Epidemiology and Outcomes of Community-Associated Methicillin-Resistant Staphylococcus aureus Infection

• Published in: Journal of Clinical Microbiology Vol. 45; no. 6; pp. 1705 - 1711
• Main Authors: Davis, S.L, Perri, M.B, Donabedian, S.M, Manierski, C, Singh, A, Vager, D, Haque, N.Z, Speirs, K, Muder, R.R, Robinson-Dunn, B, Hayden, M.K, Zervos, M.J
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for Microbiology 01.06.2007
• Subjects: Anti-Bacterial Agents - pharmacology; Anti-Bacterial Agents - therapeutic use; Bacteremia - drug therapy; Bacteremia - epidemiology; Bacteremia - microbiology; Bacteriology; Biological and medical sciences; Case-Control Studies; Community-Acquired Infections - drug therapy; Community-Acquired Infections - epidemiology; Community-Acquired Infections - microbiology; Epidemiology; Female; Fundamental and applied biological sciences. Psychology; Humans; Infectious diseases; Male; Medical sciences; Methicillin - pharmacology; Methicillin Resistance; Microbial Sensitivity Tests; Microbiology; Middle Aged; Miscellaneous; Molecular Epidemiology; Prevalence; Respiratory Tract Infections - drug therapy; Respiratory Tract Infections - epidemiology; Respiratory Tract Infections - microbiology; Risk Factors; Soft Tissue Infections - drug therapy; Soft Tissue Infections - epidemiology; Soft Tissue Infections - microbiology; Staphylococcal Infections - drug therapy; Staphylococcal Infections - epidemiology; Staphylococcal Infections - microbiology; Staphylococcal Skin Infections - drug therapy; Staphylococcal Skin Infections - epidemiology; Staphylococcal Skin Infections - microbiology; Staphylococcus aureus; Staphylococcus aureus - classification; Staphylococcus aureus - drug effects; Staphylococcus aureus - genetics; Treatment Outcome; Prognosis; Microbiology; Bacteria; Micrococcales; Micrococcaceae; Epidemiology; Staphylococcus aureus
• ISSN: 0095-1137; 1098-660X; 1098-5530
• DOI: 10.1128/JCM.02311-06

Over a 2-year period (2003 to 2005) patients with community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) and community-acquired methicillin-susceptible Staphylococcus aureus (CA-MSSA) infections were prospectively identified. Patients infected with CA-MRSA (n = 102 patients) and CA-MSSA (n = 102 patients) had median ages of 46 and 53 years, respectively; the most common sites of infection in the two groups were skin/soft tissue (80 and 93%, respectively), respiratory tract (13 and 6%, respectively), and blood (4 and 1%, respectively). Fourteen percent of patients with CA-MRSA infections and 3% of patients with CA-MSSA infections had household contacts with similar infections (P < 0.01). Among the CA-MRSA isolates, the pulsed-field gel electrophoresis (PFGE) groups detected were USA300 (49%) and USA100 (13%), with 27 PFGE groups overall; 71% of the isolates were staphylococcal chromosome cassette mec (SCCmec) type IV, 29% were SCCmec type II, and 54% had the Panton-Valentine leucocidin (PVL) gene. Among the CA-MSSA isolates there were 33 PFGE groups, with isolates of the USA200 group comprising 11%, isolates of the USA600 group comprising 11%, isolates of the USA100 group comprising 10%, and isolates of the PVL type comprising 10%. Forty-six and 18% of the patients infected with CA-MRSA and CA-MSSA, respectively, were hospitalized (P < 0.001). Fifty percent of the patients received antibiotic therapy alone, 5% received surgery alone, 30% received antibiotics and surgery, 3% received other therapy, and 12% received no treatment. The median durations of antibiotic therapy were 12 and 10 days in the CA-MRSA- and CA-MSSA-infected patients, respectively; 48 and 56% of the patients in the two groups received adequate antimicrobial therapy, respectively (P < 0.001). The clinical success rates of the initial therapy in the two groups were 61 and 84%, respectively (P < 0.001); recurrences were more common in the CA-MRSA group (recurrences were detected in 18 and 6% of the patients in the two groups, respectively [P < 0.001]). CA-MRSA was an independent predictor of clinical failure in multivariate analysis (odds ratio, 3.4; 95% confidence interval, 1.7 to 6.9). In the community setting, the molecular characteristics of the S. aureus strains were heterogeneous. CA-MRSA infections were associated with a more adverse impact on outcome than CA-MSSA infections.