Legionnaires' disease in pneumonia patients in Iowa. A retrospective seroepidemiologic study, 1972-1977

Nosocomial Legionnaire's disease in a children's hospital

BACKGROUND

Only a few cases of nosocomial Legionella sp. infection have been reported in children. We report the clinical and epidemiologic data of five nosocomial legionellosis cases that occurred in the Pediatric Nephrology Service between August, 1994, and December, 1998, and the control measures adopted.

METHODS

The Hospital Materno-Infantil Vall d'Hebron, Barcelona, is a 407-bed tertiary care hospital. The pediatric kidney transplant unit has three isolated beds in the same ward within the Pediatric Nephrology Service. Diagnostic workup to establish Legionella pneumophila infection included culture, fluorescent antibody and serologic studies. Macrorestriction analysis of genomic DNA was used as epidemiologic markers of the isolated strains.

RESULTS

In May, 1996, a case of L. pneumophila serogroup 6 pneumonia was identified in a 19-year-old youth who had received a kidney transplant 16 days earlier. Retrospective and prospective analysis of legionellosis cases diagnosed at our center up to August, 1994, yielded four additional cases. Four patients had had a kidney transplant and were receiving immunosuppressive therapy, and the fifth had been diagnosed with systemic lupus erythematosus with renal involvement. L. pneumophila serogroup 6 was isolated in bronchial secretions in four cases; in the fifth patient the diagnosis was made by serology. L. pneumophila serogroup 6 was isolated from potable water of the hospital. Molecular epidemiologic methods revealed the identity of the environmental and clinical isolates. Showering was implicated as the most feasible means of exposure to contaminated water.

CONCLUSIONS

Nosocomial legionellosis, albeit rare in children, should be considered in the differential diagnosis of pneumonias, particularly in immunosuppressed children, because the fatality rate may be high without early diagnosis and treatment.

Post-infectious encephalomyelitis associated with Mycoplasma pneumoniae and Legionella pneumophila infection

A case of severe acute encephalomyelitis associated with a serological diagnosis of both Mycoplasma pneumoniae and Legionella pneumophila infection is reported. Serological co-positivity between these two pathogens has been reported previously, and has, in general, been attributed to cross-reactivity. This is the first documented case of co-infection using more sensitive and specific serological techniques. The potential significance of these findings is discussed in the context of the considerable problems in the interpretation of serological data.

Legionella pneumophila. A cause of severe community-acquired pneumonia

In a prospective study of community-acquired pneumonias, 30 patients were diagnosed with Legionnaires' disease in 15 months. Clinical, laboratory and radiologic features of these patients are reviewed and compared with those who have pneumococcal pneumonia. Alcoholism, history of smoking, previous antimicrobial therapy, gastrointestinal and neurologic manifestations, elevations of serum transaminases, alkaline phosphatase and creatinine levels were more frequent in pneumonia due to Legionella pneumophila than in pneumococcal pneumonia. The presence of respiratory failure and radiologic progression were common findings that suggested L pneumophila as the etiologic agent of a community-acquired pneumonia. Development of respiratory failure was associated with involvement of several lobes and isolation of L pneumophila in any specimen. In 21 of 30 patients with Legionnaires' disease, L pneumophila was isolated from respiratory specimens. Overall mortality was 10 percent, but it increased to 27 percent in patients not treated with erythromycin initially.

Prevalance of antibodies to 15 antigens of Legionellaceae in patients with community-acquired pneumonia

Sera from 252 patients with community-acquired pneumonia were examined for the presence of antibodies to 15 antigens of 7 Legionella spp. by indirect immunofluorescent antibody testing. The sera had been collected as part of the British Thoracic Society/Public Health Laboratory Service study of community-acquired pneumonia in adults. We also examined sera from 20 patients with gram-negative sepsis. Using a limited range of antigens of L. pneumophila, nine cases of legionellosis were diagnosed in the original study. However, using antigens to other Legionella spp., we identified two further cases, caused by L. micdadei and L. gormanii respectively. Twenty-six other patients had titres of 16 or 32 to one or more antigens, most commonly L. bozemanii serogroup 1, L. micdadei and L. dumoffi. None of the patients with non-legionella pneumonia, however, had significant changes in legionella antibody titres. All of the patients with Gram-negative sepsis had titres of less than 16.

Legionnaires disease: historical perspective

In the summer of 1976, a mysterious epidemic of fatal respiratory disease in Philadelphia launched an intensive investigation that resulted in the definition of a new family of pathogenic bacteria, the Legionellaceae. In retrospect, members of the family had been isolated from clinical specimens as early as 1943. Unsolved epidemics of acute respiratory disease dating to the 1950s were subsequently attributed to the newly described pathogens. In the intervening years, the Legionellaceae have been firmly established as important causes of sporadic and epidemic respiratory disease. The sources of the infecting bacteria are environmental, and geographic variation in the frequency of infection has been documented. Airborne dissemination of bacteria from cooling towers and evaporative condensers has been responsible for some epidemics, but potable water systems are perhaps more important sources. The mode of transmission from drinking water is unclear. The Legionellaceae are gram-negative, facultative, intracellular pathogens. The resident alveolar macrophage, usually an effective antibacterial defense, is the primary site of growth. Cell-mediated immunity appears to be the most important immunological defense; the role of humoral immunity is less clear. Erythromycin remains the antibiotic of choice for therapy of infected patients, but identification and eradication of environmental sources are also essential for the control of infection.

Legionella and Legionnaires' disease: a review with emphasis on environmental studies and laboratory diagnosis

Legionella pneumophila and related species are important causes of epidemic bacterial pneumonia and nosocomial infection. This review will discuss this new family of bacteria and the diseases they produce. The classification, general microbiologic characteristics, and ecology of the bacteria will be reviewed and the epidemiology and clinical aspects of the infection will be discussed. More emphasis will be given to issues that are more directly related to laboratory workers and with which the author has had more direct experience: pathology, laboratory diagnosis of human infection, pathogenesis of the infection, and virulence mechanisms of the bacterium. Therapy and prevention of the infection will be discussed more briefly.

Sporadic Legionnaires' disease: clinical observations on 87 nosocomial and community-acquired cases

To add information about sporadic Legionnaires' disease, 87 cases of L. pneumophila pneumonia were reviewed. Twenty cases were nosocomial infections and 67 cases were community-acquired. Most cases (64%) occurred between July and October. The mean age of patients was 51.4 years and males outnumbered females 2.5:1.0. Thirty-one percent of patients were receiving corticosteroid, immunosuppressive, or antineoplastic chemotherapy when illness began. Immunosuppression at onset of illness was more common in nosocomial infections (90%) than in community-acquired infections (14%). Seventy percent of patients had underlying diseases. Malignancies, renal failure, and transplantation were the most common conditions underlying nosocomial infections. Chronic lung disease and malignancies were the most common diseases underlying community-acquired infections. The case-fatality rate in nosocomial infection (70%) was greater than that in community-acquired disease (22%). Clinical, laboratory, and radiologic features of the cases were examined. Illness ranged from mild to severe. Extrapulmonary findings of encephalopathy and renal failure were more common in fatal than in non-fatal cases. Indirect immunofluorescent and microagglutination antibody responses plateaued by the fourth week of illness. Twenty-nine patients died. The case-fatality rate of patients receiving erythromycin (6%) was less than that of patients receiving penicillin (36%), ampicillin (28%), cephalosporin (32%), or aminoglycosides (41%). Despite erythromycin therapy, the case fatality rate for nosocomial L. pneumophilia pneumonia was unacceptably high (25%).

Symposium on infectious complications of neoplastic disease (Part II). Legionnaires' disease. Aspects of nosocomial infection

Tremendous progress has been made recently in characterization of Legionella pneumophila and infections caused by it. Certain areas that are particularly germane to immunosuppressed patients, who are affected more frequently than other patients, and areas that are controversial and merit particular consideration are considered herein. These include pathogenesis and correlation of experimental and clinical evidence, nosocomial outbreaks and almost ubiquitous distribution of L. pneumophila in water despite only a limited number of studies linking the two by aerosols, prevalence and possible reasons for the apparent spotty distribution, protean clinical manifestations, difficulties in diagnosis, certain aspects of therapy, and control by environmental changes.

Nosocomial Legionnaires' disease. Occurrence in recipients of bone marrow transplants

Nosocomial pneumonia caused by Legionella pneumophila serogroup 1 occurred in five patients after bone marrow transplantation for hematologic malignancies. Two patients died as a result of the infection despite treatment with erythromycin. Serologic screening revealed no other cases of Legionnaires' disease in 40 consecutive recipients of bone marrow transplants, giving a frequency of infection of 13 percent. These five cases represent 23 percent of the pneumonia occurring in this group of patients. Patients undergoing bone marrow transplantation are highly susceptible to infectious complications. Legionnaires' disease must now be added to the list of pathogens infecting this group of patients. Erythromycin is not generally a part of standard empiric antibiotic regimens in febrile neutropenic patients, but appears to be a reasonable addition when pneumonia does not respond to conventional, empiric treatment. Even with appropriate therapy, Legionnaires' disease remains a highly lethal infection in immunocompromised hosts.

Legionnaires' disease in renal transplant patients

Legionnaires disease, which is commonly manifested as pneumonia, was only recently recognized to be a bacterial infection. Diagnosis can be difficult because Gram's stain does not readily stain the bacterium in pulmonary secretions, the organism is not readily cultured, and legionellae is not affected by many commonly used antibiotics. In a retrospective review of all of our transplant patients, we identified 14 cases of Legionnaires' disease after 101 renal transplants. The patients characteristically had high fever, polymorphonuclear leukocytosis, dyspnea and an unproductive cough accompanied by radiographic changes of consolidating pneumonia. Legionnaires' disease can be diagnosed by direct immunofluorescent antibody staining, culture on special media or increases in serum titers of legionella antibodies in surviving patients. Since the recognition of Legionnaires' disease in 1977, we have successfully treated seven renal transplant patients using erythromycin with or without rifampin.

Legionnaires' disease among pneumonias in Iowa (FY 1972-1978) II. Epidemiologic and clinical features of 30 sporadic cases of L. pneumophila infection

We reviewed retrospectively the clinical records of 30 cases of sporadic Legionella pneumophila infection that occurred in Iowa between FY 1972 and 1978. Cases occurred throughout the year, most between May and December. Twenty-one male patients and 9 female patients ranging in age from 5-80 years were infected. Half the patients smoked or had an underlying illness; five were receiving corticosteroids or immunosuppressive therapy. Occupations and exposures related to hospitals, construction and travel were common; four patients had been exposed to birds. In addition to L. pneumophila infection, six patients had evidence of infection with a viral, mycoplasmal, bacterial, mycobacterial or fungal pathogen; three had had preceding dental infections. Twenty-seven cases were pneumonias visible on radiographs. Fever, cough, chills, myalgia and rales occurred inover half the cases. Headache, gastrointestinal symptoms and encephalopathy also were seen. Upper respiratory symptoms were uncommon. Urinalysis and blood studies often suggested renal and hepatic involvement, but other routine laboratory diagnostic tests were not helpful. All but two patients were hospitalized; seven required intensive care. The median duration of hospitalization was 12 days. Two patients who did not receive erythromycin or tetracycline therapy died.

Background prevalence of microagglutination antibodies to Legionella pneumophila serogroups 1, 2, 3, and 4

The background prevalence of microagglutination antibodies to Legionella pneumophila was determined by testing the sera of 517 individuals who lived or worked in a small Iowa town. In this population, the upper limit of normal microagglutination titer for serogroups 1, 3, and 4 was 1:16, and that for serogroup 2 was 1:8. The prevalence of microagglutination titers of greater than or equal to 1:32 against any serogroup of L. pneumophila was only 7.4% and did not vary significantly with age or sex.

Legionnaires' disease bacterium (Legionella pneumophila) multiples intracellularly in human monocytes

We have studied the interaction between virulent egg yolk-grown Legionella pneumophila Philadelphia 1 and human blood monocytes in vitro. The leukocytes were cultured in antibiotic-free tissue culture medium supplemented with 15% autologous human serum.L. pneumophila multiplied several logs, as measured by colony-forming units, when incubated with monocytes or mononuclear cells; the mid-log phase doubling time was 2 h. The level to which L. pneumophila multiplied was proportional to the number of mononuclear cells in the culture. L. pneumophila multiplied only in the adherent fraction of the mononuclear cell population indicating that monocytes but not lymphocytes support growth of the bacteria. Peak growth of L. pneumophila was correlated with destruction of the monocyte monolayer. By fluorescence microscopy using fluorescein conjugated rabbit anti-L. pneumophila antiserum, the number of monocytes containing L. pneumophila increased in parallel with bacterial growth in the culture. At the peak of infection, monocytes were packed full with organisms. By electron microscopy, L. pneumophila in such monocytes were found in membrane-bound cytoplasmic vacuoles studded with structures resembling host cell ribosomes. Several lines of evidence indicate that L. pneumophila grows within monocytes. (a) In the absence of leukocytes, L. pneumophila did not grow in tissue culture medium with or without serum even if the medium was conditioned by monocytes. (b) L. pneumophila did not grow in sonicated mononuclear cells. Lysis of these cells at various times during logarithmic growth of L. pneumophila was followed by cessation of bacterial multiplication. Growth resumed when intact mononuclear cells were added back to the culture. (3) In parabiotic chambers separated by 0.1-mum Nuclepore filters, L. pneumophila multiplied only when placed on the same side of the filter as mononuclear cells. These findings indicate that L. pneumophila falls into a select category of bacterial pathogens that evade host defenses by parasitizing monocytes. It remains to be determined whether cell-mediated immunity plays a dominant role in host defense against L. pneumophila as it does against other intracellular pathogens.

Incidence of Legionnaires' disease in a district general hospital

In order to assess the incidence of Legionnaires' disease in a district general hospital, 90 consecutive patients with pneumonia seen over a 3-year period were investigated. Only 2 patients were found to have Legionnaires' disease, indicating that it is not a frequent cause of pneumonia in the Bristol area.

Indirect immunofluorescence antibodies to Legionella pneumophila: frequency in a rural community

The background prevalence of indirect immunofluorescence antibody to Legionella pneumophila in a rural community was determined by testing sera from 517 volunteers. The upper limit of normal antibody titer was found to be 1:64 with L. pneumophila serogroup 1 (Philadelphia 1) used as antigen. High titers (greater than or equal to 1:128) were found in 13.2% of the sera and occurred with similar frequencies in males and females. In individuals 40 years of age and older, however, high titers were 2.7 times as prevalent in males as females.