Department of Microbiology
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Item Mangrove ecosystems: An adopted habitat for pathogenic Salmonella spp.(Water Environment Federation, 2016) Poharkar, Krupali V.; Kerkar, Savita; D’Costa, Dilecta; Doijad, Swapnil; Barbuddhe, S. B.Mangroves are affected by industrial and anthropogenic factors. Although mangroves have been widely studied, investigations of pathogens that may affect public health significance are largely lacking even while incidences of diseases linked with the consumption of mangrove-associated food have increased. A total of 150 samples of water, sediment, and biota were collected from ten mangrove ecosystems in Goa, India. Total viable counts of pathogens such as E. coli, Listeria, Salmonella, and Vibrio spp. ranged from 1.25 to 3.9 × 103 cfu/ mL, which were above the relevant standards. Salmonella counts were the highest at 3.1 to 3.9 × 103cfu/mL, with a prevalence of 40%. Considering its high prevalence, the virulence of Salmonella spp. was studied. The invA gene was detected in 35% of the Salmonella isolates by polymerase chain reaction (PCR). The findings suggested that pathogens adapt to this habitat, resulting in contamination of the indigenous fauna.Item Transformation of alpha‐santonin via two independent pathways by Pseudomonas strain S ATCC 43388(Oxford University Press, 1993) Colaco, Dilecta; Furtado, I.; Naik, U. P.; Mavinkurve, S.; Paknikar, S. K.Item Isolation and Characterization of Listeria Species from Raw and Processed Meats(Indian Association of Veterinary Public Health Specialists, 2010) Doijad, S.P.; Vaidya, V.; Garg, S.; Kalekar, S.; Rodrigues, J.; D’Costa, Dilecta; Bhosle, S. N.; Barhuddhe, S. B.A total of 109 meat and meat product samples (50 beef, 52 pork sausages and 7 pork) were examined for the presence of Listeria species. Isolates were confirmed by biochemical characterization and haemolysis on blood agar. A total of 25 (22.94 percent) isolates were recovered. Of these, 7 (6.42 percent) were L. monocytogenes, while one (0.9 percent) was L. ivanovii. Other isolates were L. seeligeri (10), L. innocua (4), L. welshimeri (2) and L. grayi (1). All the isolates were further subjected to a PCR assay for detection of the hlyA gene, the hlyA gene was detected in 7 isolates. Multiplex-PCR serotyping assay revealed three of the strains belonging to serovar group 4b, 4d, 4e, and four to serovar group 1/2a, 3a. The prevalence of L. monocytogenes in raw meat, particularly serogroup 4b, 4d, 4e in present study indicates a potential threat to public health.Item Bacteriological Quality of Milk at Different Levels of Collection in Goa(Indian Association of Veterinary Public Health Specialists, 2011) D’Costa, Dilecta; Bhosle, S. N.; Dhuri, R. B.; Barbuddhe, S. B.The bacteriological quality of milk at different levels of collection was studied. Samples were collected in sterile containers at quarterly intervals. The samples were analysed for total vibal count, methylene blue reduction test (MBRT) and California mastitis test (CMT). Subclinical mastitis was found in 23.8 percent of the animals. The average methylene blue reduction time decreased from the farm to the processing unit. The average counts were 2.67x104, 1.59x104, 9.23x105 and 2.35x106 cfu/ml at farmers' field, milking utensils, collection centers and receiving dock (processing point), respectively. The milking methods, milk containers and time interval from the collection at the udder level to the receiving dock played a major role in the deterioration of the milk quality along with the climatic conditions prevalent in a particular season.Item Prevalence, Serogroups, Shiga-toxin Genes and Pulsed Field Gel Electrophoresis Analyses of Escherichia coli Isolated from Bovine Milk(Springer Nature, 2013) D’Costa, Dilecta; Bhosle, Saroj N.; Dhuri, R. B.; Doijad, S. P.; Poharkar, K. V.; Kalorey, D. R.; Barbuddhe, S. B.Shiga toxin-producing Escherichia coli (STEC) including non-O157 strains have been linked to outbreaks and sporadic cases of illness worldwide. A total of 647 milk samples were collected at different levels of collection and processing (udder, milking utensils, milk collection centres and receiving dock) within West Coast region of India. The milk samples were screened for the presence of E. coli and further tested for the Shiga-toxin (stx) genes by PCR. The isolates were characterized for their serogroups and XbaI digestion patterns of total DNA separated by pulsed-field gel electrophoresis (PFGE). A total of 77 (11.90 %) isolates were confirmed as having E. coli. The serogroups reported were O4, O60, O112, O56, O159, O120, O2, O83, O88, O95, O141, O21, O25, O80, O140, O97, O24, O166, O146, O51, O169, O147, O103, O18, O100, O15, O69, O43, O7, O3, O45, O124, O110, O84, and O114. Out of the 77 E. coli isolates, 25 (32.46 %) could be classified as Shiga-toxigenic based on PCR results. Of these 11, 3 and 11 isolates were positive for stx1, stx2, and both stx1 and stx2, respectively. PFGE profiles indicated genetic diversity of E. coli strains. Much variation was observed among isolates recovered at different levels of collection. Further research is needed to uncover unique characteristics and resistance of non-O157 STEC strains.Item Characterization of Listeria monocytogenes isolated from human clinical cases(International Journal of Medical and Health Sciences (IJMHS), 2015) Kalekar, Sushanta; Doijad, Swapnil; Poharkar, Krupali V.; Rodriguez, Savio; Kalorey, D R; Kurkure, Nitin V; Rawool, Deepak B; D'Costa, Dilecta; Bhosle, Saroj; Barbuddhe, S BIntroduction: Listeria monocytogenes is an emerging foodborne pathogen and causative agent of listeriosis. It is one of the cause of spontaneous abortions and meningitis. The objective of the study was to determine the incidences of L. monocytogenes from human cases of spontaneous abortions or having a history of spontaneous abortions and meningitis. Materials and Methods: A total of 481 samples from humans having a history of spontaneous abortions and meningitis were analyzed. Isolation of the pathogen was attempted employing two step enrichment followed by plating on selective media. Characterization of the isolates was based on biochemical tests, haemolysis on blood agar, CAMP test, phosphatidyl inositol-speciï¬ c phospholipase C assay, multiplex PCR to detect virulence-associated genes (hlyA, actA and iap) and serotyping by conventional and PCR based method. Results: Of the 481 samples analysed, 7 (1.45%) samples from abortion cases were found positive, while no CSF sample from meningitis cases was positive for L. monocytogenes. All the isolates showed in-vitro virulence characteristics such as hemolysis on 5% sheep blood agar, positive CAMP test and showed hallow formation on ALOA medium. All the isolates showed the presence of the hly, actA and iap genes. Conventional serotyping as well as PCR based serotyping revealed the isolates to be of 4b, 1/2b and 4e serotypes. Antibiotic sensitivity assay showed that the isolates were sensitive to trimethoprim, however, the isolates were least sensitive to meropenem. Conclusions: The study highlights the incidence of L. monocytogenes in humans with spontaneous abortions. KEYWORDS: Listeria monocytogenes, Serotypes, Isolation, PCR, human.Item Incidence and genetic variability of Listeria species from three milk processing plants(Elsevier, 2011) Doijad, Swapnil; Barbuddhe, S. B.; Garg, Sandeep; Kalekar, Sushanta; Rodrigues, Jenney; D’Costa, Dilecta; Bhosle, S.; Chakraborty, TrinadThe presence of Listeria in three milk processing environments as a potential source of milk contamination was assessed. Swab samples (n = 210) taken from milk processing plants were examined. Sample sites included the milk processing equipment, besides areas handling raw and pasteurized milk. The USDA Listeria-selective enrichment procedure was used to process the samples. Forty one (19.52%) Listeria isolates were recovered. The isolates were further subjected to biochemical and genotypic characterization. Out of 41 isolates, 16 (7.62%) were confirmed as Listeria monocytogenes, 2 (0.95%) as L. ivanovii, 19 (9.05%) as L. innocua. 1 (0.48%) as L. seeligeri and 3 (1.43%) as L. grayi. All the L. monocytogenes isolates were positive for the hlyA gene. PCR based serotyping revealed all L. monocytogenes to be of 1/2a, 1/2c, 3a and 3c serovar group. AscI and ApaI restriction analysis yielded four PFGE clusters for 16 L. monocytogenes isolates obtained from raw milk collector, milk silos, buttermilk mixer, cheese and other milk product processor. No predominant PFGE cluster was observed among these L. monocytogenes isolates. The main sources of L. monocytogenes were found to be raw milk collector and milk silos. In the present study L. monocytogenes was isolated from milk and milk products processing plants which could cross-contaminate the processed products and may possess a potential threat to public health.Item Potability Testing of Drinking Water from Trains on Konkan Railway Route(TamilNadu Scientific Research Organisation, 2024) Rai, Anupkumar J.; D’Costa, DilectaThe availability of drinking water is one of the primary passenger amenities provided by the railways. The present study was undertaken to investigate and evaluate the water quality of the trains plying on the Konkan railway route. The physicochemical and microbiological studies were carried out to determine the potability of water supplied by railways. The isolation and phenotypic characterization of various pathogens were mainly emphasized. All the analyzed samples showed the presence of coliforms and other organisms indicative of fecal contamination. Seasonal analysis of microbial load indicated that monsoon favours the growth and proliferation of microbes. The biochemical assessment showed the presence of several pathogens like E. coli, Salmonella spp., Vibrio spp., and Clostridium spp. This is a matter of public health concern to train commuters which in turn calls for better sanitary measures.Item Genotypic characterization of Listeria monocytogenes isolated from humans in India(Taylor & Francis, 2011) Kalekar, Sushanta; Rodrigues, Jenney; D'Costa, Dilecta; Doijad, Swapnil; Ashok Kumar, J; Malik, S. V. S; Kalorey, D. R; Hain, T; Chakraborty, T; Barbuddhe, Sukhadeo B.Listeria monocytogenes is a foodborne pathogen associated with severe diseases in humans and animals. The genotypic analysis of 17 L. monocytogenes isolates recovered from humans in India during 2006–2009 using multiplex serotyping PCR allowing serovar predictions, conventional serology and by pulsed field gel electrophoresis (PFGE) is presented. The isolates were recovered from patients exhibiting various clinical conditions. A multiplex-PCR based serotyping assay revealed 88·24% (15/17) of the strains belonging to the serovar group 4b, 4d, 4e and 11·76% (2/17) to the serovar group 1/2b, 3b. Conventional serology indicated that 13 (76·47%) L. monocytogenes isolates to be of serotype 4b, 2 (11·76%) serotype 4d, and 2 (11·76%) serotype 1/2b. Ten ApaI and nine AscI pulsotypes were recognized among the 17 human isolates. PFGE analysis allowed discrimination among isolates of the same serotype and among isolates from the same sampling areas or those isolated from different areas. Thus, PFGE together with multiplex-PCR serotyping allows rapid discrimination of L. monocytogenes strains. In addition, the predominance of L. monocytogenes serotype 4b is of concern, as this serotype has been most frequently associated with human listeriosis outbreaks.Item Rootstocks for the Management of Bacterial Wilt in Eggplant (Solanum melongena L.) and Tomato (Solanum lycopersicum L.) in the Coastal Regions of India(Hindawi, 2022) Ramesh, Raman; D’Souza, Marsha; Asolkar, Trupti; Achari, Gauri; Gupta, Mathala J.Cultivation of solanaceous vegetables such as eggplant and tomato is severely affected by bacterial wilt in the coastal regions of India. The causal agent Ralstonia pseudosolanacearum is soilborne bacterium, highly diverse, and able to survive in soil for many years without a host. Five bacterial wilt resistant eggplant (Solanum melongena) rootstock lines were evaluated by challenge inoculation and were found to show different levels of wilt incidence. Grafts of eggplant made on two rootstocks (S0004 and Surya) recorded reduced incidence of bacterial wilt (10 to 40%) during greenhouse evaluation while in nongrafted seedlings, the wilt incidence was 80 to 100%. Field evaluation of eggplant grafts made on Solanum torvum (Turkey berry), S0004, and Surya reduced the incidence of bacterial wilt compared to nongrafted seedlings. The lowest wilt incidence (0 and 15–40%) was observed in the field evaluations where S. torvum was used as rootstock, while the nongrafted control recorded 93–100% wilt. Tomato seedlings grafted on S. torvum, Surya, and S0004 recorded very low bacterial wilt incidence (0 to 15%) under greenhouse evaluation while the nongrafted seedlings recorded 80 to 100% wilt. Reduced bacterial wilt incidence (23 to 40%) was observed in grafts of polyhouse-grown tomato hybrid (GS-600) made on S. torvum while the nongrafted seedlings were severely affected (80 to 100%) in evaluation trials conducted for two years. From this study, it is evident that grafting of susceptible eggplant and tomato on resistant rootstocks, viz., S. torvum and Surya, could be a promising strategy in bacterial wilt management.Item Prevalence and characterisation of Listeria spp. from seafood(Indian Council of Agricultural Research, 2015) Rodrigues, Jenney; Kalekar, Sushanta; Doijad, Swapnil; Poharkar, Krupali; D'Costa, Dilecta; Barbuddhe, Sukhadeo B.Listeria monocytogenes, the causative organism of listeriosis, is primarily transmitted to humans through contaminated food. We examined the prevalence of L. monocytogenes isolates from fishery products marketed in Goa, India. A total of 221 raw seafood samples were examined for the presence of Listeria species following ISO 11290 protocol. Thirty seven (16.74%) samples were positive for Listeria species. Out of these, isolates from 4 (1.8%) samples were confirmed asL. monocytogenes, the remaining 33 isolates were Listeria innocua. All the isolates were subjected to PCR for the hlyAgene, which was detected in all the L. monocytogenes isolates. The isolates were also found to express phosphatidyl-inositol specific phospholipase C activity on ALOA agar. Multiplex PCR-based clonal typing revealed three L. monocytogenesisolates to be of serovar group 1/2a, 1/2c, 3a, 3c while the remaining isolates belonged to serovar group 1/2b, 3b 4b, 4d and 4e. The isolates were grouped into two AscI and ApaI PFGE (pulsed field gel electrophoresis) profiles. Prevalence ofL. monocytogenes in fresh seafood is of significance as it may contaminate and persist in the processing environment.