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Dina F. Khamash et al
Changing antibiotic resistance patterns for Staphylococcus aureus surgical site infections
Dina F. Khamash MD1, Aaron M. Milstone MD, MPH1, Karen C. Carroll MD2, Avinash Gadala MS, BPharm3,
Eili Klein PhD4,5, Lisa L. Maragakis MD, MPH6, Sara E. Cosgrove MD, MS6 and Valeria Fabre MD6 1Division of Infectious Diseases, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland, 2Division of Medical Microbiology, Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland, 3Hospital Epidemiology and Infection Control, The Johns Hopkins Hospital, Baltimore, Maryland, 4Department of Emergency Medicine, The Johns Hopkins Hospital, Baltimore, Maryland, 5Center for Disease Dynamics, Economics and Policy, Washington, DC and 6Division of Infectious Diseases, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
Beta-lactam antibiotics such as cefazolin are first-line agents for preoperative prophylaxis, whereas clindamycin is often administered to patients with a reported penicillin allergy.1 Recent studies have reported increased resistance to clindamycin in Staphylococcus aureus (SA) isolates fromboth pediatric and adult populations, and these changes may have implications for surgical site infection (SSI) prophylaxis and empirical management.2,3 Antibiotic resistance trends of SA isolates recovered from SSIs in adults in the United States have not been recently described.
Methods
We conducted a retrospective observational study of SA isolates recovered from SSIs in patients ≥18 years of age at the Johns Hopkins Hospital between January 1, 2012, and December 1, 2017, for the following procedures: craniotomy, coronary artery bypass grafting (CABG), hysterectomy, cesarean section, colorectal surgery, spinal fusion, laminectomy, and hip and knee arthroplasty (HKA). A list of cultures that grew SA was obtained from Johns Hopkins Pathology Data Services and was cross-referenced with the SSI database maintained by the Department of Hospital Epidemiology and Infection Control. Charts were reviewed to assess for documented penicillin allergy and antibiotic surgical prophylaxis. Due to changes in electronic medical records, antibi- otic prophylaxis data were available only for 2015–2017 cases. Trends in the proportion of resistant isolates over time were ana- lyzed using the Cochran-Armitage test for trend. The association between the proportions of resistant isolates and choice of SSI pro- phylaxis was analyzed using the Fisher exact test. P < .05 was con- sidered statistically significant for all tests. Data were analyzed using Stata version 13 software (StataCorp, College Station, TX). The Johns Hopkins University Institutional Review Board approved this study.
Results
In total, 109 cultures from unique patients were included in the study. Clindamycin resistance increased from 20% in 2012 to 38% in 2017 (P < .01), while resistance to tetracycline decreased significantly from 20% to 0% during the same period (P < .01) (Fig. 1). Trimethoprim-sulfamethoxazole (TMP-SMX) resistance remained relatively unchanged from 10% in 2012 to 13% in 2017 (P = .63). Erythromycin resistance decreased from 40% in 2012 to
Author for correspondence: Valeria Fabre, Email:
mfabre1@jhmi.edu Cite this article: Khamash DF, et al. (2019). Changing antibiotic resistance patterns for
Staphylococcus aureus surgical site infections. Infection Control & Hospital Epidemiology, 40: 486–487,
https://doi.org/10.1017/ice.2019.4
© 2019 by The Society for Healthcare Epidemiology of America. All rights reserved.
29% in 2017 (P = .18). Between 2012 and 2017, there was a 9% decrease in methicillin-resistant S. aureus (MRSA) SSIs (P = .84). The distribution of SA SSI by surgery type was as follows: spinal fusion and laminectomy (27%), craniotomy (23%), CABG (17%), cesarean section (12%), colorectal (11%), hysterectomy (8%), and hip and knee arthroplasty (HKA, 2%). Overall, of 68 caseswithavailable SSI prophylaxis and allergy data,
13 patients (20%) had a reported penicillin allergy. Also, 5 of these patients received clindamycin even though a high severity reaction was recorded in only 1 patient. Of the 5 patients who received clindamycin, 2 developed a clindamycin-resistant SA SSI.
Discussion
Our results show a significant increase in clindamycin resistance among SA isolated from SSIs over the last 6 years at our institution. This finding is in agreement with previous reports of non-SSI SA isolates in children and adults observed in different areas in the United States in recent years.2,3 Unlike previous reports, SA SSIs at our hospital demonstrated a significant decline in tetracycline resistance. Susceptibility to TMP/SMX remained high throughout the study period, whereas resistance to methicillin declined over the last 3 years. As reported by others,4 most patients in our cohort had incom-
plete allergy histories. Clindamycin is used with high frequency as an alternative to β–lactams in patients with penicillin allergy labels (whether the allergy is true or not).1 Efforts to optimize anti- biotic selection in the operating room may include education on accurate determination and documentation of penicillin allergy histories and decision-support tools to ensure that patients receive β-lactams whenever possible. Also, unnecessary deviations from recommended β-lactam–containing regimens should be reduced as much as possible. Increasing clindamycin resistance in SSIs SA raises concerns
about its use as an alternative surgical prophylaxis agent. Routine use of vancomycin is not recommended given potential risks of emergence of vancomycin-nonsusceptible Staphylococcus isolates, its prolonged infusion time, associated toxicity, and evi- dence that it is inferior to β-lactamagents for surgical prophylaxis.5 Therefore, infection control and antimicrobial stewardship programs need to discuss alternatives to clindamycin based on each institution’s antibiogram and feasibility. At our institution, we recommend vancomycin for patients with severe PCN allergy undergoing clean procedures with implants or cardiac surgery. We did not specifically collect data on clindamycin use; how- ever, at our hospital, clindamycin is reserved for patients with
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