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An Overview of Microbes Pathogenic for Humans
Published in Nancy Khardori, Bench to Bedside, 2018
Eric Lehrer, James Radike, Nancy Khardori
Legionella species are aerobic, gram-negative bacilli; L. pneumophila is the most frequently encountered species. This bacteria is responsible for causing two important clinical syndromes—Legionairre’s Disease, which presents as pneumonia with high fever, and Pontiac Fever, which is an acute febrile illness that is self-limited with negligible respiratory symptoms. Legionella is known to thrive in damp environments and water distribution systems, such as supermarket mists and air conditioners.
Legionella Pneumophila Infection
Published in Meera Chand, John Holton, Case Studies in Infection Control, 2018
In the UK, all cases must be reported to the local Public Health Unit. Pontiac fever is a systemic illness without pneumonia associated with the same bacterium. The urinary antigen is rarely positive and patients generally recover without therapy.
Hazards from Legionella *
Published in Jamie Bartram, Rachel Baum, Peter A. Coclanis, David M. Gute, David Kay, Stéphanie McFadyen, Katherine Pond, William Robertson, Michael J. Rouse, Routledge Handbook of Water and Health, 2015
The primary human disease caused by Legionella is Legionnaires’ disease a severe pneumonia that may have a fatality rate of as much as 25 per cent of those affected. The secondary cause of disease is Pontiac fever, a non-fatal flu-like illness with a short incubation period and short duration. Initial symptoms may present as a cold/flu-like malaise, including coughing, muscle aches, dizziness and nausea. These progress to a ‘full blown’ pneumonia with respiratory distress, spiking fever, disorientation and multi-organ involvement. Legionella infections are not laterally (person to person) transmitted. The introduction of the Legionella bacteria into the lung from contaminated water is an undisputed cause of infection. This may be via inhalation of aerosol or by aspiration of water droplets. Aerosol inhalation appears to be the route of transmission of disease for the majority of reported cases of disease, though the contribution of aspiration through ingestion of contaminated water is clearly significant. Cases of disease are usually individuals who are immune compromised by smoking, existing respiratory disease, age (>50 years unless there are other predisposing factors), high alcohol intake or deliberate immune suppression (transplant recipients). By far the highest risk factor is smoking regardless of other considerations. The incubation period before disease is evident can be anything from 1 to 21 days after exposure, though the median is between 5 and 7 days. This long incubation period makes identifying a source of exposure problematic (Fields et al., 2002; WHO, 2007, Ch. 1).
Whole-genome sequencing of the clinical isolate of Legionella pneumophila ALAW1 from the West Bank allows high-resolution typing and determination of pathogenicity mechanisms
Published in European Clinical Respiratory Journal, 2023
Ashraf R. Zayed, Boyke Bunk, Lina Jaber, Hadeel Abu-Teer, Mousa Ali, Michael Steinert, Manfred G. Höfle, Ingrid Brettar, Dina M. Bitar
L.pneumophila is an opportunistic bacterial pathogen with widespread distribution in freshwater environments. This bacterial species is the main etiology of legionellosis worldwide except Australia and New Zealand [1–3]. The term ‘legionellosis’ describes Legionnaires’ disease (LD), a severe form of atypical pneumonia, and a non-pneumonic febrile illness called Pontiac Fever. L. pneumophila has 15 serogroups (Sgs); Sg1 is the most common causative agent of LD, followed by Sg6 [4,5]. Many studies have demonstrated that an important source for LD is the drinking water distribution systems (DWDS) in large buildings like hospitals and hotels [6–8]. The contamination of hospital water systems with L. pneumophila is considered to pose a high risk for patients, especially for vulnerable and immunocompromised people. To this end, it is well known that LD is an important cause of hospital-acquired pneumonia [9]. The presence of L. pneumophila in DWDS could be a serious health risk to hospital staff and patients, but the magnitude of the problem is often unrecognized [1,9].
Clinical features of Legionnaires’ disease at three Belgian university hospitals, a retrospective study
Published in Acta Clinica Belgica, 2022
Marco moretti, Sabine D. Allard, Nicolas Dauby, Deborah De Geyter, Bhavna Mahadeb, Véronique Y. Miendje, Eric V. Balti, Philippe Clevenbergh
Sixty-two patients with a positive LUA or RT-PCR for LD on respiratory samples were considered. Eight cases were excluded as they did not match the criteria of LD diagnosis. Indeed, they were previously diagnosed with Pontiac fever. Four other patients were not included in the current study as their medical records were incomplete and the date of symptoms’ onset was not mentioned. Fifty LD patients were hence enrolled. The median age was 64 (IQR: 52–74) years and 72% (36) were male. Urinary antigen detection test was requested in all patients and was positive in 94% (47) of cases. Forty-two LD cases (84%) were diagnosed only with LUA. Eight cases (16%) were diagnosed with PCR performed on respiratory specimens. Among them, five patients were affected by Lp1 and three by Legionella pneumophila serogroup 3, this last three patients had a false-negative LUA. All patients except one received a validated antibiotic regimen for Legionella. The patient, who did not receive any effective antibiotics, died at diagnosis. Moxifloxacin was chosen in 21 (42%) cases and high-dose levofloxacin was used in 18 (36%). Other regimens were ciprofloxacin in six patients (12%) and clarithromycin in four patients (8%). The median length of treatment was 12 days (IQR: 10–20).
Detection of amoeba-associated Legionella pneumophila in hospital water networks of Johannesburg
Published in Southern African Journal of Infectious Diseases, 2018
P Muchesa, M Leifels, L Jurzik, TG Barnard, C Bartie
Legionella species are gram-negative, non-spore-forming, rod-shaped or filamentous fastidious aerobic bacteria. They have been isolated from man-made aquatic environments such as cooling towers, hot tubs, air-conditioning systems and potable water systems where they can proliferate at temperatures between 20° and 50°C.1,2. Among the 58 described Legionella spp., Legionella pneumophila serogroup 1 is the most common serotype responsible for at least 84% of infections in humans. Inhalation of aerosols containing Legionella spp. may result in two kinds of infections, the mild, non-fatal, influenza-like illness Pontiac fever and the severe form of pneumonia and potentially fatal Legionnaires’ disease (LD) in both community and health-care settings. Aspiration of contaminated water or direct contact with surgical wounds are the other less common modes of transmission.3 Worldwide, there are few LD cases where the environmental source of Legionella infection is determined successfully. Studies have shown that contaminated potable water supplies within hospitals could be responsible for hospital-acquired LD cases.4,5