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A Legionella-like organism, strain 1677-MI-H, was isolated from the bronchoscopy washings of a patient with pneumonia who had a 2-year history of progressive, chronic lymphocytic leukemia. The growth characteristics, cellular fatty acids, and ubiquinone content of the isolate were consistent with those for Legionella spp. The isolate was serologically distinct in the slide agglutination test with absorbed antisera. DNA hybridization studies showed that strain 1677-MI-H (ATCC 49751) represents a new Legionella species which is named Legionella lansingensis.

Etiology and clinical manifestations have been studied in 153 adult patients with lower respiratory tract infection, and the results are presented according to clinical and radiographic diagnosis. Laboratory investigations revealed that bacterial infection, mycoplasma and chlamydia included, occurred as often in 22 patients whose clinical diagnoses of pneumonia were not evident radiographically, as in 20 patients with radiographic pneumonia. In the latter group significantly higher values of erythrocyte sedimentation rate and C-reactive protein were demonstrated. The most common pathogen was influenzavirus A, followed by respiratory syncytial virus, Streptococcus pneumoniae, and Mycoplasma pneumoniae. Chlamydia pneumoniae infection was found in 3 patients with radiographic pneumonia. The study supports the traditional view that patients with a positive chest radiograph as a rule present more serious manifestations of lower respiratory tract pathology than patients with a normal radiograph. However, as only 1/9 patients with pneumococcal infection and 2/7 with mycoplasmal infection had radiographic evidence of pneumonia, radiography alone did not seem to offer sufficient information for selecting patients for antibacterial therapy.

Three Legionella-like organisms isolated from patients with pneumonia are shown to belong to the species Legionella sainthelensi by DNA hybridization studies and to a new serogroup, serogroup 2, by serological studies (ATCC 49322). L. sainthelensi serogroup 2 and L. santicrucis are indistinguishable by slide agglutination, but are separable on the basis of their cell wall fatty acid profiles.

Legionella anisa, previously found only in environmental specimens, was isolated from a bronchial lavage specimen of an immunocompromised patient with pneumonia. Growth, physiologic, gas-liquid chromatographic, serologic, and DNA characteristics were consistent with those of the type strain of L. anisa, WA-316-C3 (ATCC 35292).

Three strains of Legionella feeleii from patients with pneumonia (425-MI-H, 691-WI-H, and 693-WI-H) and one environmental strain (713-MI-E) received at the Centers for Disease Control for reference diagnostic testing were compared with the type strain WO-44C-C3 (ATCC 35072) by DNA hybridization, chemical analysis of cellular fatty acids and ubiquinones, biochemical tests, and serological characteristics. All four isolates were assigned to the L. feeleii species on the basis of DNA hybridization results. However, strains 691-WI-H and 693-WI-H were serologically distinct from strain WO-44C-C3, as shown by their minimal reactivity (1 to 2+) with a direct immunofluorescence conjugate prepared against L. feeleii serogroup 1 (strain WO-44C-C3). Therefore, strains 691-WI-H and 693-WI-H were placed in a new L. feeleii serogroup (serogroup 2). The reference strain of L. feeleii serogroup 2 is 691-WI-H (ATCC 35849).

A new serogroup of Legionella pneumophila was isolated from bronchoscopic washings and an open-lung biopsy specimen of a patient from California with pneumonia. A serologically identical isolate was obtained from tap water of a hospital ward in the Netherlands, and a fatal case of pneumonia in a patient from Virginia was shown retrospectively to have been caused by this new organism. The type strain of what is now serogroup 9 of L. pneumophila is IN-23-G1-C2 (American Type Culture Collection no. 35289). Disease caused by L. pneumophila serogroup 9 is not apparently different from that caused by other L. pneumophila serogroups.

A Legionella-like organism was isolated from an open-lung biopsy of a patient with fatal pneumonia. The isolate was shown by growth, physiologic, serologic, and genetic characteristics to belong to the species Legionella jordanis, which had previously been isolated only from the environment.

A Legionella-like organism (strain 798-PA-H, ATCC 35999) isolated from a lung aspirate was shown by DNA hybridization to belong to the species Legionella hackeliae. Growth, gas-liquid chromatographic, and physiologic characteristics were consistent with those of the type strain of L. hackeliae, Lansing 2 (ATCC 35250). However, 798-PA-H was minimally reactive with L. hackeliae direct immunofluorescence assay conjugate or slide agglutination test antiserum. Cross-absorption studies with 798-PA-H and Lansing 2 antisera supported placing 798-PA-H in a second serogroup of L. hackeliae.

Legionella maceachernii, previously isolated only from the environment, was shown to be a cause of fatal pneumonia in an immunocompromised patient.

Background. Legionella species, Mycoplasma pneumoniae, and Chlamydia pneumoniae are recognized as important causes of pneumonia in high-income countries, but their significance in middle-income countries, such as Thailand, is unknown. Methods. Population-based surveillance identified inpatient 3489 cases of clinically-defined pneumonia in a rural Thai province for 1 year. Patients who had a chest radiograph performed (for 2059 cases of pneumonia) were enrolled in an etiology study (which included 755 cases of pneumonia among 738 patients). Paired serum, nasopharyngeal swab, and urine specimens were obtained for diagnostic immunologic and molecular tests. Patients aged !18 years were not systematically tested for Legionella species. We report a lower limit of incidence (observed incidence) and an upper limit extrapolated to persons not tested or not enrolled in the study. Results. The incidence of pneumonia due to Legionella longbeachae requiring hospitalization was 5-29 cases per 100,000 population. No case of Legionella pneumophila pneumonia was observed. The definite C. pneumoniae pneumonia incidence was 3-23 cases per 100,000 population; rates were highest among patients aged !1 year (18-166 cases per 100,000 population) and those aged 70 years (23-201 cases per 100,000 population). M. pneumoniae pneumonia had a similar age distribution, with an overall incidence of 6-44 cases per 100,000 population. These pathogens were associated with 15% of all cases of pneumonia. A nonsignificantly higher proportion of patients with pneumonia associated with L. longbeachae, compared with patients with pneumonia associated with M. pneumoniae or C. pneumoniae, required supplemental oxygen or mechanical ventilation (45% vs. 18%; P < .1). Among patients with atypical pneumonia, only 15% received antibiotics with activity against the associated pathogen. Conclusion. M. pneumoniae, C. pneumoniae, and L. longbeachae, but not L. pneumophila, are frequently associated with severe pneumonia in rural Thailand. Few patients receive a tibiotics that cover atypical pathogens. [ABSTRACT FROM AUTHOR]