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- Bernander, Sverker
(författare)
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Detection and epidemiologic subtyping of Legionella pneumophilia using DNA-based molecular methods
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Legionella pneumophila causes 2 - 6 % of hospitalised pneumonia cases. Several community- and hospital-acquired outbreaks have been reported over the years. Legionnaires' disease (LD) or legionellosis is also a frequent cause of pneumonia amongst travellers. Conventional methods for diagnosing legionella infection include culture, detection of antibodies (serology) and urinary antigen. These methods, however, either lack full sensitivity or specificity. Legionellae are found in water distribution systems, especially hot water, and are able to multiply intracellularly in free living protozoa. Thus, the bacteria are transmitted to humans either by aerosols or by microaspiration. It is therefore important to link the patient isolate to possible environmental sources. In this thesis a nested format for polymerase chain reaction (PCR) was constructed for detecting L. pneumophila in clinical specimens. The method, which was highly sensitive and specific, was found to be more rapid than earlier PCR methods. In a multi-centre study, conducted in collaboration with the European Working Group on Legionella Infections (EWGLI), 14 different DNA-based methods were evaluated for typing 114 related and unrelated isolates of L. pneumophila serogroup (sg) 1. The group favoured amplified fragment length polymorphism analysis (AFLP) because of superior reproducibility and epidemiological concordance. In a second phase of the study the use of AFLP was assessed using a standard protocol. In a third phase, 31 AFLP genotypes were designated from a European culture collection of 130 isolates and a proficiency panel was distributed among the participating laboratories. An international database of defined L. pneumophila genotypes was established for the first time. AFLP and to some extent macro-restriction followed by pulsed-field gel electrophoresis (PFGE) was used for the investigation of the molecular epidemiology in four Swedish nosocomial clusters. The genotypes of the causative L. pneumophila strains were different, but the three sg 1 genotypes were found to be widely distributed geographically in Sweden. In these studies, monoclonal antibody (MAb) 3/1positive and negative phenotypes were found inside the same genotypic clusters. For the first time this was proven to be due to a genetic event, which was not reflected in the fingerprinting patterns. The (MAb) 3/1-negative strains thus lacked the lipopolysaccharide associated gene (lag1). Also, for the first time a legionella outbreak was shown to be caused by strains belonging to two different serogroups, sg 4 and 10, that possessed a common fingerprinting pattern. MAb subtyping and genotyping methods should be used together and in conjunction with clinical and epidemiological data in investigations of Legionnaires' disease.
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- Fendukly, Faiz, et al.
(författare)
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Nosocomial Legionnaires´ disease caused by Legionella pneumophila serogroup 6 : Implication of the sequence-based typing method (SBT)
- 2007
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Ingår i: Scandinavian Journal of Infectious Diseases. - : Informa UK Limited. - 0036-5548 .- 1651-1980. ; 39:3, s. 213-216
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Tidskriftsartikel (refereegranskat)abstract
- Sequence-based typing (SBT) was used to determine the allelic profiles of 3 sporadic clinical isolates as well as 7 environmental isolates of Legionella pneumophila serogroup 6, isolated at the Karolinska Hospital during 2004. The clinical isolates were cultured from patients with nosocomial Legionnaires' disease (LD), while the environmental isolates were cultured from potable water sources of the hospital wards in the close vicinity of the 3 patients being investigated. The genes sequenced for the construction of the SBT profile included flaA, pilE, asd, mip, mompS and proA, in this pre-determined order and the allelic profile of the 10 isolates was identical (3, 13, 1, 28, 14, 9). Furthermore, 2 of the isolates, 1 clinical and 1 environmental, were analysed using the amplified fragment length polymorphism analysis (AFLP). The AFLP genotype of both isolates was congruent. Eight of 9 control L. pneumophila serogroup 6 isolates had the same SBT profile as the study isolates. We conclude that the environmental strain isolated from our hospital's drinking water is indistinguishable genotypically from the 3 clinical isolates of Legionella. However, this genotype of L. pneumophila is geographically widespread. Thus, results of genotyping must be evaluated in conjunction with the clinical and epidemiological data.
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- Fraenkel, Carl-Johan, et al.
(författare)
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In vitro activities of three carbapenems against recent bacterial isolates from severely ill patients at Swedish hospitals
- 2006
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Ingår i: Scandinavian Journal of Infectious Diseases. - : Informa UK Limited. - 0036-5548 .- 1651-1980. ; 38:10, s. 853-859
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Tidskriftsartikel (refereegranskat)abstract
- To study the in vitro activity of imipenem, meropenem and ertapenem against common pathogens isolated from patients in intensive care, haematology and dialysis/nephrology units at 7 Swedish university hospitals, a total of 788 isolates were collected during 2002-2003. The distribution of the isolates was as follows: Escherichia coli (n = 140), Klebsiella spp. (n = 132), Proteus spp. (n = 97), Enterobacter spp. (n = 113), Pseudomonas aeruginosa (n = 126), Acinetobacter spp. (n = 53) and Enterococcus faecalis (n = 127). The susceptibility to the 3 carbapenems was determined by E-test, and the MICs were interpreted according to SRGA criteria. All 3 carbapenems were highly active against Enterobacteriaceae. The overall susceptibility to imipenem, meropenem and ertapenem was 90%, 98% and 93%, respectively. Against Enterobacteriaceae, Enterobacter spp. excluded, ertapenem had an equal or lower MIC(90) than meropenem. Apart from being the most active carbapenem against Enterobacteriaceae, meropenem was also the most active carbapenem against P. aeruginosa, whereas imipenem was the most active drug against Acinetobacter spp. The carbapenems are still potent antibiotics. With the introduction of ertapenem, and an expected increase in the carbapenem consumption due to an increased prevalence of strains with extended-spectrum beta-lactamases, continuous surveillance of carbapenem resistance appears to be warranted, with special attention to P. aeruginosa, Enterobacter and Proteus spp.
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- Hugosson, Anna, et al.
(författare)
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A community outbreak of Legionnaires' disease from an industrial cooling tower: assessment of clinical features and diagnostic procedures.
- 2007
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Ingår i: Scandinavian journal of infectious diseases. - : Informa UK Limited. - 0036-5548 .- 1651-1980. ; 39:3, s. 217-24
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Tidskriftsartikel (refereegranskat)abstract
- An outbreak of Legionnaires' disease (LD) occurred in Lidköping, Sweden, in August 2004. A cooling tower was identified as the probable source of infection. During the outbreak period an unexpected 3-6-fold increase in pneumonia patients was noted at the local hospital. During 7 weeks LD was diagnosed in 15 patients by urinary antigen and/or sputum culture. Additionally, 15 LD patients were diagnosed later by serology. Patients with LD were generally younger, more healthy, and more often smokers compared to other pneumonia patients. On admittance they had more severe symptoms with high fever and raised CRP levels, and more often hyponatraemia, gastrointestinal and CNS symptoms. A causative agent besides Legionella was found in 2 patients only. A significant titre rise for Mycoplasma and/or Chlamydophila pneumoniae was found in 13 of 29 tested patients with confirmed LD. We conclude that the clinical diagnosis of LD is difficult and that available diagnostic methods detect only a minority of patients in the acute phase. Therefore in severe pneumonia, empirically targeted therapy should be instituted on clinical grounds irrespective of the results of diagnostic tests. The observation of increased antibody levels for M. and C. pneumoniae suggests an unspecific immune reaction and merits further study.
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- Johansson, Hugo, et al.
(författare)
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Nosocomial transmission of legionella pneumophila to a child from a hospital´s cold-water supply
- 2006
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Ingår i: Scandinavian Journal of Infectious Diseases. - : Informa UK Limited. - 0036-5548 .- 1651-1980. ; 38:11-12, s. 1023-1027
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Tidskriftsartikel (refereegranskat)abstract
- Human Legionella infections mainly consist of community-acquired and nosocomial pneumonia and rarely affect children. We describe a nosocomial infection with Legionella pneumophila, serogroup 1, subgroup OLDA, in an immunocompromized 2-y-old girl at a paediatric clinic. L. pneumophila identical to that of the patient was found in the hospital's cold-water but not in the hot-water distribution system. Transmission of Legionella to the girl most probably occurred by Legionella-contaminated cold water mixed and heated by water from the hot-water system. Mixing of hot and cold water probably occurred through thermostatic water mixing valves connected to showers regulated by a handle at the shower head. Nosocomial Legionella infection might thus have occurred, although circulating hot water temperatures never dropped below 53°C and cultures for surveillance of Legionella from central parts of the hot-water system have been consistently negative. Legionellae were successfully eliminated from the hospital's cold-water distribution system by hot water flushing at 73°C for 1h.
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- Ulleryd, Peter, 1958, et al.
(författare)
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Legionnaires' disease from a cooling tower in a community outbreak in Lidkoping, Sweden-epidemiological, environmental and microbiological investigation supported by meteorological modelling
- 2012
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Ingår i: BMC Infectious Diseases. - : Springer Science and Business Media LLC. - 1471-2334. ; 12, s. 313-
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Tidskriftsartikel (refereegranskat)abstract
- Background: An outbreak of Legionnaires' Disease took place in the Swedish town Lidkoping on Lake Vanern in August 2004 and the number of pneumonia cases at the local hospital increased markedly. As soon as the first patients were diagnosed, health care providers were informed and an outbreak investigation was launched. Methods: Classical epidemiological investigation, diagnostic tests, environmental analyses, epidemiological typing and meteorological methods. Results: Thirty-two cases were found. The median age was 62 years (range 36 - 88) and 22 (69%) were males. No common indoor exposure was found. Legionella pneumophila serogroup 1 was found at two industries, each with two cooling towers. In one cooling tower exceptionally high concentrations, 1.2 x 10(9) cfu/L, were found. Smaller amounts were also found in the other tower of the first industry and in one tower of the second plant. Sero-and genotyping of isolated L. pneumophila serogroup 1 from three patients and epidemiologically suspected environmental strains supported the cooling tower with the high concentration as the source. In all, two L. pneumophila strains were isolated from three culture confirmed cases and both these strains were detected in the cooling tower, but one strain in another cooling tower as well. Meteorological modelling demonstrated probable spread from the most suspected cooling tower towards the town centre and the precise location of four cases that were stray visitors to Lidkoping. Conclusions: Classical epidemiological, environmental and microbiological investigation of an LD outbreak can be supported by meteorological modelling methods. The broad competence and cooperation capabilities in the investigation team from different authorities were of paramount importance in stopping this outbreak.
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