Methicillin resistant Staphylococcus aureus (MRSA) is highly divergent antibiotic resistant bacteria earmarked as “High” in global pathogens’ priority list varying the severity and resistance geographically. Here, MRSA were screened using mecA gene with Cefoxitin and other 27 antibiotics of 19 classes using disc diffusion method from a highly humid climate of India. Multiple Antibiotic Resistance (MAR) index was calculated. Minimum Inhibitory Concentration (MIC) was determined against 11 classes of antibiotics. Detection of major virulence genes tst-1 and lukPV were done. A total of 95.24% Hospital Associated (HA)-MRSA, 56.14% Community Associated (CA)-MRSA and 82.53 % Livestock Associated (LA)-MRSA were detected. Cefoxitin, Oxacillin, Ciprofloxacin, Fusidic acid and Ticarcillin-Clavulinic acid resistance was observed in more than 60% of HA-MRSA, CA-MRSA and LA-MRSA. Across the hosts, Mupirocin, Gentamicin, Linezolid, Co-trimoxazole, and Rifampicin were found effective. Vancomycin Intermediate Staphylococcus aureus (VISA) detected in CA-MRSA & LA-MRSA. Multidrug Resistant (MDR) was found very high but extensively drug-resistant (XDR) was detected moderately. No pan drug-resistant (PDR) was detected. Virulence gene tst-1 and lukPV were detected in 7.69% and 32.69% MRSA isolates. The gene tst-1 is reported for the first time in pre and post-caesarian samples from Gynaecology department in this region with high MDR. This study showed S. aureus and subsequent prevalence of MRSA is higher in this region then national data. 2nd generation Cephalosporins were found effective which is very encouraging due to their limited uses. Detection of tst-1 in caesarian samples is a serious threat as neonatal transmission of MRSA from mother is reported.

Salmonella Typhimurium is the most prevalent non-host specific Salmonella serovars and a major concern for both human and animal health systems worldwide contributing to significant economic loss. Type 3 secretion system (T3SS) of Salmonella plays an important role in bacterial adherence and entry into the host epithelial cells. The product of invH gene of Salmonella is an important component of the needle complex of the type 3 secretion system. Hence, the present study was undertaken to clone and express the 15 kDa InvH surface protein of Salmonella Typhimurium in an E. coli host and to evaluate its immune potency in mice. The purified recombinant InvH (r-InvH) protein provoked a significant ( p < 0.01) rise in IgG in the inoculated mice. The immunized mice were completely (100%) protected against the challenge dose of 107.5 LD50, while protection against challenge with the same dose of heterologous serovars was 90%. The bacterin-vaccinated group showed homologous protection of 60% against all three serovars. Findings in this study suggest the potential of the r-InvH protein of S . Typhimurium as an effective vaccine candidate against Salmonella infections.

We investigated the prevalence, antimicrobial susceptibility, antimicrobial resistance and virulence genes of Salmonella isolates recovered from humans and different species of animals. Out of 1231 samples, 88 (7.15%) Salmonella isolates were obtained, among which 21 (23.86%) belonged to Salmonella enterica subsp. enterica sero var. Weltevreden, 22 (25%) to S. Enteritidis, 16 (18.2%) to S. Typhi and 14 (15.9%) to S. Newport; 7 (7.95%) isolates were untypable. Among the 88 isolates, 65.90% showed resistance to gentamicin, 61.36% to tetracycline, 61.18% to cefotaxime, 48.86% to trimethoprim, 45.45% to ampicillin, 11.36% to ceftriaxone, 10.22% to chloramphenicol and 7.95% each to ciprofloxacin and cefepime. Most of the isolates were susceptible, with a low MIC (≤ 0.25 μg/ml) value, to cefepime, cefotaxime, ciprofloxacin, ceftriaxone and co-trimoxazole and with a moderate MIC (0.5–4 μg/ml) to ampicillin, tetracycline, gentamicin and chloramphenicol. The resistance genes blaTEM, tetA and dfrA12 were most prevalent, irrespective of the host of origin of the isolates. While invA was used for molecular detection of Salmonella, other virulence genes, viz. sipA, sipB, sipC, stn and pagN, were also detected in all Salmonella isolates. A total of 38.64% isolates were multidrug-resistant (MDR), and various virulence genes were present among the isolated serovars. This study highlights the importance of continuous monitoring and surveillance for pathogenic Salmonella and their potential risks to both humans and animals.

The study was undertaken to investigate the prevalence, antimicrobial susceptibility, antimicrobial resistance and virulence genes of Salmonella isolates recovered from human and different species of animals and birds. Out of 88 (7.15%), 21 (23.86%) belonged to Salmonella enterica subsp. enterica serovar Weltevreden, 22 (25%) to serovar Enteritidis, 16 (18.2%) to serovar Typhi and 14 (15.9%) to serovar Newport, while 7 (7.95%) isolates were found to be untypable. Among the 88 isolates, 45.45% showed resistance to ampicillin, 61.36% to tetracycline, 61.18% to cefotaxime, 65.90% to gentamicin, 48.86% to trimethoprim, 11.36% to ceftriaxone, 10.22% to chloramphenicol, and 7.95% each to ciprofloxacin and cefepime. Most of the isolates were susceptible to a low MIC (≤ 0.25 µg/ml) of Cefepime, Cefotaxime, Ciprofloxacin, Ceftriaxone and Co-trimoxazole and a moderate MIC (0.5µg/ml − 4µg/ml) of Ampicillin, Tetracycline, Gentamicin and Chloramphenicol. The resistance genes, blaTEM , tetA and dfrA12 were most prevalent, irrespective of the host of origin of the isolates. While invA was used for molecular detection of Salmonella , other virulence genes, viz . sipA , sipB, sipC, stn and T2544 were also detected in all (100%) the Salmonella isolates. Total 69.32 % of tested samples were found to be contaminated with multi-drug resistant (MDR) Salmonella and various virulence genes were present among the isolated serovars. Another virulence-associated gene, T2544 ( pagN ) could also be found in all the isolates, irrespective of serovar or host of origin suggesting the possibility of using this gene as a marker for identification of pathogenic Salmonella isolates. This study highlights the importance of continuous monitoring and surveillance for pathogenic salmonellae and their potential risks to both human and animal.

CURRENT SCIENCE, VOL. 111, NO. 7, 10 OCTOBER 2016 1246 *For correspondence. (e-mail: ggupta@iigs.iigm.res.in) 12. Goswami, D. C., Brahmaputra River, Assam, India: Physiography, basin denudation and channel aggradation. Water Resour. Res., 1985, 21, 959–978. 13. Sarma, J. N., Fluvial process and morphology of the Brahmaputra river in Assam, India. Geomorphology, 2005, 70, 226–256. 14. Lahiri, S. K. and Sinha, R., Morphotectonic evolution of the Majuli Island in the Brahmaputra valley of Assam, India inferred from geomorphic and geophysical analysis. Geomorphology, 2014, 227, 101–111. 15. Lahiri, S. K. and Sinha, R., Tectonic controls on the morphodynamics of the Brahmaputra River system in the upper Assam valley, India. Geomorphology, 2012, 169–170, 74–85. 16. Telford, W. M., Geldart, L. P. and Sheriff, R. E., Applies Geophysics, Cambridge University Press, 1990, 2nd edn.

The virulence of Salmonella depends on virulence factors encoded by specific genes. The present study describes the development of a simple and rapid multiplex PCR (m-PCR) assay for simultaneous detection of seven major virulence genes of Salmonella (invA, invH, stn, sopB, sopE, sefC and pefA). Presence of these genes was studied using 17 standard cultures and 76 field isolates from different sources. Seventeen non-Salmonella strains were also tested for specificity of the optimized PCR. A spiked control experiment was done to detect the sensitivity of m-PCR assay. The primer pairs were found to be specific for Salmonella only. The assay detected 250 pg of purified chromosomal DNA, or 12 cfu of Salmonella in crude lysates. All the field isolates and standard strains of Salmonella were found to carry invA, invH, stn and sopB genes, while variability was observed with respect to sopE, sef C and pefA genes. Thus this multiplex PCR assay provides a simple and rapid method for detection of major virulence factors in important clinical serovars of Salmonella.