ABSTRACT
As an emerging technology, Rapid DNA has demonstrated its utility for law enforcement in the provision of DNA profiling data at the point of arrest, often not requiring analyst review of the profiles generated. Recently, efforts have centred on the evaluation of Rapid DNA (without analyst review) and modified Rapid DNA (requiring review by a trained analyst) for application to crime scene samples. In a broader forensic context, however, another application for Rapid DNA is its use to process post-mortem samples to assist with the identification of deceased persons; and while gaps in our knowledge remain as to how Rapid DNA instruments perform with these sample types (often compromised with regards to their yield and quality of DNA), they have been successfully deployed in the field to assist in the identification of disaster victims (as exemplified during the 2018 Californian wildfire). This review aims to provide the current research landscape for the forensic application of Rapid DNA as an emerging technology from a Disaster Victim Identification perspective.
Subject(s)
Disaster Victims , DNA/genetics , DNA Fingerprinting , Humans , Law EnforcementABSTRACT
BACKGROUND: Carbapenemase-producing Enterobacterales (CPE) can colonize the gut and are of major clinical concern. Identification of CPE colonization is problematic; there is no gold-standard detection method, and the effects of antibiotic exposure and microbiota dysbiosis on detection are unknown. AIM: Based on a national survey we selected four CPE screening assays in common use. We used a clinically reflective in vitro model of human gut microbiota to investigate the performance of each test to detect three different CPE strains under different, clinically relevant antibiotic exposures. METHODS: Twelve gut models were seeded with a pooled faecal slurry and exposed to CPE either before, after, concomitant with, or in the absence of piperacillin-tazobactam (358 mg/L, 3 × daily, seven days). Total Enterobacterales and CPE populations were enumerated daily. Regular screening for CPE was performed using Cepheid Xpert® Carba-R molecular test, and with Brilliance™ CRE, Colorex™ mSuperCARBA and CHROMID® CARBA SMART agars. FINDINGS: Detection of CPE when the microbiota are intact is problematic. Antibiotic exposure disrupts microbiota populations and allows CPE proliferation, increasing detection. The performances of assays varied, particularly with respect to different CPE strains. The Cepheid assay performed better than the three agar methods for detecting a low level of CPE within an intact microbiota, although performance of all screening methods was comparable when CPE populations increased in a disrupted microbiota. CONCLUSION: CPE strains differed in their dynamics of colonization in an in vitro gut model and in their subsequent response to antibiotic exposure. This affected detection by molecular and screening methods, which has implications for the sensitivity of CPE screening in healthcare settings.
Subject(s)
Enterobacteriaceae Infections , Gastrointestinal Microbiome , Microbiota , Bacterial Proteins , Bacteriological Techniques , Dysbiosis/diagnosis , Enterobacteriaceae Infections/diagnosis , Humans , Sensitivity and Specificity , beta-LactamasesABSTRACT
This paper reports the emergence of Candida auris infections in an intensive care unit at a hospital in Moscow. Forty-nine cases were diagnosed in 2016-2017, and the risk factors and antifungal susceptibilities are described. The 30-day all-cause mortality for 19 bloodstream infections in patients who did not receive appropriate antifungal therapy was 42.1%. Phylogenetic analysis of the internal transcribed spacer and D1-D2 regions and K143R substitution in the ERG11 gene indicated that the studied C. auris strains were of South Asian origin. This first reported series of C. auris infections in Russia demonstrates the rapid dissemination of this species, and the need for international surveillance and control measures.
Subject(s)
Candida/isolation & purification , Candidemia/epidemiology , Cross Infection/epidemiology , Adolescent , Adult , Aged , Aged, 80 and over , Antifungal Agents/therapeutic use , Candidemia/drug therapy , Candidemia/microbiology , Candidemia/mortality , Cluster Analysis , Cross Infection/microbiology , Cross Infection/mortality , DNA, Fungal/chemistry , DNA, Fungal/genetics , DNA, Ribosomal/chemistry , DNA, Ribosomal/genetics , DNA, Ribosomal Spacer/chemistry , DNA, Ribosomal Spacer/genetics , Female , Humans , Intensive Care Units , Male , Microbial Sensitivity Tests , Middle Aged , Moscow , Phylogeny , RNA, Ribosomal/genetics , Risk Factors , Sequence Analysis, DNA , Survival Analysis , Young AdultABSTRACT
BACKGROUND: An electronic reporting system (ERS) for the enhanced surveillance of carbapenemase-producing Gram-negative bacteria (CPGNB) was launched by Public Health England in May 2015. AIM: This evaluation aimed to assess uptake, timeliness and completeness of data provided and explore potential barriers and facilitators to adopting the system. METHODS: The evaluation comprised a retrospective analysis of surveillance data and semi-structured interviews with ERS users. FINDINGS: The proportion of organisms referred for investigation of carbapenem resistance via ERS increased over the first 12â¯months post-implementation from 35% to 73%; uptake varied widely across regions of England. Completeness of enhanced data fields was poor in 78% of submitted isolates. The median number of days to report confirmatory test results via ERS was 1â¯day for the regional service and nine days for the national reference laboratory, which additionally conducts phenotypic testing to confirm carbapenemase negativity. Hindrances to ERS utility included: a lack of designated, ongoing resource for system maintenance, technical support and development; uncertainty about how and when to use ERS and workload. Incomplete data prevented gaining a better understanding of important risk factors and transmission routes of CPGNB in England. CONCLUSION: The ERS is the only surveillance system in England with the potential to gather intelligence on important risk factors for CPGNB to inform public health measures to control their spread. Although the ERS captures more information on CPGNB than other surveillance systems, timeliness and completeness of the enhanced data require substantial improvements in order to deliver the desired health benefits.
Subject(s)
Bacterial Proteins/analysis , Disease Notification/methods , Electronic Data Processing/methods , Epidemiological Monitoring , Gram-Negative Bacteria/enzymology , Gram-Negative Bacterial Infections/epidemiology , Gram-Negative Bacterial Infections/microbiology , beta-Lactamases/analysis , England , Gram-Negative Bacteria/isolation & purification , Health Services Research , Interviews as Topic , Retrospective StudiesABSTRACT
BACKGROUND: The incidence of Escherichia coli bacteraemia in England is increasing amid concern regarding the roles of antimicrobial resistance and nosocomial acquisition on burden of disease. AIM: To determine the relative contributions of hospital-onset E. coli bloodstream infection and specific E. coli antimicrobial resistance patterns to the burden and severity of E. coli bacteraemia in West London. METHODS: Patient and antimicrobial susceptibility data were collected for all cases of E. coli bacteraemia between 2011 and 2015. Multivariable logistic regression was used to determine the association between the category of infection (hospital or community-onset) and length of stay, intensive care unit admission, and 30-day all-cause mortality. FINDINGS: E. coli bacteraemia incidence increased by 76% during the study period, predominantly due to community-onset cases. Resistance to quinolones, third-generation cephalosporins, and aminoglycosides also increased over the study period, occurring in both community- and hospital-onset cases. Hospital-onset and non-susceptibility to either quinolones or third-generation cephalosporins were significant risk factors for prolonged length of stay, as was older age. Rates of mortality were 7% and 12% at 7 and 30 days, respectively. Older age, a higher comorbidity score, and bacteraemia caused by strains resistant to three antibiotic classes were all significant risk factors for mortality at 30 days. CONCLUSION: Multidrug resistance, increased age, and comorbidities were the main drivers of adverse outcome. The rise in E. coli bacteraemia was predominantly driven by community-onset infections, and initiatives to prevent community-onset cases should be a major focus to reduce the quantitative burden of E. coli infection.
Subject(s)
Bacteremia/epidemiology , Drug Resistance, Bacterial , Escherichia coli Infections/epidemiology , Escherichia coli/drug effects , Adolescent , Adult , Aged , Aged, 80 and over , Bacteremia/microbiology , Bacteremia/mortality , Escherichia coli/isolation & purification , Escherichia coli Infections/microbiology , Escherichia coli Infections/mortality , Female , Humans , Incidence , Length of Stay , London/epidemiology , Male , Microbial Sensitivity Tests , Middle Aged , Regression Analysis , Retrospective Studies , Risk Factors , Survival Analysis , Young AdultABSTRACT
Multi-drug-resistant Gram-negative bacteria are of major clinical concern. The increasing prevalence of carbapenemase-producing Enterobacteriaceae (CPE), resistant to all beta-lactams including carbapenems and able to colonize the large intestine, represents a key threat. Rapid, accurate detection of intestinal CPE colonization is critical to minimize transmission, and hence reduce costly, difficult-to-treat CPE infections. There is currently no 'gold standard' CPE detection method. A survey of diagnostic laboratories in England found considerable heterogeneity in diagnostic CPE testing methods and procedures.
Subject(s)
Carbapenem-Resistant Enterobacteriaceae/isolation & purification , Carrier State/diagnosis , Diagnostic Tests, Routine/methods , Enterobacteriaceae Infections/diagnosis , Epidemiological Monitoring , Health Services Research , Mass Screening/methods , Carrier State/microbiology , England , Enterobacteriaceae Infections/microbiology , Health Policy , Hospitals , Humans , Organizational PolicyABSTRACT
Carbapenem-resistant Enterobacteriaceae (CRE) represent a health threat, but effective control interventions remain unclear. Hospital wastewater sites are increasingly being highlighted as important potential reservoirs. We investigated a large Klebsiella pneumoniae carbapenemase (KPC)-producing Escherichia coli outbreak and wider CRE incidence trends in the Central Manchester University Hospital NHS Foundation Trust (CMFT) (United Kingdom) over 8 years, to determine the impact of infection prevention and control measures. Bacteriology and patient administration data (2009 to 2017) were linked, and a subset of CMFT or regional hospital KPC-producing E. coli isolates (n = 268) were sequenced. Control interventions followed international guidelines and included cohorting, rectal screening (n = 184,539 screens), environmental sampling, enhanced cleaning, and ward closure and plumbing replacement. Segmented regression of time trends for CRE detections was used to evaluate the impact of interventions on CRE incidence. Genomic analysis (n = 268 isolates) identified the spread of a KPC-producing E. coli outbreak clone (strain A, sequence type 216 [ST216]; n = 125) among patients and in the environment, particularly on 2 cardiac wards (wards 3 and 4), despite control measures. ST216 strain A had caused an antecedent outbreak and shared its KPC plasmids with other E. coli lineages and Enterobacteriaceae species. CRE acquisition incidence declined after closure of wards 3 and 4 and plumbing replacement, suggesting an environmental contribution. However, ward 3/ward 4 wastewater sites were rapidly recolonized with CRE and patient CRE acquisitions recurred, albeit at lower rates. Patient relocation and plumbing replacement were associated with control of a clonal KPC-producing E. coli outbreak; however, environmental contamination with CRE and patient CRE acquisitions recurred rapidly following this intervention. The large numbers of cases and the persistence of blaKPC in E. coli, including pathogenic lineages, are of concern.
Subject(s)
Cross Infection/epidemiology , Disease Outbreaks , Escherichia coli Infections/epidemiology , Escherichia coli/genetics , Klebsiella pneumoniae/genetics , beta-Lactamases/genetics , Cross Infection/drug therapy , Cross Infection/microbiology , Cross Infection/transmission , DNA, Bacterial/genetics , Disease Reservoirs/microbiology , Escherichia coli/drug effects , Escherichia coli/isolation & purification , Escherichia coli/pathogenicity , Escherichia coli Infections/drug therapy , Escherichia coli Infections/microbiology , Escherichia coli Infections/transmission , Gene Expression , Gene Transfer, Horizontal , Genotype , Hospitals, University , Humans , Infection Control/methods , Klebsiella pneumoniae/pathogenicity , Medical Waste , Phylogeny , Prevalence , United Kingdom/epidemiology , Wastewater/microbiologyABSTRACT
A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.
ABSTRACT
This study aimed to determine prevalence of Ralstonia spp. in cystic fibrosis patients, look for any evidence of cross infection and to describe clinical outcomes for patients infected by Ralstonia spp. Prevalence of Ralstonia spp. was calculated annually from 2008 to 2016. Pulsed-field gel electrophoresis was performed on ⩾1 sample from patients with an isolation of Ralstonia spp. between 2008 and 2016. A prospective, longitudinal observational study of adult patients was performed with 12 months follow-up from recruitment. Prevalence of Ralstonia spp. rose from 0·6% in 2008 to 2·4% in 2016. In total 12 out of 14 (86%) patients with ⩾1 isolation of Ralstonia spp. developed chronic infection. A pair and a group of three unrelated patients with epidemiological connections shared strains of Ralstonia mannitolilytica. Lung function of Ralstonia spp. infected patients was moderately to severely impaired. Prevalence of Ralstonia spp. is low but increasing. The risk of a patient developing chronic Ralstonia spp. infection following first acquisition is high and cross-infection may be possible. Whether Ralstonia spp. infection causes increased pulmonary exacerbation frequency and lung function decline needs to be evaluated in larger prospective studies.
Subject(s)
Cross Infection/epidemiology , Cystic Fibrosis/complications , Cystic Fibrosis/epidemiology , Gram-Negative Bacterial Infections/complications , Gram-Negative Bacterial Infections/epidemiology , Ralstonia/isolation & purification , Adolescent , Adult , Comorbidity , Cross Infection/microbiology , Cystic Fibrosis/therapy , Electrophoresis, Gel, Pulsed-Field , England/epidemiology , Female , Gram-Negative Bacterial Infections/microbiology , Humans , Longitudinal Studies , Male , Prevalence , Prospective Studies , Ralstonia/classification , Risk , Young AdultABSTRACT
AIM: To describe an outbreak of colonization by linezolid- and glycopeptide-resistant Enterococcus faecium harbouring the cfr gene in a UK nephrology unit. METHODS: Isolates of linezolid-resistant E. faecium were typed by pulsed-field gel electrophoresis (PFGE), and examined by polymerase chain reaction (PCR) and sequencing for the transmissible cfr gene that confers resistance to linezolid. Enhanced environmental cleaning, initial and weekly screening of all patients, and monitoring of adherence to standard infection control precautions were implemented. FINDINGS: Five patients with pre-existing renal disease were found to have rectal colonization with linezolid-resistant E. faecium over a two-week period. The index case was a 57-year-old male from India who had travelled to the UK. One patient also had a linezolid-resistant E. faecium of a different PFGE profile isolated from a heel wound. All isolates were confirmed to harbour the cfr gene by PCR and Sanger sequencing, and all were resistant to glycopeptides (VanA phenotype). CONCLUSIONS: This article describes the first UK outbreak with a single strain of linezolid- and glycopeptide-resistant E. faecium harbouring the cfr gene, affecting five patients in a nephrology unit. Following the implementation of aggressive infection control measures, no further cases were detected beyond a two-week period.
Subject(s)
Anti-Bacterial Agents/pharmacology , Carrier State/epidemiology , Drug Resistance, Bacterial , Enterococcus faecium/drug effects , Glycopeptides/pharmacology , Gram-Positive Bacterial Infections/epidemiology , Linezolid/pharmacology , Carrier State/microbiology , Cross Infection/epidemiology , Cross Infection/microbiology , Electrophoresis, Gel, Pulsed-Field , Enterococcus faecium/classification , Enterococcus faecium/genetics , Enterococcus faecium/isolation & purification , Genes, Bacterial , Genotype , Gram-Positive Bacterial Infections/microbiology , Hospital Departments , Humans , Infection Control/methods , Male , Middle Aged , Polymerase Chain Reaction , Sequence Analysis, DNA , United KingdomABSTRACT
The expanding global distribution of multi-resistant Klebsiella pneumoniae demands faster antimicrobial susceptibility testing (AST) to guide antibiotic treatment. Current ASTs rely on time-consuming differentiation of resistance and susceptibility after initial isolation of bacteria from a clinical specimen. Here we describe a flow cytometry workflow to determine carbapenem susceptibility from bacterial cell characteristics in an international K. pneumoniae isolate collection (n = 48), with a range of carbapenemases. Our flow cytometry-assisted susceptibility test (FAST) method combines rapid qualitative susceptible/non-susceptible classification and quantitative MIC measurement in a single process completed shortly after receipt of a primary isolate (54 and 158 minutes respectively). The qualitative FAST results and FAST-derived MIC (MICFAST) correspond closely with broth microdilution MIC (MICBMD, Matthew's correlation coefficient 0.887), align with the international AST standard (ISO 200776-1; 2006) and could be used for rapid determination of antimicrobial susceptibility in a wider range of Gram negative and Gram positive bacteria.
ABSTRACT
BACKGROUND: Antimicrobial resistance is an emerging global health issue. Data on the epidemiology of multidrug-resistant organisms are scarce for Africa, especially in HIV-infected individuals who often have frequent contact with healthcare. We investigated the prevalence of extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-E) carriage in stool among HIV-infected children attending an HIV outpatient department in Harare, Zimbabwe. METHODS: We recruited children who were stable on antiretroviral therapy (ART) attending a HIV clinic from August 2014 to June 2015. Information was collected on antibiotic use and hospitalization. Stool was tested for ESBL-E through combination disc diffusion. API20E identification and antimicrobial susceptibility was performed on the positive samples followed by whole genome sequencing. RESULTS: Stool was collected from 175/202 (86.6â%) children. Median age was 11 [inter-quartile range (IQR) 9-12] years. Median time on ART was 4.6 years (IQR 2.4-6.4). ESBL-Es were found in 24/175 samples (13.7â%); 50â% of all ESBL-Es were resistant to amoxicillin-clavulanate, 100â% to co-trimoxazole, 45.8â% to chloramphenicol, 91.6â% to ceftriaxone, 20.8â% to gentamicin and 62.5â% to ciprofloxacin. ESBL-Es variously encoded CTX-M, OXA, TEM and SHV enzymes. The odds of ESBL-E carriage were 8.5 times (95â% CI 2.2-32.3) higher in those on ART for less than one year (versus longer) and 8.5 times (95â% CI 1.1-32.3) higher in those recently hospitalized for a chest infection. CONCLUSION: We found a 13.7â% prevalence of ESBL-E carriage in a population where ESBL-E carriage has not been described previously. Antimicrobial resistance (AMR) in Africa merits further study, particularly given the high HIV prevalence and limited diagnostic and therapeutic options available.
Subject(s)
Carrier State/epidemiology , Enterobacteriaceae Infections/complications , Enterobacteriaceae Infections/epidemiology , Enterobacteriaceae/enzymology , Enterobacteriaceae/isolation & purification , HIV Infections/complications , beta-Lactamases/biosynthesis , Adolescent , Ambulatory Care , Anti-Bacterial Agents , Antiretroviral Therapy, Highly Active , CD4 Lymphocyte Count , Carrier State/microbiology , Child , Ciprofloxacin/pharmacology , Enterobacteriaceae/drug effects , Enterobacteriaceae/genetics , Enterobacteriaceae Infections/microbiology , Feces/microbiology , Female , HIV Infections/drug therapy , HIV Infections/epidemiology , HIV Infections/virology , Humans , Male , Microbial Sensitivity Tests , Prevalence , Zimbabwe/epidemiology , beta-Lactamases/geneticsABSTRACT
Objectives: Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacteriaceae were first seen in the UK in 2003 and have been increasingly reported since 2010, largely owing to an ongoing outbreak in North-West England. We examined the role of clonal spread and plasmid transmission in their emergence. Methods: Isolates comprised KPC-positive K. pneumoniae ( n = 33), Escherichia coli ( n = 7) and Enterobacter spp. ( n = 4) referred to the national reference laboratory between 2008 and 2010 from 17 UK centres, including three in North-West England. Isolates were typed by MLST. Plasmids were transferred by electroporation and characterized by PCR or sequencing. PCR screening assays were developed to distinguish plasmid pKpQIL variants. Results: The K. pneumoniae isolates included 10 STs, of which three belonged to clonal group (CG) 258. CG258 ( n = 19) isolates were detected in 13 centres but accounted for only 7/19 (36.8%) of those from North-West England. Most KPC-producers (37/44, 84.1%), including 16/19 CG258 K. pneumoniae , carried bla KPC on IncFII K2 plasmids. Sequencing of a subset of these plasmids ( n = 11) revealed similarities with published pKpQIL. One variant, pKpQIL-UK [identified in K. pneumoniae CG258 ( n = 5) and ST468 ( n = 1) isolates from distinct centres] had only a few nucleotide changes from classical pKpQIL, whereas pKpQIL-D1 ( n = 1) and pKpQIL-D2 ( n = 4), from isolates of various species in the North-West, harboured large variations, reflecting replacement of the partitioning and replication functions and potentially thereby facilitating spread. PCR revealed that 36/37 (97.3%) IncFII K2 -type plasmids in KPC-positive isolates had pKpQIL markers. Conclusions: pKpQIL-like plasmids played a major role in the early dissemination of KPC enzymes in the UK.
Subject(s)
Bacterial Proteins/genetics , Enterobacteriaceae Infections/epidemiology , Enterobacteriaceae Infections/microbiology , Enterobacteriaceae/enzymology , Plasmids , beta-Lactamases/genetics , Disease Transmission, Infectious , Enterobacteriaceae/classification , Enterobacteriaceae/genetics , Enterobacteriaceae/isolation & purification , Gene Transfer, Horizontal , Molecular Epidemiology , Multilocus Sequence Typing , Polymerase Chain Reaction , Sequence Analysis, DNA , United Kingdom/epidemiologyABSTRACT
OBJECTIVES: The introduction of metagenomic sequencing to diagnostic microbiology has been hampered by slowness, cost and complexity. We explored whether MinION nanopore sequencing could accelerate diagnosis and resistance profiling, using complicated urinary tract infections as an exemplar. METHODS: Bacterial DNA was enriched from clinical urines (nâ=â10) and from healthy urines 'spiked' with multiresistant Escherichia coli (nâ=â5), then sequenced by MinION. Sequences were analysed using external databases and bioinformatic pipelines or, ultimately, using integrated real-time analysis applications. Results were compared with Illumina data and resistance phenotypes. RESULTS: MinION correctly identified pathogens without culture and, among 55 acquired resistance genes detected in the cultivated bacteria by Illumina sequencing, 51 were found by MinION sequencing directly from the urines; with three of the four failures in an early run with low genome coverage. Resistance-conferring mutations and allelic variants were not reliably identified. CONCLUSIONS: MinION sequencing comprehensively identified pathogens and acquired resistance genes from urine in a timeframe similar to PCR (4 h from sample to result). Bioinformatic pipeline optimization is needed to better detect resistances conferred by point mutations. Metagenomic-sequencing-based diagnosis will enable clinicians to adjust antimicrobial therapy before the second dose of a typical (i.e. every 8 h) antibiotic.
Subject(s)
Bacteria/isolation & purification , Bacterial Infections/diagnosis , Metagenomics/methods , Microbial Sensitivity Tests/methods , Nanopores , Urinary Tract Infections/diagnosis , Urine/microbiology , Bacteria/drug effects , Bacterial Infections/microbiology , Computational Biology/methods , High-Throughput Nucleotide Sequencing/methods , Humans , Time Factors , Urinary Tract Infections/microbiologyABSTRACT
We determined the prevalence and types of extended-spectrum ß-lactamase (ESBL)-producing and carbapenem-resistant Escherichia coli in raw retail beef, chicken, pork, fruit and vegetables in five UK regions in 2013-14. Raw meat (n=397), and fruit and vegetable samples (n=400) were purchased from retail stores in London, East Anglia, North West England, Scotland and Wales. Samples were tested for the presence of ESBL-producing E. coli by plating enriched samples on CHROMagar CTX and CHROMagar ESBL, for AmpC-type E. coli by plating on "CHROMagar FOX" (CHROMagar ECC+16mg/L cefoxitin), and for carbapenem-resistant E. coli by plating on CHROMagar KPC. Additionally, pre-enrichment counts were performed on the above agars, and on CHROMagar ECC. Isolates of interest were characterised by MALDI-ToF to confirm identification, by PCR for blaCIT,blaCTX-M,blaOXA, blaSHV and blaTEM genes; ESBL or blaCIT genes were sequenced. Only 1.9% and 2.5% of beef and pork samples, respectively were positive for ESBL-producing E. coli after enrichment compared with 65.4% of chicken samples. 85.6% positive samples from chicken meat carried blaCTX-M-1; blaCTX-M-15 was not detected. None of the fruits or vegetables yielded ESBL-producing E. coli and none of the meat, fruit or vegetable samples yielded carbapenem-resistant E. coli. Retail chicken was more frequently a source of ESBL-producing E. coli than were beef, pork, fruit or vegetables. None of the foodstuffs yielded E. coli with CTX-M-15 ESBL, which dominates in human clinical isolates in the UK, and none yielded carbapenem-resistant E. coli.
Subject(s)
Anti-Bacterial Agents/pharmacology , Carbapenems/pharmacology , Escherichia coli/drug effects , Food Contamination/analysis , Fruit/microbiology , Meat/microbiology , Vegetables/microbiology , beta-Lactamases/metabolism , Animals , Cattle , Chickens , Drug Resistance, Bacterial , Escherichia coli/enzymology , Escherichia coli/genetics , Escherichia coli/isolation & purification , Food Contamination/economics , Humans , Meat/economics , Polymerase Chain Reaction , Prevalence , Swine , United Kingdom , beta-Lactamases/geneticsABSTRACT
Whole genome sequencing (WGS) offers the potential to predict antimicrobial susceptibility from a single assay. The European Committee on Antimicrobial Susceptibility Testing established a subcommittee to review the current development status of WGS for bacterial antimicrobial susceptibility testing (AST). The published evidence for using WGS as a tool to infer antimicrobial susceptibility accurately is currently either poor or non-existent and the evidence / knowledge base requires significant expansion. The primary comparators for assessing genotypic-phenotypic concordance from WGS data should be changed to epidemiological cut-off values in order to improve differentiation of wild-type from non-wild-type isolates (harbouring an acquired resistance). Clinical breakpoints should be a secondary comparator. This assessment will reveal whether genetic predictions could also be used to guide clinical decision making. Internationally agreed principles and quality control (QC) metrics will facilitate early harmonization of analytical approaches and interpretive criteria for WGS-based predictive AST. Only data sets that pass agreed QC metrics should be used in AST predictions. Minimum performance standards should exist and comparative accuracies across different WGS laboratories and processes should be measured. To facilitate comparisons, a single public database of all known resistance loci should be established, regularly updated and strictly curated using minimum standards for the inclusion of resistance loci. For most bacterial species the major limitations to widespread adoption for WGS-based AST in clinical laboratories remain the current high-cost and limited speed of inferring antimicrobial susceptibility from WGS data as well as the dependency on previous culture because analysis directly on specimens remains challenging. For most bacterial species there is currently insufficient evidence to support the use of WGS-inferred AST to guide clinical decision making. WGS-AST should be a funding priority if it is to become a rival to phenotypic AST. This report will be updated as the available evidence increases.
Subject(s)
Anti-Bacterial Agents/pharmacology , Bacteria/drug effects , Bacteria/genetics , Genome, Bacterial , Microbial Sensitivity Tests/methods , Europe , InternationalitySubject(s)
Bacterial Proteins/analysis , Drug Resistance, Bacterial , Gram-Negative Bacteria/enzymology , beta-Lactamases/analysis , Gram-Negative Bacteria/classification , Gram-Negative Bacteria/genetics , Gram-Negative Bacteria/isolation & purification , Gram-Negative Bacterial Infections/drug therapy , Gram-Negative Bacterial Infections/microbiology , Humans , Public Health Surveillance , United Kingdom , World Health OrganizationABSTRACT
Extra-intestinal pathogenic Escherichia coli are a significant cause of urinary tract infection and bacteraemia within the UK. We sought to identify the serogroups of 658 E. coli isolates collected in the UK between January 2011 and March 2012, to better understand the ExPEC population and understand the relevance of serogroups in this pathotype. Isolates were typed and serogroup identified using established phenotypic and molecular methods. Sixty-two serogroups were identified; 54 among urinary isolates and 35 among bloodstream isolates. However, serogroups O25, O6, and O2 dominated both infection types. These serogroups were linked to the major ExPEC STs as follows: ST131-O25, ST73-O6, ST127-O6, and ST95-O2. The serogroup data from this study have increased our understanding of the ExPEC population in the UK, but also highlighted key ST-serogroup relationships within the major ExPEC clones. These data can be used to guide vaccine design and in the development of laboratory diagnostic tests targeting the ExPEC population.
Subject(s)
Bacterial Typing Techniques , Escherichia coli Infections/microbiology , Extraintestinal Pathogenic Escherichia coli/classification , Serogroup , Adolescent , Adult , Aged , Aged, 80 and over , Bacteremia/epidemiology , Bacteremia/microbiology , Child , Child, Preschool , Escherichia coli Infections/epidemiology , Extraintestinal Pathogenic Escherichia coli/isolation & purification , Female , Genotype , Humans , Infant , Male , Middle Aged , United Kingdom/epidemiology , Urinary Tract Infections/epidemiology , Urinary Tract Infections/microbiology , Young AdultABSTRACT
OBJECTIVES: The diazabicyclooctane ß-lactamase inhibitor OP0595 (RG6080) also acts as an antibiotic, targeting PBP2 in Enterobacteriaceae, but this activity is vulnerable to mutational resistance. We used WGS to investigate the basis of this resistance. METHODS: Twenty OP0595-selected mutants, comprising four derived from each of five different Escherichia coli strains, were sequenced on Illumina HiSeq. Reads from each mutant were mapped to the assembled genome of the corresponding parent. A variant-calling file generated with Samtools was parsed to determine genetic alterations. RESULTS: Besides OP0595, the mutants consistently showed decreased susceptibility to mecillinam, which likewise targets PBP2, and grew as stable round forms in the presence of subinhibitory concentrations of OP0595. Among the 20 mutants, 18 had alterations in genes encoding tRNA synthase and modification functions liable to induce expression of the RpoS sigma factor through activation of the stringent response or had mutations suppressing inactivators of RpoS or the stringent response signal-degrading enzyme, SpoT. TolB was inactivated in one mutant: this activates RcsBC regulation and was previously associated with mecillinam resistance. The mechanism of resistance remained unidentified in one mutant. Both the RpoS and RcsBC systems regulate genes of cell division, including ftsAQZ that can compensate for loss or inhibition of PBP2, allowing survival of the challenged bacteria as stable round forms, as seen. CONCLUSIONS: WGS identified the global stringent response signal, entailing induction of RpoS, as the main mediator of mutational resistance to OP0595 in E. coli.
Subject(s)
Amdinocillin/pharmacology , Anti-Bacterial Agents/pharmacology , Azabicyclo Compounds/pharmacology , Drug Resistance, Multiple, Bacterial/genetics , Escherichia coli Proteins/antagonists & inhibitors , Escherichia coli/drug effects , Gene Expression Regulation, Bacterial , Lactams/pharmacology , Penicillin-Binding Proteins/antagonists & inhibitors , Amdinocillin/metabolism , Azabicyclo Compounds/metabolism , Bacterial Proteins/genetics , Escherichia coli/cytology , Escherichia coli/genetics , Escherichia coli/metabolism , Genetic Variation , Genome, Bacterial , High-Throughput Nucleotide Sequencing , Lactams/metabolism , Microscopy, Electron, Transmission , Mutation , Sigma Factor/genetics , beta-Lactamase Inhibitors/metabolism , beta-Lactamase Inhibitors/pharmacologyABSTRACT
OBJECTIVES: Escherichia coli is the most common agent of bacteraemia, bacterial gastroenteritis and urinary tract infections (UTIs). Lineages causing UTIs and gastrointestinal disease are well defined, but less is known about those causing bacteraemia. We therefore investigated the population structure of E. coli from bacteraemia in the UK and Ireland between 2001 and 2010. METHODS: E. coli isolates (nâ=â2166) were submitted to the BSAC Bacteraemia Surveillance Programme from 18 UK and Irish centres from 2001 to 2010. Genotypes were analysed by MLST using the Achtman scheme; MICs, blaCTX-M group and patient demographics were previously determined in the BSAC surveillance. RESULTS: Four hundred and forty-eight STs were identified, but five of these, and their associated clonal complexes (CCs), accounted for 58.4% (1264 of 2166) of isolates: CC73 was the most common (20.7%), followed by CC131 (13.9%), CC95 (11.3%), CC69 (6.9%) and CC12 (5.5%). All these, except CC69 (group D), belong to phylogenetic group B2. CC131 isolates were much more often MDR than other STs were: they rose from 2.9% of isolates in 2001 to 20.5%-20.7% in 2007-08 and then declined to 14.3% in 2010. Resistance rates to cephalosporins, aminoglycosides and fluoroquinolones remained below 10% in other major CCs throughout. CONCLUSIONS: The five most prevalent bacteraemia STs have all been associated previously with UTIs. They dominated in all years, but their proportions fluctuated, most notably for ST131, a globally disseminated high-risk clone that is often MDR.