Rapid diagnosis of Legionnaires' disease by direct immunofluorescent staining.

A blind reading of direct immunofluorescent staining of sputum smears was positive in five of 21 patients with Legionnaires' disease and none of 47 control patients. Positive slides showed from eight organisms per smear (one slide) to 20 to 100 organisms per oil-immersion (magnification, 100) field (three slides). Two of the positive specimens were obtained through an endotracheal tube, one at bronchoscopy, and the other positive slides were from expectorated specimens. In addition, two open-lung biopsies and a bronchial lavage sediment from three confirmed cases of Legionnaires' disease were positive by direct immunofluorescent staining for Legionnaires' disease bacterium.     

Legionnaires' disease: respiratory infections caused by Legionella bacteria

This article provides a review of Legionnaire's Disease, a bacterial pneumonia caused by Legionella species, and of Pontiac Fever, the flu-like illness caused by these microorganisms. The authors draw on their personal experience with major human outbreaks of Legionnaire's Disease and with animal models of Legionella pneumonia. Emphasis is placed on the sources in nature from which legionellosis is acquired, the means of dissemination of bacteria, the epidemiology of human infections, the pathogenetic mechanisms of disease and host defense, the clinical manifestations, and the treatment.     

Pathology of Legionnaires' disease.

The acute lesion in Legionnaires' disease pneumonia is an acute fibrinopurulent bronchopneumonia in which the alveoli are filled with many neutrophils and macrophages and abundant fibrin. There is only slight necrosis. Although characteristic, the lesion is not specific for this agent. However, the association with this lesion of myriad small pleomorphic rods, which stain well with Dieterle's silver-impregnation method but poorly or not at all with Gram-type stains, is uncommon except in Legionnaires' disease pneumonia. Final diagnosis requires isolation of the organism or immunofluorescent studies of the tissue, sera or both. The full spectrum of the pneumonia is not known, but organization has been reported once. No definite anatomic correlate for the extrathoracic manifestations of Legionnaires' disease has been identified nor has the organism been found at extrathoracic sites.     

Epidemiology of Legionnaires' disease.

Ten recorded epidemics of Legionnaires' disease are reviewed to gain a working perspective on the epidemiology of the disease. Salient features have included a summer-fall seasonality, a male predominance that may largely reflect increased exposure risk among men, and a striking absence of person-to-person spread. That the disease is spread primarily via the airborne route is well established; air-treatment and air-conditioning equipment has been implicated as the amplification and delivery system in four epidemics. Soils and excavation sites have been suggested as sources of the organism in at least one recorded epidemic. Evidence to date suggests that the Legionnaires' disease bacterium may be widespread in nature. More complete epidemiologic understanding must await development of improved microbiologic and immunologic tests.     

Lessons from Legionnaires' disease.

In July 1976 a pneumonialike epidemic from a previously unrecognized microorganism erupted among Legionnaires who had attended a meeting in Philadelphia. There were an estimated 182 cases, in which 29 patients died. Among other things the episodes shows that even in a medically sophisticated industrialized nation, a bacterical pathogen can produce a small epidemic and defy identification for almost 6 months. One historical implication of the event is the need to consider the possibility of a return of large-scale epidemic disease rivaling the sweeps of bubonic plague in fourteenth-century Europe. Such epidemics could occur through any of a variety of microorganismic mechanisms recognized as operating at the present time. It is suggested that humans would react to such a disaster much as their progenitors did centuries ago.     

Legionnaires' disease antigen detected by enzyme-linked immunosorbent assay.

An enzyme-linked immunosorbent assay method has been developed for the rapid detection of antigen from clinical specimens such as urine and sputum. Preliminary evidence suggests that the antigen is present and can be detected in the sputum and possibly urine of patients with Legionnaires' disease. Patients not harboring the Legionnaires' disease bacterium have been uniformly negative to date.     

Microbiology of Legionnaires' disease bacterium.

Legionnaires' disease bacterium in tissue does not readily react with the Gram stain but can be seen by other stains and direct immunofluorescence. It is a slow-growing, aerobic, gram-negative rod that can be cultivated over a narrow temperature range on Mueller-Hinton agar supplemented either with complex biological mixtures or certain ferric salts and cysteine. The bacterium produces unique, branched-chain fatty acids, catalase, oxidase (weakly), and gelatinase and uses starch while ignoring other carbohydrates. Pigment production is related to tyrosine in the medium. In-vitro studies suggest susceptibility to all antibiotics except vancomycin, but a class 1 beta-lactamase has been demonstrated. Analysis of DNA confirmed the unrelatedness of this bacterium to previously recognized prokaryotes. Diagnosis of the disease has depended largely on serologic test findings and the demonstration of the bacterium in tissue and, occasionally, on isolation. Additional, simpler, and more rapid diagnostic tests should soon be available.     

Radiographic features of Legionnaires' disease.

Serial chest radiographs of 35 patients with confirmed Legionnaires' disease were evaluated. A unilateral, unilobar alveolar infiltrate was, in general, the initial radiographic finding. Progression to consolidation or to new areas of involvement was typical. Every lobe was involved, but lower lobe involvement was most common. Pleural effusion was often present. Cavitation was not seen. Radiographic progression for several days following institution of therapy, and despite clinical response, was noted. In patients who survived, radiographic improvement of abnormalities was usually apparent within two weeks of therapy. Aradiographic spectrum exists and, although many features are typical, no single feature is pathognomonic.     

Legionnaires' disease. A sporadic case.

A patient with Legionnaires' disease developed consolidated pneumonia with severe hypoxemia and mental confusion; his condition improved with therapy with positive end-expiratory pressure, steroids, and chloramphenicol. The retrospective diagnosis was made by a fourfold rise in indirect fluorescent antibody titers. The chest x-ray films showed bilateral alveolar infiltrates and air bronchograms.     

Legionella spp. and Legionnaires' disease

Infection with Legionella spp. is an important cause of community- and hospital-acquired pneumonia, occurring both sporadically and in outbreaks. Infection with Legionella spp. ranks among the three most common causes of severe pneumonia in the community setting, and is isolated in 1-40% of cases of hospital-acquired pneumonia. There are no clinical features unique to Legionnaires' disease. Macrolides and fluoroquinolones are the most widely used drugs in treatment. The availability of a good diagnostic repertoire, suitable for accurately diagnosing LD, constitutes the basis for the early recognition and treatment of the individual patient as well as for effective measures for prevention and control. This review summarizes the available information regarding the microbiology, clinical presentation, diagnosis and treatment of LD, with an emphasis on the laboratory diagnosis of infection with Legionella spp.     

Legionnaires' disease and the traveller.

Respiratory illness occurred in members of a "package tour" to Benidorm, Spain, in 1973. Three of the tourists died with similar pneumonic illnesses, and 86 other travellers who had stayed at the same hotel also had respiratory illnesses. After the organism associated with the epidemic of Legionnaires' disease in Philadelphia 3 years later was identified, sera from patients involved with the "Benidorm episode" were tested. Evidence of infection with the Legionnaires' disease bacterium was obtained from sera from three of the patients who had died and from sera of two of the surviving tourists. Six of 16 members of the staff of the hotel involved had elevated titres to the LD bacterium, suggesting that there may be persistent or recurrent activity in a particular building or locality over a period of years. Surveys of travellers returning to Scotland have shown a large amount of illness, and studies are being conducted to determine the proportion caused by Legionnaires' disease.     

Legionnaires' disease presenting with empyema.

Legionnaire's disease presenting as empyema has not been previously described, although pleural effusions are not uncommon. A 56-year-old woman had a ten-day history of pleuritic chest pain and a large loculated empyema. Legionnaires' disease was documented by serum indirect fluorescent antibody studies.     

Rapid definitive diagnosis of Legionnaires' disease.

We describe a sporadic case of Legionnaires' disease in which the diagnosis was made by direct immunofluorescence of material obtained by percutaneous aspiration of the involved lung via a needle. Employment of this technique among selected patients with suspected Legionnaires' disease would provide for more rapid diagnosis and more prompt initiation of definitive therapy for some patients.     

The Vermont epidemic of Legionnaires' disease.

Sixty-nine laboratory-documented cases of Legionnaires' disease occurred in Vermont between 1 May and 31 December 1977. Clinical manifestations were similar to those in the 1976 Philadelphia epidemic. Case-control studies suggested that Legionnaires' disease patients were more likely to present with headache or diarrhea than were patients with pneumonia of presumed nonbacterial cause. The case-fatality ratio for patients treated with erythromycin was 4%, compared with 17% in patients not treated with erythromycin. Thirteen patients had been hospitalized throughout the 10 days preceding onset of illness, equaling the maximal known incubation period. This suggests either acquisition or reactivation of infection in the hospital. However, even during the week of peak disease activity, cases occurred in patients with no recent hospital contact. The only community factor possibly associated with acquisition was home air conditioning. This prevalence of seroreactivity to the Legionnaires' disease bacterium in various community populations was as high as 26%, suggesting a possible endemic area.