Mycobacterial transport medium for routine culture of fine needle aspiration biopsies.

Abstract

Fine needle aspiration biopsy (FNAB) offers a simple outpatient technique for specimen collection in child tuberculosis suspects with peripheral lymphadenopathy. To perform FNAB with mycobacterial culture on an outpatient basis requires use of a sterile transport medium to facilitate bedside inoculation, maintain organism viability and reduce contamination risk en route to the laboratory. The mycobacterial yield and time to positive culture following bedside inoculation into standard mycobacterial growth indicator tubes were compared with initial inoculation into an inexpensive "in-house" liquid growth medium. Of 150 FNAB performed, 57 (38%) cultured Mycobacterium tuberculosis complex. There was one case each with non-tuberculous mycobacteria and Mycobacterium bovis BCG; the remaining 55 being M tuberculosis. Results were concordant in 142 (94.7%) bedside and laboratory inoculation pairs. There was no significant difference in time to positive culture between bedside and laboratory inoculation (16.2 days (SD 0.87) vs 17.1 days (SD 0.85)). Provision of inexpensive specimen transport bottles and practical tuition in FNAB should improve cost-effective diagnosis of tuberculosis at the primary healthcare level.