Ursula received 6 months of rifampin, pyrazinamide and ethambutol and her radiograph improved markedly. After completion of therapy, radiographs taken 4 and 12 months afterwards continued to improve. The results of Ursula's gastric aspirate allowed for short and efficient therapy with the best drug regimen. If we had not known that Ursula's isolate was INH resistant (unlike her mother's), her therapy may have been complicated by radiographic and clinical worsening, requiring therapy changes and reevaluation.
Teaching points:
- Exemplify the utility of gastric aspirate collection
- Determine when to use the gastric aspirate procedure
- Review pediatric TB diagnosis and treatment
Results of mycobacterial cultures from gastric aspirate collection are very valuable. A positive culture is comforting to the parents and health care providers that the correct diagnosis has been made and the child is being correctly treated. This is particularly valuable when the patient's radiograph is slow to improve. Susceptibility information allows for the most accurate, brief and non-toxic treatment regimen to be used.
Gastric aspirates should be collected from young children with suspected pulmonary tuberculosis. Collection can be deferred when the child has a very close contact with active tuberculosis from whom susceptibility information will be available very soon. If there is any possibility that there is another source case in the child's environment or that the presumed source case' culture material will not result in a positive culture and susceptibility information, the child should undergo gastric aspirate collection. Gastric aspirate sampling is recommended in cases of suspected disseminated TB or meningeal TB.
Most children suspected of having active tuberculosis should be treated with 4 drug TB therapy by directly observed therapy immediately after culture collection. Treatment should never be delayed pending smear or culture results (smears are almost never positive from gastric aspirate specimens). Three drug treatment should be used for patients whose source case is known to have pan-susceptible TB or who live in areas of VERY low resistance with no exposure risks for resistant TB. Ethambutol can be discontinued once the source case or child has been found to have drug susceptible TB.
Two months into treatment, a repeat radiograph should be obtained. If the child has received and retained their TB drug doses consistently, there is no concern that the child or source has drug-resistant TB and the child is clinically improved on treatment, the regimen can be trimmed to INH and rifampin twice weekly by DOT for four more months. The duration of therapy is measured by number of DOT doses received, rather than calendar months. At 6 months into therapy, the radiograph should be repeated. If significantly better and no clinical or microbiologic concerns, the therapy can be stopped and the child should be watched for the next year for evidence of recurrence.
If the child or source case isolate is resistant to INH, the child should be treated with rifampin, pyrazinamide and ethambutol for at least 6 months with similar radiographic monitoring.
If the child has TB resistant to rifampin or more than one drug, close and ongoing consultation with a pediatric TB expert is strongly advised.