Repeat positive cultures in Mycobacterium intracellulare lung disease after macrolide therapy represent new infections in patients with nodular bronchiectasis.
The genomic DNA patterns (genotypes) of 55 episodes of late positive sputum isolates, collected after >or=4 consecutive months of negative sputum cultures, in prospective macrolide treatment trials of Mycobacterium avium complex (MAC) lung disease were assessed by pulsed-field gel electrophoresis (PFGE). Having >or=2 cultures positive for MAC after completion of therapy was documented 23 times; of 20 episodes studied by PFGE, 17 (85%) represented new genotypes (i.e., new infections), and 87% occurred in patients with nodular bronchiectasis. With >or=2 positive cultures after therapy was stopped prematurely, 6 (86%) of 7 episodes were relapses. Single positive cultures after completion of therapy occurred 16 times; only 1 (6%) was predictive of a subsequent relapse. No late isolates were macrolide resistant. Thus, relapses of MAC lung disease with these macrolide regimens are unusual, and most infections after completing therapy resulted from new strains in patients with nodular bronchiectasis.
Department of Microbiology, University of Texas Health Center at Tyler, Tyler, TX 75708, USA. richard.wallace@uthct.edu
Richard J
RJ
Wallace
Yansheng
Y
Zhang
Barbara A
BA
Brown-Elliott
Mitchell A
MA
Yakrus
Rebecca W
RW
Wilson
Linda
L
Mann
Leslie
L
Couch
William M
WM
Girard
David E
DE
Griffith
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D017963:Azithromycin / Q000008:administration & dosage / Q000627:therapeutic use*; D001987:Bronchiectasis / Q000150:complications*; D017291:Clarithromycin / Q000008:administration & dosage / Q000627:therapeutic use*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D006801:Humans; D008171:Lung Diseases / Q000150:complications / Q000188:drug therapy* / Q000382:microbiology*; D008297:Male; D008875:Middle Aged; D015269:Mycobacterium avium Complex / Q000235:genetics / Q000302:isolation & purification*; D015270:Mycobacterium avium-intracellulare Infection / Q000150:complications / Q000188:drug therapy*; D016133:Polymerase Chain Reaction; D011446:Prospective Studies; D013183:Sputum / Q000382:microbiology
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D017963:Azithromycin; D017291:Clarithromycin