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ThesisItem Open Access STUDIES ON ANTIMICROBIAL RESISTANCE OF Escherichia coli ISOLATES FROM LAMB DIARRHOEA CASES(SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517502. (A.P.) INDIA, 2018-12) SUJATHA, T; Srivani, M(MAJOR); Subramanyam, K.V.; Srinivasa Rao, TA study was carried out on the isolation, molecular characterization, and antimicrobial resistance of E. coli isolates from 1-7, 8-30, 31-60 and 61-90 day-old diarrhoeic lambs from Vizianagaram, West Godavari and Krishna districts of Andhra Pradesh. A total of 212 samples were collected, from which 170(80.18%) E. coli were isolated. Highest prevalence of E. coli was observed in West Godavari (86.41%) and Vizianagaram (82%) districts, while lowest prevalence was found in Krishna district (72.83%). Among different age groups, highest prevalence of E. coli was observed in 1-7 day-old diarrhoeic lambs (84%) while lowest prevalence was detected in 61-90 day-old diarrhoeic lambs (72.72%). Among the E. coli isolates, 87.05% were shiga toxigenic (STEC) and none of the isolates belonged to enterotoxigenic (ETEC). Among the virulence genes of STEC, eaeA &hlyA genes were highest (35.13%) followed by 12.83, 11.48, 10.13, 8.10, 5.4, 4.72 and 2.70% isolates carried stx1; hlyA; stx2;stx2&eaeA; stx1&eaeA; stx2&hlyAand stx1&hlyA and all STEC gens (stx1, stx2, eaeA&hlyA),respectively. Out of 96 hlyA carrying E. coli isolates, only seven isolates did not show any haemolysis on sheep blood agar. Highest antibiotic resistance was observed for the E.coli isolates against colistin (98.82%) and sulphamethizole (89.41%) while enrofloxacin (5.88%), gentamicin (5.33%), and chloramphenicol (1.17%) were effective. Among the STEC isolates, highest antimicrobial resistance (100%) was observed to colistin followed by sulphamethizole (95.94%), while chloramphenicol (1.35%) was effective. An ESBL phenotype was confirmed in a total of 72 STEC isolates. β lactamase genes were detected in 91.21% of STEC isolates with blaTEM being the predominant gene detected (91.21%) followed by blaCTX-M group 1 (77.70%,), blaCTX-M group 2 (10.13%) blaOXA (4.72%,), blaSHV, blaTEM+OXA, and blaCTX-9 (3.37%,), CTX-1+CTX-9 (2.02%) and SHV+OXA (1.35%), respectively. Clove oil was able to inhibit 70% and 50% of multidrug resistant E. coli by well and disc diffusion methods while cinnamic acid did not show any antibacterial activity by both the methods. The present study provides an insight on prevalence of multidrug resistant E. coli against which herbal extracts like clove oil may be effective in treating lamb diarrhoea cases.ThesisItem Open Access STUDIES ON BIOFILM INHIBITION AND ANTIMICROBIAL RESISTANCE IN S. aureus AND STREPTOCOCCUS SPECIES CAUSING BOVINE MASTITIS(SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517502. (A.P.) INDIA, 2018-12) JOSEPH, GREESHMA ANN; RAMANI PUSHPA, R.N.(MAJOR); LAKSHMI KAVITHA, K; SRINIVASA RAO, TBovine mastitis is recognised as the most economically important disease affecting Dairy industry in India and all over the world. Most prevalent bacterial etiological agents identified in bovine mastitis are Staphylococcus aureus, Streptococcus species, E. coli and other Gram-negative organisms. The preferred treatment regime during the past decades for mastitis is antibiotic therapy. The associated antimicrobial resistance and recurrent infections caused by slime producing bacteria is the major constraint. The time has elapsed to think about new treatment methods and agents. Hence the present study is on the biofilm forming S. aureus and Streptococcus species causing bovine mastitis and the effect of antibiofilm agents on the antimicrobial resistance of the microorganisms. A total of 91 Bovine mastitic milk samples were examined and out of this 75 (82.41 %) samples were positive for S. aureus and Streptococcus species. A total of 110 isolates were obtained, the prevalence observed was S. aureus 62 (56.36%), other Staphylococci 2 (1.81%), S. uberis 44 (40%) and other Streptococci 2 (1.81%). All S. aureus and Streptococcus species isolates were confirmed by genus specific PCR followed by species specific PCR. Two Streptococcus isolates did not react to any of the specific primers used for S. uberis, S. agalactiae and S. dysgalactiae. Biofilm formation was detected using qualitative Congo red agar method (CRA), quantitative microtiter plate (MTP) assay and biofilm gene was detected using PCR. On CRA method 88.71% S. aureus isolates and on MTP assay 98.39 % isolates were biofilm producers. The ica locus was detected in 93.54% of the S. aureus isolates. The icaA gene was detected in 87.09% isolates and icaD was detected in 40 isolates. Fifty eight percent were carrying both icaA and icaD genes. On CRA 80.43% Streptococcus species isolates and on MTP assay 84.78% were biofilm producers. Among S. uberis isolates 34.09% were positive for the biofilm gene luxS by PCR. Twenty four isolates without luxS gene also produced very weak or moderate biofilm. On antibiotic sensitivity test the S. aureus isolates were resistant to Penicillin G, Ampicillin, Erythromycin, Methicillin, Clindamycin, Amoxycillin/Clavulanic acid, Streptomycin and were least resistant to Gentamicin, Cotrimoxazole, Chloramphenicol, Tetracycline and Vancomycin. All MRSA isolates were found to be biofilm producers while 96.87 % of MSSA were biofilm producers. MRSA was showing 2 to 4 times more resistance to all tested antibiotics than MSSA. The Streptococcus species showed high resistance to Ceftriaxone followed by Streptomycin, Erythromycin, Penicillin G, Tetracycline, Enrofloxacin, Amoxycillin/Clavulanic acid and least resistance to Gentamicin, Chloramphenicol and Ampicillin/ Sulbactam. Biofilm forming isolates were highly resistant to Ceftriaxone (66.66%), Streptomycin (41.02%), Erythromycin (38.46%), Tetracycline (33.33%) and Penicillin G (30.76%), whereas non biofilm formers showed considerably low resistance to Ceftriaxone (28.57%), Penicillin G (14.28%), Streptomycin (14.28%) and were 100% sensitive to all other antibiotics used. Biofilm inhibition studies were conducted in biofilm producing S. aureus and Streptococcus species identified by MTP. The mean±SE values of inhibition rates by 30 μg /ml Ursolic acid (UA), 100 μg /ml UA, 30 μg /ml resveratrol and 100 μg/ml resveratrol on 26 S. aureus isolates were found to be 40.67±4.64%, 62.03±3.61%, 37.38±4.86% and 53.66±4.25% respectively. Inhibition rates of antibiofilm agents on MSSA were found to be higher than MRSA except for the isolates treated with resveratrol 100 μg /ml concentration. Biofilm inhibition studies were conducted in 31 Streptococcus isolates. The mean±SE values of inhibition rates by 30 μg /ml UA, 100 μg /ml UA, 30 μg /ml resveratrol, 100 μg /ml resveratrol was 33.96±3.17%, 57.40±2.8%, 31.35±3.12% and 46.28±3.47%, respectively. Also, antimicrobial resistance of the isolates treated with antibiofilm agents at concentrations of 100 μg /ml UA and 100 μg /ml resveratrol for 18h was found to be decreased by at least 50% for each antibiotic.ThesisItem Open Access STUDIES ON EXPERIMENTAL SUPPRESSION OF BURSA AND THYMUS DEPENDENT IMMUNE SYSTEM IN DUCKS(SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA, 1992-12) PRASADU, VAKANI; UMAMAHESWARA RAO, S(MAJOR); SUBBA RAO, M.V; SURI BABU, T; SRIRAMAN, P.kThesisItem Open Access MOLECULAR DETECTION AND CHARACTERIZATION OF CLOSTRIDIUM PERFRINGENS TOXIN GENES RESPONSIBLE FOR NECROTIC ENTERITIS IN POULTRY OF ANDHRA PRADESH(SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA, 2008-04) PRAVEEN KUMAR, N; VINOD KUMAR, N(MAJOR); RANI PRAMEELA, D; SUJATHA, KABSTRACT: The present study was carried out to investigate the prevalence of Clostridium perfringens toxin genes responsible for necrotic enteritis in poultry of Andhra Pradesh. A total of 691 faecal samples (396 necrotic enteritis suspected and 295 apparently healthy) comprising of cloacal swabs from live birds and intestinal scrapings from dead birds were collected from different districts of Andhra Pradesh viz., Chittoor, Guntur, Nellore, Krishna, East Godavari and West Godavari. Gross pathological studies of affected birds revealed necrosis of the small intestinal mucosa and submucosa with fibrin deposition resulting in pseudo membrane formation and turkish towel appearance was noticed in the small intestine. Microscopically lumen of intestine with fibrinonecrotic material which forms a visible pseudo membrane composed of cell debris, necrotic/distorted villi, inflammatory cells and clumps of bacteria were observed. The samples were inoculated in to fluid thyoglycollate broth and incubated overnight. DNA extracted from 24 h broth cultures by boiling method were screened by multiplex PCR for simultaneous detection of α, β and β2 toxin genes. Out of 396 (broiler 282 & layer 114) necrotic enteritis suspected samples 337/396 (85.1%) were positive for α toxin gene of which 189/337 (56.08%) were β2 toxin gene positive. Out of 295 (broiler 182 & layer 113) apparently healthy samples 61/295 (20.67%) were positive for α of which 4/61 (6.55%) were β2 positive. None of the sample showed amplification of β toxin gene indicating the absence of C. perfringens type C. As some recent studies focused the involvement of NetB toxin in pathogenesis, therefore, uniplex PCR amplification of NetB gene was done from alpha toxin gene positive samples (C. perfringens type A) yielded no positives for NetB toxin gene. From chi square analysis a significant difference (p<0.01) in the prevalence of toxin genes (cpa & cpb2) between necrotic enteritis suspected and apparently healthy at 99% level of confidence with an increased number of positives from necrotic enteritis suspected group. The present research indicates C. perfringens type A along with β2 toxin gene might be responsible for causing necrotic enteritis in broilers and layers in Andhra Pradesh. The multiple sequence analysis of the amplified partial cpa and cpb2 gene sequences revealed 100% homology between the present isolates, and with selected published sequences from GenBank were found to be 98-99% and 94-99% homology respectively. The phylogenetic analysis of the cpa gene of the present C. perfringens isolate (MG600591) with the selected published sequences of cpa revealed the close segregation in distinct clade with cpa gene of broiler isolate of C. perfringens (GU581186) from Iran. The phylogenetic analysis of three cpb2 sequences of present isolates (MF471364; MF471366; KX001813) segregated into close group of poultry originated sequences with exception of MF471365 which segregated in distinct clade with noporcine originated C. perfringens sequence (AY609173) from USA. Since alpha toxin gene (cpa) is considered as signature toxin gene for C. perfringens, amplification of cpa by PCR is considered as confirmative diagnosis of C. perfringens. Hence, in the present study all the PCR positives for cpa (n=398) were isolated by culturing revealed only 221/398 (55.52%) isolates indicating PCR is more sensitive in detecting C. perfringens when compared with isolation by culturing. In the present study culture supernatant of B. subtilis isolated from healthy intestinal contents of birds successfully inhibited C. perfringens by disk diffusion method indicating its importance as a probiotic in controlling necrotic enteritis in poultry.ThesisItem Open Access IMMUNO INFORMATIC APPROACHES IN DESIGNING VACCINE AGAINST PATHOGENIC LEPTOSPIRA THROUGH PAN GENOME REVERSE VACCINOLOGY(SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA, 2016-12) SUDHEER, P; RANIPRAMEELA, D(MAJOR); VINOD KUMAR, N; JAGADEESH BABU, AABSTRACT: Leptospirosis is a globally important zoonotic disease caused by pathogenic Leptospira and it is a disease of livestock, pet animals, wildlife and humans throughout the world. The losses are due to reproductive problems in livestock and mortality in case of humans. Current existing leptospiral vaccines are unsuccessful due to their limitations .Hence there is a need to develop a novel and efficacious vaccine to control the disease. To overcome this, reverse vaccinology is the right choice. In recent trends, it is possible to target the common vaccine candidates with genomic information of the single organism. Based on this concept the present work was planned to study the Bioinformatics approaches to identify the vaccine candidates in designing a vaccine against pathogenic Leptopsira in Bovines In the present study complete proteomes of L.borgpetersenii hardjo bovis JB 197 and L550 were screened to identify common surface exposed proteins through Rxvi language scripts and codes. Later these common surface exposed proteins were subjected to DEG analysis. 49 essential proteins were identified .Further essential proteins were subjected to non-homology analysis against both host and gut microbiota to avoid autoimmunity using NCBI-BLAST.T-helper cell epitopes were predicted from non-homologous proteins through MetaMHCII and ProPred homology search against BoLA-DRB3, and evaluated using Vaxijen server. Three dimensional structures were built for T-cell epitopes and BoLA-DRB3 using Modeller9v.15. A total of twenty five models were generated. The model with high negative DOPE score was selected and validated using PROCHECK, ProQ, and ProSA in determining protein quality. The structures of T-cell epitopes and BoLA DRB3 were prepared before docking using protein preparation wizard of Schrodinger 2015-3. Docking and free energy calculations were performed with BioLuminate Module v 2.0 of Schrödinger software suite 2015-3. The changes in structural confirmation were monitored in terms of energy plot, RMSD and RMSF during 50 ns MD simulations run time using Desmond v4.3. In Silico analysis of L.borgpetersenii JB 197 and L550 retrieved three proteins namely Ton B dependent receptor containing single epitope, ABC permease protein with three epitopes and UVr ABC protein B with single epitope. L.ballum was selected instead of L.borgpetersenii due to its non-availability of the culture during the period of the study and 99% identity on BLASTp. The nucleotide sequence corresponding to ABC permease gene containing three epitopes was retrieved, primers were designed and PCR was standardized for the amplification of ABC permease gene. PCR purified product on sequencing analysis confirmed the presence of ABC permease gene. Then, the PCR purified product was cloned in to PRSET vector using E.coli DH5α cells .The recombinant plasmid was transformed in to E.coli BL21 (DE3) cells and expression was induced by addition of 1mM IPTG. Finally recombinant protein was extracted from lysate of E.coli BL21 (DE3) cells. Recombinant protein was analysed on SDS-PAGE for characterization. The SDS-PAGE analysis yielded 20KD of expected recombinant protein on staining with commassie brilliant blueThesisItem Open Access STUDIES ON ANTIBIOTIC RESISTANCE AMONG MAJOR BOVINE MASTITIS PATHOGENS IN ANDHRA PRADESH(SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA, 2016-12) USHARANI, K; CHAITANYA, R.K(MAJOR); SREENIVASULU, D; PADMAJA, KABSTRACT: Mastitis remains as a major problem to the dairy industry worldwide, as it affects the quality and quantity of milk production. In the present study a total of 130 milk samples were collected from clinical (101) and subclinical cases (29) of bovine mastitis from different regions of Andhra Pradesh. Isolation of causative bacteria was carried out and a total of 105 bacterial isolates were obtained. The incidence of Staphylococcus spp. (70/105, 66.66%) was found to be high, followed by Enterobacter spp. (16/105, 15.23%), E. coli (11/105, 10.47%) and Streptococcus spp. (8/105, 7.61%). Among the 70 isolates of Staphylococcus spp., 37 were identified as coagulase positive Staphylococci (CPS) and 33 were identified as coagulase negative Staphylococci (CoNS) on tube coagulase test and in coagulase gene PCR. Multiplex PCR carried out for species identification of Staphylococcal and Streptococcal isolates, confirmed all the 37 CPS isolates as S. aureus, a CoNS isolate as S. epidermidis and six isolates of Streptococci as St. agalactiae. The in vitro antibiotic sensitivity test of Staphylococcal isolates revealed high frequency of resistance to pencilin G (48 isolates, 68.57%) followed by cefoxitin (35, 50%), oxacillin (24, 34.28%), gentamicin (6, 8.57%), ciprofloxacin (5, 7.14) and ceftriaxone (2, 2.85%). Interestingly, all the isolates were found susceptible to chloramphenicol. As cefoxitin is used as surrogate for mecA mediated oxacillin / methicillin resistance, 35 (50%) isolates that showed resistance to cefoxitin were phenotypically identified as methicillin resistant, out of which 18 were MRSA and 17 were CoNS. In PCR for mecA and mecC genes that confer methicillin resistance in Staphylococci, only ten (10/70, 14.28%) Staphylococcal isolates were found to carry mecA gene. Three of them were S. aureus and the remaining seven were coagulase negative Staphylococci. The relative frequencies of MRSA and MR-CoNS were 8.1% (3/37) and 21.2% (7/33) respectively. All these mecA positive isolates were found resistant to cefoxitin which is a surrogate for mecA mediated oxacillin/ methicillin resistance. However, six of these mecA positive isolates were found susceptible to oxacillin. None of the 70 Staphylococcal isolates carried mecC gene. Phenotypic resistance was observed in three isolates of St. agalactiae (3/8, 37.5 %), but none was found to carry resistance genes tetO and ermB in PCR. Out of 27 (11 E. coli and 16 Enterobacter spp.) isolates of coliforms, 14 (14/27, 51.85%) isolates were suspected as ESBL producers as they showed resistance to any of the 3rd generation non combination cephalosporins tested in phenotypic screening test. Among these fourteen isolates, only four (4/14, 28.57%) have shown increased diameter of inhibition zones (≥ 5 mm) with the drugs in combination with ß- lactamase inhibitors over the individual drugs and hence these four isolates were phenotypically confirmed as ESBL producers. All the 27 isolates were susceptible to ertapenem and combination drugs of 3rd generation cephalosporins with ß-lactamase inhibitors i.e. ceftriaxone + tazobactem, ceftazidime + clavulanic acid and cefotaxime + clavulanic acid. Out of 27 isolates of coliforms tested for ESBL genes, six isolates (3 E. coli and 3 Enterobacter spp.) were found carry SHV gene in m PCR-I. In m PCR-II, an isolate each of E. coli and Enterobacter spp. were found to carry CTX-M-1 gene and another isolate of E. coli was found to carry both CTX-M-1 and CTX-M-2 gene. Hence these three isolates were confirmed as ESBL producers genotypically. Among the 4 phenotypically confirmed ESBL producers, ESBL genotype was confirmed only in 3 of them (2 E. coli and 1 Enterobacter spp.) with the presence of CTX-M genes. The other ESBL isolate didnot carry any of the ESBL genes. Results of the present study indicate considerably high levels of antibiotic resistance among the major bacterial species causing mastitis in cattle and buffaloes. Hence, it is imperative to go for antibiotic susceptibility testing prior to choosing an appropriate antibiotic for treatment.ThesisItem Open Access PRODUCTION, ISOLATION AND CHARACTERIZATION OF IgY ANTIBODIES TO CANINE PARVOVIRUS(SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA, 2016-12) ATCHUTHARAM, A; SREENIVASULU, D(MAJOR); SREEDEVI, B; ESWARAPRASAD, PABSTRACT: The overall goal of this study was to develop practical, natural, and efficient antimicrobials from egg. The existence of an IgG-like molecule in avian eggs, referred to as IgY, has been well documented, and extensive research has been carried out on its characterization, production and purification. Although it is the functional equivalent of mammalian IgG, the major serum antibody found in mammals, IgY is structurally different, and has been found to exhibit several important differences when compared to mammalian antibodies, including its physico-chemical properties and immunological capabilities. Recently, considerable research has focused on the use of IgY as an alternative to mammalian antibodies in several applications, including immune therapeutic applications, especially for the oral passive immunization against various bacteria and viruses. Much research has also been carried out on the use of IgY as a replacement for IgG in various immunodiagnostic and immune affinity purification purposes. The use of IgY offers several advantages over polyclonal antibodies produced in mammals, including providing a much more hygienic, cost efficient, convenient, humane and plentiful source of antigen-specific antibodies. Chicken immunoglobulin Y (IgY) may provide a new modality in the therapy of various infectious animal diseases. This study presents evidence of its efficacy for canine parvovirus (CPV), which is a highly infectious, fatal viral disease in dogs. Initially IgY antibody production and separation was standardized using BSA as antigen. BSA 0.2 mg/ml was used to immunize three 21weeks old white leghorn chicken. Additional booster doses were administered weekly intervals up to 6 weeks following the first injection. Sera from immunized chicken were collected on 21st day to confirm the immune response to BSA. Among three BSA immunized birds, one birds did not show any response to BSA antigen. Initially BSA specific IgY antibodies were separated from eggs laid by immunized chicken using Ammonium sulphate method. The specificity of IgY antibody raised against BSA was determined by agar gel immunodiffusion test. A clear precipitation line was observed between BSA and anti BSA IgY antibody precipitated from egg yolk, which shows specificity of immune response to BSA. Anti BSA IgY antibody levels were monitored up to 120 days by indirect ELISA and found that the titres were maintained up to 120 days of immunization with the highest titre on 75th day. The present study was conducted as a preliminary step to monitor the in vitro efficacy of IgY as a passive immunotherapeutic agent to control Canine parvovirus infection in dogs. Canine parvovirus vaccine containing 103viral particles/ml was used as antigen to immunize 21 weeks old white Leghorn chicken. The eggs from immunized chicken were collected from 1st day to 135th day. Sera from immunized chicken were also collected on 21st day to confirm the immune response to canine parvovirus. Presence of antibodies against canine parvovirus was checked using hemagglutination inhibition assay (HI). The HI titres of the serum collected from immunized hens was found to be 256 HI units. Water soluble fraction was isolated from eggs collected after the immunization and estimated the protein content and the maximum protein concentration was found (35.20 ± 1.32a mg/ml) in the water soluble fraction collected from egg yolk on 75th day of post immunization. The IgY was separated from the WSF by using Ammonium sulphate method, Sodium chloride method, Sodium sulphate method and PEG method. Among the four methods used for IgY separation, Sodium chloride method and Sodium sulphate methods were found to yield high protein content (6.70 to 6.71mg/ml) compared with Ammonium sulphate method and polyethylene glycol method. IgY was purified using DEAE cellulose column chromatography. Highest protein concentration was observed in the 4th and 5th fractions. The purity of the immunoglobulin present in the 4th and 5th fractions of DEAE cellulose column elute was checked by determining the molecular weight of the protein. A single protein band showing molecular weight 180 KDa was recorded. The titre of the purified canine parvovirus specific IgY antibody was found to be 2048 HI units. Anti canine parvovirus IgY antibody levels were monitored up to 135 days by indirect ELISA. It was found that the titres were be maintained up to 135th day with peak titre (1.186) on day 75th after immunization. Stability of canine parvovirus IgY antibody was studied by exposing to different temperatures and different pH using HI assay. The HI titre gradually decreased when the temperature increased to 50ºC and above. At 25ºC and 37ºC the IgY antibody was found to be stable when exposed to 10, 20 and 30 minutes. Purified IgY antibody when subjected to pH 7 for 8 hours its HI titre was 1024. The HI titre gradually decreased when the pH decreased below 7 and also when pH increased above 7. The stability of purified anti canine parvovirus antibody was completely lost when it is exposed to pH 3 in the presence of pepsin as reflected by complete loss of HI activity. HI titre of the IgY antibody was found to be 32 to 64 when exposed to pH 4.0 and pH 5.0 respectively in the presence of pepsin. The results indicated that the activity of immunoglobulins reduced in the presence of pepsin. Hence, there is a need to protect IgY immunoglobulins against the action of pepsin in the stomach of puppies. Present study was helpful for production of desired IgY antibodies, which can be obtained in large quantities against specific pathogen (canine parvovirus).ThesisItem Open Access STUDIES ON BETA-LACTAMASE ANTIMICROBIAL RESISTANCE IN CANINE MICROBIOTA AND SCREENING OF LACTIC ACID BACTERIA FOR PROBIOTIC ACTION(SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA, 2016-12) NOORBASHA MOHAMMAD SHARIF; SREEDEVI, B(MAJOR); CHAITANYA, R.K; SRILATHA, ChABSTRACT: Microbiota plays a central role in host health and disease. Alterations in gut microbiota can have major consequences, both beneficial and harmful, for host health. In view of this, rectal swab samples from healthy (92) and diarrhoeic (44) dogs as well as pus swabs from pyometra (15) and otitis (15) clinical cases were analyzed. Isolation and identification of canine microbiota was carried out by conventional cultural methods. Gut microbiota isolated include E. coli (65.2% incidence in healthy versus 75% in diarrhoeic dogs), Proteus spp. (61.9% vs. 65.9%), Enterobacter spp. (26% vs. 11.3%), Klebsiella spp. (26% vs. 20.4%) and Pseudomonas spp. (28.2% vs. 45.4%). Microbiota isolated from pus swabs include Staphylococcus spp. (73.3% incidence in pyometra vs. 100% in otitis), Pseudomonas spp. (80% vs. 53.3%), Proteus spp. (0% vs. 60%) and E. coli (46.6% vs. 0%). E. coli isolates were further confirmed by PCR targeting E16S gene and also sent for serotyping based on ‘O’ antigen. Extensive usage of antibiotics in canine practice may lead to development of antimicrobial resistance in dogs. In view of this, all the isolates obtained in the present study were screened for β-lactamase resistance both phenotypically and genotypically. Overall incidence of β-lactamase antimicrobial resistance in phenotypic screening test was found to be 35.8% (125/349), which includes 54 E. coli, 40 Pseudomonas, 22 Klebsiella and 9 Enterobacter species. Of these 125 isolates, resistance to cefotaxime was observed in 80.8%, ceftriaxone in 57.6%, ceftazidime in 52% and aztreonam in 26.4% of isolates. β-lactamase resistance was detected in 34.5 and 42.7% of gut microbiota isolated from healthy and diarrhoeic dogs, respectively; 46.6 and 12.5% of microbiota isolated from pyometra and otitis pus samples, respectively. All the Proteus and Staphylococcus spp. were found to be highly sensitive or intermediately sensitive to β-lactam antibiotics. Overall incidence of ESBL phenotype in phenotypic confirmatory test was found to be 14.6% (51/349), with highest incidence detected in E. coli (31%, 31/100) followed by Klebsiella (21.2%, 7/33) and Pseudomonas (19.6%, 13/66) species. ESBL phenotype was detected in 12.5 and 17.7% of gut microbiota of healthy and diarrhoeic dogs, respectively and 33.3% of microbiota of pyometra pus samples. Detection of β-lactamase genes in canine microbiota was carried out using a set of three multiplex PCR assays and a single uniplex PCR assay. The overall incidence of β- lactamase genes in canine microbiota was found to be 57.3% (200/349). Predominant β- lactamase genes detected in canine microbiota include blaAmpC in E. coli (87%), blaSHV in Klebsiella (84.8%) and Enterobacter (48.2%), blaOXA in Pseudomonas (66.6%) species. Majority of the isolates with confirmed ESBL phenotype carried blaCTX-M G1 gene (72.5%). The blaACC and blaMOX genes were not detected in the canine microbiota. The efficacy of antibiotics against bacterial infections is decreasing with rise in antimicrobial resistance, thus, there is a need to search for novel probiotic strains as potential alternatives to antibiotics. In India, there are no probiotics available for canine usage, as they are host specific. In view of this, rectal swabs (67) from healthy pups were analyzed and a total of 49 (73.1%) Lactobacillus isolates were identified based on morphological, biochemical characteristics and genus specific PCR. Of these 49 isolates, 23 were found to be positive for Group IV; six for Group I, four for Group II and 16 were found to be negative for Lactobacillus group specific PCR. In vitro antibacterial activity of canine Lactobacillus isolates on test pathogens like E. coli, Klebsiella and Enterobacter species have been studied using agar well diffusion assay. Out of 49 Lactobacillus isolates, the supernatants of 20 isolates showed inhibition against majority of the test pathogens examined. The inhibition zones were large and clear against E. coli and Klebsiella spp., but limited and hazy zones were observed against Enterobacter spp. Reduction in antibacterial activity was noticed after neutralization, proteinase K and heat treatment of supernatants, suggesting that the antibacterial activity might be partly due to organic acid production and partly due to heat labile antimicrobial proteins. Nucleotide sequence analysis of genus specific PCR products of 10 selected Lactobacillus isolates that showed consistently high antibacterial activity revealed maximum sequence homology with Lactobacillus fermentum strain RCM 14 (for six isolates), Lactobacillus agilis strain 76CL (for one isolate), Pediococcus acidilactici strain G4 (for 2 isolates) and Weissella confusa strain 3W (for one isolate). In conclusion, the present study revealed alarming β-lactamase resistance in microbiota of dogs in Andhra Pradesh. Therapeutic failures may likely to occur as resistance to commonly prescribed third generation cephalosporins was observed. Lactobacillus strains of dog faecal origin were found to have potent in vitro antimicrobial action. Furthermore, the present study highlighted need for in vivo studies in India to establish probiotic potential of dog faecal Lactobacillus species in the near future.ThesisItem Open Access EPIZOOTIOLOGICAL STUDIES OF INFECTIOUS BRONCHITIS IN CHICKEN IN RAYALASEEMA AREA(SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA, 1979) SUDHAKAR REDDY, A; GOPALA KRISHNA MURTHY, K(MAJOR); KRISHNA SWAMY, S