Sputum Smears and Cultures for TB

I was asked to provide three sputum samples for cultures, why?

All decisions are made according to the publicly available CDC Tuberculosis Technical Instructions for Panel Physicians. To summarize, applicants are asked to provide sputum smears and cultures on these three occasions:

  1. Applicants who are showing signs or symptoms of TB.
  2. Applicants whose chest x-ray findings are suggestive of tuberculosis disease.
  3. Applicants with known HIV infection.

My doctor says that my chest x-ray is normal, why are you still asking for me to provide sputum smears and cultures?

The chest x-ray findings that the CDC wants to be investigated further with sputum smears and cultures are broader than a typical clinical approach that your doctor may be used to. We have to abide by the rules of CDC.

Between 2016 to 2020, on average, only 2.23% and in 2020 only 1.96% of all Chest X-Rays interpreted at our facilities were found to be requiring sputum smears and cultures. The latest average CDC has reported for the whole world is 4.5%.

Why do I have to provide three samples, why is one not enough?

The number of samples required are defined in the CDC Tuberculosis Technical Instructions for Panel Physicians. According to the instructions three samples must be taken at least 24 hours apart, preferably on consecutive working days, early in the morning.

How much do I have to pay for the sputum smears and cultures?

Duzen Laboratory charges 57$ for the collection, processing and reporting of a single (1) sputum sample, you will have to provide and pay for three (3) samples.

Why is my report valid for only three months?

The duration of validity is defined in the CDC Tuberculosis Technical Instructions for Panel Physicians and is set to three months after the date of last sputum culture is reported.

Why does it take 8 weeks for the results to come in?

The CDC Tuberculosis Technical Instructions for Panel Physicians requires all samples to be cultured for 8 weeks in solid culture and reported.

My medical report expired, do I have to repeat sputum smears and cultures?

Yes. The CDC Tuberculosis Technical Instructions for Panel Physicians requires applicants to repeat the same examination procedure for all expired cases. Unless the chest x-ray findings that initially required you to provide three sputum samples have disappeared we are required to repeat the whole procedure, including the sputum smears and cultures. It is not typical for these signs to disappear.

But I’ve received the bacille Calmette-Guérin (BCG) vaccine before?

According to the CDC Tuberculosis Technical Instructions for Panel Physicians prior receipt of BCG does not change the screening requirements or the required actions based on those results.

But I did an IGRA test and the result is negative?

According to the CDC Tuberculosis Technical Instructions for Panel Physicians IGRA is mainly used for screening applicants between ages 2 through 14 years in countries with an incidence rate of ≥20 cases per 100,000 population and is not a diagnostic test to replace sputum smears and cultures.