MCQ Microbiology: Infectious Disease, Bacteriology

1. The survival of Mycobacteria after ingestion by macrophages is attributed to
   a. Bacterial inhibition of complement activation via the alternative pathway.
   b. Bacterial inhibition of phagolysosome formation and interference with endosomal acidification
   c. The poor immunogenicity of the cell wall glycolipids.
   d. The bacterium's rapid escape from the endosome into the cytoplasm of infected cells.
   e. The bacterium's resistance to oxygen-active radicals released into the phagolysomsome.
2. A 21 year newly married woman developed a urinary tract infection. At the time she sought medical advice, she was febrile and complained of painful urination and flank pain. Her urine appeared “cloudy”. Urine culture yields a lactose-fermenting, indole-positive, Gram-negative bacillus. The infectiveness of the organism responsible for this urinary tract infection is associated with specific,
   a. exotoxins
   b. K antigens
   c. Metabolic properties
   d. P fimbriae
   e. Plasmids
   
   
   
3. The role of bacterial capsules as virulence factors is usually related to their ability to interfere with
   a. Antibody binding
   b. B lymphocyte activation
   c. Antibacterial penetration of bacterial cells
   d. Phagocytosis
   e. The release of interferon gamma and other macrophage activating cytokines
4. A mutation in DNA gyrase is likely to result in resistance to which one of the following antibiotics?
   a. Amphotericin B
   b. Ciprofloxacin
   c. Penicillin
   d. Rifampin
   e. Streptomycin
5. Resistance of Staphylococcus aureus to methicillin is most often caused by
   a. Alternation of the major target for the drug
   b. cell membrane impermeability
   c. decreased uptake of the antibiotic
   d. Inactivation of autolysins
   e. Synthesis of a potent Beta Lactamase
6. The molecular basis for the effect of cholera toxin on duodenal mucosal cells is
   a. Activation of adenylate Cyclase
   b. Inactivation of a G1 protein
   c. Increased activity of potassium pumps
   d. increased generation of cyclic adenosine monophosphate (cAMP)
   e. Ribosylation of a guanosine triphosphate (GTP) binding protein.
7. The synthesis of erythrogenic toxin by specific strains of group A Streptococcus is determined by a
   a. Bacterial chromosomal gene
   b. gene carried by a lysogenic phage
   c. Specific virulence plasmid
   d. Transposon
8. Which one of the following factors released by heating a suspension of sheep erythrocytes is required for the growth of Haemophilus Influenzae in chocolate agar?
   a. Coagulase
   b. Nicotinamide adenine dinucleotide (NAD)
   c. Hemoglobin
   d. Hemolysin
   e. Protein A
9. Which one of the following bacteria is mostl likely to be relatively resistant to antibiotics as a result of the relative impermeability of its cell wall?
   a. Haemophilus influenzae
   b. Pseudomonas aeruginosa
   c. Staphylococcus aureus
   d. Streptococcus pneumoniae
   e. Streptococcus pyogenes
10. A patient develops explosive, watery diarrhea 24 hours after eating seafood. What bacterium is most likely involved?
    a. Campylobacter fetus
    b. Salmonella typhimurium
    c. Shigella flexneri
    d. Vibrio cholerae
    e. Vibrio parahaemolyticus
    
    

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