Microbiologic evaluation of the patient’s TB organism is very important. However, it must be emphasized to all parties that the lack of microbiologic proof of TB in a child never rules out disease. Once the clinical diagnosis of TB in a child is made and treatment is begun, the treatment course should be completed unless a strong alternate diagnosis for the disease process is made. Only positive results are helpful.
- Negative cultures do not rule out TB
- Treatment for active TB should be initiated immediately. Treatment should not be delayed while waiting for smear and culture results
- The first specimen collected is most likely to yield a positive culture
- Because there are very few organisms in the specimens, gastric aspirates rarely are smear positive (very young babies sometimes have smear positive gastric aspirates)
- Historically, three gastric aspirates from a child with TB has a 40% yield
- Young babies have the very highest culture yield (nearly 100% yield for < 3 month old infant)
The most important elements for successful gastric aspirate collection are:
- The child should be restrained well
- The child needs to be strictly NPO
- Use a 10 French or larger tube
- Puff in the child’s face as the tube enters the child's throat to elicit swallowing
- Use water not saline for irrigation if necessary and neutralize the specimen promptly