Legionnaires\' disease is a potentially severe type of pneumonia most often caused by the organism Legionella pneumophila. Exposure to this bacterial pathogen typically happens in the community but may also occur in the hospital setting. This report describes the case of a patient who presented due to 10 days of fever, shortness of breath, and diarrhea, with initial imaging demonstrating multifocal pneumonia. The patient was appropriately started on empiric antibiotics for community-acquired pneumonia and admitted to the medicine floor. The patient showed no meaningful improvement in his initial hospital course on empiric antibiotics with continued oxygen requirements. Meanwhile, urine Legionella antigen testing returned positive on hospital day four, and after tailoring antibiotics accordingly, the patient\'s clinical status improved significantly. This case report highlights the efficacy of broad testing in the initial admission and the need for constant re-evaluation in the context of a patient not improving with appropriate therapy.

Legionella, one of the main pathogens that causes community-acquired pneumonia, can lead to Legionella pneumonia, a condition characterized predominantly by severe pneumonia. This disease, caused by the bacterium Legionella pneumophila, can quickly progress to critical pneumonia and is often associated with damage to multiple organs. As a result, it requires close attention in terms of clinical diagnosis and treatment. Omadacycline, a new type of tetracycline derivative belonging to the aminomethylcycline class of antibiotics, is a semi-synthetic compound derived from minocycline. Its key structural feature, the aminomethyl modification, allows omadacycline to overcome bacterial resistance and broadens its range of effectiveness against bacteria. Clinical studies have demonstrated that omadacycline is not metabolized in the body, and patients with hepatic and renal dysfunction do not need to adjust their dosage. This paper reports a case of successful treatment of Legionella pneumonia with omadacycline in a patient who initially did not respond to empirical treatment with moxifloxacin. The patient also experienced electrolyte disturbance, as well as dysfunction in the liver and kidneys, delirium, and other related psychiatric symptoms.

UNASSIGNED: Postoperative Legionella pneumonia is very rare.
UNASSIGNED: A 71-year-old male patient with prostate cancer (cT2bN0M0) underwent a robotic-assisted radical prostatectomy. On the 5th postoperative day, the patient developed chills and a fever of 39.2°C. Chest radiography revealed decreased permeability in the right middle lung field, leading to the diagnosis of postoperative pneumonia. Antimicrobial therapy was initiated immediately. Blood tests on postoperative day 10 revealed mild liver function abnormalities, electrolyte abnormalities, and a markedly elevated inflammatory response. Legionella pneumonia was suspected based on blood sample results and systemic symptoms, such as diarrhea and nausea. Furthermore, Legionella antigens were detected in the patient\'s urine, prompting further administration of levofloxacin. The patient\'s subsequent clinical course was favorable.
UNASSIGNED: When bacterial pneumonia fails to respond to antimicrobial therapy and systemic symptoms develop, atypical pneumonia, caused by pathogens such as Legionella pneumophila, should be considered even in cases of postoperative pneumonia.

Legionella pneumonia (LP) is a relatively uncommon yet well-known type of atypical community-acquired pneumonia (CAP). It is characterized by a rapid progression to severe pneumonia and can be easily misdiagnosed. In most patients, chest computed tomography (CT) showed patchy infiltration, which may progress to lobar infiltration or even lobar consolidation. While pulmonary cavities are commonly observed in immunocompromised patients with LP, they are considered rare in immunocompetent individuals. Herein, we present a case of LP in an immunocompetent patient with multiple cavities in both lungs. Pathogen detection was performed using metagenomic next-generation sequencing (mNGS). This case highlights the unusual radiographic presentation of LP in an immunocompetent patient and emphasizes the importance of considering LP as a possible diagnosis in patients with pulmonary cavities, regardless of their immune status. Furthermore, the timely utilization of mNGS is crucial for early pathogen identification, as it provides multiple benefits in enhancing the diagnosis and prognosis of LP patients.

Legionella is an aerobic, gram-negative, intracellular pathogen and is an important cause of community-acquired pneumonia. Legionella pneumophila is the most common causative agent of Legionella pneumonia. Clinical diagnosis of Legionella pneumonia is challenging due to the lack of specific clinical manifestations and the low positive rates of conventional pathogen detection methods. In this study, we report a case of a patient with chronic myeloid leukemia who developed rigors and high fever after chemotherapy and immunotherapy. Chest computed tomography revealed consolidation in the left lower lobe of the lung and ground-glass opacities in both lower lobes. Multiple blood cultures showed Escherichia coli, Staphylococcus aureus, Bacillus licheniformis, and positive results in the β-D-glucan test (G test). The patient was treated with various sensitive antimicrobial agents, including meropenem plus fluconazole, meropenem plus carpofungin, and vancomycin. Unfortunately, the patient\'s condition gradually worsened and eventually resulted in death. On the following day of death, metagenomic next-generation sequencing (mNGS) of 1whole blood revealed L. pneumophila pneumonia with concurrent bloodstream infection (blood mNGS reads 114,302). These findings suggest that when conventional empirical antimicrobial therapy proves ineffective for critically ill patients with pneumonia, the possibility of combined Legionella infection must be considered, and mNGS can provide a diagnostic tool in such cases.

Legionnaires\' disease is an atypical pneumonia caused by Legionella pneumophila (L. pneumophila) pneumonia that features slow onset, nonproductive cough, fatigue, headache, sore throat, myalgias, and malaise. It can be difficult to diagnose, as it presents with extrapulmonary symptoms, and delay in treatment can be fatal. Here, we present the case of a previously healthy 32-year-old Caucasian male with Legionnaires disease who only presented to the clinic with abdominal pain and diarrhea. The patient did not have any pulmonary symptoms at the initial presentation. This presentation did not fit the diagnostic tools available for Legionnaires\' disease, including a validated clinical prediction rule, which ruled out L. pneumophila infection with a sensitivity of 97% and a negative predictive value of 99.4%. Due to the complaint of abdominal pain, a flat/upright abdominal X-ray was ordered, which includes a chest X-ray. Upon analyzing the chest X-ray, a right lower lobe consolidation was identified, prompting an L. pneumophila urinary test to be added to the lab orders. This case represents the difficulties in diagnosing Legionnaires\' disease due to the diverse clinical complexities of presentations, which may solely involve abdominal complaints.

Legionellosis among welders and other metalworkers is a rare but potentially underappreciated occupational hazard. The same mechanisms that predispose welders to severe pneumonia from Streptococcus pneumoniae and Bacillus cereus may similarly predispose them to Legionella pneumophila infection. We present a case of a previously healthy, immunocompetent 31-year-old male welder presenting with three days of shortness of breath, hypoxia, high-grade fever, and blood-tinged sputum. Chest computed tomography (CT) revealed a lobar consolidation of the right middle and lower lobes. Laboratory evaluation showed borderline hyponatremia, hypophosphatemia, and elevated liver enzymes. The patient was ultimately intubated and started on broad-spectrum antibiotics. Multiple respiratory cultures were negative and Legionella urine antigen testing was also negative. Eventually, bronchial Legionella culture was positive for Legionella pneumophila, and a blood next-generation sequencing test also confirmed the diagnosis. He was extubated six days following admission and subsequently discharged.

Legionnaires\' disease caused by the bacteria Legionella pneumophila, is considered a type of atypical pneumonia. The disease usually presents with dyspnea, cough, fever, muscle aches, headache, nausea, and vomiting. A milder form of the disease (Pontiac fever) with flu-like illness also exists. In addition to lung infection, extrapulmonary manifestations might occur including sepsis, rhabdomyolysis, neurological impairment, kidney, and liver damage. Myocarditis can be seen as a rare complication in Legionnaires\' disease. Here, we are presenting a case of Legionnaires\' disease associated with myocarditis in a patient with no predisposing risk factors for severe illness.

Legionella pneumonia, rhabdomyolysis, and acute kidney injury are called the Legionella triad, which is rare and associated with a poor outcome and even death. Early diagnosis and timely treatment are essential for these patients.
A 63-year-old man with cough, fever, and fatigue was initially misdiagnosed with common bacterial infection and given beta-lactam monotherapy but failed to respond to it. Conventional methods, including the first Legionella antibody test, sputum smear, and culture of sputum, blood, and bronchoalveolar lavage fluid (BALF) were negative. He was ultimately diagnosed with a severe infection of Legionella pneumophila by metagenomics next-generation sequencing (mNGS). This patient, who had multisystem involvement and manifested with the rare triad of Legionella pneumonia, rhabdomyolysis, and acute kidney injury, finally improved after combined treatment with moxifloxacin, continuous renal replacement therapy, and liver protection therapy.
Our results showed the necessity of early diagnosis of pathogens in severe patients, especially in Legionnaires\' disease, who manifested with the triad of Legionella pneumonia, rhabdomyolysis, and acute kidney injury. mNGS may be a useful tool for Legionnaires\' disease in limited resource areas where urine antigen tests are not available.

UNASSIGNED: Although Legionella is not the most common pathogen of community-acquired pneumonia, the epidemiological distribution of pneumonia pathogens has changed in recent years, with a gradual increase in some rare pathogens. For example, pneumonia that occurs after water source contamination is mostly caused by Legionella infection. This paper reports the diagnosis and treatment process of a patient after Legionella infection, who had misdiagnosis at the beginning, rapidly progressed to severe disease and combined with fungal infection. This article focuses on the timely and effective treatment of rapidly progressing Legionella pneumonia, in anticipation of a better understanding of the diagnosis and treatment of the disease.
UNASSIGNED: Here, we report a case of legionella infection with the nausea, vomiting as the first symptoms accompanied by weakness, chills, dizziness, abdominal discomfort in a 75-year-old female. The patient had a history of type 2 diabetes for 30 years, diabetic peripheral neuropathy for more than 20 years, arterial hypertension for 10 years, bone hyperplasia for more than 5 years, resection of right-sided thyroid cystadenoma in 1990. The patient had firstly been diagnosed with cholecystitis and gallbladder neck stones, diet abstinence, metronidazole, cefoperazone sulbactam, and rehydration were given. The patient responded poorly to these empiric treatments. The patient was given moxifloxacin in combination with azithromycin after the onset of respiratory symptoms, but the condition continued to deteriorate, and tigecycline was subsequently added. After the mechanical ventilation and the treatment plan adjusting, she improved significantly.
UNASSIGNED: Immunocompromised patient combined with underlying diseases are more susceptible to infection in an environment contaminated with Legionella, and the rapid onset and atypical respiratory symptoms make it easy to misdiagnose the disease, thus delaying treatment and leading to further deterioration. Timely diagnosis, early mechanical ventilation and rational drug administration were fundamental to treat Legionella pneumonia.