Fluoroquinolone resistance in renal isolates of Mycobacterium tuberculosis.
METHODS
Alberta, Canada, 1990-2003.


OBJECTIVE
Monotherapy of active tuberculosis (TB) promotes drug resistance. Given the common practice of empiric fluoroquinolone (FQ) therapy for urinary tract infections (UTI) and frequent delayed diagnosis of renal TB, we assessed urine Mycobacterium tuberculosis isolates for FQ resistance.


METHODS
Retrospective study. Urine M. tuberculosis isolates underwent FQ susceptibility testing. Records were reviewed for evidence of FQ exposure and diagnostic delay.


RESULTS
Among 78 culture-positive renal TB patients between 1990 and 2003, initial isolates of M. tuberculosis were available from 74 (94.9%). Three (4.1%) were FQ-resistant. Previous FQ use was confirmed in nine cases (12.2%). FQ-exposed isolates were more likely than non-exposed isolates to be FQ-resistant (2/9, 22.2% vs. 1/65, 1.5%, P = 0.037). Among 41 cases (55.4%) with signs or symptoms of UTI, eight (19.5%) had previous FQ exposure, of which seven (87.5%) had delayed diagnosis. Only 15/33 (45.5%) UTI symptomatic cases without prior FQ exposure had delayed diagnosis (P = 0.050). In 2/8 (25%) UTI symptomatic cases with prior FQ exposure, the M. tuberculosis isolate was FQ-resistant.


CONCLUSIONS
FQ monotherapy of unsuspected renal TB may delay diagnosis and lead to FQ resistance.
Webster
D
D
Department of Internal Medicine, Saint John Regional Hospital, Saint John, New Brunswick, Canada. dvwebste@dal.ca
Long
R
R
Shandro
C
C
Pettipas
J
J
Leblanc
J
J
Davidson
R
R
Fanning
A
A
D000328:Adult; D000368:Aged; D000416:Alberta; D000995:Antitubercular Agents / Q000494:pharmacology; D057210:Delayed Diagnosis; D024881:Drug Resistance, Bacterial; D005260:Female; D024841:Fluoroquinolones / Q000494:pharmacology*; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000302:isolation & purification; D012189:Retrospective Studies; D014398:Tuberculosis, Renal / Q000175:diagnosis / Q000188:drug therapy / Q000382:microbiology*; D014552:Urinary Tract Infections / Q000175:diagnosis / Q000188:drug therapy / Q000382:microbiology
D000995:Antitubercular Agents; D024841:Fluoroquinolones