Antimicrobial resistance (AMR) in poultry production chain is one of the major food safety concerns due to indiscriminate usage of antibiotics and the presence of pathogens such as Salmonella which causes infections in various stages of production. In the present study, 182 samples were collected from commercial broiler supply chain, viz., three hatcheries ( n = 29 ), three commercial broiler farms (CBF; n = 99 ), and three retail meat shops (RMS; n = 54 ), and used for isolation and identification of Salmonella using three different selective agar media and a selective enrichment medium followed by PCR confirmation targeting the hilA gene. The overall prevalence of Salmonella was 47/182 (25.82%), and a significantly higher ( P < 0.05 ) prevalence was observed in retail meat shops (46.29%), CBF (19.19%), and hatcheries (10.34%). Comparison of three agar media for isolation of Salmonella revealed that all the media were equally selective. However, PCR amplification of hilA gene fragment was significantly higher ( P < 0.01 ) in selective enrichment culture tetrathionate brilliant green bile broth (TTB) as compared to all solid (agar-based) media. Susceptibility pattern against most frequently used antibiotics revealed that 100% of the isolates were resistant to at least one antibiotic. High resistance was observed for doxycycline (94.34%), followed by cefpodoxime (84.91%), ciprofloxacin (72.64%), gentamicin (65.09%), enrofloxacin (61.32%), colistin sulphate (40.42%), amikacin (34.91%), ampicillin (33.96%), neomycin (33.02), cefotaxime (30.19%), ceftazidime (29.25%), trimethoprim-sulfamethoxazole (23.58%), amoxicillin+clavulanic acid (21.70%), and chloramphenicol (12.26%); 16.98% of the isolates were ex-tended spectrum β-lactamase (ESBL) producers, and 76.41% were multidrug resistant (MDR). MDR Salmonella were significantly higher ( P < 0.01 ) in RMS (91.66%) followed by CBF (82.75%), whereas no MDR isolates were present in the isolates from hatcheries. The results indicated a higher prevalence of Salmonella and AMR for commonly used antibiotics in the complete broiler supply chain, especially RMS and CBF. Also, this study idicated that TTB enrichment followed by PCR and colony PCR was found to be rapid, specific and time-saving method.

In the present study, 15 S. agalactiae out of 56 streptococcal isolates recovered from 98 milk samples collected from clinical cases, one organized farm and two unorganized sectors in and around Bangalore. All the streptococcal isolates were confirmed at genus level using genus specific primers targeting tuf gene of Streptococcus. Species level identification for S. agalactiae, S. dysgalactiae and S. uberis was done using 16S rRNA. Primers were designed for targeting cfb gene of S. agalactiae, mig gene of S. dysgalactiae, whereas for targeting sip, hyl gene of S. agalactiae and skc, pauA gene of S. uberis either published or designed earlier were used to screen for virulence genes of streptococcal isolates and reference strains. Desired amplicons for the virulence genes were obtained. All the S. agalactiae isolates were also screened for CAMP factor phenotypically by employing CAMP test which was demonstrable in fourteen isolates but cfb gene encoding for CAMP factor was detectable by PCR in all the isolates. The study ultimately helps us to understand the virulence characteristics and mechanisms behind emergence of new strains or shifts in mastitis epidemiology in response to control measures, including antibiotic treatment and vaccination.

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The study was conducted to determine the effect of subclinical mastitis (SCM) and clinical mastitis (CM) on haemato-biochemical parameters and milk leukocyte count of crossbred cattle. Milk and blood samples were collected from 20 healthy, 223 SCM and 47 CM affected animals from Kolar and Chikkaballapur districts of Karnataka state, India. The SCM were diagnosed by California Mastitis Test (CMT) and electrical conductivity (EC) of milk. Blood and milk of mastitis infected crossbred cattle were analyzed for haemato-biochemical parameters and milk leukocyte count. Haematology showed significant increase in TLC in crossbred cows affected with mastitis. Significantly (P< 0.05) lower average values of TEC, Hb and PCV were observed in SCM infected animals, however no significant change were observed in values of CM infected than healthy animals. Differential leucocytic count (DLC) revealed higher granulocytes and lymphopenia in mastitis infected animals. Biochemical estimation revealed significantly (P< 0.05) higher average values of Ca, P, Na, Cl, and K in mastitis infected compared with healthy animals however, no significant (P> 0.05) change was observed in Mg and ALT levels. AST and TP values were significantly increased in SCM infected compared to healthy animals however, no significant change were observed in CM infected animals.

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