MCQ Bacteriology 11
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.
MCQ Bacteriology 12
A 21 year newly married woman developed a urinary tract infection (UTI). 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,
b. K antigens
c. Metabolic properties
d. P fimbriae
MCQ Bacteriology 13
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
e. The release of interferon-gamma and other macrophage activating cytokines
MCQ Bacteriology 14
A mutation in DNA gyrase is likely to result in resistance to which one of the following antibiotics?
a. Amphotericin B
MCQ Bacteriology 15
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
MCQ Bacteriology 16
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.
MCQ Bacteriology 17
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
MCQ Bacteriology 18
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?
b. Nicotinamide adenine dinucleotide (NAD)
e. Protein A
MCQ Bacteriology 19
Which one of the following bacteria is most 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
MCQ Bacteriology 20
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
11. b. Bacterial inhibition of phagolysosome formation and interference with endosomal acidification
12.d. P fimbriae
15.a. Alternation of the major target for the drug (i.e. Penicillin Binding Proteins)
16.d. increased generation of cyclic adenosine monophosphate (cAMP)
17.b. gene carried by a lysogenic phage
18.b. Nicotinamide adenine dinucleotide (NAD) i.e. Factor V
19. c. Staphylococcus aureus
20. e. Vibrio parahemolyticus (It is commonly found in brackish/saltwater of sea).