K. N. Bhilegaonkar

Effect of nisin and its combination with sodium chloride on the survival of Listeria monocytogenes added to raw buffalo meat mince

Antilisterial activity of nisin (Nisaplin), alone at concentrations of 400 and 800 IU/g and in combination with 2% sodium chloride was incorporated in raw buffalo meat mince. Samples of the raw meat mince were inoculated with 10(3) colony forming units (cfu)/g of L. monocytogenes and stored at 4°C for 16 days and at 37°C for 36 h. Initial estimates of pH, extract release volume, mesophilic and psychrophilic counts were found to be 5.74, 48 ml, 3.5×10(5) and 1.0×10(5) cfu/g of meat, respectively. The growth of L. monocytogenes in the treated groups was significantly (P<0.05) inhibited compared to the control group. The degree of inhibition increased with increasing concentration of nisin and decreasing storage temperature. Addition of 2% sodium chloride in combination with nisin increased the efficacy of nisin at both storage temperatures. The pH in the treated groups remained significantly lower (P<0.01) than in the control groups at both 4 and 37°C.

Occurrence of Campylobacter jejuni in vegetables.

In order to understand the importance of vegetables in the transmission of thermophilic Campylobacter, 56 samples of different vegetables were screened. Out of these, 2 samples (1 spinach and 1 fenugreek) revealed the presence of Campylobacter jejuni biotype I. Both the isolates were enteropathogenic in rat ileal loop test.

Prevalence of Q fever in domestic animals with reproductive disorders.

The occurrence of Coxiella burnetii in animals with reproductive disorders was studied. A total of 920 samples (genital and faecal swabs, milk, urine and serum) were collected from cows (88), buffaloes (33), sheep (43) and goats (53) with a history of reproductive disorders and screened for C. burnetii by a PCR assay targeting the repetitive transposon-like region of C. burnetii (trans-PCR), real-time PCR, indirect immunofluorescence assay (IFA), enzyme-linked immunosorbent assay (ELISA) and isolation method. The overall prevalence of Q fever in animals with the history of reproductive disorders turned out to be 13.82%. The species-wise prevalence of Q fever among animals was observed to be 12.78% in cattle, 16.66% in buffaloes, 11.04% in sheep and 6.13% in goats. In comparison to IFA, the highest sensitivity (85.18%) was shown by both PCR assays followed by ELISA (74.07%) and isolation method (14.81%) whereas, isolation method was the most specific (100%) followed by both PCR assays (99.47%) and ELISA (98.44%). The high excretion rate of pathogen particularly in milk observed in the study posses a potential public health threat from infected animals.

Species identification of clinically important Aeromonas spp. by restriction fragment length polymorphism of 16S rDNA

Aims:  The aim of the study was to characterize 16S rDNA of Aeromonas spp. to rapidly identify clinically important species of these bacteria.

Use of a phospholipase-C assay, in vivo pathogenicity assays and PCR in assessing the virulence of Listeria spp.

Listeria spp. was isolated from 19.8% of animals with a history of reproductive disorders. A total of 333 faecal, genital swab and blood samples from 111 animals (cattle, buffaloes, sheep and goats) were subjected to PCR to detect virulence-associated genes (prfA, plcA, hlyA, actA and iap) and pathogenicity testing by the phosphatidylinositol phospholipase-C (PI-PLC) assay, and by mouse and chick embryo inoculation. One isolate of Listeria ivanovii recovered from a genital swab from a sheep was found to be pathogenic. Virulence assessment was then carried out on two L. ivanovii and 29 Listeria monocytogenes isolates from various sources using these assays. Haemolytic L. monocytogenes isolates lacking the plcA gene and PI-PLC activity were deemed non-pathogenic when assessed by mouse and chick embryo inoculation tests, in spite of having the hlyA gene. The results suggested that the PI-PLC and PCR assays are reliable in vitro alternatives to in vivo pathogenicity tests for L. monocytogenes.

Antimicrobial resistance and typing of Salmonella isolated from street vended foods and associated environment

AbstractThe present study was carried out to find out the occurrence and types of Salmonella present in street vended foods and associated environment, and their resistance pattern against various antibiotics. About 1075 street vended food and associated environment samples were processed for isolation and confirmation of different Salmonella spp. by targeting gene specific invA gene and serotype specific Sdf I, Via B and Spy genes by PCR. Selected Salmonella isolates were screened for antibiotic resistance by using Baeur–Kirby disk diffusion test. Out of 1075 samples, only 31 (2.88%) isolates could be amplified the invA gene of which 19 could be recovered from meat vendors; 8 from egg vendors while remaining 4 from milk vendors. Though, majority of Salmonella recovered from raw foods the ready-to-eat food like chicken gravy and rasmalai also showed its presence which pose a serious public health threat. Overall, 19, 6 and 1 isolates of S. Typhimurium, S. Enteritidis and S. Typhi could be detected by PCR while remaining 5 isolates could not be amplified suggesting other type of Salmonella. Selected Salmonella isolates were completely resistance to Oxacillin (100%) followed by Cefoxitin (30.43%) and Ampicillin (26.10%). Thus, it is observed that the street vended foods of animal origin and associated environment play an important role in transmission of food borne pathogens including Salmonella.

Cloning and sequencing of biofilm-associated protein (bapA) gene and its occurrence in different serotypes of Salmonella

Aims:  Salmonella spp. has the capability to form biofilm on various surfaces. Biofilm‐associated protein (bapA), a large surface protein has been shown to play a leading role in the development of biofilm in Salmonella. Objective of this study was to investigate the presence of bapA gene in different serotypes of Salmonella spp. and to characterize DNA fragment encoding bapA protein of Salmonella Enteritidis.

Street Vended Foods and Associated Environment in Two Major Cities of India: Microbial Safety Concern

Majority of the people in the cities liked to have street food even with the compromising their health. Therefore, the present study was carried out to find out the microbiological profile/safety of street vended foods and associated environmental samples collected from Mumbai and Delhi. A total of 166 samples of foods of animal origin (124) and associated environmental samples (42) were processed for aerobic plate count, enumeration of Escherichia coli, Staphylococcus spp., sulphite reducing Clostridia (SRC) and for detection of Salmonella spp. and Listeria monocytogenes, while water samples tested for most probable number. Swab samples showed low to marginal APC for Delhi while marginal to high in Mumbai. Notably, E. coli and Staphylococcus spp. count is higher in table and cloth swabs. Overall, 42.4%, 69.6% and 51.5% swab samples were positive for E. coli, Staphylococcus spp. and SRC, respectively. APC for raw chicken was 5.00 ± 0.17 & 5.45 ± 0.05 log10cfu g-1 for Mumbai and Delhi, respectively while that of 4.13 ± 0.18 and 4.53 ± 0.10 log cfu g-1 for raw egg and raw milk from Delhi and 4.00 log cfu g-1 for raw egg from Mumbai. Salad and chutney samples showed marginal to high APC (3.5 to 4.7 log cfu g-1) with the presence of E. coli and Staphylococcus spp. in majority of the samples in both the cities. Overall, 38.75, 51.25 and 35.0% raw foods; 52.0, 36.0 and 8.0% milk products and 22.72, 31.81 and 13.63% cooked food samples were positive for E. coli, Staphylococcus spp. and SRC, respectively. Salmonella spp. was present in only one chutney sample while L. monocytogenes was absent in all. Cooked chicken from Mumbai had 1.89 ± 0.56 log cfu g-1 with mean E. coli and Staphylococcal count is

Indirect ELISA for serosurveillance of japanese encephalitis in pigs

For monitoring the activity of Japanese encephalitis (JE) in pigs, no effective assay is available in Indian context. Being its endemicity in India and role of pigs as amplifiers, there was need to develop rapid and sensitive assay for serosurveillance of JE in pigs. An Indirect ELISA (I-ELISA) was standardized using ultracentrifuge sucrose density gradient purified JE antigen from standard virus strain. Cross reaction studies were done with West Nile antigen and comparative efficacy of I-ELISA assessed with Virus Neutralization Test (VNT). Optimum results recorded for detection of IgG and IgM, respectively, at 50 ng/well antigen and 1:200 and 1:300 serum dilutions. The positive - to - negative ratio of ³2 considered positive for JE antibodies. The overall prevalence of JE in pigs recorded to be 28.89 %. The concordance of the indirect ELISA (IgG) vis-a-vis VNT revealed good agreement (kappa = 0.66) and moderate agreement (kappa = 0.56) of standardized I- ELISA towards detection of IgG and IgM, respectively. The assay standardized in the present study could be useful for JE serosurveillance in pig population from endemic and non endemic areas in India.

Food Safety Assurance Systems: Good Animal Husbandry Practice

Good husbandry practices at farm level form an essential component of the production of quality and safe food. It encompasses all the measures adopted at the farm, from procuring and rearing healthy animals, their welfare, to final slaughter or milking. Farm management is done in such a way as to keep animals in a healthy condition, provide adequate and contamination-free feed and water and optimum living conditions. Animals are raised on the basis of risk analysis and control of these risks is exercised for safe food production. Proper records are maintained for easy traceability.