Posters
Presentation Type
Poster
Discipline Track
Translational Science
Abstract Type
Research/Clinical
Abstract
Purpose: Populations along the U.S.-Mexico border have a high prevalence of risk factors for TB such as low socioeconomic status, overcrowding and migration, and consequently, higher TB incidence (up to 12 and 44/100,000) when compared to their corresponding national averages in each country. TB control in border regions is further challenged by limited access to cost-effective tests to diagnose TB and assess drug resistance (DR). We evaluated the performance of a novel, simple and low-cost culture plate technology for isolation and DR testing of Mtb in TB clinics on the Mexican border with Texas.
Methods: We conducted an observational study using sputum from 85 subjects with possible TB identified in TB clinics in Reynosa and Matamoros, Mexico. Their fresh sputa were prospectively digested and decontaminated using standard NaOH-NALC and evaluated for acid-fast bacilli (AFB) in smears or Mtb growth in LJ slants (routine). For the experimental arm we inoculated 1st , 2nd or 3rd generation plates (1, 2 or 3G plates) with thawed leftover sputa already treated with NaOH-NALC or fresh sputa treated with a described mix of salts for digestion and decontamination. The performance of both culture methods was compared for Mtb isolation. The 1G plates were previously validated for assessment of drug resistance, and hence, used here to identify resistance to isoniazid (INH) or rifampicin (RIF).
Results: The plates had a 100% sensitivity and >90% PPV when compared to AFB smears or LJ cultures. Contamination was 1.4% for plates and 12.7% for LJ cultures. Median time-to-positive was 17 days for plates and 63 days for LJ. Resistance per 1G plates was 17.6% to any drug, 14.9% to INH, 9.5% to RIF, and 6.8% to both combined (multi-drug resistant TB).
Conclusions. The plates were as sensitive as reference methods, had less contamination and shorter times for Mtb growth detection. The 1G plate costs less than $5US and provides DR results for three drugs, when compared to local costs of $100 for single RIF-resistance testing with GeneXpert. DR is likely underestimated in the Mexican border clinics where official estimates are ~6% and our findings suggest 3-fold higher rates. Implementation studies for the plates are warranted in Mexican border clinics and other TB endemic regions worldwide where resources are limited.
Academic/Professional Position
Graduate Student
Recommended Citation
Monday, Sean; Ayala, Doris; Aguillón-Durán, Genesis P.; Cruz-Garcia, America; Schami, Alyssa; Hicks, Amberlee; Garcia, Juan Ignacio; Torrelles, Jordi B.; and Restrepo, Blanca I., "Performance of color plates for M. tuberculosis detection and drug resistance screening in Mexican TB clinics across the Texas border" (2024). Research Symposium. 121.
https://scholarworks.utrgv.edu/somrs/2023/posters/121
Included in
Performance of color plates for M. tuberculosis detection and drug resistance screening in Mexican TB clinics across the Texas border
Purpose: Populations along the U.S.-Mexico border have a high prevalence of risk factors for TB such as low socioeconomic status, overcrowding and migration, and consequently, higher TB incidence (up to 12 and 44/100,000) when compared to their corresponding national averages in each country. TB control in border regions is further challenged by limited access to cost-effective tests to diagnose TB and assess drug resistance (DR). We evaluated the performance of a novel, simple and low-cost culture plate technology for isolation and DR testing of Mtb in TB clinics on the Mexican border with Texas.
Methods: We conducted an observational study using sputum from 85 subjects with possible TB identified in TB clinics in Reynosa and Matamoros, Mexico. Their fresh sputa were prospectively digested and decontaminated using standard NaOH-NALC and evaluated for acid-fast bacilli (AFB) in smears or Mtb growth in LJ slants (routine). For the experimental arm we inoculated 1st , 2nd or 3rd generation plates (1, 2 or 3G plates) with thawed leftover sputa already treated with NaOH-NALC or fresh sputa treated with a described mix of salts for digestion and decontamination. The performance of both culture methods was compared for Mtb isolation. The 1G plates were previously validated for assessment of drug resistance, and hence, used here to identify resistance to isoniazid (INH) or rifampicin (RIF).
Results: The plates had a 100% sensitivity and >90% PPV when compared to AFB smears or LJ cultures. Contamination was 1.4% for plates and 12.7% for LJ cultures. Median time-to-positive was 17 days for plates and 63 days for LJ. Resistance per 1G plates was 17.6% to any drug, 14.9% to INH, 9.5% to RIF, and 6.8% to both combined (multi-drug resistant TB).
Conclusions. The plates were as sensitive as reference methods, had less contamination and shorter times for Mtb growth detection. The 1G plate costs less than $5US and provides DR results for three drugs, when compared to local costs of $100 for single RIF-resistance testing with GeneXpert. DR is likely underestimated in the Mexican border clinics where official estimates are ~6% and our findings suggest 3-fold higher rates. Implementation studies for the plates are warranted in Mexican border clinics and other TB endemic regions worldwide where resources are limited.