Comparative tuberculin reactivity to two protein derivatives

Area of Science:

• Medical Microbiology
• Epidemiology
• Public Health

Background:

• Tuberculosis remains a global health concern, necessitating accurate diagnostic tools.
• Understanding tuberculin reactivity in healthcare professionals is crucial for infection control.
• Evaluating new tuberculin reagents ensures diagnostic efficacy and accessibility.

Purpose of the Study:

• To assess tuberculin reactivity in medical students.
• To determine the diagnostic utility of RT-23 purified protein derivative (PPD) manufactured in Mexico.
• To compare RT-23 PPD with a standard American PPD product.

Main Methods:

• A blind, comparative study involving 98 medical students (69 first-year, 29 fifth-year).
• Simultaneous administration of RT-23 (2 TU PPD) and American PPD (5 TU PPD) to separate forearms.
• Tuberculin reactions were read 48 hours post-administration, with induration >= 10 mm considered positive.

Main Results:

• Positive tuberculin reactivity was higher in fifth-year students (41%) compared to first-year students (16%) using 5 TU PPD.
• RT-23 PPD exhibited 87% sensitivity and 92% specificity.
• A significant difference in positivity between fifth and first-year students (P = 0.014) indicated an estimated annual conversion rate of 5.1%.

Conclusions:

• RT-23 PPD is a viable alternative to the American 5 TU PPD, showing comparable utility in this medical student population.
• The high annual tuberculosis conversion rate among medical students underscores the need for robust preventive and early diagnosis programs.
• Continued monitoring of tuberculin reactivity in healthcare workers is essential for tuberculosis control efforts.