[Serratia marcescens infections in a hospital: typing of isolated strains].

Abstract

Ninety six strains of Serratia marcescens were isolated from one hospital. Strains originated from various sources: pressure transducer head (14), arterial catheter tip (4), blood (33), sputum (12), bronchial aspirate (10), urine (10), wound (8), miscellaneous (5). Most of the blood strains were isolated on the intensive care unit (ICU). Contaminated pressure transducer heads seemed to be involved in a nosocomial epidemic. All strains were characterized by serotyping, antibiotic resistance pattern, plasmid profile typing and biotyping. It was demonstrated that the epidemic strain was of serotype O14H4, biotype A5, carrying one plasmid coding for the resistance against gentamicin, streptomycin and sulfamethoxazole. The epidemic type was encountered with the majority of blood isolates (26/33) and with all the transducer head isolates from the ICU (11/11). Isolates from catheter tips (2/4), bronchial aspirate (3/10) and urine (1/10) belonged also to the epidemic type. Within the non-epidemic strains, the most prevalent serotypes were O14H12 (39%) and O14H4 (36%), corresponding well with the distribution of serotypes from a national survey study: O14H12 (36%), O14H4 (24%). Two biotypes were predominant within the non-epidemic strains: A5 (46%) and A8b (32%). Plasmid carriage was observed with 46% of the non-epidemic strains. A plasmid, similar to the epidemic plasmid, was detected in 7 strains, differentiating from the epidemic strain by the serotype and/or the biotype.