PERSISTENCE OF CLONES OF COAGULASE-NEGATIVE STAPHYLOCOCCI AMONG PREMATURE NEONATES IN NEONATAL INTENSIVE-CARE UNITS - 2-CENTER STUDY OF BACTERIAL GENOTYPING AND PATIENT RISK-FACTORS

From 1 January 1995 until 1 January 1996, we studied the molecular epi demiology of blood isolates of coagulase-negative staphylococci (CoNS) in the Neonatal Intensive Care Units (NICUs) of the Sophia Children's Hospital (SCH; Rotterdam, The Netherlands) and the Wilhelmina Childre n's Hospital (WCH; Utrecht, The Netherlands). The main goal of the pre sent study was to detect putatively endemic clones of CoNS persisting in these NICUs, Pulsed-field gel electrophoresis was used to detect th e possible presence of endemic clones of clinical significance. In add ition, clinical data of patients in the SCH were analyzed retrospectiv ely to identify risk factors for the acquisition of positive blood cul tures, In both centers, endemic CoNS clones were persistently present. Thirty-three percent of the bacterial isolates derived from blood cul tures in the SCH belonged to a single genotype, In the WCH, 45% of all bacterial strains belonged to a single clone. These clones were clear ly different from each other, which implies that site specificity is i nvolved. Interestingly, rye observe that the clonal type in the SCH di ffered significantly from the incidentally occurring strains with resp ect to both the average pH and partial CO, pressure of the patient's b lood at the time of bacterial culture. We found that the use of intrav ascular catheters, low gestational age, and a long hospital stay were important risk factors for the development of a putative CoNS infectio n. When the antibiotic susceptibility of the bacterial isolates was as sessed, a clear correlation between the nature of the antibiotics most frequently used as a first line of defense versus the resistance prof ile was observed, We conclude that the intensive use of antibiotics in an NICU setting with highly susceptible patients causes selection of multiresistant clones of CoNS which subsequently become endemic.