Decreased vancomycin susceptibility of coagulase-negative staphylococci in a neonatal intensive care unit: evidence of spread of Staphylococcus warneri.
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 microg/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.
Center
Kimberly J
KJ
St. Christopher's Hospital for Children, Drexel University College of Medicine, Philadelphia, Pennsylvania 19134, USA. kjcn0124@aol.com
Reboli
Annette C
AC
Hubler
Robin
R
Rodgers
Gail L
GL
Long
Sarah S
SS
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003030:Coagulase / Q000378:metabolism*; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007363:Intensive Care Units, Neonatal; D008297:Male; D008826:Microbial Sensitivity Tests; D013203:Staphylococcal Infections / Q000382:microbiology; D013210:Staphylococcus / Q000187:drug effects* / Q000201:enzymology; D014640:Vancomycin / Q000494:pharmacology*; D020713:Vancomycin Resistance
D000900:Anti-Bacterial Agents; D003030:Coagulase; D014640:Vancomycin