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

Abstract

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.

The role of adjunctive antibiotics in the treatment of skin and soft tissue abscesses: a systematic review and meta-analysis

“…7,9,11 In the remaining two trials, adherence with therapy was generally poor. 8,10 We noted a wide range in reported rates of treatment failure between trials (median 4.1%, range 0% − 17% in the antibiotic group and median 5.3%, range 3.7% − 26.5% in the no antibiotic group). Details of the included RCTs are presented in Table 2.…”

“…The majority suffered from incomplete outcome data due to high lost to follow-up rates. [8][9][10][11] Additional sources of bias were inclusion of patients on antibiotics prior to enrollment, 7 and use of beta-lactam antibiotics despite a high rate of CA-MRSA in the study population. 9 Four of the RCTs were placebo-controlled.…”

“…9 Four of the RCTs were placebo-controlled. [8][9][10][11] Treatment failure was defined as the need for repeat incision and drainage and/or need for antibiotics, except in one trial where it was defined as persistent infection. 8 Adherence with therapy was not assessed in three trials.…”

“…[8][9][10][11] Treatment failure was defined as the need for repeat incision and drainage and/or need for antibiotics, except in one trial where it was defined as persistent infection. 8 Adherence with therapy was not assessed in three trials. 7,9,11 In the remaining two trials, adherence with therapy was generally poor.…”

“…2,3,[7][8] Although most RCTs demonstrate no benefit, a few show a trend toward benefit, 7,11 and some authors have argued that these studies were underpowered to show a benefit that likely exists. 9 A 2007 systematic review and 2013 meta-analysis found no benefit from adjunctive antibiotics.…”