CLONAL EXPANSION OF STAPHYLOCOCCUS-EPIDERMIDIS STRAINS CAUSING HICKMAN CATHETER-RELATED INFECTIONS IN A HEMATO-ONCOLOGIC DEPARTMENT

lThe detailed analysis of 411 strains of coagulase-negative staphyloco cci (CoNS) obtained from 40 neutropenic hemato-oncologic patients (61 Hickman catheter episodes) on intensive chemotherapy is described. By random amplification of polymorphic DNA (RAPD) analysis, a total of 88 different genotypes were detected: 51 in air samples and 30 in skin c ultures prior to insertion, 12 in blood cultures after insertion, and only 5 involved in catheter-related infections (CRI), Two RAPD genotyp es of Staphylococcus epidermidis predominated, and their prevalence in creased during patient hospitalization. At insertion, these clones con stituted 11 of 86 (13%) CoNS isolated from air samples and 33 of 75 (4 4%) CoNS isolated from skin cultures. After insertion, their combined prevalence increased to 33 of 62 (53%) in catheters not associated wit h CRI and 139 of 188 (74%) in catheters associated with CRT (P = 0.004 1). These two predominant S, epidermidis clones gave rise to a very hi gh incidence of CRI (6.0 per 1,000 catheter days) and a very high cath eter removal rate for CRI, 70%, despite prompt treatment with vancomyc in. A likely source of S. epidermidis strains involved in CRI appeared to be the skin flora in 75% of cases. The validity of these observati ons was confirmed by pulsed-field gel electrophoresis (PFGE) of SmaI D NA macrorestriction fragments of blood culture CoNS isolates. Again, t wo predominant CoNS genotypes were found (combined prevalence, 60%). R APD and PFGE yielded concordant results in 75% of cases. Retrospective ly, the same two predominant CoNS clones were also found among blood c ulture CoNS isolates from the same hematology department in the period 1991 to 1993 (combined prevalence, 42%) but not in the period 1978 to 1982, These observations underscore the pathogenic potential of clona l CoNS types that have successfully and persistently colonized patient s in this hemato-oncology department.