Antigen detection for the rapid diagnosis of mycoplasma and Legionella pneumonia

Legionella pneumonia associated with adult respiratory distress syndrome caused by Legionella pneumophila serogroup 3

A 68-year-old man developed pneumonia 2 days after nearly drowning in a bathtub of a hot spring spa. Chest radiography revealed bilateral consolidation shadows associated with adult respiratory distress syndrome. Initial treatment with antibiotics and pulse therapy with methylprednisolone was not effective. The patient died on the 4th hospital day. A urinary antigen test for Legionella was positive. Legionella pneumophila serogroup 3 was recovered from an intratracheal specimen. The same serotype of Legionella was isolated from the hot spring water. Restriction enzyme analysis by pulse-field gel electrophoresis revealed identical restriction fragments. We conclude that the water at the hot spring spa could have been the source of infection.

Infection due to Legionella species other than L. pneumophila

In addition to Legionella pneumophila, 19 Legionella species have been documented as human pathogens on the basis of their isolation from clinical material. Like L. pneumophila, other Legionella species are inhabitants of natural and man-made aqueous environments. The major clinical manifestation of infection due to Legionella species is pneumonia, although nonpneumonic legionellosis (Pontiac fever) and extrapulmonary infection may occur. The majority of confirmed infections involving non-pneumophila Legionella species have occurred in immunosuppressed patients. Definitive diagnosis requires culture on selective media. Fluoroquinolones and newer macrolides are effective therapy. A number of nosocomial cases have occurred in association with colonization of hospital water systems; elimination of Legionella species from such systems prevents their transmission to susceptible patients. It is likely that many cases of both community-acquired and nosocomial Legionella infection remain undiagnosed. Application of appropriate culture methodology to the etiologic diagnosis of pneumonia is needed to further define the role of these organisms in disease in humans.

Rapid diagnosis of Legionella pneumophila serogroup 1 infection with the Binax enzyme immunoassay urinary antigen test

The Binax legionella urinary antigen (LUA) enzyme immunoassay (Binax, Portland, Maine) was evaluated in 159 patients with suspected or proven legionellosis and 209 controls. A positive LUA test was found in 37% of patients with suspected legionellosis overall and in 83% of those with proven Legionella pneumophila serogroup 1 infection. The sensitivity of the LUA test was significantly greater than that of the direct fluorescent-antigen test (83 versus 42%; P < 0.0001) but not significantly different from that of culture (85%) or serology (91%); specificity was at least 99.5%.

Outbreak of Legionnaires' disease among cruise ship passengers exposed to a contaminated whirlpool spa

BACKGROUND

Outbreaks of travel-related Legionnaires' disease present a public-health challenge since rapid, sensitive, and specific diagnostic tests are not widely used and because detection of clusters of disease among travellers is difficult. We report an outbreak of Legionnaires' disease among cruise ship passengers that occurred in April, 1994, but that went unrecognised until July, 1994.

METHODS

After rapid diagnosis of Legionnaires' disease in three passengers by urine antigen testing, we searched for additional cases of either confirmed (laboratory evidence of infection) or probable Legionnaires' disease (pneumonia of undetermined cause). A case-control study was conducted to compare exposures and activities on the ship and in ports of call between each case-passenger and two or three matched control-passengers. Water samples from the ship, from sites on Bermuda, and from the ship's water source in New York City were cultured for legionellae and examined with PCR.

FINDINGS

50 passengers with Legionnaires' disease (16 confirmed, 34 probable) were identified from nine cruises embarking between April 30 and July 9, 1994. Exposure to whirlpool spas was strongly associated with disease (odds ratio 16.2, 95% Cl 2.8-351:7); risk of acquiring Legionnaires' disease increased by 64% (95% Cl 12-140) for every hour spent in the spa water. Passengers spending time around the whirlpool spas, but not in the water, were also significantly more likely to have acquired infection. Legionella pneumophila serogroup 1 was isolated only from the sand filter in the ship's whirlpool spa. This isolate matched a clinical isolate from the respiratory secretions of a case-passenger as judged by monoclonal antibody subtyping and by arbitrarily primed PCR.

INTERPRETATION

This investigation shows the benefit of obtaining a recent travel history, the usefulness or urine antigen testing for rapid diagnosis of legionella infection, and the need for improved surveillance for travel-related Legionnaires' disease. New strategies for whirlpool spa maintenance and decontamination may help to minimise transmission of legionellae from these aerosol-producing devices.

Diagnosis of Legionnaires' disease by radioimmunoassay of Legionella antigen in pleural fluid

We describe a case of culture-proven Legionnaires' disease (serogroup 1) in which a rapid diagnosis was made by detection of Legionella antigen in pleural fluid by use of the Binax radioimmunoassay for urine.

Evaluation of the L-CLONE Legionella pneumophila Serogroup 1 Urine Antigen Latex Test

The purpose of this study was to evaluate the L-CLONE Legionella pneumophila Serogroup 1 Urine Antigen Latex Test (Access Medical Systems, Inc., Branford, Conn.) for detection of Legionella antigen in urine. A total of 481 frozen urine samples previously tested by an in-house solid-phase radioimmunoassay (RIA) was thawed and retested by using L-CLONE. Included in this sample were 140 RIA-positive samples from culture-positive or serologically confirmed cases of legionellosis and 341 RIA-negative samples from patients with non-Legionella respiratory disease or bacteriuria. The original RIA test result was accepted as the true value. L-CLONE correctly identified 76 of 140 (54%) known positive samples. False-negative results could not be attributed to a low Legionella antigen concentration or to a Legionella antigen subgroup. L-CLONE correctly identified 252 of 341 (74%) known negative samples. False-positive results were experienced in all groups of negative samples, regardless of the patients' underlying diseases. A total of 141 fresh urine samples was tested; all were Legionella antigen negative by RIA. L-CLONE provided 86% specificity. The sensitivity of the L-CLONE in testing fresh urine samples could not be evaluated because of the lack of Legionella antigen RIA-positive samples.

Use of DNA probes for the diagnosis of infections caused by Mycoplasma pneumoniae and legionellae--a review

Specific DNA probes have been made for both M. pneumoniae and Legionella species. Dot blot methods have been used in research laboratories to test culture isolates of both organisms, and also to test animal tissues with a L. pneumophila-specific probe. Commercial kits are also available for direct specimen testing for these two organisms. The commercial kits are made by a single manufacturer, Gen-Probe, Inc. (San Diego, CA), and use a novel in-solution rapid hybridization assay, using 125I-labeled cDNA to rRNAs of the organisms. The Gen-Probe M. pneumoniae probe appears to be 80% to 100% sensitive, and 97% to 100% specific, based on analysis of two clinical studies using positive culture as the diagnostic criterion. The Gen-Probe legionella probe appears to be 33% to 71% sensitive (mean 57%), and 98.9% to 99.7% specific (mean 99.7%), based on analysis of four prospective clinical studies, using positive culture as the definition of disease, with a total sample size of 3,243 patients, 49 of which were culture-positive. Both Gen-Probe direct tests appear to be clinically useful, although the poor performance of the legionella test in one major university laboratory, and the expense of performing these tests, mandate that thorough evaluations be carried out in each laboratory anticipating using the test. Culture must always be performed for legionella whether or not the DNA probe test is used. It is likely that the use of the M. pneumoniae kit would greatly speed diagnosis, but whether this would alter medical practice or result in lower morbidity and health care costs is unknown.

Rapid etiological diagnosis of pneumonia in young men

The major findings and conclusions of the present study are: 1. Evidence of the etiology of the pneumonia was established in 86% of 106 young men with pneumonia. Pneumococcus was the most common etiologic agent; it was detected definitely in 30% of the pneumonia patients, and possibly in another 20%, by blood culture, sputum culture, antigen detection, and serological methods. 2. Pneumococcal antigen detection from purulent pretreatment sputum samples was the best rapid diagnostic method for pneumococcus; it was capable of identifying 90% of the pneumococcal pneumonias definite by our criteria, whereas sputum Gram stain was positive in 65% of these. 3. Detection of adenoviral antigens from nasopharyngeal specimens (NPS) by EIA or IF method or adenovirus DNA by HYB method showed good specificity but a somewhat lower sensitivity than did adenovirus isolation from NPS. 4. Adenovirus antigens and DNA can be demonstrated also from sputum specimens. 5. EIA is slightly superior to the CF method in detecting antibody responses to adenovirus, but the detection of different antibody classes offers no additional diagnostic possibilities. 6. Isolation of Mycoplasma pneumoniae from bronchoalveolar fluid in pneumonia patients is a specific and sensitive method in the diagnosis of mycoplasmal pneumonia. 7. It seems possible to differentiate by clinical signs and symptoms and by high CRP (over 85mg/1) and WBC (over 10 x 10(9)/1) values pneumococcal pneumonias from viral, mycoplasmal and mixed pneumonias and from upper respiratory infections. Moderately elevated CRP values were observed in adenoviral (Mean 50 mg/1) and in mycoplasma (mean 59 mg/l) pneumonias, as well as in MRI (mean 44 mg/l).

Nosocomial Legionnaires' disease: a global perspective

Nosocomial Legionnaires' disease is a worldwide problem. The lack of prospective surveys using sensitive diagnostic means, such as culture, has resulted in ignorance about the exact magnitude of the problem except at a handful of individual hospitals. Contaminated hospital hot water systems, cooling towers, and non-sterile tap water used for respiratory therapy may all cause disease. Culture diagnosis is the preferred method of case ascertainment, and provides bacterial isolates which can be used to implicate specific environmental sites using molecular epidemiologic techniques. Environmental culture surveys, done in the absence of known disease, are probably not indicated, but there remains concern that wards housing very high risk patients should be legionella-free. Use of monoclonal antibody typing of environmental isolates of L. pneumophila serogroup 1 may be useful in this regard, as it can possibly detect strains most likely to cause disease. Control of nosocomial disease requires centralized management and consultation by expert engineers, epidemiologists, and microbiologists.

Laboratory diagnosis of infections caused by legionellae

Legionnaires' disease can be diagnosed by detection of antibody to the organism or by direct detection of the bacterium and/or its products using immunological means, culture or a DNA probe. Culture isolation, still the most specific and sensitive test, can be done with sputum samples if proper selective techniques are used. Antibody detection is more suited for epidemiological purposes than individual cases. It has been overused to the exclusion of more specific and rapid methods, such as culture and other means of bacterial detection. Immunofluorescent microscopy remains an important tool in diagnosis, although urinary antigen detection and DNA probes are promising alternative tests. For optimal sensitivity, culture must be performed, regardless of which test is used.

Broad-spectrum enzyme-linked immunosorbent assay for detection of Legionella soluble antigens

An enzyme-linked immunosorbent assay (ELISA) was developed which detected soluble antigens from culture extracts of Legionella pneumophila serogroups 1 to 8, L. micdadei, L. bozemanii serogroups 1 and 2, L. dumoffii, L. gormanii, L. longbeachae serogroups 1 and 2, L. wadsworthii, L. oakridgensis, L. anisa, L. feeleii serogroup 1, and L. jordanis. The assay was approximately 10-fold more sensitive for the eight L. pneumophila serogroups than for the other Legionella species tested. The ELISA detected Legionella antigens in the urine specimens of 25 of 35 patients with L. pneumophila serogroup 1, 3, 4, 6, and 8; L. micdadei; and L. longbeachae serogroup 1 infections. None of the 334 urine specimens from patients with either non-Legionella pneumonia or urinary tract infections was positive. For 10 patients from whom sequential urine specimens were available, Legionella antigens were not detectable from 7 to 19 days after laboratory diagnosis. Test sensitivity was not affected by heavy bacterial contamination. This ELISA offers the detection of a broad spectrum of Legionella antigens by a single test.