Microbiology/ Abx

Question 1

What antibiotics are active against gram +ve and gram -ve abx?

Answer 1

Co-amoxiclav
Pipericillin/Tazobactam (Tazocin)
Ertapenem
Imipenem
Meropenem

Cefuroxime (no anaerobic cover)
Cefotaxime (no anaerobic cover)
Ceftriaxone (no anaerobic cover)

Question 2

What antibiotics have anaerobic cover?

Answer 2

Co-amoxiclav
Piperacillin/Tazobactam (Tazocin)
Ertapenem
Imipenem
Meropenem
Clindamycin
Metronidazole

Question 3

A patient has a perforated appendix. Which antibiotics could be used to cover the mixed bowel flora that will have leaked into the patient’s peritoneum?

Answer 3

Any of Co-amoxiclav, Piptazobactam, Ertapenem, Imipenem or Meropenem could be used alone as they are broad spectrum AND cover anaerobes.

If Cefuroxime, Ceftriaxone or Cefotaxime were used then Metronidazole would need to be added to cover the anaerobes. You would not use Cefuroxime, Ceftriaxone or Cefotaxime with Clindamycin as this poses too high a risk for Clostridium difficile associated diarrhoea (CDAD).

Question 4

How do you cover gut flora in patients who are penicillin allergic?

Answer 4

In patients with serious penicillin allergies Beta-lactams including Co-amoxiclav, Piptazobactam, Ertapenem, Imipenem or Meropenem are contraindicated.

Combinations of antibiotics are therefore needed to cover the gut flora, such as Teicoplanin OR Vancomycin (which only have Gram-positive activity) PLUS Metronidazole (which only covers anaerobes) PLUS either Ciprofloxacin OR Gentamicin (both of which have excellent Gran-negative activity)

Question 5

What antibiotics cover pseudomonas species?

Answer 5

Piperacillin/ Tazobactam (Tazocin)
Ceftazidime
Imipenem
Meropenem
Gentamicin
Amikacin
Tobramycin
Ciprofloxacin (only agent available orally as well as IV)
Colistrin
Aztreonam

Question 6

Why are multiple antipseudomonas abx used in CF patients?

Answer 6

To prevent resistance

Question 7

Which antibiotics are active ONLY against gram positive bacteria?

Answer 7

Vancomycin
Teicoplanin
Linezolid
Daptomycin

Question 8

Which antibiotics are active against ONLY gram negative bacteria?

Answer 8

Ceftazidime
Colistrin
Aztreonam

Question 9

What antibiotics are active against “non-culturable” bacteria?

Answer 9

Erythromycin
Clarithromycin
Azithromycin
Ciprofloxacin
Levofloxacin
Doxycycline