Antibiotic resistance and plasmid profiles of Escherichia coli and Klebsiella isolated from in-patients receiving prolonged antibiotic therapy.

Distribution by serogroup, phage type, colicin production, colicin type, sensitivity to antibiotics and plasmid characteristics of 74 Escherichia coli and 11 Klebsiella strains isolated from hospitalized patients receiving prolonged antibiotic therapy indicated that the infections were not associated with the hospital environment. Resistance was tested to 26 antibiotics, some of them being not generally used in therapy; 30 strains were resistant to 4 to 17 antibiotics. There was a significant difference in the antibiotic resistance of strains derived from patients with urinary-tract infections (UTI) and with leukaemia (LP). As compared to the UTI group, among E. coli strains in the LP group the frequency of multiple resistance was significantly higher, the MIC values were higher and R-plasmids were more frequent. Out of 30 multiple resistant E. coli strains 27 were R-plasmid carriers. Three different kinds of plasmid profile were shown in more than one strain (2 out of 10 UTI strains and 3 and 2 out of 10 LP strains). The rest of the isolates differed in plasmid profile from these and from one another; the presence of "epidemic plasmid" was not demonstrated. Plasmid epidemiological examinations may forecast the efficacy of an antibiotic or of a group of antibiotics.