STUDIES ON SALMONELLA SEROVARS OF ANIMAL ORIGIN WITH SPECIAL REFERENCE TO FOOD BORNE SALMONELLA SEROVARS
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Date
2018-12
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SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517502. (A.P.) INDIA
Abstract
Salmonella is a foodborne pathogen having a worldwide public health concern.
The present study was undertaken to characterize Salmonella species of animal origin
based on cultural isolation, molecular confirmation of serovars, their virulence profile
and antibiogram using PCR and genetic diversity studies by employing ERIC-PCR and
REP-PCR. A total of 516 samples comprising poultry cloacal swabs (249), raw foods of
animal origin (118 chicken samples, 65 mutton and 30 pork), 17 poultry liver swabs)
and 37 poultry farm water samples were examined for presence of Salmonella serovars.
Overall prevalence of Salmonella isolates was found to be 4.06% (21/516) with
highest prevalence in chicken samples (6/118, 5.08%) followed by cloacal swabs of
poultry (12/249, 4.81%), mutton (2 /65, 3.07%) and pork (1/30, 3.33%).
All the isolates carried all the 7 virulence genes i.e. invA, invH, sopB, sopE &
stn (21/21, 100%), while pefA genes was found only in S. Typhimurium isolates and
sefC gene was found only in S. Enteritidis isolates (2).
Antibiogram of Salmonella isolates revealed 100% susceptibility to co-
trimoxazole and polymyxin–B, intermediate resistant against ampicillin (28.57%),
cefotaxime (19.04%), gentamycin (14.28%), amikacin (9.52%), ceftriaxone (9.52%),
ciprofloxacin (9.52%), tetracycline (4.76%) and streptomycin (4.76%) while higher
resistance was observed towards amikacin (61.90%) followed by ampicillin (52.30%),
tetracycline (38.09%), ceftriaxone (33.33%), gentamicin, sulfamethoxazole,cefpotaxime
and nalidixic acid (28.57% each), ciprofloxacin (23.80%), doxycycline hydrochloride
and chloramphenicol (19.04% each) and streptomycin (9.52%). Of the 21 Salmonella
isolates, 15 isolates were found resistant to β-lactam antibiotics like ceftriaxone
(33.33%), cefotaxime (28.57%), aztreonam (23.80%) and ceftazidime (23.80%) was
detected. β- lactamase genes were detected in a total of 11 isolates (11/21, 52.38%),
blaTEM being the predominant gene detected (9/11, 81.18%), followed by blaCTX-M group
II (2/11, 18.18%), blaOXA (1/11, 9.09%) and blaCTX-M group IX (1/11, 9.09%) and no
single isolate showed blaCTX-M group 1 and blaSHV genes.
ERIC PCR and REP-PCR analysis revealed a greater degree of heterogeneity
among S.Typhimurium and Salmonella group II isolates from different sources. ERIC
PCR genotyping distinguished 7 isolates each of S.Typhimurium and Salmonella group
II into 6 genotypes each whereas REP-PCR distinguished all the isolates into distinct
genotypes. The discriminatory power of ERIC-PCR and REP-PCR for Salmonella
isolates was found to be highly significant (>0.9) i.e. 0.952 and 1.0, respectively.
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