Antibiotic resistance pattern among the Salmonella isolated from human, animal and meat in India

The present study was conducted to study the antibiotic resistance pattern among nontyphoidal Salmonella isolated from human, animal and meat. A total of 37 Salmonella strains isolated from clinical cases (human and animal) and meat during 2008–2009 belonging to 12 serovars were screened for their antimicrobial resistance pattern using 25 antimicrobial agents falling under 12 different antibiotic classes. All the Salmonella isolates tested showed multiple drug resistance varying from 5.40% to 100% with 16 of the 25 antibiotics tested. None of the isolates were sensitive to erythromycin and metronidazole. Resistance was also observed against clindamycin (94.59%), ampicillin (86.49%), co-trimoxazole (48.65%), colistin (45.94%), nalidixic acid (35.10%), amoxyclave (18.90%), cephalexin, meropenem, tobramycin, nitrofurantoin, tetracycline, amoxicillin (8.10% each), sparfloxacin and streptomycin (5.40% each). Isolates from clinical cases of animals were resistant to as many as 16 antibiotics, whereas isolates from human clinical cases and meat were resistant to 9 and 14 antibiotics, respectively. Overall, 19 resistotypes were recorded. Analysis of multiple antibiotic resistance index (MARI) indicated that clinical isolates from animals had higher MARI (0.25) as compared to isolates from food (0.22) and human (0.21). Among the different serotypes studied for antibiogram, Paratyhi B isolates, showed resistance to three to 13 antibiotics, whereas Typhimurium strains were resistant to four to seven antibiotics. Widespread multidrug resistance among the isolates from human, animal and meat was observed. Some of the uncommon serotypes exhibited higher resistance rate. Considerable changes in the resistance pattern were also noted. An interesting finding was the reemergence of sensitivity to some of the old antibiotics (chloromphenicol, tetracycline).