Significant increase in antibiotic resistance of Salmonella isolates from human beings and chicken meat in Thailand

Abstract A total of 1715 Salmonella strains, including 600 S. enteritidis , 290 S.derby , 257 S. Weltevreden , 122 S . 1,4,5,12:i:-, 235 S. anatum , and 211 S. typhimurium , originating from 1308 human beings and 407 frozen chicken meat specimens collected in 1993 and 1994 were tested for antibiotic resistance. The disk diffusion method was used with nine disks of chloramphenicol, ceftriaxone, amikacin, kanamycin, ampicillin, sulfamethoxazole plus trimethoprim, nalidixic acid, gentamicin and ofloxacin. The resistance rates of human beings isolates in 1994 to ceftriaxone, amikacin and kanamycin were, respectively, 10.7%, 8.6%, 17.8% in S. enteritidis ; 23.1%, 17.3% 33.0% in S. derby ; 30.9%, 40.2%. 60.4% in S. weltevreden ; 16.1%, 17.7%, 70.9% in S . 1, 4, 5, 12:i:-; 25.7%, 21.6%, 24.7% in S. anatum ; 18.9%, 15.7% 37.8% in S. typhimurium , while those isolates in 1993 to the same three antibiotics were, respectively, 1.8%, 0.6%, 3.7% in S. enteritidis ; 0.8%, 0%, 9.1% in S.derby ; 1.8%, 2.7%, 10.8% in S. weltevreden ; 3.8%, 0%, 23.0% in S. 1, 4, 5, 12:i:-; 2.2%, 2.2%, 6.7% in S. anatum ; 4.5%, 1.5%, 10.6% in S. typhimurium . It was shown that the resistance rates in 1994 were significantly higher than those in 1993. All isolates were susceptible to ofloxacin with the exception of one isolate.