Hostname: page-component-848d4c4894-nr4z6 Total loading time: 0 Render date: 2024-05-21T16:47:21.383Z Has data issue: false hasContentIssue false
  • English
  • Français

Tuberculosis and Tuberculin Quality: Best Intentions, Misleading Results

Published online by Cambridge University Press:  02 January 2015

M. Sigfrido Rangel-Frausto ,
Samuel Ponce-de-León-Rosales ,
Claudia Martinez-Abaroa  and
Kaare Hasløv
M. Sigfrido Rangel-Frausto
Affiliation:
Division of Hospital Epidemiology, National Institute of Medical Sciences and Nutrition, Mexican Institute for Social Security, Mexico City, Mexico Unit for Hospital Epidemiology Research, Mexican Institute for Social Security, Mexico City, Mexico
Samuel Ponce-de-León-Rosales*
Affiliation:
Division of Hospital Epidemiology, National Institute of Medical Sciences and Nutrition, Mexican Institute for Social Security, Mexico City, Mexico
Claudia Martinez-Abaroa
Affiliation:
Division of Hospital Epidemiology, National Institute of Medical Sciences and Nutrition, Mexican Institute for Social Security, Mexico City, Mexico
Kaare Hasløv
Affiliation:
Analysis and Control Department, Statens Serum Institut, Copenhagen, Denmark
*
Division of Hospital Epidemiology, National Institute of Medical Sciences and Nutrition, Vasco de Quiroga 15, Tlalpan, México, D.F 14000 México
Get access Rights & Permissions [Opens in a new window]

Abstract

Objective:

To compare the performance of three purified protein derivative (PPD) formulations: Tubersol (Connaught); RT23, Statens Serum Institut (SSI); and RT23, Mexico, tested in Mexican populations at low and high risk for tuberculosis (TB).

Design:

A double-blinded clinical trial.

Setting:

A university hospital in Mexico City.

Participants:

The low-risk population was first or second-year medical students with no patient contact; the high-risk population was healthcare workers at a university hospital.

Methods:

Each of the study subjects received the three different PPD preparations. Risk factors for TB, including age, gender, occupation, bacille Calmette-Guerin (BCG) status, and TB exposure, were recorded. A 0.1-mL aliquot of each preparation was injected in the left and right forearms of volunteers using the Mantoux technique. Blind readings were done 48 to 72 hours later. Sensitivity and specificity were calculated at 10 mm of induration using Tubersol as the reference standard. The SSI tested the potency of the different PPD preparations in previously sensitized guinea pigs.

Results:

The low-risk population had a prevalence of positive PPD of 26%. In the low-risk population, RT23 prepared in Mexico, compared to the 5 TU of Tubersol, had a sensitivity of 51%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 86%. The RT23 prepared at the SSI had a sensitivity of 69%, a specificity of 99%, a positive predictive value of 95%, and a negative predictive value of 90%. In the high-risk population, the prevalence of positive PPD was 57%. The RT23 prepared in Mexico had a sensitivity of 33%, a specificity of 100%, and a positive predictive value of 53%; the RT23 prepared at the SSI had a sensitivity of 91%, a specificity of 98%, a positive predictive value of 98%, and a negative predictive value of 89%. RT23 used in Mexico had a potency of only 23% of that of the control. There was no statistical association among those with a positive PPD, irrespective of previous BCG vaccination (relative risk, 0.97; 95% confidence interval, 0.76-1.3; P=.78).

Conclusions:

Healthcare workers had twice the prevalence of positive PPD compared to medical students. RT23 prepared in Mexico had a low sensitivity in both populations compared to 5 TU of Tubersol and RT23 prepared at the SSI. Previous BCG vaccination did not correlate with a positive PPD. Low potency of the RT23 preparation in Mexico was confirmed in guinea pigs. Best intentions in a TB program are not enough if they are not followed by high-quality control.

Type
Original Articles
Information
Infection Control & Hospital Epidemiology , Volume 22 , Issue 8 , August 2001 , pp. 481 - 484
Copyright
Copyright © The Society for Healthcare Epidemiology of America 2001

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1. Guld, J, Bentzon, MW, Bleiker, MA, Griep, WA, Magnusson, M, Waaler, H. Standardization of a new batch of purified tuberculin (PPD) intended for international use. Bulletin of the World Health Organization 1958;19:845–951.Google ScholarPubMed
2. Comstock, GW, Edwards, LB, Philip, RN, Winn, WA. A comparison in the United States of America of two tuberculins, PPD-S and RT23. Bulletin of the World Health Organization 1964;31:161–170.Google Scholar
3. Molina-Gamboa, JD, Ponce-de-Leon-Rosales, S, Rivera-Morales, I, Romero, C, Baez, R, Huertas, M. Evaluation of the sensitivity of RT23 purified protein derivative for determining tuberculin reactivity in a group of health care workers. Clin Infect Dis 1994;19:784–786.CrossRefGoogle Scholar
4. Haslov, K, Closs, O, Moller, S, Bentzon, MW. Studies on the development of tuberculin sensitivity in immunized guinea pigs with demonstration of a close relationship between results of skin tests and the lymphocyte transformation technique. Int Arch Allergy Appl Immunol 1984;73:114–122.CrossRefGoogle ScholarPubMed
5. Bates, JH, Nardell, R. Institutional control measures for tuberculosis in the era of multiple drug resistance: ACP/ATS consensus conference. Chest 1995;108:1690–1710.CrossRefGoogle Scholar
6. Centers for Disease Control and Prevention. Tuberculin skin test survey in a pediatric population with high BCG vaccination coverage—Botswana, 1996. MMWR 1997;46:846–851.Google Scholar