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Kerala Veterinary and Animal Sciences University, Wayanad

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2011 - 201926
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Subject: Veterinary Public Health × End date: 2019 × Start date: 2010 × Thesis Type: M.V.Sc. ×
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    ThesisItemOpen Access
    OCCURRENCE OF ENTEROAGGREGATIVE ESCHERICHIA COLI IN ANIMALS, HUMAN INFANTS AND ASSOCIATED ENVIRONMENTAL SOURCES IN ERNAKULAM
    (COLLEGE OF VETERINARY AND ANIMAL SCIENCES MANNUTHY, THRISSUR, 2019-09-30) MANJUSHREE T.R.; C. Sethulekshmi
    The present study was undertaken to find out the occurrence of Enteroaggregative Escherichia coli (EAEC) in young animals, human infants and associated environmental sources in Ernakulam district, Kerala. All the samples procured during a period of 12 months from August 2018 to July 2019. During the study diarrhoeic faecal sample of young animals viz., calves and piglets were collected from individual cattle and pig rearing households of two panchayats in Ernakulam district. To study the environmental association water and soil samples were also collected from the animals rearing areas. Finally to study the occurrence in human beings, infant diarrhoeic stool samples were collected from primary health care units, hospitals, anganwadis and diagnostic laboratories of Ernakulam district. The samples collected were aseptically processed by conventional cultural technique. Molecular confirmation of EAEC was done by performing polymerase chain reaction (PCR) that targeted conserved genus specific 16SrRNA gene and virulence genes viz., astA, Pic, aggR and fimA genes with amplicon size 231, 106, 1111, 251 and 342 bp, respectively. The isolates were subjected to biofilm assay using a 96-well microtitre plate. To understand the antibiotic resistance profile, all the isolates were subjected to standard disc diffusion method for commonly used antibiotics. Thus the study gives information regarding occurrence of EAEC in the Ernakulam district and the risk associated with it. All the procured samples were initially subjected to isolation of E. coli through conventional cultural and biochemical techniques and E. coli could be recovered from 51and 42 samples of calves and piglets respectively. From the environmental samples, 30 soil samples and 62 water samples showed positive for E. coli. Among the human infants samples, 39 samples revealed positive for E. coli. All the 224 E. coli isolates were subjected to a genus specific 16SrRNA which affirmed that all the isolates belong to the genus Escherichia. All these E. coli isolates were further subjected to PCR for the detection of virulence associated genes belonging to EAEC. Four oligonucleotide primers targeting the EAEC viz., heat-stable toxin (astA), mucinase (Pic), transcriptional activator aggregative gene (aggR) and fimbrial subunit gene (fimA) were used in the study for detection of EAEC. On analysis 21.57 per cent, 5.89 per cent, 5.89 per cent and 15.69 per cent of the E. coli isolates from calf diarrhoeal samples carried the astA, pic, aggR and fimA genes respectively. From the piglets’ diarrhoeal samples, astA, pic, aggR and fimA genes were detected from 9.52 per cent, 9.52 per cent, 4.76 per cent and 23.81per cent of E. coli isolates respectively. From water and soil samples of calves rearing areas seven E. coli isolates carried virulence genes. Of the piglets rearing areas only two isolates from water carried the virulence genes where as soil samples remained negative. Out of 39 E. coli isolates from human infant diarrhoeal samples 20.51 per cent, 7.69 per cent, 7.69 per cent and 17.94 per cent carried astA, pic, aggR and fimA genes respectively. To study the biofilm forming ability, all the EAEC isolates were subjected to quantitative biofilm assay through which it was inferred that the 84 and 78.57 per cent of isolates from calves and piglets were low biofilm producers whereas only 10.5 and 7.14 per cent showed high biofilm forming ability. None of the isolates from environmental sources showed high biofilm forming ability. From human infants only two isolates showed high biofilm forming ability whereas 81.2 per cent were low biofilm producers. On antibiotic sensitivity study, EAEC isolates from calves showed highest resistance towards ampicillin (84 per cent) followed by cefotaxime (57.89 per cent). Among the isolates from piglets resistance was observed with cefotaxime and tetracycline (79 per cent). From environmental sources norfloxacin (78 per cent), cefotaxime and tetracycline (77.7 per cent) showed highest resistance. In human infants EAEC isolates showed highest resistance against ampicillin, streptomycin (75 per cent) and azithromycin (68.75 per cent). All the isolates were sensitive to imipenem. Further sensitivity was observed among nitrofurantoin and meropenem. From the study it was concluded that EAEC is an emerging pathogen of public health importance because of its ability to form biofilm and increasing antibiotic resistance towards commonly used antibiotics.
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    ThesisItemOpen Access
    OCCURRENCE OF COMMUNITY- ASSOCIATED AND LIVESTOCK- ASSOCIATED METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS FROM COMPANION ANIMALS, LIVESTOCK AND THEIR HANDLERS
    (COLLEGE OF VETERINARY AND ANIMAL SCIENCES, POOKODE WAYANAD, 2019-12-21) HAKIM, HAMNA
    Antimicrobial resistance (AMR) is one of the leading threats in healthcare management system. Staphylococcus aureus is a commensal bacteria commonly seen on skin and nasal passage that can turn as an opportunistic pathogen. Resistance observed in S.aureus is among the first reported cases of AMR. Methicillin Resistant Staphylococcus aureus (MRSA) has spread and proved fatal among human and animal populations around the globe. MRSA was initially reported as healthcare-associated (HA-MRSA), community-associated (CA-MRSA) and livestock-associated MRSA (LAMRSA). Hence, the present study was carried out to evaluate the nasal carriage of CAMRSA and LA-MRSA among apparently healthy companion animals, livestock and their handlers. A total of 220 nasal swabs were collected from dogs (30), cats (30), cattle (40), goats (30), pigs (30) and human handlers (60) including animal owners (20), farm workers (20) and veterinarians (20). All the samples were initially screened for occurrence of S.aureus, which was confirmed by PCR using species specific primer (nuc). All the S.aureus isolates were screened for the occurrence of MRSA, both phenotypically (double disc diffusion using cefoxitin and oxacillin discs) and genotypically (PCR employing mecA and mecC). There was a significant difference in the nasal carriage of S.aureus among animal population ( Chi-square value – 33.206, pvalue < 0.001), which was found as 76.67 per cent, 23.33 per cent, 53.33 per cent, 62.5 per cent, 86.67 per cent, and 71.67 per cent among dogs, cats, cattle, goats, pigs and human handlers respectively. None of the nasal swabs from animals were found positive for MRSA. Among the human handlers, there was no significant difference in nasal carriage of S.aureus (Chi-square value – 1.149, p-value = 0.563). Three human handlers (two farm workers and one veterinarian) were alone positive for MRSA, with a five per cent occurrence rate. All the MRSA isolates were also screened for the presence of virulent gene, pvl. None of the MRSA isolates harboured virulent pvl gene. Later, the molecular typing of MRSA isolates were done by spa typing. Two of the three recovered MRSA isolates belonged to the spa type t18050 and one isolate was spa type t18230. The present study signifies the prevalence of nasal carriage of S.aureus and MRSA among occupationally at risk humans and the absence among domestic animal population of Wayanad district.
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    ThesisItemOpen Access
    OCCURRENCE OF SELECTED ENTERIC BACTERIAL PATHOGENS OF PUBLIC HEALTH SIGNIFICANCE FROM COMPANION ANIMALS AND URBAN DWELLING BONNET MACAQUES
    (COLLEGE OF VETERINARY AND ANIMAL SCIENCES, POOKODE WAYANAD, 2019-09-27) N., SUMA
    Zoonotic diseases are a major public health threat that can spillover to human from non-human primates and companion animals due to their close association. The spillover of bacterial enteropathogens such as E. coli, Salmonella spp., Shigella spp. and Y. enterocolitica can cause severe and chronic gastrointestinal illness. Hence, the present study is envisaged to evaluate the occurrence and characterization of above pathogens from dogs, cats and bonnet macaques of Wayanad district and to characterize its virulence potential and ESBL resistance. A total of 150 faecal samples/ faecal swabs from dogs (50), cats (50) and bonnet macaques (50) were analyzed for enteric bacterial pathogens through conventional culture and molecular method using 16S rRNA PCR-RFLP. The occurrence of E. coli, Salmonella, Shigella spp. and Y. enterocolitica was recorded in 107, 31, 6 and 21 samples, respectively and macaques were identified as a major source. PCR-based virulent gene characterization revealed that 20 per cent of isolates were positive for EHEC (eaeA, stx1), 36 per cent of isolates were EAEC (aggR, fimA), 7 per cent were Salmonella (invA, stm), 4 per cent were Shigella (ipaH) and 14 per cent of samples were Y. enterocolitica (ystA). Further, characterization of isolates for ESBL production through phenotypic disc diffusion method and genotypic PCR assays revealed that 77.77 per cent of E. coli isolates were ESBL producers and ESBL gene that could be identified in majority of isolates was blaCTX-M. With regard to the ESBL characterization of other isolates, 22.58 per cent samples were identified as ESBL producers in case of Salmonella spp. and the most common ESBL genes identified were blaSHV and blaTEM. Only few isolates of Shigella spp. and Y. enterocolitica were recovered from dogs and macaques samples, some of which were ESBL producers. Thus, a diverse genotypic pattern of ESBL resistance was observed among isolates. The present study signifies the occurrence of enteric bacterial pathogens among pet and wild animals, its virulence nature and the ability to harboring ESBL resistance genes and its dissemination.
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    ThesisItemOpen Access
    MITIGATION OF ENTEROHAEMORRHAGIC ESCHERICHIA COLI ON MEAT CONTACT SURFACES USING PHYTOCHEMICALS
    (COLLEGE OF VETERINARY AND ANIMAL SCIENCES-MANNUTHY,THRISSUR, 2018) THORAT AJAY BALKRISHNA; C. Sethulekshmi
    The present study was undertaken to study the occurrence of Enterohaemorrhagic E. coli (EHEC) on meat contact surfaces from retail meat outlets. A detailed study was also done regarding the biofilm forming ability of EHEC isolates and the effect of phytochemicals viz., trans-cinnamaldehyde and eugenol in reducing the growth of EHEC on meat contact surfaces. The antibiofilm effect of these phytochemicals was analysed. A total of 245 swab samples comprising of meat cutting board and knife surfaces were collected from four retail meat outlets located in and around Thrissur district during the period of study from November 2017 to June 2018. All the swab samples were subjected to isolation and identification of E. coli and Enterohaemorrhagic E. coli by conventional culture technique. The characteristic colonies from Cefixime Tellurite-Sorbitol MacConkey Agar were selected and inoculated into tryptic soya broth (TSB). The broth culture was subjected to multiplex PCR for detecting the virulence genes viz., stx1, stx2, eaeA and hlyA. A total of 40 EHEC isolates comprising of 30 isolates from cutting board and 10 isolates from knife surfaces were obtained. The occurrence of EHEC recorded from four retail meat outlets was 12 per cent, 21.42 per cent, 18.88 per cent and 5.71 per cent respectively. The higher occurrence was recorded from second retail meat outlet (21.42%) in comparison with other retail outlets from Thrissur district. All the 40 positive isolates were analysed for its biofilm forming ability and of which only five per cent of isolates had biofilm forming ability. Further, minimum inhibitory concentration (MIC) of phytochemicals was determined against biofilm producing EHEC and the MIC for trans-cinnamaldehyde and eugenol was found to be 3.5 per cent and 5.5 per cent respectively. The effect of these phytochemicals in reducing the growth of EHEC on meat contact surfaces was also analysed. The two concentrations of each phytochemical was studied. A concentration of 3.5 per cent and 4.0 per cent of trans-cinnamaldehyde brought about 0.66 and 0.69 log10 cfu/ml reduction of EHEC organisms on wood in comparison with control of 5.42 log10 cfu/ml respectively. Eugenol at 5.5 per cent and 6.0 per cent showed total reduction of EHEC organisms on wood. To study the anti-biofilm effect of these phytochemicals, EHEC biofilms were artificially created on wodden and fiber surfaces and the effect of two different concentrations of each phytochemical were tested. A concentration of 3.5 per cent of trans-cinnamaldehdye and 5.5 per cent of eugenol showed reduced growth of EHEC biofilm whereas concentrations of 4.0 per cent of trans-cinnamaldehyde and 6.0 per cent of eugenol completely inhibited biofilm forming EHEC. Hence these phytochemicals can be used as a good sanitizers in order to reduce the growth of EHEC which also had a significant effect on its biofilm forming ability.
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    ThesisItemOpen Access
    DETECTION AND QUANTITATION OF RESIDUES OF COMMONLY USED ANTIBIOTICS IN RAW MILK
    (COLLEGE OF VETERINARY AND ANIMAL SCIENCES-MANNUTHY,THRISSUR, 2018) KUMARSWAMY N P; C. LATHA
    The present study was undertaken to detect and quantitate the residues of commonly used antibiotics in raw milk in Thrissur district of Kerala. The cross sectional survey was conducted among the farmers to assess their knowledge and awareness level on the use of antibiotics. A total of 440 milk samples were collected from ULF and FRDS, Mannuthy, private farms in Thrissur and individual households during the period from August 2017 to July 2018. All the samples collected were subjected for screening of antibiotic residues by microbial inhibition assay (MIA). The positive samples were analysed by Charm assay to determine the group and level of antibiotic residues. The amount of residues of oxytetracycline, enrofloxacin and cloxacillin in positive samples was quantitated using High Performance Liquid Chromatography (HPLC). The survey among the farmers showed that 78 per cent of people were aware of the antibiotic use and 43 per cent of people had knowledge about the withdrawal period. The most commonly used antibiotics were oxytetracycline (54 per cent), ßlactams (44 per cent), enrofloxacin (36 per cent), sulphonamides (14 per cent) and gentamycin (12 per cent). Of 440 milk samples screened by MIA, the antibiotic residues were detected in 7.41, 18.57 and 13.33 per cent of samples from ULF and FRDS, private farms and individual households respectively. The overall occurrence rate of antibiotic residues observed was 13.18 per cent. On analysing 58 positive samples in MIA by Charm Rapid One Step Assay (ROSA), it was found that 2.95 per cent of samples were positive for tetracyclines residues, 3.64 per cent of samples for enrofloxacin residues and 2.27 per cent of samples for ß-lactams residues. The HPLC conditions, sample extraction and analytical methods for detection and quantitation of oxytetracycline, enrofloxacin and cloxacillin residues were optimized and validated. The analysis of oxytetracycline was carried out on C18 column using a mobile phase of 0.03 M Oxalic acid : Acetonitrile : Methanol (70: 15 : 15) delivered at a flow rate of 1 ml/min. Photodiode array detector was set at 354 nm for oxytertracycline detection. The mobile phase consisting of 0.1 M Orthophosphoric acid (pH adjusted to 2.5 with triethylamine): Acetonitrile: Methanol (80:17:3) was used for enrofloxacin detection on C18 column. Flow rate of 0.8 ml/min and detection wavelength of 278 nm were found to be optimal. Chromatography conditions of cloxacillin consisted mobile phase of 0.1 per cent Trifluroacetic acid: Acetonitrile (50:50), flow rate of 1 ml/min and detection wavelength of 210 nm. The retention time noticed for oxytetracycline, enrofloxacin and cloxacillin was 5.6, 7.7 and 7.48 min respectively. A good linearity with coefficient of determination greater than 0.99 was obtained for all antibiotics. Of the 13 samples tested by HPLC for oxytetracycline, 12 samples showed oxytetracycline residues with a mean concentration of 1450.20 ± 182.09 ng/ml. Enrofloxacin was detected in all the 16 samples tested by HPLC with highest concentration of 709.28 ng/ml. Cloxacillin could be dectected only in two samples out of ten samples tested by HPLC with mean concentration of 118.77 ± 29.76 ng/ml. The presence of antibiotic residues in edible tissues of animals can cause adverse effects in human health and also lead to development of antimicrobial resistance which is one of the most serious global public health threats in this century. Thus, judicious and proper use of antibiotics, strict adherence to withdrawal period and maintenance of treatment records are the necessary steps to prevent the occurrence of antibiotic residues in milk. Control of antibiotic residues in foods of animal origin needs strict monitoring and surveillance studies so as to discard the food products that are not safe for human consumption.
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    ThesisItemOpen Access
    OCCURRENCE OF CAMPYLOBACTER SPP. IN SWINE PRODUCTION FACILITIES AND PORK PROCESSING LINES
    (COLLEGE OF VETERINARY AND ANIMAL SCIENCES-MANNUTHY,THRISSUR, 2018) MURALIKRISHNA P; B. SUNIL
    The present investigation was undertaken to determine the occurrence of Campylobacter spp. in swine production facilities, pork processing line, molecular confirmation and antibiotic resistance profile of the positive isolates. Comparative analysis regarding occurrence, weekly prevalence and antibiogram of Campylobacter spp. in piglets from both farms. The study also assessed the multiple drug resistant (MDR) and multiple antimicrobial resistance index (MAR) of the isolates. A total of 505 samples comprising of 340 rectal swabs from pigs and piglets, 40 faecal samples of pigs, 20 wild bird faecal droppings, 20 samples each feed, drinking water, wallowing tank water, soil and worker’s hand swabs and foot swabs were collected from two farms (F1 and F2) in Thrissur. In addition, five samples which includes three dog rectal swabs and two human faecal samples were collected from F1. To establish critical control points and to identify contamination points in pork processing line, a total of 484 samples was screened from various points of pork processing line from processing units, M1 and M2. All the samples were subjected to isolation and identification by conventional culture technique. Confirmation and species level identification was done by multiplex polymerase chain reaction. The antibiotic resistance profiling and multiple antimicrobial resistance index (MAR) analysis was carried out for all the positive isolates. Higher occurrence of Campylobacter spp. was recorded from F1 (33.3 per cent) when compared to F2 (21.70 per cent). From both the farms, piglets started excreting Campylobacter from fourth week after birth. Higher occurrence of Campylobacter spp. was recorded from F1 where 33.33 per cent of piglets selected for study excreted organisms from fourth week, while only 20 per cent of piglets from F2 were excreting Campylobacter spp. By the end of tenth week, occurrence of Campylobacter coli from both the farms were almost similar with 66.67 per cent of piglets positive from F1 and 60 per cent from F2. Shedding pattern of Campylobacter spp. in piglets was regular from F1, while irregular shedding pattern was recorded from F2. Higher occurrence of Campylobacter spp. was noticed in pigs (37.5 per cent), house crows and egrets (30 per cent), workers hand swabs and foot swabs after operations (40 per cent) and food waste mixed with raw chicken waste (20 per cent) from F1. Lower occurrence was noticed in F2, with pigs and crows having an occurrence of 20 per cent. Higher occurrence of Campylobacter spp. was noticed from environmental samples obtained from F2 with an occurrence of 20 per cent from wallowing tank water and soil samples while F1 had an occurrence of 16 per cent. Migratory pathway of infected wild reservoirs resulted in cross-transmission among birds and pigs. On analysis of contamination points from both the processing units, pigs brought to slaughter was the prime source of contamination for Campylobacter coli. From both the units, pigs carried the organism after stunning till scalding. No organisms could be detected after scalding. In M1 Campylobacter coli could be detected from carcass swabs obtained from jowl and belly after evisceration. Organisms could be also detected from carcass swabs after splitting of carcass. From M2, Campylobacter coli could not be detected after scalding till packing. In M1, meat samples which were positive before freezing were negative after freezing at -20°C for 24 hours. So freezing temperature could be considered as a CCP2 in M1 while scalding can be considered as a CCP2 in M2. All the C. coli isolates showed higher resistance against multiple antibiotics with cent per cent resistance against Ceftazidime, Co-trimoxazole and Ofloxacin. Cent per cent of the C. jejuni isolates showed resistance against Ceftazidime. Difference in resistance pattern was noticed in swine production system based on management practices followed in production facilities. In antibiotic free systems (F1) there was less prevalence of resistant strains compared to farms using antibiotics (F2). The multiple antimicrobial resistance (MAR) index of isolates was in the range of 0.21-0.87, with maximum number of isolates showing resistance for more than three groups of antimicrobials and pigs acting as a major source of multiple drug resistant strain of Campylobacter spp. (86.95 per cent). Thus proper implementation of biosecurity measures and bio containment in swine production systems will reduce the risk of Campylobacter infections and promote food safety through farm to fork concept. Control of foodborne diseases and emergence of multidrug resistance Campylobacters requires a multifaceted one health approach and surveillance programmes.
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    ThesisItemOpen Access
    IDENTIFICATION OF CAMPYLOBACTER SPP. CRITICAL CONTROL POINTS IN BEEF PRODUCTION CHAIN
    (COLLEGE OF VETERINARY AND ANIMAL SCIENCES-MANNUTHY,THRISSUR, 2018) VANI R. PILLAI; K. Vrinda Menon
    The present study was undertaken to identify the critical control points of Campylobacter spp. in beef production chain. The study also assessed the antibiotic resistance profile of the isolates. A total of 500 samples were collected from two meat processing plants and University Livestock Farm and Fodder Research Development Scheme, Mannuthy (ULF and FRDS) during November 2017 to May 2018. The critical control points in the beef production chain to confine the occurrence of organism in beef were also investigated. All the samples were subjected to isolation of Campylobacter spp. by conventional cultural technique. The samples were also subjected to direct PCR using the genus specific 16S rRNA gene, C. jejuni specific mapA gene, C. coli specific ceuE gene and virulence gene cadF. The antibiotic sensitivity test of the positive isolates was performed using standard disc diffusion method to find out antibiotic of choice in treatment. Out of 236 samples examined from ULF & FRDS, Mannuthy, four per cent dung samples were found to have Campylobacter spp. by culture technique. The overall occurrence of Campylobacter spp. in ULF & FRDS was found to be 5.94 per cent by PCR. The samples (264) from different stages in the beef processing line of two meat processing plants were also assessed for detection of Campylobacter spp. The occurrence rate of Campylobacter spp from meat processing plant I and II was found to be 9.16 and 15.9 per cent respectively. As, process of dehiding and evisceration helps to reduce the microbial load, they were identified as critical control points (CCP2). Animal, floor surface, operator hands, water, knife, table surface are the critical points of contamination noticed in the present study. The confirmed isolates were sensitive to amikacin, amoxycillin, chloramphenicol, ciprofloxacin, clindamycin, dorepenem, doxycycline, gentamicin, imipenem and meropenem while they were resistant to cefixime, cefotaxime, cefuroxime, ceftazidime, enrofloxacin and tetracycline. Hygienic practices throughout the rearing, transportation and slaughtering of cattle should be adopted to eliminate contamination of beef with Campylobacter spp.
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    ThesisItemOpen Access
    CHARACTERISATION AND ANTIBIOGRAM PROFILE OF ESCHERICHIA COLI AND STAPHYLOCOCCUS AUREUS ISOLATED FROM BOVINE MASTITIC MILK
    (COLLEGE OF VETERINARY AND ANIMAL SCIENCES, POOKODE WAYANAD, 2015) SUNITHA. R; Vinod V. K
    Mastitis is one of the economically important disease throughout the world. Subclinical mastitis is characterized by no structural changes in udder or consistency of milk is a significant public health hazard as the mastitic milk enters the human food chain as normal milk (Hameed et al., 2006). Heat stable enterotoxins produced by the pathogenic bacteria, antimicrobial resistance and antibiotic residues which are associated with mastitis makes it public health significance day by day. The study was undertaken for a period of 10 months from June 2014 to March 2015 during which a total of 100 mastitic milk samples both from clinical and sub-clinical mastitic cases identified by California Mastitis Test (CMT) and changes in the consistency of milk and udder were collected. Epidemiological investigation of the zoonotic bacteria present in mastitic milk was carried out for a total of 100 samples each of dung and udder wash and 50 each of milker’s hand wash, fodder, water and soil samples were collected from three different regions namely, Thariyode and Pozhuthana panchayaths and Kalpetta Municipality. A total of 62 mastitic samples were found positive for S. aureus of which 21 were obtained from Kalpetta, 23 from Thariyode and 18 from Pozhuthana. Seven S. aureus isolates were found positive for MRSA. E. coli was isolated from 51 mastitic milk samples which included 24 from Kalpetta, 20 from Thariyode and seven from Pozhuthana. L. monocytogenes was detected in six mastitic milk samples with three, two and one from Kalpetta, Thariyode and Pozhuthana respectively. Salmonella spp. was isolated from three mastitic milk samples, two from Kalpetta and one from Pozhuthana. The antibiotic sensitivity revealed that isolates were found highly sensitive to ciprofloxacin, ceftriaxone and chloramphenicol, moderately sensitive to gentamicin, streptomycin and tetracyclin but found resistant to methicillin, ampicillin, amoxyclav and vancomycin.
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    ThesisItemOpen Access
    COMPARATIVE EFFECT OF BACTERIOPHAGE AND NISIN ON Listeria monocytogenes IN CHICKEN AND FISH
    (COLLEGE OF VETERINARY AND ANIMAL SCIENCES-MANNUTHY,THRISSUR, 2014) SAJU GEORGE; K Vrinda Menon
    In the present study, isolation of Listeria monocytogenes from chicken, fish and sewage was undertaken to understand its prevalence using standard culture method and confirmation by polymerase chain reaction (PCR). About 60 samples of chicken were collected and screened for the evaluation of the L. monocytogenes and none of the samples were found positive. Out of the 60 samples of fish collected from retail outlets from markets of Thrissur, Kozhikode and Palakkad, 5 samples were found positive for Listeria spp and out of which one isolate was confirmed as L.monocytogenes. The other four samples were confirmed as L.innocua. All positive samples were obtained from the municipal markets of Kozhikode. A total of 110 samples of sewage were screened for the presence of L. monocytogenes and three positive samples were obtained and the isolates were confirmed as L.innocua using PCR. The prevalence rate of Listeria in sewage was found to be 8.33 per cent. Sewage samples (110) were screened for the presence of Listeria specific bacteriophages and plaques could be isolated from 18 samples. The standardisation of PCR for the isolates was done using lysZ5gene. However, none of the isolated samples were found positive to this gene and was detected only in the standard culture (ATCC23074 B1). Comparative effect of bacteriophage and nisin on L.monocytogenes in chicken and fish were assessed. Bacteriophage (103 pfu/ml) and nisin (1 per cent) was added on the substrates at 10µl, 20µl and 30µl levels. Bacteriophage at 20µl level could completely inhibit the growth of L.monocytogenes on day 14 and day 7 of storage in chicken and fish respectively. But on addition of 30µl of nisin complete inhibition of bacteria was observed on 14th and 3rd day of storage in chicken and fish. However regrowth of bacteria was observed on further storage upto 21 days. Hence these antimicrobial substances have a great potential to control the growth of bacteria in foods. 86 Annexures