Primary drug and multidrug resistant tuberculosis, of the diagnostic properties of the sputum smear versus culture method for tuberculosis diagnosis in an Ecuadorian urban public health facility
Background: The accurate diagnosis and effective prevention and control of tuberculosis (TB) are major global public health challenges. Ecuador has among the highest documented TB incidence (59/100,000 inhabitants) and mortality rates in the Americas region (27/100,000 inhabitants). In addition, TB multi-drug resistance is becoming increasingly common. The culture method is the preferred method of choice for diagnosing TB in the United States and many other high resource countries due to its high documented sensitivity. An added benefit of the methods is that it also can be used to detect primary TB resistance. In contrast, despite its lower diagnostic sensitivity, the sputum smear method is most often used in low resource countries with a high disease burden, including Ecuador. The main reason for this is due to its lower cost, quick turnaround time and reduced technology requirements. However, scarce data have been published comparing the diagnostic properties of the two methods in a high-volume public health care setting such as in Ecuador or other low resource neighboring countries. Methods: The major objective of the cross-sectional study was to compare the diagnostic properties of the sputum smear with the culture method with respect to sensitivity, specificity, and predictive value. Another objective was to reveal the prevalence of drug-resistance. The data were collected from a consecutive sample of 1487 suspected TB cases referred during a 12-month period (1999–2000) by public health care professionals to the Instituto Nacional de Higiene "Leopoldo Izquieta Perez" National Laboratory in Quito, Ecuador. Results: The study displays a low sensitivity (58%) while the specificity was high (97.8%). Of 10% of the sample size, 32% exhibited drug resistance (9% single drug, 23% multi-drug) and 4 cases of complete resistance. Conclusion: The findings suggest there is a low sensitivity when using sputum smear as the standard diagnostic exam. In describing the drug-resistance in the sample, it was found that Isoniazid was the drug that showed the most resistance (3.8%). In multi-drug resistance, Isoniazid with Rifampicin had the most reported drug resistance (7.9%). This means that high levels of isoniazid and rifampicin resistance show that some of these patients used these drugs to treat a non-tuberculosis infection. Recommendations are to use culture as a standardized test in unison with sputum smear, and to create an intensive monitoring program of treatment and surveillance for tuberculosis and tuberculosis resistance.
Groeschel, Sandra Luz, "Primary drug and multidrug resistant tuberculosis, of the diagnostic properties of the sputum smear versus culture method for tuberculosis diagnosis in an Ecuadorian urban public health facility" (2013). ETD Collection for University of Texas, El Paso. AAI1552335.