Dataset Information

Prevalence of hypermutators among clinical Acinetobacter baumannii isolates.

ABSTRACT: The objectives of this study were to study the presence of mutators in a set of Acinetobacter baumannii isolates and to explore whether there is a correlation between mutation rates and antibiotic resistance.The variation in mutation rate was evaluated for 237 clinical A. baumannii isolates by determining the frequency of their mutation to rifampicin resistance. For each isolate, the antibiotic resistance profile was determined by disc diffusion and/or Etest. Isolates were divided into susceptible, resistant and MDR groups according to their resistance to five groups of different antibiotics. A comparison between differences in mutation frequency (f) and strain-specific factors was performed.Of the 237 isolates 32%, 18% and 50% were classified as susceptible, resistant and MDR, respectively. The f of rifampicin resistance varied between 2.2?×?10(-10) and 1.2?×?10(-6). Of the strains under investigation, 16% had an ?2.5- to 166-fold higher f. The presence of mutators (definition ?2.5-fold increase in f compared with ATCC 19606) in the MDR group (22%) was significantly higher (P?

SUBMITTER: Komp Lindgren P

PROVIDER: S-EPMC4743697 | biostudies-literature | 2016 Mar

REPOSITORIES: biostudies-literature

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Prevalence of hypermutators among clinical Acinetobacter baumannii isolates.

Komp Lindgren Patricia P Higgins Paul G PG Seifert Harald H Cars Otto O

The Journal of antimicrobial chemotherapy 20151209 3

<h4>Objectives</h4>The objectives of this study were to study the presence of mutators in a set of Acinetobacter baumannii isolates and to explore whether there is a correlation between mutation rates and antibiotic resistance.<h4>Methods</h4>The variation in mutation rate was evaluated for 237 clinical A. baumannii isolates by determining the frequency of their mutation to rifampicin resistance. For each isolate, the antibiotic resistance profile was determined by disc diffusion and/or Etest. I ...[more]

PMID: 26660878

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Project description:IntroductionThe development of colistin resistance in Acinetobacter baumannii during treatment has been identified in certain patients, often leading to prolonged or recurrent infections. As colistin, is the last line of therapy for A. baumannii infections that are resistant to almost all other antibiotics, colistin-resistant A. baumannii strains currently represent a significant public health threat, particularly in healthcare settings where there is significant selective pressure.AimThe aim of this study was to comprehensively determine the prevalence of colistin resistance in A. baumannii from clinical samples. Regional differences in these rates were also investigated using subgroup analyses.MethodThe comprehensive search was conducted using "Acinetobacter baumannii", "Colistin resistant" and all relevant keywords. A systematic literature search was performed after searching in PubMed, Embase, Web of Science, and Scopus databases up to April 25, 2023. Statistical analysis was performed using Stata software version 17 and sources of heterogeneity were evaluated using I2. The potential for publication bias was explored using Egger's tests. A total of 30,307 articles were retrieved. After a thorough evaluation, 734 studies were finally eligible for inclusion in the present systematic review and meta-analysis.ResultAccording to the results, the prevalence of resistance to colistin among A. baumannii isolates was 4% (95% CI 3-5%), which has increased significantly from 2% before 2011 to 5% after 2012. South America had the highest resistance rate to this antibiotic. The broth microdilution method had the highest level of resistance, while the agar dilution showed the lowest level.ConclusionsThis meta-analysis found a low prevalence of colistin resistance among A. baumannii isolates responsible for infections worldwide from 2000 to 2023. However, there is a high prevalence of colistin-resistant isolates in certain countries. This implies an urgent public health threat, as colistin is one of the last antibiotics available for the treatment of infections caused by XDR strains of A. baumannii.

Project description:Acinetobacter baumannii is an opportunistic pathogenic bacterium prioritized by WHO and CDC because of its increasing antibiotic resistance. Heterogeneity among strains represents the hallmark of A. baumannii bacteria. We wondered to what extent extensively used strains, so-called reference strains, reflect the dynamic nature and intrinsic heterogeneity of these bacteria. We analyzed multiple phenotypic traits of 43 nonredundant, modern, and multidrug-resistant, extensively drug-resistant, and pandrug-resistant clinical isolates and broadly used strains of A. baumannii. Comparison of these isolates at the genetic and phenotypic levels confirmed a high degree of heterogeneity. Importantly, we observed that a significant portion of modern clinical isolates strongly differs from several historically established strains in the light of colony morphology, cellular density, capsule production, natural transformability, and in vivo virulence. The significant differences between modern clinical isolates of A. baumannii and established strains could hamper the study of A. baumannii, especially concerning its virulence and resistance mechanisms. Hence, we propose a variable collection of modern clinical isolates that are characterized at the genetic and phenotypic levels, covering a wide range of the phenotypic spectrum, with six different macrocolony type groups, from avirulent to hypervirulent phenotypes, and with naturally noncapsulated to hypermucoid strains, with intermediate phenotypes as well. Strain-specific mechanistic observations remain interesting per se, and established "reference" strains have undoubtedly been shown to be very useful to study basic mechanisms of A. baumannii biology. However, any study based on a specific strain of A. baumannii should be compared to modern and clinically relevant isolates. IMPORTANCE Acinetobacter baumannii is a bacterium prioritized by the CDC and WHO because of its increasing antibiotic resistance, leading to treatment failures. The hallmark of this pathogen is the high heterogeneity observed among isolates, due to a very dynamic genome. In this context, we tested if a subset of broadly used isolates, considered "reference" strains, was reflecting the genetic and phenotypic diversity found among currently circulating clinical isolates. We observed that the so-called reference strains do not cover the whole diversity of the modern clinical isolates. While formerly established strains successfully generated a strong base of knowledge in the A. baumannii field and beyond, our study shows that a rational choice of strain, related to a specific biological question, should be taken into consideration. Any data obtained with historically established strains should also be compared to modern and clinically relevant isolates, especially concerning drug screening, resistance, and virulence contexts.

Dataset Information

Prevalence of hypermutators among clinical Acinetobacter baumannii isolates.

Publications

Prevalence of hypermutators among clinical Acinetobacter baumannii isolates.

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