12 Year 2: Microbiology exam questions on Untitled for medical students. Includes MCQs, answers, explanations and written questions. Sample: A paroxysm is a and
This MCQ set contains 12 questions on Untitled in the Year 2: Microbiology unit. Each question includes the correct answer and a detailed explanation for active recall and exam preparation.
Correct answer: E – Rapid-fire cough; pertussis
A paroxysm is a sudden, uncontrollable series of coughs characteristic of pertussis (whooping cough) caused by Bordetella pertussis. The paroxysmal stage features severe coughing fits followed by an inspiratory "whoop" sound, often accompanied by post-tussive vomiting. ---
Correct answer: D – Antitoxin
Botulism requires administration of botulinum antitoxin (trivalent or heptavalent). The antitoxin neutralizes circulating toxin but cannot reverse already bound toxin. Early administration is critical. Antibiotics are ineffective against the preformed toxin. ---
Correct answer: C – Anaerobic
Clostridium perfringens is an obligate anaerobe that multiplies only in oxygen-free environments. Improper food storage (inadequate cooling or reheating) creates anaerobic conditions that allow spore germination and toxin production, leading to food poisoning. ---
Correct answer: D – Inhalation; anthrax
Woolsorter's disease is pulmonary anthrax caused by inhaling Bacillus anthracis spores from contaminated animal products (wool, hides). It causes severe hemorrhagic mediastinitis, septic shock, and high mortality. The name comes from textile workers who processed contaminated wool. ---
Correct answer: B – Gonorrhea and chlamydia
Ophthalmia neonatorum (neonatal conjunctivitis) is caused by Neisseria gonorrhoeae and Chlamydia trachomatis acquired during passage through an infected birth canal. Both can cause severe conjunctivitis and, if untreated, corneal scarring and blindness. ---
Correct answer: D – Bacillus anthracis
Robert Koch first proved Bacillus anthracis as the causative agent of anthrax in 1876, establishing Koch's postulates. He isolated the organism from diseased animals, cultured it in pure form, reproduced the disease in healthy animals, and re-isolated the same organism. ---
Correct answer: D – Inhibits elongation factor 2
Diphtheria toxin is an A-B toxin. The A subunit catalyzes ADP-ribosylation of elongation factor 2 (EF-2), irreversibly inactivating it and blocking protein synthesis. One toxin molecule can kill a cell by halting translation. ---
Correct answer: D – Ribosome
Ribosomes are internal structures with highly conserved proteins across species, making them poor serological markers. Capsule (K antigens), cell wall (O antigens for LPS), and flagella (H antigens) are surface-exposed and variable, making them excellent for serotyping. ---
Correct answer: C – Pasteurella bettyae
Pasteurella bettyae (formerly CDC group HB-5) is associated with genital tract infections and neonatal infections. P. multocida is primarily associated with animal bites and respiratory infections, not genital tract infections. ---
Correct answer: D – Q Fever
Q fever (Coxiella burnetii) is best diagnosed serologically by detecting antibodies to phase I and II antigens. The organism is difficult to culture due to obligate intracellular nature. TB, gonorrhea, and actinomycosis are diagnosed by culture/microscopy. ---
Correct answer: C – Streptococcus pyrogens
S. pyogenes (Group A Strep) rarely causes meningitis. The three most common causes of bacterial meningitis are S. pneumoniae (most common overall), N. meningitidis (especially in young adults), and H. influenzae type b (reduced since Hib vaccine). ---
Correct answer: A – Airway colonization in a cystic fibrosis patient with a mucoid (alginate-producing) strain of Pseudomonas aeruginosa
Mucoid P. aeruginosa produces alginate exopolysaccharide that forms thick biofilms in CF patient airways. These biofilms protect bacteria from antibiotics and immune clearance, causing chronic infection. Biofilm formation is a hallmark of CF pulmonary infection. ---