A study on biotyping, bacteriocin typing and drug resistogram of Salmonella paratyphi b isolates from animals, their products and environment
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In this study 39 isolates of Salmonella Paratyphi B from animals/environment and one of human origin were characterized to understand epidemiological distribution of this pathogen. Of the 40 isolates under the study, 24 belonged to S. Paratyphi B var java (utilizing d–tartrate) and 16 were S. Paratyphi B (not utilizing d–tartrate). Fermentation of xylose and sorbitol and production of DNase were able to further subtype the two groups of S. Paratyphi B (classical– SPB, and var Java–SPBJ). Among 24 isolates of SPBJ, 6 biovars namely, biovar I (xylose+, sorbitol+, DNase+) 15 isolates, biovar II (xylose+, sorbitol+, DNase-) 2 isolates, biovar III (xylose-, sorbitol+, DNase+) 2 isolates, biovar IV (xylose-, sorbitol+, DNase-) 2 isolates, biovar V (xylose+, sorbitol-, DNase+) 2 isolates and biovar VI (xylose-, sorbitol-, DNase+) one isolate, could be identified. Isolates of biovar II to VI were isolated only from Mumbai. Of the 16 SPB isolates, 11 (10 from fish and 1 from khoa) belonged to biotype I while remaining 5 (1 pork, 2 sewage, 1 fish and 1 human) to biotype II. Multiple drug resistance (MDR) pattern of S. Paratyphi B isolates revealed their resistance to dicloxacillin, cefazolin, colistin and ceftazidime and sensitiveness to augmentin, ciprofloxacin, nalidixic acid, enrofloxacin, tetracycline, lomefloxacin, crystal violet, acriflavin and mercuric chloride. Other frequently resisted drugs were nitrofurantoin (17 SPBJ and 9 SPB), streptomycin (2 SPB and 9 SPBJ) and cephalexin (1 SPBJ and 7 SPB). No correlation could be found out between biovar and antibiogram of different isolates. All the SPB strains were of same bacteriocin type while 24 SPBJ isolates could be classified into 5 bacteriocin types. Bacteriocin type I was the predominant (19 isolates) and prevalent all over India while other four bacteriocin types (II, III, IV and V) were prevalent only in Mumbai. The study revealed the significance of bacteriocin typing, biotyping and resistogram in understanding the epidemiology of paratyphoid infection in India.