A high prevalence of methicillin-resistant Staphylococcus aureus among surgically drained soft-tissue infections in pediatric patients
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- Seal, J., Glynn, L., Statter, M. et al. Pediatr Surg Int (2006) 22: 683. doi:10.1007/s00383-006-1684-x
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Over the past decade, methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a global problem, prompting extensive surveillance efforts. A previous study of S. aureus isolates at our institution revealed alarming increases in the prevalence of MRSA with no sign of plateau. However, evidence of MRSA in pediatric surgical patients remains largely anecdotal, as there are no published reports of institutional MRSA surveillance in the pediatric surgical literature. We conducted a retrospective review of incision and drainage (I and D) procedures at our institution from 1998 through 2004. All I and D procedures performed at the University of Chicago Children’s Hospital were identified and the patients’ charts reviewed for pertinent information. A total of 99 I and D procedures were performed during the study period, ranging from 5 in 1998 to 32 in 2004. Among cultures with positive growth, 52 (65.8%) were MRSA, 14 (17.7%) were methicillin-sensitive S. aureus, and 13 (16.5%) were miscellaneous species. The number of MRSA isolates increases from 2 in 1998 to 20 in 2004, the largest increase occurring during the last 3 years of the study. A large proportion of MRSA isolates were resistant to antimicrobials from other classes, with over 70% being resistant to both erythromycin and cefazolin. A majority of MRSA isolates (71.4%) were obtained from patients with no record of prior hospitalization. Our analysis confirms a high prevalence of MRSA among soft-tissue infections requiring surgical drainage. In addition, a majority of MRSA isolates were resistant to multiple antimicrobials and were isolated from children without a previous documented exposure to the hospital milieu. Thus, pediatric surgeons should be aware of MRSA prevalence and resistance patterns in the local communities.
KeywordsMRSAAbscessAntimicrobial resistanceStaphylococcus aureus
Staphylococcus aureus is a ubiquitous pathogen responsible for sporadic infections and epidemics worldwide. Over the past decade, methicillin-resistant S. aureus (MRSA) has emerged as a global problem, prompting extensive surveillance efforts [1–6]. Within our community, MRSA has emerged as a serious clinical problem. A previous study of S. aureus isolates at our institution revealed an alarming increase in the prevalence of MRSA with no sign of plateau .
In addition to an increase in prevalence, important changes in the epidemiology of MRSA have recently been reported. Although once considered to be primarily a nosocomial pathogen prevalent only among patients with significant hospital exposure, studies at our institution  and others  have reported a high proportion of MRSA infections in patients without prior hospital exposure. Thus, MRSA has become clinically important in the management of community-associated as well as nosocomial infections.
Methicillin-resistance in S. aureus is associated with resistance to all β-lactam antimicrobials including penicillins and cephalosporins. In addition, MRSA isolates are often multiply resistant to antimicrobial agents of other classes [10, 11], including macrolides and fluoroquinolones, further limiting the arsenal of therapies. In fact, resistance to last-resort therapies such as vancomycin [12, 13] and linezolid  has already been reported, underscoring the urgency of efforts to characterize and contain this pathogen.
Despite a wealth of anecdotal evidence, the epidemiology of MRSA among pediatric surgical patients remains poorly characterized with no published reports of MRSA surveillance in the pediatric surgical literature. Therefore, we conducted a retrospective review of incision and drainage (I and D) procedures for soft-tissue abscesses at our institution from January 1998 through December 2004.
Materials and methods
We conducted a retrospective review of electronic medical records of 99 patients operated on at the University of Chicago Children’s Hospital for I and D of soft-tissue abscesses from January 1998 through December 2004. The study was approved by the University of Chicago Institutional Review Board. The University of Chicago’s Children’s Hospital is an urban, tertiary care medical center located in Chicago, IL, USA. The infection control policy for MRSA infections at our institution did not change during the study period. Patients with S. aureus isolates demonstrating resistance to methicillin were placed in isolation with contact precautions. Information regarding referral patterns during the study period was not available.
Statistical analyses were performed using Prism v4.01 (Graphpad Software, San Diego, CA, USA). Mean age and length of stay analysis was made using one-way ANOVA. Trends in number of isolates by year were analyzed with linear correlation. Contingency tables and chi-square analyses were used for analysis of prior hospitalization.
Characteristics of patients and isolates
Isolate breakdown by year, organism, and site of abscess
Mean patient age (months)
Mean LOS (days)
Site of abscess
Prevalence of MRSA among isolates
MRSA is not associated with prior hospitalization
MRSA is prevalent among all age groups
MRSA isolates are often cross-resistant to other antimicrobial agents
Methicillin-resistant Staphylococcus aureus has been a growing concern for surgeons for decades. Recent increases in its prevalence in some areas and changes in its epidemiology have mandated a renewed awareness of this pathogen. Although anecdotal evidence of its importance abounds, the role of MRSA specifically among pediatric surgical patients has remained poorly characterized in the literature. In this study we confirm that MRSA is prevalent among soft-tissue abscesses in pediatric patients at our institution and that the characteristics of MRSA isolates in our study are concordant with reported changes in its epidemiology.
We report an increasing prevalence of MRSA isolates among cultures from I and D procedures in pediatric patients, with the greatest increase occurring from 2000 to 2004. Importantly, most MRSA isolates were obtained from patients without a documented prior hospitalization. Although documentation of prior hospitalization is only a rough estimate of hospital exposure, the fact that such a large proportion of MRSA isolates were obtained from patients without prior hospitalization supports recent trends of this organism extending to the community setting.
Methicillin-resistant Staphylococcus aureus isolates demonstrated a high rate of co-resistance to non-β-lactam antimicrobials with over 80% expressing resistance to both macrolides and cephalosporins. Antimicrobials traditionally used for empiric management of soft-tissue infections, such as β-lactams and cephalosporins, may no longer provide sufficient coverage for empiric treatment of infections in communities where MRSA is prevalent. While some clinical scenarios may accommodate waiting for the results of culture and sensitivity testing, empiric management often necessitates initiating treatment before culture results and sensitivities are available. In such cases, alternative antimicrobials may be more appropriate to provide coverage for MRSA.
At our institution, clindamycin is frequently used for empiric treatment of soft-tissue infections when MRSA is suspected. Although we report three MRSA isolates resistant to clindamycin during the study period, alternative antimicrobials with superior coverage against MRSA, such as linezolid and vancomycin, should be reserved, as they represent a last line of defense against MRSA infections. Selecting an appropriate alternative agent will depend on the local epidemiology of MRSA in the community. Thus, it is important to know the local epidemiology of MRSA to make informed management decisions. Judicious use of antimicrobials and stringent infection control policies are imperative to control this organism, as few last-resort therapies are available .
The modest size and retrospective design of this study limit the extent to which our results can be generalized. Furthermore, we were unable to ascertain any changes in the referral pattern to our institution during the study period. Thus, it is unknown whether the increase in MRSA prevalence we observed was due to a widespread increase, or only a few isolated communities. Further studies of the epidemiology of MRSA isolates in our area are merited to address this concern. Antimicrobial resistance in S. aureus is a worldwide problem and varies greatly between regions. Until a larger, prospective study of MRSA isolates in pediatric surgical patients is available, the observations from our small, sentinel study will hopefully raise awareness of MRSA among pediatric surgeons in all settings.