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Assam Agricultural University, Jorhat
Assam Agricultural University is the first institution of its kind in the whole of North-Eastern Region of India. The main goal of this institution is to produce globally competitive human resources in farm sectorand to carry out research in both conventional and frontier areas for production optimization as well as to disseminate the generated technologies as public good for benefitting the food growers/produces and traders involved in the sector while emphasizing on sustainability, equity and overall food security at household level.
Genesis of AAU -
The embryo of the agricultural research in the state of Assam was formed as early as 1897 with the establishment of the Upper Shillong Experimental Farm (now in Meghalaya) just after about a decade of creation of the agricultural department in 1882. However, the seeds of agricultural research in today’s Assam were sown in the dawn of the twentieth century with the establishment of two Rice Experimental Stations, one at Karimganj in Barak valley in 1913 and the other at Titabor in Brahmaputra valley in 1923. Subsequent to these research stations, a number of research stations were established to conduct research on important crops, more specifically, jute, pulses, oilseeds etc. The Assam Agricultural University was established on April 1, 1969 under The Assam Agricultural University Act, 1968’ with the mandate of imparting farm education, conduct research in agriculture and allied sciences and to effectively disseminate technologies so generated. Before establishment of the University, there were altogether 17 research schemes/projects in the state under the Department of Agriculture. By July 1973, all the research projects and 10 experimental farms were transferred by the Government of Assam to the AAU which already inherited the College of Agriculture and its farm at Barbheta, Jorhat and College of Veterinary Sciences at Khanapara, Guwahati.
Subsequently, College of Community Science at Jorhat (1969), College of Fisheries at Raha (1988), Biswanath College of Agriculture at Biswanath Chariali (1988) and Lakhimpur College of Veterinary Science at Joyhing, North Lakhimpur (1988) were established. Presently, the University has three more colleges under its jurisdiction, viz., Sarat Chandra Singha College of Agriculture, Chapar, College of Horticulture, Nalbari & College of Sericulture, Titabar. Similarly, few more regional research stations at Shillongani, Diphu, Gossaigaon, Lakhimpur; and commodity research stations at Kahikuchi, Buralikson, Tinsukia, Kharua, Burnihat and Mandira were added to generate location and crop specific agricultural production packages.
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ThesisItem Open Access Physicochemical properties of live attenuated duck plague vaccine and evaluation of stabilizer efficacy for lyophilization(College of Veterinary Science, Assam Agricultural University, Khanapara Campus, 2022) Barua, Jonmoni; Das, SutopaDuck plague (DP) or Duck Viral Enteritis (DVE) is an acute contagious herpesvirus infection of ducks and waterfowl of the family Anatidae of the order Anseriformes. Anatid Herpesvirus-1 (AHV-1) or duck enteritis virus (DEV)of the family Herpesviridae is the responsible agent for DP or DVE which is a member. The disease is known to have a global distribution and is associated with significant economic losses worldwide. The only method for preventing and controlling the disease is vaccination. Also, an active decontamination process for an effective vaccination programme in field conditions is important. So, in the present study emphasis has been laid to understand the physicochemical properties of a DPV vaccine strain along with evaluation of thermostability of freeze-dried vaccine with different combinations of stabilizers. In the present study, a vaccine strain of DPV available in the DBT-ADMaCDepartment of Veterinary Microbiology, College of Veterinary Science, AAU, Khanapara was revived in CEF and selected for study on the basis of identity with DPV by observing CPE, PCR and molecular characterization. Characteristic CPE like vacuolation, rounding, syncytium formation and ultimately detachment of cells were observed, in case of PCR band was observed at 1510 bp which proves similar identity with DPV. Molecular characterization revealed homology with DPV isolates from India (Kerala and Assam) and China. Quantitation was done at each step to find out the titre by TCID50/ml after every evaluation right from initial titre, loss of titre during lyophilization, loss of titre during the evaluation of physicochemical treatment, stability evaluation of the freeze-dried vaccine vial, as well as reconstituted vials. The initial titre was found to be 6.9±0.17. The vaccine virus was found to be sensitive to temperatures exceeding 56ºC and above, pH 3 and below, and pH 11 and above. It was also found sensitive to ether and trypsin. On sterility test, no growth was found on the culture. Lyophilization was carried out with 3 combinations of stabilizers namely LS, PTI and LHT. On quality evaluation, PTI and LHT showed uniform cake formation along with minimal loss of titre due to lyophilization. To check the thermostability of freeze-dried vaccines and reconstituted vaccines, vials were exposed at different temperatures. Among the freeze-dried vaccine, LHT could keep the highest titre when exposed to different temperatures and sampled at different time intervals. Although, LS and PTI too could keep with the infectivity titre with minimal loss of titre. In case of the reconstituted vaccine, NSS showed better stability at different temperatures than PBS, though the differences were minimum between the two. Finally, it can be concluded that LHT is one of the better stabilizers for DPV freeze-dried vaccine production. Alternatively, LS and PTI can be used by utilizing a suitable freeze-drying protocol. PBS and NSS both can be used as a diluent for the lyophilized DPV vaccine although in this study NSS was found to be superior. Hence, stabilizer LHT with diluent NSS was found to be superior for the DPV vaccine strain under this study.ThesisItem Open Access Neutralization efficacy of classical swine fever c-strain specific antibody to different genotypes circulating in North Eastern states, India(College of Veterinary Science, Assam Agricultural University, Khanapara Campus, 2022-09) Sarma, Jayashree; Barman, N NClassical swine fever (CSF) or Hog cholera is a highly contagious viral diseases affecting domestic and wild pigs. It has been a big threat to the piggery sector globally, causing negative impact on the economic background. The disease is highly endemic in India including NER. Assam too records highest CSF outbreaks. The recent outbreaks recorded occurrence of genotype 2.2, 2.1 and 1.2 besides wide prevalence of the historical genotypes 1.1. Outbreaks in vaccinated herds and shift in genogroup 1 to 2 globally, has raised the concern over the antigenic variation, protective immune response and neutralizing capacity of C-strain vaccine antibodies. Thus the present study was undertaken to explore the cross- protection efficacy of C-strain vaccine antibodies to the different genotypes or the need for potential vaccine candidate. Tissue samples and lyophilized isolates were selected for the study from CSFV repository, Department of Veterinary Microbiology. Sandwich ELISA and nested RT-PCR was done to determine the presence of the virus. Out of total 49 samples, overall positivity in SELISA was 36.0% (18) and in nested RT-PCR was 30.0% (15). The recovery rate of tissue samples was lower (35.0%) in comparison to lyophilized isolate 40.0%. Molecular characterization of the samples found positive in screening test was done based on E2 full length gene. Five isolates representing each state from north-east was successfully amplified at 1119bp for full length amplification of E2 gene. Genogrouping and phylogentic analysis revealed, genogroups 1.1 and 2.2 circulating in NER showing 98% and 84% nucleotide identity, respectively with the reference Alfort/187 strain. Whereas 99% nucleotide identity within the genogroup. The five isolates with known genogroups were propagated in PK-15 cell line upto 5th passage level and confirmed by S-ELISA and nested RT-PCR. Four isolates were isolated successfully except the isolate from Assam. The OD value at different passage level ranged from 0.589 to 1.763, showing an increase in titre with each subsequent passage. CSFV_AAU_Mg01 showed highest OD value at 5th passage. In-situ demonstration of CSFV by IPT revealed reddish brown cytoplasm indicating replication of the virus in the cytoplasm.TCID50 of the passaged viruses were done by FAT showing comaparble titre (4.49-5.16) with that of vaccine strain at 5th passage level. CSFV_AAU_Mg01 showing highest log TCID50 10 5.16 log TCID50 per ml. Hyperimmune sera was raised using purified cell culture adapted lapinised vaccine showing titres of 1:800 and 1:1600 and used for immunological characterization of the isolates by cross neutralization assay. A 50% neutralization titre of the hyperimmune serum ranged from 1/133 to 1/158 when assayed against the different viruses by FAT. Neutralization and cross – neutralization assay with C-strain specific antibody showed 100% neutralization with genotype 1.1, whereas 84% in geno-type 2.2. The study revealed genotypes 1.1 and 2.2 widely circulating in NER with lower neutralization efficacy of vaccine antibodies to heterologous genotypes.ThesisItem Open Access Seroprevalence and molecular detection of bovine brucellosis and leptospirosis in Assam(College of Veterinary Science, Assam Agricultural University, Khanapara Campus, 2022-09) Devi, Bandana; Saikia, G KBrucellosis and leptospirosis are neglected zoonotic disease prevalent throughout the world. Bovine brucellosis is predominantly caused by Brucella abortus. Leptospirosis in bovine is mainly caused by Leptospira serovars under the serogroup Sejroe. Both the diseases share some common clinical signs and symptoms and cause severe economic losses. The present study was undertaken to estimate the seroprevalence of bovine brucellosis and leptospirosis and diagnose both the diseases by molecular detection of Brucella and Leptospira organisms in clinically suspected and seropositive cases. The study was carried out in Assam during August 2021 to July, 2022. In this study, a total of 1013 cattle serum samples were collected from 11 districts of Assam viz. Tinsukia, Lakhimpur, Dhemaji, Sonitpur, Nagaon, Kamrup-M, Barpeta, Udalguri, Kokrajhar, Dhubri and Cachar, and screened for Brucella antibodyby Rose Bengal Plate Test (RBPT) and Indirect-enzyme Linked Immunosorbent Assay (i-ELISA) to estimate the seroprevalence of the disease. To detect seroprevalence of leptospirosis, a total of 512 cattle serum samples were collected from 7 districts of Assam viz. Dhemaji, Bishwanath, Nagaon, Kamrup-M, Bongaigaon, Kokrajhar and Dhubri, and tested by i-ELISA for Leptospira antibody. A total of 41 serum samples were found to be positive for Brucella antibody by both the tests with a seroprevalence rate of 4.04% and 19 out of 512 serum samples were found to be positive for Leptospira antibody by i-ELISA with a seroprevalence rate of 3.71%. Higher seroprevalence of brucellosis was recorded in female (4.60%) than in male animals (2.16%). Similarly, higher seroprevalence of leptospirosis was recorded in female (4.53%) than in male animals (1.45%). Age wise seroprevalence of brucellosis was found to be highest in animals of 2.1 to 5 years (1st to 3rd lactation) of age(6.32%) followed by animals of 5.1 years and above (4th lactation onwards) age group (2.90%). In case of leptospirosis, animals of 5.1 years and above (4th lactation onwards) age group showed highest seroprevalence (7.47%) followed by animals of 2.1 to 5 years (1st to 3rd lactation) of age (4.14%). In both brucellosis and leptospirosis, higher seroprevalence rate i.e., 6.54% and 4.33%, respectively was recorded in crossbred than in local cattle (1.07% and 2.97%, respectively). In case of brucellosis, animals reared in organised farms showed higher seroprevalence (8.94%) than the animals reared in semi-organised (3.08%) and backyard farms (1.63%). On the other hand, in case of leptospirosis, animals reared in backyard farms showed higher seroprevalence (7.20%) than the animals reared in semi-organised (2.63%) and organised farms (2.47%). In relation to animal health status, the seroprevalence of both the diseases were found to be highest in clinically ill animals with 40.90% for brucellosis and 8.18% for leptospirosis than apparently healthy animals i.e., 3.22% for brucellosis and 3.06% for leptospirosis. Again, among clinically ill animals, seropositivity for brucellosis was highest in animals with history of abortion (66.66%) followed by animals with retention of placenta (50.0%) and repeat breeding (33.33%). Similarly, in case of leptospirosis, highest seroprevalence was found in animals with history of abortion (33.33%) followed by animals with retention of placenta (25.0%) and repeat breeding (13.33%). In this study, both Brucella and Leptospira antibodies could be detected in 5 out of 512 serum samples screened by i-ELISA specific for both the diseases with a seropositivity rate of 0.976%. For molecular detection of brucellosis, 41 seropositive (32 apparently healthy and 9 clinically ill) and 23 clinically suspected (seronegative) samples (whole blood, aborted foetus, placenta, vaginal swab) were tested by Brucella genus specific PCR. Out of these, 9 clinical samples (39.13%) from seronegative cases and 4 samples (9.75%) from seropositive cases were found to be positive for Brucella genomic DNA in Brucella genus specific bcsp31 PCR. Overall, out of 64 samples examined, Brucella genomic DNA could be detected in 13 number of samples with a positivity rate of 20.31%. All 13 Brucella DNA were confirmed as Brucella abortus by multiplex PCR (AMOS). For molecular detection of leptospirosis, 19 seropositive (15 apparently healthy and 4 clinically ill) and 33 clinically suspected (seronegative) samples (whole blood, aborted foetus, placenta, vaginal swab and urine) were tested by Leptospira lipL32 gene PCR. Out of 33 clinically suspected (seronegative) samples, Leptospira DNA could be detected in 6 number of samples with positivity rate of 18.18%. Leptospira DNA could not be detected from seropositive samples. As a whole, out of 52 samples, Leptospira DNA could be detected in 6 sample with an overall positivity rate of 11.53%.ThesisItem Open Access EXPRESSION OF CERTAIN CYTOKINES IN RELATION TO PERSISTENCE OF FOOT AND MOUTH DISEASE VIRUS TYPE ‘O’ IN CATTLE(College of Veterinary Science Assam Agricultural University Khanapara, Guwahati-781022, 2017) Baro, Sangeeta; Sharma., K.The present study was undertaken to detect foot-and-mouth disease virus serotype ‘O’ in oro-pharyngeal fluid (OP fluid) and to quantify cytokines IL-1α, IL- 1β, IFN-α, TNF-α in blood of recovered animal by Real time PCR. Typing of infected clinical samples suspected for FMDV was done by sandwich ELISA followed by simultaneous detection of serotype by multiplex-PCR and detection of antibodies against NSP was done by DIVA ELISA in serum. The Relative Quantification (RQ) values for IL-1α gene during outbreak was 1.383 ±0.405 and after one month of post infection the RQ value was found to be 2.0223 ±0.592 which was found to be upregulated. Subsequently after three month of post infection the expression level of IL-1α was 23.8788±.993 which was upregulated. Later the expression level of IL-1α at 6month and nine month were 1.0223±0.299 and 1.9899±0.565 respectively. IL-1β gene expression was studied and the RQ values was found to be 0.0097±0.002 during one month of post infection which is down regulated and subsequently become undetectable during 3 month and in subsequent period of study period. The expression of IL-1β down regulation was observed in month 1 of post infection, whereas in subsequent period of the study the IL-1β was undetectable. Expression of IFN-α gene during outbreak was 1.0131±0.296. Up egulation of IFN-α in the 15 animals were found during 1, 3, 6 and 9 month respectively. The mRNA expression of TNF- α was studied and found to be upregulated during outbreak and during 1, 3, 6 and 9 month and the level of expression was 1.2361±0.362, 1.6346±0.478, 3.0521±0.893, 2.1447±0.628 and 1.3484±0.394 respectively. The present study thus supports the notion that real-time PCR is a powerful technique for reliable detection of persistent FMDV in recovered animals. The findings also indicated that IL-1α, IFN-α and TNF-α genes were gradually upregulated upto 3 months but IL-1β found to be down regulated with progression of recovery of the animals from the disease. Down regulation of the genes may be due to subside of the acute infection.ThesisItem Open Access IMMUNO PROTECTIVE POTENTIAL OF PARTIALLY PURIFIED TOXOIDS OF Clostridium difficile IN MICE(Assam Agricultural University, Khanapara,Guwahati, 2016-11) HAZARIKA, PARISHMITA; SHARMA, R. K.The present study was undertaken to characterize Clostridium difficile toxins, in respect to the influence of glucose and stages of growth (incubation period) on release of toxins, cytotoxic activities in Vero cells and the immune-protective potential of partially purified toxoids of C. difficile in mice. A total of 10 isolates of C. difficile from the repository of Department of Microbiology, College of Veterinary Science, Khanapara, Guwahati were revived and reconfirmed, based on morphological and staining characteristics, and molecular detection of gluD gene. Characterization of all the 10 isolates, in respect to certain virulence associated genes revealed presence of tcdA (toxin A) and tcdB (toxin B) genes in three strains of C. difficile each. Another three strains could reveal tcdA and tcdB together in the same isolate, while one strain was found to be negative for tcdA and tcdB gene.The protein concentration in the cell free supernatant of toxin A and toxin B positive isolate of C. difficile growth in nutrient media without addition of glucose was found to increase with advancement of growth phases and reached the highest conc. during the decline phase of 48 hr (5.24 µg/µl and 5.06 µg/µl, respectively). Similar trend of protein conc. was observed in the cell free supernatants of both the isolates, in presence of glucose in the nutrient media. However, the presence of glucose was found to suppress the protein conc. in the cell free supernatants of toxin A and toxin B of C. difficile (3.49 µg/µl and 3.99 µg/µl, respectively). The protein profile of toxin A positive C. difficile isolate, in presence of glucose could show 10 protein bands with mol. wt. ranging from 25 to 135 kDa, while the same isolates in absence of glucose in nutrient media revealed 16 protein bands within the range of 22.4 kDa and 100.0 kDa. Similarly, the isolate positive for toxin B revealed 8 protein bands of 35 to 135 kDa range in the cell free supernatant with addition of glucose, while the growth of the same isolate in nutrient media without glucose could exhibit 15 protein bands within the range of mol. wt. 20.0 to 135.0 kDa. Toxin A, B and AB of C. difficile were extracted in thioglycolate media without addition of glucose at 48 hr of incubation and were partially purified by ammonium sulphate precipitation. The partially purified toxins were found to be cytotoxic for Vero cells at two dilution (1:10 and 1:100). Among the three toxins, toxin B was found to be more prominent cytotoxic activities than the other two toxins, A and AB. Complete detoxification was confirmed by testing the monolayer of Vero cells for no cytopathic effect. The immune-protective efficacy of the three toxoid vaccine preparations were tested by immunization of groups of mice with challenge trial on 34th day of post immunization revealed variable protection level. The immunized groups of mice were found to have 100.0 percent protection against homologous challenge dose of 6.0x108CFU. However, the groups of mice, immunized with toxoid A and B could show 75.0 percent protection against challenge with 9.0x108CFU of homologous strains of C. difficile. On the other hand, the vaccine prepared from toxoid AB could confer only 25.0 percent protection in mice, following homologous challenge with 9.0x108CFU. The immunized affected mice, following challenge with 9.0x108CFU dose could show clinical symptoms, suggestive of intestinal disorder, with any mortality. All the affected immunized mice with clinical symptoms were found to recover by the end of the challenge study. The challenge trial with 6.0 x 108 and 9.0x108CFU / dose of homologous strain of C. difficile could produce 100.0 percent mortality in the mice of control group during 48 hr of post challenge observation. The affected mice of the control group revealed an initial development of clinical symptoms, suggesting intestinal infection during 24 hr of observation and all the clinically affected mice were died within 48 hr of challenge. Mortality in mice of control group due to inoculated strain of C. difficile was confirmed by re-isolation of the inoculated strains from the affected liver as well as haemorrhagic part of intestine and intestinal contents.ThesisItem Unknown SERO-SURVEILLANCE AND MOLECULAR CHARACTERIZATION OF INFECTIOUS BURSAL DISEASE FROM POULTRY OF ASSAM(Assam Agricultural University, Khanapara, Guwahati, 2016-01) MEDHI, MANISHA; Das, SutopaInfectious Bursal disease (IBD) is a highly infectious and contagious disease that primarily affects chicks of 3-6 weeks of age causing immunosuppression by affecting the immune system of poultry where it damages the Bursa of Fabricius, thymus etc. The disease has great economic importance in both broiler and pullet growers as the affected birds are susceptible to minor environmental pathogens leading to high morbidity and mortality. The disease is caused by double stranded bisegmented IBD virus (IBDV) that comes under the genus Avibirnavirus of family Birinaviridae. The best way to prevent the disease is by vaccination and good managemental practices. However, there are frequent reports of the occurrence of the disease from different parts of India including Assam. So the present study was aimed to assess the infection by detecting presence of antibodies in the serum samples through indirect Enzyme linked immuno sorbent assay (ELISA) which were randomly collected from unvaccinated local birds from different parts of Assam and detection of virus from clinically affected tissue samples by direct Reverse Transcription- Polymerase Chain Reaction (RT-PCR) and by integrated cell culture PCR (ICC-PCR) after isolating it in the chicken embryo fibroblast (CEF) and Vero cell line. A total of 1093 sera samples were randomly collected from 19 different districts of Assam and screened for presence of antibodies against IBDV using commercial Indirect- ELISA kit. Out of which, 306 samples (27.99%) were found positive. Based on different age groups, collected serum samples were categorized out of which 2-4 weeks of age group meaning young chicks were found to contain antibodies against IBDV. Clinical samples were collected from different places of Assam which shown characteristic necropsy lesion for IBD infection. Total 23 numbers of clinical samples were collected for diagnosis of IBDV antigen through RT-PCR with specific set of primers. Out of which, 12 samples (52.173%) were confirmed for the presence of IBDV. Samples positive in PCR were stained with DNA loading dye and run under polyacrylamide gel electrophoresis along with DNA ladder. A distinct band was observed at 643 bp size region. Representative three PCR amplicon from Nalbari, Hajo and Bijoynagar were further sequenced via an out source and a phylogenetic tree was constructed by maximum likelihood method along with other IBDV isolates reported from various part of the world. Percent identities were analyzed within the isolates reported from our study, from different parts of India and other parts of the world. IBDV can be well adapted in CEF and Vero cells. Virus was passaged for five times in primary chicken embryo fibroblast cells before adaptation in Vero cells. Cytopathic effects (CPE) were observed from second passage onwards in both the cell line. IBDV was passaged in both Vero and CEF cells for at least five times and the cell lysates of each passage were checked by performing Integrated Cell Culture -PCR. All positive samples gave similar results to the pairs of primers which were used for the detection of IBDV nucleic acid in the tissue samples. The present study confirms the prevalence of the disease in poultry population of Assam.ThesisItem Open Access MOLECULAR AND BIOLOGICAL CHARACTERIZATION OF WILD STRAIN OF DUCK PLAGUE VIRUS(Assam Agricultural University, Khanapara, Guwahati, 2016-07) SARMAH, HIRAMONI; DAS, S. K.Duck plague or duck viral enteritis is an acute and contagious viral disease of ducks, geese swan and other waterfowl. The disease is responsible for significant economic losses in duck husbandry due to decrease in egg production, condemnation and mortality in duck. The present study was undertaken to study the molecular and biological characterization of wild strains of duck plague virus. In the present study 6 wild strains of DPV (DP/As-Km/0010, DP/As-Nal/0012, DP/As-Km/0016, DP/As-Km/0019, DP/As-By/0022, DP/As-Km/0025) were revived in ducklings. All the inoculated ducklings developed distinct clinical signs like nasal discharge, lacrimation, pested eyelids, greenish watery diarrhea, soiled vents and sometimes sudden death etc. Post mortem examination revealed gross lesions in brain, oesophagus, liver, spleen, heart, bursa of Fabricious and in intestine. Presence of viral nucleic acid was detected by PCR and detection of duck plague virus antigen in post mortem samples was done with indirect FAT. All the isolates revived in ducklings were further propagated in DEF upto 5th serial passage. The clear CPE was observed from 1st passage onwards. On the basis of DID50 and TCID50, a VV strain of DPV was selected for further study. DID50 of DP/As-Km/0019 was found to be 10-2 and DID50 in case of DP/As-By/0022 and DP/As-Km/0025 was 10-1. Highest TCID50 was found to be 106.33 in case of DP/As-Km/0019. On the basis of these parameters (DID50, TCID50). The strain DP/As-Km/0019 was selected as VV strain of DPV. The pathodynamics of the VV strain was studied by using mean clinical and pathological scores and virus excretion pattern in blood and other clinical samples like tracheal swab and cloacal swab, nasal and ocular swab. Highest mean pathological score was observed in Liver and oesophagus (2.33±0.51) and lowest was observed in thymus and bursa (1.00±0.00).Molecular characterization of selected VV strain of DPV was done by sequencing two genes (UL30, US10) from different region of the virus. Phylogenetic analysis showed close relation with other isolates of DPV and vaccine strain. VNT50 titre of VV strain of DPV (DP/As-Km/0019) was found to be 1:223 which is similar to VNT50 of the vaccine strain and for other moderate virulent strains (DP/As-By/0022 and DP/As-Km/0025), VNT50 was 1:188 and 1:112 respectively. The selected VV strain of duck plague virus was adapted in 9-11 days old embryonated chicken eggs. Different changes like thickening of CAM with extensive haemorrhages, Haemorrhage and congestion throughout the body of infected embryos were observed from 3rd passage onwards. The chicken embryo adapted VV wild strain of DPV was again adapted and propagated in the CEF upto 10th serial passage. The most common CPEs were rounding of cell, vaculation in the cell, syncytia formation and finally detachment of cell monolayer which was observed from 3rd passage onwards.ThesisItem Open Access MOLECULAR CHARACTERISATION OF EXTENDED SPECTRUM BETA LACTAMASE (ESBL) PRODUCING Escherichia coli IN POULTRY(Assam Agricultural University, Khanapara, Guwahati, 2016-07) BASAIAWMOIT, ERNESTINE; Hazarika, A. K.The study was undertaken to isolate and identify Escherichia coli from poultry with or without the history of diarrhoea and to determine the occurrence of extended spectrum beta-lactamase (ESBL) producing Escherichia coli in Assam and Meghalaya, India. A total of 182 (67.40%) samples yielded E. coli which included 106 (67.08%) samples from Assam and 76 (67.85%) samples from Meghalaya. The samples were obtained from cloacal swabs, faecal samples and intestinal contents of diarrhoeic and non-diarrhoeic poultry birds. All the 182 strains of E. coli isolated from diarrhoeic and non-diarrhoeic birds were subjected to antibiotic susceptibility test and were phenotypically confirmed to be ESBL producers by DDST method. A total of 39 (21.42%) samples were confirmed as ESBL producers. Out of these, 19 (17.92%) samples were from Assam and 20 (26.31%) samples were from Meghalaya. Further, the extended-spectrum beta-lactamase genes viz., blaCTX-M, blaTEM, and blaSHV were detected by Polymerase Chain Reaction from the phenotypically confirmed isolates. 17 (9.34%) isolates were found to be positive for at least one of the two resistance genes, viz. blaTEM (686bp) and blaCTX-M (585bp). None of the isolates were found to contain the blaSHV gene. Of the 17 isolates, 5 (2.75%) were found to be positive for blaTEM gene, of which 3 (1.65%) were from Assam and 2 (1.09%) from Meghalaya. Similarly, 12 (6.59%) were found to be positive for blaCTX-M gene, of which 5 (2.75%) were from Assam and 7 (3.85%) were from Meghalaya. Prevalence of the resistant genes in poultry birds was found to be slightly higher in Meghalaya in comparison to Assam.
