<unk>  is a common atypical<unk>  caused by the bacterium M.<unk> e. In the USA, the incidence of<unk>  is approximately 600 per 100,000 individuals.<unk> e is transmitted through airborne droplets from person to person. M.<unk> e is primarily an extracellular pathogen that has evolved a specialized attachment organelle for close association with host cells. The organism's tropism for respiratory epithelial cells and its synthesis of hydrogen peroxide aid in the pathogenesis of<unk> .<unk>  must be differentiated from other causes of<unk> , chest pain, and cough, such as other infectious causes, aspiration<unk> ,<unk> is, lung abscess, empyema, COPD exacerbation, asthma, interstitial lung disease, cardiac diseases, and malignancies. Patients younger than 40 years of age (especially between 5 and 20 years of age) are more commonly affected with<unk> . In contrast,<unk>  is less common (but still incident) among children < 5 years of age or adults > 40-60 years of age. There is no gender predilection to the development of<unk> . The incidence of<unk>  is higher in regions with temperate climate during the Summer and Fall. Additional risk factors include living in closed communities (healthcare settings, prisoners, military, college students), active lung disease, immunocompromised status, history of sickle cell disease, and active smoking. Following transmission,<unk>  incubation period is approximately 1 to 4 weeks. During this time, the patient remains asymptomatic. Onset of symptoms can be gradual and subacute. If left untreated,<unk>  slowly progresses, and patients typically report high-grade fever, sore throat, headache, and a persistent dry cough. While the disease can persist for weeks or months, it is frequently mild and self-resolving.  In children < 5 years of age, the infection may run subclinical, mild, and non-pneumonia courses. Complications of<unk>  include otitis, hemolytic anemia, asthma exacerbation, bronchiectasis, Swyer-James syndrome (post-infectious obliterative bronchiolitis), acute kidney injury, Guillain-Barré syndrome, Stevens-Johnson syndrome, pericarditis, myocarditis, transverse myelitis, or meningoencephalitis. Prognosis is usually good, and the majority of patients recover completely even without antimicrobial therapy. Elderly individuals and patients with sickle cell disease and other immunocompromised patients are at increased risk of developing complications of<unk> .<unk>  is diagnosed by either culture, serology, or molecular methods. Antimicrobial therapy using either a macrolide, doxycycline, or a fluoroquinolone is the mainstay of therapy for atypical<unk>  caused by<unk> . There is no vaccine against<unk> , but avoiding infected individuals helps reduce risk of infection.
Mycoplasma pneumonia
Chlamydophila pneumoniae
Mycobacterium tuberculosis
Burkholderia pseudomallei
Pneumocystis jirovecii
Bacillus anthracis
Rhodococcus equi
Legionella