Altered molecular attributes and antimicrobial resistance patterns of Vibrio cholerae O1 El Tor strains isolated from the cholera endemic regions of India.

AIMS: The present study aimed to document the comparative analysis of differential hypervirulent features of Vibrio cholerae O1 strains isolated during 2018 from cholera endemic regions in Gujarat and Maharashtra (Western India) and West Bengal (Eastern India). METHODS AND RESULTS: A total of 87 V. cholerae O1 clinical strains from Western India and 48 from Eastern India were analysed for a number of biotypic and genotypic features followed by antimicrobial resistance (AMR) profile. A novel polymerase chain reaction was designed to detect a large fragment deletion in the Vibrio seventh pandemic island II (VSP-II) genomic region, which is a significant genetic feature of the V. cholerae strains that have caused Yemen cholera outbreak. All the strains from Western India belong to the Ogawa serotype, polymyxin B-sensitive, hemolytic, had a deletion in VSP-II (VSP-IIC) region and carried Haitian genetic alleles of ctxB, tcpA and rtxA. Conversely, 14.6% (7/48) of the strains from Eastern India belonged to the Inaba serotype, polymyxin B-resistant, nonhemolytic, harboured VSP-II other than VSP-IIC type, classical ctxB, Haitian tcpA and El Tor rtxA alleles. Resistance to tetracycline and chloramphenicol has been observed in strains from both regions. CONCLUSIONS: This study showed hypervirulent, polymyxin B-sensitive epidemic causing strains in India along with the strains with polymyxin B-resistant and nonhemolytic traits that may spread and cause serious disease outcomes in future. SIGNIFICANCE AND IMPACT OF THE STUDY: The outcomes of this study can help to improve the understanding of the hyperpathogenic property of recently circulating pandemic Vibrio cholerae strains in India. Special attention is also needed for the monitoring of AMR surveillance because V. cholerae strains are losing susceptibility to many antibiotics used as a second line of defence in the treatment of cholera.

Regulators of natural competence in Vibrio parahaemolyticus.

Vibrio parahaemolyticus can degrade insoluble chitin with the help of chitinase enzymes that generate soluble N-acetyl glucosamine oligosaccharides (GlcNAcn) to induce a state of natural competence for the uptake of extracellular DNA. In this study, we had evaluated the role of various regulatory factors such as TfoX, CytR, OpaR, and RpoS during natural transformation of V. parahaemolyticus. The results suggest that TfoX regulates natural competence via CytR in a chitin-dependent manner. CytR controls the release of GlcNAc6 from insoluble chitin and conversion of GlcNAc6 into smaller GlcNAc residues inside the periplasm by modulating the expression of endochitinase and periplasmic chitinases. In addition, CytR was also responsible for GlcNAc6-mediated upregulation of competence-related genes such as pilA, pilB, comEA, and qstR. Next, we found that the quorum sensing regulator OpaR affects the natural transformation through its regulation of extracellular nuclease Dns. The ΔopaR mutant showed increased expression of Dns, which might degrade the eDNA. As a consequence, the transformation efficiency was decreased and eDNA-dependent growth was hugely enhanced. However, when Dns-containing DASW was substituted with fresh DASW, the transformation was detectable in ΔopaR mutant and eDNA-dependent growth was less. These results suggest that the occurrence of natural transformation and eDNA-dependent growth were inversely related to each other. Lastly, the general stress regulator RpoS was required for neither quorum-sensing dependent nor chitin-dependent regulation of natural competence in V. parahaemolyticus.

Rapid diagnostic tests versus RT­PCR for Ebola virus infections: a systematic review and meta-analysis

Objective To evaluate the clinical accuracy of rapid diagnostic tests for the detection of Ebola virus. Methods We searched MEDLINE®, Embase® and Web of Science for articles published between 1976 and October 2021 reporting on clinical studies assessing the performance of Ebola virus rapid diagnostic tests compared with reverse transcription polymerase chain reaction (RT­PCR). We assessed study quality using the QUADAS-2 criteria. To estimate the pooled sensitivity and specificity of these rapid diagnostic tests, we used a bivariate random-effects meta-analysis. Findings Our search identified 113 unique studies, of which nine met the inclusion criteria. The studies were conducted in the Democratic Republic of the Congo, Guinea, Liberia and Sierra Leone and they evaluated 12 rapid diagnostic tests. We included eight studies in the meta-analysis. The pooled sensitivity and specificity of the rapid tests were 86% (95% confidence interval, CI: 80­91) and 95% (95% CI: 91­97), respectively. However, pooled sensitivity decreased to 83% (95% CI: 77­88) after removing outliers. Pooled sensitivity increased to 90% (95% CI: 82­94) when analysis was restricted to studies using the RT­PCR from altona Diagnostics as gold standard. Pooled sensitivity increased to 99% (95% CI: 67­100) when the analysis was restricted to studies using whole or capillary blood specimens. Conclusion The included rapid diagnostic tests did not detect all the Ebola virus disease cases. While the sensitivity and specificity of these tests are moderate, they are still valuable tools, especially useful for triage and detecting Ebola virus in remote areas.