Improved blood culture workflow for faster identification of KPC-producing Enterobacterales

Rapid phenotypic testing for detection of carbapenemase- or extended-spectrum ß-lactamase-producing Enterobacterales directly from blood cultures: a systematic review and meta-analysis

BACKGROUND

Early identification of extended-spectrum ß-lactamase (ESBL) and carbapenemase-producing Enterobacterales (CP-CRE) is critical for timely therapy. Rapid phenotypic tests identifying these resistance mechanisms from pure bacterial colonies have been developed.

OBJECTIVES

To determine the operating characteristics of available rapid phenotypic tests when applied directly to positive blood cultures.

METHODS OF DATA SYNTHESIS

Bivariate random effects models were used unless convergence was not achieved where we used separate univariate models for sensitivity and specificity.

DATA SOURCES

MEDLINE, CENTRAL, Embase, BIOSIS, and Scopus from inception to 16 March 2021.

STUDY ELIGIBILITY CRITERIA

Studies using any rapid phenotypic assay for detection of ESBL or CP-CRE directly from blood cultures positive for Enterobacterales, including those utilizing spiked blood cultures. Case reports/series, posters, abstracts, review articles, those with ≤5 resistant isolates, and studies lacking data or without full text were excluded.

PARTICIPANTS

Consecutive patient samples (main analysis) or spiked blood cultures (sensitivity analysis).

TESTS

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry assays (MALDI-TOF) and commercially available chromogenic or immunogenic assays.

REFERENCE STANDARD

Conventional laboratory methods and/or polymerase chain reaction (PCR).

ASSESSMENT OF RISK OF BIAS

Quality Assessment of Diagnostic Accuracy Studies Version 2 (QUADAS-2).

RESULTS

For detection of the ESBL phenotype the respective pooled sensitivities and specificities for consecutive clinical samples were as follows: 94% (95% CI 93-99%) and 97% (95% CI 95-100%) for MALDI-TOF/mass spectrometry (n = 1); and 98% (95% CI 92-100%) and 100% (95% CI 96-100%) for chromogenic assays (n = 7). For the CP-CRE phenotype the respective pooled sensitivity and specificities for consecutive clinical samples were as follows: 100% (95% CI 99-100%) and 100% (95% CI 100-100%) for MALDI-TOF (n = 2); 96% (95% CI 77-99%) and 100% (95% CI 81-100%) for chromogenic assays (n = 4); and 98% (95% CI 96-100%) and 100% (95% CI 100-100%) for immunogenic testing (n = 2).

CONCLUSIONS

Rapid phenotypic assays that can be directly applied to positive blood cultures to detect ESBL and carbapenemase production from Enterobacterales exist and, although clinical studies are limited, they appear to have high sensitivity and specificity. Their potential to facilitate patient care through timely identification of bacterial resistance should be further explored.

A Rapid Carbapenemase Genes Detection Method with Xpert Carba-R from Positive Blood Cultures Compared with NG-Test Carba 5 and Sequencing

Objective

The objective of the current study was to evaluate the performance of Xpert Carba-R for the direct detection and identification of carbapenemase genes from positive blood cultures.

Methods

Pathogens which extracted from positive blood cultures and identified using MALDI-TOF MS as Enterobacterales were included in this study. Xpert Carba-R was used for the rapid detection of carbapenemase genes from positive blood cultures. NG-Test CARBA 5 and polymerase-chain reaction (PCR) sequencing were used for the detection of carbapenemases and carbapenemase genes in positive blood culture isolates, respectively. Finally, antibiotic susceptibility tests were conducted using the VITEK-2 Compact system.

Results

A total of 133 positive blood cultures of Enterobacterales were collected and 27 of them were detected to carry carbapenemase genes using Xpert Carba-R. In comparison with PCR sequencing results, the sensitivity and specificity of Xpert Carba-R and NG-Test CARBA 5 were calculated as 100%. Additionally, Xpert Carba-R could significantly shorten the turnaround time by directly detecting positive blood cultures comparing with NG-Test CARBA 5. For 27 carbapenem-producing strains, the resistance rates of carbapenems and aztreonam were 96.3% and 92.6%, respectively. Strains carrying the blaKPC gene were all sensitive to ceftazidime-avibactam. All strains were sensitive to tigecycline and colistin.

Conclusion

Xpert Carba-R is suitable for the rapid detection of main carbapenemase genes from positive blood cultures with high sensitivity and specificity. In comparison with NG-Test CARBA 5 and PCR sequencing methods, the timely and convenient method can be a useful test to guide optimal therapy and infection control.

Assessment of the Bacterial Pollution and Detection of Antibiotic Resistance Genes in Benin: Case of the Hydrographic Channel Complex Cotonou-Nokoué Lake

The study aims to document the level of contamination of the aquatic ecosystem of the Cotonou-Lake Nokoué canal hydrographic complex by multidrug-resistant bacteria and their resistance genes. For this purpose, water samples were taken from several points of the complex and from the sediments at the depth of the lake. Samples of several species of freshly caught fish products from the lake were also collected. Bacteriological analyses were carried out according to the AFNOR standard (NF U: 47–100). The identification of the different bacterial species isolated was then carried out using the API 20E gallery and specific biochemical tests. The antibiogram of the strains was performed according to the recommendations of the EUCAST. Molecular characterization of the identified strains was carried out by searching for resistance and virulence genes. The results obtained revealed the presence of several bacterial species in water samples and in sediment and intestine samples of fishery products with a predominance of Gram-negative bacilli. The resistance profile of Gram-negative bacilli showed a total resistance to metronidazole (100%). 23% of the strains were also resistant to ciprofloxacin, 41% to amoxicillin, and 60% to aztreonam. Of the Gram-positive cocci identified, 66% was resistant to vancomycin, 7.5% to ciprofloxacin, 71% to erythromycin, and 22% to tetracycline. Regarding the genes sought, bla_TEM (46%), bla_SHV (24%), and bla_CTX-M-15 (31%) were present in the genome of Gram-negative bacilli as resistance genes and fimH (41%) as virulence gene. As for Gram-positive cocci, the van B gene was completely absent. The van A was present at 6.25% in Staphylococcus aureus and mecA at 21.88 and 33.33%, respectively, in Staphylococcus aureus and coagulase-negative staphylococci strains. The high resistance of isolated bacterial strains is a matter of concern and calls for a rational use of antibiotics in order to avoid the transmission of antibiotic resistance from the environment to humans.