BACKGROUND: In case of pneumonia, some biological findings are suggestive for Legionnaire\'s disease (LD) including C-reactive protein (CRP). A low level of CRP is predictive for negative Legionella Urinary-Antigen-Test (L-UAT).
METHODS: Observational retrospective study in Nord-Franche-Comté Hospital with external validation in Besançon University Hospital, France which included all adults with L-UAT performed during January 2018 to December 2022. The objective was to determine CRP optimal threshold to predict a L-UAT negative result.
RESULTS: URINELLA included 5051 patients (83 with positive L-UAT). CRP optimal threshold was 131.9 mg/L, with a negative predictive value (NPV) at 100%, sensitivity at 100% and specificity at 58.0%. The AUC of the ROC-Curve was at 88.7% (95% CI, 86.3-91.1). External validation in Besançon Hospital patients showed an AUC at 89.8% (95% CI, 85.5-94.1) and NPV, sensitivity and specificity was respectively 99.9%, 97.6% and 59.1% for a CRP threshold at 131.9 mg/L; after exclusion of immunosuppressed patients, index sensitivity and NPV reached also 100%.
CONCLUSIONS: In case of pneumonia suspicion with a CRP level under 130 mg/L (independently of the severity) L-UAT is useless in immunocompetent patients with a NPV at 100%. We must remain cautious in patients with symptoms onset less than 48 h before CRP dosage.

A 79-year-old man presented with chest pain, and urinary antigen tests for Legionella pneumophila (ImmunoCatch® Legionella and Ribotest® Legionella) were negative on admission. The next day, rapid respiratory failure suggested Legionella pneumonia, and levofloxacin was added. Since a lung infiltration shadow appeared on the other side as well on day 4, non-infectious diseases were considered, and steroid therapy was started. Urinary antigen tests for Legionella pneumophila became positive on day 5. In the present case, retesting with Ribotest® Legionella, which could be negative early after the disease onset, was useful for diagnosing Legionella pneumonia, which led to the discontinuation of unnecessary steroid treatment.

We compared the performance of STANDARD F S. pneumoniae Ag FIA with that of BinaxNOW S. pneumoniae Antigen Card using 206 urine samples. The performance of STANDARD F was highly comparable to that of BinaxNOW. STANDARD F assay could be a valuable tool for diagnosis of invasive pneumococcal disease.

To evaluate the effect of pneumococcal urinary antigen test (UAT) usage on broad-spectrum antibiotic treatment in community-acquired pneumonia (CAP).
Patients admitted to 32 Swedish hospitals between 2011 and 2014 were retrospectively included from the Swedish National Quality Register of CAP. Using propensity score matched data, stratified by CRB-65 score, we studied the effect of performing UAT and of positive test results on treatment with broad-spectrum β-lactam monotherapy (BSBM) and antibiotics with coverage for atypical bacteria compared to narrow-spectrum β-lactam monotherapy (NSBM).
UAT was performed for 4,995/14,590 (34.2%) patients, 603/4,995 (12.1%) of whom had positive test results. At day three, performing UAT was not associated with decreased use of BSBM (OR 1.07, 95% CI 0.94-1.23) but was associated with increased atypical coverage among patients with CRB-65 score 2 (OR 1.47, 95% CI 1.06-2.02). A positive UAT was associated with decreased BSBM use (OR 0.39, 95% CI 0.25-0.60) and decreased atypical coverage (OR 0.25, 95% CI 0.16-0.37), predominantly in non-severe CAP. At day one, performing UAT was associated with atypical coverage among patients with CRB-65 scores 2 (OR 2.60, 95% CI 1.69-3.98) and 3-4 (OR 3.69, 95% CI 1.55-8.79), and a positive test reduced the odds of BSBM treatment among CRB-65 score 3-4 patients (OR 3.49, 95% CI 1.02-12.0).
Performing UAT had no overall effect on decreasing the use of BSBM treatment by day three of hospitalization, yet non-severely ill patients with positive UAT results were less likely to be treated with BSBM and antibiotics with atypical coverage.

Pneumonia is a leading cause of hospitalization and death due to infection worldwide. Streptococcus pneumoniae and Legionella pneumophila remain among the most commonly identified bacterial pathogens. Unfortunately, more than half of all pneumonia cases today lack an etiologic diagnosis due to limitations in traditional microbiological methods like blood and sputum cultures, which are affected by poor sample collection, prior antibiotic administration, and delayed processing. Urinary antigen tests (UATs) for S. pneumoniae and L. pneumophila have emerged as powerful tools for improving the diagnosis of bacterial respiratory infections, enabling physicians to administer early directed therapy and improve antimicrobial stewardship. UATs are simple, rapid, and non-invasive diagnostic tests with high specificity (>90%) and moderate sensitivity (<80%). The potential impact of urinary antigen testing is especially significant for respiratory infections caused by Legionella. While all recommended community-acquired pneumonia (CAP) therapies are adequate for treating pneumococcal pneumonia, only certain antibiotics are effective against Legionella. Delayed therapy for Legionella is associated with worse clinical outcomes, which underscores the importance of rapid diagnostic methods like UATs. Despite their potential impact, current American Thoracic Society and Infectious Diseases Society of America (ATS/IDSA) guidelines argue against the routine use of urinary antigen testing for S. pneumoniae and L. pneumophila, except in patients with severe CAP and those with epidemiological risk factors for Legionella. Further research is necessary to evaluate the impact of early targeted treatment due to positive UAT results, as well as optimal strategies for UAT utilization. The purpose of this review is to summarize the UATs available for bacterial respiratory infections, describe current guidelines on their usage, and assess their impact on clinical outcomes and targeted therapy.

BACKGROUND: Urinary antigen tests (UATs) have been used for the early detection of legionellosis and have demonstrated moderate sensitivity and high specificity. However, the most recent systematic review and meta-analysis published in 2009 evaluated the accuracy of UATs; since then, UAT accuracy may have changed owing to advances and developments in UAT technology and epidemiological changes in the frequency of Legionella species that cause legionellosis. Therefore, this systematic review and meta-analysis aimed to update the accuracy of UATs for legionellosis among patients with suspected pneumonia.
METHODS: Overall, 1326 studies were screened, 21 of which fulfilled the eligibility criteria for quality assessment and meta-analysis. Data from 5772 patients, including 1368 (23.7%) with the target condition (i.e., suspected legionellosis), were included in the analysis. The overall quality of the included studies, which was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 tool, was unclear.
RESULTS: The calculated pooled sensitivity and specificity were 0.79 (95% confidence interval [CI], 0.71-0.85) and 1.00 (95% CI, 0.99-1.00), respectively. Subpopulation analysis revealed that the accuracy of UATs for sensitivity and specificity for Legionella pneumophilia serogroup 1 was 0.86 (95% CI, 0.78-0.91) and 1.00 (95% CI, 0.99-1.00), respectively.
CONCLUSIONS: This study demonstrated that the sensitivity and specificity of UATs were moderate and high, respectively, which is comparable to the results reported in 2009. Therefore, UATs may be a useful method for the early detection of legionellosis caused by Legionella pneumophila serogroup 1.
BACKGROUND: The review protocol was prospectively registered with the University Hospital Medical Information Network Clinical Trials Registry (UMIN000041080).

BACKGROUND: Bacterial culture remains the gold standard for the diagnosis of legionellosis. However, past reports indicate that most physicians use the urinary antigen test (UAT) alone. Combining it with other tests is important, especially in patients with negative UAT results. The aim of this study was to investigate the current situation of legionellosis diagnostics and clarify the issues that need to be addressed.
METHODS: Between March 1, 2021 and April 30, 2021, a questionnaire survey was conducted in an anonymous manner among physicians working in Japan. Questionnaires were generated on a website and asked questions in a multiple-choice format.
RESULTS: Valid responses were received from 309 physicians during the study period. Most (92.9%) physicians reported using UAT as the initial test for patients suspected of having legionellosis, and <10% reported using other tests (e.g., culture, nucleic acid amplification test [NAAT], Gimenez staining, and serum antibody titer measurement [ATM]). When the initial test result was negative, 63% of physicians reported not conducting additional tests. Even when they chose to run additional tests, at most 27.8%, 23.6%, 12.3%, and 10.4% of all physicians used NAAT, culture, Gimenez staining, and serum ATM, respectively. The major reasons for not using tests other than UAT were \"unavailability in the medical facility,\" \"long turn-around time,\" and \"difficult to collect sputum.\"
CONCLUSIONS: The present survey revealed that most physicians in Japan used UAT alone for diagnosing legionellosis. Eliminating barriers to creating a reasonable environment and edification of physicians are needed to improve the current situation.

BACKGROUND: Whether the sensitivity of the BinaxNOW Streptococcus pneumoniae urinary antigen test kit (BinaxNOW), adjusted by some variables including vital signs, laboratory examinations and pneumonia severity, has been decreasing is unknown. The aim of the present study was to investigate whether BinaxNOW sensitivity has decreased recently and to identify the predictors of the BinaxNOW result, including the time trend.
METHODS: This prospective cohort study enrolled consecutive patients with pneumococcal community-acquired pneumonia who were hospitalised at Kurashiki Central Hospital from January 2001 to December 2015. Pneumococcal community-acquired pneumonia was defined as positive blood or pleural effusion or sputum culture results. To evaluate the effect of the time trend for the sensitivity of BinaxNOW, time series regression analysis was performed. In addition, predictors of the BinaxNOW result were examined by multivariable analysis using variables such as sex, vital signs, blood tests such as C-reactive protein, albumin, blood urea nitrogen, creatinine, white blood cell count, haematocrit and platelets, antibiotic pre-treatment, bacteraemia, and pneumonia severity, in addition to time trend and seasonality.
RESULTS: A total of 446 patients were included. BinaxNOW sensitivity showed a significant, gradual decrease from 2001 (81.3%) to 2015 (48.7%). On multivariable analysis [odds ratio (95% confidence interval)], bacteraemia [2.516 (1.387-4.561), P = 0.002] was a predictor of a positive BinaxNOW result, whereas male sex [0.467 (0.296-0.736), P = 0.001], white blood cell count [0.959 (0.930-0.989), P = 0.008] and the time trend per year [0.900 (0.859-0.943), P < 0.001] were predictors of a negative BinaxNOW result.
CONCLUSIONS: The sensitivity of BinaxNOW decreased over a 15-year period. We should be careful when interpreting BinaxNOW results in daily clinical practice, and the development of a new kit with good sensitivity is anticipated.
BACKGROUND: UMIN000004353.

OBJECTIVE: The aim of this study was to evaluate the diagnostic utility of a novel test kit that could theoretically detect all serogroups of Legionella pneumophila for diagnosing Legionella pneumonia, in comparison with existing kits.
METHODS: This study was conducted in 16 hospitals in Japan from April 2016 to December 2018. Three urinary antigen test kits were used: the novel kit (LAC-116), BinaxNOW Legionella (Binax), and Q-line Kyokutou Legionella (Q-line). In addition, sputum culture and nucleic acid detection tests and serum antibody tests were performed where possible. The diagnostic accuracy and correlations of the novel kit with the two existing kits were analyzed.
RESULTS: In total, 56 patients were diagnosed with Legionella pneumonia. The sensitivities of LAC-116, Binax, and Q-line were 79%, 84%, and 71%, respectively. The overall match rate between LAC-116 and Binax was 96.8% and between LAC-116 and Q-line was 96.4%. One patient had L. pneumophila serogroup 2, and only LAC-116 showed a positive result, whereas Binax and Q-line did not.
CONCLUSIONS: The novel Legionella urinary antigen test kit was useful for diagnosing Legionella pneumonia. In addition, it could detect Legionella pneumonia caused by non-L. pneumophila serogroup 1.

The urinary antigen test (UAT) is a rapid diagnostic method for pneumococcal pneumonia, but the high false-negative rate of 30% may affect its reliability. To maximize the utility of UAT, it is necessary to investigate the patient factors affecting UAT results. However, there is no report elucidating the association between its utility and pre-existing lung abnormalities. We retrospectively reviewed 388 patients with pneumococcal pneumonia confirmed by blood and/or sputum culture tests. Finally, 94 of 388 patients who had the results of UAT and computed tomography scans were enrolled to evaluate the association between the utility of UAT and patient factors including pulmonary emphysema and fibrosis. The overall positive rate of UAT was 69.1%. The positive rates of UAT in the patients with emphysema were significantly lower than those in individuals without emphysema (33.3% and 77.6%, p < 0.001). Univariate logistic regression analysis showed that the presence of emphysema was associated with a low positive rate (odds ratio 6.944, 95% confidence interval 2.268-21.231). Multivariate logistic analysis showed that the presence of emphysema and lower levels of serum blood urea nitrogen (BUN) were significantly and independently associated with a low positive rate. The combination of emphysema and BUN can potentially stratify the positive rate of UAT in patients with pneumococcal pneumonia. Patients with pneumococcal pneumonia and emphysema have a lower positive rate of UAT. Additionally, the combination of emphysema and serum BUN value may be useful to evaluate the reliability of the negative results of pneumococcal UAT.