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Evolutionary action of mutations reveals antimicrobial resistance genes in Escherichia coli.

ABSTRACT: Since antibiotic development lags, we search for potential drug targets through directed evolution experiments. A challenge is that many resistance genes hide in a noisy mutational background as mutator clones emerge in the adaptive population. Here, to overcome this noise, we quantify the impact of mutations through evolutionary action (EA). After sequencing ciprofloxacin or colistin resistance strains grown under different mutational regimes, we find that an elevated sum of the evolutionary action of mutations in a gene identifies known resistance drivers. This EA integration approach also suggests new antibiotic resistance genes which are then shown to provide a fitness advantage in competition experiments. Moreover, EA integration analysis of clinical and environmental isolates of antibiotic resistant of E. coli identifies gene drivers of resistance where a standard approach fails. Together these results inform the genetic basis of de novo colistin resistance and support the robust discovery of phenotype-driving genes via the evolutionary action of genetic perturbations in fitness landscapes.

SUBMITTER: Marciano DC

PROVIDER: S-EPMC9184624 | biostudies-literature | 2022 Jun

REPOSITORIES: biostudies-literature

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Evolutionary action of mutations reveals antimicrobial resistance genes in Escherichia coli.

Marciano David C DC Wang Chen C Hsu Teng-Kuei TK Bourquard Thomas T Atri Benu B Nehring Ralf B RB Abel Nicholas S NS Bowling Elizabeth A EA Chen Taylor J TJ Lurie Pamela D PD Katsonis Panagiotis P Rosenberg Susan M SM Herman Christophe C Lichtarge Olivier O

Nature communications 20220609 1

Since antibiotic development lags, we search for potential drug targets through directed evolution experiments. A challenge is that many resistance genes hide in a noisy mutational background as mutator clones emerge in the adaptive population. Here, to overcome this noise, we quantify the impact of mutations through evolutionary action (EA). After sequencing ciprofloxacin or colistin resistance strains grown under different mutational regimes, we find that an elevated sum of the evolutionary ac ...[more]

PMID: 35680894

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Project description:Antimicrobial resistance pose a global thread nowadays. Compounds of natural origin are an important source of drugs used in clinical practice. However, it is important to understand both their principles of efficacy and their molecular mechanism of action. In this study we evaluated antimicrobial potential of t-cinnamaldehyde which is an organic compound found in many plant species, especially in the Cinnamomum genus, such as Cinnamomum zeylanicum and cassia. Cinnamon oil extracted from the bark of these plants contains up to 80% trans-cinnamaldehyde. Although CNMA has shown antimicrobial properties against numerous Gram+ and Gram- species, its mode of action against pathogens remains not fuly elucidated. Therefore, this project aims to determine CNMA activity at the level of gene expression. Total RNA was isolated and checked for quality using the Bioanalyzer 2100. The sequencing run was conducted on the Illumina NovaSeq6000 platform. 30 million pair-end reads per samples were assessed with 101 pb read length. Reference E. coli MG1655 genome sequence and annotations were downloaded from GenBank. Differentially expressed analysis of 0.25 x MIC CNMA was performed against untreated control in indicated time with p ≤ 0.001 and log2FC ≥ 1.5. We have discovered many changes bacterial transcriptome. For instance: following the treatment with 0.25×MIC of CNMA, we found 292 and 140 upregulated and 107 and 96 downregulated genes at time points 30 and 60 min, respectively. Among the most enriched genes, were those related to the tricarboxylic acid (TCA) cycle, flagellum synthesis, amino acid transport, and oxidoreductase activity. According to these findings we can conclude that observed transcriprional pattern indicates severe metabolic downshift in treated cells, and consequently activation of stress processes. These was in line with our secondary experiments which revealed drop in growth kinnetic, cytoplasm shrinkage, NAD/NADH level alteration and elevation of stringent response alarmones ((p)ppGpp). Taken together, this suggests that CNMA-treated E. coli bacteria undergo major metabolic changes that finally result in cell death.

Project description:Escherichia coli often carries linked antimicrobial resistance genes on transmissible genetic elements. Through coselection, antimicrobial use may select for unrelated but linked resistance or virulence genes. This study used unconditional statistical associations to investigate the relationships between antimicrobial resistance phenotypes and antimicrobial resistance genes in 151 E. coli isolates from healthy pigs. Phenotypic resistance to each drug was significantly associated with phenotypic resistance to at least one other drug, and every association found that the probability of observing the outcome resistance was increased by the presence of the predictor resistance. With one exception, each statistical association that was identified between a pair of resistance genes had a corresponding significant association identified between the phenotypes mediated by those genes. This suggests that associations between resistance phenotypes might predict coselection. If this hypothesis is confirmed, evaluation of the associations between resistance phenotypes could improve our knowledge of coselection dynamics and provide a cost-effective way to evaluate existing data until large-scale genotypic data collection becomes feasible. This could enable policy makers and users of antimicrobials to consider coselection in antimicrobial use decisions. This study also considered the unconditional relationships between resistance and virulence genes in E. coli from healthy pigs (aidA-1, eae, elt, estA, estB, fedA1, stx1, and stx2). Positive statistical associations would suggest that antimicrobial use may select for virulence in bacteria that may contaminate food or cause diarrhea in pigs. Fortunately, the odds of detecting a virulence gene were rarely increased by the presence of an antimicrobial resistance gene. This suggests that on-farm antimicrobial use did not select for the examined virulence factors in E. coli carried by this population of healthy pigs.

Project description:BACKGROUND & OBJECTIVES: Diverse mechanisms have been identified in enteric bacteria for their adaptation and survival against multiple classes of antimicrobial agents. Resistance of bacteria to the most effective fluoroquinolones have increasingly been reported in many countries. We have identified that most of the enterotoxigenic Escherichia coli (ETEC) were resistant to several antimicrobials in a diarrhoea outbreak at Ahmedabad during 2000. The present study was done to identify several genes responsible for antimicrobial resistance and mobile genetic elements in the ETEC strains. METHODS: Seventeen ETEC strains isolated from diarrhoeal patients were included in this study. The antimicrobial resistance was confirmed by conventional disc diffusion method. PCR and DNA sequencing were performed for the identification of mutation in the quinolone resistance-determining regions (QRDRs). Efflux pump was tested by inhibiting the proton-motive force. DNA hybridization assay was made for the detection of integrase genes and the resistance gene cassettes were identified by direct sequencing of the PCR amplicons. RESULTS: Majority of the ETEC had GyrA mutations at codons 83 and 87 and in ParC at codon 80. Six strains had an additional mutation in ParC at codon 108 and two had at position 84. Plasmid-borne qnr gene alleles that encode quinolone resistance were not detected but the newly described aac(6')-Ib-cr gene encoding a fluoroquinolne-modifying enzyme was detected in 64.7 per cent of the ETEC. Class 1 (intI1) and class 2 (intI2) integrons were detected in six (35.3%) and three (17.6%) strains, respectively. Four strains (23.5%) had both the classes of integrons. Sequence analysis revealed presence of dfrA17, aadA1, aadA5 in class 1, and dfrA1, sat1, aadA1 in class 2 integrons. In addition, the other resistance genes such as tet gene alleles (94.1%), catAI (70.6%), strA (58.8%), bla TEM-1 (35.2%), and aphA1-Ia (29.4%) were detected in most of the strains. INTERPRETATION & CONCLUSIONS: Innate gene mutations and acquisition of multidrug resistance genes through mobile genetic elements might have contributed to the emergence of multidrug resistance (MDR) in ETEC. This study reinforces the necessity of utilizing molecular techniques in the epidemiological studies to understand the nature of resistance responsible for antimicrobial resistance in different species of pathogenic bacteria.

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Evolutionary action of mutations reveals antimicrobial resistance genes in Escherichia coli.

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Evolutionary action of mutations reveals antimicrobial resistance genes in Escherichia coli.

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