Drugs for Infections

Question 1

Abx for skin infections

Answer 1

Flucloxacillin 250-500mg QDS, 30min before food

Clarithromycin/clindamycin if allergic to penicillin

also - Erythromycin / doxycycline

Question 2

Abx impetigo

Answer 2

Small area: topical fusidic acid 7dys. If MRSA suspected, mupirocin

Widespread: flucloxacillin 250-500mg PO 6hrs, 30mins before food.

Question 3

Abx erysipelas

Answer 3

Benzylpenicillin - 0.6-1.2g IM/IV 6hrly

Phenoxymethylpenillin - 500mg PO 6hrly

Question 4

Abx cellulitis

Answer 4

Flucloxacillin - 500mg PO 6hrly

If streptococcal, give benzylpenicillin/pneocymethylpenicillin
G-ve give broad spectum

Question 5

Abx for C.difficile infection

Answer 5

Oral metronidazole 400-500mg every 8hrs, 10-14dys

Add vancomycin for severe infection

Question 6

Major antibiotics

Answer 6

Penicillins

Cephalosporins

Aminoglycosides

Macrolides

Quinolones

Antifolates

Metroniadazole

Question 7

Antibiotic used to target anaerobes

Answer 7

Metronidazole

Widely distributed, used to treat abscesses

Question 8

Antibiotics that inhibit cell wall synthesis

Answer 8

Penicillins (benzylpenicillin, flucoxacaillin, amoxicillin mainly gram +ve activity)

Cephalosporins (gram -ve)

Carbapenems (gram +ve)

Vancomycin IV (gram +ve)

Question 9

Antibiotics that inhibit protein synthesis

Answer 9

Aminoglyclosides (gram -ve) e.g. gentamicin IV

Macrolides (gram +ve) e.g. erythromycin

Tetracyclins

Question 10

Likely 1st line antibiotic in skin infections

Answer 10

Most caused by S. aureus - Flucloxacillin

Not inactivated by penicillinase enzymes.

Question 11

Likely 1st line antibiotic in LRTI

Answer 11

Amoxycillin

Cause likely to be S. pneumoniae

Question 12

likely 1st line antibiotic for bacterial meningitis

Answer 12

Ceftriaxone IV

Vancomycin in penicillin allergy

Caused by S. pneumoniae, N. meningitidis, H. influenzae

Question 13

Treatment for uncomplicated UTI

Answer 13

Trimethoprim

organism - E coli

Question 14

Abx in hospital acquired pneumonia

Answer 14

Co-amoxiclav

Question 15

Abx in community acquired pneumonia

Answer 15

Mild/moderate: Amoxicillin, add clarithromycin if atypicals suspected.

Severe: benzylpenicillin + clarithromycin/doxycycline

Give for 7-10 days.

If MSRA suspected - vancomycin

Question 16

Adverse effects of penicillins

Answer 16

Hypersensitivity reactions - rashes, anaphylaxis. Higher risk in patients with atopy.

Note: history of a minor-rash (non-pruritic, non-confluent, small area) 72hrs post-administration are not allergic. Should not withold penicillin if serious infection.

Encephalopathy - caused by cerebral irritation, Do not give intrathecally

Diarrhoea

Monitor electrolytes in patients with renal failure, most preparations contain Na+ or K+

Question 17

Abx in oral infections

Answer 17

Phenoxymethylpenicillin

Question 18

Indications for benzylpenicillin

Answer 18

Given IV/IM - inctivated by gastric enzymes, gut absorption low.

Indicated in: throat infections, otitis media, endocarditis, cellulitis, meningitis, anthrax

Contraindicated in allergy and renal impairment.

Question 19

Abx treatment for MRSA skin infections

Answer 19

Vancomycin

Doxycycline + rifampicin/fusidate

Question 20

Name 3 broad spectrum penicillins

Answer 20

Ampicillin (many organisms resitant) - 500mg 4-6hrly

Amoxycillin - 500mg TDS

Co-amoxiclav - one 250/125 tablet 8hrly

Question 21

Cautions/contraindications of broad-spectrum penicllins

Answer 21

Erythematous rash (glandular fever/CMV)

Reduce dose if patients have impaired renal function (eGFR<10). May cause crystalluria, convulsions

Co-amoxiclav - cholestatic jaundice (mainly >65)

Question 22

Anti-pseudomonal penicillins

Answer 22

Piperacillin-tazobactam

Ticarcillin-clauvonic acid

For severe pseudomonal infections aminoglycoside can be given

Question 23

Name 3 cephalosporins

Answer 23

ceftriaxone (IV)

cefotaxime

ceftazidime (IV)

cefuroxime

cefalexin

cefradine (IV)

Question 24

Name 3 carbapenems

Answer 24

imipenem

meropenem

ertapenem

Question 25

Cephalosporin used in CNS infections

Answer 25

cefotaxime

Question 26

Severe side-effect associated with cephalosporins

Answer 26

Antibiotic-associated colitis may occur with the use of broad-spectrum cephalosporins, particularly second- and third-generation cephalosporins.

Question 27

Side effects of cepahlosporins

Answer 27

Diarrhoea N+V allergic reactions cholestatic jaundice

Question 28

Uses of carbapenems

Answer 28

aerobic and anaerobic Gram-positive and Gram-negative infections Severe HAI Septicaemia HA- pneumonia intra-abdominal infections, complicated UTI

Question 29

Side effects of carbapenems

Answer 29

diarrhoea N+V headache injection-site reactions - rash, pruritis

Question 30

Name 3 tetracyclines

Answer 30

Doxycyline Minocycline Tetracycline