Prevalence of Methicillin Resistant Staphylococcus aureus in Upper Extremity Soft Tissue Infections

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Prevalence of Methicillin ResistantStaphylococcus
aureus inUpper Extremity Soft Tissue
Infectionsat Jackson Memorial Hospital,Miami-Dad
e County, Florida

• Jodie A. Barkin, BA, Roberto A. Miki, MD,
• Zakariah S. Mahmood, MD, David C. Landy, MPH,
• and Patrick W. Owens, MD
• Department of Orthopaedics, University of
  Miami, Miller School of Medicine, Miami, FL
• Medical Student, University of Miami, Miller
  School of Medicine, Miami, FL

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PRESENTER DISCLOSURE

• No author involved in this study received
  anything of value from, or own stock (or stock
  options) in a commercial company or institution
  related directly or indirectly to the subject of
  this presentation. 

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INTRODUCTION AIM

• Recent increases in outpatient Methicillin
  Resistant Staphylococcus aureus (MRSA)
  infections suggest there may be increased
  incidence of MRSA in Upper Extremity Soft Tissue
  Infections (UESTIs).
• AIM To determine the current microbial flora
  found in upper extremity soft tissue infections
  seen at Jackson Memorial Hospital.

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METHODS

• Retrospective chart review of all orthopaedic
  consultations for suspected UESTIs from June,
  2006 to December, 2007 at Jackson Memorial
  Hospital.
• Osteomyelitis was the only exclusion criterion.
• STATISTICAL ANALYSIS Logistic regression
  performed to identify if any of the variables
  identified on univariate analysis at plt0.05, were
  significantly associated with a MRSA positive
  culture. Odds ratios with 95 confidence
  intervals are reported. Variables examined on
  univariate analysis included age, gender,
  infection location, diagnosis, WBC, ESR, and CRP.

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METHODS 2

• POPULATION There were 432 orthopaedic
  consultations for UESTIs performed at Jackson
  Memorial Hospital during the study period.
• Twelve cases of osteomyelitis were excluded per
  protocol.
• 420 patients comprised the study population,
  ranging in age from 4 months to 95 years, (mean
  of 40 years), with 327 (77.9) men and 93 (22.1)
  women.

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RESULTS

• Wound cultures in 335 of 420 patients (79.8)
• Positive cultures in 292 of 335 patients (87.2)
• MRSA positive in 156 of 292 patients (53.4)
• Methicillin Sensitive Staphylococcus aureus
  (MSSA) was the second most prevalent microbe
  found in 73 of 292 patients (25.0).
• 48 patients had positive cultures for more than
  one bacteria.
• All MRSA isolates were sensitive to gentamicin
  and linezolid and 98 were sensitive to
  vancomycin, rifampin, and trimethoprim-sulfamethox
  azole combination.

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Microbe Cultured
MICROBIAL ISOLATES FROM WOUND CULTURE
Number of Positive Cultures
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RESULTS 2

• 58.9 (175 of 399) of infections in the dominant
  upper extremity.
• The finger was the most common site of infection
  at 50.2 (210 of 419) of patients.
• Infection location proximal to the wrist was
  significantly associated with a MRSA positive
  culture (OR1.81, 95C.I.1.06-3.09, p0.03).
• The most common presentation of UESTIs was an
  abscess, found in 256 of 420 patients (61.0).
• Diagnoses of abscess and felon (abscess of the
  fingertip pulp) were significantly associated
  with MRSA positive culture (OR3.22,
  95C.I.1.84-5.63, plt0.001).

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CONCLUSIONS

• This is the largest study (420 patients)
  examining the prevalence of microbial flora in
  UESTIs.
• MRSA is now the most common microbe in UESTIs
  comprising 53.4 of isolates. MRSA is
  significantly associated if the infection is
  proximal to the wrist, or diagnosed as abscess or
  felon.

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CONCLUSIONS 2

• Our results are comparable to Bach et als1
  reporting of 52 patients with a 73 (38 patients)
  MRSA rate in hand infections, Moran et als2 63
  MRSA rate in generalized skin and soft tissue
  infections (SSTIs), and in contrast to Weinzweig
  et als study from 1992-1995 showing only 16.2
  of SSTIs were MRSA positive3.
• The bacterial shift to MRSA necessitates careful
  monitoring, vigilance, and treatment by
  healthcare professionals.

1 Bach et al J Hand Surg 2007 32A 380-83. 2
Moran et al. NEJM 2006 355 666-74. 3 Weinzweig
et al. Ann Plast Surg 2002 49(6) 621-27.