MTD TEST

Description of Event or Problem

THREE HIV-INFECTED PTS SEEN IN RPTR'S INSTITUTION WITH ABNORMAL CHEST RADIOGRAPHS AND FLUOROCHROME STAIN-POSITVE SPUTUM WERE EVALUATED FOR TUBERCULOSIS, INCLUDING PERFORMANCE OF THE TEST ON EXPECTORATED SPUTUM SAMPLES. TWO OF THREE PTS' SPUTA WERE HIGHLY SMEAR-POSITIVE (I.E. >100 BACILLI/HIGH POWER FIELD), WHILE THE THIRD PT'S SPUTUM CONTAINED 6-10 BACILLI/HPF. RESULTS ON THE INITIAL SPECIMENS FROM THESE PTS RANGED FROM 43,498 TO 193,858 RLU. MFR DEFINES VALUES >_ 30,000 RLU AS INDICATIVE OF POSITIVE TEST, I.E., THE PRESENCE OF M. TUBERCULOSIS RNA. ALL THREE PTS' SPUTUM CULTURES YIELDED GROWTH OF M. KANSASII WITHIN 6-12 DAYS. ONE PT'S CULTURE ALSO CONTAINED M. AVIUM, BUT NONE OF THE INITIAL OR FOLLOW-UP CULTURES FROM THE PTS REVEALED M. TUBERCULOSIS. HOWEVER, SUBSEQUENT CULTURES FROM ALL THREE PTS AGAIN REVEALED M. KANSASII. OTHER SPUTUM SPECIMENS FROM TWO OF THE PTS THAT HAD ONLY 1+ OR 2+ SMEAR POSITIVITY WERE TEST-NEGATIVE IN 2/3 INSTANCES. A FOURTH PT WITH 1+ SMEAR POSITIVE SPUTUM DUE TO M. KANSASII YIELDED A NEGATIVE TEST. FIVE CULTURES OF M. KANSASII (INCLUDING THESE 4 PTS' ISOLATE AND CULTURES OF SEVERAL OTHER SPECIES WERE EXAMINED AT DENSITIES OF TEST. ALL FIVE ISOLATES OF M. KANSASII AND 3/3 ISOLATES OF M. SIMIAE YIELDED FALSE-POSITIVE TESTS WITH RLU VALUES OF 75,191 TO 335,591. THESE RESULTS INDICATE THAT LOW-LEVEL FALSE-POSITIVE RESULTS CAN OCCUR DUE TO M. KANSASII AND POSSIBLY OTHER MYCOBACTERIUM SPECIES IN SPUTUM. RLU VALUES OF 30,000-400,000 SHOULD BE INTERPRETED WITH CAUTION. ADD'L PTS'S AGES: 40, 44. ADD'L DATES OF EVENT: 4/4/96, 4/5/96.