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).