Characterization of multiply resistant Proteus mirabilis isolates in Hungary.

According to a survey on tendencies of antibiotic resistance in Hungary (1974-1983), the emergence of multiresistant (MR) Proteus mirabilis isolates is a new phenomenon. A total of 60 strains resistant to 11-16 antibiotics were collected from various specimens and geographical locations. Except for cefoperazone, third generation cephalosporins, amikacin, netilmicin and ofloxacin were effective in vitro against multiply resistant P. mirabilis isolates. Out of them 62% belonged to O18, a serogroup not shown in early studies in Hungary; moreover, in serogroup-distribution the present collection differed sharply from isolates examined in 1956. All but two strains produced the same aminoglycoside-modifying enzyme ANT (2"), and all of them proved beta-lactamase positive in nitrocephin test. All multiresistant strains harboured 2-4 plasmids, whereas the sensitive isolates had no plasmids. The presence of two plasmids (62 and 22 Mdal) occurring in 85% of the isolates was a characteristic feature of the multiresistant P. mirabilis isolates. In contrast to these plasmids some other ones (17.5, 103 and 113 Mdal) could be transferred to Escherichia coli recipient. There was no relationship between plasmid profiles, serogroups and resistance patterns.