Microbiology with Diseases by Taxonomy Chapter 20 Answers
Microbiology with Diseases by Taxonomy Answers
Microbiology with Diseases by Taxonomy Chapter 20 Answers 1CM
The following concept map describes completely about Escherichia coli. This includes the toxins liberated by the bacterium as well as about its transmission and the infection caused by it.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 1CT
The boy’s death could have resulted from meningitis, which is caused by Neisseria meningitidis. This bacterium is transmitted via droplets and spreads among people living in close contact, especially in dormitories, day cares, immediate family members etc. the symptoms of this disease include abrupt headache, sore throat, fever, vomiting, and convulsions. In this case, the boy has complained about sudden head ache and since he attends day care, which is a crowded place, there are more possibilities of contracting meningitis.
The day care workers are not to be blames for the boy’s death. Meningococcal meningitis progress very rapidly and may cause death within 6 hours of the initial symptoms. The day workers have alerted the boy’s mother at the appropriate time. The hospital staff is partially responsible for the boy’s death.
The boy has been the administration of penicillin, which might have triggered shock due to release of large amount of toxic lipid A resulting from killing many bacteria at a time. The options generally adopted for treating meningitis include intravenous administration of ceftriaxone and cephalosporin.
Following steps should be taken to protect the other children at the day care facility:
- Prophylactic treatment with ceftriaxone, ciprofloxacin, or rifampin for all children and workers at the day care.
- Vaccination for children above two years against the strains A, C and Y.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 1L
Microbiology with Diseases by Taxonomy Chapter 20 Answers 1M
Escherichia coli is the most common coli form that is most widely studied. E.Coli causes non-nosocomial urinary tract infections, fatal hemorrhagic colitis, gastroenteritis and hemolytic uremic syndrome. Hence the correct option is C) Gastroenteritis.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 1MC
Lipid A is among the common virulence factor to all genera within Enterobacteriaceae. Lipid A is specific to gram-negative bacteria and is present in cell wall. When released into patient’s blood it triggers vasodilation, shock, fever, blood clots throughout the body, and disseminated intravascular coagulation (DIC).
a) Affects the formation of blood clots in the host:
Lipid A which is specific to gram negative bacteria and is present in cell wall. When released into patient’s blood it triggers vasodilation, shock, fever, blood clots throughout the body, and disseminated intravascular coagulation (DIC). Hence, this option is correct.
b) Causes these bacteria to be oxidase positive:
Microorganisms that are oxidase positive are aerobic. The oxidase positive microorganisms are capable of utilizing oxygen as a terminal electron acceptor during respiration. Oxidase positive generally means that the bacterium contains cytochrome c oxidase and can hence utilize oxygen for energy production with an electron transfer chain. Hence, this option is incorrect.
c) Triggers the secretion of a protease enzyme to cleave IgA in mucus:
Viral DNA sequences in a patient’s blood or other tissues can be identified by genetic screening. Moreover, it can identify the disease even before the patient show any symptom. Hence, this option is incorrect.
d) Enables the bacteria to ferment glucose anaerobically:
The process of synthesizing a polypeptide chain from an RNA template is called as translation. After this, post-translational modifications take place to make the polypeptide chains into active proteins. Hence, this option is incorrect.
Hence, the correct option is a) genetic fingerprinting, which is the technique that involves the production of a distinct pattern of DNA fragments on a gel.
Hence, the correct choice is Lipid A present in outer membranes of Gram-negative bacteria affects the formation of blood clots throughout the body in the host.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 1SA
Antimicrobial drug is not prescribed to treat diarrhea patient:
Explanation
The treatment of Diarrhea comprises of treating the patient with electrolyte and fluids replacement. Since, diarrhea is self-limiting expulsion of the organism from the body. It is more effective on administering antimicrobial agents. Besides, treatment of diarrhea with antimicrobial agents can worsen the prognosis. However, results in killing many bacteria, which will lead to the release of large amounts of lipid A and turn toxic.
Hence, in this case the treatment prescribed by the physician in treating the patient with diarrhea is appropriate. Prescribing fluid replacement is a right measure. Thus, administering antimicrobial drugs will worsen the patient’s condition.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 2CT
One important reason for the better response of the gram-positive bacteria to that of gram-negative bacteria is the structure of the outer membrane. Below outlined are the differences observed:
Gram negative bacteria:
- Presence of outer membrane
- High lipopolysaccharide (LPS) content
- High lipid and lipoprotein content
- Single and thin peptidoglycan layer
- The cell wall is 70-120 Armstrong thick two layered
- Highly resistant to physical disruption, dyes, and drying
Gram positive bacteria:
- Absence of outer membrane
- Very little or no lipopolysaccharide (LPS) content
- Low lipid and lipoprotein content
- Multilayered peptidoglycan layer
- The cell wall is 100-120 Armstrong thick two layered
- Low resistance to physical disruption, dyes, and drying
Gram-negative bacteria are more resistant against antibodies than gram-positive bacteria, because of their impenetrable cell wall. The outer membrane of gram- negative bacteria protects it from several antibiotics, dyes, and detergents that would usually destruct the inner membrane or peptidoglycan. The outer membrane provides gram-negative bacteria resistance to penicillin and lysozyme.
Hence, the gram-positive bacteria respond to treatment of antimicrobial drugs and thereby the fatality rates in case of gram-positive bacteria are low.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 2M
Klebsiella pneumonia is the causative bacterium for pneumonia which often involves damage of alveoli and the producing of bloody sputum.
This bacterium mostly grows in the respiratory tracks and digestive system of the humans and some animals. It is also associated with the several diseases like urinary tract infections and wound infections. Hence, the correct option is F) Pneumonia.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 2MC
The only genus of Gram-negative cocci that causes significant disease in humans is Neisseria.
(a) Pasteurella :
It is a nonmotile, Gram-negative coccobacillus. It causes zoonotic infections in humans. It causes significant diseases in animals. Hence, this option is incorrect.
(b) Salmonella :
It is a genus consisting of motile, Gram-negative bacilli. Hence, this option is incorrect.
(c) Klebsiella :
It is a nonmotile, Gram-negative coccobacillus. It is usually present in the respiratory tract of humans. The common disease that it causes is pneumonia. Hence, this option is incorrect.
(d) Neisseria :
It is a pathogenic Gram-negative coccus. It regularly causes disease in humans. The significant diseases that it causes in humans are gonorrhea and meningitis. Hence, this option is correct.
Hence, the correct option is (d) Neisseria. The only genus of Gram-negative cocci that causes significant diseases in humans is Neisseria.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 2SA
Distinction between pathogenicity of coliforms, non-coliforms, and pathogenic enteric bacteria:
Explanation
Pathogenicity of enterobacteriaceae:
Lipooligosaccharides:
Composed of three antigens- a core polysaccharide called the common antigen, O-polysaccharide, and Lipid A, which trigger vasodilation, fever, and other symptoms when released into the blood.
Fimbriae:
Fimbriae along with proteins are called adhesins, which enable the bacteria to attach themselves to the human cells.
Polysaccharide capsule:
Provide poorly immunogenic surface and protect the bacteria from antibodies and phagocytosis.
Siderophores:
Capture iron and make it available to the bacteria.
Hemolysins:
Lyse red blood cells by releasing nutrients such as iron.
Exotoxins:
Cause a variety of symptoms, such as diarrhea.
Type III secretion system:
The complex structure is composed of 20 different polypeptides, synthesized by several pathogenic enteric species.
- Coliforms: Coliforms are defined as facultative anaerobic or aerobic, rod shaped, Gram-negative bacteria, and ferment lactose. The most common coli form pathogens are Serratia, Escherichia, Klebsiella,Hafni, Enterobacter, and Citrobacter.
Pathogenicity:- Fimbriae along with proteins called adhesins enable the bacteria to attach themselves to the human cells.
- Exotoxins: Cause a variety of symptoms such as diarrhea.
- Non-coliforms: Non-coliforms are opportunistic pathogens that ferment lactose. Noncoli form opportunists include Proteus, Morganella, Providencia, and Edwarsiella.
Pathogenicity:- They produce IgA-degrading protease, which functions to cleave secretory IgA, which is released by host in an initial response to infection.
- Non coli forms produce three unique flagellin genes, which recombine and form novel flagella adept of deceiving the host’s defenses.
- These forms produce fimbriae along with proteins called adhesins enable the bacteria to attach themselves to the human cells.
- Another mechanism is the urease-mediated stone formation. Urease and hemolysin damage the host epithelial cells.
- Truly pathogenic enteric bacteria: These are non-lactose-fermenting bacteria and include three important pathogens – Salmonella, Shigella, and Yersinia.
Pathogenicity:- These bacteria synthesize type III secretion systems by which they introduce proteins to rearrange the cytoskeletons of eukaryotic cells, induce apoptosis or inhibit phagocytosis.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 3CT
Based on the characteristics and biochemical test result, the causative agent is Shigella dysenteriae. This is non-motile, Gram-negative, urease negative, lactose negative and does not produce hydrogen sulfide gas. This bacterium produces a diarrhea inducing enterotoxin, and causes severe dysentery called shigellosis. Shigella dysenteriae can spread from person-to-person; especially it spreads very quickly among children and homosexual men.
Children can be infected by consuming ingesting bacterium through contaminated hands and also by in taking of infected food. Due to the tendency of this species to spread from person to person, it can easily contract other children in the vicinity of the infected individual or child.
The official should increase the hygiene in the community and follow effective procedures for sewage treatment. The officials can also treat the children in the community with oral antimicrobial drugs such as ciproflaxin, cephalosporin, etc., to inhibit the spread of the Shigella to close contacts of the patient.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 3M
Proteus mirabilis is associated with urinary tract infections in patients. This microorganism, releases a large amount urease in the bladder, which cause the breakdown of urea into ammonia and carbon dioxide.
Thus produced ammonia increase the pH levels of urine in the bladder and in the kidney, such that ions that are normally soluble at the acidic pH of urine will start to precipitate. These precipitations are formed around the bacterial cells to form infection induced kidney stones composed of calcium phosphate (or) magnesium ammonium phosphate. Hence the correct option is D) Kidney stones.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 3MC
The bacterial cell having fimbriae, lipooligosaccharide and polysaccharide will be more virulent. Absence of any one of these will result in the decrement of its virulence.
(a) A cell with fimbriae and LOS:
The cell with fimbriae and lipoooligosaccharide will be virulent. Fimbriae help the bacteria to attach to the human cell. LOS displays antigenic diversity, which aids in the evasion of the host defense mechanism. Even though, there will be a chance of being targeted by the host defense mechanism due to the absence of the other virulent factor, polysaccharide. Hence, this option is incorrect.
(b) A cell with a polysaccharide capsule and lipooligosaccharide:
Polysaccharide capsule protects the bacteria from phagocytosis and antibodies. Lipooligosaccharide displays antigenic diversity. These will be helpful in evading host’s immune system. But to cause infection, the bacteria have to attach to the host cell. It is possible by the help of fimbriae, which are absent in this cell. Hence, this option is incorrect.
(c) A cell with fimbriae, lipooligosacchride and a polysaccharide capsule:
Fimbriae enable the bacteria to attach to the human cell. Lipooligosaccharide will display antigenic diversity. Polysaccharide capsule will protect the bacteria from phagocytosis and antibodies. This cell will be more capable in evading the host immune system. Hence, this option is correct.
(d) A cell with fimbriae but no capsule:
Fimbriae will help the cell to attach to the host cell. But due to the absence of capsule, this cell will be either phagocytized or will be attacked by the antibodies. Thus, this cell may be non-virulent. Hence, this option is incorrect.
Hence, the correct option is (c) a cell with fimbriae, lipooligosaccharide and a polysaccharide capsule. A bacterial cell with fimbriae, lipooligosaccharide and a polysaccharide capsule is most likely to be virulent.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 3SA
Antimicrobial agents are placed in eyes of babies, during birth:
Explanation
The treatment of Neisseria gonorrhea is complicated, due to the worldwide spread of gonococcal strains. Moreover, the strains are resistant to antibacterial treatments like penicillin, erythromycin, and aminoglycosides. Besides, chemical prophylaxis is ineffective in preventing Neisseria gonorrhea. Therefore, nurses place antimicrobial agents in the babies’ eyes at birth, as a prophylactic measure that successfully prevents ophthalmic disease.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 4CT
Majority of the cases reporting typhoid fever are associated with international travel. The risk of contamination is maximum for international travelers visiting families and friends in nations where typhoid fever is endemic, perhaps because they are unlikely than other travelers to seek pre-travel immunization and to observe safe drinking water and food practices.
Several years ago, the international travels and vacations were more in number during summer. This attributed to more number of typhoid cases during summers. However, the frequency of travel due to opening of trade and relations between many countries has increased drastically. The risk is higher for travelers who visit the most highly endemic areas, even for a shorter term. Hence, the numbers of cases with typhoid fever are being observed throughout the year.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 4M
Salmonella enterica, it comes under the serotype Typhi (S. typhi). This bacterium mainly causes fever known as typhoid. Human beings are the sole hosts for this microorganism. Infection occurs through intake of contaminated food (or) water contaminated with sewage containing bacteria from carriers. These carriers are often asymptomatic.
This bacterium once enters into the intestine reach to the blood stream; they are opsonized by the phagocytic cells, but not killed by them. These phagocytic cells carry bacterium into various organs like liver, spleen, and bone marrow extra.
After, they enter into these organs they effect on their regular functions and show several disease symptoms like fever, and loss of appetite. Hence, the correct option is B) Typhoid fever.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 4MC
Pelvic inflammatory disease (PID) is caused by Neisseria gonorrhoeae.
(a) PID is a severe type of diarrhea in which infection spreads from the intestines to the bloodstream:
PID is a sexually transmitted disease. It infects the uterus and uterine tubes. It is not diarrhea. Hence, this option is incorrect.
(b) PID can result from Neisseria infection:
PID is caused by Neisseria gonorrhoeae. It is a sexually transmitted disease. Hence, this option is correct.
(c) PID is more common in men than women:
PID is a sexually transmitted disease. It infects the uterus and uterine tubes and thus commonly occurs in women. Hence, this option is incorrect.
(d) Members of the family Enterobacteriaceae usually causes PID:
PID is sexually transmitted disease caused by Neisseria. Members of the family Enterobacteriaceae are neither sexually transmitted nor causes PID. Hence, this option is incorrect.
Hence, the correct option is (b) PID can result from Neisseria infection. The statement that PID can result from Neisseria infection is true.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 4SA
Meningococcal diseases are more frequent in college dormitories and military barracks when compared to population:
Explanation
The meningococcal infection is transmitted through respiratory droplets that transmit among people who live in close contact. The transmission is widespread among families, soldiers living in barracks, prisoners, and college students living in dormitories. This is because the groups of people live in crowded conditions. Therefore, statistics indicate that meningococcal disease is 23 times more prevalent in students living in dormitories, as compared to cases in general population.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 5CT
Stomach flu in fact refers to gastroenteritis or inflammation and irritation of the stomach and intestines. Gastroenteritis may be triggered by a virus, bacteria, parasites, or due to lactose intolerance. The symptoms of stomach flu or gastroenteritis include abdominal cramps, stomach pain, nausea, and diarrhea.
Following is the list of bacteria discussed in this chapter, which are good candidates for causing stomach flu:
- Escherichia coli infection can cause significant problems. E. coli O157:H7 can cause complications in nearly 10% of infected individuals, for example, kidney failure in children (hemolytic-uremic syndrome), thrombotic thrombocytopenic purpura (TTP) in the adults and bloody diarrhea.
- Salmonella is contracted by ingestion of bacteria present in contaminated water or food, and by handling reptiles or poultry that transmit the germs.
- Shigella generally spreads from one person to another. Shigella may be contracted by ingestion of contaminated food, and drinking water, or playing or swimming in contaminated water.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 5M
Shigella flexineri are a group of bacteria that can causes dysentery. Shigella flexineri causes severe form of dysentery which is characterized by fever, diarrhea, purulent bloody stools and cramps.
Once, the Shigella is enters into the gastrointestinal tract it attaches to the Epithelial cells of colon. It triggers the process of endocytosis, enters into the epithelial cells. Than bacterium multiplies in the cytosol of epithelial cells, it invades into neighboring cells. Ultimately, they are enters into the blood stream. Leads to abnormalities on immune system, this result diseases. Hence, the correct option is E) Purulent bloody stools, cramps, fever, and diarrhea.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 5MC
The coliform bacterium that contaminates dairy products is Enterobacter.
(a) Bartonella :
It causes Bartonellosis in humans. It is transmitted by very small blood sucking sandflies. It doesn’t contaminate dairy products. Hence, this option is incorrect.
(b) Serratia :
It is a motile coliform. It will grow in and on the hospital supplies. It causes urinary and respiratory tract infections. Hence, this option is incorrect.
(c) Enterobacter :
It is a lactose fermenting coliform. It is generally present in the digestive and respiratory tracts of humans and animals. It contaminates the dairy products. Hence, this option is correct.
(d) Proteus :
It is noncoliform opportunistic bacteria. It cannot ferment latose. It belongs to the family Enterobacteriaceae. Hence, this option is incorrect.
Hence, the correct option is (c) Enterobacter. The coliform bacterium that infects the dairy products is Enterobacter.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 5SA
An alcoholic is susceptible to pulmonary disease:
Explanation
Chronic alcohol consumption weakens multiple acute cellular functions in the lung. Moreover, leads to increase vulnerability to serious complications from pulmonary disease. In contrast, metabolism of alcohol increases oxidation levels. Oxidation damage to the cells impairs the capacity of the lungs to eliminate fluid. Oxidation damage also leads to reduction in immune response.
Thus, alcoholics have poor ability to clear aspirated oral secretions from their lower respiratory tracts; hence, they are more susceptible to pulmonary diseases.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 6CT
The hunter is likely to be infected by Francisella tularensis. This bacterium is very small, strictly aerobic, and Gram-negative coccobacillus that causes a zoonotic disease called tularemia. Hunters and hikers are mostly likely to contract this infection. The symptoms caused by due to tularemia include- fever, chills, headache, sore throat, muscle aches, and nausea. These symptoms are not distinct as these symptoms are very commonly occurring in any bacterial infection.
Following are few methods in which a laboratory scientist distinguishes among species:
- Francisella tularensis is a fastidious, facultative intracellular bacterium that needs cysteine for growth.
- F. tularensis grows poorly at 28°C, slowly at 35-37°C. This is a useful feature in differentiating from Yersinia pestis.
- Microscopic examination: Gram-negative bacteria, very small, pleomorphic, and poorly-staining.
Culture characteristics:
0 Exhibits poor growth on sheep blood agar.
0 Characteristic metallic sheen on cysteine heart agar that contains chocolatized blood. - The sub species can be identified by noting the history of the patient. The four sub species exist in different regions and therefore can be differentiated based on the location.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 6M
Yersinia pestis causes bubonic plague and pneumonic plague. It is an extremely virulent and non-pathogenic bacterium and has major historic impact.
This bacterium contains several virulence factors like adhesins (antigenic proteins) and Type III secretory system.
The adhesins make the way of entry of bacterium into the host cells. The Type III secretory system used to inject the antigenic proteins into the phagocytic cells, these antigenic proteins triggers the apoptosis process in phagocytic cells. Hence, the correct option is (a) Bubonic plague.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 6MC
Capsules of pathogenic enteric bacteria are virulence factors because they protect the bacteria from phagocytosis and from antibodies.
(a) Capture iron from haemoglobin and store it in the bacteria:
Siderophores capture iron from haemoglobin. They make the iron available to the bacteria. Hence, this option is incorrect.
(b) Release haemolysins that destroy red blood cells:
Haemolysins release nutrients by lysing the red blood cells. Capsules don’t release haemolysins. Hence, this option is incorrect.
(c) Produce fimbriae that enable the bacteria to attach to human cells:
Fimbriae and adhesins help the bacteria to attach more tightly to the human cells. Fimbriae are not produced by capsules. Hence, this option is incorrect.
(d) Protect the bacteria from phagocytosis and from antibodies:
Capsules provide a poorly immunogenic surface. They protect the bacteria from phagocytosis and antibodies. Hence, this option is correct.
Hence, the correct option is (d) protect the bacteria from phagocytosis and from antibodies. Capsules of pathogenic enteric bacteria are virulent because they protect the bacteria from phagocytosis and from antibodies.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 6SA
Following are the six factors that facilitate the production of disease by Bordetella pertussis :
Explanation
- Bordetella pertussis causes infection by inhibiting the action of ciliated epithelial cells of trachea. Various toxins and adhesins facilitate the disease.
- The bacterium adhered to certain lipids in the cytoplasmic membranes of tracheal cells via two adhesins: filamentous hemagglutinin and pertussis toxin.
- Filamentous hemagglutinin also attaches to certain glycoproteins on the cytoplasmic membranes of neutrophils; thus, commencing phagocytosis of bacteria.
- Bordetella pertussis persists inside the phagocytosis, while dodging the immune system.
- The toxin produced by pertussis, produce more receptors for filamentous hemmagglutin that leads to bacterial adhesion and phagocytosis.
- Bordetella pertussis produces four toxins:
a. Pertussis toxin, serves as both adhesion and a toxin. A portion of pertussis toxin obstructs metabolism of ciliated epithelial cells, resulting in increased mucus production.
b. Adenylate cyclase toxin elicits increased mucus production and impedes leukocyte movement, endocytosis, and killing. The function provides protection, for bacterium at early stage of infection.
c. Dermonecrotic toxin causes localized constriction and hemorrhage of blood vessels, which results in cell death and destruction of tissues.
d. Tracheal cytotoxin at low concentrations prevents the movement of cilia on ciliated respiratory cells. At high concentrations, causes the discharge of the cells from lining of trachea.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 7CT
The rash would have been caused by infection caused bacteria Pseudomonas aeruginosa. Pseudomonas aeruginosa is present almost everywhere and can thrive in disinfectant solution as well. The bacterium has a number of virulence factors. It is an opportunistic pathogen and cannot cause disease in healthy individuals because it normally cannot penetrate the skin and mucous membrane and also it cannot evade the host’s other defense mechanisms.
It is difficult to treat Pseudomonas aeruginosa as this bacterium is resistant to a wide range of antibacterial agents, including antimicrobial drugs, disinfectant soaps, antibacterial dyes, and quaternary ammonium sanitizers. The resistance acquired by the bacterium is due to the presence of non-specific drug antiports that pump some types of drugs out of the bacterium. Pseudomonas also forms biofilm which resists the penetration of the antibacterial drugs and disinfectants.
Physicians thus resort to various combinations of beta-lactam, aminoglycoside, and fluoroquinole antimicrobials. In cases where this treatment is not affective, a drug called Polymyxin which is also toxin to humans is administered.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 7MC
Petechiae are small red or purple coloured spots formed on the body due to minor haemorrhage (breaking of blood vessels). The bacterium which is responsible for the formation of petechiae in a host is Neisseria meningitidis.
(a) Neisseria meningitidis :
It causes meningococcal disease, which is life-threatening when it invades blood or cerebrospinal fluid. When it invades blood meningococcal septicemia is caused. The lipopolysaccharides trigger shock, which results in blood coagulation in many organs. It also causes petechiae on the trunk and lower extremities. Hence, this option is correct.
(b) Escherichia coli 0157:H7 :
It causes urinary tract infections and blood infections in the host. It does not cause petechiae. Hence, this option is incorrect.
(c) Klebsiella :
It causes pneumonia, bacteremia, meningitis, wound infections and urinary tract infections. It does not cause petechiae. Hence, this option is incorrect.
(d) Proteus mirabilis :
It causes urinary tract infections in the host. It does cause petechiae. Hence, this option is incorrect.
Hence, the correct option is (a) Neisseria meningitidis. The bacterium that is responsible for the formation of petechiae in a host is Neisseria meningitidis.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 7SA
Pseudomonas present on moist environment cause less disease, due to less prevalent gram negative bacteria:
Explanation
Pseudomonads are Gram-negative, aerobic rod belonging to the bacterial family Gammaproteobacteria. Pseudomonads are not particular in their growth requirements and are ubiquitous. Moreover, they are found everywhere – in soli, decaying organic matter, in moist environment, and hot tubs. Although, it is present everywhere it causes less disease than other less prevalent Gram-negative as Pseudomonads are opportunistic pathogen, which means that it exploits some break in the host defenses and can initiate an infection in only immune-compromised individuals.
Additionally, pseudomonads are epitome among opportunistic pathogens of humans. The bacterium in majority of cases does not infect immune-competent or uncompromised tissues. However, it is capable of infecting any tissue whose defenses are compromised due to some reason. It causes urinary tract infections, bone and joint infections, dermatitis, respiratory system infections, soft tissue infections, gastrointestinal infections, systemic infections, bacteremia in patients with severe burns, in cancer patients, and AIDS (acquired immunodeficiency syndrome). All the above mentioned infections weaken and suppress the immune system; thereby, making it favorable for Pseudomonads to attack.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 8CT
Based on symptoms the bacterium which could have caused diarrhea in this case is Shigella dysenteriae. Shigella causes a severe form of dysentery known as shigellosis, which is characterized by cramps, fever, diarrhea, and bloody stools. The 21 month old child is infected by Shigella dysenteriae.
The treatment of shigellosis includes replacement of fluids and electrolytes. As a precaution, oral antimicrobial drugs such as ciproflaxin, cephalosporin, should be administered to close contacts of the patient to check the spread of Shigella.
The family can take precaution and improve their personal hygiene. They might consider not involving children in cleaning of the cages where the contamination levels are high.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 8MC
Haemophilus influenza b is the most common cause of meningitis in children.
(a) Meningitis in children:
It is caused by Haemophilus influenzae b. The children within the age of 3-18 months get infected to this disease. This is controlled by immunization. Hence, this option is correct.
(b) Upper respiratory flu:
Haemophilus influenzae does not cause flu commonly. It is seen in the upper respiratory tract only. The strain Haemophilus influenzae a causes this flu. Hence, this option is incorrect.
(c) Endocarditis:
It is the infection to the heart valves. It is caused by Coxiella burnetti, Haemophilus parainfluenzae or Haemophilus aphrophilus. It is not caused by Haemophilus influenzae. Hence, this option is incorrect.
(d) Genital chancroid:
It is sexually transmitted. It is a genital ulcer. It is caused by Haemophilus ducreyi. Hence, this option is incorrect.
Hence, the correct option is (a) meningitis in children. The pathogen Haemophilus influenza b causes meningitis in children within the age of 3-18 months.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 8SA
Number of reported cases of pertussis in United States has increased, since 1970:
Explanation
Bordetella pertussis is gram-negative, non-motile, and aerobic coccobacillus. It causes pertussis, which is commonly known as whooping cough. Bordetella pertussis has no environmental and animal reservoir. They are effective vaccines available, as prophylactic measure, which can prevent from the infection. However, the number of pertussis cases reported has increased in United States, since the 1970s. This is because of the refusal of the parents to immunize their children. Even though vaccinations are administered, the immunity whether acquired or natural against this pathogens lasts only for 10 years.
Hence, to eradicate pertussis Centre for Disease Control recommends immunization of children and also one dose of adults under the age of 65 with a dose of cellular pertussis vaccine.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 9MC
Typically mild of the following diseases is cat scratch disease.
(a) Brazilian purpuric fever :
It is caused by the bacterium Haemophilus influenzae. It results in sepsis in children. It is fatal in some cases. Thus, it is not mild. Hence, this option is incorrect.
(b) Bartonellosis :
It is caused by Bartonella bacilliformis. It is characterized by severe anemia, fever, muscle and joint pains, headache and chronic skin infections. It is a fatal disease. Hence, this option is incorrect.
(c) Pediatric meningitis :
Haemophilus influenza b causes meningitis in children within the age of 3-18 months. It is characterized by inflammation of subcutaneous tissue, infantile arthritis, and fatal epiglottis. It is not a mild disease. Hence, this option is incorrect.
(d) Cat scratch disease :
Cat scratch disease is commonly called as cat scratch fever. It is generally benign and transmittable disease. It is caused by the intracellular bacterium Bartonella henselae. It is not fatal. Thus the cat scratch disease is typically mild as compared to the other given diseases. Hence, this option is correct.
Hence, the correct option is (d) cat scratch disease. The typically mild disease of all the given diseases is cat scratch disease.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 9SA
Illness caused by Legionella pneumophila:
Explanation
Legionella is a bacterium, which is transmitted through aerosols that are produced by air conditioning systems. Moreover, the bacterium causes two types of diseases namely:
Legionnaires’ disease (legionellosis) and Pontiac fever.
- Legionnaires’ disease (legionellosis):
Characterized by chills, dry non-productive cough, fever, headache, and pneumonia. The disease can be fatal in immunocompromised individuals, especially in heart and kidney transplants persons. - Pontiac fever:
The disease has all symptoms that are similar to legionellosis, except for pneumonia and is not fatal.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 10MC
The bacterium that causes infections in many burn victims is Pseudomonas aeruginosa.
(a) Moraxella catarrhalis :
It causes infections to the ear, eye, respiratory system, nervous system and joints in humans. It usually attacks the patients who have compromised immune system. Hence, this option is incorrect.
(b) Pseudomonas aeruginosa :
It can colonize any organ or system of the human body and cause infection to it. Pseudomonas infections are common in burn victims and cystic fibrosis patients. It develops nosocomial infections in almost two-third of the burn victims. Hence, this option is correct.
(c) Escherichia coli :
It causes urinary tract infections and blood infections in humans. It may be fatal in children and immune compromised adults. Hence, this option is incorrect.
(d) Bartonella bacilliformis :
It causes bartonellosis. It is often fatal. It is transmitted by very small sandflies. Hence, this option is incorrect.
Hence, the correct option is (b) Pseudomonas aeruginosa. The bacterium that causes infections in many burn victims is Pseudomonas aeruginosa.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 10SA
Coxiella burnetti is an aerobic, extremely small, obligate intracellular parasite that inhabits and reproduces in the acidic environment within phagolysosomes. Coxiella forms an internal, firm, resistant infective body, which is referred to as spore. The structure and function of this infective body or the spore is similar to the endospores of Gram-positive species. The infective body or the spore enables the bacterium to withstand extreme environmental conditions, such as desiccation and heat for years.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 11MC
Q fever is caused by Coxiella burnetti.
(a) For many years its cause was questio nable:
The cause of Q fever is unknown for many years. The pathogen causing this fever was not identified even after many years of its identification. The Q fever was named so as its cause was questionable for many years. Hence, this option is true of Q fever.
(b) It was first described in 1976 during an outbreak in Quincy, Massachusetts:
The pathogen Coxiella burnetti that causes Q fever was discovered in 1937. Before this discovery itself, the Q fever had been described. Hence, this option is false of Q fever.
(c) Researchers found it could be effectively treated with quinine:
Treatment of Q fever is very effective with antibiotics. The commonly used antibiotics to treat Q fever are doxycycline, tetracycline and chloramphenicol. Of these, oral doxycycline is preferred. Hence, this option is false of Q fever.
(d) The sharp spikes of fever on patients’ temperature charts resemble porcupine quills:
Sharp spikes of fever will not be formed on the patients’ temperature charts. Hence, this option is false of Q fever.
Hence, the correct option is (a) for many years its cause was questionable. This statement is true of Q fever as its cause is unknown for many years.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 11SA
The virulence factors that may cause disease in the Gram-negative anaerobes include outer wall membrane containing lipopolysaccharides, capsules, fimbriae, and proteases that degrade antibodies.
- Outer wall membrane:
It consists of lipopolysaccharides. The lipid A produced by Gram negative anaerobes has little endotoxin activity as compared to other Gram-negative bacteria. - Polysaccharide capsule and fimbriae:
Capsule is involved in adhesion to the host cell, abscess development, and inhibits phagocytosis. - Metabolic by-products (for example, short-chain fatty acids):
In case the bacterium is phagocytized, short-chain fatty acids produced during anaerobic metabolism restrict the activity of lysosomes, facilitating the bacteria to persist phagocytosis. This mechanism is considered as potentially relevant pathogenic mechanisms in anaerobic infections.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 12MC
The bile tolerant anaerobe is Bacteroides fragilis.
(a) Bacteriodes :
It is anaerobic bacteria. It is catalase positive and tolerant to bile. It can be cultured on bile-esculin agar, which differentiates aerobic and most anaerobic bacteria. Hence, this option is correct.
(b) Escherichia :
It is Gram-negative facultative anaerobe. It is a rod shaped bacteria. It causes urinary tract infections. It is sensitive to bile. Hence, this option is incorrect.
(c) Shigella :
It is Gram-negative facultative anaerobe. It is non-motile bacilli. It causes shigellosis in humans. It is sensitive to bile. Hence, this option is incorrect.
(d) Prevotella :
It is Gram-negative. It is an anaerobe. It causes respiratory tract infections. It is sensitive to bile. Hence, this option is incorrect.
Hence, the correct option is (a) Bacteriodes. The bile tolerant anaerobe in all the given anaerobes is Bacteriodes.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 12SA
Oxidase test is the single biochemical test result that distinguishes gammaproteobacteria in the family Enterobacteriaceae from gammaproteobacteria in the family Pasteurellaceae.
The oxidase test is a test used to determine if a bacterium yields certain cytochrome c oxidases.
- Gammaproteobacteria of the family Enterobacteriaceae are oxidase negative.
- Gammaproteobacteria of the family Pasteurellaceae are oxidase positive.
Microbiology with Diseases by Taxonomy Chapter 20 Answers 13SA
Rickettsia rickettsii is the causative agent of Rocky Mountain spotted fever, which is the most severe and prevalent among rickettsial illness. Rickettsia rickettsii is transmitted among humans and rodents (act as reservoir) by hard ticks in the genus Dermacentor through a process called transovarian transmission.
Transovarian transmission is a process in which male ticks infect female ticks during mating. The female tick spreads the bacteria to eggs forming in their ovaries. Rickettsia rickettsii is inactive or dormant in the salivary glands of the tick and gets activated only after the arachnids feed actively for several hours. The active bacteria are released from the tick’s salivary glands into the mammalian host’s circulatory system where they infect endothelial cells lining small blood vessels.