Antimicrobial resistance, beta-lactamase production, drug-resistance genes, conjugative R-plasmids, and plasmid profiles of enterotoxigenic Escherichia coli isolated from diarrheic piglets in Okinawa prefecture [Japan]
2001
Matayoshi, M. (Okinawa-ken. Inst. of Animal Health, Naha (Japan)) | Nakazawa, M.
Seventy-nine strains of enterotoxigenic Escherichia coli (ETEC) isolated from diarrheic piglets (aged 1 to 43 days) between 1989 and 1998 in Okinawa Prefecture were investigated for their antimicrobial resistance, beta-lactamase production, drug-resistance genes (TEM, SHV, Toho-1, MEN-1, gyrA), R-plasmid properties, and plasmid profiles. Percentages of strains resistant to the following drugs were streptomycin (93.7%), oxytetracycline (87.3%), chloramphenicol (75.9%), kanamycin (38.0%), sulfamethoxazole-trimethoprim (29.1%),ampicillin (25.3%), and gentamicin (2.5%). All strains were susceptible to colisitin (CL), oxolinic acid (OXA), and ceftiofur (CTF). The isolates demonstrated 16 drug-resistance patterns. Multiple resistance was demonstrated by 73 isolates (92.4%), of which all were resistant to at least 2 antimicrobial substances. Only 1 strain was susceptible to all the antimicrobial agents tested. beta-lactamases (penicillinases) were detected by means of the acidometric method in all strains resistant to ampicillin. TEM genes were detected in 21 (26.6%) strains, and gyrA genes in 20 (25.3%) strains. Conjugated R-plasmids were found in 41 (51.9%) strains. An especially highfrequency of resistance transfer was observed in multidrug-resistant strains. Several sizes (1 - 8) of plasmid DNA bands occurred in all strains. Plasmids from the same source displayed identical or similar profiles, whereas those from different sources showed distinct profiles.
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