Drug resistance patterns of Salmonella isolates of equine origin from India.

INTRODUCTION

Salmonellosis is a zoonosis, and one of the most serious public health and animal health problems.

METHODOLOGY: We studied 111 isolates of Salmonella belonging to 14 S. enterica subspecies enterica serovars namely S. Abortusequi (45), S. Weltevreden (1), S. Dumfries (2), S. Tshiongwe (1), S.I. 4,5,12:r,i:1,5 (12), S. Bovismorbificans (3), S. Drogana (8), S. Lagos (4), S. Kottbus (3), S. Richmond (1), S. Typhimurium (6), S. Newport (7), S. Paratyphi B var Java (17) and S. Saintpaul (5) isolated from equids in India.

RESULTS

All strains studied were resistant to one or more antimicrobials. Strains were resistant to ampicillin (18, 16%), ampicillin+cloxacillin (6, 5%), cefotaxime (6, 5%), chloramphenicol (2, 2%), ciprofloxacin (9, 8%), gentamicin (27, 24%), kanamycin (37, 33%), nalidixic acid (10, 9%), furazolidone (97, 87%), streptomycin (33, 30%), sulphamethoxazole (91, 82%), tetracycline (48, 43%) and trimethoprim (5, 4.5%). Multiple-drug-resistance was detected in 84 (75.7%) isolates and was seen in isolates of all serovars except of S. Kottbus, a rare serovar in India. Salmonella isolates could be classified into 51 resistotypes but 47 (42.3%) isolates belonged to six major resistotypes. Resistotype 13 (resistant to furazolidone, sulphamethoxazole and tetracycline) was most common, followed by resistotype 19 (resistant to nalidixic acid, sulphamethoxazole and tetracycline), resistotype 28 (resistant to furazolidone, streptomycine, sulphamethoxazole and tetracycline) and resistotype 40 (resistant to furazolidone, gentamycin, kanamycin, streptomycine, sulphamethoxazole and tetracycline) including 11, 8, 8 and 7 strains of different serovars, respectively.

CONCLUSIONS

This study revealed that antimicrobial drug resistance was common in Salmonella isolates from equids even towards those drugs not used in equids.