European Journal of Clinical Microbiology & Infectious Diseases最新文献

This study aimed to evaluate the in vitro activity of sulbactam-durlobactam (SUL-DUR), a novel β-lactam/β-lactamase inhibitor combination, against carbapenem-resistant Acinetobacter baumannii (CRAB) clinical isolates from a tertiary care facility in north India. Special focus was placed on extensively drug-resistant (XDR) strains, a subgroup which is likely to be underrepresented in global surveillance.A total of 100 non-duplicate CRAB clinical isolates were included in the study. Isolates were obtained from various clinical specimens, primarily respiratory samples, and characterized using MALDI-TOF MS. Susceptibility testing for SUL-DUR was performed using both broth microdilution (BMD) and disk diffusion (DD) in accordance with CLSI M100, 35th edition guidelines. Quality control was ensured using A. baumannii NCTC 13304 strain. Descriptive analysis and categorical interpretations were employed to evaluate susceptibility patterns. Of the 100 CRAB isolates, 80% were classified as XDR. Overall, 52% of isolates were susceptible to SUL-DUR, 46% resistant, and 2% intermediate. Among XDR strains, susceptibility dropped to 40%. Respiratory isolates, particularly from endotracheal aspirates and bronchoalveolar lavage, exhibited higher resistance rates. All non-XDR isolates (n=20) were susceptible to SUL-DUR. BMD and DD methods showed 100% categorical agreement. The MIC distribution ranged from≤0.25 to ≥128 µg/mL.SUL-DUR showed promising in vitro activity against CRAB, but with reduced efficacy in XDR strains, particularly respiratory isolates. High concordance between BMD and DD supports the utility of disk diffusion in resource-limited settings.

Purpose: Rapid identification (ID) and antibiotic susceptibility testing are vital for the treatment of bloodstream infections (BSIs). The aim of this study was to perform direct identification and rapid antimicrobial susceptibility testing (RAST), from positive blood cultures and to compare the performance of these rapid methods with standard reference methods.

Methods: Blood cultures (BC) submitted to Marmara University Pendik Training and Research Hospital Clinical Microbiology Laboratory between September 2022 - April 2023, that yielded positive signal and were determined to be monomicrobial by gram staining were selected randomly. ID was performed using MALDI-TOF MS(bioMérieux, France). Based on these results, rapid antimicrobial susceptibility testing (RAST) was applied to 103 bottles that met RAST eligibility criteria. The results of rapid ID and RAST were evaluated by comparing them with the results obtained from colony-grown isolates.

Results: Rapid ID showed that out of 306 bottles, 281 (91.8%) were monomicrobial. High rates of correct identification were achieved for gram-negative bacilli (84.3%), gram-positive chain cocci (79.4%), and gram-positive cluster cocci (55.2%), while performance was lower for gram-positive bacilli (27.3%) and yeasts (37.5%). For RAST, the readability of inhibition zone diameters increased progressively with incubation time, reaching 85.2%, 94.5%, 100%, and 100% at 4, 6, 8, and 16-20 h, respectively. The categorical agreement of the test remained consistently high across all time points, measuring 98.35% at 4 h, 98.49% at 6 h, 98.38% at 8 h, and 98.84% at 16-20 h.

Conclusion: Rapid ID of microorganisms directly from positive BC bottles, combined with RAST based on EUCAST RAST criteria, demonstrates high accuracy and reliability compared to conventional methods. These rapid approaches significantly reduce the turnaround time for both identification and susceptibility results-by approximately 16-20 h and 32-48 h, respectively thereby enabling earlier targeted antimicrobial therapy and improving clinical management of BSIs.

Background: Non-tuberculous mycobacteria (NTM) are of increasing clinical importance, yet their identification remains challenging. While matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) offers a rapid, high-throughput solution, its diagnostic accuracy for NTM has not been fully established.

Methods: A comprehensive systematic review and meta-analysis published between 2011 and May 2024 were conducted. Studies evaluating the diagnostic accuracy of MALDI-TOF MS for NTM species identification against reference standards were included. Pooled identification rates were calculated via a random effects model. Subgroup analyses were used to assess the influence of variables such as growth rate, culture media, and instrument platform. Quality assessment was performed via the Joanna Briggs Institute checklist.

Results: Across 55 studies, MALDI-TOF MS achieved a pooled identification accuracy of 88% (95% CI: 84-91%) for clinical NTM isolates. Subgroup analyses revealed greater accuracy for rapidly growing mycobacteria (93%) than for slowly growing mycobacteria (89%). Compared with liquid (85%) or co-culture (84%) systems, cultures on solid media yielded superior results (91%). The Bruker MALDI Biotyper and bioMérieux VITEK MS platforms showed comparable performance, although species-level accuracy varied. Notably, species such as M. fortuitum, M. smegmatis, and M. marinum were identified with high precision (> 95%), whereas species such as M. colombiense and M. parascrofulaceum exhibited poor discrimination.

Conclusion: MALDI-TOF MS is highly accurate in identifying clinically relevant NTM, particularly rapidly growing species. Despite improvements in databases and sample preparation, distinguishing closely related or rare species remains challenging, underscoring the need for further optimization and standardization.

CTX-M enzymes account for more than 90% of all extended-spectrum β-lactamases (ESBLs) identified in Enterobacterales. Therefore, rapid identification of these enzymes could improve clinical outcomes in patients infected or colonized by such pathogens. In this review, we described the characteristics and limitations of commercially available rapid tests for detecting CTX-M proteins (lateral flow immunoassays) or bla_CTX-M genes (microarrays, quantitative PCR, or loop-mediated isothermal amplification). Additionally, we summarized and discussed their potential clinical impact. Some commercial CTX-M assays - particularly those analyzing aliquots from positive blood cultures (i.e., Verigene, BioFire FilmArray, ePlex) - demonstrated clear advantages over standard-of-care methods, shortening the interval to effective therapy and improving overall patient outcomes. However, the widespread adoption of these rapid assays in routine laboratories remains limited due to several factors, including high costs and the lack of robust evidence supporting their positive impact. To address these implementation challenges, laboratories should focus on a defined patient subgroup in whom the application of these assays is likely to yield the greatest clinical impact. In particular, we propose that all laboratories at least perform rapid CTX-M assays on all Gram-negative-positive blood cultures (including those with sterile fluids) obtained from critically ill patients, such as ICU-patients with septic shock. This strategy is best when accompanied by active communication between the laboratory and key stakeholders in patient management. Providing rapid results for this subpopulation of patients may facilitate timely initiation of appropriate therapy and ultimately improve patient outcomes.

Background: Laboratory testing plays an important role in diagnosis and clinical management of Lyme borreliosis (LB). While external quality assessments (EQAs) evaluate the technical quality of laboratory diagnostics, the clinical interpretation of laboratory results often remains unassessed. Although specific guidelines are available, different interpretation can result in variations in clinical diagnosis and subsequent management of LB patients. This study aimed to evaluate variations in interpretating LB laboratory diagnostics in relation to the clinical history of the patient.

Methods: An EQA was organized for medical microbiological laboratories (MMLs) in the Netherlands using a web-based survey. The survey consisted of twenty LB case descriptions including laboratory findings. Participants were asked to (i) interpret each case according to their protocols (open-ended), and (ii) rate the likelihood of the case being active LB (multiple-choice). Six LB diagnostics experts determined the baseline and scored participants' answers on a 1-10 scale.

Results: Of the 50 invited MMLs, 38 (76.0%) completed the survey. The overall mean score was 8.8 (range: 7.2 - 9.8). For the multiple-choice questions, the mean score was 9.6 (range: 8.4 - 10) and for open-ended questions this was 8.0 (range: 5.6 - 9.6). Lower scores were obtained for low-incidence manifestations.

Conclusions: This EQA showed that interpreting LB laboratory results in relation to the clinical information was good and increased awareness among participants to challenges of LB diagnosis and treatment. Training and education could improve interpretation skills. This EQA might be exemplary for future harmonization efforts for (pan-European) clinical evaluation of LB diagnostics. As a potential future approach, supplementing guidelines with an artificial intelligence-based clinical support system could aid medical microbiologists and physicians in decision making, especially for rare manifestations.

Purpose: The identification of filamentous fungi in clinical microbiology laboratories remains a challenging task. Although matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) has revolutionized microbial diagnostics by enabling rapid and accurate species-level identification, its application to molds is still evolving. This study aims to evaluate the performance of two Bruker MALDI-TOF MS systems, Sirius One and Microflex 3.1, for the identification of filamentous fungi using different extraction protocols and database configurations.

Method: A total of 68 filamentous fungal isolates, including clinically significant species, were analyzed. Fungal cultures were processed under standardized conditions using two protein extraction methods: a detailed in-tube extraction with ethanol, formic acid, and acetonitrile, and a direct on-plate extraction. Spectra were acquired using both Sirius One and Microflex 3.1 systems, and identifications were performed using manufacturer-provided databases and the MSI-2.0 database.

Results: The Sirius One system outperformed Microflex 3.1, achieving a 92.6% correct identification rate with the MSI-2 database compared to 70.6% for Microflex (p < 0.01). When using manufacturer-provided databases, identification rates were lower: 51.5% for Sirius One and 41.2% for Microflex. Notably, the on-plate extraction method performed comparably to the in-tube method, achieving 94.1% accuracy with Sirius One and the MSI-2 database.

Conclusion: The combination of the Sirius One system, MSI-2.0 database, and on-plate extraction method provides a highly effective and time-efficient workflow for the identification of filamentous fungi in routine clinical diagnostics, reaching 94.1% accuracy. This approach is recommended for implementation in clinical mycology laboratories, though further optimization of manufacturer-supplied databases remains necessary.

Purpose: This study aimed to determine the prevalence of Staphylococcus aureus small colony variants (SCV) in people with cystic fibrosis (pwCF), evaluate the clinical differences of single versus multiple detections of SCVs in respiratory cultures, and assess antibiotic resistance.

Methods: This monocentric retrospective study included pwCF colonised by S. aureus SCVs between January 1, 2017, and December 31, 2023, at the CF centre of Florence, Italy. Clinical data were collected, and patients with single versus recurrent SCV detections were compared to identify risk factors for recurrent SCVs.

Results: Among 154 pwCF (62 children, 92 adults), SCV was detected in 38.31%. Univariate analysis identified lower percent predicted forced expiratory volume in the first second (ppFEV₁) (OR: 0.49, p = 0.04), prior trimethoprim-sulfamethoxazole (TMP-SMX) use (OR: 2.639, p = 0.005), chronic azithromycin (OR: 2.228, p = 0.020), and chronic/intermittent Pseudomonas aeruginosa colonisation (OR: 2.107, p = 0.049) as risk factors for recurrent SCVs. In multivariate analysis, prior TMP-SMX use was the sole independent risk factor for recurrent SCVs (OR: 2.280, p = 0.028). A significant decline in respiratory function over time (p = 0.025) was observed in patients with recurrent SCVs, but not in those with a single SCV episode. Resistance to TMP-SMX was observed in nearly all isolates tested (231/234) with available antibiotic susceptibility testing results. SCV detection frequency decreased over the study period (19.06% in 2017 vs. 5.83% in 2023, p < 0.00001), probably due to the increased use of elexacaftor-tezaxaftor-ivacaftor.

Conclusions: S. aureus SCVs were highly prevalent in pwCF, although their frequency declined over time with the widespread use of elexacaftor-tezacaftor-ivacaftor. Recurrent SCV detections, but not single episodes, were associated with a progressive decline in respiratory function. Prior TMP-SMX exposure was identified as an independent risk factor for recurrent SCV detections. The clinical implications of these findings require further investigation to clarify causality and guide management strategies.

The human-oral associated Capnocytophaga species are low-grade pathogens, more commonly affecting immunocompromised patients. Bloodstream infections are the most common clinical presentation. Microbiological diagnosis and antibiotic susceptibility testing are challenging due to the hard-to-growth character of these species, which complicates the initiation of effective antibiotic therapy. We present the case of an immunocompromised 60-year-old female receiving cefepime who developed febrile neutropenia. Blood cultures remained positive for a Capnocytophaga gingivalis isolate producing the CSP-1 extended-spectrum-β-lactamase (ESBL). This is the first description of CSP-1 in a non-C. sputigena species. Immune reconstitution led to clinical resolution.

Treating carbapenem-resistant Enterobacterales, mainly those producing metallo-β-lactamases (MBL) is a subject of major concern. The combination aztreonam-avibactam (AZA) was developed in an attempt to overcome this challenge, as avibactam inhibits KPC and other serine-β-lactamases, enabling aztreonam (ATM) to act against MBL. However, in scenarios where AZA is not licensed so far, the combination of ATM with ceftazidime-avibactam (CZA) is an alternative that has been proved in vivo efficacy and in vitro synergic activity. We propose the TurbiTest, an alternative method based on turbidity measurement of bacterial growth after a short incubation period (4 h) in the presence and absence of antibiotics to easily determine susceptibility to this combination. A total of 134 Enterobacterales harboring a variety of resistance genes (52 bla_KPC, 53 bla_NDM, 26 bla_KPC + bla_NDM, 2 bla_NDM + bla_OXA-48-like, 1 bla_OXA-48-like) as well as 11 Enterobacterales negative for carbapenemase genes by HRM-qPCR were evaluated for susceptibility to CZA, ATM, ATM-CZA and AZA. According to broth microdilution (BMD), 55.9% were resistant to CZA and 69.7% to ATM. All isolates were susceptible to ATM-CZA and AZA. Compared to BMD, TurbiTest from colonies (TTc) presented categorical agreement (CA) of 95.9% for CZA, 97.9% for ATM and ATM-CZA, and 99.3% for AZA. Fifty-eight spiked blood cultures were evaluated, with CA of 98.3% for CZA and ATM, and 100% for ATM-CZA and AZA. Besides, 41 clinical, consecutive Enterobacterales-positive blood cultures were tested (TTbc), with 100% of CA for CZA, 95.1% for ATM and 92.7% for ATM-CZA and AZA. TurbiTest is an inexpensive test that demonstrated a promising performance with considerably reduced turnaround time to results (less than 5 h). Interlaboratory reproducibility, as well as the performance with other bacterial population remain to be explored.