antibioticsbooks

60 PART 2 Antibacterial Drugs
Adverse Effects
Similar to those of other beta-lactams. Aminopenicillins
have a high incidence of diarrhea when
given orally.
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Important Facts
• Though ampicillin can be given orally, amoxicillin
is a better choice. It is more bioavailable,
better tolerated, and administered less
frequently. Use ampicillin for IV therapy, and
amoxicillin for oral therapy. Europeans disagree;
they use amoxicillin intravenously also.
• Ampicillin is a drug of choice for susceptible
enterococci.
• These drugs are often listed as alternative
regimens for UTIs in pregnant women because
they are pregnancy category B and eliminated
renally. However, resistance in E. coli to them
is very high and susceptibility testing should
be performed.
What They’re Good For
Infections caused by susceptible GNRs, enterococci,
and streptococci. Because resistance among
GNRs is prevalent, aminopenicillins are used only
infrequently in complicated nosocomial infections.
Amoxicillin is frequently prescribed for infections
of the upper respiratory tract, including streptococcal
pharyngitis (strep throat) and otitis media
(ear infection).