Identification of non-tuberculous mycobacteria isolated from clinical specimens at a tertiary care hospital: a cross-sectional study

Abstract

BackgroundNon-tuberculous mycobacteria (NTM) are opportunistic pathogens in immuno-compromised patients. They are also increasingly recognized as pathogens in immuno-competent individuals. Globally, an increase in NTM isolation is being reported with a varied geographic prevalence of different species around the world. There is lack of data on species distribution of these organisms from Pakistan. Treatment options differ according to the species isolated and its susceptibility profile. Knowledge of local species variation would help targeted therapy. This study was performed to determine frequencies of different NTM species isolated from various clinical specimens submitted at a tertiary care hospital laboratory.MethodsNTM isolated from 25955 clinical specimens over a period of two years (2010 to 2011) were included. All NTM were identified using conventional tests. Drug susceptibility testing (DST) was performed by broth microdilution and interpreted according to Clinical and Laboratory Standards Institute’s document M24-A2.ResultsA total of 104 NTM were included in the study. Of these, 76% (54/71) rapidly growing mycobacteria (RGM) and 57.6% (19/33) slow growing mycobacteria (SGM) could be further identified. Mycobacterium fortuitum (21/54) was the commonest NTM identified among RGM followed by M. mucogenicum (12/54) and M. smegmatis (11/54). Among SGM, M. avium complex (MAC) was the most frequent (14/19). Clinical significance could be assessed in a limited number (52/104) of NTM isolates and MAC appeared to be the commonest significant NTM. Three extra-pulmonary cases were found to be healthcare associated infections. DST results for RGM showed susceptibility to amikacin (100%), clarithromycin (100%, except M. fortuitum where it is not reportable), linezolid (90%) and moxifloxacin (75%). Whereas SGM were susceptible to clarithromycin (100%), linezolid (58.8%) and moxifloxacin (64.7%).ConclusionThis is the first study reporting NTM species and their clinical significance isolated from clinical specimens from Pakistan. Isolation of NTM from clinical specimens should prompt to evaluate their clinical significance.

Non-tuberculous mycobacteria profiles and their anti-mycobacterial resistance at a major medical center in Lebanon

“…In relation to MAC, the 86% susceptibility rate to clarithromycin among the tested isolates in this current study from Lebanon was close to that reported from different parts of the world: USA (99%) [29], England (80%) [27] , Sweden (97%) [30], China (91%) [31], Japan (75%) [32], Taiwan (93%) [33], as well as Pakistan [34] and India (100%, each) [35]. Variation, however, was observed among the susceptibility rates of moxifloxacin and linezolid.…”

“…However, relatively susceptible isolates were reported from Greece (36%) [36], USA (<50%) [37], Netherlands (78%) [28] and China (86%) [31]. Such a wide range of variation in susceptibility was also noted for linezolid: current study from Lebanon (0%), Greece (4%) [36] Taiwan (13%) [33], Sweden (16%) [30], USA (<50%) [37], Pakistan (67%) [34] and China (93%) [31].…”

“…The M. abscessus susceptibility rates in our study showed a wide range of variation among the 11 tested antimicrobials (Table 3), with noted susceptibility only to amikacin and clarithromycin. The 67% clarithromycin susceptibility rate among the isolates from Lebanon was higher than the 15% and 20% reported from Korea [38] and Iran [26], respectively, close to that reported from Netherlands (62%) [28], but lower than the susceptibility rates reported from Turkey (86%) [39], UK (94%) [40], China (95%) [31], Japan (80%) [41], Pakistan (100%) [34] and Taiwan (93%) [42]. On the other hand, the 100% susceptibility to amikacin in the current study was comparable to that reported from the aforementioned countries (86%-100%) except for that reported from Netherlands (5%) [28] and Korea (68%) [38].…”

“…For example, the uniform resistance to moxifloxacin among the current isolates from Lebanon mirrored the susceptibility rate reported in Taiwan (4%) [33]. Very low susceptibility rates were also reported from Sweden (15%) [30] and Pakistan (17%) [34]. However, relatively susceptible isolates were reported from Greece (36%) [36], USA (<50%) [37], Netherlands (78%) [28] and China (86%) [31].…”

Non-tuberculous mycobacterial infections—A neglected and emerging problem

“…An earlier study evaluating the distribution of NTM species across Pakistan suggested geographical variation across different regions, every area having its own distribution spectrum (Ahmed et al, 2013). The differences were especially discernible between urban centres where access to bronchoscopy and more in-depth diagnostic efforts contribute to the detection of a larger number of NTM cases.…”