Molecular analysis of clinical isolates of Providencia alcalifaciens

In an attempt to elucidate the virulence factors and the pathogenic mechani sms of Providencia alcalifaciens, 36 isolates identified in 1994-1995 in Re cife city, Brazil were analysed by PCR to investigate the presence of DNA s equences homologous to virulence genes described in other invasive enteroba cteria, as well as their ability to invade HeLa cells, their plasmid profil es and antibiotic resistance patterns. The genetic diversity of the isolate s was also analysed by RAPD-PCR. pile homologous sequences of virulence gen es were observed with any of the P. alcalifaciens isolates studied. Ten iso lates had no plasmid and 26 harboured one-to-Eve plasmids of 147-<6.9 kb. I nvasion of HeLa cells was observed in only 10 isolates. No correlation betw een the plasmid content of the strains, their invasion of HeLa cells or the ir resistance to antimicrobial drugs could be established. The isolates cou ld be distributed into 10 genotypic groups by RAPD-PCR. Considering the gen otypic profile and ability to invade HeLa cells, 7 of the 10 invasive isola tes belonged to the same genotypic group. The presence of invasive isolates in the same or a related genotypic group suggests the existence of a clona l lineage responsible for the invasiveness.