Peer Reviewed Journal Articles (Inter.) (M,F&B)
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- ItemFood grade zinc oxide bulk particle composite can replace the toxic zinc oxide nano composite towards the control of pathogenic and spoilage bacteria(Oxford Academic, 2020-12-15)ZnO-Nanoparticle-Chitosan (ZnO-NP-CH) composite has potential biomedical and food applications due to its better antimicrobial activity. However, the presence of nano-metal-oxide in the composite makes the material unsuitable for any food applications. Moreover, the cost involved in the preparation of Zinc Oxide-Nano-Particle (ZnO-NP) is a major limitation for commercial food applications. Hence a suitable alternative for ZnO-NP is highly needed for food application. Since ZnO-Bulk Particles (ZnO-BP) are food grade and there is no study on the composite prepared from ZnO-Bulk Particle-Chitosan (ZnO-BP-CH), in the present study, antimicrobial activity was assessed for ZnO-BP-CH and compared with ZnO-NP-CH. Based on the study, it was observed that in the individual form of ZnO-NP possessed significantly higher antimicrobial activity than ZnO-BP. The composite form of ZnO-NP-CH and ZnO-BP-CH possessed higher antimicrobial activity than chitosan. However, no significant difference was observed between the composite forms. Hence, ZnO-BP-CH could be recommended as a suitable alternative to ZnO-NP-CH for future studies related to chitosan with ZnO composite to avoid costly nanomaterials preparation.
- ItemFish-borne methicillin resistant Staphylococcus haemolyticus carrying atypical staphylococcal cassette chromosome mec (SCCmec) elements(Elsevier, 2021-03)Prevalence of staphylococci in fish and fish products pose high risk of foodborne diseases. As far as Staphylococcus haemolyticus as a reservoir of methicillin resistance is considered, main objective of the present study was to surveil the incidence of methicillin-resistant Staphylococcus haemolyticus (MRSH) in fishes and its genotypic characterization. 79 fish samples were collected from retail markets in three pre-decided sites in Assam. The collected fish samples were subjected to microbial analysis and as result 13 MRSH could be isolated. Susceptibility of the isolates towards various classes of antibiotics was assessed by employing BD Phoenix M50 system. Polymerase chain reaction (PCR) was performed for the molecular detection of methicillin-resistance determinant. Molecular typing of the isolates was attempted by recruiting staphylococcal cassette chromosome mec (SCCmec) and pulsed-field gel electrophoresis (PFGE). Out of 79 fish samples collected from retail markets in Assam, 13 tested positive for MRSH. These isolates showed varying levels of resistance to different classes of antibiotics such as cephalosporin (100%), lincosamide (30.76%), macrolides (30.76%), aminoglycoside (53.85%), quinolones (38.46%) and sulfonamides (61.54%). BD Phoenix M50 instrument recognized a few isolates as inducible macrolide-lincosamide-streptogramin B (iMLSb) phenotype (30.76%). Remarkably, all the isolates were reported as multi-drug resistant (MDR) as they showed resistant to ≥3 classes of antibiotics. All the studied isolates were positive for mecA gene and carrying multiple SCCmec elements. PFGE cluster analysis grouped the isolates into two major clusters and seven individual lineages. In short, the current study documented the incidence of multi-drug resistant, multiple SCCmec elements carrying S. haemolyticus in fishes. Considering the fact that S. haemolyticus contributes greatly in the dissemination of methicillin resistance owing to their extreme genome plasticity, the present study admonition the necessity of continuous monitoring the S. haemolyticus contamination in food. The study also discussed role of prudent hygienic practices in flattening the AMR curves.
- ItemPrevalence of virulent and biofilm forming ST88-IV-t2526 methicillin-resistant Staphylococcus aureus clones circulating in local retail fish markets in Assam, India(Elsevier, 2021-09)The burden of antimicrobial resistance (AMR), particularly in India has been increased alarmingly. Methicillinresistance in Staphylococcus aureus has been recognized as serious threat to the human especially if they are biofilm forming and equipped with virulence factors. In the present study monitoring of antibiotic resistant S. aureus was performed at three selected sites in Assam, India in August 2019 and February 2020. Ethnographic information was collected from the fish vendors in order to track and address potential sources of contamination. Twenty three potential methicillin-resistant S. aureus (MRSA) isolates were identified from the fish sold by the vendors and subjected to molecular characterization. The antimicrobial resistance profile of these MRSA isolates were regarded as multidrug-resistant (MDR) as they were resistant to ≥3 classes of antibiotics. The most prevalent resistance profile was; ampicillin-cefazolin-cefoxitin-gentamicin-norfloxacin-oxacillin-penicillin. Accessory gene regulators III (agr III) type MRSA (18/23, 78.26%) were found to be predominant compared to agr I type (5/ 23, 21.74%). Four isolates (17.39%) were observed to carry SCCmec-IV elements, which is a typical feature of community-associated MRSA (CA-MRSA). Two SCCmec-IV MRSA isolates were found to harbour pantonvalentine- leucocidin (PVL) toxin genes and were resistant to macrolide in addition to beta-lactams. MLST and spa typing identified all MRSA as ST88 with spa type t2526. This is the first report from India on the incidence of ST88-SCCmec-IV (ST88-IV) MRSA in a fish market and its aquatic environs. The high prevalence of a single MLST clone, ST88, suggests that this lineage has a unique survival advantage in this environment. The study discusses the contribution of hospital wastewater in the dissemination of pathogenic MRSA clones to aquatic resources and then to humans through the food chain.
- ItemQuorum quenching Bacillus spp.: an alternative biocontrol agent for Vibrio harveyi infection in aquaculture(Inter-Research Science Publisher, 2021-10-07)Quorum sensing (QS) is a type of cell to cell communication in bacteria that can also regulate the virulence potential in pathogenic strains. Hence, QS disruption, i.e. the quorum quenching (QQ) mechanism, is presently being explored as a novel bio-control strategy to counter bacterial infections. In the present study, we characterized the QQ ability of Bacillus spp. strains to reduce the expression of some virulence factors of a shrimp pathogen, Vibrio harveyi. We screened a total of 118 spore-forming bacterial isolates from aquaculture ponds and mangrove soil for their ability to degrade the synthetic N-acyl-homoserine lactones (AHLs) C4-HSL, C6-HSL, C8-HSL, and C10-HSL. We then selected the top 17 isolates with high AHL-degradation ability for further study. Among them, B. subtilis MFB10, B. lentus MFB2, and B. firmus MFB7 had the highest ability for degradation. These 3 isolates suppressed the expression of virulence genes encoding protease, lipase, phospholipase, caseinase, chitinase, and gelatinase, and potentially inhibited the biofilm formation of V. harveyi MFB32. The reduction in expression of virulence genes like those coding for metalloprotease, serine protease, and haemolysin were confirmed by real-time PCR analysis. Moreover, in an in vivo challenge experiment, these Bacillus spp. protected Penaeus monodon post-larvae against V. harveyi MFB3 infection. Our results demonstrate the potential application of AHL-degrading Bacillus spp. as an alternative to antibiotics in shrimp hatcheries to control luminescent vibriosis. This novel bio-therapeutic method is a promising approach towards disease control in shrimp aquaculture.
- ItemAntimicrobial resistance in Vibrios of shrimp aquaculture: Incidence, identification schemes, drivers and mitigation measures(Springer, 2021-01-18)Antimicrobial resistance (AMR) is a growing threat to the human, and animal population, worldwide. The antimicrobials used across all the sectors eventually pollute the aquatic environment and transform it into a hot spot for the emergence and spread of AMR. The bacteria under the genera Vibrio being ubiquitous to aquatic environment include a few species which are pathogenic to humans and aquatic animals. Despite extensive reviews available on AMR in human, terrestrial animal sectors and environment, there is a dearth of summarized information on AMR in Vibrios in shrimp aquaculture environment. In comparison to the human, and terrestrial animal health sector, a methodology for determination of AMR in vibrios associated with aquatic animals is still in its nascent stages and needs harmonization. The present review is centred on the AMR status in vibrios of shrimp farming environment and recent advances in the detection of resistance and discusses methodologies for AMR determination in vibrios and possible mitigation measures to control AMR spread.