National Institute of Cholera and Enteric Diseases,Indian Council of Medical Research

The present study investigates the effect of the degree of carboxymethyl substitution in tara gum (TG) on the physicochemical and mucoadhesive properties of gastroretentive tablets. The synthesis of carboxymethyl TG (CMTG) was optimized under various reaction conditions with respect to degree of substitution (DS). The DS varied from 0.47 ± 0.002 to 1.14 ± 0.014 depending on the reaction conditions. The DS significantly influenced the flow properties, swelling behavior, and erosion of the tablets. Ex vivo mucoadhesion studies on goat stomach mucosa revealed that both mucoadhesive strength (MS) and mucoadhesive time (MT) varied with changes in DS. MS and MT progressively increased from 45.51 × 103 ± 2.979 to 111.18 × 103 ± 3.901 dynes/cm2 and from 272.66 ± 2.561 to 517.33 ± 2.516 min, respectively, with increasing DS from 0.47 ± 0.002 to 1.05 ± 0.046, owing to enhanced hydrogen bonding between the -COOH groups of CMTG and functional groups of mucin. However, a further increase in DS to 1.14 ± 0.014 decreased MS and MT to 101.75 × 103 ± 0.297 dynes/cm2 and 504.33 ± 1.041 min, respectively, primarily due to excessive protonation in acidic media, which increased the rigidity of the polymeric networks and reduced interactions between polymeric chains and mucin. The most notable finding of this study was that the MS and MT values of the optimized carboxymethylated derivative (CMTG-4) were superior to those of the commercial mucoadhesives CMC, Carbopol 934, and pectin.

IntroductionDiarrhea is a leading contributor of mortality globally. To mitigate its disease burden, improved prognosis and alternative therapeutic approaches must be deployed. A cross-sectional gut microbiome analysis of 23 non-diarrheal and 5 diarrheal fecal samples was conducted with the aim of meeting the WHO’s GAPPD (Global Action Plan for Pneumonia and Diarrhea) goals.HypothesisNext-generation sequencing is a potent tool being increasingly used for epidemiological surveillance. It can help in the comparison of the structural diversity of the gut microbiome between diarrheal and non-diarrheal samples, thereby aiding in the identification of prospective prognostic and therapeutic candidates.AimThe pilot study was designed to identify prospective taxa that were comparatively enriched in non-diarrheal samples and to predict gut microbial community interactions.Methodology16S rRNA amplicon sequencing and subsequent analysis were undertaken for taxonomic profiling and abundance interpretation of OTUs.ResultsSignificant differences between the two groups with respect to structural composition was revealed. Firmicutes was the most abundant phylum in the majority of the samples. The B/F ratio was consistently <1 in all diarrheal samples. A significant difference in the mean B/F ratio of the two groups was found. Proteobacteria was significantly more abundant in the diarrheal group. On the other hand, Prevotellaceae was the most abundant family in non-diarrheal samples and was suppressed significantly in diarrheal samples. Streptococcaceae was the most abundant family in 60% of diarrheal samples; where Streptococcaceae was suppressed, Bacteroideaceae and Nocardiaceae were the most abundant. In non-diarrheal samples, where Streptococcaceae was almost completely suppressed, Bifidobacteriaceae was the most abundant and significantly suppressed other families. A negative correlation was observed between Prevotellaceae and Bacteroideaceae in the non-diarrheal group. Prevotella copri was the most abundant species in 70% of non-diarrheal samples and was significantly suppressed in diarrheal samples. Proteus mirabilis was identified in all the non-diarrheal samples, while they were absent in diarrheal samples.ConclusionThe OTUs associated with diarrheal dysbiosis can serve as prognostic markers. To our knowledge, this is the first report on the comparative analysis of diarrheal and non-diarrheal microbiome, distinctly addressing the gut microbiome dysbiosis from the context that can lead to the development of prognostic markers and probiotics to protect the endemic population from diarrhea and help in achieving Sustainable Development Goals 2 and 3.

Background Klebsiella pneumoniae , a WHO-designated critical-priority pathogen, predominate neonatal bacteraemia in India manifesting high morbidity and mortality. Global emergence and trafficking of high-risk clones signal therapeutic crisis amid virulence-resistance convergence. This study presents antimicrobial resistance and virulence traits of K. pneumoniae ST709-KL9 strain recovered from neonatal blood in West Bengal, India. Methods and Results The blood isolate from a 10-day-old neonate (November 2021) underwent identification, antimicrobial susceptibility testing, hypermucoviscocity assessment, and whole genome sequence analysis. The 5.47 Mb genome comprised of one chromosome (5.2Mb) and three plasmids [conjugative IncFIIK (59.4kb), IncHI1B:IncFIB pNDM-MAR-like (219.7kb), IncR (13.2kb)]. Core findings included ST709 (single-locus variant of ST15), KL9/O2 capsular type, and multidrug-resistant phenotype (third-generation cephalosporin/fluoroquinolone/chloramphenicol/co-trimoxazole/fosfomycin/tigecycline resistant) The strain was treatable with carbapenems, aminoglycosides, and colistin. Resistome featured chromosomal point mutations ( gyrA : Ser83Tyr/Asp87Ala, parC :Ser80Ile, uhpT: Glu350Gln, EF-Tu: Arg234Phe, ompK37 : Ile70Met/Ile128Met; IncR plasmid-borne bla TEM−1B / bla CTX−M−15 /qnrS1 ; IncHI1B:IncFIB aph(3″)-Ib/aph (6) -Id/catA1/sul1/sul2/tet(D . Virulome revealed Type I/III fimbriae, complete T6SS-I cluster, KL9 capsule biosynthesis, enterobactin/salmochelin iron acquisition—lacking canonical hvKp markers (string-test negative). Conclusions This is the first report of K. pneumoniae ST709-KL9 (descendent of ST15) strain carrying outbreak-prone antibiotic resistance genes and posing an imminent public health threat to Indian healthcare fraternities. Systematic and strategic large-scale genomic AMR surveillance is essential to understand the trafficking, contain the transmission, and terminate the chain-of-infection of superbugs in India.

Biofilm formation, extracellular substance synthesis, and virulence factor production all have a major impact on drug tolerance and infection propagation caused by Staphylococcus aureus. Flavonoid compounds have been explored as potential solutions to enhance antibiotic efficacy against the biofilm formation of pathogenic microbes. Quercetin (QER) has previously demonstrated antibacterial and antibiofilm properties. This study examines the potential of QER on enhancing the antibacterial, antibiofilm, and antivirulent potential of conventional antibiotics gentamicin (GEN), and ciprofloxacin (CIP) and aims to decipher the underlying mechanisms of action.Our research demonstrates that combining QER with GEN or CIP enhances their antibacterial activity, disrupts S. aureus cell membrane integrity, and increases reactive oxygen species production, leading to enhanced bacterial cell lysis. Furthermore, the combinatorial effect of QER with sub-MIC of GEN and CIP markedly inhibits biofilm formation, reduces viable cell counts, and diminishes the extracellular matrix components. The inhibition of biofilm after combinatorial treatment is confirmed through fluorescence microscopy and scanning electron microscopy. The study also found that QER-antibiotics combinations strongly reduce virulence characteristics in S. aureus, (spreading ability, protease, and hemolysin production) controlled by global key regulatory factors AgrA and SarA.Gene expression analysis revealed down regulation of key regulatory genes (sarA and agrA) and the virulence gene (hla).Molecular docking experiments have revealed the interaction between QER and the quorum sensing regulatory proteins SarA and AgrA, predicting another possible mechanism by which QER improves the anti-biofilm and antivirulence efficacy of GEN and CIP. Collectively, our findings indicate that QER enhances the efficacy of GEN and CIP antibiotics in reducing the antibiofilm and virulent characteristics of S. aureus, highlighting its potential as a broad-spectrum strategy for controlling S. aureus pathogenicity.

BACKGROUND:Patients with cholera have been shown to be protected against subsequent cholera for 3 years after their initial episode. We aimed to assess protection at 10 years of follow-up. METHODS:In this retrospective cohort study, cohorts of patients treated for cholera (index patients) and contemporaneously selected age-matched individuals without cholera (controls), randomly selected from the population of Matlab, Bangladesh, were assembled between 1990 and 2009 and followed for up to 10 years. Selection of participants who had no history of cholera in the 5 years before selection proceeded in secular sequence, and selection was done without replacement. Protection against subsequent treated cholera was assessed in proportional hazards models and waning of protection was assessed non-parametrically with use of smoothing of protection curves. FINDINGS:We included 3925 index patients and 23 550 matched controls. Patients with El Tor cholera (26 subsequent episodes among 3619 index patients) had a 48·6% (95% CI 23·1 to 65·7; p=0·0012) lower risk of El Tor cholera than controls, with no evidence of waning during up to 10 years of follow-up (p=0·87). Index patients aged 5 years and older with El Tor cholera (nine subsequent episodes among 2279 index patients) were at a 61·7% (23·6 to 80·8; p=0·0065) lower risk of El Tor cholera, whereas index patients younger than 5 years with El Tor cholera (17 subsequent episodes among 1340 index patients) had a 36·2% (-5·0 to 61·3; p=0·077) lower risk (p=0·26 for the difference by age). INTERPRETATION:Protection against El Tor cholera associated with previous El Tor cholera was moderate in magnitude and sustained over 10 years of follow-up. These findings suggest the potential for sustained, long-term protection by oral cholera vaccines in populations with endemic cholera and help inform models of cholera in endemic settings. FUNDING:Bill & Melinda Gates Foundation.