Antimicrobial Susceptibility Trends in Staphylococcus aureus isolated from Pedatric Patients in Military Treatment Facilities
Staphylococcus aureus (SA) is a ubiquitous pathogen which causes a wide range of infections in children. The ongoing epidemic of methicillin-resistant Staphylococcus aureus (MRSA) has led providers to choose alternate therapies such as clindamycin for first-line empiric treatment of both cutaneous and invasive infections. The purpose of this study is to determine annual antimicrobial susceptibility trends among SA isolates from pediatric patients across the Department of Defense (DoD).
Susceptibility data from SA cultures were identified from military treatment facilities across the DoD. Isolates from pediatric patients (<18 years) obtained between 1 January 2005 and 31 December 2013 were included, regardless of culture type or specimen site. The Mantel-Haenszel x2 test for linear trends was performed to evaluate changes in susceptibility to 9 commonly utilized antibiotics over the study period.
41,602 unique isolates from pediatric patients were tested for susceptibility to >1 antimicrobial (Table 1). Changes in oxacillin susceptibility were significant over the study period (p<0.001), with an increase in the percentage of methicillin-sensitive SA (MSSA) isolates from 54.9% to 65.4% over the final 6 years studied (Figure 1). Susceptibility to clindamycin decreased significantly over the study period in the subset of MSSA isolates with no significance in resistance noted in the MRSA isolate subset (Figure 2). Ciprofloxacin susceptibility significantly declined (p<0.001), and among MRSA ciprofloxacin susceptibility declined from 70% to a nadir of 52.4% in 2011, and a subsequent increase to 58.9% in 2013. Susceptibility to all other antibiotics remained stable or increased among MRSA during the study period.
Antimicrobial susceptibility among SA in children has continued to evolve in the post-community acquired-MRSA era. Our data shows a significant decline in methicillin-resistance in SA over the study period and increasing antibiotic resistance in the MSSA isolates. Commonly utilized empiric treatment choices may not be appropriate given these shifts in susceptibility. Continued awareness of susceptibility patterns remains essential in treating pediatric patients with SA infections.
A. M. Maranich, None
D. Sutter, None