Nokea
The bacterium that shows swarming on blood agar
- A. providencia stuartii
- B. providencia rettgeri
- C. Proteus mirabilis
- D. morganella morganii
Correct Answer: C
Rationale: The correct answer is C: Proteus mirabilis. This bacterium shows swarming on blood agar due to its ability to produce flagella and exhibit rapid and coordinated movement. Providencia stuartii and Providencia rettgeri are not known for swarming behavior on blood agar. Morganella morganii can exhibit swarming motility, but it is not as commonly associated with this characteristic compared to Proteus mirabilis, making C the most appropriate choice.
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Which of the following viruses can cause hemorrhagic cystitis?
- A. BK virus
- B. Enteroviruses
- C. Flaviviruses
- D. Coronaviruses
Correct Answer: A
Rationale: The correct answer is A: BK virus. BK virus is a common cause of hemorrhagic cystitis, especially in immunocompromised individuals. It infects the urinary tract, leading to inflammation and bleeding in the bladder. Enteroviruses, Flaviviruses, and Coronaviruses do not typically cause hemorrhagic cystitis. Enteroviruses usually cause respiratory and gastrointestinal infections, Flaviviruses are commonly associated with diseases like dengue fever and Zika virus, and Coronaviruses are known for causing respiratory illnesses such as COVID-19. Hence, the correct answer is A as it is the only virus among the options known to cause hemorrhagic cystitis.
The most common cause of cystitis (after Escherichia coli) in healthy sexually active women is:
- A. Staphylococcus saprophyticus
- B. Proteus mirabilis
- C. Pseudomonas aeruginosa
- D. Klebsiella pneumoniae
Correct Answer: A
Rationale: The correct answer is A: Staphylococcus saprophyticus. This bacterium is the second most common cause of cystitis in healthy sexually active women after E. coli. Staphylococcus saprophyticus is commonly found in the gastrointestinal and genital areas. It has a unique ability to adhere to uroepithelial cells, making it a common pathogen in urinary tract infections. Proteus mirabilis is more commonly associated with complicated UTIs, especially in catheterized patients. Pseudomonas aeruginosa is more commonly seen in hospitalized or immunocompromised patients. Klebsiella pneumoniae is typically associated with UTIs in elderly patients or those with structural abnormalities in the urinary tract.
Which of the following bacteria are capable of surviving in low-oxygen environments?
- A. Obligate anaerobes
- B. Facultative anaerobes
- C. Obligate aerobes
- D. Microaerophiles
Correct Answer: B
Rationale: The correct answer is B: Facultative anaerobes. Facultative anaerobes can survive in both oxygen-rich and oxygen-poor environments by switching between aerobic and anaerobic metabolism. They have the flexibility to use oxygen if present but can also ferment in the absence of oxygen. Obligate anaerobes (A) cannot survive in the presence of oxygen, obligate aerobes (C) require oxygen for survival, and microaerophiles (D) require low levels of oxygen for growth, unlike facultative anaerobes.
A wound swab from a patient with a deep tissue infection revealed Gram-positive rods with terminal spores. What is the most likely causative agent?
- A. Clostridium perfringens
- B. Bacillus anthracis
- C. Clostridium tetani
- D. Bacillus cereus
Correct Answer: A
Rationale: The correct answer is A: Clostridium perfringens. This is because Clostridium perfringens is a Gram-positive rod bacterium that forms terminal spores. It is commonly associated with deep tissue infections and can cause gas gangrene. Bacillus anthracis (B) causes anthrax and does not typically form spores at the terminal end. Clostridium tetani (C) causes tetanus and Bacillus cereus (D) is more commonly associated with food poisoning. In this case, the presence of terminal spores along with the clinical presentation of a deep tissue infection points towards Clostridium perfringens as the most likely causative agent.
Microscopy of a sputum smear revealed acid-fast bacilli stained red using the Ziehl-Neelsen method. What is the most likely diagnosis?
- A. Tuberculosis
- B. Leprosy
- C. Diphtheria
- D. Pneumonia
Correct Answer: A
Rationale: The presence of acid-fast bacilli stained red using the Ziehl-Neelsen method indicates a mycobacterial infection. Among the choices, tuberculosis is the most common mycobacterial infection affecting the lungs, presenting with acid-fast bacilli in sputum. Leprosy is caused by Mycobacterium leprae, but it typically does not show up in sputum smears. Diphtheria is caused by Corynebacterium diphtheriae, which is not acid-fast. Pneumonia is a general term for lung inflammation caused by various pathogens, not specifically mycobacteria. Therefore, the correct diagnosis is tuberculosis based on the microscopy findings.