Dataset Information

Whole-Genome Sequencing Accurately Identifies Resistance to Extended-Spectrum ?-Lactams for Major Gram-Negative Bacterial Pathogens.

ABSTRACT: There is marked interest in using DNA-based methods to detect antimicrobial resistance (AMR), with targeted polymerase chain reaction (PCR) approaches increasingly being incorporated into clinical care. Whole-genome sequencing (WGS) could offer significant advantages over targeted PCR for AMR detection, particularly for species where mutations are major drivers of AMR.Illumina MiSeq WGS and broth microdilution (BMD) assays were performed on 90 bloodstream isolates of the 4 most common gram-negative bacteria causing bloodstream infections in neutropenic patients. The WGS data, including both gene presence/absence and detection of mutations in an array of AMR-relevant genes, were used to predict resistance to 4 ?-lactams commonly used in the empiric treatment of neutropenic fever. The genotypic predictions were then compared to phenotypic resistance as determined by BMD and by commercial methods during routine patient care.Of 133 putative instances of resistance to the ?-lactams of interest identified by WGS, only 87 (65%) would have been detected by a typical PCR-based approach. The sensitivity, specificity, and positive and negative predictive values for WGS in predicting AMR were 0.87, 0.98, 0.97, and 0.91, respectively. Using BMD as the gold standard, our genotypic resistance prediction approach had a significantly higher positive predictive value compared to minimum inhibitory concentrations generated by commercial methods (0.97 vs 0.92; P = .025).These data demonstrate the potential feasibility of using WGS to guide antibiotic treatment decisions for patients with life-threatening infections for an array of medically important pathogens.

SUBMITTER: Shelburne SA

PROVIDER: S-EPMC5850535 | biostudies-literature | 2017 Sep

REPOSITORIES: biostudies-literature

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Publications

Whole-Genome Sequencing Accurately Identifies Resistance to Extended-Spectrum β-Lactams for Major Gram-Negative Bacterial Pathogens.

Shelburne Samuel A SA Kim Jiwoong J Munita Jose M JM Sahasrabhojane Pranoti P Shields Ryan K RK Press Ellen G EG Li Xiqi X Arias Cesar A CA Cantarel Brandi B Jiang Ying Y Kim Min S MS Aitken Samuel L SL Greenberg David E DE

Clinical infectious diseases : an official publication of the Infectious Diseases Society of America 20170901 5

<h4>Background</h4>There is marked interest in using DNA-based methods to detect antimicrobial resistance (AMR), with targeted polymerase chain reaction (PCR) approaches increasingly being incorporated into clinical care. Whole-genome sequencing (WGS) could offer significant advantages over targeted PCR for AMR detection, particularly for species where mutations are major drivers of AMR.<h4>Methods</h4>Illumina MiSeq WGS and broth microdilution (BMD) assays were performed on 90 bloodstream isola ...[more]

PMID: 28472260

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Project description:BackgroundInfections caused by extended-spectrum beta-lactamases (ESBL) producing Gram-negative bacteria has emerge as a global threat in clinical practices. The treat is more serious in developing countries due to inappropriate use, poor adherence, use of counterfeit, sub-standard antibiotics and poor infection control practices. Data on ESBL producing Gram-negative bacteria are limited in developing countries including Ethiopia. The aim of this study was therefore, to describe the burden of ESBL producing Gram negative pathogens isolated from patients attending at Felege Hiwot Comprehensive Specialized Hospital, Bahir Dar, Amhara region.Materials and methodsA total of 532 clinical samples of blood, urine, stool, wound, abscess, ear discharge, nasal discharge, cervical discharge and body fluid specimens were aseptically collected and bacteriologically processed. Identification of the bacterial species was performed using an automated system (Vitek-2 Compact 27530, USA) and antibiotic susceptibility test was determined by disk diffusion method and selection of antibiotics were in accordance with CLSI guidelines. The MDR pattern of the Gram-negative pathogens was assessed using phenotypic methods of ESBL and carbapenemase production following standard procedure.ResultA total of 532 samples were processed and 263 pathogens were isolated. Of these, 185 (70.3%) were Gram-negative and 78 (29.7%) Gram-positive. Of the Gram-negative bacteria the high proportion of the isolates were identified from blood 146/185 (78.9%) and 29/185 (15.7%) were from urine cultures. The most common isolate in all clinical samples was Klebsiella pneumoniae 97/185 (52.4%) followed by Escherichia coli 23/185 (12.4%), Acinetobacter baumannii 15/185 (17.6%) and Enterobacter aerogenes 12/185(6.5%). Of the total Gram negatives, the prevalence of MDR was 148/185 (80.0%). Of the MDR isolates the prevalence of ESBL producers were, 127/148 (85.8%) and 24/148 (16.2%) were carbapenemase producers.Conclusion and recommendationPrevalence of MDR and ESBL producing Gram-negative pathogens in this hospital is alarmingly high. Therefore, continuous monitoring of the problem with effective infection prevention and careful selection of empirical therapy are warranted in the study area.

Project description:The development of new antibiotics is imperative to fight increasing mortality rates connected to infections caused by multidrug-resistant (MDR) bacteria. In this context, Gram-negative pathogens listed in the WHO priority list are particularly problematic. Darobactin is a ribosomally produced and post-translationally modified bicyclic heptapeptide antibiotic selectively killing Gram-negative bacteria by targeting the outer membrane protein BamA. The native darobactin A producer Photorhabdus khanii HGB1456 shows very limited production under laboratory cultivation conditions. Herein, we present the design and heterologous expression of a synthetically engineered darobactin biosynthetic gene cluster (BGC) in Escherichia coli to reach an average darobactin A production titre of 13.4 mg L-1. Rational design of darA variants, encoding the darobactin precursor peptide with altered core sequences, resulted in the production of 13 new 'non-natural' darobactin derivatives and 4 previously hypothetical natural darobactins. One of the non-natural compounds, darobactin 9, was more potent than darobactin A, and showed significantly improved activity especially against Pseudomonas aeruginosa (0.125 μg mL-1) and Acinetobacter baumannii (1-2 μg mL-1). Importantly, it also displayed superior activity against MDR clinical isolates of E. coli (1-2 μg mL-1) and Klebsiella pneumoniae (1-4 μg mL-1). Independent deletions of genes from the darobactin BGC showed that only darA and darE, encoding a radical forming S-adenosyl-l-methionine-dependent enzyme, are required for darobactin formation. Co-expression of two additional genes associated with the BGCs in hypothetical producer strains identified a proteolytic detoxification mechanism as a potential self-resistance strategy in native producers. Taken together, we describe a versatile heterologous darobactin platform allowing the production of unprecedented active derivatives in good yields, and we provide first experimental evidence for darobactin biosynthesis processes.

Dataset Information

Whole-Genome Sequencing Accurately Identifies Resistance to Extended-Spectrum ?-Lactams for Major Gram-Negative Bacterial Pathogens.

Publications

Whole-Genome Sequencing Accurately Identifies Resistance to Extended-Spectrum β-Lactams for Major Gram-Negative Bacterial Pathogens.

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