The menace of colistin resistance across globe: Obstacles and opportunities in curbing its spread

Genomic investigation unveils high-risk ESBL producing Enterobacteriaceae within a rural environmental water body

Antimicrobial resistance is regarded as a global threat to public health, animals, and the environment, emerging in response to extensive utilization of antimicrobials. The determinants of antimicrobial resistance are transported to susceptible bacterial populations through genetic recombination or through gene transfer, mediated by bacteriophages, plasmids, transposons, and insertion sequences. To determine the penetration of antimicrobial resistance into the bacterial population of the Thiruvandarkoil Lake, a water body located in the rural settings of Puducherry, India, culture-based microbiological and genomic approaches were used. Resistant bacterial isolates obtained from microbiological screening were subjected to whole genome sequencing and the genetic determinants of antimicrobial resistance were identified using in silico genomic tools. Cephalosporin-resistant isolates were found to produce extended spectrum beta lactamases, encoded by blaVEB-6 (in Proteus mirabilis PS01), blaSHV-12 and ompK36 mutation (in Klebsiella quasipneumoniae PS02) and blaSHV-12, blaACT-16, blaCTX-M and blaNDM-1 in (Enterobacter hormaechei PS03). Genes encoding heavy metal resistance, virulence and resistance to detergents were also detected in these resistant isolates. Among ESBL-producing organisms, one mcr-9-positive Enterobacter hormaechei was also identified in this study. To our knowledge, this is the first report of mcr-9 carrying bacterium in the environment in India. This study seeks the immediate attention of policy makers, researchers, government officials and environmental activists in India, to develop surveillance programs to monitor the dissemination of antimicrobial resistance in the environment.

Risk Factors and Outcomes for Isolation with Polymyxin B-Resistant Enterobacterales from 2018-2022: A Case-Control Study

Purpose

To analyze the risk factors and clinical outcomes of patients isolated with polymyxin B-resistant (PR) Enterobacterales from various clinical specimens to prevent and control the spread of these strains.

Methods

This retrospective case-control study included 72 PR Enterobacterales-positive cases and 144 polymyxin B-susceptible (PS) Enterobacterales controls from 2018 to 2022. Patients with PR Enterobacterales isolated in various clinical cultures were defined as cases. Patients with PS Enterobacterales cultures at similar anatomic sites during the same period were randomly selected as controls. Data were collected from clinical and laboratory test records. Bivariable logistic regression and Pearson's chi-square tests were used to assess risk factors.

Results

PR strains were predominantly Klebsiella pneumoniae (72.2%) and Salmonella enteritidis (8.3%). Of the patients, 66.04% were admitted to an intensive care unit (ICU). Risk factors for isolation with PR strains included chronic heart disease (P = 0.012; odds ratio [OR] 1.15; 95% confidence interval [CI] 1.03-1.28), immunosuppressant use (P = 0.016; OR 1.04 [1.0-1.07), drainage tube [head] (P = 0.006; OR 1.1 [1.0-1.1]), and polymyxin B exposure (P = 0.007; OR 1.03 [1.0-1.06]. With respect to outcomes, admission to an ICU (P = 0.003; OR 7.1 [1.9-25.4]), hypertension (P = 0.035; OR 1.4 [1.02-1.83]), and drainage tube [head] (P = 0.044; OR 1.1 [1.0-1.15]) were associated with treatment failure. Additionally, treatment failure was more frequent in patients (45.83%) than in controls (14.58%).

Conclusion

The major risk factors for isolation with PR strains were chronic heart disease, exposure to immunosuppressants, use of drainage tubes, and polymyxin B exposure. The isolation of PR strains in patients was a predictor of unfavorable outcomes. These findings provide a basis for monitoring the spread of PR Enterobacterales.