Empiric antibiotic treatment of infectious disease syndromes Flashcards
Respiratory tract cluster of ‘bugs’
- Pneumococcus
- Hemophilus influenzae
- Moraxella catarrhalis
- Meningococcus
- Chlamydophila pneumoniae
- Mycoplasma pneumonaie
- Group A streptococcus
What are the common respiratory tract syndromes?
- Otitis media
- sinusitis
- pharyngitis
- pneumonia
- meningitis
Intra-abdominal cluster of ‘bugs’:
- Gram negative aerobic bacill
- anaerobes
- enterococci
What are the common intra-abdominal syndromes?
- diverticulitis
- intra-abdominal abscess/peritonitis
- cholecytitis
- pylonephritis
- pelvic inflammatory disease
- diabetic foot infection
What are the skin ‘bugs’?
- Group A streptococcus
- Staphylococcus aureus
What are the common skin syndromes?
- cellulitis
- erysipelas
- abscess
What are the major antibiotic ‘families’ and individual antibiotics that you need to know?
FAMILIES:
- Penicillins (BL)-C
- Cephalosporins (BL)-C
- Fluoroquinolones-C
- Macrolides-S
- Tetracyclines
- Aminoglycosides- C
- Carbapenems (BL)-C
INDIVIDUAL AGENTS:
- Trimethoprim-sulfamethoxazole C
- Nitrofurantoin - C or S
- Metronidazole- C
- Clindamycin- s
- Vancomycin (C), Linezolid (S)
What are the main 2 families for inpatients and 2 main families for outpatients?
- outpatients: macrolides, tetracyclines
- inpatients: carbapenems, aminoglycosides
Match the AB to the bacteria: Penecillins: 1. Pen 2. Amp/Amox 3. Clox
- Pen: Strepto, pneumo-cocci
- Amp/Amox: enterococci
- Clox: Staph aureus
Match the AB to the bacteria:
- Cephalosporins (1)
- Ceph (2)
- Ceph (3)
by generation:
- Ceph (1): Staph aureus
- H flu or pneumococcus (resp)
- Pneumococcus and GN (GC, meningococcus, H flu)
Match AB to bacteria:
Fluoroquinolones
GN (cipro) and resp tract (Levo, moxi).
Match AB to bacteria:
macrolides (azithromycin, clarithromycin):
- Group A strep, pneumococcus, Staph aureus (if penicillin allergy)
- Resp tract infx
- Traveler’s diarrhea or Chlamydia (Azithro)
What ABs are used on really sick patients with resistant organisms?
- Vancomycin (GP: MRSA, Enterococcus)
- Aminoglycosides (GN aerobes)
- Carbapenems or Pip-Tazo (v. broad spectrum)
What AB is used for anaerobes (esp intra-abdominal)?
metronidazole
What AB is used for anaerobes for above the DIA and some GP?
Clindamycin
What ABs are used for cystitis?
Trimethoprim-sulfamethoxazole or nitrofurantoin
What AB is used for Clamydia (urethritis/PID) and respiratory tract infections?
Doxycline
What do you need to consider when choosing an empiric AB?
- Local resistance patterns
- Recent use of ABs
- Co-morbidities
- If the px is very sick (broad spectrum, IV)
- Cost
- Safety issues (allergy/toxicity, drug interactions)
- Tissue penetration by antibiotic
- Bactericidal vs bacteriostatic - cidal if host defense challenged: Meningitis, endocarditis, neutropenia
- Evidence from randomized trials
What drugs would you use for purulent tonsillitis?
think: Strep Pyogenes (versus: viruses like EBV)
RX:
Penicillin, Cephalosporin (1st gen), Macrolide
What drugs would you use for cellulitis?
Think: streptococcus pyogenes (Group A) or Staphylococcus aureaus
Rx:
1st Gen Cephalosporin
Cloxacillin
Clindamycin, Macrolide, Respiratory fluoroquinalone
What drugs would you use to rx septic monoarthritis?
think: staphylococcus aureus (esp if older px), Group A strep, Strep pneumoniae , gonococci (if STI risk fx’s)
rx:
Cloxacillin, 1st gen Cephalosporin , Vancomycin…if gonococci-> ceftriaxone/3rd gen ceph
Rx for acute otitis media?
think: strep pneumoniae, hemophilus influenzae, moraxella catarrhalis , viruses
Rx:
amoxicillin, cephalosporin (2nd/3rd), clarithromycin, azithromycin
Rx for cyctitis (lower, uncomplicated UTI)?
think: E. coli, GN aerobic bacilli, staph saprophyticus
rx: trimethoprim-sulfamethoxazole, nitrofurantoin, ciprofloxacin (if severe)
Rx for intra-abdominal sepsis?
think: GN aerobic bacilli, anaerobes (esp B. fragilis)
rx:
GN aerobic:
-source control
-cephalosporin, aminoglycosides, ciprofloxacin
GN anaerobic:
metronidazole
meropanem, piperacillin-tazobactam
Rx for meningitis?
think: Spneumoniae, H influenzae, meningococcus, listeria
rx:
ceftriaxone (3rd gen ceph), vancomycin, ampicillin
What score is used to assess the severity of pneumonia?
CURB-65 c=confusion u=urea >7mmol/L r= RR.30/min b=BP <90/60 65= age over 65
score:
0-1 outpatient rx
2: in-patient rx, general ward
3/4/5: in patient, ICU
Rx for CAP (pneumonia, CURB-65 =0 )?
think: S. pneumoniae, H. influenzae , mycoplasma pneumonaie, chlamydophila pneumoniae, legionella
rx:
macrolide+beta-lactam, doxycycline, RFQ (levofloxacin, moxifloxacin)
Why should you avoid a respiratory fluoroquinalone (RFQ) with mild disease (pneumonia)?
- it is broad spectrum–> C diff high risk
- overuse may lead to resistance
If macrolide-resistance to pneumococcus is >25%, what should you add to macrolide rx?
beta-lactam
note: macrolide-resistance in Toronto: 28%
Rx for traveler’s diarrhea?
think: GN aerobic bacteria: salmonella, shigella, campylobacter, yersinia entrocolitica, e.coli
rx:
- fluoroquinolone (or azithromycin)
