After isoniazid and rifampin (rifampicin), the next pivotal drug class in Mycobacterium tuberculosis treatment is the fluoroquinolone class. Mutations in resistance-determining regions (RDR) of the rpoB, katG, and gyrA genes occur with frequencies of 97%, 50%, and 85% among M. tuberculosis isolates resistant to rifampin, isoniazid, and fluoroquinolones, respectively. Sequences are highly conserved, and certain mutations correlate well with phenotypic resistance. We developed a pyrosequencing assay to determine M. tuberculosis genotypic resistance to rifampin, isoniazid, and fluoroquinolones. We characterized 102 M. tuberculosis clinical isolates from the Philippines for susceptibility to rifampin, isoniazid, and ofloxacin by using the conventional submerged-disk proportion method and validated our pyrosequencing assay using these isolates. DNA was extracted and amplified by using PCR primers directed toward the RDR of the rpoB, katG, and gyrA genes, and pyrosequencing was performed on the extracts. The M. tuberculosis H37Rv strain (ATCC 25618) was used as the reference strain. The sensitivities and specificities of pyrosequencing were 96.7% and 97.3%, 63.8% and 100%, and 70.0% and 100% for the detection of resistance to rifampin, isoniazid, and ofloxacin, respectively. Pyrosequencing is thus a rapid and accurate method for detecting M. tuberculosis resistance to these three drugs.Rifampin (rifampicin), isoniazid, and the fluoroquinolones are the most important initial drug markers for extensively drug-resistant Mycobacterium tuberculosis strains, defined as multidrug-resistant (MDR) isolates (resistant to both isoniazid and rifampin) with additional resistance to a fluoroquinolone and to one of the injectable drugs (2). The fluoroquinolones have become an essential part of treatment regimens for MDR tuberculosis (7,25). Due to their potency and safety, the newgeneration fluoroquinolones are now even being evaluated as first-line medications for tuberculosis (3,13,20). Wang et al. further suggested that routine fluoroquinolone resistance testing may have a clinical impact by showing a significant correlation between development of fluoroquinolone and first-line M. tuberculosis drug resistance in an area in which resistant strains are highly endemic (28).The spontaneous acquisition of DNA sequence mutations is the primary genetic basis for the development of M. tuberculosis drug resistance (14). Since sequences are highly conserved, certain mutations correlate well with phenotypic resistance, and a limited number of mutations account for the majority of phenotypic resistance to the important antituberculosis medications, various methods of genotypic testing have successfully been used for the rapid detection of M. tuberculosis resistance (16,22). The sites that most frequently contain mutations associated with phenotypic resistance, called resistance-determining regions (RDR), differ depending on the drug tested. Among rifampin-resistant isolates worldwide, 95 to 97% harbor mutations in the rifampin RDR, an 81-bp ...

Background: Pulmonary tuberculosis (PTB) and paragonimiasis remain as health problems in certain areas in the Philippines. Both share similar clinical manifestations, which include chronic productive cough, hemoptysis, dyspnea, fever, weight loss, and night sweats. This study aimed to determine the prevalence of PTB, paragonimiasis, and co-infections in Zamboanga del Norte, Philippines. Methods: This study was conducted in selected villages in two municipalities in Zamboanga del Norte. Patients with chronic cough were interviewed, examined, and requested to submit two sputum samples which were processed using Ziehl-Neelsen method to detect acid-fast bacilli (AFB), and NaOH concentration technique for the detection of Paragonimus ova. Results: A total of 836 patients submitted sputum samples for examination. Prevalence was 6.7% (2.5-12.7%) for paragonimiasis and 1.9% (0.9-6.3%) for PTB. Co-infection rate was 0.3%, with two identified cases. Positivity rates for males and females were 9.6 and 5.8% for paragonimiasis and 3.4 and 1.2% for PTB. Conclusion: Pulmonary tuberculosis and paragonimiasis are co-endemic in Zamboanga del Norte, suggesting the need to integrate surveillance and control efforts. Strengthening local health systems through collaboration between different sectors is recommended for effective disease control. Development of more sensitive diagnostic tests is important for more accurate disease surveillance.

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An MPT64 antigen detection assay, the SD Bioline TB Ag MPT64 Rapid kit, was evaluated for the identification of Mycobacterium tuberculosis grown in both solid and liquid media. The rapid test showed positive results in 132 of 133 (99.2%) M. tuberculosis cultures grown on Ogawa medium and 136/143 (95.1%) cultures grown in liquid culture medium, resulting in an overall sensitivity of 97.1%. All 18 non-tuberculous mycobacteria were found to be negative by the rapid test, indicating a specificity of 100%. The rapid test seems useful for the initial confirmation of M. tuberculosis in acidfast bacilli positive cultures.

Setting The 3rd national tuberculosis (TB) survey in the Philippines in 2007 reported a significant decline in the prevalence of TB. Since then, more significant investments for TB control have been made, yet TB burden estimates from routine surveillance data remain relatively stable. Objective To estimate the prevalence of bacteriologically confirmed pulmonary TB in the Philippines amongst individuals aged ≥15 years in 2016. Design In March–December 2016, we conducted a population-based survey with stratified, multi-stage cluster sampling of residents in 106 clusters aged ≥15 years. Survey participants were screened for TB by symptom-based interview and digital chest X-ray. Those with cough ≥2 weeks and/or haemoptysis and/or chest X-ray suggestive of TB were requested to submit 2 sputum specimens for Xpert MTB/RIF, direct sputum smear microscopy using LED fluorescent microscopy, and mycobacterial solid culture (Ogawa method). Bacteriologically confirmed pulmonary TB was defined as MTB culture positive and/or Xpert positive. Results There were 46,689 individuals interviewed, and 41,444 (88.8%) consented to a chest X-ray. There were 18,597 (39.8%) eligible for sputum examination and 16,242 (87.3%) submitted at least one specimen. Out of 16,058 sputum-eligible participants, 183 (1.1%) were smear-positive. There were 466 bacteriologically confirmed TB cases: 238 (51.1%) Xpert positive, 69 (14.8%) culture positive, and 159 (34.1%) positive by both Xpert and culture. The estimated TB prevalence per 100,000 population aged ≥15 years was 434 (95% CI: 350−518) for smear-positive TB, and 1,159 (95% CI: 1,016−1,301) for bacteriologically confirmed TB. Conclusion This nationally representative survey found that the TB burden in the Philippines in 2016 was higher than estimated from routine TB surveillance data. There was no evidence of a decline in smear and culture positive TB from the 2007 survey despite significant investments in TB control. New strategies for case-finding and patient-centered care must be intensified and expanded.