[Salmonella montevideo from a hospital outbreak with different antibiograms determined by a plasmid].

From May to June 1984 an outbreak of Salmonella montevideo occurred in the neonatal ward of a district's hospital. 26 babies were involved and mild forms of disease were observed in the most cases. The infants were hospitalized from different reasons and treated chemotherapeutically prior to the nosocomial infection. The Salmonella montevideo strains isolated from the faeces of the infants showed five different antibiograms. In all strains the multiple drug resistance was determined by a single plasmid belonging to the incompatibility group C and with a molecular weight of 110 Md or 100 Md in the threefold resistant strains. These plasmids were found also in the faecal flora (E. coli and Klebsiella) of all patients. It is suggested that a transfer of the plasmids from E. coli or Klebsiella to Salmonella montevideo occurred under in vivo condition, since distinct patients excreted susceptible as well as resistant Salmonellae. This example shows the necessity to include antibiogram and plasmid analysis as epidemiological markers.