Case report: Mycobacterium monacense isolated from the blood culture of a patient with pulmonary infection

BACKGROUND: The poorly known mycobacterial species Mycobacterium monacense is a rapidly growing non-tuberculous mycobacterium that was first described in 2006 (Reischl et al., Int J Syst Evol Microbiol 56:2575-8, 2006); it has been reported that its isolation is usually associated with skin and lung infections, especially in immunosuppressed patients (Hogardt et al., Jpn J Infect Dis 61:77-8, 2008; Taieb et al., J Hand Surg Am 33:94-6, 2008; Therese et al., Lung India 28:124-6, 2011; Shojaei et al., Ann Lab Med 32:87-90, 2012; Romero et al., New Microbes New Infect 10:112-5, 2016 ). The clinical significance of Mycobacterium monacense is not yet fully understood. Here, we report the first isolation of Mycobacterium monacense from the blood culture of a patient in China with severe pneumonia. CASE PRESENTATION: On June 26, 2018, a 38-year-old man was admitted to the intensive care unit with breathing difficulty. One day prior, he was discovered with his face immersed in a small pond (non-chlorinated water) and with limb convulsions. He had undergone craniocerebral surgery after trauma 5 years earlier, which left him with epilepsy as a sequela. Bilateral diffuse ground-glass opacity was found in the lungs on chest X ray and chest CT image at admission. The result of the HIV serology test of the patient was negative. The patient was diagnosed with severe pneumonia. Drug-susceptible Klebsiella pneumoniae and Candida glabrata were isolated in the BALF, and yellow-pigmented colonies were isolated from blood cultures of the patient. The strain isolated from blood was identified by 16S rDNA sequencing as Mycobacteria monacense, which is a rapidly growing mycobacterium (RGM). The patient was treated with a combination of cefoperazone sulbactam, linezolid and voriconazole for 10 days, and the symptoms improved. During the one-year follow-up time, the patient did not relapse. CONCLUSIONS: We report the first case of M. monacense isolated from blood cultures in a patient with severe pneumonia, which provided evidence that the environmental microorganism possessed pathogenic characteristics.