Free Bacteriology MCQs with Answers

• A. Cardiolipin
• B. Plasminogen
• C. Palmityl lecithin
• D. Serine

Explanation: The reagin test for syphilis is a non-treponemal test that detects antibodies against cardiolipin-lecithin-cholesterol complexes.

• A. Incubation period of 24 hours
• B. Requires immediate antibiotics
• C. Common with dairy products
• D. Heat labile enterotoxin

Explanation: Staphylococcal food poisoning is commonly linked to contaminated dairy products and has a short incubation of about 1–6 hours.

• A. Culture
• B. Gram stain
• C. Biochemical reaction
• D. Haemagglutination test

Explanation: Fimbriae, also called adhesins or pili, can be demonstrated by their ability to produce haemagglutination of red blood cells.

• A. Group A
• B. Group B
• C. Group C
• D. Group D

Explanation: The CAMP reaction is characteristically positive with Group B Streptococcus, Streptococcus agalactiae, which enhances the haemolysis…

• A. Y. pestis
• B. Pertussis
• C. Mycoplasma
• D. M-Tuberculosis

Explanation: The cough plate method is used to isolate Bordetella pertussis from droplets expelled by a coughing patient.

• A. Aryl sulphatase test
• B. Niacin test
• C. Neutral red test
• D. Catalase peroxidase test

Explanation: The neutral red test helps distinguish virulent from avirulent tubercle bacilli because virulent strains produce a characteristic uptake…

• A. Spirochaetes
• B. Fusiform bacilli
• C. Treponema vincenti
• D. None of the above

Explanation: Borrelia vincentii is classically found with fusiform bacilli in Vincent’s angina, an oral mixed infection.

• A. Neisseria meningitides
• B. Salmonella typhi
• C. Streptococcus pyogenes
• D. Legionella pneumophila

Explanation: Salmonella typhi, Legionella pneumophila and Neisseria meningitidis can persist within host cells, whereas Streptococcus pyogenes is…

• A. Trachoma
• B. Non-gonococcal urethritis
• C. Pneumonia
• D. Parotitis

Explanation: Chlamydia trachomatis causes trachoma, nongonococcal urethritis and an atypical form of pneumonia.

• A. M Protein
• B. Polysaccharide C antigen
• C. Type of lipid in cell membrane
• D. Physiological properties

Explanation: Lancefield grouping depends on the group-specific carbohydrate, called the C antigen, in the streptococcal cell wall.

• A. Niacin test
• B. AFB staining
• C. Pas staining
• D. None of the above

Explanation: Mycobacterium tuberculosis is characteristically niacin-positive, whereas most atypical mycobacteria are niacin-negative.

• A. Coagulase
• B. Hyaluronidase
• C. Lecithinase
• D. None of the above

Explanation: The Nagler reaction detects lecithinase activity, particularly the alpha toxin of Clostridium perfringens, by producing an opaque…

• A. Rickettsia tsutsugamushi
• B. R. prowozekii
• C. R. quintana
• D. C. burnetti

Explanation: Q fever is caused by Coxiella burnetii, an obligate intracellular organism formerly classified with the rickettsiae.

• A. Gram positive bacteria
• B. Gram negative bacteria
• C. Fungus
• D. A yeast like form

Explanation: Actinomycetes are filamentous, branching, Gram-positive bacteria that can resemble fungi because of their thread-like growth.

• A. Non - Specific
• B. Slide flocculation test
• C. Best followed for drug therapy
• D. All of the above

Explanation: VDRL is a non-specific flocculation test that detects reagin antibodies rather than antibodies directed specifically against Treponema…

• A. Osteomyelitis
• B. Abscess
• C. Scarlet fever
• D. Pneumonia

Explanation: Staphylococci commonly cause osteomyelitis, abscesses and pneumonia. Scarlet fever is caused by erythrogenic toxin-producing Streptococcus…

• A. Koch
• B. Medintoff
• C. John snow
• D. Virchow

Explanation: Robert Koch identified Vibrio cholerae as the causative organism of cholera in 1883.

• A. Pili
• B. Cell Membrane
• C. Its intracellular location
• D. Cytolytic enzymes

Explanation: Gonococcal pili help Neisseria gonorrhoeae attach to mucosal epithelial cells and resist clearance, making them an important virulence…

• A. Bacillus anthracis
• B. Brucella species
• C. Bordetelia pertussis
• D. Clostridium weichii

Explanation: Bordetella pertussis produces a characteristic thumbprint-like appearance in a culture film smear.

• A. Plague
• B. Leprosy
• C. Pemhigoid
• D. Typhoid

Explanation: The Widal test detects agglutinating antibodies against the O and H antigens of Salmonella Typhi and related salmonellae, so it is used in…