Am. J. Respir. Crit. Care Med., Vol 155, No. 1, 01 1997, 81-86.
Two-step tuberculin skin testing in HIV-infected persons in Uganda
MT Hecker, JL Johnson, CC Whalen, S Nyole, RD Mugerwa and JJ Ellner
Department of Medicine, Case Western Reserve University and University Hospitals of Cleveland, Ohio 44106-4984, USA.
Identifying persons infected with both human immunodeficiency virus (HIV)
and Mycobacterium tuberculosis (MTB) is often difficult because of the
reduced sensitivity of tuberculin skin testing in HIV-infected persons. To
determine the value of two-step tuberculin skin testing (TTST) as a method
of increasing the sensitivity of tuberculin skin testing in HIV-infected
persons, a consecutive sample of 58 HIV- infected persons being screened
for a TB preventive therapy trial in Uganda with an initial purified
protein derivative (PPD) response < 5 mm completed two-step tuberculin
and candida skin testing. The mean change in PPD size between the two
tests, placed a mean of 8 d apart, was +2.1 mm (SD 4.4 mm, range -4 to +16
mm). Seventeen subjects (29%) had a boosted response (PPD1 < 5 and PPD2
> or = 5). In a multiple logistic regression model, boosted responses
were independently associated with a CD4 count between 200 and 500
microl(-1) (p = 0.02) and a higher body mass index (p = 0.05). TTST may be
valuable in identifying MTB infection and in preventing misclassification
of boosted responses as skin test conversions in HIV-infected persons,
especially persons with CD4 counts between 200 and 500 microl(-1) from
areas with a high prevalence of MTB infection or from areas with a low
prevalence of MTB infection who have other risk factors for MTB infection.
