An epidemiological study of Methicillin resistant S-epidermidis with decreased susceptibility to teicoplanin isolated from neutropenic patients in National Center of Bone marrow Transplantation in Tunis

Fifty-seven methicillin resistant S. epidermidis with decreased susceptibil ity to teicoplanin were obtained from 14 neutropenic patients on a period o f 11 months (19 February-31 December 1998) from essentially blood culture ( 30 strains) and ORL specimens (21 strains). The MIC90 of methicillin, genta micin, ofloxacin and teicoplanin were respectivly 1024, 1024, 512 and 32 mg /l. We applied pulsed field gel electrophoresis (PFGE) after Smal digestion to 21 isolates choosed between eight patients with multiple isolates (> tw o strains). For epidemiological control, a MetiR and TeldoR S. epidermidis isolated from blood culture taken from Caen CHU was include in study. Twent y-one isolates were separated by PFGE into eight group, from I to VIII. The control strain was classed in group IX Group I include 14 strains which ca n be subdivised on three sub-types (differed by a single to three bands): s even strains have the pulsotype la and obtained respectivly from five strai ns in transplantation unit and two strains in hematology unit. Two strains have the pulsotype Ib and isolated in the two units. Five strains have the pulsotype Ic and obtained also from transplantation unit (four strains) and hematology unit (one strain). All the other pulsotypes were identified in only one strain, frequently in association with the pulsotype I. Until rece ntly, infections due to coagulase negative staphylococci have been regarded as endogenous in origin, these results with some pulsotype of S. epidermid is MetiR and TeicoR in the two separate units suggered a nosocomial origin, probably by medical staff transmission because no S. epidermidis TeicoR wa s isolated from environnemental control during all the period, (C) 2001 Edi tions scientifiques et medicales Elsevier SAS.