Legionnaires\' disease is an atypical pneumonia caused by Legionella pneumophila. Legionella species are found in freshwater sources and are transmitted through inhalation of contaminated aerosols. Patients commonly present with fever, chills, and cough. However, in immunosuppressed patients or severe cases, the disease can lead to multiorgan failure. In recent years, the incidence of Legionnaires\' disease has drastically increased and unfortunately is commonly underdiagnosed. Gold-standard diagnosis is made through sputum cultures; however, urine Legionella antigen remains the most common test used for diagnosis. Goal-directed care includes antibiotics and supportive care. This case highlights a rare and unique presentation of Legionnaires\' disease presenting with an elevated 2:1 aspartate aminotransferase to alanine transaminase pattern, typically seen with alcoholic hepatitis.

BACKGROUND: Immunocompromised patients are at an increased risk of severe legionella infections. We present the results of an outbreak investigation initiated following a fatal case of hospital-acquired legionellosis linked to contaminated water from a toilet-flushing cistern. Additionally, we provide experimental data on the growth of Legionella spp. in flushing cisterns and propose a straightforward protocol for prevention.
METHODS: We monitored the growth of Legionella spp. in the building\'s hot- and cold-water systems using quantitative bacterial culture on selective agar. Molecular typing of Legionella pneumophila isolates from the infected patient and the water system was conducted through core-genome multi-locus sequence typing (cgMLST).
RESULTS: Legionella contamination in the hospital building\'s cold-water system was significantly higher than in the hot-water system and significantly higher in toilet flushing cistern\'s water compared with cold water from bathroom sinks and showers. Isolates from the patient and from the flushing cistern of the patient\'s bathroom were identical by cgMLST. In an experimental setting, daily toilet flushing for a period of 21 days resulted in a 67% reduction in the growth of Legionella spp. in the water of toilet flushing cisterns. Moreover, a one-time disinfection of cisterns with peracetic acid, followed by daily flushing, decreased legionella growth to less than 1% over a period of at least seven weeks in these setting.
CONCLUSIONS: One-time disinfection of highly contaminated cisterns with peracetic acid and daily toilet flushing as short-term measure can significantly reduce legionella contamination in flushing cisterns. These measures may aid in preventing legionella infection among immunocompromised patients.

Cold agglutinin syndrome (CAS) is a rare subset of autoimmune hemolytic anemia (AIHA) and can be classified as either primary or secondary. Secondary cold agglutinin disease has been associated with both viral and bacterial pathogens with the most common bacterial pathogen being Mycoplasma pneumoniae. Legionella pneumonia is a well-known causative agent for community-acquired pneumonia that can lead to a severe disease requiring hospitalization that is rarely associated with AIHA. We highlight the importance of recognizing Legionella pneumonia as a causative pathogen for CAS.

Although Legionnaires\' disease mainly affects the lungs, it can also present with other systemic involvement, including rare cardiac manifestations. Recognised presentations are endocarditis, myocarditis, pericarditis, and pericardial effusion. A 72-year-old British man presented with a six-day history of dry cough and a four-day history of fever during the peak of the COVID-19 pandemic. His electrocardiogram showed Mobitz type II atrio-ventricular block. Although all the cultures were negative, the chest X-ray demonstrated COVID-19 infection-like features. With high clinical suspicions and chest X-ray features, the polymerase chain reaction of the COVID tests was repeated three times and all were negative. He had a positive urinary Legionella antigen, and his bradycardia and heart block improved after treatment with amoxicillin/clavulanic acid, and clarithromycin. As the electrocardiogram showed Mobitz type II, a permanent pacemaker was implanted. The follow-up pacemaker check showed that he still required active pacing.

Legionnaires\' disease is a type of pneumonia caused by Legionella bacteria. This type of bacteria can be found anywhere across the world, mostly in moist environments (e.g., ground soil, rivers, lakes). More importantly, Legionella can multiply in water systems such as air conditioners, which is a common source of outbreaks nationwide, particularly during the summer months. We present a unique clinical course of Legionnaires\' disease with suspected underlying recurrent lung cancer in a 77-year-old man during an outbreak that originated in a small city near our hospital. The patient presented to Urgent Care and after initial assessment, was admitted to the Internal Medicine Unit. He underwent supportive treatment with antibiotic therapy and oxygen, and was discharged one week after admission with improvement. The patient returned to Urgent Care a few weeks later with worsening dyspnea, where he was then transferred to another hospital for admission to the Intensive Care Unit (ICU), and later died. We report this special case to bring awareness to physicians of the possibility and importance of early detection and prompt management of Legionnaires\' disease in lung cancer and critically ill patients with possible environmental risk factors. Prompt detection and management of Legionella pneumophila allows for a greater chance of a favorable prognosis, particularly in the immunocompromised.

Drug-induced liver injury (DILI) is the leading cause of acute liver failure in the United States. Azithromycin is a commonly used antibiotic for community-acquired pneumonia that causes liver injury in rare cases. Typically, cholestatic liver injury has been reported for azithromycin, but there have only been a few case reports addressing the association with direct hepatocellular liver injury. This is a case of a 66-year-old man, with no pre-existing liver disease, who was managed for Legionnaires\' disease who sustained a hepatocellular pattern of liver injury associated with azithromycin. We report this case to highlight the importance of prompt recognition of these rare side effects associated with azithromycin and the discontinuation of the drug to facilitate rapid recovery.

A rapid detection of Legionella bacteria in water samples is crucial to minimize the risk of acquiring infections, especially in health care facilities. Different detection methods and different decontamination procedures have been reported to affect the recovery of Legionella spp. Our goal was to test the recovery of Legionella pneumophila and Legionella non-pneumophila species using a kit based on non-specific and species-specific probes to treat water samples after two different decontamination procedures.
The study was conducted with samples collected in the teaching hospital \"Le Scotte\" of Siena (Italy). Waters samples were analyzed by: i) ScanVIT method after treatment with acids; ii) ScanVIT method after heating; and iii) cultural standard method after heating. The results of the decontamination procedures and the detection methods were evaluated by comparing the number of Legionella-positive and -negative samples, and the recovery rates (CFU l-1) obtained by ScanVIT and the standard method.
We find that ScanVIT method is highly sensitive with both decontamination treatments, yielding a higher recovery of L. pneumophila compared to the standard method. Conversely, ScanVIT associated with the acid-treatment yielded the highest recovery of L. non-pneumophila.
The acid-treatment combined to the ScanVIT method increases the recovery of L. non-pneumophila in water samples compared to both ScanVIT associated with heat-treatment and standard culture method. Thus, this method may represent the best choice to detect L. non-pneumophila in water samples and reduce the risk of infection due to underestimation of Legionella loads.

Legionella pneumophila is a causative agent of a severe pneumonia, known as Legionnaires\' disease. Legionella pathogenicity is mediated by specific virulence factors, called bacterial effectors, which are injected into the invaded host cell by the bacterial type IV secretion system. Bacterial effectors are involved in complex interactions with the components of the host cell immune and signaling pathways, which eventually lead to bacterial survival and replication inside the mammalian cell. Structural and functional studies of bacterial effectors are, therefore, crucial for elucidating the mechanisms of Legionella virulence. Here we describe the crystal structure of the LpiR1 (Lpg0634) effector protein and investigate the effects of its overexpression in mammalian cells. LpiR1 is an α-helical protein that consists of two similar domains aligned in an antiparallel fashion. The hydrophilic cleft between the domains might serve as a binding site for a potential host cell interaction partner. LpiR1 binds the phosphate group at a conserved site and is stabilized by Mn(2+), Ca(2+), or Mg(2+) ions. When overexpressed in mammalian cells, a GFP-LpiR1 fusion protein is localized in the cytoplasm. Intracellular signaling antibody array analysis revealed small changes in the phosphorylation state of several components of the Akt signaling pathway in HEK293T cells overexpressing LpiR1.