Free Bacteriology MCQs with Answers
167 Bacteriology MCQs from Microbiology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
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167 questions · page 6 of 9
- A. It is composed of DNA
- B. It doe not contain histones
- C. It is circular
- D. Its DNA has both introns and extrons
Explanation: Typical bacterial genomes are DNA, usually circular, and generally lack the intron-exon organisation common in eukaryotic genes.
Correct answer: Its DNA has both introns and extrons- A. Cocci
- B. Spirochetes
- C. Bacteriophages
- D. Filamentous rods
Explanation: Spirochetes, especially Treponema species, can penetrate non-necrotic tissue in advance of other organisms during necrotising ulcerative…
Correct answer: Spirochetes- A. Capsule
- B. Fimbria
- C. Flagella
- D. None of the above
Explanation: Fimbriae are short, hair-like surface structures that mediate attachment of bacteria to host cells.
Correct answer: Fimbria- A. Haemorrhage
- B. perforation
- C. Osteomyelitis
- D. All of the above
Explanation: Typhoid fever may cause intestinal haemorrhage and perforation, and Salmonella Typhi can produce extraintestinal complications such as…
Correct answer: All of the above- A. Feacus
- B. Urine
- C. Blood
- D. All of the above
Explanation: During the initial phase of typhoid fever, Salmonella Typhi is multiplying in the bloodstream, so blood culture is the best diagnostic…
Correct answer: Blood- A. Bunch of a
- B. Chain of beads
- C. Drum stick
- D. Safely pin
Explanation: Clostridium tetani forms a terminal spherical spore that gives the bacillus a characteristic drum-stick appearance.
Correct answer: Drum stick- A. Scanning microscope
- B. Inverted microscope
- C. Dark ground microscope
- D. Electron microscope
Explanation: Leptospira are very thin, motile spirochaetes and are difficult to see by ordinary light microscopy, so urine can be examined by…
Correct answer: Dark ground microscope- A. Viral stomatitis
- B. Diptheria
- C. Tuberculosis
- D. Typhoid fever
Explanation: Typhoid fever is a classic food- and water-borne infection caused by ingestion of Salmonella Typhi.
Correct answer: Typhoid fever- A. Tannerella
- B. Porphyromonas
- C. Buccae
- D. Prevotella
Explanation: Black-pigmented anaerobic oral bacteria include Porphyromonas, Prevotella and Tannerella.
Correct answer: Buccae- A. Most common cause is B. Petrussis
- B. It may occur in children and young adult after vaccination
- C. Bacteria culture from nasopharyngeal swab is the definitive diagnosis
- D. Presence of antibodies in serum in diagnostic of the disease
Explanation: Bordetella pertussis is usually identified by culture from a properly collected nasopharyngeal specimen, and serological testing can…
Correct answer: Presence of antibodies in serum in diagnostic of the disease- A. Actinomyces viscosus
- B. Lactobacillus acidophilus
- C. Streptococcus mutans
- D. Veilonella parvula
Explanation: The salivary peroxidase-thiocyanate-hydrogen peroxide system inhibits several oral bacteria, with Lactobacillus acidophilus being the…
Correct answer: Lactobacillus acidophilus- A. Strick aerobes
- B. Can grow in disinfectants in hospital
- C. Infection is mostly due to endogenous source
- D. Most common organism is burn patient
Explanation: Pseudomonas aeruginosa is an aerobic, environmentally hardy organism that can survive in disinfectant solutions and is a major pathogen in…
Correct answer: Infection is mostly due to endogenous source- A. Diagnosis
- B. Prognosis
- C. Treatment plan
- D. Epidemiology
Explanation: The lepromin test reflects the host's cell-mediated immune response and helps assess the prognosis or type of leprosy, not establish the…
Correct answer: Prognosis- A. Base lines differ depending on the endemicity of the disease
- B. O antibodiest last longer and hence is not indicative of recent infection
- C. H antigen cannot differentiate between subtypes
- D. High titre value in a single widal test is not confirmative
Explanation: The statement about O antibodies is false because O agglutinins appear early and decline relatively soon, making them more useful for…
Correct answer: O antibodiest last longer and hence is not indicative of recent infection- A. Faeces & urine of rodents is the cause
- B. Onset of IgM in 2 days
- C. Incubation period is 10 days
- D. It is sensitive to penicillin
Explanation: Leptospira-specific IgM usually becomes detectable after about 5 to 7 days, not within 2 days of illness.
Correct answer: Onset of IgM in 2 days- A. Invasion
- B. Endotoxin
- C. Exotoxin
- D. Capsule
Explanation: Corynebacterium diphtheriae causes disease mainly through diphtheria exotoxin, which inhibits host protein synthesis by inactivating…
Correct answer: Exotoxin- A. Ulcerative gingivostomatitis
- B. Caused due to malnutrition
- C. A symbiotic infection
- D. Caused by leptospira interrogans
Explanation: Vincent's angina is a necrotising ulcerative gingivostomatitis caused by a synergistic fusospirochetal infection, especially Fusobacterium…
Correct answer: Caused by leptospira interrogans- A. Rheumatoid arthritis
- B. Typhoid fever
- C. Rheumatie fever
- D. Rickettsial fever
Explanation: ASO detects antibodies against streptolysin O and supports recent group A streptococcal infection.
Correct answer: Rheumatie fever- A. Clostridium botulinum
- B. Clostridium welchii
- C. Clostridium tetani
- D. Clostridium difficile
Explanation: Clostridium perfringens, formerly called Clostridium welchii, is the commonest clostridial cause of gas gangrene. C. tetani and C.
Correct answer: Clostridium welchii- A. ADP - ribosylation of the G regulatory protein
- B. Inhibition of adenyl cyclase
- C. Activation of GTPase
- D. Active absorption of NaCI
Explanation: Cholera toxin ADP-ribosylates the stimulatory G protein, Gs, locking it in an active state and causing persistent adenylate cyclase…
Correct answer: ADP - ribosylation of the G regulatory protein