A total of 57 Vibrio vulnificus isolates from coastal water were characterized for their antimicrobial resistance, plasmid profiles and were typed by the PCR-based techniques: a random amplification of polymorphic DNA (RAPD) method and the enterobacterial repetitive intergenic consensus sequence (ERIC) method. All isolates were susceptible to chloramphenicol, nalidixic acid, tetracycline and trimethoprim-sulfamethoxazole. Fifty-one isolates were resistant to one or more of the other antibiotics tested. Plasmid analysis indicated that only 18 isolates carried small plasmids of 1.6 to 16 megadaltons. Analysis of the RAPD and ERIC DNA fingerprints of the V. vulnificus isolates with Gel Compare and cluster analysis software revealed significant genetic heterogeneity among these isolates. The combination of RAPD and ERIC analysis allowed us to distinguish all isolates. Thus, the combination of the two techniques is recommended for epidemiological investigation.
Ten strains of Salmonella weltevreden isolated from poultry sources were examined and found to contain plasmid DNA ranging in size from 1.8 to 68.5 MD. All isolates were susceptible to carbenicillin, cephalothin, ceftriazone, gentamicin, kanamycin and nalidixic acid, but resistance to bacitracin (100%), penicillin G (100%), rifampicin (100%), sulphamethoxazole (100%), cefuroxime (80%) and tetracycline (60%) was recorded. The 55 MD plasmid of strain SW5 determined resistance to penicillin G and tetracycline, which was transmissible to the E. coli K12 recipient at a frequency of 3.52 x 10(-5) transconjugants per input donor cell. The results of arbitrarily primed polymerase chain reaction (AP-PCR), using two 10-mer oligonucleotides and PCR-ribotyping to differentiate between the ten strains of S. weltevreden were compared. The strains were separated into ten different genome types by AP-PCR but were indistinguishable by PCR-ribotyping. These results suggest that poultry may constitute a reservoir for disseminating antibiotic resistance and that AP-PCR may be a valuable tool for epidemiological studies.