Detection Of Legionella Pneumophila Serogroup Research Articles

Legionnaires' Disease: Update on Diagnosis and Treatment.

Legionellosis is the infection caused by bacteria of the genus Legionella, including a non-pneumonic influenza-like syndrome, and Legionnaires’ disease is a more serious illness characterized by pneumonia. Legionellosis is becoming increasingly important as a public health problem throughout the world; although it is an underreported disease, studies have consistently documented a high incidence. In addition, health costs associated with the disease are high. Diagnosis of Legionnaires’ disease is based mainly on the detection of Legionella pneumophila serogroup 1 antigen in urine. However, there have been advances in detection tests for patients with legionellosis. New methodologies show greater sensitivity and specificity, detect more species and serogroups of Legionella spp., and have the potential for use in epidemiological studies. Testing for Legionella spp. is recommended at hospital admission for severe community-acquired pneumonia, and antibiotics directed against Legionella spp. should be included early as empirical therapy. Inadequate or delayed antibiotic treatment in Legionella pneumonia has been associated with a worse prognosis. Either a fluoroquinolone (levofloxacin or moxifloxacin) or a macrolide (azithromycin preferred) is the recommended first-line therapy for Legionnaires’ disease; however, little information is available regarding adverse events or complications, or about the duration of antibiotic therapy and its association with clinical outcomes. Most published studies evaluating antibiotic treatment for Legionnaires’ disease are observational and consequently susceptible to bias and confounding. Well-designed studies are needed to assess the usefulness of diagnostic tests regarding clinical outcomes, as well as randomized trials comparing fluoroquinolones and macrolides or combination therapy that evaluate outcomes and adverse events.

Legionnaires' disease - a qualitative study on Swiss physicians' approaches to the diagnosis and treatment of community-acquired pneumonia.

The number of reported cases of Legionnaires' disease has increased significantly over the last decade in Switzerland and abroad. Along with the number of cases, the volume of testing has increased as well, which has been partially attributed to a change in awareness of the disease. Yet, while there are numerous guidelines and recommendations for the case management of community-acquired pneumonia, little is known about how physicians in Switzerland perceive and manage Legionnaires' disease. This study aimed to investigate physicians' awareness of Legionnaires' disease, their information resources and their approach to the diagnosis and treatment of pneumonia (and thus Legionnaires' disease). Using a semi-structured interview guide, we conducted in-depth interviews with physicians from different levels of care and from the German-, French- and Italian-speaking regions of Switzerland. We conducted 46 interviews with physicians from university, cantonal and regional hospitals as well as with general practitioners (GPs) from all three language regions. Overall, the physicians working in hospitals indicated a similar level of awareness of Legionnaires' disease, and comparable diagnosis and treatment approaches. The Legionella urine antigen test (UAT) was reported to be routinely performed in inpatients. In contrast, GPs indicated lower levels of awareness, reflecting the fact that they treat pneumonia cases empirically without identification of the causative agent, in accordance with current guidelines. The value of the diagnostic tests in general and the Legionella UAT in particular was considered to be dependent on the (preferred) antibiotic treatment approach. Some physicians saw the test as redundant, as its result would not influence treatment. This was tied to concerns about the UAT's sensitivity and its limited use for the detection of Legionella pneumophila serogroup 1. Lastly, extrinsic constraints, such as financial and time considerations also affected physicians' testing and treatment preferences. Awareness of Legionnaires' disease is overall high, yet cases are mainly diagnosed and reported by hospitals. Improved diagnostic tools are needed to support physicians in reducing underestimation of Legionnaires' disease and optimise antibiotic stewardship without compromising patient health outcomes.

Method Comparison of the ImmuView L. pneumophila and L. longbeachae Urinary Antigen Test with the BinaxNOW Legionella Urinary Antigen Card for Detection of Legionella pneumophila Serogroup 1 Antigen in Urine.

We compared the clinical performance of the ImmuView L. pneumophila and L. longbeachae urinary antigen test (SSI Diagnostica A/S, Hillerød, Denmark) to that of the BinaxNOW Legionella urinary antigen card (Binax; Abbott, Lake Buff, IL) using urine specimens from patients suspected of having pneumonia. In total, 100 frozen urine samples (derived from 50 Legionella cases and 50 noncases) were analyzed with both tests, as were 200 nonfrozen prospectively collected samples. For urine samples from five Legionella cases and two non-Legionella cases, analytical sensitivity (limit of detection) and repeatability were examined. The urine samples from the five Legionella cases were diluted with urine samples that tested Legionella urinary antigen negative with both tests. The analyses of the 100 frozen samples resulted in a sensitivity and specificity of both ImmuView and the BinaxNOW of 96.0% (48/50) and 100% (50/50), respectively. Of the 200 nonfrozen samples, there were three samples that showed a positive result for L. pneumophila by both tests. The analyses of reproducibility showed that for the 34 (diluted) samples that were tested at two consecutive times, 33 samples showed a consistent result for both the ImmuView and the BinaxNOW tests (Cohen's kappa values of 0.916 and 0.928). In addition, the ImmuView test may have detected two L. longbeachae-positive urine samples, although other diagnostic tests could not confirm this. Both ImmuView and BinaxNOW showed high sensitivity and specificity for the detection of L. pneumophila serogroup 1 antigen in urine samples from clinical patients with a suspected lower respiratory tract infection.

Evaluation of the bioNexia Legionella Test, Including Impact of Incubation Time Extension, for Detection of Legionella pneumophila Serogroup 1 Antigen in Urine

In this study, we compared the bioNexia test (bioMérieux, Marcy-l'Étoile, France), a new immunochromatographic assay for the detection of Legionella pneumophila serogroup 1 in urine, with the BinaxNOW urinary antigen test (Alere, Waltham, Massachusetts, USA). After 15 min of incubation (in accordance with the manufacturers' instructions), the sensitivities and specificities were, respectively, 76.5% and 97.2% for the bioNexia test and 87.1% and 100% for the BinaxNOW test. After a prolonged incubation time of 60 min, the sensitivities and specificities increased to, respectively, 89.4% and 97.2% for the bioNexia test and 91.8% and 100% for the BinaxNOW test. When the tests were read after 15 min, the concentration of discrepant urine samples increased the sensitivities to 94.1% for both tests. In conclusion, we found that although the bioNexia test showed lower sensitivity for the detection of L. pneumophila antigen in nonconcentrated urine compared to the BinaxNOW test, a prolonged incubation time as well as the use of concentrated samples showed comparable sensitivities for both tests.

Evaluation of Meridian TRU Legionella®, a new rapid test for detection of Legionella pneumophila serogroup 1 antigen in urine samples

We evaluated the ability of a new antigen test (TRU Legionella® assay, Meridian Bioscience, Cincinnati, OH, USA) to detect Legionella pneumophila serogroup 1 antigen in urine. The results were compared with those obtained with the Binax NOW® urinary antigen test (Binax, Portland, ME, USA). The sensitivities and specificities were 73 % [95 % confidence interval (CI), 65 to 81 %] and 100 %, respectively, for the Meridian TRU Legionella test and 77 % (95 % CI, 68 to 84 %) and 100 %, respectively, for the Binax NOW urinary antigen test. The sensitivity of the Meridian TRU Legionella test increased to 81 % if tests were re-examined after 60 min of incubation. Prolonged incubation did not affect the specificity. We conclude that both assays evaluated have similar performance characteristics and are suitable for the rapid diagnosis of Legionnaires' disease.

Detection of Legionella pneumophila serogroup 1 in blood cultures from a patient treated with tumor necrosis factor-alpha inhibitor

A 65-year-old man was admitted to our hospital with a temperature of 39.3 °C, cough, sputum, and pharyngeal discomfort that had persisted for 3 days. He had been treated with methotrexate and adalimumab (a tumor necrosis factor-alpha [TNF-α] inhibitor) for rheumatoid arthritis for 2 years, and he had also been treated with S-1 (tegafur, gimeracil, and oteracil potassium) for pancreatic metastasis of gastric cancer for 2 months. Regardless of the underlying pathologies, his general condition was good and he had worked as an electrician until 2 days before admission. However, his appetite had suddenly decreased from the day before admission, and high fever and hypoxia were also evident upon admission. A chest X-ray and computed tomography scan revealed left pleural effusion and consolidation in both lungs. The pneumonia severity index score was 165 and the risk class was V. Accordingly, we started to treat the pneumonia with a combination of levofloxacin and meropenem. Thereafter, we received positive urinary antigen test findings for Legionella pneumophila. After hospitalization, hypoxia was progressed and hypotension was emerged. Despite the application of appropriate antibiotics, vasopressors, and oxygenation, the patient died 8 h after admission. Even after his death, blood cultures were continued to consider the possibility of bacterial co-infection. Although no bacteria were detected from blood cultures, Gimenez staining revealed pink bacteria in blood culture fluids. Subsequent blood fluid culture in selective medium revealed L. pneumophila serogroup 1. Recently, TNF-α inhibitors have been described as a risk factor for Legionnaires' disease. In consideration of the increased frequency of TNF-α inhibitors, we may need to recognize anew that L. pneumophila might be a pathogen of severe community-acquired pneumonia.

Legionella, légionellose

Legionella is the causative agent of Legionnaires' disease, a severe form of pneumonia. Detection of Legionella pneumophila serogroup 1 antigen in urine samples has shortened the delay of diagnosis and subsequent treatment initiation resulting in decreased mortality. Improved surveillance of potable water system reinforces the community prevention. In France, the National Reference Center for Legionella collects the strains responsible for sporadic or epidemic cases and crosslinks the data including epidemiological pattern, clinical presentation, and genetic analysis of the strains. Regarding host-pathogen interactions, major advances have been made recently in the understanding of L. pneumophila ability to subvert the host intracellular trafficking and the innate immune response leading to infection control.

Evaluation of a new rapid test for detection of Legionella pneumophila serogroup 1 antigen in urine

For the diagnosis of legionellosis, a new rapid immunochromatographic test (V-tesT CORIS BioConcept) for detection of Legionella pneumophila serogroup 1 antigen in urine was evaluated in 21 samples of patients with legionellosis and 45 samples from patients with other respiratory infections. Results were compared with those obtained by a commercially reference test (BinaxNOW Legionella - Binax).The overall sensitivity was 90.4% for both tests; concordance was 100%; specificity was 100% as well. In conclusion, the V-tesT CORIS seems to be a prompt and suitable diagnostic tool in legionellosis diagnosis.

Investigation of an outbreak of Legionnaires’ disease: Hereford, UK 2003

This report describes the investigation and control of a community outbreak of Legionnaires' disease in Hereford, UK, in November 2003. Outbreak investigation consisted of epidemiological survey, identification and environmental investigation of potential sources, microbiological analysis of clinical and environmental samples and mapping the location of potential sources and the movement and residence of cases. Each identified source was allocated a 'composite score' based on different zones of exposure and wind direction. Altogether, 28 cases were identified, with an overall case fatality rate of 7%. All cases had epidemiological links to Hereford city centre. The 'composite score' identified a cluster of cooling towers as being the most likely source of the outbreak. Environmental samples from one of the cooling towers in the cluster and clinical samples from two patients were positive for Legionella pneumophilia serogroup 1 and were indistinguishable by molecular sub-typing. In this outbreak, the use of microbiological, environmental and epidemiological techniques facilitated the rapid identification of a cooling tower as the source of this outbreak. This study illustrates the continuing importance of cooling towers as a source of Legionnaires' disease and the utility of obtaining and comparing both clinical and environmental samples.

Evaluation of the SAS Legionella Test, a new immunochromatographic assay for the detection of Legionella pneumophila serogroup 1 antigen in urine

This study evaluated a new immunochromatographic assay (SAS Legionella Test) for its ability to detect Legionella pneumophila serogroup 1 antigen in urine. Results were compared with those obtained using the Binax Now urinary antigen test. Sensitivity and specificity were estimated as 82.9% and 99.0%, respectively, for the SAS Legionella Test, and 91.4% and 100%, respectively, for the Binax Now urinary antigen test. The sensitivity of both tests increased to 97.1% (p 0.009) and 94.2% (p 0.7), respectively, if the tests were examined after 1 h.

Detection of Legionella pneumophila serogroup 7 strain from bathwater samples in a Japanese hospital

Hospital-acquired legionellosis is one of the serious problems in nosocomial infection. For risk assessment of nosocomial Legionella infection, we surveyed samples from bathrooms for public use in three hospitals and two nursing homes to determine whether Legionella pneumophila was present. A total of 70 hot bathwater samples and samples wiped from bathtubs were collected at 1-h intervals. Fifteen shower-water and 15 inner-head samples were obtained at the start of a bath. Water samples were cultured using the Legionella spp. selective medium, and discrimination between L. pneumophila and other Legionella spp. was performed by PCR analysis. L. pneumophila serogroup 7 was detected in 1 bathwater and 1 wiped sample, both of which were collected 1 h after daily use from the same bathtub in a hospital. However, L. pneumophila SG7 was not detected in any other samples. Furthermore, the concentrations of free residual chlorine in most bath- and shower-water samples were lower than 0.1 mg/l. These results suggest that L. pneumophila has become a potential pathogen for nosocomial infections in public-type hospital baths. From the point of view of an infection-control program, it might be advisable to hold the concentration of free residual chlorine at 0.2-0.4 mg/l, which is generally required for public baths in Japan.

Value of intensive diagnostic microbiological investigation in low- and high-risk patients with community-acquired pneumonia

In a prospective study to evaluate the diagnostic yield of different microbiological tests in hospitalised patients with community-acquired pneumonia, material for microbiological investigation was obtained from 262 patients. Clinical samples consisted of the following: sputum for Gram staining, culture, and detection of pneumococcal antigen; blood for culture and serological tests; urine for detection of Legionella pneumophila serogroup 1 antigen and pneumococcal antigen; and specimens obtained by fiberoptic bronchoscopy. A pathogen was identified in 158 (60%) patients, with Streptococcus pneumoniae (n=97) being the most common causative agent of community-acquired pneumonia. In 82% of the 44 patients with an adequate sputum specimen, a positive Gram stain was confirmed by positive sputum culture. S. pneumoniae infections were detected principally when adequate sputum specimens were examined by Gram stain and culture and when adequate and inadequate sputum specimens were tested for the presence of pneumococcal antigen (n=58; 60%). The urinary pneumococcal antigen test was the most valuable single test for detection of S. pneumoniae infections (n=52; 54%) when sputum pneumococcal antigen determination was not performed. Fiberoptic bronchoscopy was of additive diagnostic value in 49% of the patients who did not expectorate sputum and in 52% of those in whom treatment failed. Investigation of sputum by a combination of Gram stain, culture, and detection of pneumococcal antigen was the most useful means of establishing an aetiological diagnosis of community-acquired pneumonia, followed by testing of urine for pneumococcal antigen. Fiberoptic bronchoscopy may be of additional value when treatment failure occurs.

Evaluation of the Bartels Legionella Urinary Antigen Enzyme Immunoassay

The Bartels Legionella Urinary Antigen enzyme immunoassay (Intracel, USA) is intended for the presumptive diagnosis of past or current Legionnaires' disease by qualitative detection of Legionella pneumophila serogroup 1 antigen in human urine. This test was evaluated using single urine samples collected from 349 patients with lower respiratory tract infection of known aetiology. Specificity was estimated as 100% (181 samples, 95% CI: 98%-100%); sensitivity for Legionella pneumophila serogroup 1 was 98.8% (167 samples, 95% CI: 95.7%-99.9%). Assessing assay results using a Visual Interpretation Card provided by the manufacturer in place of a photometer gave rise to one false-positive result among the 78 control samples examined. Providing the endpoint of this assay is determined photometrically, the Bartels Legionella Urinary Antigen enzyme immunoassay appears to be a highly specific and sensitive kit for the diagnosis of infection caused by Legionella pneumophila serogroup 1.

Rapid diagnosis of Legionnaires' disease using an immunochromatographic assay for Legionella pneumophila serogroup 1 antigen in urine during an outbreak in the Netherlands.

A new immunochromatographic assay for rapid qualitative detection of Legionella pneumophila serogroup 1 antigen in urine specimens was used during an outbreak of legionellosis in The Netherlands. The assay seems of the utmost value in providing a rapid diagnosis of Legionnaires' disease in patients with severe community-acquired pneumonia in an outbreak setting.

Comparison of radioimmunoassay and enzyme immunoassay kits for detection of Legionella pneumophila serogroup 1 antigen in both concentrated and nonconcentrated urine samples

We evaluated a commercial enzyme immunoassay (EIA) kit for detection of Legionella pneumophila serogroup 1 soluble antigen by comparing it to radioimmunoassay (RIA), using both concentrated and nonconcentrated urine samples. The sensitivity of EIA was 67.4% in nonconcentrated urine samples and 82.6% in concentrated urine samples. The sensitivity of RIA was 60.9% and 84.8% in nonconcentrated and concentrated urine samples, respectively. Our study indicates that the sensitivity and specificity of EIA are comparable to those of RIA, and that concentrating the antigen by selective ultrafiltration increases sensitivity for both EIA and RIA, with no significant decrease in specificity.

Assessment of enzyme immunoassay versus radioimmunoassay for detection of Legionella pneumophila serogroup 1 antigen in frozen urine specimens.

An enzyme immunoassay (EIA) was compared with a radioimmunoassay (RIA) for detection of Legionella pneumophila serogroup 1 antigen in 37 frozen urine samples. Among 18 samples positive by the RIA at the time of collection, 50% (9 of 18) of stored specimens retained positivity when retested by the RIA whereas 78% (14 of 18) of stored specimens retained positivity when retested by the EIA (P < 0.02). A false-negative result occurred after storage for 5 months or less if the original RIA result showed weak positivity.

Detection of Legionella pneumophila serogroup 1 antigen in nonconcentrated urine and urine concentrated by selective ultrafiltration.

We evaluated a commercially available radioimmunoassay technique for detecting the soluble antigen of Legionella pneumophila serogroup 1 using concentrated and nonconcentrated urine. Concentration was achieved by selective ultrafiltration. The sensitivity of the technique was 60.9% for nonconcentrated urine and 80.4% for concentrated samples, with 100% specificity in both cases.

Prevalence and Diagnosis of Legionella Pneumonia: A 3-Year Prospective Study with Emphasis on Application of Urinary Antigen Detection

During a 3-year period the frequency of legionellosis in hospitalized patients with community-acquired and nosocomial pneumonias was 3.4% (23/684 cases) and 5.9% (33/559), respectively. Of the diagnostic tests evaluated, detection of Legionella pneumophila serogroup 1 antigen in urine had the highest sensitivity, with 86% of culture-proven cases being positive. Sensitivities of serologic tests and examination of respiratory secretions (culture and direct immunofluorescence) were 36% and 26%, respectively. The diagnostic value of serology and of examination of respiratory secretions can be low when specimens are obtained and processed under the typical conditions of hospitalization. Urinary antigen detection represents an important diagnostic addition, and examination of postmortem lung tissue from fatal cases with pneumonia is an important adjunct for estimating the prevalence of legionellosis and for assessing the effectiveness of premortem diagnostic tests.

Immunohistological detection of Legionella pneumophila in lung sections.

Immunohistology was used for the detection of Legionella pneumophila serogroup I in necropsy tissue. Study of pneumonic lung from the recent Stafford outbreak has shown that this technique has a high sensitivity. A retrospective postmortem examination showed that L pneumophila serogroup 1 was an unusual cause of pneumonia in Oxfordshire during the study period. L pneumophila serogroup 1 can be successfully subgrouped, using a panel of monoclonal antibodies on formalin fixed paraffin embedded sections. Immunohistological methods have a potentially useful role in the diagnosis of Legionellosis at postmortem examination and in the epidemiological investigation of individual cases and outbreaks.