Decreased Vancomycin Susceptibility of Coagulase-Negative Staphylococci in a Neonatal Intensive Care Unit: Evidence of Spread of Staphylococcus warneri

Abstract

Coagulase-negative staphylococci (CoNS) are important pathogens in premature neonates; decreasing glycopeptide susceptibility has been observed among these isolates. The epidemiology of colonization with CoNS, the organisms' vancomycin susceptibilities, and genetic relatedness were studied over 6 months in a tertiary-care neonatal unit. A total of 321 isolates of CoNS were isolated. Seventy-five percent of the infants were colonized at admission, and virtually all were colonized thereafter. Common species were Staphylococcus epidermidis (69%), S. warneri (12%), S. haemolyticus (9.7%), and S. hominis (5.6%). A total of 3.9% of CoNS isolates had decreased vancomycin susceptibility (DVS) (MICs > 2.0 g/ml); isolate recovery was associated with a stay in a neonatal intensive care unit for >28 days (P ‫؍‬ 0.039), vancomycin exposure (P ‫؍‬ 0.021), and S. warneri colonization (P < 0.0001). Nine of 12 (75%) CoNS with DVS were S. warneri, had enhanceable high-level resistance in vitro, were indistinguishable or closely related by pulsed-field gel electrophoresis, and were different from 29 vancomycin-susceptible S. warneri isolates. Epidemiological analysis suggested unsuspected nosocomial spread. Species determination in certain settings may aid in the understanding of emerging nosocomial problems.

Species Distribution and Antibiotic Resistance in Coagulase-negative Staphylococci Colonizing the Gastrointestinal Tract of Children in Ile-Ife, Nigeria

“…Evidence indicates increasing tendency towards decreasing susceptibility to vancomycin and other glycopeptides in CoNS species worldwide [15] and the result of this study is in agreement with these observations.…”

Clonality, virulence and the occurrence of genes encoding antibiotic resistance among Staphylococcus warneri isolates from bloodstream infections

“…Previously, Center et al (2003) reported the presence of an endemic clone of S. warneri with enhanceable resistance to vancomycin in a neonatal intensive care unit in a hospital in Philadelphia. …”

Colonization pattern of coagulase-negative staphylococci in preterm neonates and the relation to bacteremia

“…Since persistence of single CoNS clones for several years is well documented in neonatal intensive care units (NICUs) (7)(8)(9)(10), as is the emergence of multi drug resistant CoNS strains (including glycopeptides) (7,8), there is an urgent need for epidemiologic surveillance in the NICUs and preventive/infection control strategies against neonatal invasive CoNS infections (11,8).…”