Prevalence and multidrug resistance in Salmonella enterica Typhimurium: an overview in South East Asia.

Acute/chronic gastroenteritis is caused by a few serovars of Salmonella enterica. Among different serovars, S. enterica Typhimurium is a potent pathogen that contributes significantly to self-limiting diarrhea related mortality worldwide. With no successful vaccine in hand against this pathogen, antibiotics are used as for gold standard for treatment against Salmonella induced gastroenteritis. Indispensably, rise in multi drug resistance against Salmonella Typhimurium poses challenge to treatment options. South East Asia, with 11 different countries, stands 3rd as super region for global burden of Salmonella induced gastroenteritis. In this review, we made an attempt to discuss on prevalence and multidrug resistance in Salmonella Typhimurium in 11 countries of South East Asia-the issue that has not been seriously addressed so far. By thorough analysis of reported data, we found varying frequencies for prevalence of Salmonella Typhimurium as well as subtle evidences on resistance of this pathogen to multiple antibiotics in different countries. Vietnam ranked top in terms of reports for prevalence and antimicrobial resistance. However, in countries such as Brunei and Timor Leste, no study has been performed so far to track the frequency of incidence and drug resistance of this pathogen. Our review, the first of its kind, emphasizes that, although the pathogen was not found as dominant serovar in South East Asia in last 20 years unlike sub-Saharan Africa, it may be still considered as a major threat in this region due to available evidences for infection in humans as well as contamination in several animal and food sources. More importantly, the importance as a public threat in this subregion of Asia is also due to resistance of this pathogen to multiple antibiotics. South East Asian countries showing incidence and multi drug resistance of Salmonella enterica Typhimurium in human and non-human sources (1969-2020). -Drug resistant S. enterica Typhimurium.

Intrinsic insights to antimicrobial effects of Nitrofurantoin to multi drug resistant Salmonella enterica serovar Typhimurium ms202.

Emerging multidrug resistant (MDR) serovar of Salmonella has raised the concern of their impactful effect on pathogenic infection and mortality in human lead by the enteric diseases. In order to combat the battle against these MDR Salmonella pathogen, new drug molecules need to be evaluated for their potent antibacterial application. This study evaluates the mechanistic antimicrobial effect of nitrofurantoin against a MDR strain of Salmonella named S. enterica Typhimurium ms202. The antimicrobial effect of nitrofurantoin was studied through experimental and computational approach using standard microbiological and molecular techniques like growth curve analysis, live-dead analysis, oxidative stress evaluation using high throughput techniques like flow cytometry and fluorescent microscopy. The result showed a potent dose dependent antibacterial effect of nitrofurantoin against S. enterica Typhimurium ms202 with a MIC value of 64 µg/ml. Moreover, the mechanistic excavation of the phenomenon described the mechanism as an effect of molecular interaction of nitrofurantoin molecule with membrane receptor proteins OmpC of S. enterica Typhimurium ms202 leading to internalization of the nitrofurantoin heading towards the occurrence of cellular physiological disturbances through oxidative stress impeded by nitrofurantoin-Sod1 C protein interaction. The results indicated towards a synergistic effect of membrane damage, oxidative stress and genotoxicity for the antibacterial effect of nitrofurantoin against S. enterica Typhimurium ms202. The study described the potent dose-dependent application of nitrofurantoin molecule against MDR strains of Salmonella and guided towards their use in further discovered MDR strains.

Molecular Characterization and Designing of a Novel Multiepitope Vaccine Construct Against Pseudomonas aeruginosa.

ABSTRACT: Pseudomonas aeruginosa, an ESKAPE pathogen causes many fatal clinical diseases in humans across the globe. Despite an increase in clinical instances of Pseudomonas infection, there is currently no effective vaccine or treatment available. The major membrane protein candidate of the P. aeruginosa bacterial cell is known to be a critical component for cellular bacterial susceptibility to antimicrobial peptides and survival inside the host organisms. Therefore, the current computational study aims to examine P. aeruginosa's major membrane protein, OprF, and OprI, in order to design linear B-cell, cytotoxic T-cell, and helper T-cell peptide-based vaccine constructs. Utilizing various immune-informatics tools and databases, a total of two B-cells and twelve T-cells peptides were predicted. The final vaccine design was simulated to generate a high-quality three-dimensional structure, which included epitopes, adjuvant, and linkers. The vaccine was shown to be nonallergenic, antigenic, soluble, and had the best biophysical properties. The vaccine and Toll-like receptor 4 have a strong and stable interaction, according to protein-protein docking and molecular dynamics simulations. Additionally, in silico cloning was employed to see how the developed vaccine expressed in the pET28a (+) vector. Ultimately, an immune simulation was performed to see the vaccine efficacy. In conclusion, the newly developed vaccine appears to be a promising option for a vaccine against P. aeruginosa infection. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10989-021-10356-z.

Genome analysis and virulence gene expression profile of a multi drug resistant Salmonella enterica serovar Typhimurium ms202.

BACKGROUND: In India, multi-drug resistance in Salmonella enterica serovar Typhimurium poses a significant health threat. Indeed, S. Typhimurium has remained unknown for a large portion of its genome associated with various physiological functions including mechanism of drug resistance and virulence. The whole-genome sequence of a Salmonella strain obtained from feces of a patient with gastroenteritis in Odisha, India, was analyzed for understanding the disease association and underlying virulence mechanisms. RESULTS: The de novo assembly yielded 17 contigs and showed 99.9% similarity to S. enterica sub sp enterica strain LT2 and S. enteric subsp salamae strain DSM 9220. S. Typhimurium ms202 strain constitutes six known Salmonella pathogenicity islands and nine different phages. The comparative interpretation of pathogenic islands displayed the genes contained in SPI-1 and SPI-2 to be highly conserved. We identified sit ABCD cluster regulatory cascade in SPI-1. Multiple antimicrobial resistance genes were identified that directly implies antibiotic-resistant phenotype. Notably, seven unique genes were identified as "acquired antibiotic resistance". These data suggest that virulence in S. enterica Typhimurium ms202 is associated with SPI-1 and SPI-2. Further, we found several virulent genes encoding SPI regions belonging to type III secretion systems (T3SS) of bacteria were significantly upregulated in ms202 compared to control LT2. Moreover, all these genes were significantly downregulated in S. enterica Typhimurium ms202 as compared to control LT2 on adding Mn2+ exogenously. CONCLUSIONS: Our study raises a vital concern about the potential diffusion of a novel multi-drug resistant S. enterica Typhimurium ms202. It justifies this clinical pathogen to demonstrate a higher degree survival due to higher expression of virulent genes and enhanced ability of metallic ion acquisition.

Evaluation of Genotypic and Phenotypic Methods for Detection of Methicillin Resistant Staphylococcus aureus in a Tertiary Care Hospital of Eastern Odisha.

INTRODUCTION: Methicillin resistant Staphylococcus aureus has emerged as an important pathogen in nosocomial and community acquired infections. Accurate and rapid identification of MRSA in clinical specimens is essential for timely decision of effective antimicrobial chemotherapy. AIM: The present study was conducted to compare efficacy of four conventional phenotypic methods, with mec- A based polymerase chain reaction (PCR) for MRSA identification. MATERIALS AND METHODS: Methicillin resistance was determined in 200 S.aureus isolates by oxacillin disc diffusion, cefoxitin disc diffusion, Oxacillin Resistance Screening Agar and E-test. The results were compared with mec-A based PCR. RESULTS: Among 200 S.aureus isolates 62 (31%) were positive for mec-A gene by PCR. Cefoxitin disc diffusion, Oxacillin Resistance Screening Agar and E-test showed 100% specificity. Oxacillin disc diffusion had lowest sensitivity (82.5%) and specificity (98.5%) among all. The conventional methods take more time than PCR for diagnosing MRSA. Linezolid, Vancomycin & Dalfopristin were the highly sensitive drugs against MRSA isolates. CONCLUSION: Cefoxitin disc diffusion, is rapid, simple and cheaper, hence can be used routinely as an alternative to PCR for detection of MRSA in resource constraint laboratories.