Test 40 (microbiology)

1. The following are true about tetanus acquired through traumatic wound:

a. the diagnosis is depends on microbial findings

b. Clostridium tetani travels via the nerves to the anterior horn 
    cells in the spinal cord

c. the tetanospasmin component of the exotoxin acts on the 
    post-synaptic neurones and prevents impulse transmission.

d. the patient should be given antitoxin intravenously

e. the presence of Clostridium tetani in the wound can be 
    identified by a positive Nagler reaction
 

Answera.F   b.F   c.F   d.T   e.F
The diagnosis is usually clinical.
The toxin and not the bacteria spreads beyond the wound.
The tetanospasmin acts on synapses to inhibit the normal inhibitory control of motor nerve impulses.
A positive Nagler reaction identifies the presence of Clostridium perfringes

2. Hepatitis B virus:

a. is a DNA virus

b. the presence of e antigen indicates increased infectivity

c. antibody to surface antigen usually appears within 2 weeks 
    of infection

d. the carrier rate is about 0.1% in the UK

e. is a recognized cause of liver cancer

Answera.T   b.T   c.F   d.T   e.T
Antibody to surface antigen usually appears late and indicates immunity.
 

3. The following drugs act by inhibiting cell wall synthesis of the 
    micro-organisms:

a. vancomycin

b. gentamicin

c. cefuroxime

d. amphotericin B

e. erythromycin.

Answera.T   b.F   c.T   d.F   e.F
Gentamicin and erytromycin inhibit protein synthesis by ribosomes
Amphotericin B disrupts the cell membrane and affects its barrier function
 

4. The Mantoux test:

a. is positive in all patients with tuberculosis

b. involves injecting PPD (purified protein derivative) 
    intradermally

c. is more sensitive than the tine test

d. becomes positive within 3 weeks of acquiring tuberculosis

e. involves the CD4 cells

Answera.F   b.T   c.T   d.F   e.T
In patients who recently acquire tuberculosis or in those with overwhelming tuberculosis the Mantoux test may be negative.
The Mantoux test does not become positive until 3 to 7 weeks after acquiring the infection
 

5. The following are true about Pseudomonas aeruginosa:

a. it is the most common cause of contact lens acquired 
    infection

b. it is a Gram negative bacteria

c. it can cause osteomyelitis

d. it is sensitive to chloramphenicol

e. it is sensitive to ciprofloxacin

Answera.T   b.T   c.T   d.F   e.T