ANTIMICROBIAL CHEMOTHERAPY 1

Question 1

antibiotics contraindicated in pregnancy

Answer 1

Albendazole
Erythromycin estolate
Doxycycline
Streptomy
Tetracycline

Question 2

Antibiotics contraindicated in lactation

Answer 2

Chloramphenicol
Metronidazole

Question 3

What are bacteriostatic antibiotics?

Answer 3

• Inhibit growth and multiplication of organisms
• tetracycline, chloramphenicol, sulphonamides , erythromycin

Question 4

What are bactericidal antibiotics

Answer 4

-irreversible damage and destroying of organism
- penicillin, aminoglycosides, rifampicin, high dose of erythromycin, metronidazole and the quinolones

Question 5

Purpose of drug interactions

Answer 5

1. To prevent development of resistance : TB TREATMENT
2. To broaden the spectrum of activity in mixed infections (GIT infections)
3. synergistic effects ( aminoglycosides and B lactam)
4. To potentiate activity of the drug ( amoxicillin+ clavulanic acid)
5. To enhance the therapeutic effect (penicillin and probenecid)

Question 6

Undesirable drug interactions

Answer 6

P19 & 18

Question 7

Enzyme inducers

Answer 7

Rifampicin

Question 8

Enzyme inhibitors

Answer 8

• erythromycin, chloramphenicol, sulphonamides, metronidazole, ciprofloxacin

Question 9

Antibiotic stewardship

Answer 9

• consider de-escalation once results are available
• consider switching from IV to orla once the patient is stable
• stop antibiotics ASAP

Question 10

2 AB classes commonly linked to collateral damage

Answer 10

Cephalosporin & Fluoroquinolones

Question 11

Duration on therapy depends on?

Answer 11

• site of infection
• severity of illness and response to treatment
• AB can be discontinued w/in 48-72 hours of the temperature returning to normal
• infections at certain siites

Question 12

How can resistance be avoided?

Answer 12

Avoid unnecessary and inappropriate use of ABs
- use lower than effective doses
- avoid inappropriate dosing intervals, use of broad spectrum agents, use of combination ABs
- avoid using bacteriostatic agents in immunodeficiency states
- stop continuing an antibiotic in the presence of resistance

Question 13

Susceptibility testing: minimum inhibitory concentration & breakpoint

Answer 13

MIC: the lowest concentration that inhibits bacterial growth. Correlates with clinical response
Breakpoint: (c) of an AB at which a particular bacterium is considered susceptible, intermediate or resistant to the drug

Question 14

Drugs : time dependent killing

Answer 14

B-Lactams, Macrolides, Clindamycin

Question 16

Concentration dependent killing drugs

Answer 16

Aminoglycosides, Quinolones

Question 17

Use of ABs for chemoprophylaxis: Meningococcal meningitis

Answer 17

1. Ciprofloxacin: 500mg single dose p.o or
2. Ceftriaxone - 250mg single dose imi or
   Rifampicin (600mg bd for 2 days)

Question 18

Use of ABs for chemoprophylaxis: prevention of recurrence of rheumatic fever

Answer 18

1. Benzathine penicillin (bicillin 1.2 mil U every 3-4 weeks)
2. Penicillin V (Pen VK 250mg b.d)

Prevention of peri-operative infections

Question 19

Use of ABs for chemoprophylaxis: chemoprophylaxis for HIV

Answer 19

• cotrimoxazole for PCP prophylaxis. 1 DS tab per day or 3x per week

Question 20

Use of ABs for chemoprophylaxis: prevention of infective endocarditis

Answer 20

1. Dental procedures : Amoxicillin , 2 g 1 hour before procedure or
   Clindamycin :600mg 1 hour before procedure
2. genitourinary or gastrointestinal procedures

• ampicillin
  +
  Gentamycin
  Then
  Amoxicillin

Malaria prophylaxis and TB

Question 21

Cardiac condition in which antimicrobial prophylaxis indicated

Answer 21

High risk:
- prosthetic heart valves
- complex congenital cyanotic heart diseases
- previous infective endocarditis
- surgical constructed systemic or pulmonary conduits

Question 22

Dental procedures that do not require endocarditis prophylaxis

Answer 22

-routine anesthetic injections through non infected tissues
- taking dental radiographs
- Placement of removable prosthodontic or orthodontic appliances
- adjustment of orthodontic appliances
- placement of orthodontic brackets
- shedding of deciduous teeth
- bleeding from trauma to the lips or oral mucosa