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Toronto Notes 2019
Antimicrobials
Infectious Diseases ID49
Table 31. Antibiotics
Class and Drugs
CELL WALL INHIBITORS
Penicillins
Benzyl penicillin
- penicillin G IV/IM - penicillin V PO
Aminopenicillin
- ampicillin IV
- amoxicillin PO (Amoxil®)
Isoxazyolyl penicillin - cloxacillin
- methicillin
- nafcillin
- oxacillin
β-lactam/β-lactamase inhibitor combinations
- amoxicillin-clavulanate (Clavulin®, Augmentin®)
- piperacillin/tazobactam (Tazocin®)
Cephalosporins
Coverage
GP except Staphylococcus, Enterococcus,
N. meningitidis,
Oral anaerobes
Syphilis
Same as penicillin AND
Enterococcus Listeria
Some strains of: H. influenzae,
E. coli,
K. pneumoniae
Methicillin-sensitive Staphylococcus aureus; streptococci
Same as penicillin AND
Staphylococcus
H. influenzae Enterococcus Anaerobes (oral and gut)
Mechanism of Action
Bactericidal: β-lactam inhibits cell wall synthesis by binding penicillin binding protein (PBP) preventing cross- linking of peptidoglycan
See above
See above
β-lactamase prduced by certain bacteria inactivate β-lactams Lactamase inhibitors prevent this process, preserving antibacteral effect of β-lactams
Bactericidal: β-lactam inhibits PBP, prevents cross- linking of peptidoglycan, less susceptible to penicillinases
See above
See above
See above
Adverse Effects
Immediate allergy (IgE): anaphylaxis, urticaria
Late-onset allergy (IgG): urticaria, rash, serum sickness Interstitial nephritis Dose related toxicity: seizures
Diarrhea See above
See above
See above
10% penicillin allergy cross-reactivity
See above
~1% penicillin allergy cross- reactivity
See above
Indications
Mild to moderately severe infections caused by susceptible organisms including: actinomycosis, streptococcal pharyngitis, streptococcal
skin and soft tissue infections, pneumococcal pneumonia, syphilis
Bacterial meningitis and endocarditis (IV ampicillin), acute otitis media (AOM), streptococcal pharyngitis, sinusitis, acute exacerbations of COPD, part
of multidrug therapy for H.
pylori treatment, Lyme disease, pneumococcal pneumonia; UTI (amoxicillin and ampicillin) for most enterococci and susceptible gram-negative pathogens
Bacterial infections caused by staphylococci and streptococci including skin and soft-tissue infections
Various β-lactamase producing bacteria, Clavulin® sensitive bacteria including RTI, sinusitis, AOM, skin and soft tissue infections, UTI, and severe intra- abdominal and pelvic infections
Skin and soft tissue infections, prevention of surgical site infections (cefazolin); infections caused by susceptible organisms (especially Staph and Strep infections)
Upper and lower respiratory tract infections; pneumococcal pneumonia; soft tissue infections
Community-acquired pneumonia (cefotaxime, ceftriaxone), gonorrhea (use ceftriaxone), community-acquired bacterial meningitis (ceftriaxone, cefotaxime); abdominal and pelvic infections (cefotaxime
or ceftriaxone in combination with metronidazole); once-daily administration makes ceftriaxone convenient for outpatient IV therapy
Empiric therapy for febrile neutropenia
Contraindications
Hypersensitivity to penicillin cov?
Hypersensitivity
to penicillin or β-lactam antibiotics
Hypersensitivity to cloxacillin or any penicillin
Hypersensitivity
to penicillin or cephalosporin History of Clavulin®- associated jaundice or hepatic dysfunction
Hypersensitivity to cephalosporins or other β-lactam antibiotics
See above
Severe hypersensitivity (Type I) to other β-lactam antibiotics
See above
PO
1° cephalexin (Keflex®)
2° cefuroxime (Ceftin®) cefprozil (Cefzil®)
3° cefixime (Suprax®)
4°
IV
cefazolin (Ancef®)
cefuroxime (Zinacef®) cefoxitinA
ceftriaxone (Rocephin®) cefotaxime (Claforan®) ceftazidimeB (Fortaz®)
cefepime (Maxipine®)
GP
Good with the exception of Enterococcus and MRSA
Weaker activity than 1°
S. aureus + streptococcal coverage (cefotaxime and ceftriaxone) especially S. pneumoniae
Broad spectrum
GN
E. coli, Klebsiella, Proteus, H. influenzae
(not all isolates)
More coverage than 1° (Aincludes anaerobes)
Broad coverage (Bincludes Pseudomonas for ceftazidime only)
Broad coverage including Pseudomonas