ANTIMICROBIAL RESISTANCE SALMONELLA ISOLATED FROM BEEF IN UPPER NORTHEASTERN THAILAND

Abstract

This study investigates the distribution of Salmonella serotypes, antimicrobial susceptibility and
patterns of multidrug resistance of Salmonella spp. isolated from beef, received from different slaughterhouses
and butcher shops in the upper northeastern region of Thailand. Amongst the beef samples, one hundred and fortyfive isolates were detected. There are three serogroups of salmonella which can be classified into eight serovars;
five serovars belonging in three serogroups were contaminated on meat from slaughterhouses, likewise, seven
serovars which included two serogroups were detected from butcher shops; by which, 12.50 % (32/145) of the
salmonella strains was resistant to antimicrobial agents and almost 6.89 % (10/145) were multidrug resistant. The
most multiresistant serotype was S. Derby, with a pattern of multi-resistance to six antibiotics, followed by S.
Rissen, S. Anatum, and S. Muenchen, respectively. Moreover, most of the salmonella strains were resistant to
ampicillin, oxytetracycline and sulfamethoxazole/trimethoprim, whilst, colistin, gentamicin, kanamycin, nalidixic
acid, and norfloxacin are considered highly susceptible drugs. In addition, these strains have been shown resistant
to chloramphenicol also, despite it has been banned use in food-producing animals. In summary, beef from the
local slaughterhouses and retail butcher shops in upper northeastern Thailand was found to be contaminated with
Salmonella spp., notably, from the serogroups B, C and E, which are multidrug resistant. For this reason,
veterinarian and all relevant authorities need to strictly regulate the use of antibiotics in animal production, whether
for use as therapy, prophylaxis, or growth promotion.