Doubled Nontuberculous Mycobacteria Isolation as a Consequence of Changes in the Diagnosis Algorithm

Figures & data

Figure 1 Flowcharts of the two applied diagnostic procedures. (A) Procedure (I) L-J slant/MGIT960 with the PNB differential medium test; (B) Procedure II: MGIT960 with the MPT64 antigen test.

Abbreviations: L-J, Lowenstein–Jensen; PNB, p-nitrobenzoic acid; DST, drug susceptibility testing; NTM, nontuberculous mycobacteria; MTBC, Mycobacterium tuberculosis complex; AFB, acid-fast bacilli.

Table 1 NTM Isolations in the Two Different Procedures

Classification	Procedure I	Procedure II
Culture-positive cases	1005	1258
Priscribed DST/MPT64 cases	690	1258
Reported “MTBC”	618	1014
Reported “NTM”*	72	244
MTBC	0	8
NTM	67	151
Other bacteria	5	3
Without further result	0	82
NTM species composition
M. intracellulare	40	64
M. abscessus	12	28
M. kansasii	6	3
M. avium	3	17
M. paragordonae	0	8
Other rare NTM	6	20
NTM without species identification	0	11

Notes: *In procedure II, the reported “NTM” refers to isolates with AFB-positive results. Procedure I: L-J/MGIT960 combined with PNB differential growth test; Procedure II: MGIT960 combined with MPT64 antigen test.

Figure 2 NTM species/subspecies identified in the two applied procedures. (A) Species compositions in Procedure I; (B) Species compositions in Procedure II.

Figure 3 NTM identification rate in 2019–2021. The NTM identification rate equals the number of NTM identified divided by the total number of mycobacteria identified by PCR-sequencing.