Multicentre evaluation of the Check-Direct CPE® assay for direct screening of carbapenemase-producing Enterobacteriaceae from rectal swabs.

OBJECTIVES: The objective of this study was to evaluate in a multicentre survey the analytical performance of the Check-Direct CPE® assay (CDCPE), a multiplex PCR assay for the detection of carbapenemase-producing Enterobacteriaceae (CPE), directly from rectal swabs. METHODS: Adult patients admitted to a high-risk unit in four participating centres were prospectively screened for CPE carriage by rectal swabbing. Samples were cultured on chromogenic CPE-selective media in the local laboratories. All growing Enterobacteriaceae strains were transferred for confirmation of carbapenemase production by multiplex PCR, together with the faecal swabs for CDCPE, to the coordinating laboratory. RESULTS: Overall, 38 of the 394 samples analysed (9.6%; range 3%-20% per centre) yielded a positive signal for a carbapenemase gene with CDCPE, including 17 samples (4.3%; range 0%-15% per centre) that grew a total of 25 CPE-confirmed isolates (all OXA-48-like producers, including one isolate that simultaneously harboured a VIM-type carbapenemase). No CPE culture-positive samples were missed by CDCPE. Among the 21 samples that were CPE-positive with CDCPE but negative on culture, five were collected from previously known CPE carriers and 6/9 OXA-48-positive signals were detected at one participating centre that was undergoing a hospital-wide outbreak of OXA-48 CPE. When compared with the selective culture, the sensitivity and specificity of CDCPE were 100% and 94%, respectively. CONCLUSIONS: This study showed the value of CDCPE as a tool for screening CPE carriage in an epidemiological setting with a high prevalence of OXA-48 CPE. However, the potential added value for infection control management remains to be demonstrated.

Appropriateness of alert antibiotics measured by repeated prevalence surveys and impact of direct prescriber interaction and feedback.

OBJECTIVES: Hospital point prevalence surveys (PPS) are shown to help identifying determinants for inappropriate antimicrobial therapy (AMT) and create feedback opportunities to optimize AMT. METHODS: PPS were performed at the AZNikolaas hospital, on four wards with high consumption rates of three alert antibiotics (AB) to judge their appropriateness. The impact of a multidisciplinary interaction between a medical microbiologist, a clinical pharmacist and the prescriber on inappropriate AMT, hospital costs and intravenous AMT days, was analyzed. RESULTS: During this survey, 7,39% of hospitalized patients in the selected wards received one or more of three alert antibiotics. Out of 78 prescriptions, 35.90% were judged appropriate, 39.74% inappropriate and 24.36% had insufficient data for judgment. Only the oncology ward was associated with more frequent appropriate use of alert AB. In case of an unknown infection focus or a catheter-related infection, the relative risk of inappropriate use was the highest. Multidisciplinary interaction improved inappropriate AMT in 59% of cases. It resulted in a 2478€ healthcare AMT cost saving and a reduction of 30 intravenous AMT days. CONCLUSIONS: This survey shows high consumption rates and a high rate of inappropriate use of three alert AB in the observed wards. It revealed the lack of a local guideline concerning treatment of neutropenic fever of unknown origin and the need for more diagnostic information in electronical medical records. The survey demonstrated that direct feedback on inappropriate AMT to clinicians can be of added value, cost-saving and reducing length of intravenous AMT days. However, more studies are needed to confirm this.

Quality of MALDI-TOF mass spectra in routine diagnostics: results from an international external quality assessment including 36 laboratories from 12 countries using 47 challenging bacterial strains.

OBJECTIVES: Matrix assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) is a widely used method for bacterial species identification. Incomplete databases and mass spectral quality (MSQ) still represent major challenges. Important proxies for MSQ are the number of detected marker masses, reproducibility, and measurement precision. We aimed to assess MSQs across diagnostic laboratories and the potential of simple workflow adaptations to improve it. METHODS: For baseline MSQ assessment, 47 diverse bacterial strains, which are challenging to identify by MALDI-TOF MS, were routinely measured in 36 laboratories from 12 countries, and well-defined MSQ features were used. After an intervention consisting of detailed reported feedback and instructions on how to acquire MALDI-TOF mass spectra, measurements were repeated and MSQs were compared. RESULTS: At baseline, we observed heterogeneous MSQ between the devices, considering the median number of marker masses detected (range = [2-25]), reproducibility between technical replicates (range = [55%-86%]), and measurement error (range = [147 parts per million (ppm)-588 ppm]). As a general trend, the spectral quality was improved after the intervention for devices, which yielded low MSQs in the baseline assessment as follows: for four out of five devices with a high measurement error, the measurement precision was improved (p-values <0.001, paired Wilcoxon test); for six out of ten devices, which detected a low number of marker masses, the number of detected marker masses increased (p-values <0.001, paired Wilcoxon test). DISCUSSION: We have identified simple workflow adaptations, which, to some extent, improve MSQ of poorly performing devices and should be considered by laboratories yielding a low MSQ. Improving MALDI-TOF MSQ in routine diagnostics is essential for increasing the resolution of bacterial identification by MALDI-TOF MS, which is dependent on the reproducible detection of marker masses. The heterogeneity identified in this external quality assessment (EQA) requires further study.

Impact of solid cancer on in-hospital mortality overall and among different subgroups of patients with COVID-19: a nationwide, population-based analysis.

BACKGROUND: Cancer seems to have an independent adverse prognostic effect on COVID-19-related mortality, but uncertainty exists regarding its effect across different patient subgroups. We report a population-based analysis of patients hospitalised with COVID-19 with prior or current solid cancer versus those without cancer. METHODS: We analysed data of adult patients registered until 24 May 2020 in the Belgian nationwide database of Sciensano. The primary objective was in-hospital mortality within 30 days of COVID-19 diagnosis among patients with solid cancer versus patients without cancer. Severe event occurrence, a composite of intensive care unit admission, invasive ventilation and/or death, was a secondary objective. These endpoints were analysed across different patient subgroups. Multivariable logistic regression models were used to analyse the association between cancer and clinical characteristics (baseline analysis) and the effect of cancer on in-hospital mortality and on severe event occurrence, adjusting for clinical characteristics (in-hospital analysis). RESULTS: A total of 13 594 patients (of whom 1187 with solid cancer (8.7%)) were evaluable for the baseline analysis and 10 486 (892 with solid cancer (8.5%)) for the in-hospital analysis. Patients with cancer were older and presented with less symptoms/signs and lung imaging alterations. The 30-day in-hospital mortality was higher in patients with solid cancer compared with patients without cancer (31.7% vs 20.0%, respectively; adjusted OR (aOR) 1.34; 95% CI 1.13 to 1.58). The aOR was 3.84 (95% CI 1.94 to 7.59) among younger patients (<60 years) and 2.27 (95% CI 1.41 to 3.64) among patients without other comorbidities. Severe event occurrence was similar in both groups (36.7% vs 28.8%; aOR 1.10; 95% CI 0.95 to 1.29). CONCLUSIONS: This population-based analysis demonstrates that solid cancer is an independent adverse prognostic factor for in-hospital mortality among patients with COVID-19. This adverse effect was more pronounced among younger patients and those without other comorbidities. Patients with solid cancer should be prioritised in vaccination campaigns and in tailored containment measurements.

Towards a phenotypic screening strategy for emerging ß-lactamases in Gram-negative bacilli.

The purpose of this manuscript was to review recent literature and guidelines regarding phenotypic detection of emerging ß-lactamases [extended-spectrum ß-lactamases (ESBLs), AmpC ß-lactamases and carbapenemases] in Gram-negative bacilli (GNB) in order to formulate recommendations on best practice to screen for them. We conclude that chromogenic ESBL screening agar plates are suitable to screen for ESBL-producing Enterobacteriaceae directly from clinical samples. Furthermore, ceftazidime (CAZ) and ceftriaxone or cefotaxime (CTX) are the indicator antimicrobial agents of choice for ESBL detection in GNB. In non-inducible Enterobacteriaceae, the combined double-disk synergy test (CDDST) with at least CTX and CAZ and additionally cefepime as indicators is the preferred ESBL confirmation assay. The two most suitable ESBL confirmation strategies in AmpC co-producing Enterobacteriaceae are adapted CDDSTs: (i) with addition of 3-aminophenylboronic acid to CTX and CAZ disks; and (ii) with addition of cloxacillin (CLOX) to Mueller-Hinton agar. Reduced cefoxitin susceptibility and decreased susceptibility to cefotetan are regarded as suitable screening tests for plasmid-mediated and derepressed AmpC production. A CLOX-based CDDST with CTX and CAZ as indicators is considered to be the best AmpC confirmation assay. Finally, in Enterobacteriaceae isolates we suggest to screen for carbapenemases with a 0.5 µg/mL meropenem screening breakpoint. For class A carbapenemase confirmation, the home-prepared as well as the commercially available boronic acid-based CDDST can be considered. For metallo-ß-lactamase confirmation, ethylene diamine tetra-acetic-acid-based home-prepared assays are recommended. The most suitable method (CDDST or DDST) and indicator antimicrobial agent(s) vary depending on the bacterial genus.

Evaluation of 3 different agar media for rapid detection of extended-spectrum ß-lactamase-producing Enterobacteriaceae from surveillance samples.

Rapid detection of extended-spectrum ß-lactamase (ESBL)-producing Gram-negative bacilli in surveillance samples of high-risk patients allows early optimization of antimicrobial therapy and timely introduction of infection control procedures. This study evaluated the BLSE (AES Chemunex), chromID ESBL (bioMérieux), and Brilliance ESBL agar (Oxoid) for rapid detection of ESBL-producing Enterobacteriaceae from surveillance samples. A total of 139 perineal and nose samples were processed. Isolated bacterial strains were identified by mass spectrometry. ESBL confirmation was performed by phenotypical and molecular tests. Overall, 16 ESBL-producing Enterobacteriaceae were recovered. The sensitivities after 24 h of incubation were comparable (BLSE, 87.5%; Brilliance ESBL, 87.5%; and chromID, 81.3%). The specificity of chromogenic media (80.7-82.1%) was significantly higher compared to BLSE (60.8%). All 3 media are reliable to screen for ESBL-producing Enterobacteriaceae from surveillance samples. Yet, the main advantages of chromogenic media over BLSE reside in their chromogenic character and higher specificity, reducing the total number of isolates that require further identification and ESBL confirmation testing.

The preanalytical optimization of blood cultures: a review and the clinical importance of benchmarking in 5 Belgian hospitals.

Bloodstream infections remain a major challenge in medicine. Optimal detection of pathogens is only possible if the quality of preanalytical factors is thoroughly controlled. Since the laboratory is responsible for this preanalytical phase, the quality control of critical factors should be integrated in its quality control program. The numerous recommendations regarding blood culture collection contain controversies. Only an unambiguous guideline permits standardization and interlaboratory quality control. We present an evidence-based concise guideline of critical preanalytical determinants for blood culture collection and summarize key performance indicators with their concomitant target values. In an attempt to benchmark, we compared the true-positive rate, contamination rate, and collected blood volume of blood culture bottles in 5 Belgian hospital laboratories. The true-positive blood culture rate fell within previously defined acceptation criteria by Baron et al. (2005) in all 5 hospitals, whereas the contamination rate exceeded the target value in 4 locations. Most unexpected, in each of the 5 laboratories, more than one third of the blood culture bottles were incorrectly filled, irrespective of the manufacturer of the blood culture vials. As a consequence of this shortcoming, one manufacturer recently developed an automatic blood volume monitoring system. In conclusion, clear recommendations for standardized blood culture collection combined with quality control of critical factors of the preanalytical phase are essential for diagnostic blood culture improvement.