EVALUATION OF BACTEC MYCO F LYTIC MEDIUM FOR RECOVERY OF MYCOBACTERIAAND FUNGI FROM BLOOD/

The reliability of MYCO/F Lytic medium in the BACTEC 9240 blood cultur e system was evaluated by comparing its performance to that of the Iso lator system for the recovery of fungi and to that of the ESP II syste m for the recovery of mycobacteria. Of 717 specimens of blood cultured for fungi, 24 Here positive; 12 samples were positive with both syste ms, 7 samples were positive with the Isolator system only, and 5 sampl es were positive with MYCO/F Lytic medium only. Fourteen samples grew Histoplasma capsulatum; both systems detected H. capsulatum in seven s amples but the Isolator system alone detected H. capsulatum in seven s amples. The mean times to the detection of H. capsulatum were 8 days ( range, 4 to 13 days) for MYCO/F Lytic medium and 9 days (range, 6 to 1 8 days) for the Isolator system; the mean times to identification were 20 days (range, 15 to 24 days) for isolates recovered with MYCO/F Lyt ic medium and 11 days (range, 6 to 18 days) for those recovered with t he Isolator system (P < 0.05), Cryptococcus neoformans was isolated fr om 10 fungal cultures; five isolates grew in both systems, and five is olates grew in MYCO/F Lytic medium only. The mean times to detection o f C. neoformans were 4 days (range, 2 to 6 days) for MYCO/F Lytic medi um and 7 days (range, 5 to 7 days) for the Isolator system (P < 0.05); the mean times to identification were 15 days (range, 7 to 27 days) f or isolates recovered with MYCO/F Lytic medium and 8 days (range, 7 to 11 days) for those recovered with the Isolator system. Of the 687 sam ples of blood cultured for mycobacteria, 64 blood samples from 42 pati ents grew mycobacteria (58 grew Mycobacterium avium complex, 4 grew My cobacterium kansasii, and 2 grew Mycobacterium tuberculosis); 42 isola tes were recovered with both systems, 18 were isolated with MYCO/F med ium only, and 4 were isolated with the ESP II system only alone (P < 0 .05). The mean time to detection of mycobacteria with MYCO/F Lytic med ium was 14 days, whereas it was 17 days with the ESP II system (P < 0. 05). In summary, the combination of MYCO/F Lytic medium and the BACTEC 9240 instrument is an excellent blood culture system for the growth a nd detection of mycobacteria. A valid assessment of MYCO/F Lytic mediu m with regard to Fungal isolation, however, was not possible due to th e small number of isolates recovered.