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

Venomous Arachnid Diagnostic Assays, Lessons from Past Attempts

Diagnostic tests for arachnid accidents remain unavailable for patients and clinicians. Together with snakes, these accidents are still a global medical concern, and are recognized as neglected tropical issues. Due to arachnid toxins’ fast mechanism of action, quick detection and quantification of venom is required to accelerate treatment decisions, rationalize therapy, and reduce costs and patient risks. This review aims to understand the current limitations for arachnid venom identification and quantification in biological samples. We benchmarked the already existing initiatives regarding test requirements (sample or biomarkers of choice), performances (time, detection limit, sensitivity and specificity) and their validation (on animal models or on samples from envenomed humans). Our analysis outlines unmet needs for improving diagnosis and consequently treatment of arachnid accidents. Hence, based on lessons from past attempts, we propose a road map for raising best practice guidelines, leading to recommendations for future progress in the development of arachnid diagnostic assays.

Aptamer-Based Technologies in Foodborne Pathogen Detection

Aptamers are single stranded DNA or RNA ligands, which can be selected by a method called systematic evolution of ligands by exponential enrichment (SELEX); and they can specifically recognize and bind to their targets. These unique characteristics of aptamers offer great potentials in applications such as pathogen detection and biomolecular screening. Pathogen detection is the critical means in detecting and identifying the problems related to public health and food safety; and only the rapid, sensitive and efficient detection technologies can enable the users to make the accurate assessments on the risks of infections (humans and animals) or contaminations (foods and other commodities) caused by various pathogens. This article reviews the development in the field of the aptamer-based approaches for pathogen detection, including whole-cell SELEX and Genomic SELEX. Nowadays, a variety of aptamer-based biosensors have been developed for pathogen detection. Thus, in this review, we also cover the development in aptamer-based biosensors including optical biosensors for multiple pathogen detection by multiple-labeling or label-free models such as fluorescence detection and surface plasmon resonance, electrochemical biosensors and lateral chromatography test strips, and their applications in pathogen detection and biomolecular screening. While notable progress has been made in the field in the last decade, challenges or drawbacks in their applications such as pathogen detection and biomolecular screening remain to be overcome.

Presence and Chromosomal Subtyping ofLegionellaSpecies in Potable Water Systems in 20 Hospitals of Catalonia, Spain

Objective:

To investigate the presence and clonal distribution ofLegionellaspecies in the water supply of 20 hospitals in Catalonia, Spain.

Setting:

20 hospitals in Catalonia, an area of 32,000 km2, located in northeast Spain.

Methods:

Environmental cultures of 186 points of potable water supply and 10 cooling towers were performed for the presence ofLegionellaspecies. Following filtration and acid treatment, the samples were seeded in selective MWY (modified Wadowsky Yee)-buffered charcoal yeast extract-a agar. All isolates obtained were characterized microbiologically and genotyped bySfilpulsed-field gel electrophoresis (PFGE).

Results:

73 of 196 water samples, representing 17 of the 20 hospitals included in the study, were positive forLegionella pneumophila(serogroups 1, 2-14, or both). The degree of contamination ranged from 200 to 74,250 colony-forming units/L. Twenty-five chromosomal DNA subtypes were detected by PFGE. A single DNA subtype was identified in 10 hospitals, 2 DNA subtypes were observed in 6 hospitals, and 1 hospital exhibited 3 different DNA subtypes. Each hospital had its ownLegionellaDNA subtype, which was not shared with any other hospitals.

Conclusions:

Legionellawas present in the water of most of the hospitals studied; each such hospital had a unique, dominant chromosomal DNA subtype. The verification of several genomic DNA restriction profiles in such a small geographic area demonstrates the great genetic diversity ofLegionellain the aquatic environment.

Current clinical management of Legionnaires’ disease

Legionella pneumophila is increasingly recognized as a cause of both sporadic and epidemic community-acquired pneumonia. Clinical manifestations of Legionnaires' disease are not specific and current diagnostic scores are of limited use. Urinary antigen detection is an effective test for rapid diagnosis of infection caused by L. pneumophila serogroup 1. Improved outcomes regarding the time to defervescence, development of complications and length of stay, have been recently observed for patients treated with levofloxacin monotherapy. Current case-fatality rates for hospitalized patients with community-acquired Legionella pneumonia are lower than those traditionally reported for this infection. Effective preventive strategies are needed.

Systematic review and metaanalysis: urinary antigen tests for Legionellosis

BACKGROUND

Urinary antigen assays offer simplicity and rapidity in diagnosing Legionnaires' disease, though studies report a range of sensitivities. We conducted a systematic review to assess the test characteristics of Legionella urinary antigen.

METHODS

We searched Medline, Excerpta Medica Database, and bibliographies of retrieved articles. English-language studies were used and included if the absolute number of true-positive, false-negative, true-negative, and false-positive observations were available, and the "gold standards" were described clearly. Two investigators independently reviewed articles and extracted data. Quality was assessed with the Quality Assessment for Diagnostic Accuracy Studies (QUADAS). Sensitivities and specificities were pooled using a random-effects model weighted with the inverse of the SE calculated through the Wald method.

RESULTS

Fifty articles were retrieved for detailed evaluation, and 30 met the inclusion criteria. All but two studies focused on serotype 1 Legionella. Forty assays were reported using six different methodologies, whereas 26 assays used commercial tests, and 14 assays used in-house tests. Study quality was generally low, with average QUADAS scores of 4.4 of a total of 14 points (range, 1 to 9 points). The pooled sensitivity was 0.74 (95% CI, 0.68 to 0.81), and the specificity was 0.991 (95% CI, 0.984 to 0.997). Higher quality studies had lower sensitivity, and there was evidence of publication bias.

CONCLUSIONS

Legionella urinary antigen for serotype 1 appears to have excellent specificity, though modest sensitivity. However, the poor quality of the included studies and the presence of publication bias suggest an overestimation of test performance. High-quality studies are needed.

[Comparison of five commercial assays for the detection of Legionella pneumophila antigens in urine]

OBJECTIVE

Antigenuria detection is the main approach for diagnosing Legionella infections. The aim of this study was to compare 5 commercially available methods for detecting Legionella pneumophila soluble antigens in urine.

METHODS

Seventy-one urine samples were tested, 62 from patients with bacterial infection and 9 from patients with respiratory syncytial virus infection. All samples were assayed for the presence of L. pneumophila by immunoenzymatic (ELISA) (Binax and Bartels), and immunochromatographic (IC) (Binax, SAS and Uni-Gold) methods.

RESULTS

Identical results (35 positive and 17 negative) were obtained by the 5 assays in 52 samples (73.2%). Samples showing discrepant results were classified by the majority criterion, and/or other laboratory results (serology), and/or epidemiological findings. On this basis, 51 samples were ultimately classified as positive, and 20 as negative. Sensitivity values of ELISA-Binax, ELISA-Bartels, IC-Binax, IC-SAS and IC-Uni-Gold were 80.4, 100, 82.4, 86.3, and 70.6%, respectively. Corresponding values for specificity were 90, 95, 100, 95 and 100%.

CONCLUSIONS

The results indicate that the methods compared are all adequate for diagnosing Legionella infection, although some have certain limitations regarding sensitivity.

Pathogen detection: A perspective of traditional methods and biosensors

The detection of pathogenic bacteria is key to the prevention and identification of problems related to health and safety. Legislation is particularly tough in areas such as the food industry, where failure to detect an infection may have terrible consequences. In spite of the real need for obtaining analytical results in the shortest time possible, traditional and standard bacterial detection methods may take up to 7 or 8 days to yield an answer. This is clearly insufficient, and many researchers have recently geared their efforts towards the development of rapid methods. The advent of new technologies, namely biosensors, has brought in new and promising approaches. However, much research and development work is still needed before biosensors become a real and trustworthy alternative. This review not only offers an overview of trends in the area of pathogen detection but it also describes main techniques, traditional methods, and recent developments in the field of pathogen bacteria biosensors.

Value of serological testing for diagnosis of legionellosis in outbreak patients

Serum antibody detection tests and a urine antigen detection technique were compared in samples from 116 patients epidemiologically characterized as belonging to a legionellosis outbreak. Sera were tested by enzyme-linked immunosorbent assays (ELISAs) for immunoglobulin M (IgM) and IgG plus IgM and by immunofluorescent assays (IFAs) for IgG, IgM, IgA, and polyimmunoglobulin using commercial kits (Vircell); concentrated urines were tested with the Binax NOW Legionella test. ELISA for IgM, ELISA for IgG plus IgM, antigenuria detection, and IFA for IgM were able to diagnose 72.3%, 60.5%, 53.3%, and 51.4%, respectively, of patients. Antigenuria was present in 53.8% of first samples, ELISA detected IgM in 29.7%, ELISA detected IgG plus IgM in 7.9%, and IFA detected IgM in 3.9%. Ten antigenuria-negative first samples tested serologically positive, 9 of them to IgM by ELISA. Despite the single source of the samples included in the study, detection of IgM using a sensitive technique such as ELISA seems to be a suitable complement to antigenuria detection for the diagnosis of legionellosis.

Single-run, parallel detection of DNA from three pneumonia-producing bacteria by real-time polymerase chain reaction

A molecular assay for parallel detection of three bacteria, Chlamydia (C.) pneumoniae, Legionella (L.) spp., and Mycoplasma (M.) pneumoniae, in clinical specimens by a set of real-time polymerase chain reactions (PCRs) in a single run was evaluated. Bacterial DNAs were extracted by an automated DNA extraction protocol on the MagNA Pure LC System. Amplification and detection were done by real-time PCR on the LightCycler (LC) instrument. For amplification, specific oligonucleotides derived from the 16s rRNA genes of C. pneumoniae, L. spp., and M. pneumoniae were used. The three assays were complemented with an internal control (IC), a specially designed DNA fragment which contains the specific primer binding sites for the three PCRs. The IC was added to the samples, co-extracted, and co-amplified. Primers and hybridization probes were designed to suit one LC PCR program. LC PCRs were established, detection limits were determined, and clinical samples were tested. The detection limits were found between 5.0 and 0.5 IFU/CFU per PCR reaction for each of the bacteria. A total number of 100 clinical specimens were tested for validation of the molecular assay. Tested samples included 63 bronchoalveolar lavages (BALs) and 37 induced sputa specimens. The internal control was detected in all negative and low-positive samples; no inhibition was found throughout the whole study. Additionally, samples underwent testing by culture for L. spp., and M. pneumoniae; for C. pneumoniae, the serological microimmunofluorescence (MIF) test was used. In conclusion, the developed set of LC PCR assays permits parallel detection of C. pneumoniae, L. spp., and M. pneumoniae in a single LC run. This molecular assay may lead to accurate and early diagnosis of pneumonia produced by these three types of bacteria. The assay proved to be suitable for the high-throughput routine diagnostic laboratory.

Multicenter study of hospital-acquired pneumonia in non-ICU patients

STUDY OBJECTIVE

To know the incidence, epidemiology, etiology, and outcome of hospital-acquired pneumonia (HAP) in non-ICUs adult patients.

SETTING

Twelve Spanish teaching hospitals.

INTERVENTIONS

From April 1999 to November 2000, non-ICU HAP was prospectively studied by active, bimonthly 1-week surveillance. Epidemiologic data, etiology, and evolution of pneumonia were recorded. Blood and sputum cultures and Legionella pneumophila and Streptococcus pneumoniae urinary antigen tests were performed.

RESULTS

We included 186 patients, with complete data available in 165 patients (70.3% male gender; mean age, 63.7 +/- 16.9 years [ +/- SD]) The mean incidence of HAP was 3 +/- 1.4 cases/1,000 hospital admissions. Most patients (64.2%) were in medical wards, had severe underlying diseases (66.6%), and had a hospital stay > 5 days (76.4%). Blood cultures were performed in 139 patients (84.2%), sputum cultures were performed in 89 patients (53.9%), and urinary antigen detection was performed in 123 patients (74.5%). An etiologic diagnosis was obtained in 60 cases (36.4%), and 31 were definitive. The most frequent etiologies were S pneumoniae (16 cases, 14 definitive), L pneumophila (7 cases, 7 definitive), Aspergillus sp (7 cases, 3 definitive), Pseudomonas aeruginosa (7 cases, 2 definitive), and several Enterobacteriaceae (8 cases, 4 definitive). Clinical complications occurred in 52.1% of the cases, and mortality was 26% (13.9% attributed to pneumonia).

CONCLUSIONS

Non-ICU HAP is an important cause of hospital morbidity, observed most frequently in medical wards and elderly patients with severe underlying diseases. In this setting, S pneumoniae and Legionella sp should be considered in addition to other nosocomial pathogens; urinary antigen detection is useful in determining the prevalence of these microorganisms.

Evaluation of a commercial enzyme immunoassay for HIV screening in urine

A cross-sectional study was conducted to evaluate the utility of a commercial enzyme immunoassay (EIA) as a screening test for detecting HIV-1 antibody in urine in a population at risk for HIV infection in Catalonia, Spain. Paired urine and serum samples were collected consecutively from 99 patients who attended two drug-dependency treatment centres and 151 patients who attended a sexually transmitted diseases (STD) clinic in Barcelona. Antibodies against HIV in urine samples were detected using the Calypte HIV-1 Urine EIA (Calypte Biomedical Corporation, Berkeley, CA, USA) and confirmed by urine-based Western blot (WB) analysis. Sera were analysed using Bioelisa HIV-1+2 EIA (Biokit Laboratories, Barcelona, Spain), and the results were verified using serum-based WB analysis. Results of both urine and serum testing were available for 246 of 250 participants. For 52 individuals the results of both urine and serum testing were positive and for five the results were discordant (2 with urine-negative/serum-positive results and 3 with urine-positive/serum-negative results). The respective sensitivity and specificity values obtained for the urine EIA were 100% and 96.2% for intravenous drug users (IDUs) and 80% and 99.3% for persons attending the STD clinic. According to the 1997 UNAIDS/WHO strategy I recommendations, these values are acceptable for surveillance purposes, particularly in populations with a high prevalence of HIV infection.

Comparison of diagnostic sensitivities of three assays (Bartels enzyme immunoassay [EIA], Biotest EIA, and Binax NOW immunochromatographic test) for detection of Legionella pneumophila serogroup 1 antigen in urine

The Bartels enzyme immunoassay (EIA), Biotest EIA, and Binax NOW immunochromatographic test (ICT) urinary antigen kits for the detection of Legionella pneumophila serogroup 1 were compared using 178 frozen urine samples. When nonconcentrated urine samples were used, the sensitivity levels of both enzyme EIAs were significantly higher than the sensitivity level of the ICT (Bartels EIA, 71.3%; Biotest EIA, 65.1%; Binax NOW ICT, 37% [P < 0.001]). After concentration of the urine samples, no significant differences in sensitivity were found among the three tests.

Factors related to persistence of Legionella urinary antigen excretion in patients with legionnaires' disease

The aim of this prospective study was to compare patient characteristics, clinical data, and evolution of Legionella pneumophila pneumonia according to the duration of Legionella urinary antigen excretion. Urine samples from 61 patients with Legionella pneumonia diagnosed by detection of urinary antigen were obtained periodically until urinary antigen could no longer be detected. Cases were divided into two groups based on the duration of urinary antigen excretion: group I (46 patients, <60 days) and group II (15 patients, >or=60 days). Groups were compared for patient characteristics, clinical data, and evolution of pneumonia. Antigen excretion >or=60 days was observed significantly more frequently in immunosuppressed patients ( P=0.001) in whom the time to apyrexia was >72 h ( P=0.002), although only the time to apyrexia remained significant on multivariate analysis ( P=0.006). In conclusion, the duration of Legionella urinary antigen excretion was <60 days in most patients but was longer in immunosuppressed patients with a longer time to defervescence of fever.

Legionella and Legionnaires' disease: 25 years of investigation

There is still a low level of clinical awareness regarding Legionnaires' disease 25 years after it was first detected. The causative agents, legionellae, are freshwater bacteria with a fascinating ecology. These bacteria are intracellular pathogens of freshwater protozoa and utilize a similar mechanism to infect human phagocytic cells. There have been major advances in delineating the pathogenesis of legionellae through the identification of genes which allow the organism to bypass the endocytic pathways of both protozoan and human cells. Other bacteria that may share this novel infectious process are Coxiella burnetti and Brucella spp. More than 40 species and numerous serogroups of legionellae have been identified. Most diagnostic tests are directed at the species that causes most of the reported human cases of legionellosis, L. pneumophila serogroup 1. For this reason, information on the incidence of human respiratory disease attributable to other species and serogroups of legionellae is lacking. Improvements in diagnostic tests such as the urine antigen assay have inadvertently caused a decrease in the use of culture to detect infection, resulting in incomplete surveillance for legionellosis. Large, focal outbreaks of Legionnaires' disease continue to occur worldwide, and there is a critical need for surveillance for travel-related legionellosis in the United States. There is optimism that newly developed guidelines and water treatment practices can greatly reduce the incidence of this preventable illness.

Legionella and Legionnaires' disease: 25 years of investigation

There is still a low level of clinical awareness regarding Legionnaires' disease 25 years after it was first detected. The causative agents, legionellae, are freshwater bacteria with a fascinating ecology. These bacteria are intracellular pathogens of freshwater protozoa and utilize a similar mechanism to infect human phagocytic cells. There have been major advances in delineating the pathogenesis of legionellae through the identification of genes which allow the organism to bypass the endocytic pathways of both protozoan and human cells. Other bacteria that may share this novel infectious process are Coxiella burnetti and Brucella spp. More than 40 species and numerous serogroups of legionellae have been identified. Most diagnostic tests are directed at the species that causes most of the reported human cases of legionellosis, L. pneumophila serogroup 1. For this reason, information on the incidence of human respiratory disease attributable to other species and serogroups of legionellae is lacking. Improvements in diagnostic tests such as the urine antigen assay have inadvertently caused a decrease in the use of culture to detect infection, resulting in incomplete surveillance for legionellosis. Large, focal outbreaks of Legionnaires' disease continue to occur worldwide, and there is a critical need for surveillance for travel-related legionellosis in the United States. There is optimism that newly developed guidelines and water treatment practices can greatly reduce the incidence of this preventable illness.

[Evaluation of a new ELISA (Bartels) for detection of Legionella pneumophila antigen in urine]

BACKGROUND

Detection of Legionella pneumophila soluble antigens allows rapid diagnosis of pneumonia caused by these bacteria. A new ELISA (Bartels) for antigenuria detection has recently been commercialized. We compared the new ELISA with another well-established ELISA (Binax).

METHODS

To evaluate ELISA-Bartels (Legionella Urinary Antigen, Intracel, Issaquah, Washington, United States), urine samples previously characterized by ELISA Binax (Legionella Urinary Antigen Enzyme Immunoassay Kit, Binax, Portland, Maine, United States) were used. Samples came from Legionella outbreaks (n = 48), from sporadic legionellosis (n = 38), and from children with viral pneumonia (n = 21). Samples from the External Quality Control of Legionella of the European Working Group on Legionella Infections (n = 102) were also tested. Of the samples analyzed, 109 were positive in ELISA-Binax, 2 were equivocal and 98 were negative. Samples showing equivocal results were excluded from the analysis.

RESULTS

The sensitivity of ELISA-Bartels in comparison with that of ELISA-Binax was 98.2% (107/109) and specificity was 82.7% (81/98). In the 17 samples that were positive in ELISA-Bartels and negative in ELISA-Binax, 10 were positive in ELISA-Binax after concentration by selective ultrafiltration and 6 further cases showed serology indicating or compatible with recent Legionella infection and were thus classified as true positives.

CONCLUSIONS

ELISA-Bartels showed good sensitivity and specificity. Sensitivity was even higher than that of ELISA-Binax. Thus, we consider it to be an appropriate method for diagnosis of Legionella pneumonia.

Presence and chromosomal subtyping of Legionella species in potable water systems in 20 hospitals of Catalonia, Spain

OBJECTIVE

To investigate the presence and clonal distribution of Legionella species in the water supply of 20 hospitals in Catalonia, Spain.

SETTING

20 hospitals in Catalonia, an area of 32,000 km2, located in northeast Spain.

METHODS

Environmental cultures of 186 points of potable water supply and 10 cooling towers were performed for the presence of Legionella species. Following filtration and acid treatment, the samples were seeded in selective MWY (modified Wadowsky Yee)-buffered charcoal yeast extract-alpha agar. All isolates obtained were characterized microbiologically and genotyped by SfiI pulsed-field gel electrophoresis (PFGE).

RESULTS

73 of 196 water samples, representing 17 of the 20 hospitals included in the study, were positive for Legionella pneumophila (serogroups 1, 2-14, or both). The degree of contamination ranged from 200 to 74,250 colony-forming units/L. Twenty-five chromosomal DNA subtypes were detected by PFGE. A single DNA subtype was identified in 10 hospitals, 2 DNA subtypes were observed in 6 hospitals, and 1 hospital exhibited 3 different DNA subtypes. Each hospital had its own Legionella DNA subtype, which was not shared with any other hospitals.

CONCLUSIONS

Legionella was present in the water of most of the hospitals studied; each such hospital had a unique, dominant chromosomal DNA subtype. The verification of several genomic DNA restriction profiles in such a small geographic area demonstrates the great genetic diversity of Legionella in the aquatic environment.

[The role of the clinical microbiology laboratory during the outbreak of Legionella spp. in the municipality of Alcoy: the effectiveness of the different diagnosis methods]

BACKGROUND

The effectiveness of the different laboratory test methods to diagnose Legionella spp. in clinical specimens varies according to the epidemiological context. In this study, the usefulness of the laboratory methods used for an outbreak that occurred in the municipality of Alcoy (Alicante, Spain) are evaluated.

MATERIALS AND METHODS

222 community-acquired cases of infection caused by Legionella pneumophila serogroup 1, subtype Pontiac-Knoxville, genotypes I and II were studied, that had been diagnosed by the Microbiology laboratory from January 1999 to December 2000, corresponding to patients residing in the municipality of Alcoy (Alicante). The methods used were direct antigen detection in respiratory specimens by immunoflurescence, direct antigen detection in urine, cultures and serology.

RESULTS

The detection of the antigen in urine diagnosed 201 cases (90,5%). Direct immunofluorescence provided a high number of false positives (n=24). A culture was essential to confirm the etiology of the outbreak (25 sputum) strains from 22 patients). Serology complemented the other methods and helped to retrospectively diagnose 21 patients (9%) when the other tests were not carried out or when they provided negative results.

CONCLUSIONS

A rapid diagnosis is essential to evaluate the patients and to control epidemical outbreaks, and the detection of the urinary antigen is very useful, but should be complemented with other methods. The culture of the respiratory specimens and the subsequent typing of the strains means that the etiology can be established with certainty and this helps to determine the source(s) of the infection. Serology complemented the diagnosis in 9% of the cases.

Direct detection of Legionella species from bronchoalveolar lavage and open lung biopsy specimens: comparison of LightCycler PCR, in situ hybridization, direct fluorescence antigen detection, and culture

We developed a rapid thermocycling, real-time detection (also known as real-time PCR) method for the detection of Legionella species directly from clinical specimens. This method uses the LightCycler (Roche Molecular Biochemicals, Indianapolis, Ind.) and requires approximately 1 to 2 h to perform. Both a Legionella genus PCR assay and Legionella pneumophila species-specific PCR assay were designed. A total of 43 archived specimens from 35 patients were evaluated, including 19 bronchoalveolar lavage (BAL) specimens and 24 formalin-fixed, paraffin-embedded open lung biopsy specimens. Twenty-five of the specimens were culture-positive for Legionella (9 BAL specimens and 16 tissue specimens). BAL specimens were tested by LightCycler PCR (LC-PCR) methods and by a direct fluorescent antibody (DFA) assay, which detects L. pneumophila serogroups 1 to 6 and several other Legionella species. Tissue sections were tested by the two LC-PCR methods, by DFA, by an in situ hybridization (ISH) assay, specifically designed to detect L. pneumophila, and by Warthin-Starry (WS) staining. The results were compared to the "gold standard" method of bacterial culture. With BAL specimens the following assays yielded the indicated sensitivities and specificities, respectively: Legionella genus detection by Legionella genus LC-PCR, 100 and 100%; Legionella genus detection by DFA assay, 33 and 100%; and L. pneumophila detection by L. pneumophila species-specific LC-PCR, 100 and 100%. With open lung biopsy specimens the following assays yielded the indicated sensitivities and specificities, respectively: Legionella genus detection by LC-PCR 68.8 and 100%; Legionella genus detection by DFA assay, 44 and 100%; Legionella genus detection by WS staining, 63 and 100%; L. pneumophila species-specific detection by LC-PCR, 17 and 100%; and L. pneumophila species-specific detection by ISH, 100 and 100%. The analytical sensitivity of both LC-PCR assays was <10 CFU/reaction. LC-PCR is a reliable method for the direct detection of Legionella species from BAL specimens. The Legionella genus LC-PCR assay could be performed initially; if positive, L. pneumophila species-specific LC-PCR could then be performed (if species differentiation is desired). The speed with which the LC-PCR procedure can be performed offers significant advantages over both culture-based methods and conventional PCR techniques. In contrast, for the methods evaluated, culture was the best for detecting multiple Legionella species in lung tissue. WS staining, Legionella genus LC-PCR, and L. pneumophila species-specific ISH were useful as rapid tests with lung tissue.

Comparison of the Binax Legionella urinary antigen enzyme immunoassay (EIA) with the Biotest Legionella Urin antigen EIA for detection of Legionella antigen in both concentrated and nonconcentrated urine samples

We evaluated a newly commercial enzyme immunoassay (EIA) (Biotest Legionella Urin Antigen EIA; Biotest AG, Dreieich, Germany) for detection of antigens of all Legionella pneumophila serogroups with a relatively wide spectrum of cross-reactivity as well as antigens of other Legionella spp. by comparing its sensitivity and specificity with those of an EIA for detection of L. pneumophila serogroup 1 antigen (Legionella urinary antigen EIA; Binax, Portland, Maine). Both tests were performed with both concentrated and nonconcentrated urine samples. We also evaluated the capabilities of both EIAs to detect extracted soluble antigens of American Type Culture Collection (ATCC) Legionella strains (L. pneumophila serogroups 1 to 14, L. bozemanii, and L. longbeachae). The sensitivity of the Biotest EIA was 66.66% in nonconcentrated urine and 86.66% in concentrated urine. The sensitivity of the Binax EIA was 63.76% and 88.88% in nonconcentrated and concentrated urine, respectively. The specificity was 100% in nonconcentrated and concentrated urine for both assays. The Binax EIA and Biotest EIA detected extracted soluble antigens of L. pneumophila serogroups 1 to 14 and L. bozemanii ATCC strains. The cross-reactions observed with the Binax EIA were probably due to common epitopes directly related to lipopolysaccharide. Further studies are required to determine the usefulness of the Binax EIA for detection of urinary antigens from Legionella species and serogroups other than L. pneumophila serogroup 1. The Biotest EIA proved to be as rapid, sensitive, and specific as the Binax EIA for the diagnosis of legionellosis. Concentration of antigen present in urine increased the sensitivities of both techniques with no reduction in specificity.

Comparative study of the clinical presentation of Legionella pneumonia and other community-acquired pneumonias

The aim of this study was to compare the clinical, biological, and radiologic features of presentation in the emergency ward of community-acquired pneumonia (CAP) by Legionella pneumophila (LP) and other community-acquired bacterial pneumonias to help in early diagnosis of CAP by LP. Three hundred ninety-two patients with CAP were studied prospectively in the emergency department of a 600-bed university hospital. Univariate and multivariate analyses were performed to compare epidemiologic and demographic data and clinical, analytical, and radiologic features of presentation in 48 patients with CAP by LP and 125 patients with CAP by other bacterial etiology (68 by Streptococcus pneumoniae, 41 by Chlamydia pneumoniae, 5 by Mycoplasma pneumoniae, 4 by Coxiella burnetii, 3 by Pseudomonas aeruginosa, 2 by Haemophilus influenzae, and 2 by Nocardia species. Univariate analysis showed that CAP by LP was more frequent in middle-aged, male healthy (but alcohol drinking) patients than CAP by other etiology. Moreover, the lack of response to previous beta-lactamic drugs, headache, diarrhea, severe hyponatremia, and elevation in serum creatine kinase (CK) levels on presentation were more frequent in CAP by LP, while cough, expectoration, and thoracic pain were more frequent in CAP by other bacterial etiology. However, multivariate analysis only confirmed these differences with respect to lack of underlying disease, diarrhea, and elevation in the CK level. We conclude that detailed analysis of features of presentation of CAP allows suspicion of Legionnaire's disease in the emergency department. The initiation of antibiotic treatment, including a macrolide, and the performance of rapid diagnostic techniques are mandatory in these cases.