Empiric antibiotic treatment of infectious disease syndromes

Question 1

Respiratory tract cluster of ‘bugs’

Answer 1

• Pneumococcus
• Hemophilus influenzae
• Moraxella catarrhalis
• Meningococcus
• Chlamydophila pneumoniae
• Mycoplasma pneumonaie
• Group A streptococcus

Question 2

What are the common respiratory tract syndromes?

Answer 2

• Otitis media
• sinusitis
• pharyngitis
• pneumonia
• meningitis

Question 3

Intra-abdominal cluster of ‘bugs’:

Answer 3

• Gram negative aerobic bacill
• anaerobes
• enterococci

Question 4

What are the common intra-abdominal syndromes?

Answer 4

• diverticulitis
• intra-abdominal abscess/peritonitis
• cholecytitis
• pylonephritis
• pelvic inflammatory disease
• diabetic foot infection

Question 5

What are the skin ‘bugs’?

Answer 5

• Group A streptococcus

- Staphylococcus aureus

Question 6

What are the common skin syndromes?

Answer 6

• cellulitis
• erysipelas
• abscess

Question 7

What are the major antibiotic ‘families’ and individual antibiotics that you need to know?

Answer 7

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)

Question 8

What are the main 2 families for inpatients and 2 main families for outpatients?

Answer 8

• outpatients: macrolides, tetracyclines

- inpatients: carbapenems, aminoglycosides

Question 9

Match the AB to the bacteria:
Penecillins:
1. Pen
2. Amp/Amox
3. Clox

Answer 9

1. Pen: Strepto, pneumo-cocci
2. Amp/Amox: enterococci
3. Clox: Staph aureus

Question 10

Match the AB to the bacteria:

1. Cephalosporins (1)
2. Ceph (2)
3. Ceph (3)

Answer 10

by generation:

1. Ceph (1): Staph aureus
2. H flu or pneumococcus (resp)
3. Pneumococcus and GN (GC, meningococcus, H flu)

Question 11

Match AB to bacteria:

Fluoroquinolones

Answer 11

GN (cipro) and resp tract (Levo, moxi).

Question 12

Match AB to bacteria:

macrolides (azithromycin, clarithromycin):

Answer 12

• Group A strep, pneumococcus, Staph aureus (if penicillin allergy)
• Resp tract infx
• Traveler’s diarrhea or Chlamydia (Azithro)

Question 13

What ABs are used on really sick patients with resistant organisms?

Answer 13

• Vancomycin (GP: MRSA, Enterococcus)
• Aminoglycosides (GN aerobes)
• Carbapenems or Pip-Tazo (v. broad spectrum)

Question 14

What AB is used for anaerobes (esp intra-abdominal)?

Answer 14

metronidazole

Question 15

What AB is used for anaerobes for above the DIA and some GP?

Answer 15

Clindamycin

Question 16

What ABs are used for cystitis?

Answer 16

Trimethoprim-sulfamethoxazole or nitrofurantoin

Question 17

What AB is used for Clamydia (urethritis/PID) and respiratory tract infections?

Answer 17

Doxycline

Question 18

What do you need to consider when choosing an empiric AB?

Answer 18

• 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

Question 19

What drugs would you use for purulent tonsillitis?

Answer 19

think: Strep Pyogenes (versus: viruses like EBV)

RX:
Penicillin, Cephalosporin (1st gen), Macrolide

Question 20

What drugs would you use for cellulitis?

Answer 20

Think: streptococcus pyogenes (Group A) or Staphylococcus aureaus

Rx:
1st Gen Cephalosporin
Cloxacillin
Clindamycin, Macrolide, Respiratory fluoroquinalone

Question 21

What drugs would you use to rx septic monoarthritis?

Answer 21

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

Question 22

Rx for acute otitis media?

Answer 22

think: strep pneumoniae, hemophilus influenzae, moraxella catarrhalis , viruses

Rx:
amoxicillin, cephalosporin (2nd/3rd), clarithromycin, azithromycin

Question 23

Rx for cyctitis (lower, uncomplicated UTI)?

Answer 23

think: E. coli, GN aerobic bacilli, staph saprophyticus
rx: trimethoprim-sulfamethoxazole, nitrofurantoin, ciprofloxacin (if severe)

Question 24

Rx for intra-abdominal sepsis?

Answer 24

think: GN aerobic bacilli, anaerobes (esp B. fragilis)

rx:
GN aerobic:
-source control
-cephalosporin, aminoglycosides, ciprofloxacin

GN anaerobic:
metronidazole

meropanem, piperacillin-tazobactam

Question 25

Rx for meningitis?

Answer 25

think: Spneumoniae, H influenzae, meningococcus, listeria

rx:
ceftriaxone (3rd gen ceph), vancomycin, ampicillin

Question 26

What score is used to assess the severity of pneumonia?

Answer 26

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

Question 27

Rx for CAP (pneumonia, CURB-65 =0 )?

Answer 27

think: S. pneumoniae, H. influenzae , mycoplasma pneumonaie, chlamydophila pneumoniae, legionella

rx:
macrolide+beta-lactam, doxycycline, RFQ (levofloxacin, moxifloxacin)

Question 28

Why should you avoid a respiratory fluoroquinalone (RFQ) with mild disease (pneumonia)?

Answer 28

• it is broad spectrum–> C diff high risk

- overuse may lead to resistance

Question 29

If macrolide-resistance to pneumococcus is >25%, what should you add to macrolide rx?

Answer 29

beta-lactam

note: macrolide-resistance in Toronto: 28%

Question 30

Rx for traveler’s diarrhea?

Answer 30

think: GN aerobic bacteria: salmonella, shigella, campylobacter, yersinia entrocolitica, e.coli

rx:
- fluoroquinolone (or azithromycin)