Aims: Tuberculosis and other mycobacterial infections occur worldwide especially in patients with immunodeficiency. Typically, an empirical treatment for disseminated disease is required for initial therapy due to slow growing nature of most mycobacterial species. Therefore, species distribution and average time to positivity of blood culture is crucial. However, such information is limited for blood culture and, therefore, were determined. Methodology and results: The blood culture data using the BACTEC FX system and drugs susceptibility testing (DST) pattern was recovered during 2012-2017 from a large teaching hospital in Bangkok, Thailand. Overall, 7.8% of 4,838 blood and 6.4% of 1,056 bone marrow (BM) samples were positive for mycobacterial growth. Mycobacterium tuberculosis complex (MTBC), M. avium, and M. abscessus, were the most three common species to be isolated from blood (3.8%, 2.1%, and 0.9%, respectively) and BM (2.4%, 2.4%, and 0.9%, respectively). The average time to positivity for MTBC, M. avium, and M. abscessus was 25.7, 16.1, and 3.8 days, respectively. From 209 antimycobacterial susceptibility testing (AST)-available MTBC strains, 6 (2.87%) strains were multi-drugs resistant (MDR-TB). From 35 AST-available M. avium complex (MAC) isolates, 6 (17.14%), 33 (94.29%), and 28 (80%) isolates were resistant to clarithromycin, moxifloxacin, and linezolid, respectively. BM MAC isolates were significantly more resistant to clarithromycin than the blood isolates (44.5% vs 7.69%; p= 0.027). Conclusion, significance and impact of study: In summary, an emergence of M. abscessus and unusually high moxifloxacin and linezolid resistance of MAC isolates were reported in this study. Additional information of this study benefits physicians for anti-mycobacterial drug selection for initial treatment of mycobacteremia while blood and BM culture is pending.

Aims: Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is increasingly used to identify Candida spp. in diagnostic laboratories due to its strength in providing accurate information results, speed and cost-effectiveness. However, its accuracy varies on instrument platform, reference database, sample preparation techniques and interlaboratory comparisons. Therefore, the use of MALDI-TOF MS for species identification was evaluated against traditional biochemical identification, namely BrillianceTM Candida and Remel RapIDTM Yeast Plus System. Methodology and results: To evaluate and compare identification efficiency, turnaround time and consumable cost, 194 clinical isolates of Candida were collected. The results showed overall 85.6% concordant identification between two methods with 94.9-99.5% and 100% accuracy in traditional and MALDI-TOF MS, respectively, in the identification of four common Candida species; C. albicans, C. tropicalis, C. parapsilosis sensu stricto and C. glabrata sensu stricto. Other Candida species were also identified with 85.6% and 97.5% accuracy rates by traditional and MALDI-TOF MS, respectively. Additionally, identification using MALDI-TOF MS reduced overall turnaround time and cost by approximately 99.8% and 86.5%, respectively. Conclusion, significance and impact of study This study highlights the performance of MALDI-TOF MS, which is more accurate in identifying Candida spp. with a less hands-on approach, cheaper cost and shorter turnaround time.
Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization ; Candida ; Tertiary Care Centers