Mycobacterium, Rapid Grower, Susceptibility Test
For mycobacteria isolated in CTBL or in other laboratories
Isolates identified in referring labs must specify the organism’s identification and clinical source on the lab request form. For further instructions on packing, refer under IDENTIFICATION OF MYCOBACTERIA.
Susceptible, Intermediate, Resistant, according to CLSI interpretive criteria
1 - 2 weeks
Once a week
Drugs tested: Amikacin, cefoxitin, ciprofloxacin, clarithromycin*, doxycycline, imipenem**, linezolid, tobramycin***, trimethoprim-sulfamethoxazole and moxifloxacin. Tigecycline MICs are provided only upon request as there are no interpretative guidelines. *Class representative for newer macrolides e.g. azithromycin. For the detection of the erm gene which causes inducible resistance to macrolides, a preliminary result is issued if the isolate is susceptible after Day 5 of incubation, followed by a final result after Day 14.
Identification of M. abscessus to the subspecies level (M. abscessus subsp abscessus, M. abscessus subsp massiliense, and M. abscessus subsp bolletti) is advised as the resistance mechanisms and profiles may vary according to the subspecies. The Hain NTM-DR identification test is chargeable and must requested by the ordering clinician.
** Not predictive of results for meropenem or ertapenem as the activity against rapidly growing mycobacteria is greater for imipenem than for meropenem or ertapenem. ***M. chelonae from eye cultures only.