Module 9 Recording and reporting culture results

1. Module 9Recording and reporting culture results

2. Learning objectives At the end of this module you will be able to: • use the culture quantification scheme. • describe the time-frame for reporting results. • record culture identification results in the laboratory register. • use the WHO form for a preliminary report of culture. • report a M. tuberculosis complex culture on WHO form.

3. Content outline • Culture semiquantitative reporting • Detection of false-positive cultures • The laboratory register for culture (DST) • WHO report form for culture • preliminary report • final report

4. Laboratory culture (DST) register PATIENT • Patient’s name /Lab serial number • New/retreatment / follow-up (months) SPECIMEN • Centre of origin / Local lab ID number • Date collected/received / Type of specimen AFB smear • Local result / culture lab result CULTURE logbook • Media / date of inoculation • Growth record (weekly) • AFB morphology • Date of report

5. Laboratory culture (DST) register ../.. ../..

6. Culture semiquantitative reporting

7. Laboratory register • Note results immediately. • Always check agreement between number on tube and number in laboratory register. • Use a red pen for positive results. • Check for clerical errors!

8. Interpretation of culture results:possible false-positive cultures due to cross-contamination Suspect cross-contamination when: • there is only one positive culture among several samples; • a culture turns positive after prolonged incubation; • colony count on solid medium is low (1–5 colonies). Check whether the specimen was processed after one that was highly positive.

9. Preliminary report • Date of receipt of specimen/Lab serial number • AFB results (method) • Culture semiquantitative reporting method • Date of report / Signature

10. Laboratory culture (DST) register DST and identification register • DST serial number • Primary culture serial number • Date culture positive • Date DST inoculation DST logbook • Controls /Drugs • Identification tests Final results • Identification • Resistance profile • Date of report

11. Laboratory culture (DST) register ../.. ../.. 11

12. WHO form – final report • Reference lab numbers • Microscopy results (indication of method) • Culture growth results • Identification of M. tuberculosis complex • DST results • Date of reporting • Signature

13. WHO form – final report

14. Reporting time-frame • Contaminated culture: as soon as it is identified • M. tuberculosis: as soon as it is identified • Negative (at 6 weeks for liquid culture) • Negative (at 8 weeks)

15. Quality assurance • Always check agreement between the laboratory register number and the number written on tubes/slants. • Use WHO forms for reporting results. • A copy of the completed final report should be retained in the laboratory for 2 years. • 80% of the results are reported within 42 days. • Positive cultures are reported within 48 hours of growth detection.

16. True and false exercise • Early positive culture (less than 7 days) increases the suspicion of TB. • TB colonies become clearly visible after at least 2 weeks (on solid media). • A preliminary report should be made available to the clinician as soon as there is presumptive identification.

17. Module review: take-home messages • Positive cultures should be reported to the clinician immediately, using a semiquantitative scale. • The laboratory register and the report should be completed carefully. • Keep in mind the possibility of a laboratory cross-contamination in selected cases.

18. Self-assessment • Explain the schedule for reporting culture results. • Why is semiquantitative reporting needed? • What information should a final report include?