Impact of positive legionella urinary antigen test on patient management and improvement of antibiotic use

Association between the Timing of Urinary Antigen Testing and Outcomes in Legionella Pneumonia Patients: A Nationwide Database Study

Objective Recommendations on the timing of Legionella urinary antigen tests for community-acquired pneumonia patients differ among guidelines in Japan, the United States, and European nations. We therefore evaluated the association between the timing of urinary antigen tests and in-hospital mortality in patients with Legionella pneumonia. Methods We conducted a retrospective cohort study using the Diagnosis Procedure Combination database, a nationwide database of acute care inpatients in Japan. Patients who underwent Legionella urinary antigen tests on the day of admission formed the tested group. Patients who were tested on day 2 of admission or later or were unexamined formed the control group. We performed a propensity score matching analysis to compare in-hospital mortality, length of hospital stay and duration of antibiotics use between the two groups. Results Of the 9,254 eligible patients, 6,933 were included in the tested group. One-to-one propensity score matching generated 1,945 pairs. The tested group had a significantly lower 30-day in-hospital mortality than the control group (5.7 vs. 7.7%; odds ratio, 0.72; 95% confidence intervals, 0.55-0.95; p=0.020). The tested group also showed a significantly shorter length of stay and duration of antibiotics use than the control group. Conclusion Urine antigen testing upon admission was associated with better outcomes in patients with Legionella pneumonia. Urine antigen tests upon admission may be recommended for all patients with severe community-acquired pneumonia.

Atraumatic Splenic Rupture in Legionella pneumophila Pneumonia

A previously fit 46-year-old male handyman presented to a rural hospital with a cough, fever, and epigastric pain without peritonism. The patient was admitted medically with symptoms and radiological appearances consistent with atypical community-acquired pneumonia. During the first 48 hours of admission, he suffered a significant haemodynamic deterioration and was transferred to the intensive care unit (ICU) for vasoactive support. Following stabilisation, urgent abdominal CT imaging demonstrated splenic rupture with haematoma in the absence of historical trauma. Emergency splenectomy was performed; the histopathological examination was unremarkable. Investigations for the presenting complaint confirmed Legionella pneumophila serotype 1 pneumonia by urinary antigen testing. The patient was extubated on postoperative day 2 and stepped down from ICU to complete a 14-day course of azithromycin. Atraumatic splenic rupture is a rarely described clinical entity. The process can be subdivided into pathological and nonpathological (spontaneous) cases. Pathological atraumatic splenic rupture may occur in the context of wide-ranging aetiologies, including bacterial pneumonia; however, the association with Legionella pneumophila serotype 1 is exceptional, with this representing the eighth case in the medical literature.

Clinical and Laboratory Diagnosis of Legionella Pneumonia

Legionella pneumonia is a relatively rare but extremely progressive pulmonary infection with high mortality. Traditional cultural isolation remains the gold standard for the diagnosis of Legionella pneumonia. However, its harsh culture conditions, long turnaround time, and suboptimal sensitivity do not meet the clinical need for rapid and accurate diagnosis, especially for critically ill patients. So far, pathogenic detection techniques including serological assays, urinary antigen tests, and mass spectrometry, as well as nucleic acid amplification technique, have been developed, and each has its own advantages and limitations. This review summarizes the clinical characteristics and imaging findings of Legionella pneumonia, then discusses the advances, advantages, and limitations of the various pathogenetic detection techniques used for Legionella pneumonia diagnosis. The aim is to provide rapid and accurate guiding options for early identification and diagnosis of Legionella pneumonia in clinical practice, further easing healthcare burden.

Diagnostic Study to Assess the Performance of a New Urinary Legionella Antigen Test-A National Study in Three Referral University Hospitals in Austria during 2014-2017

BACKGROUND

We evaluated the performance of a rapid diagnostic antigen test (Coris) as an index test versus the urinary Antigen ELISA (Bartels) as the reference test.

METHODS

Prospective diagnostic accuracy study (2014-2017) at three university hospitals in Austria.

RESULTS

A total of 996 patients were included in the study. Legionellosis was diagnosed in 49/996 (4.9%) using the reference test. The sensitivity and specificity of the Coris test were 75.5% (95% CI 61.1-86.7%) and 100% (95%CI 99.6-100%), respectively. The PPV was 100% and when using the lower 95% CI limit of the estimate for sensitivity, the resulting PPV was 61.1%. The NPV was 98.7% and the accuracy was 98.8%. The index test showed a PPV > 97% during the period of summer and autumn (May through November) and ≥88% during winter (December through February). The NPV was >97% during all of the periods. The median of the monthly incidence in the general population was 0.1 per 100,000 (IQR 0.1; 0.3).

CONCLUSION

The new rapid test gave a high level of diagnostic accuracy in a rapid fashion. The test can be applied at the bedside by non-laboratory staff.

Legionella pneumophila in Patients with Pneumonia at a Referral Hospital, New Delhi, India, 2015-2020

Legionnaires' disease (LD) is an established cause of pneumonia, and the disease remains largely underdiagnosed. Even though LD has been reported from many parts of the world, only sporadic cases have been reported in India. During February 2015-January 2020, we enrolled 597 patients with radiographically confirmed pneumonia and tested respiratory secretions for Legionella spp. by using real-time PCR, and culture. A commercial urinary antigen test (UAT) was also used to detect the Legionella pneumophila (Lp) serogroup 1 antigen in urine. An LD case was defined as a patient with pneumonia and positive results for Legionella spp. infections determined by real-time PCR (from any respiratory specimen) or culture or UAT. Demographic data, risk factors, clinical, radiological, and outcome data of Lp-positive and Lp-negative patients were compared using logistic regression. Over the study period, 14 (2.3%) patients were positive for Legionella spp. infections by real-time PCR and UAT; eight (57%) were admitted to the intensive care unit, and four (28.6%) in-hospital deaths occurred. Bivariate analysis showed that renal disease, neurological conditions, confusion, leukocytosis, and requirement of oxygen support were more common in the Lp-positive group than in the Lp-negative group. However, multivariate analysis failed to confirm most of these differences; renal disease was the only independent variable remaining significant. All test methods have intrinsic limitations in identifying Legionella; therefore, more than one testing method should be used. Application of molecular assays including real-time PCR has great value because of its high sensitivity, specificity, and rapid diagnostic potency. Increased awareness and improved diagnostic testing could facilitate early detection of cases, pathogen-directed therapy, and improved outcomes for patients.

Urinary antigen testing in community-acquired pneumonia in adults: an update

INTRODUCTION

Community-acquired pneumonia (CAP) continues to be a leading cause of hospitalization and mortality worldwide. Streptococcus pneumoniae and Legionella pneumophila remain the major etiological agents and are responsible for a significant proportion of CAP mortality. Among diagnostic tests for CAP, urine antigen detection of S. pneumoniae and L. pneumophila is widely accepted due to the simplicity of collection and the rapidity of the test results. Areas covered: This comprehensive review outlines the urinary antigen tests available, discusses their sensitivity and specificity, and assesses the usefulness of their results as the basis for targeted therapy. Expert commentary: There have been advances in urine antigen detection tests for patients with CAP. New methodologies show greater sensitivity, detect S. pneumoniae and L. pneumophila in a single test, and also detect pneumococcal serotypes. In addition, urine antigen detection tests have shown a high specificity, which means that a positive result practically indicates the causative pathogen of CAP. Therefore, a positive result can lead to a targeted therapy that is likely to improve patient outcomes and reduce the risk of resistance and adverse events. However, well-designed studies are needed to evaluate the usefulness of urine antigen detection tests with regard to clinical outcomes.

Evaluation and Comparison of Multiple Test Methods, Including Real-time PCR, for Legionella Detection in Clinical Specimens

Legionella is a Gram-negative bacterium that can cause Pontiac fever, a mild upper respiratory infection and Legionnaire’s disease, a more severe illness. We aimed to compare the performance of urine antigen, culture, and polymerase chain reaction (PCR) test methods and to determine if sputum is an acceptable alternative to the use of more invasive bronchoalveolar lavage (BAL). Data for this study included specimens tested for Legionella at Public Health Ontario Laboratories from 1st January, 2010 to 30th April, 2014, as part of routine clinical testing. We found sensitivity of urinary antigen test (UAT) compared to culture to be 87%, specificity 94.7%, positive predictive value (PPV) 63.8%, and negative predictive value (NPV) 98.5%. Sensitivity of UAT compared to PCR was 74.7%, specificity 98.3%, PPV 77.7%, and NPV 98.1%. Out of 146 patients who had a Legionella-positive result by PCR, only 66 (45.2%) also had a positive result by culture. Sensitivity for culture was the same using either sputum or BAL (13.6%); sensitivity for PCR was 10.3% for sputum and 12.8% for BAL. Both sputum and BAL yield similar results regardless testing methods (Fisher Exact p-values = 1.0, for each test). In summary, all test methods have inherent weaknesses in identifying Legionella; therefore, more than one testing method should be used. Obtaining a single specimen type from patients with pneumonia limits the ability to diagnose Legionella, particularly when urine is the specimen type submitted. Given ease of collection and similar sensitivity to BAL, clinicians are encouraged to submit sputum in addition to urine when BAL submission is not practical from patients being tested for Legionella.

Current and emerging Legionella diagnostics for laboratory and outbreak investigations

Legionnaires' disease (LD) is an often severe and potentially fatal form of bacterial pneumonia caused by an extensive list of Legionella species. These ubiquitous freshwater and soil inhabitants cause human respiratory disease when amplified in man-made water or cooling systems and their aerosols expose a susceptible population. Treatment of sporadic cases and rapid control of LD outbreaks benefit from swift diagnosis in concert with discriminatory bacterial typing for immediate epidemiological responses. Traditional culture and serology were instrumental in describing disease incidence early in its history; currently, diagnosis of LD relies almost solely on the urinary antigen test, which captures only the dominant species and serogroup, Legionella pneumophila serogroup 1 (Lp1). This has created a diagnostic "blind spot" for LD caused by non-Lp1 strains. This review focuses on historic, current, and emerging technologies that hold promise for increasing LD diagnostic efficiency and detection rates as part of a coherent testing regimen. The importance of cooperation between epidemiologists and laboratorians for a rapid outbreak response is also illustrated in field investigations conducted by the CDC with state and local authorities. Finally, challenges facing health care professionals, building managers, and the public health community in combating LD are highlighted, and potential solutions are discussed.

Importance of Legionella pneumophila in the etiology of severe community-acquired pneumonia in Santiago, Chile

BACKGROUND

In US and European literature, Legionella pneumophila is reported as an important etiologic agent of severe community-acquired pneumonia (CAP), but in Chile this information is lacking. The aim of this study was to determine the incidence and identify predictors of severe CAP caused by L pneumophila in Santiago, Chile.

METHODS

A multicenter, prospective clinical study lasting 18 months was conducted; it included all adult patients with severe CAP admitted to the ICUs of four hospitals in Santiago. We excluded patients who were immunocompromised, had been hospitalized in the previous 4 weeks, or presented with another disease during their hospitalization. All data for the diagnosis of severe CAP were registered, and urinary antigens for L pneumophila serogroup 1 were determined.

RESULTS

A total of 104 patients with severe CAP were included (mean ± SD age, 58.3 ± 19.3 years; men, 64.4%; APACHE (Acute Physiology and Chronic Health Evaluation) II score, 16.7 ± 6.3; Sepsis-related Organ Failure Assessment score, 6.1 ± 3.2; Pitt Bacteremia Score, 3.4 ± 2.5; Pao2/Fio2, 170.8 ± 87.1). An etiologic agent was identified in 62 patients (59.6%), with the most frequent being Streptococcus pneumoniae (27 patients [26%]) and L pneumophila (nine patients [8.6%]). Logistic regression analysis showed that a plasma sodium level of ≤ 130 mEq/L was an independent predictor for L pneumophila severe CAP (OR, 11.3; 95% CI, 2.5-50.5; P = .002). Global mortality was 26% and 33% for L pneumophila. The Pitt bacteremia score and pneumonia score index were the best predictors of mortality.

CONCLUSIONS

We found that in Santiago, L pneumophila was second to S pneumoniae as the etiologic agent of severe CAP. Severe hyponatremia at admission appears to be an indicator for L pneumophila etiology in severe CAP.

Diagnosis of community-acquired pneumonia in adults

Community-acquired pneumonia (CAP) is a common presentation to both primary and secondary care, representing approximately 5% of the acute medical intake in the UK. Treatment is often based on an empirical approach, using broad-spectrum antibiotic regimens, with which the majority of patients will achieve clinical cure. However, in cases of severe CAP, initial treatment failure or severe comorbidity, a more rigorous diagnostic approach is required. This review assesses the evidence base behind the common diagnostic methods for CAP, and presents the case for a rapid and accurate microbiological and radiological diagnosis in improving management and outcomes of this common condition.

Detection of Legionella pneumophila serogroup 1 antigen in respiratory samples using an immunochromatographic membrane test

The immunochromatographic membrane test (ICT) efficacy of Legionella antigen detection (Binax Now Legionella) was evaluated using respiratory samples, including bronchial washings (44 cases) and sputum (128 cases), from suspected Legionella pneumonia patients. The ICT results using respiratory samples agreed well with isolation of L. pneumophila SG1 and ICT using urines.

Pulmonary complications of haematopoietic cell transplantation in children

Paediatric haematopoietic cell transplantation has experienced significant advances in the last few decades. However, pulmonary complications are an important limitation to the efficacy of this intervention, contributing to post-transplantation morbidity and mortality. Such complications persist even in experienced centres and occur in adult and paediatric recipients. This review identifies the paediatric pulmonary complications that are commonly seen following haematopoietic cell transplantation and addresses both infectious and non-infectious aetiologies and their clinical manifestations, evaluation, and potential therapy. Ultimately, improvement in outcomes will require attention to immunosuppression as well as traditional diagnostic procedures and treatment. This article aims to review the current state of pulmonary complications post-transplantation, to examine the impact of our recent advances and changes in treatment, and to identify potential future therapies and hypothesise what role these might have on long-term survival.