Microsoft word - varilla_psbmb2010[1].doc

Sample Abstract for PSBMB 2010 Poster Presentation DETECTION OF MUTATIONS IN ISONIAZID RESISTANT MYCOBACTERIUM
TUBERCULOSIS ISOLATES FROM TB PATIENTS IN THE PHILIPPINES
Vincent M. Varilla1, Sharie Keanne C. Ganchua2, Concepcion F. Ang3, Myrna T. Mendoza3, Raul V. Destura2 and Francisco M. Heralde III4 1College of Medicine, University of the Philippines-Manila, Philippine General Hospital 2Institute of Molecular Biology and Biotechnology, National Institutes of Health, University of 3Infectious Diseases Section, Department of Medicine, Philippine General Hospital 4Department of Biochemistry and Molecular Biology, College of Medicine, University of the ABSTRACT

Introduction
Drug-resistant tuberculosis is a significant clinical and epidemiologic dilemma, with disease burden reaching 8 million new cases annually and 1.7 million deaths per year.
Resistance to first-line drugs like isoniazid (INH) threatens management and cure. INH
resistance is associated with katG, a gene encoding for catalase-peroxidase and involved in
INH conversion to bioactive form. This study aimed to detect the katG mutations in local TB
isolates and describe them in comparison with findings elsewhere.

Methodology
Thirty seven TB isolates from patients of PGH were utilized. Phenotype referencing and antimicrobial drug susceptibility tests (ADST) were previously performed by the IDS-
PGH using CDC standard procedures. katG gene segment was amplified and PCR product
sequenced and compared with wild type H37Rv (ATCC 25618).

Major Findings
The results confirmed early findings regarding katG mutation in codon 315, with most mutations being AGCACC (Ser to Thr). The results show disparity between the number of
phenotypically resistant isolates (89.2%) and the number of actual mutations located in katG
sequences (59.4%), pointing to either new mutation regions of katG gene or the occurrence
of mutations in other INH resistance associated genes. The isolates showed country-specific
variation (e.g., the absence of mutations in codon 309 and occurrence of novel mutation in
codon 333 (Leu to Arg). Multiple mutations were not found in any Philippine isolate studied,
unlike those in Europe and particularly Belarus, suggesting a possibly lowered secondary
infection rate of local TB patients.

Conclusion/Recommendation
The study showed the mutation profile similarities and differences of INH resistant strains from the Philippines with elsewhere based on literature. The results also suggest
involvement of other genes in INH resistance of local TB isolates. Further studies need to be
done on the entire katG gene or to other INH associated resistance genes in order to
account for the observed phenotype.
Keywords: INH-resistance, katG mutation, tuberculosis

Source: http://www.bic.searca.org/events/2010/psbmb2010/sampleabstract.pdf