Latent tuberculous infection prevalence among paediatric contacts of drug-resistant and drug-susceptible cases.

SETTING

Tuberculosis (TB) clinic in Tijuana, México.

BACKGROUND

Tuberculin conversion rates in contacts of drug-resistant cases have been reported to be lower than among contacts of drug-susceptible cases.

OBJECTIVE

To determine if the prevalence of latent tuberculous infection (LTBI) among paediatric contacts of drug-resistant cases is lower than that of contacts of drug-susceptible cases.

DESIGN

In a cross-sectional study, LTBI among paediatric contacts of culture-proven TB cases was evaluated using the tuberculin skin test and interferon-gamma release assay. Rates among contacts of drug-susceptible and drug-resistant cases were compared.

RESULTS

The TST was positive in 83.1% of the drug-susceptible group vs. 76.0% for the drug-resistant group (P = 0.25). Using the QuantiFERON Gold In-Tube (QFT-GIT) assay, drug-resistant cases had a higher rate of positivity than the drug-susceptible group, although this difference did not reach statistical significance (42.3% positivity among drug-susceptible cases vs. 57.7% among drug-resistant cases; P = 0.48).

CONCLUSIONS

The proportion of LTBI is similar among paediatric contacts, regardless of whether the index case is drug-resistant or -susceptible.