ABSTRACT
In recent years, the diagnosis of bloodstream infections has been complemented by rapid microbiological methods, unattainable to most clinical laboratories in resource-limited settings. We evaluated the impact of their shortage on antibiotic therapy adequacy. We conducted a prospective multicenter cohort study including 150 adult Gram-negative bacilli bacteremia episodes, evenly distributed across three university hospitals: one in Lebanon, a resource-limited setting, and two in France, a resource-rich setting. Previous colonization by multidrug-resistant organisms (MDRO) was significantly more prevalent among the Lebanese than the French group of patients (16/50 vs. 5/100; p < 0.01). Bloodstream infections by carbapenemase-producing Enterobacterales and other MDRO were higher among the Lebanese than the French group of patients (25/50 vs. 12/100; p < 0.01). For the French group, rapid identification of species and mechanisms of resistance significantly shortened turnaround time for definitive laboratory diagnosis and increased antibiotic therapy adequacy. No statistically significant differences were noted in targeted antibiotic therapy between the two groups. This study suggests that, in settings where bacterial resistance is prevalent, rapid microbiological methods have not provided any additional value. The clinical and economic impact of rapid microbiological methods will likely depend on local CPE, VRE, and other MDRO epidemiology and are areas for future research.
ABSTRACT
Introduction: SARS-CoV-2 serology have several indications. Currently, as there are various types available, it is important to master their performance in order to choose the best test for the indication. We evaluated and compared four different commercial serology tests, three of them had the Food and Drug Administration Emergency Use Authorization (FDA-EUA). Our goal was to provide new data to help guide the interpretation and the choice of the serological tests. Methods: Four commercial tests were studied: Elecsys® Roche® on Cobas® (total anti-nucleocapsid (N) antibodies), VIDAS® Biomerieux® (IgM and IgG anti- receptor binding domain (RBD) antibodies), Mindray® (IgM and IgG anti-N and anti-RBD antibodies) and Access® Beckman Coulter® (IgG anti-RBD antibodies). Two panels were tested: a positive panel (n = 72 sera) obtained from COVID-19-confirmed patients with no vaccination history and a negative panel (n = 119) of pre-pandemic sera. The analytical performances were evaluated and the ROC curve was drawn to assess the manufacturer's cut-off for each test. Results: A large range of variability between the tests was found. The Mindray®IgG and Cobas® tests showed the best overall sensitivity, which was equal to 79.2% CI 95% (67.9−87.8). The Cobas® test showed the best sensitivity after 14 days of COVID-19 molecular confirmation; which was equal to 85.4% CI 95% (72.2−93.9). The Access® test had a lower sensitivity, even after day 14 (55.5% CI 95% (43.4−67.3)). The best specificity was noted for the Cobas®, VIDAS®IgG and Access® IgG tests (100% CI 95% (96.9−100)). The IgM tests, VIDAS®IgM and Mindray®IgM, showed the lowest specificity and sensitivity rates. Overall, only 43 out of 72 sera (59.7%) showed concordant results by all tests. Retained cut-offs for a significantly better sensitivity and accuracy, without significant change in the specificity, were: 0.87 for Vidas®IgM (p = 0.01) and 0.14 for Access® (p < 10−4). The combination of Cobas® with Vidas® IgM and IgG offered the best accuracy in comparison with all other tests combinations. Conclusion: Although using an FDA-EUA approved serology test, each laboratory should carry out its own evaluation. Tests variability may raise some concerns that seroprevalence studies may vary significantly based on the used serology test.
