A Prospective Multicenter Study of the Etiological Analysis in Adults with Community-Acquired Pneumonia: Legionella, Leptospira, Hantaan virus and Orientia tsutsugamushi / 감염

BACKGROUND: Despite rigorous investigations, the etiology of community-acquired pneumonia remains unknown in about 50% of hospitalized patients. The diagnosis of the etiological agent is becoming more challenging and more critical as number of newer pathogens have been recognized in recent years. In the 3-year period prospective study we investigated adult patients with community-acquired pneumonia for Legionella, Leptospira, Hantaan virus and Orientia tsutsugamushi as potential etiologic agents. METHODS: A prospective multicenter study was performed from May 1997 to April 2000. A total of 431 patients with community-acquired pneumonia under the inclusion criteria were examined for specific microbial diagnosis; sputum culture and PCR, and serologic teats including indirect immunofluorescence antibody (IFA) test for Legionella, and hemagglutination tests for Leptospira, Hantaan virus and O. tsutsugamushi. Etiologic diagnosis was determined on the basis of the review of case record forms and specific laboratory diagnostic criteria. RESULT: During the study period a total of 385 sputum and 283 serum samples were examined. Legionella pneumonia was diagnosed in 2.3% (10/431) of the cases examined: 1.4% cases with PCR-positive (5/ 367) and 2.1% with positive IFA test (6/283). Leptospirosis and scrub typhus were diagnosed in 0.4% (1/ 252) and 2.0% (5/252), respectively. All 5 cases diagnosed as scrub typhus occurred in late fall, and rash or eschar was not found. None of cases was Hantaan virus infection. CONCLUSION: The results suggest that Legionella, Leptospira, and O. tsutsugamushi should be considered in the etiologic diagnosis and in empirical antibiotic therapy of community-acquired pneumonia.

A Surveillance Study of Cooling Tower Water of Large Buildings in Seoul City for Legionella Species with Molecular Analysis / 감염

BACKGROUND: To prevent and control legionellosis outbreaks, it is important to monitor cooling towers for Legionella and establish epidemiological markers. We determined level of contamination with Legionella of cooling tower in Seoul city, analyzed the distribution of Legionella subtypes, and evaluated molecular typing methods for discrimination power and feasibility. METHODS: Water samples from 120 cooling towers in 25 areas(Gu) of Seoul city were collected during June, 1997. Culture and duplex-PCR(polymerase chain reaction) with Southern hybridization probed with Legionella-specific genes were performed with filtered samples. Twenty-two Legionella isolates were analyzed comparatively by pulsed-field gel electrophoresis(PFGE) and arbitrarily primed(AP)-PCR using a M13 reverse primer. RESULTS: Culture and duplex-PCR with Southern hybridization were positive for Legionella in 22(18.3%) and 106(88.3%) of 120 samples, respectively, resulting in 90.8%(109/120) of contamination level. Out of 22 Legionella isolates, 17 were identified as Legionella pneumophila serogroup 1, 4 as L. pneumophila serogroup 6 and 1 as an unknown. Molecular analysis of 17 isolates of L. pneumophila serogroup 1 showed 7 subtypes by PFGE(A0 in 9 isolates; A1, 2; A2, 1; A3, 2; B, 1; C, 1; D, 1) and 5 subtypes by AP-PCR(Ia in 11 isolates; Ib, 2; Ic, 2; II, 1; III, 1). The agreement of results of both methods was 76.5%(13/17) of L. pneumophila serogroup 1 and 81.8%(18/22) of all isolates, respectively. CONCLUSION: Most of cooling towers in Seoul city were already contaminated with Legionella just before summer, requiring decontamination measures and continuous surveillance. L. pneumophila serogroup 1 was the predominant isolate with variable subtypes. The AP-PCR can be used as a rapid and reproducible screening tool in tracking legionellosis outbreak.