Diagnosis Of Legionnaires' Disease Research Articles

Legionnaires Disease in Solid Organ Transplant Recipients: A Decade-Long Nationwide Study in France

Legionnaires disease (LD) is a rare, life-threatening opportunistic bacterial infection that poses a significant risk to patients with impaired cell-mediated immunity such as solid organ transplant recipients. However, the epidemiologic features, clinical presentation, and outcomes of LD in this population are poorly described. What are the clinical manifestations, radiologic presentation, risk factors for severity, treatment, and outcome of LD in solid organ transplant recipients? In this 10-year multicenter retrospective cohort study in France, where LD notification is mandatory, patients were identified by hospital discharge databases. Diagnosis of LD relied on positive culture findings from any respiratory sample, positive urinary antigen test (UAT) results, positive specific serologic findings, or a combination thereof. Severe LD was defined as admission to the ICU. One hundred one patients from 51 transplantation centers were eligible; 64 patients (63.4%) were kidney transplant recipients. Median time between transplantation and LD was 5.6 years (interquartile range, 1.5-12 years). UAT results were positive in 92%of patients (89/97). Among 31 patients with positive culture findings in respiratory samples, Legionella pneumophila serogroup 1 was identified in 90%. Chest CT imaging showed alveolar consolidation in 98%of patients (54 of 57), ground-glass opacity in 63%of patients (36 of 57), macronodules in 21%of patients (12 of 57), and cavitation in 8.8%of patients (5 of 57). Fifty-seven patients (56%) were hospitalized in the ICU. In multivariate analysis, severe LD was associated with negative UAT findings at presentation (P= .047), lymphopenia (P= .014), respiratory symptoms (P= .010), and pleural effusion (P= .039). The 30-day and 12-month mortality rates were 8%(8 of 101) and 20%(19 of 97), respectively. In multivariate analysis, diabetes mellitus was the only factor associated with 12-month mortality (hazard ratio, 3.2; 95%OR, 1.19-8.64; P= .022). LD is a late and severe complication occurring in solid organ transplant recipients that may present as pulmonary nodules on which diabetes impacts its long-term prognosis.

914: SEPSIS IN THE STREAM: SEVERE LEGIONELLA AND HISTOPLASMA PNEUMONIA ACQUIRED FROM SPRING WATER

Introduction: Legionnaires’ disease (LD) and pulmonary histoplasmosis are important causes of community-acquired pneumonia (CAP). Both infections are acquired via inhalation from a myriad of reported contaminated environmental sources. Herein, we present a case of concurrent LD and pulmonary histoplasmosis ultimately linked to contaminated spring water used in a home continuous positive airway pressure (CPAP) device, highlighting the importance of source identification and proper patient education on device maintenance. Description: A 67-year-old male with obstructive sleep apnea (OSA) was admitted to our ICU for acute respiratory distress syndrome (ARDS) requiring endotracheal intubation after one week of dyspnea associated with fevers, vomiting, and diarrhea. Vital signs on arrival were significant for fever of 102.8°F, vasopressor-dependent hypotension, and refractory hypoxemia despite maximal ventilator support. Thoracic CT revealed bilateral multifocal consolidations and urine legionella antigen test was positive, confirming the diagnosis of LD. He was also diagnosed with possible pulmonary histoplasmosis after serum histoplasma antigen resulted positive. Treatment included salvage ARDS supportive measures and broad-spectrum antimicrobials, including levofloxacin and amphotericin B. His ICU course was complicated by a prolonged ventilator wean requiring tracheostomy. Upon further questioning, the patient’s family revealed he used a nearby spring as his primary water source, including in his home CPAP device. He ultimately transitioned to a step-down unit with plans for outpatient pulmonary follow-up on discharge. Discussion: Legionella pneumonia and pulmonary histoplasmosis both represent significant and potentially fatal causes of CAP. Environmental reservoirs remain the primary source of infection and may persist since investigations are often reserved for large outbreaks. Our case highlights a source of both legionella and histoplasmosis not previously reported. It demonstrates the value of taking a thorough history while recognizing non-traditional sources of both infections. It also highlights the importance of emphasizing proper device maintenance. Increased awareness of risk factors for these infections enables earlier diagnosis and treatment and ideally improves outcomes.

Unmasked: The Impact of the COVID-19 Pandemic on Reported Cases of Legionnaires’ Disease

BackgroundAn increasing public health concern has been the rising incidence of Legionnaires’ disease (LD). The rate of reported cases has increased nearly 9 times since 2000. The emergence of SARS-CoV-2 (COVID-19) in December 2019 constituted a major epidemiological event and has the potential to influence reported cases of LD. Both are respiratory diseases sharing similar clinical presentations and risk groups, which may have confounded the diagnosis of LD — The aim of this study was to investigate the impact of the COVID-19 pandemic on reported cases of LD in 2020 compared to the previous three years (2017-2019).MethodsWe conducted a retrospective descriptive study. A two-sample t-test was used to compare nationally reported cases of LD in 2020 (COVID-19 intervention year) to 2017-2019 (pre-intervention). Syphilis was used as a non-respiratory bacterial disease control. We analyzed data from the Centers for Disease Control and Prevention's (CDC) National Notifiable Disease Surveillance System (NNDSS).ResultsAt the conclusion of 2020 there were 4,245 reported cases of LD. Average monthly cases decreased >50% in the post-intervention period compared to the pre-intervention period (353.75 from 730 respectively; p< 0.005). We did not observe significant changes in reported cases of syphilis post-intervention.ConclusionsReported cases of LD decreased in 2020. Infection control precautions intended to reduce COVID-19 likely contributed to this reduction. Other factors may include delayed reporting, underdiagnosis and low building occupancy. Relaxing precautions and increasing building occupancy may portend spikes in cases in the “post-pandemic” period. Our findings demonstrate the need to better understand the consequences of major epidemiological events on other reportable diseases.

Clinical features of Legionnaires’ disease at three Belgian university hospitals, a retrospective study

ABSTRACT Introduction Legionnaires’ disease (LD) is a recognised cause of community-acquired pneumonia. However, Legionella is an overlooked pathogen in hospital-acquired pneumonia. The European Surveillance System 2008–2017 found 23% of the Belgian LD reported cases being healthcare-related, with a higher death-rate than in community-acquired patients. This study aims to describe patients admitted for community-acquired LD or affected by hospital-acquired LD and investigate discriminants associated with lethality. Methods Medical records were retrospectively reviewed at three Belgian University Hospitals, between 1 January 2016 up to 31 January 2019. Hospital-acquired LD was defined as symptom onset at 10 days or more after admission, according to the Centres for Disease Control and prevention. Community-acquired LD was defined as diagnosis at admission or within 10 days after admission. Results Fifty patients were included in the study, among them 26% were diagnosed with hospital-acquired LD. The case-fatality rate was 22%, with eight of the eleven deceased patients (73%) being in the hospital-acquired LD group. Medical history of asthma or chronic obstructive pulmonary disease and higher sequential organ failure assessment (SOFA) score at diagnosis were more frequently observed in the hospital-acquired LD group. Furthermore, significantly lower SOFA score at diagnosis of LD and higher rates of treatment with levofloxacin or moxifloxacin were observed in survivors. Conclusion In the current cohort, LD death-rate was mainly driven by hospital-acquired LD patients. Hospital-acquired LD might especially affect patients with chronic respiratory disease. Respiratory fluoroquinolones treatment and lower SOFA score at diagnosis may be associated with favourable outcomes.

Legionella pneumophila-Epidemiology and Characterization of Clinical Isolates, Slovenia, 2006-2020.

Legionella pneumophila is the causative agent of severe Legionnaires’ disease (LD). Although an increasing number of LD cases have been observed, published data from Slovenia are very limited and data on molecular epidemiology are even scarcer. The present retrospective study (2006–2020) reports the results of the microbiological diagnosis of LD, as well as the epidemiology and characterization of the Legionella clinical isolates. We tested urine samples from 15,540 patients with pneumonia symptoms for L. pneumophila infection by urine antigen test, of which 717 (4.6%) tested positive. Isolation of L. pneumophila was successfully performed from 88 clinical specimens, with 82 (93.2%) being identified as L. pneumophila sg 1 and six (6.8%) as L. pneumophila sg 2–14. Sequence-based typing (SBT) identified 33 different sequence types (STs), the most frequent being ST1 and ST23. Sequence type 1 mainly comprised isolates belonging to the Philadelphia subgroup, and ST23 mostly to Allentown/France. The standard SBT scheme, as well as Dresden phenotyping for L. pneumophila, presented a high diversity among isolates.

Legionella pneumophila — The causative agent of Legionnaires’ disease

Over the years, Legionella pneumophila has increasingly become a public health threat that causes sporadic and epidemic community-acquired and nosocomial-acquired pneumonia. Thus, this review aims to discuss the current knowledge of L. pneumophila, focusing on the global epidemiology, clinical features, diagnosis and treatment of Legionnaires’ disease (LD). Legionella bacteria are Gram-negative rod-shaped bacteria that are ubiquitous in aquatic environments. L. pneumophila was first discovered in 1976 and recognized as the causative agent of LD. L. pneumophila is a facultative intracellular pathogen that infects and replicates within eukaryotic host cells such as macrophages and protozoan. Diagnosis of LD remains a significant challenge as the clinical manifestation of LD is hardly distinguishable from pneumonia caused by other respiratory pathogens. Therefore, early testing and appropriate treatment are keys to alleviating the rising morbidity and mortality caused by LD.

Legionella SBT applied directly to respiratory samples as a rapid molecular epidemiological tool

Legionnaires’ disease (LD) is an atypical pneumonia caused by the inhalation of Legionella. The methods used for the diagnosis of LD are direct culture of respiratory samples and urinary antigen detection. However, the sensitivity of culture is low, and the urinary antigen test is specific only for L. pneumophila sg1. Moreover, as no isolates are obtained, epidemiological studies cannot be performed. The implementation of Nested-sequence-based typing (Nested-SBT) makes it possible to carry out epidemiological studies while also confirming LD, especially in cases caused by non-sg 1. Sixty-two respiratory samples from patients with Legionella clinically confirmed by positive urinary antigen tests were cultured and tested by Nested-SBT, following the European Study Group for Legionella Infections (ESGLI) protocol. Only 2/62 (3.2%) respiratory samples were culture-positive. Amplification and sequencing of Nested-SBT genes were successfully performed in 57/62 samples (91.9%). The seven target genes were characterised in 39/57 (68.4%) respiratory samples, and the complete sequence type (ST) was obtained. The mip gene was the most frequently amplified and sequenced. Nested-SBT is a useful method for epidemiological studies in culture-negative samples, achieving a 28.7-fold improvement over the results of culture studies and reducing the time needed to obtain molecular epidemiological results.

Legionella and legionnaires' disease: An overview

Legionellosis is the generic term used to describe infections caused by different varieties of Legionella spp., including Legionnaires’ disease (LD), a severe and potentially fatal form of pneumonia, and Pontiac fever, a self-limited flu-like illness. Legionellosis is usually acquired through inhalation or aspiration of aerosols containing Legionella spp. These bacteria can cause acute consolidating pneumonia in susceptible patients who are at an advanced age, have underlying debilitating diseases, or are immunodeficient. The main natural reservoir for Legionella is water and this pathogen colonizes many different natural and man-made freshwater environments such as water networks, cooling towers, and water systems in buildings and hospitals. In recent years, various laboratory diagnostic tests for Legionella infections have changed significantly. Although the sequencing method is nowadays considered the fastest and most reliable method for differentiation and detection of different Legionella species, the isolation of these bacteria from clinical specimens is the golden standard for diagnosis of Legionnaires’ disease. Today the urinary antigen test as the most rapid and inexpensive method is routinely used for diagnosis of LD caused by Legionella pneumophila serogroup 1. The macrolides and fluoroquinolones are still the mainstays for the treatment of Legionella infections. For the prevention of spreading the contaminated water aerosols and controlling Legionella infections, an effective water treatment procedure is necessary. This review describs and summarizes the latest available information about all aspects of Legionella and Legionnaires’ disease.

Discrimination between Legionnaires' Disease and Pneumococcal Pneumonia Based on the Clinical and Laboratory Features: A Quantitative Approach Using the Modified Winthrop-University Hospital Weighted Point System.

Objective Legionnaires' disease (LD) is a common form of lobar pneumonia, but the optimum diagnostic modality has long been a subject of debate due to incomplete sensitivity and specificity. A delay in the initiation of specific therapy for LD is associated with increased mortality. The decision to treat a patient for Legionella must be made quickly. The purpose of this study was to evaluate the ability of the modified Winthrop-University Hospital WUH system to identify LD while discriminating against pneumococcal pneumonia at the time of hospitalization for community-acquired pneumonia. Methods Five patients with LD and 13 patients with pneumococcal pneumonia were retrospectively analyzed. Results The WUH system identified 4 of 5 patients with LD (sensitivity, 80%) while excluding legionellosis in 12 of 13 patients with pneumococcal pneumonia (specificity, 92%). The positive and negative likelihood ratios were 10.4 and 0.2. The area under the receiver operating characteristic curve was 0.969. Conclusion The WUH system is useful for obtaining a rapid presumptive clinical diagnosis of LD. Further investigation with a larger number of patients is strongly recommended.

Prospective evaluation of RT-PCR on sputum versus culture, urinary antigens and serology for Legionnaire's disease diagnosis

Legionnaires' disease (LD) is a severe disease associated with community and hospital-acquired pneumonia, frequently under diagnosed. The main aim of our study was to determine the value of PCR for the diagnosis of LD in routine clinical practice. In a prospective study, from March 2007 to April 2010, the value of PCR on non-invasive respiratory specimens (NIRS) was compared to those of the other available tools for LD diagnosis in patients hospitalized for pneumonia. Among 254 consecutive cases of pneumonia included, 24 cases were LD (19 confirmed and 5 probable) representing the first documented microbiological etiology. Molecular diagnosis of LD was performed on NIRS by using 16S rRNA PCR, and secondarily mip PCR, with no discrepant results between the 2 methods: it was found positive in 14 cases and led to identify 2 supplementary probable cases of LD. Based on clinical and at least 2 positive LD tests, PCR yielded a better diagnostic value than antigen urinary test (12 vs 10 cases). These results revealed that molecular diagnosis of LD on NIRS is reliable and may contribute to better identify cases of LD.

Diagnostic Accuracy of PCR Alone and Compared to Urinary Antigen Testing for Detection of Legionella spp.: a Systematic Review.

The diagnosis of Legionnaires' disease (LD) is based on the isolation of Legionella spp., a 4-fold rise in antibodies, a positive urinary antigen (UA), or direct immunofluorescence tests. PCR is not accepted as a diagnostic tool for LD. This systematic review assesses the diagnostic accuracy of PCR in various clinical samples with a direct comparison versus UA. We included prospective or retrospective cohort and case-control studies. Studies were included if they used the Centers for Disease Control and Prevention consensus definition criteria of LD or a similar one, assessed only patients with clinical pneumonia, and reported data for all true-positive, false-positive, true-negative, and false-negative results. Two reviewers abstracted data independently. Risk of bias was assessed using Quadas-2. Summary sensitivity and specificity values were estimated using a bivariate model and reported with a 95% confidence interval (CI). Thirty-eight studies were included. A total of 653 patients had confirmed LD, and 3,593 patients had pneumonia due to other pathogens. The methodological quality of the studies as assessed by the Quadas-2 tool was poor to fair. The summary sensitivity and specificity values for diagnosis of LD in respiratory samples were 97.4% (95% CI, 91.1% to 99.2%) and 98.6% (95% CI, 97.4% to 99.3%), respectively. These results were mainly unchanged by any covariates tested and subgroup analysis. The diagnostic performance of PCR in respiratory samples was much better than that of UA. Compared to UA, PCR in respiratory samples (especially in sputum samples or swabs) revealed a significant advantage in sensitivity and an additional diagnosis of 18% to 30% of LD cases. The diagnostic performance of PCR in respiratory samples was excellent and preferable to that of the UA. Results were independent on the covariate tested. PCR in respiratory samples should be regarded as a valid tool for the diagnosis of LD.

Characterization of the extent of a large outbreak of Legionnaires' disease by serological assays.

BackgroundIn May 2005, a long-distance outbreak of Legionnaires’ disease (LD) caused by Legionella pneumophila serogroup 1 occurred in south-east Norway. The initial outbreak investigation without serology identified 56 laboratory-confirmed LD cases of whom 10 died. However, 116 patients with community-acquired pneumonia might belong to the outbreak based on epidemiological investigations, but acute laboratory tests other than serology were negative or not performed. To assess the true extent of the outbreak, we evaluated two serological assays in order to reclassify the 116 patients with indeterminate case status.MethodsTwo polyvalent antibody tests, a serogroup 1–6 immunofluorescence assay (IFA) and a serogroup 1–7 enzyme-linked immunosorbent assay (ELISA) were used. They were evaluated with cases defined as culture- or urinary antigen positive LD patients (n = 40) and non-cases defined as confirmed non-LD patients (n = 39) and healthy control subjects (n = 62). The 116 patients, who were negative in culture, polymerase chain reaction and/or urinary antigen tests, were analysed by the same serological assays. Antibodies to the outbreak strain were determined by immunoblotting.ResultsIn the evaluation study, the sensitivity and specificity of a ≥4-fold IFA titre change was 38% and 100%, respectively, with corresponding values of 30% and 99% for seroconversion in ELISA. A single high positive IFA titre yielded sensitivity and specificity of 73% and 97%, respectively, with corresponding values of 68% and 96% for a single high immunoglobulin (Ig) G and/or IgM in ELISA.Based on this evaluation, the following serological testing identified 47 more LD cases, and the outbreak thus comprised 103 cases with a case fatality rate of 10%. About the same proportion (70%) of the urinary antigen positive and negative LD cases had antibodies to the serogroup-specific lipopolysaccharide of the outbreak strain. In addition to the 103 LD cases, Legionella infection could not be verified or excluded in 32 patients based on epidemiology and/or lack of microbiological sampling.ConclusionsThe acute-phase tests (culture, polymerase chain reaction, and urinary antigen) identified less than 55% of the 103 patients in this outbreak. Serological testing thus remains an important supplement for diagnosis of LD and for determination of outbreak cases.

The importance of clinical surveillance in detecting legionnaires' disease outbreaks: a large outbreak in a hospital with a Legionella disinfection system-Pennsylvania, 2011-2012.

Healthcare-associated Legionnaires' disease (LD) is a preventable pneumonia with a 30% case fatality rate. The Centers for Disease Control and Prevention guidelines recommend a high index of suspicion for the diagnosis of healthcare-associated LD. We characterized an outbreak and evaluated contributing factors in a hospital using copper-silver ionization for prevention of Legionella growth in water. Through medical records review at a large, urban tertiary care hospital in November 2012, we identified patients diagnosed with LD during 2011-2012. Laboratory-confirmed cases were categorized as definite, probable, and not healthcare associated based on time spent in the hospital during the incubation period. We performed an environmental assessment of the hospital, including collection of samples for Legionella culture. Clinical and environmental isolates were compared by genotyping. Copper and silver ion concentrations were measured in 11 water samples. We identified 5 definite and 17 probable healthcare-associated LD cases; 6 case patients died. Of 25 locations (mostly potable water) where environmental samples were obtained for Legionella-specific culture, all but 2 showed Legionella growth; 11 isolates were identical to 3 clinical isolates by sequence-based typing. Mean copper and silver concentrations were at or above the manufacturer's recommended target for Legionella control. Despite this, all samples where copper and silver concentrations were tested showed Legionella growth. This outbreak was linked to the hospital's potable water system and highlights the importance of maintaining a high index of suspicion for healthcare-associated LD, even in the setting of a long-term disinfection program.

Current and emerging Legionella diagnostics for laboratory and outbreak investigations.

Legionnaires' disease (LD) is an often severe and potentially fatal form of bacterial pneumonia caused by an extensive list of Legionella species. These ubiquitous freshwater and soil inhabitants cause human respiratory disease when amplified in man-made water or cooling systems and their aerosols expose a susceptible population. Treatment of sporadic cases and rapid control of LD outbreaks benefit from swift diagnosis in concert with discriminatory bacterial typing for immediate epidemiological responses. Traditional culture and serology were instrumental in describing disease incidence early in its history; currently, diagnosis of LD relies almost solely on the urinary antigen test, which captures only the dominant species and serogroup, Legionella pneumophila serogroup 1 (Lp1). This has created a diagnostic "blind spot" for LD caused by non-Lp1 strains. This review focuses on historic, current, and emerging technologies that hold promise for increasing LD diagnostic efficiency and detection rates as part of a coherent testing regimen. The importance of cooperation between epidemiologists and laboratorians for a rapid outbreak response is also illustrated in field investigations conducted by the CDC with state and local authorities. Finally, challenges facing health care professionals, building managers, and the public health community in combating LD are highlighted, and potential solutions are discussed.

Immunochromatic kits Xpect Legionella and BinaxNOW Legionella for detection of Legionella pneumophila urinary antigen have low sensitivities for the diagnosis of Legionnaires’ disease

Urinary antigen tests are the most widely used methods for diagnosing Legionnaires' disease (LD). However, all available urinary antigen tests have the disadvantage that they have low or no sensitivity for serogroups (sgs) other than Legionella pneumophila sg 1. Recently, Oxoid introduced the Xpect Legionella test for detection of L. pneumophila sg 1 and sg 6. In this study, we have evaluated the Xpect kit together with the BinaxNOW kit and compared them with the BinaxEIA kit. One hundred and fifteen urine samples from 91 patients with laboratory-confirmed LD were examined. Ninety-three samples were from 69 culture-proven cases of which 27 samples were from 23 non-sg 1 cases. At the patient level, the overall sensitivities for the three Legionella urinary antigen kits were 79 % for the BinaxEIA, 47 % for the BinaxNOW and 32 % for the Xpect kit. None of the urine samples from the 10 L. pneumophila sg 6 cases were positive by the Xpect kit whereas samples from four of the patients were positive by the BinaxEIA. Overall, the sensitivities for both immunochromatic assays were poor and they should not be used as the sole method for the diagnosis of LD.

Travel-associated Legionnaires disease: clinical features of 17 cases and a review of the literature

We retrospectively investigated patients with Legionnaires disease (LD) who had been admitted to the Baskent University Alanya Teaching and Research Hospital, Ankara, Turkey, from January 2002 to September 2009. Twenty definitive cases were followed as LD, 17 (85%) of which were travel associated. The mean age was 61.5 ± 9.5 years (range, 39–77 years). Diabetes mellitus was found in 7 (41.2%) of those patients. Gastrointestinal or neurologic abnormalities were found approximately in two-thirds and relative bradycardia in 9 (52.9%). LD was severe in 11 (64.7%) patients, which required intensive care unit follow-up. Although appropriate antibiotic therapy was initiated in all patients on admission day, 4 (23.5%) deaths occurred. In conclusion, clinicians should remain vigilant about the diagnosis of LD in patients with community-acquired pneumonia, especially in the presence of extrapulmonary involvement, risk factors for LD, and a history of recent travel. As in our cases, mortality is still high in sporadic cases despite early appropriate treatment.

Comparison of the sensitivity of the Legionella urinary antigen EIA kits from Binax and Biotest with urine from patients with infections caused by less common serogroups and subgroups of Legionella

The detection of urinary antigen is the most widely used method to diagnose Legionnaires' disease (LD), so it is important that these assays have a high sensitivity for the disease. In this study, we compare two kits for their ability to detect urinary antigen in urine samples from patients infected with Legionella species and L. pneumophila sero- and subgroups not considered as the most common causes of LD. Urine samples (n = 33) from 30 culture-proven cases of L. pneumophila serogroup (sg) 1, subgroup non-Pontiac infection, and urine samples (n = 35) from 32 cases of non-L. pneumophila species or non-sg 1 infection were examined using the Binax EIA and Biotest EIA kits. For both groups, the overall diagnostic sensitivity of the Binax kit was significantly better than the sensitivity of the Biotest kits (P < 0.0001). For the non-Pontiac group, the sensitivity was 81.8 and 42.4%, respectively, and for the non-sg1 group, it was 51.4 and 28.6%, respectively. It was concluded that the Binax kit was more suitable for the general diagnosis of LD than the Biotest kit, but we still need urinary antigen detection methods with higher sensitivity for non-sg1 LD.

Severe form of Legionnaires' disease in an immunocompetent patient

Legionnaires' disease (LD) is a pneumonia caused by Legionella pneumophila (LP). The disease occurs more often in immunocompromised persons and can be manifested by severe pneumonia, multiple organ failure and has a high mortality. Immunocompetent patient, male, 53-year old, with severe form of LB had fever, cough, weakness and diarrhea as the initial symptoms of the disease. Laboratory results showed increased number of leukocytes, increased values of acute phase proteins, liver enzymes and hyponatremia. Computed tomography of the chest showed the marked inflammatory lessions on both sides. Pathohistological analysis of the samples retrieved by bronchoscopy pointed to a pneumonia, and diagnosis of LD was confirmed by positive urine test for LP antigen. Later, the disease was complicated by acute adult respiratory distress syndrome (ARDS). Treatment with antibiotics (erythromycin, rifampicin, azithromycin) combined with ARDS treatment led to a clinical recovery of the patient together with complete resolution of inflammatory lesions seen on chest radiography. In severe pneumonias it is necessary to consider LD in differential diagnosis, perform tests with aim of detecting LP and apply adequate antibiotic treatment in order to accomplish positive outcome of the therapy and prevent complications.

Investigation of an outbreak of Legionnaires’ disease: Hereford, UK 2003

This report describes the investigation and control of a community outbreak of Legionnaires' disease in Hereford, UK, in November 2003. Outbreak investigation consisted of epidemiological survey, identification and environmental investigation of potential sources, microbiological analysis of clinical and environmental samples and mapping the location of potential sources and the movement and residence of cases. Each identified source was allocated a 'composite score' based on different zones of exposure and wind direction. Altogether, 28 cases were identified, with an overall case fatality rate of 7%. All cases had epidemiological links to Hereford city centre. The 'composite score' identified a cluster of cooling towers as being the most likely source of the outbreak. Environmental samples from one of the cooling towers in the cluster and clinical samples from two patients were positive for Legionella pneumophilia serogroup 1 and were indistinguishable by molecular sub-typing. In this outbreak, the use of microbiological, environmental and epidemiological techniques facilitated the rapid identification of a cooling tower as the source of this outbreak. This study illustrates the continuing importance of cooling towers as a source of Legionnaires' disease and the utility of obtaining and comparing both clinical and environmental samples.

Evaluation of real-time PCR for the early detection of Legionella pneumophila DNA in serum samples

Legionella pneumonia can be difficult to diagnose. Existing laboratory tests all have shortcomings, especially in the ability to diagnose Legionnaires' disease (LD) at an early stage of the disease in a specimen that is readily obtainable. The aim of this study was to assess the performance of PCR as a rapid diagnostic method and to compare the results of different PCR assays of serum samples from patients with LD. Samples included 151 serum samples from 68 patients with proven LD and 60 serum samples from 36 patients with respiratory tract infections other than Legionella. PCR assays were based on the 5S rRNA gene, 16S rRNA gene and the mip gene. The samples from patients with infections caused by pathogens other than Legionella all tested negative in PCR. Among the patients with proven LD 54.4 % (37/68) tested positive in 5S rRNA PCR, 52.9 % (36/68) in mip gene PCR and 30.9 % (21/68) in 16S rRNA PCR in the first available serum sample. The association between threshold cycle value in 5S PCR positive serum samples (n=49) and C-reactive protein value was determined, and showed a strong negative correlation (Pearson correlation coefficient r=-0.63, P<0.0001). In addition to existing tests for the diagnosis of LD, detection of Legionella DNA in serum could be a useful tool for early diagnosis of LD caused by any Legionella species and serogroup, and has the potential to provide a diagnosis in a time frame that could affect initial infection management.