ABSTRACT
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.
Subject(s)
Decontamination , Discrimination, Psychological , Disease Outbreaks , Legionella pneumophila , Legionella , Legionellosis , Mass Screening , Molecular Typing , Seoul , WaterABSTRACT
BACKGROUND: Because of the ubiquity of Legionella species in aquatic environments, molecular epidemiological analysis of Legionella isolates is important in investigation for source of infection and subsequent control of nosocomial legionellosis. In association with an unusual cluster of nosocomial pneumonia with Legionella in a tertiary-care hospital, we performed an environmental surveillance with molecular epidemiological study of Legionella isolates. METHODS: We randomly collected 20 samples of environmental and portable water from the hospital where three cases of Legionella pneumonia occurred consecutively during the period of 5 months. We detected Legionella from the samples by using both culture and polymerase chain reaction(PCR), and analyzed Legionella isolates from patients and environmental samples together with 12 reference strains by ribotyping using HpaI and EcoRI. RESULTS: Legionella was isolated from 3 out of 20(15%) samples by culture, and detected in 9 of 20(45%) by PCR. Ribotyping analysis showed that 2 patients' and 2 environmental isolates from a faucet of the patient's room and an air handling unit shared the same pattern which was also identical to that of Legionella pneumophila serogroup 6, a reference strain. CONCLUSION: The study showed that the hospital environments were contaminated with at least 2 Legionella species including L. pneumophila serogroup 6, and indicated that an unusual cluster of Legionella pneumonia occurred in the hospital was possibly linked to the contamination of a faucet with L. pneumophila serogroup 6.
Subject(s)
Humans , Environmental Monitoring , Epidemiologic Studies , Legionella pneumophila , Legionella , Legionellosis , Pneumonia , Polymerase Chain Reaction , Ribotyping , WaterABSTRACT
Nosocomial Legionnaires' disease has often been documented to occur in immunocompromised patients and to be severe, potentially fatal, pneumonia. We report a case of fatal nosocomial Legionnaires' disease developed shortly after steroid pulse therapy. A 39-year old woman with systemic lupus erythematosus was admitted via emergency room due to generalized edema and gross hematuria. Under the diagnosis of lupus nephritis, she was given intravenous steroid pulse therapy for 3 days and then maintained with oral prednisolone. On the 7th day of admission the patient's conditions got worse with progression to acute renal failure and respiratory difficulty. On the 10th day of admission when she was started on hemodialysis, chestradiograph showed newly developed multifocal mass-like consolidations on both lung fields. In spite of empirical therapy with roxithromycin and rifampin, the consolidations were aggravated and rapidly extended to both whole lung fields. On the 15th day of admission she was mechanically ventilated due to respiratory failure, but died of hypoxia and shock on the 19th day. Later, a legionella species was isolated from the tracheal aspirates and identified as L. pneumophila serogroup 1. We also detected L. pneumophila from the tracheal aspirates by duplex PCR which amplified both 5S rRNA and mip genes of L. pneumophila.