane contains cholesterol as sterol molecule; the fungal membrane contains Ergosterol as sterol molecule. Hence, all the antifungal agents like amphotericin B specifically target the ergosterol in fungal cytoplasmic membranes.
The side effects of using long term anti-fungal agents include headache, gastrointestinal upset, anemia, rashes, and serious damage to liver and kidney.
Though “amphotericin B” is considered as gold standard among the antifungal agents and this drug have more side effects and toxicity to the human beings. Amphotericin is usually prescribed after other antifungal antibiotics failed to treat the symptoms. Therefore, amphotericin B is used only in the treatment of life-threatening fungal infections.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 2CT

• Certain true fungal pathogens exhibit dimorphism –
  • Mycelial form that grows in the environment
  • Yeast form that grows in the human host
• Dimorphism indicates that environmental cues are prompting changes in gene expression in fungal pathogens.
• The mycelium mostly lives in soil and contamination happens when the human host breathes in mycelial or conidia that transform into the yeast form within the host lung.
• This capability to shift between mycelial and yeast forms is vital for the establishment of the infection.
• Because dimorphism exhibited by the fungal pathogen is obligatory for its capability to cause infection, the biochemical routes and the genes accountable for activating this course could be the main emphasis to develop new antifungal agents, which could be more efficient and specific.
• Characterization of the genes being expressed in the pathogenic yeast phase ascertains functions crucial to pathogenesis that in turn may be targeted by chemical equivalents of their metabolic intermediates.
• The most prominent difference between mycelial and yeast forms is the cell wall polysaccharide. 1,3-ß-glucan is found in mycelia and 1,3-a-glucan is found in yeast forms.
• Either the conditions in the host cell or specific antifungal agents targeting the 1,3-a-glucan present in the yeast cell wall can be utilized as targets for designing new anti-fungal agents
• The antifungal agent can be designed effectively to target fungal pathogen in its active form within the host.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 2FB
True pathogen infects (or) causes disease in healthy individuals, irrespective of the immune status. True pathogenic fungi include Blastomyces dermatitidis, Coccidioides immitis, Histoplasma capsulatum, and Paracoccidiodies brasiliensis.
Blastomyces dermatitidis, Coccidioides immitis, Histoplasma capsulatum, and Paracoccidiodies brasiliensis.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 2MC
Tricophyton rubrum is the fungi where the mode of transmission is from person to person.
a. Blastomyces dermatitidis :
In humans, this fungus is transmitted via inhalation of the airborne fungal spores. These fungal spores in soil become airborne during the occupational and recreational activities and thereby get inhaled. Hence, this option is incorrect.
b. Coccidioides immitis infection is caused by inhalation of the fungal spores/particles. Hence, this option is incorrect.
c. Tricophyton rubrum is a dermatophyte and is commonly known as athletes’ foot, ringworm, or jock itch. It is transmitted from person to person through their skin. Hence, this option is correct.
d. Aspergillus fumigtus:
Aspergillus fumigatus belongs to genus Aspergillus, and is among the most common Aspergillus species to cause infection in individuals with compromised immune system. The transmission of fungal spores to the human host is through inhalation.
Hence, the correct option is (c) Tricophyton rubrum is the fungus that is generally spread from person to person.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 2MTF
Fungal infections are difficult to treat due to the following reasons:

1. Biochemical ability:
   Fungi generally possess the biochemical ability to resist T-cell mediated immune responses.
2. Biochemical similarity:
   The majority of the antifungal fungal drugs are toxic to human cells due to the similarities between fungal and human cells. Human cell membranes and fungal membranes both contain sterols, a primary membrane target for anti-fungal agents. The only difference seen in the composition of membrane is the presence of ergosterol in the fungal cell in place of cholesterol in human cells. However, cholesterol and ergosterol are not distinct enough to prevent the damage to human tissues. Hence, all the antifungal agents have some extent of side effect.

Hence, the given statement, on the whole, fungal infections are relatively easy to treat is FALSE..
On the whole, fungal infections are relatively DIFFICULT to treat.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 2SA
The superficial mycoses are generally confined to the outer layers of skin, nails, and hair, and do not attack living tissues. These superficial fungi are known as dermatophytes. Dermatophytes are capable of producing extracellular enzymes known as keratinizes, which are able to hydrolyze keratin. This has enabled the superficial mycoses to dwell on the outer layers.
The dermatophytes causing infections in humans have diverse natural sources and means of transmission:

• Anthropophilic – Related with humans. Transmission from one man to another via close contact or through polluted items.
• Zoophilic – Related with animals. Transmission to man via close contact with animals (cats, cows, dogs) or with polluted items.
• Geophilic – These fungi are generally found in the soil and are spread to man via direct exposure.

Since these sources of infection are very common and also since the superficial mycoses are limited to the outer layers it is very difficult to determine the exact source. The symptoms produced by the fungal pathogen are similar and cannot be differentiated based on the source. Identifying the exact species of dermatophyte and cause of infection are crucial for appropriate treatment of the patient and also control of the source.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 3CT

• Reducing fungal growth in and on foods can aid in reducing usage of fungal toxins.
• By means of utilizing fungicides in fields where crops are grown can decrease the extent of fungi growing alongside the crops and consequently reduce the extent of fungal spore contamination when the crops exist in the field.
  • Growth of fungal resistant variations of growing plants;
  • Control field contamination of fungi by planting crops;
  • Expending preservatives and fungicides against fungal growth;
• Washing with cleansers or detergents after crop, cooking or radiation can decrease fungal growth on foods during storage.
• All the above stated precautions can be applied worldwide, however toxic fungi with distinct geographic dispersals might require precise precautions bespoke to local conditions.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 3FB
The majority of the antifungal fungal drugs are toxic to human cells due to the similarities between fungal and human cells. Human cell membranes and fungal membranes both contain sterols, a primary membrane target for anti-fungal agents.
The only difference seen in the composition of membrane is the presence of ergosterol in the fungal cell in place of cholesterol in human cells. Hence, all the antifungal agents target the ergosterol in fungal cytoplasmic membranes. Hence, the correct answer is Ergosterol.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 3MC
Identification of true fungal pathogens should be done by various screening methods like Gomori methenamine silver (GMS), microscopic examination, and serological testing. The identification of true fungal pathogen cannot be done by clinical symptoms alone.
a. Growth at 25⁰C and 37⁰C to show dimorphism :
Culturing the sample on Sabouraud dextrose agar for observation of colonies, and microscopic examination of yeast cells, mycelia, or mold spores. Microscopic examination for identification dimorphic forms exhibiting growth at 25⁰c and 37⁰c. This technique aids in identification of true fungal pathogen. Hence, this option is incorrect.
b. GMS staining of infected tissues:
Gomori methenamine silver (GMS) staining on the tissue sections to stain fungal cells black. GMS staining is widely used for diagnosis of fungal infections. This technique is recommended for identification of true fungal pathogen. Hence, this option is incorrect.
c. Serological testing involves measuring antibody in the serum and identification of antigens in the blood, secretions or tissue by the way of various immune-chemical techniques. It is transmitted from person to person through their skin. This technique is widely used for the identification of true fungal pathogen. Hence, this option is incorrect.
d. Clinical symptoms alone :
Diagnosis on the fungal infections only based on clinical symptoms is not recommended as some of the symptoms are very common among the fungal infections. Appropriate diagnosis of the causative agent is first step to effectively treat fungal infections. Hence, this option is correct.
Hence, the correct option is (d) clinical symptoms alone is not used to detect and identify true fungal pathogens.
Accurate diagnosis of fungal agents involves:

1. Direct microscopic examination of fresh specimens
2. Confirmatory isolation on solid media
3. Serological tests for host antibody

Microbiology with Diseases by Taxonomy Chapter 22 Answers 3MTF
Dermatophytes are the fungi that transmit from person to person and thrive only on skin, nails, and hair. Dermatophytes use keratin as a source of their nutrition and therefore colonize only on dead tissue.
Systemic mycoses on the other hand are contracted from the environment. These fungi spread across different geographical locations and cause pulmonary infections when the spores are inhaled. Systemic mycoses have the ability to spread beyond the lungs.
Hence, the given statement, Dermatophytes are always contracted from the environment is FALSE.
SYSTEMIC MYCOSES are always contracted from the environment.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 3SA
Superficial fungal infections are difficult to diagnose, and are often mistaken for other disorders, such as psoriasis or eczema. Fungal infections are usually analyzed on the basis of clinical appearance. Nevertheless, the antifungal or steroid reaction of a dermatosis may be utilized in the diagnosis, so it is significant that suitable investigations are initiated before administering any form of treatment, which often comprises an anti-fungal or a steroid cream. This approach will permit the diagnosis to be reevaluated if preliminary treatment is ineffective.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 4CT

• The blood supply is not direct to the nail beds, thus attributing to its slow growth rate.
• No direct blood supply also substantiates the fact that antifungal agents reach very slowly/or sluggishly to the nail beds and thus need a continuous level of medication over an extended period of time.
• Treatment over an extended period the will allow the antifungal agent to infiltrate to the site of the infection.
• Hence owing to the poor blood supply to the nail beds, Onychomycoses are both difficult to treat, and are generally require treatment with oral antifungal agents for long periods of time.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 4FB
Black piedra forms hard, black nodules, while white piedra produces soft, gray to white nodules.
Piedra is a characteristic hairy fungal disease is also called trichsporosis. The black piedra is caused by the single fungal species called Piedraia hortae.
The white piedra is caused due to the infection by several fungi, the nodules contains anthroconidia and yeast cells and hairy shafts. Hence, the correct answer is BLACK ,WHITE.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 4MC
Though amphotericin B is gold standard for treating fungal infections, it is extremely toxic to humans and most clinicians. Therefore, it is prescribed only for systemic infections.
a. Dermatophyte infections:
Dermatophyte infections are caused due to the fungus that infects skin, nails, and hair. These fungi have the ability to obtain required nutrients from the keratin. Majority of the infections are treated with topical application of the antifungal agents. Depending of the fungi causing the infection and severity, oral treatment will include itraconizole, terbinafine, or griseofulvin. Hence, this option is incorrect.
b. Malassezia infections:
Malassezia infections are naturally occuring on the skin surfaces of humans and animals. Melassazia infections are treated with ketoconazole or selenium disulfide containing shampoos. Other treatments include miconazole, coal tar, zinc pyrithione (ZPT), tea tree oil, or ciclopirox olamine medicated shampoos. Hence, this option is incorrect.
c. Systemic infections:
A systemic disease affects a number of tissues and organs, or infects the body as a whole via infection in the blood stream. Amphotericin B is the gold standard for treatment of systemic infections. Though it is toxic for human cells, in case of systemic infections where the intensity of the infection is severe, it is prescribed as the treatment option. Hence, this option is correct.
d. Black piedra:
Black piedra is fungal hair infection where soft black nodules form on hair shafts. Terbinafine is the antifungal agent used for treating black piedra. Hence, this option is incorrect.
Hence, the correct option is (c) systemic infections are treated with amphotericin B, though it is extremely toxic to humans.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 4MTF
Chromoblastomycosis and Phaeohyphomycosis are cutaneous and subcutaneous mycoses that look similar and are caused by dark-pigmented ascomycetes. Both the infections are caused due to traumatic introduction of the fungi into the skin. Lesions produced due to this infection may be far-reaching and can spread internally.
Hence, the given statement, Chromoblastomycosis and Phaeohyphomycosis are both caused by dark-pigmented ascomycetes is true.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 4SA
The fungi and fungal spores are present almost everywhere in the environment- air, water, soil and on or in most of the multicellular organisms. However, their omnipresence doses not always cause the diseases to human beings, some fungal species are have beneficiary effects.
Majority of the fungal infections are not contagious and hence do not spread from one infected person to another. Opportunistic fungi are present everywhere, but they lack the genes for virulence and cannot infect health individuals. The fungi exist as harmless residents in the environment.
The Opportunistic fungi like Aspergillus, Candida, Cryptococcus, pneumocystis, Mucor.
These fungal organisms associated with the other pathogenic infections like viral, increases the rate of disease condition.
However, the opportunistic pathogens attack and cause people with compromised immunity. In AIDS patients the immunity is at very low level. Hence, they become very good targets for the opportunistic pathogens to thrive on. The clinical manifestations of these fungi in AIDS patients are odd and pose challenge for the physicians to treat them. With the growing number of AID patients, opportunistic fungal infections have become significant cause of human disease and death.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 5CT
Following are the factors that contribute to the pathogenicity of Cryptococcus infections:
(a) Polysaccharide capsule:
Provide a poorly immunogenic surface and protect the bacteria from antibodies and phagocytosis. The polysaccharide capsule contains mannose, glucuronic acid, and sugar molecules with O-acetyl side chains.
The presence of polysaccharide layer on the bacterial surface provides the gelatinous nature, this nature help to pathogen to escape from the phagocytic cells. These carbohydrate molecules act as great virulence factors.
(b) Ability to produce melanin:
The ability of the yeast to produce melanin it is a pigment molecule, which further prevents phagocytosis. These species weakens the central nervous system.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 5FB
Sporotrichosis is caused by dimorphic ascomycete Sporothrix schenckii, which is commonly known as rose-garderner’s disease. Sporotrichosis is a sub cutaneous infection that is limited to arms and legs and it occurs mostly via thorn pricks and wood splinters.
The Sporotrichosis mainly attacks the skin (sub cutaneous), lungs (pulmonary) and joint bones.
This disease mainly affects the people, who worked near the gardens and farms, and they mostly grow in immune compromised individuals. Hence, the correct answer is SPOROTHRIX SCHENCKII.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 5MC
Ringworm is a superficial fungal infection caused by dermatophyte.
a. Helminth:
Helminths are parasitic worms that cause a range of transmittable diseases. The infections caused by helminth parasites include Elephantiasis, Bilharzia, Ascariasis, Trichuriasis, and hook worm. Hence, this option is incorrect.
b. Dermatophyte:
Ringworm or dermatophytosis is a fungal infection of the skin in humans, domesticated animals such as sheep, cattle, and pets such as cats. Ring worm is caused by a dermatophyte. Hence, this option is correct.
c. Dimorphic fungus:
Dimorphic fungi have the ability to exist as hyphal or filamentous form and yeast forms. Infections caused by dimorphic fungi include coccidioidomycosis, paracoccidioidomycosis, candidiasis, and blastomycosis. Hence, this option is incorrect.
d. Commensal fungus:
Commensal fungi are the group of fungi, which neither benefit nor harm to the host. Commensal fungi do not generally cause any infections. Hence, this option is incorrect.
Hence, the correct option is (b) dermatophyte is the causative agent of ring worm.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 5MTF
Sporotrichosis, commonly known as rose gardener’s disease is a sub cutaneous infection that is restricted to arms and legs. This fungus resides in solid and contracts humans by means of wood splinters or thorn pricks.
Hence, the given statement, Sporotrichosis is always caused by traumatic introduction of fungi beneath the skin is true.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 5SA
Following is the differentiation between mycotoxicosis and mycetismus.
(a) Mycotoxicosis:
Mycotoxins are toxins produced by fungi. Mycotoxicosis is caused by consuming mycotoxins; the fungus itself is not present in this case.
The Mycotoxins are chemical molecule they are poisonous in nature. Some, examples of Mycotoxins include Aflatoxins, which are produced by the Aspergillus species and ergot alkaloids synthesized by the Claviceps species.
(b) Mycetismus:
Mycetismus is a specific type of mycotoxicosis, caused by consuming the fungus. Mycetismus is commonly known as mushroom poisoning and is caused due to ingestion of toxic mushrooms. The deadliest mushroom toxin is produced by Amanita phalloides.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 6CT
Though subcutaneous mycoses cause lesions around the skin at the site of inoculation, following are some characteristics that will help in in distinguishing one kind of sub cutaneous fungi from another:

• Differentiated by the presence of pigments golden brown are developed by Fonsecaea while brown pigments are caused due to Cladophiolaphora.
• Differentiated by exhibiting dimorphic forms, whether it exists in the form is yeast (e.g. Sporothrix) or myeclial forms (Madurella and Pseudoallescheria).
• Differentiated by geographic location, region in which the infection was developed can also be beneficial in determining the causative agent.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 6FB
Cryptococcus neoformans is the primary species causing crytococcoses. Humans are infected via inhalation of spores (or) dried yeast aerosols from the droppings of the birds.
Hence, the correct answer is Cryptococcus neoformans.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 6MC
Aspergillus niger exhibits characteristic of opportunistic fungi and hence is a typical example of opportunistic fungus
a. Piedraia hortae :
Piedraia hortae is superficial mycoses, which causes black piedra. Piedraia hortae is found in Southeast Asia and throughout Central America. The infection caused is restricted to the superficial surfaces of the hair and skin. These infections are non-destructive and of cosmetic significance only. Hence, this option is incorrect.
b. Histoplasma capsulatum :
Histoplasma capsulatum is an ascomycete and causative agent of histoplamosis. Histoplasma capsulatum is classified as a true fungal pathogen, which means that it is capable of infecting immune competent individuals. Hence, this option is incorrect.
c. Fonsecaea pedrosoi :
Fonsecaea pedrosoi is the causative agent of the disease chromoblastomycosis. The mode of infection is through traumatic introduction of the fungi under the skin, usually by splinters or thorns. Though this fungus is prevalent across all regions, the occurrence of this disease is very low. Hence, this option is incorrect.
d. Aspergillus niger :
Aspergillus niger spores are found almost everywhere and human beings are routinely and constantly exposed to them. This kind of exposure is a normal part of the human condition and in general does not cause any adverse health effects. But, under favorable conditions like immune-comprised individuals, it can lead to systemic diseases. Aspergillus niger is less probable to cause human disease than some other Aspergillus species. But, in case of inhalation, large amounts of spores it can turn detrimental. Hence, this option is correct.
Hence, the correct option is (d) Aspergillus niger which has the characteristics of classical opportunistic fungus.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 6MTF
Coccidioidomycosis is caused by Ascomycete Cocidioides immitis, which is found exclusively in the country southwestern United States (Nevada, Texas, Arizona, New Mexico, and California) and also in Mexico. Few other regions where Cocidioides immitis is found include Central and South America.
Therefore, the possibility of Coccidioidomycosis occurring beyond the Western Hemisphere is limited.
Hence, the given statement Coccidioidomycosis does not occur normally outside the Western Hemisphere is TRUE.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 6SA
A. General area where Blastomycosis is endemic

B. General area where Coccidiodomycosis is endemic

C. General area where Histoplasmosis is endemic

Microbiology with Diseases by Taxonomy Chapter 22 Answers 7CT

• Health care providers have restricted possibilities to attempt to slow the increasing incidence of opportunistic fungal infections because of the omni-present nature of fungi and the difficulty in reducing the rate of increase of immunocompromised individuals.
• Adapting stringent hygienic techniques can lessen the occurrence of fungi and spores.
• Following some measures like filtration of air supplies in hospitals can reduce incidence of fungal infections.
• Restricted prescription of immunosuppressive medications in the treatment can lessen patient susceptibility.
• Using the least invasive procedural option can reduce nosocomial fungal infections that can be caused due to open surgeries.
• Educating patients about sources and threats of infection may also aid in prevention of certain infections.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 7FB
Opportunistic fungi lack genes for proteins that help in colonizing body tissues; therefore these fungi infect individuals with compromised immune system. Opportunistic fungi include:
The Candida, Aspergillus, Cryptococcus, Pneumocystis and Mucor .

Microbiology with Diseases by Taxonomy Chapter 22 Answers 7MC
Subcutaneous infections are contracted through trauma and these infections remain localized.
a. Inhalation and remain localized:
Systemic mycoses caused by opportunistic fungi are caused due to inhalation. The infections resulting from this group of fungi remain localized. Examples include aspergillosis and candidiasis. Hence, this option is incorrect.
b. Inhalation and become systemic:
Systemic mycoses caused by opportunistic fungi are acquired through inhalation. These infections start as general pulmonary infection that then spreads throughout the body via blood. Examples include histoplasmosis and blastomycosis. Hence, this option is incorrect.
c. Trauma and remain localized:
Subcutaneous mycoses are common soil saprobes living on dead organisms. But the infections produced by them are not as common as superficial mycoses since contamination requires traumatic introduction of fungi via the dead outer strata of skin into the deeper living tissue. Examples include chromoblastomycosis and phaeohyphomycosismycosis. Hence, this option is correct.
d. Trauma and become systemic:
Mycetoma is caused by filamentous fungi that attack traumatized skin. Lesions appear as blisters. The systemic form spreads to muscles and bones. Hence, this option is incorrect.
Hence, the correct option is (c) trauma and remain localized is applicable to subcutaneous infections.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 7MTF
The most common antibacterial drugs, their mode of action is to inhibit cell wall synthesis and repair. The anti-bacterial drugs derived from penicillin G, are broad-spectrum drugs that target both gram-negative and gram-positive bacteria.
Apart from the cell wall synthesis inhibition, some drugs have effect on the DNA synthesis, metabolic process and protein synthesis. The few examples of antibacterial drugs include rifamycin, sulfonamide, aminoglycosides, and tetracycline antibiotics.
The broad-spectrum antibacterial drugs have relatively low toxicity to humans because they target only the bacterial cell wall.
Hence, the given statement ‘’treatment of individuals with broad-spectrum antibacterial agents is a predisposing factor for opportunistic fungal infections” is TRUE.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 8FB
Oral candidiasis (or) thrush is caused by Candida. This infection is seen occurring amongst the immuno-compromised individuals. Hence, the genus causing thrush is CANDIDA.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 8MC
The term “dermatophyte,” refers to the fungal pathogen that grows in or on the skin. The term is indicative of the location on which the fungus thrives.
a. Pathogenicity:
Pathogenicity refers to the potential capability of certain species of fungal or microbial species to cause an infection or disease. Hence, this option is incorrect.
b. Where a fungus grows:
The term “dermatophyte,” which refers to the fungal organism that nurtures in or on the skin. The term is indicative of the location on which the fungus thrives. Hence, this option is correct.
c. Method of spread:
Method of spread indicates the mode in the spread of the infection, for example, from person to person, through environment, through aerosol, etc. Hence, this option is incorrect.
d. Pigmentation:
Pigmentation refers to the discoloration of the skin. It is caused due to fungal infections. Hence, this option is incorrect.
Since dermatophyte refers to the location or site on which the fungus grows, the correct option is (b) where a fungus grows.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 8MTF
Opportunistic fungi lack genes for proteins that help in colonizing body tissues, and therefore these fungi infect individuals with compromised immune system. Candida albicans is among the opportunistic fungi that can infect only individuals with compromised immune system.
The individual had a compromised immune system, because the person infected with the serious illness causing organisms like viruses. These viruses have the strong antigenic nature; they ultimately reduce the immunity level of the affected individual. Once the immunity level is reduced, the patient is susceptible of the other opportunistic infections.
Candida albicans generally causes localized opportunistic infections but can become systemic, particularly in the Imnuocompromised.
Hence, the given statement “Candida albicans generally causes localized opportunistic infections but can become systemic, particularly in the immunocompetent” is FLASE.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 9FB
Pneumocystis was formerly considered as a protozoan. Its morphological and developmental characteristic resembles those of a protozoan. However, based on rRNA sequence analysis and based on biochemical characters it has been now classified into fungus. The Pneumocystis is an opportunistic pathogen; it causes the diseases to an imnuo compromised individual.
Hence, the correct answer is Protozoan and Fungus.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 9MC
Subcutaneous mycoses that may demonstrate respiratory and cerebral forms is Phaeohyphomycosis.
a. Chromoblastomycosis:
infection occurs as small, scaly, itchy, and painless lesions of the surface of the skin due to fungal growth in subcutaneous tissues close to the location of inoculation. Hence, this option is incorrect.
b. Mycetoma:
causes infections on skin, fascia, and bones of hands or feet. It does not cause infections in respiratory tract and in cerebrum. Hence, this option is incorrect.
c. Phaeophyphomycosis:
colonizes in the nasal passages and sinuses in patients susceptible to allergies and in those suffering from AIDS. Phaeohyphomycosis can also cause brain infections in AIDS patients. Hence, this option is correct.
d. Sporotrichosis:
The infections caused by these fungi are limited to arms or legs. Hence, this option is incorrect.
Hence, the correct option is (c) Phaeohyphomycosis which is the subcutaneous mycoses that may possibly show respiratory and cerebral forms.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 9MTF
There are two categories of fungal agents:
True fungal pathogen:
True pathogen infects are causes disease in healthy individuals, irrespective of the immune status. True pathogenic fungi include Paracoccidiodies brasiliensis, Histoplasma capsulatum, Blastomyces dermatitidis, and Coccidioides immitis.
Opportunistic fungi:
Opportunistic fungi on the other hand lack genes for proteins that help in colonizing body tissues, and therefore these fungi infect individuals with compromised immune system. Opportunistic fungi include Candida albicans and Pneumocystis Pneumonia extra.
In AIDS patients the immunity of the patients is at very low level. These conditions are favorable for fungal infections; especially the opportunistic fungi. Therefore, AIDS patients generally are prone to and suffer from fungal infections. The first line of treatment for AIDS patients is through anti-fungal agents.
Hence, the given statement “relapse of fungal diseases is common in AIDS patients” is TRUE.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 10FB
The useful mycotoxins are classified as ergo alkaloids and these are produced by some strains of ascomycete Claviceps. Hence, the correct answer is Claviceps.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 10MC
Coccidiomycosis is the systemic mycosis that is found in the deserts of the southwestern United States.
a. Blastomycosis:
Blastomycosis infection is caused by ascomycete Blastomyces dermatidis, which is prevalent in southeastern United States north to Canada. This infection has also been reported from regions of Latin America, Africa, Asia, and Europe. Hence, this option is incorrect.
b. Coccidioidomycosis:
Coccidiomycosis is caused by Coccidiodes immitis found predominately in the southwestern United States (Arizona, California, Nevada, New Mexico, and Texas) and northern Mexico. Small, focally widespread areas also exist in semiarid parts of Central and South America. Coccidiomycosis can be recovered from desert soil, rodent burrows, archeological remains, and mines. Hence, this option is correct.
c. Histoplasmosis:
Histoplasmosis is caused by Histoplasma capsulatum. Histoplasma capsulatum is widespread in eastern United States along the Ohio River Valley and also seen in regions of Africa and South America. Hence, this option is incorrect.
d. Paracoccidioidomycosis:
Paracoccidiomycosis is caused by Paracoccidiodes brasiliensis found predominately in the damp and cool ranging from southern Mexico to regions of South America, especially in Brazil. Hence, this option is incorrect.
Hence, the correct option is (b) Coccidioidomycosis which is systemic mycoses that is widespread to the deserts of the southwestern United States.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 10MTF
Fungi and their spores are dispersed everywhere in the environment- in water, in air, in soil and on or in most multicellular organisms including animals and plants. However, fungal infections and allergies are not very common. Majority of the fungi being opportunistic, infect only immune compromised individuals and very rarely true pathogens cause infections. Not everyone is prone to allergies to fungal elements.
Hence, the given statement, almost everyone has allergies to fungal elements, is FALSE.
3 – 10% of individuals have allergies to fungal elements.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 11MC
a. Blastomyces dermatitidis:
B. dermatitidis is a dimorphic fungal pathogen, exhibiting filamentous and yeast forms. It survives in filamentous form in the soil, which produces spores directly on the wall of the hyphae. When inhaled the spores cause infection in humans and animals. At the elevated temperature of 37°C in a host, the spores transition to pathogenic yeast form. Hence, the option (a) is incorrect.
b. Histoplasma capsulatum:
Histoplasma capsulatum exhibits unique dimorphism and undergoes significant development stages depending on the temperature.

1. At 25°C, H. capsulatum exhibits a filamentous mycelia form.
2. At 37°C, H. capsulatum exhibits a yeast form.
   Hence, the option (c) is incorrect.

c. Paracoccidioides brasiliensis:
Paracoccidioides brasiliensis is thermally dimorphic fungus. At 25°C, exhibits filamentous form and at 37°C, transforms to yeast form. Hence, the option (d) is incorrect.
d. Coccidiodes immitis :
Coccidiodes immitis grows as mycelium and produces sturdy chains of asexual spores called arthroconidia. The arthroconidia germinate into new mycelia in the atmosphere. However, if inhaled arthroconidia germinate in the lungs to produce parasitic form called a spherule. Thus, spherule stage is parasitic form exhibited by Coccidiodes immitis when arthroconidia spores are inhaled. Hence, the correct option is (b) Coccidiodes immitis exhibits a spherule stage when it infects humans.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 12MC
a. Chromoblastomycosis:
Chromoblastomycosis is a chronic mycosis of skin and dermal tissue, initiated by traumatic introduction of a specific group of dermatophyte. For Chromoblastomycosis, fungus has been introduced into the individual by traumatic means. The infection is not specific to AIDS patients, but can be seen in any individual who happen to encounter the fungus. Hence, the option (a) is incorrect.
b. Blastomycosis :
B lastomyces dermatitidis is a causative agent for blastomycosis. The fungus lives in association with decomposing organic matter and damp soil. Infection is caused, due to inhalation of airborne, microscopic fungal spores. Blastomycosis is seen occurring in individuals who are otherwise healthy, but is more common among people with low levels of immunity. Individuals have to come in contact with the spores, and upon inhalation will contract blastomycosis. Hence, the option (b) is incorrect.
c. Piedra:
The source of infection in black piedra is from the soil. Moreover, white piedra exist in soil, air, water, vegetable matter, sputum, and body surfaces. Transmission is by way of shared hair brushes and combs. Piedra infections are caused due to opportunistic fungi, which are not commonly seen in AIDS patients. Hence, the option (d) is incorrect.
d. Candidiasis:
Candidiasis is infection or disease caused by various species of the genus Candida albicans, which is capable of infecting all the tissues. Moreover, Candida albicans is commensal and exists as normal gut flora living in human mouth and gastrointestinal tract. Candida albicans is truly an opportunistic fungus, as it infects nearly all the individuals as soon as the immunity of the host is compromised.
Following are some of the infections caused:

• Oral candidiasis is very rare in healthy individuals, but occurs at about 5% of the newborns.
• Candidiasis is seen in at least 10% of the adults with a weak immune system.
• Candidiasis affects nearly anyone suffering from AIDS.

Candida albicans exists as commensal where the host immunity is compromised and is turned into opportunistic pathogen. Candidiasis is seen in almost all terminal AIDS patients. Thus, candidiasis is the most commonly occurring fungal infection in nearly all the terminal AIDS patients.
Hence, the correct option is (c) Candidiasis is the fungal infection, which is seen in nearly all terminal AIDS patients.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 13MC
a. Invasive medical procedures:
Invasive medical procedures include surgery, insertion of medical implants, catheterization, etc. Surgical insertions introduce fungal spores and provide a site for fungal colonization. However, infections are avoided by following correct antisepsis and medical procedures by medical personnel. Hence, the option (a) is incorrect.
b. Chronic illness such as diabetes:
In case of chronic illness like diabetes the immunity of the patients is dysfunctional or compromised. Fungal infections in the cases can be avoided by taking proper medication to check the levels of sugar and keeping oneself free from injury. Hence, the option (c) is incorrect.
c. Short-term treatment with antibacterial agents:
Short term treatment with antibacterial agents will lead to infections, caused by opportunistic fungal pathogens. This can overcome by adopting complete and broad spectrum antibiotics. Hence, the option (d) is incorrect.
d. AIDS :
Opportunistic fungal infections infect individuals with low immunity levels. In AIDS (acquired immunodeficiency syndrome) patients the immunity is compromised and forms good basis for opportunistic fungi to attack. Even the commensal fungi like Candida cause infections to AIDS patients. Individuals infected with AIDS can face detrimental health threats from “opportunistic” fungal infections, which take the advantage of hosts’ compromised immune system. Moreover, person suffering from AIDS is likely to be infected by over 20 opportunistic infections. Therefore, AIDS is considered to be a predisposing factor for acquiring fungal infections. Thus, Patients suffering with AIDS are at high risk and invariably contract fungal diseases.
Hence, the correct option is (b) AIDS is a predisposing factor that leaves a patient with a maximum long-term risk of contracting a fungal infection.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 14MC
a. Type II hypersensitivity is referred as cytotoxic hypersensitivity. In type II hypersensitivity, antibodies produced by immune reaction bind to antigens on patient’s cell surfaces. Moreover, other form of type II hypersensitivity is known as antibody-dependent cell-mediated cytotoxicity (ADCC). Type II hypersensitivity mostly facilitated by antibodies of IgM or IgG classes. Thus, phagocytes and K cells play a role in ADCC. Hence, the option (b) is incorrect.
b. Type III hypersensitivity is referred as immune complex hypersensitivity. Type III hypersensitivity arises when antigen-antibody complex are not effectively cleared by accumulation of native immune cells, giving rise to an inflammatory reaction and desirability for leukocytes. The reaction may be pathogenic mechanism of infections caused by several microorganisms. Hence, the option is incorrect. Hence, the option (c) is incorrect.
c. Type IV hypersensitivity:
Type IV hypersensitivity is also known as delayed type hypersensitivity, as it takes two to three days for the reaction to develop. Unlike other types, type IV hypersensitivity is not antibody mediated but instead is a type of cell-mediated response. Very rarely, fungal allergens trigger type III hypersensitivities. Hence, the option (d) is incorrect.
d. Type I hypersensitivity:
Type I hypersensitivity is also known as immediate hypersensitivity. Type I hypersensitivity is an allergic reaction triggered by re-exposure to a specific type of antigen known as an allergen. Exposure to allergen may be by consumption, inhalation, inoculation, and direct contact. In type 1 hypersensitivity the antibody is IgE. Fungal allergens trigger type I hypersensitive reactions in which immunoglobulin E binds the allergens, stimulating reactions such as hay fever, asthma, eczema, etc. Thus, fungal allergens trigger type I hypersensitive reactions in which immunoglobulin E binds the allergens, stimulating reactions such as hay fever, asthma, eczema, etc.
Hence, the correct option is (a) type I hypersensitivity reactions is stimulated due to fungal allergens.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 15MC
a. Production of destructive enzymes:
Cryptococcus neoformans does not produce any destructive enzymes. The pathogenicity of Cryptococcus neoformans is due to the presence of capsule. Moreover, it has the ability to produce melanin and organism’s predilection for the central nervous system. Hence, the option (a) is incorrect.
b. Infection of immune cells:
Cryptococcus neoformans does not cause any infection to the immune cells. The pathogenicity of Cryptococcus neoformans is due to capsule, its ability to produce melanin and the organism’s predilection for the central nervous system. Hence, the option (c) is incorrect.
c. Variation of surface antigens to avoid immune system recognition:
The surface antigens are not present in Cryptococcus neoformans. The pathogenicity of Cryptococcus neoformans is due to capsule, its ability to produce melanin and the organism’s predilection for the central nervous system. Hence, the option (d) is incorrect.
d. Production of a capsule :
The pathogenesis of Cryptococcus neoformans is due to the following characteristics:

1. Presence of a phagocytosis-resistant capsule around the yeast form
2. Ability to produce melanin, which also aids in inhibiting phagocytosis
3. The organism’s predilection for the central nervous system

Hence, the correct option is (b) production of capsule attributed to the pathogenic feature of Cryptococcus neoformans.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 16MC
a. Blindness :
Cryptococcus infection in AIDS patients led to meningitis and cutaneous cryptococcosis. There is no evidence of blindness cause Cryptococcus infection in AIDS (acquired immunodeficiency) patients. Hence, the option (a) is incorrect.
b. Cutaneous infection :
Cryptococcus infection in AIDS patients led to meningitis and cutaneous cryptococcosis. However, meningitis is most commonly occurring as compared to cutaneous infection. Hence, the option (b) is incorrect.
c. Pneumonia :
Cryptococcus infection in AIDS patients led to meningitis and cutaneous cryptococcosis. There is no evidence of the pneumonia caused Cryptococcus infection in AIDs patients. Hence, the option (d) is incorrect.
d. Meningitis :
In AIDS patients the most common manifestation of Cryptococcus infection is meningitis. The second most common manifestation is cutaneous cryptococcosis.
Hence, the correct option is (c) meningitis is the most common occurrence of the Cryptococcus infection in AIDS patients.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 17MC
Aspergillosis is the name specified to varied range of infections, caused by infection of the genus Aspergillus. Aspergillosis progresses mainly in immunocompromised individuals. Hence, the option (a) is incorrect.
Dermatophytosis is also known as ringworm. It is caused by closely linked group of fungi, known as dermatophytes. Dermatophytes are fungi that cause infections in hair, skin, and nail due to their ability to utilize keratin, as a nutrient source. Hence, the option (b) is incorrect.
Mycetoma is a chronic subcutaneous infection caused by fungi and actinomycetes. This infection is an outcome of granulomatous inflammatory response in deep dermis and subcutaneous tissue. Moreover, it can be spread to underlying bone. Hence, the option (c) is incorrect.
Zygomycosis are opportunistic fungal infections, affected by genera of fungi classified in the division Zygomycota, especially Rhizopus or Absidia. Rhizopus is the classic bread mold causes Zygomycosis.
Hence, the correct option is (d) zygomycosis is caused by bread mold.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 18MC
Inhalation of fungal allergens:
Mycetismus is fungal poisoning, caused by consumption of certain species of mushrooms. The mode of infection in this case is due to ingestion and not due to inhalation of fungal allergens. Example of fungal infections, caused due to inhalation of Histoplasmosis and Coccidioidomycosis. Hence, the option (a) is incorrect.
Traumatic inoculation of fungi beneath the skin:
Mycetismus is fungal poisoning, caused by consumption of certain species of mushrooms. The mode of infection in this case is due to ingestion and not due to traumatic introduction of fungi beneath the skin. Example of fungal infection caused, due to inhalation of chromoblastomycosis. Hence, the option (c) is incorrect.
Close contact with infected individuals:
Mycetismus is fungal poisoning, caused by consumption of certain species of mushrooms. The mode of infection in this case is due to ingestion and is not contracted due to contact with infected individual. Example of fungal infection is caused due to close contact with infected individuals like, candidiasis and ringworm. Hence, the option (d) is incorrect.
Ingestion of mushrooms:
Mycetismus is caused by eating mycotoxic mushrooms. Mycetismus is fungal poisoning, caused by consumption of certain species of mushrooms (fungal organisms). It is also called as mushroom poisoning. However, in most cases occurs when untrained individuals pick and consume wild mushrooms.
Hence, the correct option is (b) ingestion of mushrooms is the mode of infection in mycetismus.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 19MC
Amanita muscaria, commonly known as the fly amanita or fly agaric, is a poisonous basidiomycete fungus. Moreover, Amanita muscaria produces two hallucinogenic toxins – ibotenic acid and muscimel. However, Amanita phalloides is most toxic fungus in comparison to Amanita muscaria. Hence, the option (b) is incorrect.
Psilocybe cubensis, commonly known as magic mushrooms, cubes golden tops, gold caps or boomers. Psilocybe cubensis produces hallucinogenic psilocybin. However, the toxin is not less toxic to phalloidin and alpha-amanitin produced by Amanita phalloides. Hence, the option (c) is incorrect.
Claviceps purpurea is an ergot fungus that nurtures on the ears of rye and related cereal crops. Claviceps purpurea produces mycotoxins that are considered beneficial. Hence, the option (d) is incorrect.
Amanita phalloides: The most deadly mushroom toxin is produced Amanita phalloides, which is commonly called as “death cap” mushroom. The mushroom contains two related polypeptide toxins:

1. Phalloidin, which disrupts the cell structure by binding irreversibly binding actin within cells
2. Alpha-amanitin, obstructs mRNA synthesis

Hence, the correct option is (a) Amanita phalloides which produces more poisonous mycotoxin.

Microbiology with Diseases by Taxonomy Chapter 22 Answers 20MC
The number of fungi in the environment is rising:
Fungi have a universal distribution, and breed in a wide range of habitats, including extreme climates. The fungi are present almost everywhere – atmosphere, water, soil, etc. Human beings are in contact with fungi in their day to day lives. However, the fungi are able to cause disease in individuals with compromised immune system. Increase in the number of mycoses cannot be justified to increase in the number of fungi in the environment. Hence, the option (a) is incorrect.
Fungi have become more pathogenic:
The pathogenic characteristics of fungi have evolved along the development of anti-fungal agents. Fungi have developed mechanisms to become resistance to anti-fungal agents. However, the advancement in medicine allowed treating the drug resistant fungi. Hence, the option (c) is incorrect.
Fungi are developing a tendency to be spread from person to person:
Majority of the fungi is opportunistic in nature. However, true fungal pathogens can infect healthy individuals. The fungal infections are majorly through ingestion, inoculation, and inhalation of the spores. Very few species of the fungi like dermatophytes have the tendency to spread from person to person. Hence, the option (d) is incorrect.
The number of immunocompromised individuals in the population is rising:
Opportunistic mycoses do not usually infect individuals with strong immune system, as the fungi lack genes for virulence factors to make them aggressively invasive. Moreover, opportunistic mycoses are restricted to individuals with compromised immune system. This is because of increase in the number of AIDS (acquired immunodeficiency syndrome) patients and number of mycoses worldwide cases that has been on rise.
Hence, the correct option is (b) the number of immunocompromised individuals in the population rising is the prime cause, for increase in number of mycoses worldwide.