DISCUSSION
According to the ATS (American thoracic society) and IDSA (infectious disease society of America) guidelines released in 2007, to identify NTM respiratory infection radiological, microbiological, and clinical findings are required. These include finding nodular or cavitary lesions on chest X-ray or bronchiectasis on HRCT and positive culture of at least two sputum specimens[6]. Most cases of M. szulgai  respiratory infection have been previously reported to be fibrocavitary[5]. whereas in our case was bronchiectasis with nodular lesions and a tree-in-bud view. In the bronchiectasis form, the disease is more scattered in the middle lobe and lingual area, whereas in our case most lesions were in the upper lobe. Lio et al. showed that the bronchiectasis form of Mycobacterium avium pulmonary infection is more commonly seen in those with chronic obstructive pulmonary disease or gastrointestinal malignancies such as gastroesophageal reflux disease[7]. Our patient had no history of any obstructive diseases or gastrointestinal malfunctions. In the majority of reported cases, M. szulgai  respiratory infections men over 50 years of age and have risk factors such as alcohol abuse, smoking, history of TB infection, low body mass index or skeletal abnormalities of the chest[8]. To our knowledge, the present patient is the youngest case of M. szulgai pulmonary infection without any underling disease with had severe vitamin D deficiency. Vitamins can affect different components of the innate immune system, and deficiencies lead to defects in the immune system and infections[9]. The normal blood level of vitamin D is about 30 ng/ml and vitamin D deficiency involves a blood level below 20 ng/ml. Douglas et al. demonstrated that vitamin D plays an important role in immunological defense against mycobacterial infections. Vitamin D activates macrophages by blocking the intera cellular growth of mycobacteria; on the other hand, vitamin D deficiency causes immune system defeat and growth Mycobacteria easily [11]. The main source of vitamin D for humans is sunlight [12]. Because the patient spent a lot of time at the workplace and no history of eating vitamin D supplements and Vitamin D rich diets, he had a severe vitamin D deficiency.
Unlike other NTM, M. szulgai is sensitive to most anti-TB drugs and responds well to treatment regimens containing more than two anti-TB drugs [6]. M. szulgai is also sensitive to macrolides aminoglycosides, and fluoroquinolones. In some reports, clarithromycin treatment with ethambutol and rifampicin or rifabutin has been found effective [7]. Clarithromycin is one of the famous members of aminoglycosides which has been FDA approved in 1990. This therapeutic agent is recommending for various bacterial infection particularly mycobacterial diseases [10]. According to review of the literatures, there are several evidence for successful treatment of clarithromycin in pulmonary infection caused by M. szulgai [11]. On a 10-month follow-up, the patient had a negative smear and culture. Signs of improvement in the patient’s chest X-ray visible (Fig. B).