-
Epidemiology and Infection Nov 2014We investigated a mixed outbreak of Legionnaires' disease (LD) and Pontiac fever (PF) at a military base to identify the outbreak's environmental source as well as known...
We investigated a mixed outbreak of Legionnaires' disease (LD) and Pontiac fever (PF) at a military base to identify the outbreak's environmental source as well as known legionellosis risk factors. Base workers with possible legionellosis were interviewed and, if consenting, underwent testing for legionellosis. A retrospective cohort study collected information on occupants of the buildings closest to the outbreak source. We identified 29 confirmed and probable LD and 38 PF cases. All cases were exposed to airborne pathogens from a cooling tower. Occupants of the building closest to the cooling tower were 6·9 [95% confidence interval (CI) 2·2-22·0] and 5·5 (95% CI 2·1-14·5) times more likely to develop LD and PF, respectively, than occupants of the next closest building. Thorough preventive measures and aggressive responses to outbreaks, including searching for PF cases in mixed legionellosis outbreaks, are essential for legionellosis control.
Topics: Acute Disease; Adult; Age Distribution; Cohort Studies; Confidence Intervals; Disease Outbreaks; Environmental Exposure; Female; Fever; Humans; Incidence; Legionella pneumophila; Legionellosis; Legionnaires' Disease; Male; Middle Aged; Military Facilities; Military Personnel; Respiratory Tract Infections; Retrospective Studies; Risk Factors; Severity of Illness Index; Sex Distribution; United States; Young Adult
PubMed: 25267405
DOI: 10.1017/S0950268813003440 -
Infectious Disease Clinics of North... Mar 2017Nosocomial Legionnaire's disease is most frequently associated with presence of the organism in hospital water systems. Patients are often susceptible as a result of... (Review)
Review
Nosocomial Legionnaire's disease is most frequently associated with presence of the organism in hospital water systems. Patients are often susceptible as a result of age, underlying comorbidities, or immunosuppression. Prevention focuses on reducing the reservoir within water systems and includes super heating, ultraviolent light, chlorination, silver-copper ionization, and distal filtration. This article reviews the epidemiology of health care-associated Legionnaire's disease, reviews characteristics of several health care-associated outbreaks, and discusses strategies to prevent health care-associated infection.
Topics: Cross Infection; Disease Outbreaks; Hospitals; Humans; Legionnaires' Disease; Water Microbiology
PubMed: 27979683
DOI: 10.1016/j.idc.2016.10.011 -
Infectious Disease Clinics of North... Mar 2017Legionnaire's disease (LD) is the pneumonic form of legionellosis caused by aerobic gram-negative bacilli of the genus Legionella. Individuals become infected when they... (Review)
Review
Legionnaire's disease (LD) is the pneumonic form of legionellosis caused by aerobic gram-negative bacilli of the genus Legionella. Individuals become infected when they inhale aerosolized water droplets contaminated with Legionella species. Forty years after the identification of Legionella pneumophila as the cause of the 1976 pneumonia outbreak in a hotel in Philadelphia, we have non-culture-based diagnostic tests, effective antibiotics, and preventive measures to handle LD. With a mortality rate still around 10%, underreporting, and sporadic outbreaks, there is still much work to be done. In this article, the authors review the microbiology, laboratory diagnosis, and epidemiology of LD.
Topics: Adult; Anti-Bacterial Agents; Disease Outbreaks; Female; Humans; Legionella pneumophila; Legionnaires' Disease; Male; Middle Aged; Risk Factors; Water Microbiology
PubMed: 28159177
DOI: 10.1016/j.idc.2016.10.002 -
Current Topics in Microbiology and... 2016The Gram-negative bacterium Legionella pneumophila colonizes extracellular environmental niches and infects free-living protozoa. Upon inhalation into the human lung,... (Review)
Review
The Gram-negative bacterium Legionella pneumophila colonizes extracellular environmental niches and infects free-living protozoa. Upon inhalation into the human lung, the opportunistic pathogen grows in macrophages and causes a fulminant pneumonia termed Legionnaires' disease. L. pneumophila employs a biphasic life cycle, comprising a replicative, non-virulent, and a stationary, virulent form. In the latter phase, the pathogen produces a plethora of so-called effector proteins, which are injected into host cells, where they subvert pivotal processes and promote the formation of a distinct membrane-bound compartment, the Legionella-containing vacuole. In the stationary phase, the bacteria also produce a single monopolar flagellum and become motile. L. pneumophila flagellin is recognized by and triggers the host's NAIP5 (Birc1e)/NLRC4 (Ipaf) inflammasome, which leads to caspase-1 activation, pore formation, and pyroptosis. The production of L. pneumophila flagellin and pathogen-host interactions are controlled by a complex stationary phase regulatory network, detecting nutrient availability as well as the Legionella quorum sensing (Lqs) signaling compound LAI-1 (3-hydroxypentadecane-4-one). Thus, the small molecule LAI-1 coordinates L. pneumophila flagellin production and motility, inflammasome activation, and virulence.
Topics: Animals; Flagella; Host-Pathogen Interactions; Humans; Inflammasomes; Legionella pneumophila; Legionnaires' Disease
PubMed: 27460809
DOI: 10.1007/978-3-319-41171-2_8 -
International Journal of Medical... Jan 2018Legionella pneumophila is an intracellular pathogen and the main causative agent of Legionnaires' disease, a potentially fatal pneumonia. The bacteria infect both... (Review)
Review
Legionella pneumophila is an intracellular pathogen and the main causative agent of Legionnaires' disease, a potentially fatal pneumonia. The bacteria infect both mammalian cells and environmental hosts, such as amoeba. Inside host cells, the bacteria withstand the multifaceted defenses of the phagocyte and replicate within a unique membrane-bound compartment, the Legionella-containing vacuole (LCV). For establishment and maintenance of the infection, L. pneumophila secretes many proteins including effector proteins by means of different secretion systems and outer membrane vesicles. Among these are a large variety of lipolytic enzymes which possess phospholipase/lysophospholipase and/or glycerophospholipid:cholesterol acyltransferase activities. Secreted lipolytic activities may contribute to bacterial virulence, for example via modification of eukaryotic membranes, such as the LCV. In this review, we describe the secretion systems of L. pneumophila, introduce the classification of phospholipases, and summarize the state of the art on secreted L. pneumophila phospholipases. We especially highlight those enzymes secreted via the type II secretion system Lsp, via the type IVB secretion system Dot/Icm, via outer membrane vesicles, and such where the mode of secretion has not yet been defined. We also give an overview on the complexity of their activities, activation mechanisms, localization, growth-phase dependent abundance, and their role in infection.
Topics: Animals; Bacterial Proteins; Humans; Legionella pneumophila; Legionnaires' Disease; Lung; Phospholipases; Type II Secretion Systems; Type IV Secretion Systems; Vacuoles
PubMed: 29108710
DOI: 10.1016/j.ijmm.2017.10.002 -
Frontiers in Cellular and Infection... 2018() is an opportunistic waterborne pathogen and the causative agent for Legionnaires' disease, which is transmitted to humans via inhalation of contaminated water... (Review)
Review
() is an opportunistic waterborne pathogen and the causative agent for Legionnaires' disease, which is transmitted to humans via inhalation of contaminated water droplets. The bacterium is able to colonize a variety of man-made water systems such as cooling towers, spas, and dental lines and is widely distributed in multiple niches, including several species of protozoa In addition to survival in planktonic phase, is able to survive and persist within multi-species biofilms that cover surfaces within water systems. Biofilm formation by is advantageous for the pathogen as it leads to persistence, spread, resistance to treatments and an increase in virulence of this bacterium. Furthermore, Legionellosis outbreaks have been associated with the presence of in biofilms, even after the extensive chemical and physical treatments. In the microbial consortium-containing among other organisms, several factors either positively or negatively regulate the presence and persistence of in this bacterial community. Biofilm-forming is of a major importance to public health and have impact on the medical and industrial sectors. Indeed, prevention and removal protocols of as well as diagnosis and hospitalization of patients infected with this bacteria cost governments billions of dollars. Therefore, understanding the biological and environmental factors that contribute to persistence and physiological adaptation in biofilms can be detrimental to eradicate and prevent the transmission of . In this review, we focus on various factors that contribute to persistence of within the biofilm consortium, the advantages that the bacteria gain from surviving in biofilms, genes and gene regulation during biofilm formation and finally challenges related to biofilm resistance to biocides and treatments.
Topics: Biodiversity; Biofilms; Environment; Environmental Microbiology; Factor Analysis, Statistical; Gene Expression Profiling; Iron; Legionella pneumophila; Legionnaires' Disease; Microbial Viability; Quorum Sensing
PubMed: 29535972
DOI: 10.3389/fcimb.2018.00038 -
Internal Medicine (Tokyo, Japan) Jan 2021Legionellosis is a serious bacterial infection characterized by atypical pneumonia primarily due to infection with Legionella pneumophila, and bathing can be a potential...
Legionellosis is a serious bacterial infection characterized by atypical pneumonia primarily due to infection with Legionella pneumophila, and bathing can be a potential cause of this infection. Legionellosis was first identified in 1977, and it is caused by Gram-negative bacteria belonging to the genus Legionella. Legionellosis remains an important public health threat, particularly in Japan, where the population is rapidly aging, thereby becoming more at risk of developing severe disease and accompanying life-threatening pneumonia. The bacteria are most commonly transmitted via the inhalation of contaminated aerosols produced and broadcast via water sprays, jets or mists. Infection can also occur via the aspiration of contaminated water or ice, or through inhalation of contaminated dust. Because the signs and symptoms of Legionnaires' disease (LD), as well as radiographic imaging are similar to pneumonia caused by other pathogens, a specific diagnostic test is required, such as a urine antigen detection test. Six clinical and laboratory parameters, a high body temperature, a non-productive cough, low serum sodium and platelet counts, and high lactate dehydrogenase (LDH) and c-reactive protein concentrations can be used to reliably predict the likelihood of LD. The first choices for chemotherapy are fluoroquinolone and macrolide antibiotic drugs. The main goals of LD prevention measures are 1) the prevention of microbial growth and biofilm formation, 2) the removal of all biofilm formed on equipment and in facilities, 3) minimizing aerosol splash and spread, and 4) minimizing bacterial contamination from external sources. It is apparent that, in Japan, where hot spring (onsen) bathing is common among aged people, strict regulations need to be in place - and enforced - to ensure that all Japanese onsens and spas provide a safe environment and undertake regular, effective infection control practices.
Topics: Aged; Humans; Japan; Legionella; Legionella pneumophila; Legionellosis; Legionnaires' Disease; Water Microbiology
PubMed: 32727982
DOI: 10.2169/internalmedicine.4852-20 -
Infectious Disease Clinics of North... Mar 2017Imaging examinations are often performed in patients with Legionnaires' disease. The literature to date has documented that the imaging findings in this disorder are... (Review)
Review
Imaging examinations are often performed in patients with Legionnaires' disease. The literature to date has documented that the imaging findings in this disorder are relatively nonspecific, and it is therefore difficult to prospectively differentiate legionella pneumonia from other forms of pneumonia, and from other noninfectious thoracic processes. Through a review of clinical cases and the literature, our objective is for the reader to gain a better understanding of the spectrum of radiographic manifestations of Legionnaires' disease.
Topics: Adult; Aged; Aged, 80 and over; Diagnosis, Differential; Female; Humans; Legionnaires' Disease; Male; Middle Aged; Radiography, Thoracic; Tomography, X-Ray Computed
PubMed: 28159175
DOI: 10.1016/j.idc.2016.10.004 -
Journal of Medical Microbiology Apr 2017Rapid and effective diagnosis of Legionnaires' disease (LD) cases is extremely important so that timely and appropriate therapy can be provided, thereby lowering the... (Review)
Review
PURPOSE
Rapid and effective diagnosis of Legionnaires' disease (LD) cases is extremely important so that timely and appropriate therapy can be provided, thereby lowering the morbidity and mortality rates and reducing the health and economic costs associated with this disease.
METHODOLOGY
Diagnosis is established solely by microbiological tests. There are several methods available, each with different performance, sensitivity and specificity characteristics, and further understanding is required. Our objective was to assess the accuracy of urinary antigen detection, direct fluorescent antibody (DFA) staining, serological testing and the polymerase chain reaction (PCR) method versus culture analysis (the reference standard) in patients suspected of being infected with Legionella or patients with laboratory-confirmed LD. We performed a MEDLINE search in November 2014. Two authors independently assessed the trials and extracted data. Pooled analysis was performed through Meta-DiSc version 1.4.
RESULT
The inclusion criteria were met by 11 studies. All the studies evaluated PCR and DFA tests to detect Legionella in clinical specimens, comparing them to culture techniques, and were included in the meta-analysis. The pooled sensitivity and specificity for PCR were 83 % [95 % confidence interval (CI): 79-87 %] and 90 % (95 % CI: 88-92 %), respectively. DFA was evaluated in one study and the sensitivity and specificity of this test were 67 % (95 % CI: 30-93 %) and 100 % (95 % CI: 91-100 %), respectively. PCR had high sensitivity and specificity for early diagnosis of LD.
CONCLUSION
Culture analysis is deemed necessary for epidemiological studies, molecular strain typing and antibiotic sensibility evaluations; however, the performance of PCR in recent studies calls for additional, well-designed studies in order to achieve the best standard test, which will enable optimization of the Legionella infection diagnostic.
Topics: Antigens, Bacterial; Diagnostic Tests, Routine; Fluorescent Antibody Technique, Direct; Humans; Legionnaires' Disease; Polymerase Chain Reaction; Sensitivity and Specificity
PubMed: 28463665
DOI: 10.1099/jmm.0.000454 -
Journal of Occupational and... Feb 2017Legionellae are waterborne bacteria which are capable of causing potentially fatal Legionnaires' disease (LD), as well as Pontiac Fever. Public concern about Legionella... (Review)
Review
Legionellae are waterborne bacteria which are capable of causing potentially fatal Legionnaires' disease (LD), as well as Pontiac Fever. Public concern about Legionella exploded following the 1976 outbreak at the American Legion conference in Philadelphia, where 221 attendees contracted pneumonia and 34 died. Since that time, a variety of different control methods and strategies have been developed and implemented in an effort to eradicate Legionella from building water systems. Despite these efforts, the incidence of LD has been steadily increasing in the U.S. for more than a decade. Public health and occupational hygiene professionals have maintained an active debate regarding best practices for management and control of Legionella. Professional opinion remains divided with respect to the relative merits of performing routine sampling for Legionella, vs. the passive, reactive approach that has been largely embraced by public health officials and facility owners. Given the potential risks and ramifications associated with waiting to assess systems for Legionella until after disease has been identified and confirmed, a proactive approach of periodic testing for Legionella, along with proper water treatment, is the best approach to avoiding large-scale disease outbreaks.
Topics: Air Conditioning; Disease Outbreaks; Drinking Water; Legionella; Legionnaires' Disease; United States; Water Microbiology; Water Purification
PubMed: 27624495
DOI: 10.1080/15459624.2016.1229481