Evaluation of pneumococcal urinary antigen testing for respiratory tract infection investigations

Quantitatively detecting Candida albicans enolase1 with a one-step double monoclonal antibody sandwich ELISA assay

Invasive candidiasis (IC) is often a cause of severe concern for the hospitalized patients, particularly those who are critically sick. However management of this disease is challenging due to a lack of effective laboratory diagnostic techniques. Hence, we have developed a one-step double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) using a pair of specific monoclonal antibodies (mAbs) for the quantitative detection of Candida albicans enolase1 (CaEno1), which is considered as an important diagnostic biomarker for IC. The diagnostic efficiency of the DAS-ELISA was evaluated by using a rabbit model of systemic candidiasis and compared with other assays. The method validation results demonstrated that the developed method was sensitive, reliable, and feasible. The findings of the rabbit model plasma analysis indicated that the diagnostic efficiency of the CaEno1 detection assay was better in comparison to the (1,3)-β-D-glucan detection and blood culture. CaEno1 is present in the blood of infected rabbits for a brief period and at relatively low levels and thus the combination of CaEno1 antigen and IgG antibodies detection could aid to increase diagnostic efficiency. However, to improve the clinical application of CaEno1 detection in the future, efforts should be made to increase the detection limit of the test by promoting technical developments and by optimizing the protocol for the clinical serial determinations.

Effectiveness of Streptococcus Pneumoniae Urinary Antigen Testing in Decreasing Mortality of COVID-19 Co-Infected Patients: A Clinical Investigation

Background and objectives: Streptococcus pneumoniae urinary antigen (u-Ag) testing has recently gained attention in the early diagnosis of severe and critical acute respiratory syndrome coronavirus-2/pneumococcal co-infection. The aim of this study is to assess the effectiveness of Streptococcus pneumoniae u-Ag testing in coronavirus disease 2019 (COVID-19) patients, in order to assess whether pneumococcal co-infection is associated with different mortality rate and hospital stay in these patients. Materials and Methods: Charts, protocols, mortality, and hospitalization data of a consecutive series of COVID-19 patients admitted to a tertiary hospital in northern Italy during COVID-19 outbreak were retrospectively reviewed. All patients underwent Streptococcus pneumoniae u-Ag testing to detect an underlying pneumococcal co-infection. Covid19+/u-Ag+ and Covid19+/u-Ag- patients were compared in terms of overall survival and length of hospital stay using chi-square test and survival analysis. Results: Out of 575 patients with documented pneumonia, 13% screened positive for the u-Ag test. All u-Ag+ patients underwent treatment with Ceftriaxone and Azithromycin or Levofloxacin. Lopinavir/Ritonavir or Darunavir/Cobicistat were added in 44 patients, and hydroxychloroquine and low-molecular-weight heparin (LMWH) in 47 and 33 patients, respectively. All u-Ag+ patients were hospitalized. Mortality was 15.4% and 25.9% in u-Ag+ and u-Ag- patients, respectively (p = 0.09). Survival analysis showed a better prognosis, albeit not significant, in u-Ag+ patients. Median hospital stay did not differ among groups (10 vs. 9 days, p = 0.71). Conclusions: The routine use of Streptococcus pneumoniae u-Ag testing helped to better target antibiotic therapy with a final trend of reduction in mortality of u-Ag+ COVID-19 patients having a concomitant pneumococcal infection. Randomized trials on larger cohorts are necessary in order to draw definitive conclusion.