PMC6838927_01
Chest image of the case patient.. (A) Chest X-ray image shows a reticular shadow in the right upper lung field (arrowhead) and pleural calcification of the left lobe, along with volume reduction. (B, C) Chest high-resolution CT (HRCT) showed centrilobular micronodules in the right upper lobe and pleural calcification of the left lung, along with volume reduction.
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A chest X-ray image showed a reticular shadow in the right upper lung field and pleural calcification of the left lung along with volume reduction (Fig. 1). A chest high-resolution computed tomography (HRCT) scan revealed moderately thickened bronchial walls in the upper right bronchus, centrilobular micronodules in the upper right lobe, infiltration in the right middle lobe, and pleural calcification of the left lung along with volume reduction (Fig. 1).
Partial alignment of 16S rRNA sequences.. Partial alignment of 16S rRNA sequences of Mycobacterium triplex (M. triplex), M. florentinum, M. stomatepiae, and M. montefiorense. Dots indicate nucleotide identity and dashes indicate deletions. Reference sequence accession numbers are as follows: M. triplex: AJ276890; M. florentinum: NR042223; M. stomatepiae: HM022202; and M. montefiorense: NR028808. The similarity scores are: 1543 (M. triplex), 1543 (M. florentinum), 1531 (M. stomatepiae), and 1526 (M. montefiorense).
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Our results identified 2 species of NTM (M. triplex and M. florentinum) as superior candidates; however, they had the exact similarity score (Fig. 2).
Partial alignment of hsp65 sequences.. Partial alignment of hsp65 sequences of Mycobacterium triplex (M. triplex), M. florentinum, and M. lentiflavum. Dots indicate nucleotide identity and dashes indicate deletions. Reference sequence accession numbers are as follows: M. triplex: AFP-000NM44; M. florentinum: DSM44852; and M. lentiflavum: FJ06136. The similarity scores are: 686 (M. triplex), 654 (M. florentinum), and 652 (M. lentiflavum).
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Therefore, we sequenced the hsp65 gene of the NTM isolate (Fig. 3), which resulted in a similarity score of 686 for M. triplex and 652 for M. florentinum.
Timing of diagnostic tests and clinical course of the case patient.. AFB: Acid-fast bacilli, CLR: Clarithromycin, DDH: DNA-DNA hybridization, LVX: Levofloxacin, RIF: Rifampicin.. Low-dose clarithromycin (CLR) monotherapy was started in December 2012. An expectorated sputum culture for acid-fast bacilli (AFB) became positive in September 2013, but the species could not be identified by DNA-DNA hybridization (DDH) method. In March 2014, CLR dose was increased and rifampicin (RIF) was added because sputum smear for the AFB also became positive and pulmonary shadow gradually worsened. However, the positive results persisted in both smear and culture for AFB, the species of which DDH method still failed to identify. DNA sequencing analysis could identify one of these strains as M. triplex. After the initiation of levofloxacin (LVX) in December 2014, both smear and culture for AFB became negative and chest CT images showed reduction of pulmonary shadow gradually.
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Fig. 4 shows the clinical course of the present case including expectorated sputum smear and culture, identification results of bacterial species, chest CT images, and treatment details.