Lack of Antibiotic Efficacy for Simple Abscesses: Have Matters Come to a Head?

Antibiotics for the Treatment of Staphylococcal Infections in the Obstetric Patient

This review addresses current epidemiology and treatment of obstetric staphylococcal infections. It also examines current prophylaxis methods and the efficacy of universal screening.

Trimethoprim-Sulfamethoxazole versus Placebo for Uncomplicated Skin Abscess

BACKGROUND

U.S. emergency department visits for cutaneous abscess have increased with the emergence of methicillin-resistant Staphylococcus aureus (MRSA). The role of antibiotics for patients with a drained abscess is unclear.

METHODS

We conducted a randomized trial at five U.S. emergency departments to determine whether trimethoprim-sulfamethoxazole (at doses of 320 mg and 1600 mg, respectively, twice daily, for 7 days) would be superior to placebo in outpatients older than 12 years of age who had an uncomplicated abscess that was being treated with drainage. The primary outcome was clinical cure of the abscess, assessed 7 to 14 days after the end of the treatment period.

RESULTS

The median age of the participants was 35 years (range, 14 to 73); 45.3% of the participants had wound cultures that were positive for MRSA. In the modified intention-to-treat population, clinical cure of the abscess occurred in 507 of 630 participants (80.5%) in the trimethoprim-sulfamethoxazole group versus 454 of 617 participants (73.6%) in the placebo group (difference, 6.9 percentage points; 95% confidence interval [CI], 2.1 to 11.7; P=0.005). In the per-protocol population, clinical cure occurred in 487 of 524 participants (92.9%) in the trimethoprim-sulfamethoxazole group versus 457 of 533 participants (85.7%) in the placebo group (difference, 7.2 percentage points; 95% CI, 3.2 to 11.2; P<0.001). Trimethoprim-sulfamethoxazole was superior to placebo with respect to most secondary outcomes in the per-protocol population, resulting in lower rates of subsequent surgical drainage procedures (3.4% vs. 8.6%; difference, -5.2 percentage points; 95% CI, -8.2 to -2.2), skin infections at new sites (3.1% vs. 10.3%; difference, -7.2 percentage points; 95% CI, -10.4 to -4.1), and infections in household members (1.7% vs. 4.1%; difference, -2.4 percentage points; 95% CI, -4.6 to -0.2) 7 to 14 days after the treatment period. Trimethoprim-sulfamethoxazole was associated with slightly more gastrointestinal side effects (mostly mild) than placebo. At 7 to 14 days after the treatment period, invasive infections had developed in 2 of 524 participants (0.4%) in the trimethoprim-sulfamethoxazole group and in 2 of 533 participants (0.4%) in the placebo group; at 42 to 56 days after the treatment period, an invasive infection had developed in 1 participant (0.2%) in the trimethoprim-sulfamethoxazole group.

CONCLUSIONS

In settings in which MRSA was prevalent, trimethoprim-sulfamethoxazole treatment resulted in a higher cure rate among patients with a drained cutaneous abscess than placebo. (Funded by the National Institute of Allergy and Infectious Diseases; ClinicalTrials.gov number, NCT00729937.).

Management and outcome of adults with skin and soft tissue infection caused by methicillin-resistant Staphylococcus aureus in a tertiary hospital in central Taiwan

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) has been increasingly causing skin and soft tissue infections (SSTIs). Only limited studies have made comparisons between incision and drainage (I&D) alone and I&D with adjunctive antibiotic therapy for treatment effects, and most of the studies were conducted before the emergence of MRSA. This study was to evaluate whether antibiotics provide added benefit to I&D alone for purulent MRSA SSTIs.

METHODS

This retrospective study collected data on SSTI patients, including patient demographics, treatment strategies, antibiotic susceptibilities of the infecting MRSA isolates, and clinical outcomes over the course of 24 months.

RESULTS

Antimicrobial drug susceptibility rate were 100% for vancomycin, teicoplanin, and linezolid. Among the 211 patients, 7.6% were treated solely with I&D (Group A), 62.6% were treated via I&D with adjunctive antibiotic (Group B), and 29.8% patients received only antibiotics (Group C). The cure rate was highest in Group A (93.8%), followed by Group B (90.9%) and Group C (77.8%). Combining Group B and Group C, patients who were treated appropriately demonstrated a higher cute rate (91.3% vs. 75.4%, p = 0.005). Multivariate analysis showed that Group B was more likely to be successfully treated compared to Group C (odds ratio = 2.51, 95% confidence interval = 1.01-6.25, p = 0.047), whereas no difference between Group A and Group B was found (odds ratio = 2.09, 95% confidence interval = 0.20-22.34, p = 0.542, data not shown).

CONCLUSION

Surgical intervention is the definitive therapy for purulent SSTIs. Adjunctive antibiotic therapy increased the cure rate and appropriateness of prescription is influential.

Changes in prescriptive practices in skin and soft tissue infections associated with the increased occurrence of community acquired methicillin resistant Staphylococcus aureus

BACKGROUND

Over 30% of the US population is colonized with methicillin resistant Staphylococcus aureus (MRSA). People within the community, without factors associated with Hospital Acquired (HA) MRSA, present with skin and soft tissue infections (SSTIs). Community Acquired MRSA (CA-MRSA) is resistant to antibiotics typically prescribed for SSTI. Many SSTIs are treated with antibiotics that are ineffective against drug resistant strains.

STUDY OBJECTIVES

This study examines the incidence of SSTIs associated with CA-MRSA, to determine if an increase in SSTI's is associated with changes in prescribing patterns for MRSA.

METHODS

A secondary analysis of the National Ambulatory Medical Care Survey (NAMCS) and National Hospital Ambulatory Medical Care Survey (NHAMCS) data was used to detect incidence of SSTIs based on ICD-9 coding between the periods of 1997-2002 and 2003-2008. Antibiotic prescribing patterns were examined for treatment.

RESULTS

Incidence of SSTIs increased by 84.7% from 1997-2002 to 2003-2008. Antibiotics prescribed for methicillin sensitive S. aureus decreased while treatment with MSRA antibiotics increased.

CONCLUSION

There is an increased incidence of SSTI within the community, suggesting that CA-MRSA may be a contributing factor. Health care providers are recognizing the increased incidence of CAMRSA, and are treating SSTI with appropriate antibiotics.

Emergency department visit rates for abscess versus other skin infections during the emergence of community-associated methicillin-resistant Staphylococcus aureus, 1997-2007

Due to a flaw in the International Classification of Diseases, Ninth Revision, Clinical Modification coding system, epidemiology of skin and soft-tissue infections (SSTIs) has conflated abscess with other SSTIs. We analyzed emergency department visits during 1997-2007, finding that the odds of abscess relative to any other diagnosis increased 11% per year, or 3.1-fold, whereas other SSTIs increased minimally.

Skin and soft-tissue infections in suburban primary care: epidemiology of methicillin-resistant Staphylococcus aureus and observations on abscess management

BACKGROUND

Reports from urban medical centers suggest that methicillin-resistant Staphylococcus aureus (MRSA) has become the most common cause of skin and soft-tissue infections (SSTIs). Risk factors for MRSA have been identified but have not been clinically useful.

FINDINGS

From May 2006-April 2007, we performed an observational study of 529 SSTIs among ambulatory patients in the urgent care departments of a large suburban primary-care practice. SSTIs were included if they produced pus or fluid. The proportion of MRSA was determined overall (defined as prevalence) and by SSTI diagnosis. Potential risk factors for MRSA were examined with multivariate analysis, and descriptive statistics were generated for follow-up and abscess management. The prevalence of MRSA was 22% and did not rise during the study. MRSA was isolated from 36% of abscesses, 15% of cellulitis, and 14% of other SSTIs. Independent risk factors for MRSA included a prior history of MRSA (adjusted odds ratio [aOR], 41.05; 95% confidence interval [CI], 11.4-147.3), a close contact with prior MRSA (aOR, 12.83; 95% CI, 4.2-39.2), erythema ≥10 cm (aOR, 2.59; 95% CI, 1.5-4.4), and abscess diagnosis (aOR, 3.19; 95% CI, 2.1-5.0). Prior MRSA had a positive predictive value of 88% for current MRSA. When both abscess diagnosis and erythema ≥10 cm were present, the proportion of MRSA was 59%. The vast majority of SSTIs (96 percent) resolved or improved within one week. Most abscesses, even small ones, were treated with antibiotics. Resource utilization was highest in those abscesses with erythema ≥10 cm.

CONCLUSIONS

The prevalence of MRSA is relatively low among SSTIs in suburban primary care. However, MRSA is common in the subgroup of abscesses with large erythema. While the effectiveness of adjunctive antibiotic therapy for large abscesses is unknown, drugs chosen for these infections should be active against MRSA. Most non-abscess SSTIs do not require treatment with a MRSA-active drug, and antibiotics are probably overused for small abscesses. A history of prior MRSA should be recorded in a patient's health record.