Clinical Importance of Purulence in Methicillin-Resistant Staphylococcus aureus Skin and Soft Tissue Infections

Department of Pediatrics, The University of Chicago, Chicago, IL 60637, USA.
The Journal of the American Board of Family Medicine (Impact Factor: 1.85). 11/2009; 22(6):647-54. DOI: 10.3122/jabfm.2009.06.090025
Source: PubMed

ABSTRACT The so-called community-associated methicillin-resistant Staphylococcus aureus (MRSA) strains are more frequently susceptible to non-ss-lactam antibiotics (including clindamycin) than health care-associated MRSA strains. We assessed whether predictive clinical characteristics of presumptive MRSA infections can be identified to guide choice of empiric antibiotic therapy.
A clinical syndrome was assigned to each inpatient and outpatient at the University of Chicago Medical Center with an MRSA infection in 2004 to 2005. Antimicrobial susceptibilities and molecular characteristics of MRSA isolates were assessed. Patients were stratified by lesion characteristics.
Of MRSA isolates from 262 patients with purulent skin and soft tissue infections (SSTIs), 231 (88%) were susceptible to clindamycin, 253 (97%) contained staphylococcal chromosomal cassette mec (SCCmec) IV, and 245 (94%) contained Panton-Valentine leukocidin (pvl) genes, characteristics associated with community-associated MRSA strains. The presence of a purulent SSTI had a positive predictive value of 88% for a clindamycin-susceptible MRSA isolate. Among 87 isolates from a nonpurulent SSTI, 44% were susceptible to clindamycin and 34% contained pvl genes. In 179 invasive MRSA disease isolates, 33% were clindamycin-susceptible and 26% carried pvl genes.
A purulent MRSA SSTI strongly predicted the presence of a clindamycin-susceptible MRSA isolate. Presence of the pvl genes was almost universal among MRSA isolates causing purulent SSTIs; this was less common in nonpurulent SSTIs and other clinical syndromes.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Emergence of Panton-Valentine leukocidin (PVL)-positive methicillin-resistant Staphylococcus aureus (MRSA) is a public health concern worldwide. PVL is associated with community-associated MRSA and is linked to skin and soft tissue infections (SSTIs). However, PVL genes have been detected among healthcare-associated (HA) MRSA isolates. The diseases associated with PVL-positive HA-MRSA isolates and distributions of PVL-encoding bacteriophages among HA-MRSA have not been determined. A total of 259 HA-MRSA strains isolated between 2009 and 2012 in China, from inpatients with SSTIs, pneumonia, and bacteremia were selected for molecular typing, including staphylococcal cassette chromosome mec typing, multilocus sequence typing, and staphylococcal protein A gene typing. The PVL genes and PVL bacteriophages in MRSA isolates were characterized by polymerase chain reaction. Among the tested MRSA isolates, 28.6% (74/259) were PVL-positive. The high prevalence of PVL-carrying HA-MRSA was observed to be associated with SSTIs, but not with pneumonia and bacteremia. PVL-positive HA-MRSA isolates were colonized mainly by infective PVL phages, namely, Φ7247PVL, ΦSLT, and ΦSa2958. The distribution of PVL-carrying bacteriophages differed geographically. Our study highlights the potential risk of the emergence of multidrug-resistant HA-MRSA strains with increased virulence.
    Journal of Clinical Microbiology 10/2014; 53(1). DOI:10.1128/JCM.01722-14 · 4.23 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Panton-Valentine leukocidin (PVL; gene designation lukF/S-PV) is likely an important virulence factor for Staphylococcus aureus (S. aureus), as qualitative expression of the protein correlates with severity for specific clinical presentations, including skin and soft tissue infections (SSTIs). Development of genetic approaches for risk-assessment of patients with S. aureus infections may prove clinically useful, and whether lukF/S-PV gene expression correlates with specific clinical presentations for S. aureus has been largely unexplored. In the present study, we quantified lukS-PV mRNA among 96 S. aureus isolates to determine whether expression levels correlated with specific clinical presentations in adults and children. Expression level of lukS-PV mRNA among isolates from skin and soft tissue infections (SSTIs) was significantly greater than among isolates from blood stream infection (BSIs), and expression level of lukS-PV mRNA among BSI isolates from children was significantly greater than for BSI isolates among adults. Moreover, expression level of lukS-PV mRNA among community-acquired (CA) isolates was significantly greater than for hospital-acquired (HA) isolates. These data justify additional studies to determine the potential clinical utility for lukS-PV mRNA quantification as a predictive tool for severity of S. aureus infection.
    PLoS ONE 12/2013; 8(12):e83368. DOI:10.1371/journal.pone.0083368 · 3.53 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Background. Community-associated methicillin-resistant S. aureus (CA-MRSA) is now the most common organism isolated from purulent skin infections. Antibiotics are usually not beneficial for skin abscess, and national guidelines do not recommend CA-MRSA coverage for cellulitis, except purulent cellulitis, which is uncommon. Despite this, antibiotics targeting CA-MRSA are prescribed commonly and increasingly for skin infections, perhaps due in part to lack of experimental evidence among cellulitis patients. We test the hypothesis that antibiotics targeting CA-MRSA are beneficial in the treatment of cellulitis. Methods. Randomized, multicenter, double-blind placebo-controlled trial, enrolling patients during 2007-2011, with cellulitis, no abscess, symptoms <1 week, and no diabetes, immunosuppression, peripheral vascular disease, or hospitalization ( NCT00676130). All participants received cephalexin. Additionally, each was randomized to trimethoprim-sulfamethoxazole or placebo. We provided 14 days of antibiotics, and instructed participants to continue therapy for ≥1 week, then stop 3 days after they felt the infection to be cured. Our main outcome measure was the risk difference for treatment success, determined in person at 2 weeks, with telephone and medical record confirmation at 1 month. Results. We enrolled 153, and 146 had outcome data for intent-to-treat analysis. Median age was 29, range 3-74. Of intervention participants, 62/73 (85%) were cured, vs. 60/73 controls (82%), a risk difference of 2.7% (95%CI -9.3% to 15%, p=0.66). No covariates predicted treatment response, including nasal MRSA colonization and purulence at enrollment. Conclusions. Among patients diagnosed with cellulitis without abscess, the addition of trimethoprim-sulfamethoxazole to cephalexin did not improve outcomes, overall or by subgroup.
    Clinical Infectious Diseases 03/2013; 56(12). DOI:10.1093/cid/cit122 · 9.42 Impact Factor


1 Download
Available from