Background: Mycoplasmal pneumonia is a common type of adult communityacquired pneumonia in China, but round/spherical pneumonia caused by mycoplasma pneumoniae has rarely been reported. Here, we report an outbreak of mycoplasmal round pneumonia in a military dormitory in China. Methods: We analysed epidemiological, clinical, imaging and laboratory data from a series of adults affected by an outbreak of mycoplasmal round pneumonia in the dormitory of a military hospital (Fuzhou General Hospital) in Fuzhou, China. The dormitory included 2 separate buildings. Mycoplasma antibody was detected using a passive agglutination assay. Results: The first case in our series, a 23-year-old male intern, presented on July 16, 2015 with a 3-day history of low-grade fever, dizziness, fatigue and chest tightness.Chest computed tomography revealed spherical masses. Over the following 4 days, 11 individuals who had been in close contact with the first patient were found to have similar masses. All 12 cases were mildly symptomatic or asymptomatic, and fever was the only sign visible upon physical examination. Chest radiology revealed single, round consolidations in 3 cases and multiple round consolidations in 9 cases; consolidations ranged in size from 0.2 to 2.9 cm. Most cases had normal blood cell count, erythrocyte sedimentation rate and C reactive protein level. Nasopharyngeal swabs from all cases tested negative for 25 pathogens, including Mycoplasma pneumoniae, in a PCR-based assay performed on August 1, 2015. All 12 patients showed a 4-fold increase in the titre of anti-mycoplasmal pneumonia antibody in paired sera on August 13, 2015. Patients were given the antibiotic moxifloxacin or symptomatic treatment, and 11 of the 12 cases showed complete resolution of round pneumonia lesions within 4 weeks. Conclusion: This case series illustrates the diversity of clinical manifestations as well as imaging findings for mycoplasmal pneumonia, to which clinicians should pay more attention. Mycoplasmal round pneumonia should be included in differential diagnosis of multiple pulmonary nodules in adults in order to enable accurate clinical identification of disease and successful treatment and resolution. K E Y W O R D S adult, mycoplasmal pneumonia, outbreak, round pneumonia 2660 | WEN et al. How to cite this article: Wen W, Gu L, Yu GQ, et al. Outbreak of mycoplasmal round pneumonia in an adult population: A case series. Clin Respir J.
