antibioticsbooks

64 PART 2 Antibacterial Drugs
Adverse Effects
Similar to those of other beta-lactams.
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Important Facts
• These drugs retain the Gram-positive activity
of penicillin and are active against many streptococci
and enterococci.
• Antipseudomonal penicillins can be used by
themselves or, more commonly, in combination
with a beta-lactamase inhibitor (see the next
section).
• Piperacillin is the most frequently prescribed of
these agents. It has stronger antipseudomonal
activity than ticarcillin. Carbenicillin may be
administered orally, but it does not achieve useful
concentrations for the treatment of anything
except UTIs. Mezlocillin is not commonly used.
What They’re Good For
Infections caused by susceptible Pseudomonas or
other GNRs. If a Gram-positive organism is susceptible
to an antipseudomonal penicillin, it will
be susceptible to at least one narrower-spectrum
penicillin as well, and the narrower-spectrum drug
should generally be used.
Don’t Forget!
These drugs are useful step-down agents in the
treatment of infections caused by Pseudomonas
aeruginosa. However, they are not good empiric
therapeutic choices, because other GNRs that cause
nosocomial infections are often resistant to them
(such as E. coli) due to beta-lactamase production.
Start with a beta-lactamase-resistant agent, then
change your therapy to an antipseudomonal penicillin
if susceptibilities allow.