The effect of a large Legionnaires' disease outbreak in Southwest Edinburgh on acute and critical care services

Legionella Pneumonia in the ICU: A Tertiary Care Center Experience Over 10 Years

OBJECTIVES:

Few studies have reported the complications and outcomes of patients with Legionella pneumonia requiring ICU admission. The objective of our study is to report the clinical course, complications, and 30-day mortality of patients with Legionella pneumonia admitted to the critical care units at our medical center over a 10-year period.

DESIGN:

Retrospective observational study.

SETTING:

Tertiary care teaching hospital.

PATIENTS:

All adult (≥ 18 yr old) patients with Legionella pneumonia admitted to the ICUs from January 1, 2010, to December 31, 2019.

INTERVENTIONS:

None.

MEASUREMENTS AND MAIN RESULTS:

A total of 88 patients with Legionella pneumonia were admitted to ICUs over the 10-year period. The majority of infections (n = 80; 90.9%) were community acquired. The median (interquartile range) age of patients was 60 years (51.5–71.0 yr); 58 (66%) were male, and 41 (46.6%) identified their race as Black. The median (interquartile range) Sequential Organ Failure Assessment score at ICU admission was 6 (3–9). The distribution of infections showed seasonal dominance with most cases (86%) occurring in the summer to early fall (May to October). Invasive mechanical ventilation was required in 62 patients (70.5%), septic shock developed in 57 patients (64.8%), and acute respiratory distress syndrome developed in 42 patients (47.7%). A majority of patients developed acute kidney injury (n = 69; 78.4%), with 15 (21.7%) receiving only intermittent hemodialysis and 15 (21.7%) requiring continuous renal replacement therapy. Ten patients required venovenous extracorporeal membrane oxygenation support; eight (80%) survived and were successfully decannulated. Overall 30-day mortality was 26.1% (n = 23). Advanced age, higher Sequential Organ Failure Assessment score at admission, and not receiving Legionella-specific antimicrobial therapy within 24 hours of hospital admission were predictors of 30-day mortality.

CONCLUSIONS:

Patients with Legionella pneumonia may require ICU admission and major organ support. Legionella-targeted antibiotics should be included in the empiric regimen for any patient with severe pneumonia. Outcomes of extracorporeal membrane oxygenation therapy in this population are encouraging.

Dispersion of Legionella bacteria in atmosphere: A practical source location estimation method

Legionnaires’ disease, a form of pneumonia which can be fatal, is transmitted via the inhalation of water droplets containing Legionella bacteria. These droplets can be dispersed in the atmosphere several kilometers from their source. The most common such sources are contaminated water within cooling towers and other air-conditioning systems but other sources such as ornamental fountains and spa pools have also caused outbreaks of the disease in the past. There is an obvious need to locate and eliminate any such sources as quickly as possible. Here a maximum likelihood model estimating the source of an outbreak from case location data has been developed and implemented. Unlike previous models, the average dose exposure sub-model is formulated using a atmospheric dispersion model. How the uncertainty in inferred parameters can be estimated is discussed. The model is applied to the 2012 Edinburgh Legionnaires’ disease outbreak.

Legionnaires' disease in Europe, 2011 to 2015

Under the coordination of the European Centre for Disease Prevention and Control (ECDC), the European Legionnaires’ disease Surveillance Network (ELDSNet) conducts surveillance of Legionnaires’ disease (LD) in Europe. Between 2011 and 2015, 29 countries reported 30,532 LD cases to ECDC (28,188 (92.3%) confirmed and 2,344 (7.7%) probable). Four countries (France, Germany, Italy and Spain) accounted for 70.3% of all reported cases, although their combined populations represented only 49.9% of the study population. The age-standardised rate of all cases increased from 0.97 cases/100,000 population in 2011 to 1.30 cases/100,000 population in 2015, corresponding to an annual average increase of 0.09 cases/100,000 population (95%CI 0.02–0.14; p = 0.02). Demographics and infection setting remained unchanged with ca 70% of cases being community-acquired and 80% occurring in people aged 50 years and older. Clinical outcome was known for 23,164 cases, of whom 2,161 (9.3%) died. The overall case fatality ratio decreased steadily from 10.5% in 2011 to 8.1% in 2015, probably reflecting improved reporting completeness. Five countries (Austria, Czech Republic, Germany, Italy, and Norway) had increasing age-standardised LD notification rates over the 2011−15 period, but there was no increase in notification rates in countries where the 2011 rate was below 0.5/100,000 population.

A Large Community Outbreak of Legionnaires' Disease Associated With a Cooling Tower in New York City, 2015

OBJECTIVES

Infections caused by Legionella are the leading cause of waterborne disease outbreaks in the United States. We investigated a large outbreak of Legionnaires' disease in New York City in summer 2015 to characterize patients, risk factors for mortality, and environmental exposures.

METHODS

We defined cases as patients with pneumonia and laboratory evidence of Legionella infection from July 2 through August 3, 2015, and with a history of residing in or visiting 1 of several South Bronx neighborhoods of New York City. We describe the epidemiologic, environmental, and laboratory investigation that identified the source of the outbreak.

RESULTS

We identified 138 patients with outbreak-related Legionnaires' disease, 16 of whom died. The median age of patients was 55. A total of 107 patients had a chronic health condition, including 43 with diabetes, 40 with alcoholism, and 24 with HIV infection. We tested 55 cooling towers for Legionella, and 2 had a strain indistinguishable by pulsed-field gel electrophoresis from 26 patient isolates. Whole-genome sequencing and epidemiologic evidence implicated 1 cooling tower as the source of the outbreak.

CONCLUSIONS

A large outbreak of Legionnaires' disease caused by a cooling tower occurred in a medically vulnerable community. The outbreak prompted enactment of a new city law on the operation and maintenance of cooling towers. Ongoing surveillance and evaluation of cooling tower process controls will determine if the new law reduces the incidence of Legionnaires' disease in New York City.

Molecular diagnosis of Legionella infections--Clinical utility of front-line screening as part of a pneumonia diagnostic algorithm

OBJECTIVES

Urinary antigen testing for Legionella pneumophila serogroup 1 is the leading rapid diagnostic test for Legionnaires' Disease (LD); however other Legionella species and serogroups can also cause LD. The aim was to determine the utility of front-line L. pneumophila and Legionella species PCR in a severe respiratory infection algorithm.

METHODS

L. pneumophila and Legionella species duplex real-time PCR was carried out on 1944 specimens from hospitalised patients over a 4 year period in Edinburgh, UK.

RESULTS

L. pneumophila was detected by PCR in 49 (2.7%) specimens from 36 patients. During a LD outbreak, combined L. pneumophila respiratory PCR and urinary antigen testing had optimal sensitivity and specificity (92.6% and 98.3% respectively) for the detection of confirmed cases. Legionella species was detected by PCR in 16 (0.9%) specimens from 10 patients. The 5 confirmed and 1 probable cases of Legionella longbeachae LD were both PCR and antibody positive.

CONCLUSIONS

Front-line L. pneumophila and Legionella species PCR is a valuable addition to urinary antigen testing as part of a well-defined algorithm. Cases of LD due to L. longbeachae might be considered laboratory-confirmed when there is a positive Legionella species PCR result and detection of L. longbeachae specific antibody response.

Barrow-in-Furness: a large community legionellosis outbreak in the UK

A community outbreak of legionellosis occurred in Barrow-in-Furness, Cumbria, during July and August 2002. A descriptive study and active case-finding were instigated and all known wet cooling systems and other potential sources were investigated. Genotypic and phenotypic analysis, and amplified fragment length polymorphism of clinical human and environmental isolates confirmed the air-conditioning unit of a council-owned arts and leisure centre to be the source of infection. Subsequent sequence-based typing confirmed this link. One hundred and seventy-nine cases, including seven deaths [case fatality rate (CFR) 3·9%] were attributed to the outbreak. Timely recognition and management of the incident very likely led to the low CFR compared to other outbreaks. The outbreak highlights the responsibility associated with managing an aerosol-producing system, with the potential to expose and infect a large proportion of the local population and the consequent legal ramifications and human cost.