OUTBREAK OF EXTENDED-SPECTRUM BETA-LACTAMASE KLEBSIELLA-PNEUMONIAE IN A MEDIUM AND LONG-STAY HOSPITAL

Fourteen extended-spectrum beta-lactamase (ES beta la) Klebsiella pneumoniae strains were isolated from 14 inpatients between February 1993 and February 1994, in a medium- and long-stay neurological unit. For this reason an epidemiological study was begun, based on strain typing and examination of patient files. Strain typing was carried out by two methods (i) the analysis of antibiotic resistance, showing 7 different antibiotypes among the 14 strains studied, (ii) the analysis of esterase and dehydrogenase electrophoretic polymorphism in polyacrylamide-agarose gel. The method was checked by analysing 11 Klebsiella pneumoniae strains with wild phenotype for beta-lactam antibiotics, which were isolated during the same period in the same unit. Simultaneously 6 other strains isolated during the same period in some other units of the hospital were analysed. Nine electrophoretic types were found among the 31 strains (wild and ES beta las). The analysis of the results showed that 8 isolates of the group of 14 ES beta las had the same antibio-type and electrophoretic type. This demonstrates that one epidemic strain was responsible for two outbreaks, the first one in April and the second one in August-September. A case control investigation was carried out to define the risk factors of infection. Files were examined for the 14 infected inpatients and for 20 control inpatients from the same unit during the same period. Statistical analysis was performed with Epi Info software 5 (CDC Atlanta). Length of stay, dependence and malnutrition levels,;and urinary sphincter disfunction were the most significant risk factors.