Chapter 129. Staphylococcal Infections (Part 13) ppsx

Chapter 129. Staphylococcal Infections
(Part 13)

Antimicrobial Therapy for Selected Settings
For uncomplicated skin and soft tissue infections, the use of oral
antistaphylococcal agents is usually successful. For other infections, parenteral
therapy is indicated.
S. aureus endocarditis is usually an acute, life-threatening infection. Thus
prompt collection of blood for cultures must be followed immediately by
empirical antimicrobial therapy. For S. aureus native-valve endocarditis, a
combination of antimicrobial agents is often used. In a large prospective study, an
SPRP combined with an aminoglycoside did not alter clinical outcome but did
reduce the duration of S. aureus bacteremia. As a result, many clinicians begin
therapy for life-threatening infections with a 3- to 5-day course of a β-lactam and
an aminoglycoside (gentamicin, 1 mg/kg IV every 8 h). If a MRSA strain is
isolated, vancomycin (30 mg/kg every 24 h, given in two equal doses up to a total
of 2 g) is recommended. Patients are generally treated for 6 weeks.
In prosthetic-valve endocarditis, surgery in addition to antibiotic therapy is
often necessary. The combination of a β-lactam agent—or, if the isolate is β-
lactam-resistant, vancomycin (30 mg/kg every 24 h, given in two equal doses up
to a total of 2 g)—with an aminoglycoside (gentamicin, 1 mg/kg IV every 8 h) and
rifampin (300 mg orally or IV every 8 h) is recommended. This combination is
used to avoid the possible emergence of rifampin resistance during therapy if only
two drugs are used.
For hematogenous osteomyelitis or septic arthritis in children, a 4-week
course of therapy is usually adequate. In adults, treatment is often more prolonged.
For chronic forms of osteomyelitis, surgical debridement is necessary in
combination with antimicrobial therapy. For joint infections, a critical component
of therapy is the repeated aspiration or arthroscopy of the affected joint to prevent
damage from leukocytes. The combination of rifampin with ciprofloxacin has
been used successfully to treat prosthetic-joint infections, especially when the

device cannot be removed. The efficacy of this combination may reflect enhanced
activity against staphylococci in biofilms as well as the attainment of effective
intracellular concentrations.
The choice of empirical therapy for staphylococcal infections depends in
part on susceptibility data for the local geographic area. Increasingly, vancomycin
(in combination with an aminoglycoside or rifampin for serious infections) is the
drug of choice for both community- and hospital-acquired infections.
The increase in community-based MRSA skin and soft tissue infections has
drawn attention to the need for initiation of appropriate empirical therapy. Oral
agents that have been effective against these isolates include clindamycin, TMP-
SMX, doxycycline, and linezolid. The antimicrobial susceptibility of isolates in
different geographic regions has varied.
Therapy for Toxic Shock Syndrome
Supportive therapy with reversal of hypotension is the mainstay of therapy
for TSS. Both fluids and pressors may be necessary. Tampons or other packing
material should be promptly removed. The role of antibiotics is less clear. Some
investigators recommend a combination of clindamycin and a semisynthetic
penicillin. Clindamycin is advocated because, as a protein synthesis inhibitor, it
reduces toxin synthesis in vitro. A semisynthetic penicillin is suggested to
eliminate any potential focus of infection as well as to eradicate persistent carriage
that might increase the likelihood of recurrent illness. Anecdotal reports document
the successful use of IV immunoglobulin to treat TSS. The role of glucocorticoids
in the treatment of this disease is uncertain at present.
Therapy for Other Toxin-Mediated Diseases
Therapy for staphylococcal food poisoning is entirely supportive. For
SSSS, antistaphylococcal therapy targets the primary site of infection.
Figure 129-4


Evidence of staphylococcal scalded-skin syndrome in a 6-year-old boy.

Nikolsk
y's sign, with separation of the superficial layer of the outer epidermal
layer, is visible.
(Reprinted with permission from LA Schenfeld et al: Images in
clinical medicine. Staphylococcal scalded skin syndrome. N Engl J Med
342:1178, 2000. © 2000 Massachusetts Medical Society. All rights reserved.)

Further Readings
Diep BA et al:
Complete genome sequence of USA300, an epidemic clone
of community-acquired meticillin-resistant Staphylococcus aureus
. Lancet
367:731, 2006 [PMID: 16517273]
Fowler VG Jr et al: Staphylococcus aureus
endocarditis: A consequence of
medical progress. JAMA 293:3012, 2005 [PMID: 15972563]
———
et al: Role of echocardiography in evaluation of patients with
Staphylococcus aureus bacteremia: Experience in 103 patients. J Am Coll Ca
rdiol
30:1072, 1997
Fridkin SK et al: Methicillin-resistant Staphylococcus aureus
disease in
three communities. N Engl J Med 352:1436, 2005 [PMID: 15814879]
Grundmann H et al: Emergence and resurgence of meticillin-
resistant
Staphylococcus aureus as a public-
health threat. Lancet 368:874, 2006 [PMID:
16950365]

Lowy FD: Antimicrobial resistance: The example of
Staphylococcus
aureus. J Clin Invest 111:1265, 2003 [PMID: 12727914]
McCormick JK et al: Toxic shock syndrome and bacterial superantigens:
An update. Annu Rev Microbiol 55:77, 2001 [PMID: 11544350]
Moran GJ et al: Methicillin-resistant S. aureus
infections among patients in
the emergency department. N Engl J Med 355:666, 2006 [PMID: 16914702]
Mylotte JM, Tayara A: Staphylococcus aureus bacte
remia: Predictors of
30-
day mortality in a large cohort. Clin Infect Dis 31:1170, 2000 [PMID:
11073748]
Seybold U et al: Emergence of community-associated methicillin-
resistant
Staphylococcus aureus USA300 genotype as a major cause of health care–
associated blood stream infections. Clin Infect Dis 42:647, 2006 [PMID:
16447110]
Bibliography
Lowy FD: Staphylococcus aureus
infections. N Engl J Med 339:520, 1998
[PMID: 9709046]
Hiramatsu K et al: The emergence and evolution of methicillin-
resistant
Staphylococcus aureus. Trends Microbiol 9:486, 2001 [PMID: 11597450]
Ing MB et al: Bacteremia and infective endocarditis: Pathogenesis,
diagnosis, and complications, in The Staphylococci in Human Disease,
KB
Crossley, GL Archer (eds). New York, Churchill Livingstone, 1997, pp 331–354
von Eiff C et al: Pathogenesis of infections due to coagulase-

negative
staphylococci. Lancet Infect Dis 2:677, 2002