Legionnaires\' disease is a severe form of pneumonia caused by Legionella spp. bacteria. According to the European Centre for Disease Prevention and Control, problems related to this pathogen showed a significant surge in recent years, making its monitoring critical.

Legionnaires\' disease (LD) is a serious sometimes fatal pneumonia caused by Legionella pneumophila. The clinical manifestations of LD may be similar to those by caused by Streptococcus pneumoniae. As both conditions can be serious illnesses but requiring different antimicrobial therapies, factors that can help differentiate these types of pneumonias can be helpful in the clinical management of hospitalized patients with bacterial pneumonia. This study aimed to compare clinical features and indicators of disease progression in hospitalized patients with community-acquired pneumonia caused by L. pneumophila and bacteremic S. pneumoniae.
We conducted a retrospective case comparison study of adult patients hospitalized with LD or S. pneumoniae. Data collected included demographic, clinical characteristics, and comorbidities, and outcomes. Data were analyzed using SPS vs 24.0. Multivariable analysis was done using logistic regression with a forward stepwise algorithm.
A total of 106 patients met study criteria. The incidence of LD peaked in summer months and S. pneumoniae peaked in the winter quarter. From multivariable analysis predictors of LD were male gender (OR=21.6, p < 0.001), diarrhea (OR=4.5, p = 0.04), body mass index (BMI) (OR=1.13, p = 0.02), hyponatremia (OR=5.6, p = 0.03 and Charlson weighted index of comorbidity (CWIC) score (OR=0.61, p = 0.01). Patients with S. pneumoniae had higher rates of mechanical ventilation, septic shock, and death than those with LD.
Our data suggests that variables that may distinguish LD from S. pneumoniae include male gender, diarrhea, hyponatremia, higher temperature on admission, higher BMI and fewer comorbidities. Bacteremic S. pneumoniae was associated with poorer outcomes than LD including higher rates of septic shock, mechanical ventilation, ICU admission, and death.

Legionnaire\'s disease is an uncommon pneumonic disease that can carry a mortality rate up to 20%. It commonly presents as an atypical lower respiratory illness. However, it is important to be mindful of the various extra-pulmonic presentations of the infection. Here, we present a case of a 51-year-old female who presented to the emergency department with lethargy, slurred speech, and confusion. Legionella has been reported to present with neurological symptoms but it is not a common occurrence in each hospitalization. These neurological symptoms often lead to an extensive workup and the complexity of the diagnostic workup can significantly influence patient outcome. However, it is crucial that physicians follow a systemic approach to establish a diagnosis in an expedited manner. This case emphasizes the importance of key objective evidence of legionella that can help guide a physician\'s diagnostic approach.

From 2011 through 2018, there was a notable increase in sporadic Legionnaires\' disease in the state of Minnesota. Sporadic cases are those not associated with a documented outbreak. Outbreak-related cases are typically associated with a common identified contaminated water system; sporadic cases typically do not have a common source that has been identified. Because of this, it is hypothesised that weather and environmental factors can be used as predictors of sporadic Legionnaires\' disease. An ecological design was used with case report surveillance data from the state of Minnesota during 2011 through 2018. Over this 8-year period, there were 374 confirmed Legionnaires\' disease cases included in the analysis. Precipitation, temperature and relative humidity (RH) data were collected from weather stations across the state. A Poisson regression analysis examined the risk of Legionnaires\' disease associated with precipitation, temperature, RH, land-use and age. A lagged average 14-day precipitation had the strongest association with Legionnaires\' disease (RR 2.5, CI 2.1-2.9), when accounting for temperature, RH, land-use and age. Temperature, RH and land-use also had statistically significant associations to Legionnaires\' disease, but with smaller risk ratios. This study adds to the body of evidence that weather and environmental factors play an important role in the risk of sporadic Legionnaires\' disease. This is an area that can be used to target additional research and prevention strategies.

Legionella-related disease is caused by an intracellular bacteria mainly living in water. Contamination results from inhalation of Legionella sp containing aerosolized water. Main risk factors are tobacco, immunodeficiency, and advanced age. Antigenuria is the cornerstone of the diagnosis. Immunocompromised patients, more commonly infected with non pneumophilaLegionella, present negative antigenuria, and culture and PCR are essential for the diagnosis. Legionnaires\' disease may be severe, especially in elderly and/or immunocompromised patients. Mortality rate varies from 10 % in the general population to 50 % in intensive care. Treatment is based on macrolides or fluoroquinolones. Antibiotic resistance is very rare.

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L. pneumophila is an unusual cause of pneumonia with a prevalence of 2.7%, and it is even more uncommon in pregnancy. To date, only 11 cases of Legionnaire\'s Disease in pregnancy have been reported, though this small number could possibly be attributed to underdiagnoses and under documentation. Case Presentation: In this paper, we present a 31-year-old Hispanic female, gravida 4, para 1 from the southwest United States who presented with a 3-week history of fever, worsening cough, dyspnea on exertion, and hypoxemia. Chest x-ray showed bibasilar infiltrates, with positive serology for Legionella IgM and IgG (1:250 and 1:640 respectively), as well as positive urinary antigen. Despite appropriate treatment with azithromycin 500 mg, she continued to have dyspnea and mild respiratory distress. Conclusion: Upon follow up, mother and fetus initially remained stable without any signs of sequelae from Legionnaire\'s disease, but the patient miscarried 5 weeks after the second admission to the hospital. The chest x-ray eventually cleared up after almost 21 days of azithromycin.

According to the Centers for Disease Control and Prevention (CDC), from 2000 to 2014, reported cases of legionellosis per 100 000 population increased by 300% in the USA, although reports on disease seasonality are inconsistent. Using two national databases, we assessed seasonal patterns of legionellosis in the USA. We created a monthly time series from 1993 to 2015 of reported cases of legionellosis from the CDC, and from 1997 to 2006 of medical claims of legionellosis-related hospitalisation in older adults from the Centers for Medicaid and Medicare Services (CMS). We split the study time interval into two segments (before and after 2003), and applied a Poisson harmonic regression model to each dataset and each segment. The time series of monthly counts exhibited a significant shift of seasonal peaks from mid-September (9.676 ± 0.164 months) before 2003 to mid-August (8.452 ± 0.042 months) after 2003, along with an alarming increase in the amplitude of seasonal peaks in both CDC and CMS data. The lowest monthly reported cases of legionellosis in 2015 (281) exceed the maximum value reported before 2003 (206). We also observed a discrepancy between CDC and CMS data, suggesting that not all cases of legionellosis diagnosed by hospital-based laboratories were reported to the CDC. Improved reporting of legionellosis is required to better inform the public and organise disease prevention.

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.

Legionnaire\'s disease has been recognized as a cause of severe community-acquired pneumonia (CAP). Legionnaire\'s disease has characteristic extrapulmonary findings that are the basis for a presumptive clinical diagnosis. The widespread use of Legionella culture, sputum DFA, serology, urinary antigen testing, and polymerase chain reaction have allowed earlier diagnosis of Legionnaire\'s disease. Excluding common source outbreaks, CAP caused by Legionnaire\'s disease is manifested as sporadic cases. In contrast, nosocomial Legionnaire\'s disease occurs in clusters or outbreaks from common Legionella species-contaminated water sources. Improved diagnostic tests have permitted accurate diagnosis. Bacterial coinfections with Legionnaire\'s disease are uncommon, but when present, are most often associated with bacteremia pneumococcal pneumonia.