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Ventilator Associated Pneumonia (VAP) is a nosocomial infection contracted by patients on ventilators, where bacteria colonize the upper digestive tract and contaminated secretions are released into the lower airway. This nosocomial infection increases the morbidity and mortality of the patients as well as the cost of treatment. Of late Probiotic formulations are postulated to prevent the colonization of these pathogenic bacteria. In this prospective observational study, we aimed to investigate the effects of probiotics on gut microbiota and their relation to clinical outcomes in mechanically ventilated patients. For this study, 30 patients were recruited (20 probiotic treated and 10 without probiotic treatment) screened from a cohort of 169 patients. Patients in the probiotic group were given a dose of 6 capsules of commercially available probiotic (VSL#3®:112.5 billion CFU/cap) in three divided doses for 10 days. Sampling was carried out after each dose to monitor the temporal change in the gut microbiota composition. To profile the microbiota, we used a 16S rRNA based targeted metagenomic approach and differences among the groups were computed using multivariate statistical analyses. Differences in gut microbial diversity (Bray Curtis & Jaccard distance, p-value < 0.05) among the probiotic treated group and the control group were observed. Furthermore, treatment with probiotics resulted in the enrichment of Lactobacillus and Streptococcus in the gut microbiota of the probiotic-treated groups. Our results demonstrated that probiotics may lead to favourable alteration in gut microbiome characteristics. Future studies should focus on appropriate dosages and frequency of probiotics, which can lead to improved clinical outcomes.

Increasing occurrence of infections caused by multidrug-resistant Gram-negative bacteria resulted in colistin being the last agent for treatment. Apart from plasmid-mediatedA total of 100 carbapenem-resistantAmong 100 carbapenem-resistantThe performance of cBMD was excellent, whereas the E-test was unacceptable. VITEK-2 and RPNP performed better but remained unreliable due to high error rates. Multiple mutations in the target proteins involving lipopolysaccharide formation, modification, and regulation were seen, resulting in colistin resistance.

Introduction: Increasing occurrence of infections caused by multidrug-resistant Gram-negative bacteria resulted in colistin being the last agent for treatment. Apart from plasmid-mediated mcr genes, mutations involving several genes like mgrB, phoP/phoQ, pmrA, pmrB, pmrC, and crrABC genes, are leading causes of colistin resistance. Four colistin susceptibility testing methods were compared against broth microdilution (BMD) and determined the presence of the mcr1-5 gene. Methodology: A total of 100 carbapenem-resistant Enterobacterales isolates were tested for colistin susceptibility by commercial broth microdilution (cBMD), E-test, VITEK-2, and rapid polymyxin NP assay (RPNP) and compared with BMD. The presence of the mcr1-5 gene was determined by modified RPNP and PCR. Two non- mcr colistin-resistant XDR isolates were subjected to whole-genome sequencing using Illumina MiSeq sequencing platform. Results: Among 100 carbapenem-resistant Enterobacterales isolates, 15% were resistant to colistin. Essential agreement, categorical agreement, major error, and very major error for cBMD/E-test/VITEK-2/RPNP were 96%/73%/82%/NA; 99%/86%/88%/91%, 1.2%/9.4%/11.8%/8.2% and 0%/40%/13.3%/13.3%, respectively. Only one Klebsiella pneumoniae isolate harbored the mcr-1 gene, observed by both methods. Whole-genome sequencing of two non- mcr XDR Klebsiella pneumoniae showed multiple mutations in 10 genes responsible for lipopolysaccharide biosynthesis. Conclusions: The performance of cBMD was excellent, whereas the E-test was unacceptable. VITEK-2 and RPNP performed better but remained unreliable due to high error rates. Multiple mutations in the target proteins involving lipopolysaccharide formation, modification, and regulation were seen, resulting in colistin resistance.