Biology subjects

Kaye, K. S.

Publications and source records attributed to Kaye, K. S..

3 recordsLinked to original sources

bioRxiv2025

A Mechanism Based Pharmacokinetic/Pharmacodynamic Analysis of Polymyxin B-Based Combination Therapy Against Carbapenem-Resistant Klebsiella pneumoniae Isolates with Diverse Phenotypic and Genotypic Resistance Mechanisms

Increased resistance to {beta}-lactams/{beta}-lactamase inhibitor by mutations in {beta}-lactamases gene, porin mutations and efflux pumps complicates the management of carbapenem-resistant Klebsiella pneumoniae (CRKP). Polymyxin B (PMB) based combination therapy is considered as a best alternative treatment for those middle and low-income countries that cannot access to the latest medicines. Its crucial to know both phenotypic and genotypic characteristics of a pathogen to understand the killing effect of each drug and its combinations. Hence, our objective of this study was to incorporate mechanistic insights gained from resistance mechanisms to develop a mechanism based pharmacokinetic/pharmacodynamic model (MBM). Six clinical CRKP isolates were used for static concentration time kill (SCTK) assays to evaluate the rate and extent of killing by monotherapy, double and triple combinations using PMB, meropenem and fosfomycin. A MBM was developed using the SCTK data in S-ADAPT. The MBM estimated lower maximum killing rate constant of PMB (3.61 h-{superscript 1}) in an isolate with non-functional MgrB and high-level phenotypic resistance. Based upon model discrimination and PMBs outer membrane disruption, mechanistic synergy was included in 3 isolates which has porin mutations. Mechanistic synergy of PMB was 83-88% with meropenem and 81-98% with fosfomycin. The PMB concentration required to achieve 50% of synergy was 0.48-0.64 mg/L. Simulations with a lower PMB regimen (1mg/kg q12h) and fosfomycin (8g q8h) showed >73% reduction in area under the bacterial load-versus-time curve for four isolates. The triple combination showed 67.7% reduction in non-carbapenamase producing isolate. This study demonstrates that a low dosing regimen of PMB can produce synergistic effects in combination therapy and might be effective in managing infections caused by CRKP, including PMB resistant isolates. Author summaryAntimicrobial resistance is a major concern in treating infectious diseases. CRKP bacterial isolates are resistant to most of the novel antimicrobial agents. One of the primary resistant mechanisms is restricting the permeability of drugs to the site of action. Polymyxin B, an antimicrobial agent, disrupts the bacterial outer membrane, enhancing the permeability of other drugs. When using combination therapy with polymyxin B, selecting drugs with different mechanisms of action is crucial to enhance synergistic effects and improve treatment efficacy. In our study we chose to evaluate the efficacy of meropenem and fosfomycin in double and triple combination therapies. Mechanism based models (MBMs) are the strongest tool to analyse the time course bacterial load data. Our study provides insights into applying available phenotypic and genotypic information to refine and enhance the accuracy of MBMs. Final model simulations revealed that low exposure of polymyxin B below the nephrotoxic threshold was sufficient to produce synergistic effects when combined with fosfomycin and meropenem. Additionally, we found that polymyxin B combination with fosfomycin was more effective compared to meropenem in treating CRKP.

pharmacology and toxicology↗

bioRxiv2021

Measurement of Klebsiella Intestinal Colonization Density to Assess Infection Risk

BackgroundKlebsiella pneumoniae and closely related species K. variicola and K. quasipneumoniae are common causes of healthcare-associated infections, and patients frequently become infected with their intestinal colonizing strain. To assess the association between Klebsiella colonization density and subsequent infections, a case-control study was performed. MethodsA multiplex qPCR assay was developed and validated to quantify Klebsiella (K. pneumoniae, K. variicola, and K. quasipneumoniae combined) relative to total bacterial DNA copies in rectal swabs. Cases of Klebsiella infection were identified based on clinical definitions and having a clinical culture isolate and preceding or co-incident colonization isolate with the same wzi capsular sequence type. Controls were colonized patients without subsequent infection and were matched 2:1 to cases based on age, sex, and rectal swab collection date. Quantitative PCR (qPCR) from rectal swab samples was used to measure the association between relative abundance (RA) of Klebsiella and subsequent infections. ResultsKlebsiella RA by qPCR highly correlated with 16S sequencing ({rho}=0.79; P <.001). The median Klebsiella RA in the study group was 2.6% (interquartile range (IQR) 0.1-22.5, n=238), and was higher in cases (15.7%, IQR 0.93-52.6%, n=83) than controls (1.01%, IQR 0.02-12.8%; n=155; P <0.0001). After adjusting for multiple clinical covariates using inverse probability of treatment weighting, subjects with a Klebsiella RA > 22% had a 2.87-fold (1.64-5.03, P =0.0003) increased odds of infection compared to those with lower colonization density levels. ConclusionsMeasurement of colonization density by qPCR could represent a novel approach to identify hospitalized patients at risk for Klebsiella infection. ImportanceColonization by bacterial pathogens often precedes infection, and offers a window of opportunity to prevent these infections. Klebsiella colonization is significantly and reproducibly associated with subsequent infection, however factors that enhance or mitigate this risk in individual patients are unclear. This study developed an assay to measure the density of Klebsiella colonization, relative to total fecal bacteria, in rectal swabs from hospitalized patients. Applying this assay to 238 colonized patients, high Klebsiella density defined as >22% of total bacteria, was significantly associated with subsequent infection. Based on widely available polymerase chain reaction (PCR) technology, this type of assay could be deployed in clinical laboratories to identify patients at increased risk of Klebsiella infections. As novel therapeutics are developed to eliminate pathogens from the gut microbiome, a rapid Klebsiella colonization density assay could identify patients who would benefit from this type of infection prevention interventions.

microbiology↗

bioRxiv2021

Colistin resistance in Acinetobacter baumannii is driven by multiple genomic traits: Evaluating the role of ISAba1-driven eptA overexpression among Indian isolates

Colistin resistance in Acinetobacter baumannii is mediated by multiple mechanisms. Recently, mutations within pmrAB two component system and overexpression of eptA due to upstream insertion of ISAba1 play a major role.To characterize colistin resistance mechanisms among the clinical isolates of A. baumannii in India. A total of 224 clinical isolates of A. baumannii collected from 2016 to 2019 were included in this study. Mutations within lipid A biosynthesis and pmrAB genes were characterized by Whole Genome Shotgun sequencing. Twenty eight complete genomes were further characterized for insertional inactivation of lpx genes and the association of ISAba1-eptA using hybrid assembly approach. Non-sysnonymous mutations like M12I in pmrA, A138T and A444V in pmrB and E117K in lpxD were identified. Four of the five colistin resistant A.baumannii isolates had insertion of ISAba1 upstream eptA. No mcr genes were identified.Overall, the present study highlights the diversity of colistin resistance mechanisms in A. baumannii. ISAba1-driven eptA overexpression could be responsible for colistin resistance among Indian isolates of colistin resistant A. baumannii.

microbiology↗