Infection Control & Hospital Epidemiology (2019), 40, 333–340 doi:10.1017/ice.2019.3
Original Article
The prevalence of antiseptic tolerance genes among staphylococci and enterococci in a pediatric population
Lauren M. Sommer MS1, Jennifer L. Krauss PhD2, Kristina G. Hultén PhD1, James J. Dunn PhD2, Sheldon L. Kaplan MD1 and J. Chase McNeil MD1 1Department of Pediatrics, Section of Infectious Diseases, Baylor College of Medicine and Texas Children’s Hospital, Houston, Texas and 2Department of Pathology, Baylor College of Medicine and Texas Children’s Hospital, Houston, Texas
Abstract
Objective: The smr and qacA/B genes in Staphylococcus aureus confer tolerance to antiseptics and are associated with nosocomial acquisition of infection and underlying medical conditions. Such antiseptic tolerance (AT) genes have also been reported in coagulase-negative staphy- lococci (CoNS) and enterococci, however, few data are available regarding their prevalence. We sought to describe the frequency of AT genes among bloodstream isolates of S. aureus, CoNS and enterococci at Texas Children’s Hospital (TCH).
Methods: Banked CoNS, S. aureus and enterococci isolated from blood cultures collected bewteen October 1, 2016, and October 1, 2017, were obtained from the TCH clinical microbiology laboratory. All isolates underwent polymerase chain reaction (PCR) assay for the qacA/B and smr genes. Medical records were reviewed for all cases.
Results: In total, 103 CoNS, 19 Enterococcus spp, and 119 S. aureus isolates were included in the study, and 80.6% of theCoNSpossessed at least 1 ATgene compared to 37% of S. aureus and 43.8% of E. faecalis isolates (P<.001). Among CoNS bloodstream isolates, the presence of either AT gene was strongly associated with nosocomial infection (P < .001). The AT genes in S. aureus were associated with nosocomial infection (P = .025) as well as the diagnosis of central-line–associated bloodstream infection (CLABSI; P = .04) and recent hospitalizations (P < .001). We found no correlation with genotypic AT in E. faecalis and any clinical variable we examined.
Conclusions: Antiseptic tolerance iscommon among bloodstream staphylococci and E. faecalis isolates at TCH. AmongCoNS, the presence of AT genes is strongly correlated with nosocomial acquisition of infection, consistent with previous studies in S. aureus. These data suggest that the healthcare environment contributes to AT among staphylococci.
(Received 15 September 2018; accepted 21 December 2018)
Gram-positive bacteria are the principal causative agents of healthcare-associated infections (HAIs) in both adults and chil- dren.1–3 Chlorhexidine gluconate (CHG)-based antiseptics are commonly employed in efforts to diminish the frequency of HAIs.4–8 These strategies have been endorsed in guidelines pro- duced by the Centers for Disease Control and Prevention (CDC) and the Infectious Diseases Society of America (IDSA) for the prevention of HAIs.9–11 A number of efflux pump genes in staphylococci are associated
with higher minimum inhibitory concentrations (MICs) and mini- mum bactericidal concentrations (MBCs) to CHG and other antiseptics (eg, benzalkonium chloride and cetrimide).12–15 In S. aureus, the plasmid-borne smr and qacA/B gene complexes have been most commonly implicated, with such organisms often being termed antiseptic tolerant (AT).16 The incidence ofATS. aureus has increased following widespread use of CHG in hospital units, and these organisms are also associated with invasive infections.17–20 In a recent study by our group, the presence of genotypic AT
Author for correspondence: J. Chase McNeil, Email:
Jm140109@bcm.tmc.edu Cite this article: Sommer LM, et al. (2019). The prevalence of antiseptic tolerance genes
among staphylococci and enterococci in a pediatric population. Infection Control & Hospital Epidemiology, 40: 333–340,
https://doi.org/10.1017/ice.2019.3
© 2019 by The Society for Healthcare Epidemiology of America. All rights reserved.
in S. aureus was independently associated with chronic medical comorbidities in the host and nosocomial acquisition of infection.21 The relative prevalence of these genes among S. aureus in pediatric populations varies widely, ranging from 1% to 44.5% depending on geographic location and the type of patients studied.20,22–24 Pediatric-specific data are of relevance given the variable use of CHG in children’s hospitals, particularly in neonatal intensive care units (NICUs), arising from concerns for systemic absorption and safety in young children.25,26 We have reported that among a ran- dom sample of S. aureus isolates at Texas Children’sHospital (TCH), 32.8% possessed either smr or qacA/B,21 suggesting our center represents a high prevalence region for AT. Other important bacterial contributors to HAIs in children
include the coagulase-negative staphylococci (CoNS) and Enterococcus spp.3 CoNS and enterococci can carry smr and qacA/B and their presence has likewise been associated with eleva- tions in antiseptic MICs.27–29 However, the current literature regarding the prevalence and clinical significance of AT in these other important gram-positive pathogens is sparse.30,31 Among a general adult population in Hong Kong, 13.5% ofCoNS colonizing isolates were positive for qacA/B.32 The prevalence of AT genes among pediatric clinical isolates ofCoNS is limited to a report from
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