Epidemiological profile of methicillin resistant Staphylococcus epidermidis with diminished sensitivity to teicoplanin and isolated from neutropenic patients at the National Center of Bone Marrow Transplantation in Tunis]

Fifty-seven methicillin resistant S. epidermidis with decreased susceptibility to teicoplanin were obtained from 14 neutropenic patients on a period of 11 months (19 February-31 December 1998) from essentially blood culture (30 strains) and ORL specimens (21 strains). The MIC90 of methicillin, gentamicin, ofloxacin and telcoplanin were respectively 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 (> two strains). For epidemiological control, a MetiR and TeicoR S. epidermidis isolated from blood culture taken from Caen CHU was include in study. Twenty-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 can be subdivised on three sub-types (differed by a single to three bands): seven strains have the pulsotype Ia and obtained respectively from five strains 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 recently, infections due to coagulase negative staphylococci have been regarded as endogenous in origin, these results with some pulsotype of S. epidermidis MetiR and TeicoR in the two separate units suggered a nosocomial origin, probably by medical staff transmission because no S. epidermidis TeicoR was isolated from environmental control during all the period.