Vancomycin
Vancomycin (& Coag negative staph)
Coagulase-negative staphylococci (eg, Staphylococcus epidermidis) are
responsible for the majority of catheter-related infections. These infections
are particularly difficult to treat because coagulase-negative staphylococci
usually are resistant to multiple drugs and are predictably susceptible only to
vancomycin.
Vancomycin, a glycopeptide
antibiotic, is selectively
bactericidal against most gram-positive organisms, but has almost no
activity against gram-negative organisms. At therapeutic serum levels,
vancomycin
is only bacteriostatic
for enterococci;
combination therapy with an
aminoglycoside should be used
when treating serious
enterococcal infections.
Several mechanisms of antimicrobial activity have been described for vancomycin,
the primary one being interference with
cell wall synthesis. Because vancomycin and beta-lactam antibiotics act
at different sites and stages of cell wall synthesis, no cross-resistance
occurs.
Vancomycin is not absorbed well following oral administration and should be
administered intravenously except for the treatment of Clostridium difficile
colitis.
Vancomycin is the drug of choice for treating various infections, including
endocarditis
caused by methicillin-resistant
S aureus
and coagulase-negative
staphylococci. Coagulase-negative staphylococcal
infections generally occur in the context of a
foreign body, such as an
indwelling catheter or a prosthetic device, and frequently are encountered in
preterm infants and oncology patients who have fever and neutropenia. Vancomycin
also is indicated for infections caused by other resistant gram-positive
pathogens.
Long a problem in many parts of the world,
S
pneumoniae
resistance to penicillin and other antimicrobial agents, including
third-generation cephalosporins,
is increasing dramatically in the United States.
Many experts suggest a combination of a
third-generation cephalosporin and
vancomycin
as the initial therapy for suspected bacterial meningitis, at least until
sensitivities are available, particularly in areas where resistant strains of
pneumococci
have been identified.
During the past decade, vancomycin-resistant
enterococci
have emerged rapidly as
nosocomial pathogens at
hospitals throughout the United States. Most recently, strains of S aureus with
intermediate resistance to vancomycin and other glycopeptides also have been
reported. The major risk factor for emergence of both vancomycin-resistant
enterococci and S aureus with reduced susceptibility to vancomycin has been the
increased use of vancomycin, particularly among patients on the
hematology-oncology, neonatology, cardiac surgery, and neurosurgery services.
Prevention of further vancomycin resistance depends on appropriate use of this
drug.
Situations in which the use of
vancomycin
is suitable include the following:
• treatment of serious infections due to
beta-lactam-resistant
gram-positive organisms;
• treatment of infections due to gram-positive microorganisms in patients who
have serious allergy to beta-lactam
agents;
• failure of antibiotic-associated
colitis to respond to
metronidazole therapy or
colitis that is severe and potentially life-threatening;
• prophylaxis, as recommended by
the American Heart Association, for
endocarditis following
certain procedures in patients at high risk for endocarditis;
• prophylaxis for major surgical
procedures involving implantation of
prosthetic materials or devices at institutions that have a high rate of
infections due to methicillin-resistant S aureus or methicillin-resistant
coagulase-negative staphylococci.
Major adverse reactions associated with vancomycin use include ototoxicity,
nephrotoxicity, and "red man syndrome."
Nephrotoxicity and
ototoxicity
have been associated with high serum levels of
vancomycin, although there have
been fewer reactions with the newer and more purified preparations.
Unfortunately, the data supporting a
cause-and-effect relationship between serum levels of the drug and either its
efficacy or its reported toxicities are not very convincing, and some experts
advocate abandoning the practice of monitoring serum
vancomycin
levels.
"Red man" or "red neck" syndrome
is an immediate reaction to rapid
infusion of vancomycin
that is caused by acute systemic
nonimmunologically mediated
histamine release. Symptoms include pruritus; an erythematous rash
generally involving the face, neck, and upper torso; and in
rare instances, hypotension and
cardiovascular collapse. "Red man" syndrome may be seen during or soon
after completion of vancomycin infusion. The reaction is not a contraindication
to the continuation of vancomycin; it can be avoided by slowing the infusion
rate and administering antihistamines prior to the infusion.
Cephalothin,
clindamycin,
or nafcillin is an
appropriate choice for treatment of S aureus infections in a setting in which
methicillin resistance is rare, but these antibiotics
would not provide sufficient coverage
against coagulase-negative
staphylococci, which usually are resistant.
Penicillin G would not provide adequate
coverage for either S aureus
or coagulase-negative
staphylococci because both may produce
beta-lactamase,
an enzyme that disrupts the beta-lactam
ring.
References:
American Academy of Pediatrics. Principles of judicious use of
vancomycin. In: Pickering LK, ed. 2000 Red Book: Report of the
Committee on Infectious Diseases. 25th ed. Elk Grove Village, Ill:
American Academy of Pediatrics; 2000:649-650
Cantu TG, Yamanaka-Yuen NA, Lietman P. Serum vancomycin
concentrations: reappraisal of their clinical value. Clin Infect Dis.
1994;18:533-543
Centers for Disease Control and Prevention. Recommendations for
preventing the spread of vancomycin resistance. Recommendations of the
Hospital Infection Control Practices Advisory Committee. MMWR Morb
Mortal Wkly Rep. 1995;44(RR-12):1-13
Goldman DL. Vancomycin. Pediatr Rev. 1995;16:357-358
Wilhelm MP. Vancomycin. Mayo Clin Proc. 1991;66:1165-1170