541. Which of the following statement regarding microbial spread is FALSE?
A. Microbial spread tends to occur along tissue planes rather than across tissue planes.
B. Microbial access to bloodstream is usually via lymphatics.
C. All 2° foci of infection are small & multiple (ie. millet spread).
D. Persistant bacteraemia results in triggering of cytokines & mediators, leading to host septic responses.
E. Major sites of infection can be distal to the portal of entry.

542. Which of the following statements regarding vertical transmission of infection is FALSE?
A. Treponema pallidum crosses placenta at the end of 2nd trimester to cause congenital syphillus.
B. Toxoplasmosis infection is most dangerous late in pregnancy
C. Bacterial & mycoplasmal placentitis can cause premature delivery & stillbirth.
D. Vertical transmission of infection must be transplacental infection.
E. All of the above.

543. Which of the following statement regarding microbial transmission is FALSE?
A. Salivary gland viruses are primarily transmitted by aerosol.
B. Contagious agents are those that are directly transmissible from person to person via contact or aerosol.
C. Bacterial spores or protozoan cysts can survive in cool, dry environment.
D. Aerosol transmission of bacteria & fungi only occur if there is open lesions in the airway.
E. None of the above

544. Which of the following statements regarding viral infection is TRUE?
A. Viral tropism for host cells is partly due to presence of specific host cell receptors.
B. Some microbes induce host cell damage by evoking tissue damaging host immune responses.
C. Uncoating of viruses within host cells leads to lost of viral infectivity.
D. Each virus family uses specific enzymes for transcription & replication.
E. All of the above.

545. Virus may kill host cells by:
A. Lysis of host cell by inserting viral protein into host cell membrane.
B. Inhibition of host cell DNA, RNA or protein synthesis.
C. Evoke damaging host immune response by expression of viral protein on host cell surface.
D. Causing neoplastic growth
E. All of the above.

546. Which of the following statement is INCORRECT?
A. Gram positive bacterial membrane lipoteichoic acid only binds to blood cells & oral epithelial cells.
B. Sex pili of bacteria is used to transmit plasmids or transposons between bacteria.
C. Bacterial tropism for host cell type is determined by minor protein on the tip of the pili.
D. Each bacteria may have trophism for more than one cell type
E. All of the above

547. Which of the following pairing of intracellular facultative bacteria & their trophic cell type is FALSE?
A. Shigella – Epithelial cell.
B. Mycobacteria tuberculosis – Macrophage
C. Salmonella typhi – Epithelium & macrophage.
D. Legionella pneumophilia – Epithelial cell.
E. Yersinia – Macrophage

548. Which of the following statements regarding intracellular bacteria action in the cytoplasm is FALSE?
A. Enteroinvasive E coli inhibits host protein synthesis & rapidly replicate to lyse host cell.
B. Mycobacteria tuberculosis replicates in the macrophage phagolysosome
C. Legionella replicates within macrophage, and so avoided host immune response.
D. Toxoplasmosis inhibits increase of acidification that occurs with lysosome -endosome fusion.
E. Salmonella replicates in macrophage phagolysosome.

549. Which of the following is NOT an example of exotoxin?
A. Diptheria toxin
B. Lipopolysaccahride
C. Vibrio cholerae enterotoxin
D. Clostridium perfringens alpha toxin
E. None of the above.

550. Which of the following statements regarding immune evasion is INCORRECT?
A. Clostridium difficle propogates in the intestinal lumen, and so is inaccessible to host immune defenses including secretory 19A.
B. Malaria invade hepatocytes before host immune response becomes effective.
C. Hemophilus Influenzae type b hide their antigen within the carbohydrate capsule & so escape phagocytosis.
D. Pneumococci changes their surface antigen during the infection to prevent immune clearance.
E. Pseudomonas secrete leukotoxin to kill neutrophils.

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