Evaluation of the sensitivity of RT-23 purified protein derivative for determining tuberculin reactivity in a group of health care workers.
Since 1958 the World Health Organization (WHO) has recommended the use of RT-23 (2 tuberculin unit [TU] purified protein derivative [PPD]) instead of the standard 5 TU PPD to establish the prevalence of tuberculosis (TB) around the world. Before starting a hospital program to control the transmission of TB among health care workers at the National Institute of Nutrition (Mexico City), we compared the tuberculin product commonly used in Mexico (RT-23) with that used in the United States (5 TU PPD). In this trial the Mantoux test was performed on 80 health care workers from various areas of the hospital: 5 TU PPD and RT-23 were simultaneously inoculated in the left forearm and in the right forearm, respectively. The test results for both tuberculin products were read 72 hours later. When a 10-mm induration was used as the cutoff for reactivity, the specificity with use of RT-23 was 100%, but the sensitivity was only 57%. However, when a 5-mm induration was used as the cutoff, the sensitivity with use of RT-23 was 90%. Because of these findings, we advise that every country using RT-23 either consider changing the cutoff for reactivity or consider using 5 TU PPD for reassessment of the data on the incidence and prevalence of TB that were obtained with use of RT-23 (the product recommended by WHO).
Molina-Gamboa
J D
JD
Department of Infectious Diseases, National Institute of Nutrition "Salvador Zubirán," Mexico City, Mexico.
Ponce-de-León-Rosales
S
S
Rivera-Morales
I
I
Romero
C
C
Báez
R
R
Huertas
M
M
Osornio
G
G
D000328:Adult; D000368:Aged; D005260:Female; D006282:Health Personnel; D006801:Humans; D017053:Infection Control; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D014373:Tuberculin; D014374:Tuberculin Test; D014376:Tuberculosis / Q000517:prevention & control
D014373:Tuberculin