Diagnostic performance of Xpert MTB/RIF ultra in detecting Mycobacterium tuberculosis and Rifampicin Resistance in AFB Smear-negative Pulmonary and Extrapulmonary Tuberculosis samples in Malaysia.

Rapid and highly accurate diagnostic tools are critically needed to diagnose Mycobacterium tuberculosis and rifampicin resistance in AFB smear-negative samples. In this study, we evaluated the diagnostic performance of Xpert MTB/RIF Ultra (Ultra) as a rapid test to diagnose tuberculosis in smear-negative cases in Malaysia. A retrospective study of 1960 smear-negative pulmonary and extrapulmonary samples obtained from patients was conducted. Culture was used as the reference standard for the study. The overall sensitivity and specificity of Ultra on the tested samples were 88.7 % and 77.2 %, respectively, while the PPV was 32.3 % and the NPV was 98.2 %. Ultra showed slightly higher sensitivity in pulmonary (89.9 %) compared to extrapulmonary samples (86.1 %). The overall accuracy of Ultra was 78.5 % (kappa=0.37; 95 %CI: 0.32,0.42). Ultra showed good diagnostic accuracy for detecting MTB and rifampicin resistance in various AFB smear-negative samples. Ultra also had excellent capability in rifampicin resistance detection.

Predominance of the East-Asian Beijing genotype in a Mycobacterium tuberculosis drug-resistant population in Central Malaysia.

OBJECTIVES: Previous diversity studies on local Mycobacterium tuberculosis (MTB) isolates, with or without antibiotic resistance, showed predominance of Indo-Oceanic East African-Indian (EAI) strains. This study focused specifically on a drug-resistant MTB population from Central Malaysia and aimed to investigate the genotypes and resistance patterns involved. METHODS: Whole-genome sequencing was performed on 56 local MTB isolates with known rifampicin resistance or multidrug resistance towards 13 anti-TB agents. Analysis of each genome sequence was performed using the widely recognized online MTB genotyping platforms, TBProfiler and Mykrobe, to determine lineage and genotypic drug resistance profiles. RESULTS: Forty (71.4%) isolates were identified as East-Asian Beijing strains. Phenotypic to genotypic antibiotic resistance patterns differed in 33 isolates (58.9%), with one isolate showing extensive drug-resistance (XDR) previously not detected by conventional drug-susceptibility testing. CONCLUSION: This drug resistance population study demonstrated predominance of the East-Asian Beijing strains and a newly detected extensively drug-resistant MTB (XDR-TB) isolate in Malaysia. Information regarding the association between lineage and drug-resistant TB in Malaysia is scarce, and more studies are needed to determine the significance of such association, if any, in our local settings.

Characteristics of community- and hospital-acquired meticillin-resistant Staphylococcus aureus strains carrying SCCmec type IV isolated in Malaysia.

Community-acquired meticillin-resistant Staphylococcus aureus (CA-MRSA) occurring among hospital isolates in Malaysia has not been reported previously. As CA-MRSA reported worldwide has been shown to carry SCCmec types IV and V, the aim of this study was to determine the SCCmec types of MRSA strains collected in Malaysia from November 2006 to June 2008. From a total of 628 MRSA isolates, 20 were SCCmec type IV, whilst the rest were type III. Further characterization of SCCmec type IV strains revealed 11 sequence types (STs), including ST22, with the majority being ST30/Panton-Valentine leukocidin positive. Eight out of nine CA-MRSA were ST30, one was ST80, and all were sensitive to co-trimoxazole and gentamicin. Five new STs designated ST1284, ST1285, ST1286, ST1287 and ST1288 were discovered, suggesting the emergence of novel clones of MRSA circulating in Malaysian hospitals. The discovery of the ST22 strain is a cause for concern because of its ability to replace existing predominant clones in certain geographical regions.