Optimal detection of carbapenemase-producing Enterobacteriaceae from rectal samples: a role for enrichment?

BACKGROUND: Successful laboratory detection of carbapenemase-producing Enterobacteriaceae (CPE) in patient surveillance samples is a diagnostic challenge. In the absence of a reference standard for screening rectal swabs for CPE, many phenotypic, genotypic, culture- and non-culture-based assays have been proposed for identifying these bacteria. AIM: To develop and optimize a CPE screening protocol capable of identifying all frequently encountered CPE, including those producing OXA-48-like carbapenemases. METHODS: Faropenem susceptibility testing was performed on 507 presumptive CPE isolated from diagnostic samples and CPE rectal screens between March and August 2016. Results from this CPE screening method were compared to those from direct culture on mSuperCARBA™, temocillin enrichment culture, and use of an antibiotic resistance algorithm, to determine the optimal method to employ in the detection of CPE. FINDINGS: Faropenem was a poor predictor of carbapenemase production (58% true positives). The combination of a temocillin enrichment stage and interpretive reading of antibiotic resistance phenotypes improved the recovery and identification of CPE significantly (91% true positives), especially for OXA-48 producers (P = 0.03). CONCLUSION: The combination of temocillin enrichment, a selective chromogenic medium, and an antibiotic resistance-based algorithm significantly improved the detection of all CPE recovered from routine and targeted surveillance samples

Trends in ExPEC serogroups in the UK and their significance

We thank the British Society for Antimicrobial Chemotherapy for kindly providing E. coli bloodstream isolates from the BSAC Bacteraemia Resistance Surveillance Programme (2011), and all the staff at PHE’s Gastrointestinal Bacteria Reference Unit for their guidance and patience during the serogrouping process. This work was performed as part of a PhD study funded by PHE

Prevalence of carbapenem resistance and carbapenemase production among Enterobacteriaceae isolated from urine in the UK: results of the UK infection-Carbapenem Resistance Evaluation Surveillance Trial (iCREST-UK)

AstraZenec

The influence of red worms (E. Foetida) on compost’s fertilizing properties

Composting is becoming a more and more common way of biodegradable waste disposal. Composts should be characterized by high content of nutrients and low amount of pollutants. Vermicompost is a compost produced by overpopulated culture of earthworm Eisenia foetida (Savigny 1826). World scientific literature states that vermicompost has a high fertilizing value which often exceeds such value of conventional composts. The results showed that vermicompost has a much higher fertilizing value than the compost produced by the traditional pile method. However, prism vermicompost created with the participation of a less concentrated population of earthworms has an intermediate value as a fertilizer (nitrogen and heavy metals), it could be assessed as a lower value product due to the lower content of potassium and phosphorus than the material obtained without earthworms

Community prevalence of carbapenemase-producing organisms in East London

Background: Over the last decade there has been a rapid, worldwide increase in carbapenem resistance, which is of growing concern. The main protagonists, the carbapenemases Klebsiella pneumoniae carbapenemase (KPC), oxacillinase β-lactamase 48 (OXA-48), imipenemase metallo-β-lactamase (IMP), Verona integron-borne metallo-β-lactamase (VIM), and New Delhi metallo-β-lactamase (NDM) have also been reported across the UK. However, these reports are derived from a combination of reactive screening, outbreak control, inpatient surveillance, and diagnostic samples. Therefore, the true community prevalence is unknown. Aim: To determine the community prevalence of carbapenemase-producing organisms (CPOs) in the area served by Barts Health NHS Trust. Methods: Active screening of 200 non-duplicate community stool samples was performed. Patient demographics and foreign travel history were extracted from the laboratory information management system to identify potential risk factors for carriage of CPOs. Findings: Patients in this study were aged from one to 93 years and were evenly distributed between male and female. Foreign travel in the last year was listed for 46 out of 200 (23%) patients, with the most commonly visited countries including Bangladesh (4%), India (2.5%), Morocco (2%), and Turkey (1.5%). However, only one patient tested positive for a CPO, an NDM-producing Pseudomonas aeruginosa, and this patient had travelled to the Caribbean. Conclusion: To date, there have been no studies investigating the prevalence of CPOs in the UK community. Given the high-risk patient population served by Barts Health NHS Trust, it is reassuring that the prevalence observed here was low. However, it should be highlighted that travel to countries not previously categorized as high risk may also pose a threat

A point prevalence study to determine the inpatient rate of carbapenemase-producing organisms at a large London NHS Trust

SummaryBackgroundThere has been an increase in the number of carbapenemase-producing organisms documented across the UK over the past 10 years. From these, the ‘big five’ carbapenemases (KPC, OXA-48, IMP, VIM, and NDM) are the most common types reported in the order Enterobacterales, identified from a variety of reactive screening, outbreak, inpatient surveillance, and diagnostic samples.AimTo perform a point prevalence study to determine the inpatient carriage rate of carbapenemase-producing organisms at Barts Health NHS Trust, which encompasses 2.5 million patients across four London boroughs: Tower Hamlets, Newham, Redbridge, and Waltham Forest.MethodsRectal swabs were collected from consenting inpatients, alongside details of the ward’s medical specialty, patient’s country of birth, history of foreign travel, length of hospitalization, and history of prior hospitalization. Swabs were enriched and subcultured on to mSuperCARBA selective medium. All Enterobacterales, Acinetobacter, and Pseudomonas species were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy and underwent antibiotic susceptibility testing by disc diffusion, according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines. All isolates were screened for the ‘big five’ carbapenemases using a modified version of a published reverse transcriptase–polymerase chain reaction assay.FindingsOf the 977 inpatients tested, 35 CPOs were isolated from 30 patients. NDM was the most frequently detected carbapenemase, followed by OXA-48, with an overall prevalence of 3.1%. Organisms isolated included Klebsiella pneumoniae, Enterobacter cloacae, Proteus mirabilis, and Escherichia coli. Renal and elderly care patients had the highest prevalences of CPOs, whereas the intensive care unit prevalence was low. Statistical analysis found that hospitalization abroad, any previous hospitalization, foreign travel and, specifically, travel to India, Pakistan, and Bangladesh were associated with increased risk of CPO carriage.ConclusionThe overall prevalence of CPOs at Barts Health Trust was 3.1%, comprising NDM and OXA-48-type carbapenemases, which is in line with other London-based studies. Renal patients and the elderly had the highest burden of CPOs, whereas previous hospitalization and foreign travel were associated with an increased risk of CPO carriage

Comparative virulence of urinary and bloodstream isolates of extra-intestinal pathogenic Escherichia coli in a Galleria mellonella model

Extra-intestinal pathogenic Escherichia coli (ExPEC) are a significant cause of urinary tract infections and bacteraemia worldwide. Currently no single virulence factor or ExPEC lineage has been identified as the sole contributor to severe extra-intestinal infection and/or urosepsis. Galleria mellonella has recently been established as a simple model for studying the comparative virulence of ExPEC. In this study we investigated the virulence of 40 well-characterized ExPEC strains, in G. mellonella, by measuring mortality (larvae survival), immune recognition/response (melanin production) and cell damage (lactate dehydrogenase production). Although mortality was similar between urinary and bloodstream isolates, it was heightened for community-associated infections, complicated UTIs and urinary-source bacteraemia. Isolates of ST131 and those possessing afa/dra, ompT and serogroup O6 were also associated with heightened virulence

Comparative virulence of urinary and bloodstream isolates of extra-intestinal pathogenic Escherichia coli in a Galleria mellonella model

Extra-intestinal pathogenic Escherichia coli (ExPEC) are a significant cause of urinary tract infections and bacteraemia worldwide. Currently no single virulence factor or ExPEC lineage has been identified as the sole contributor to severe extra-intestinal infection and/or urosepsis. Galleria mellonella has recently been established as a simple model for studying the comparative virulence of ExPEC. In this study we investigated the virulence of 40 well-characterized ExPEC strains, in G. mellonella, by measuring mortality (larvae survival), immune recognition/response (melanin production) and cell damage (lactate dehydrogenase production). Although mortality was similar between urinary and bloodstream isolates, it was heightened for community-associated infections, complicated UTIs and urinary-source bacteraemia. Isolates of ST131 and those possessing afa/dra, ompT and serogroup O6 were also associated with heightened virulence