Fluoroquinolone resistance in renal isolates of Mycobacterium tuberculosis.

SETTING: 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. DESIGN: 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. CONCLUSION: FQ monotherapy of unsuspected renal TB may delay diagnosis and lead to FQ resistance.

Laboratory diagnosis of mumps in a partially immunized population: The Nova Scotia experience.

BACKGROUND: In 2007, Atlantic Canada experienced a large outbreak of mumps predominately in university students who had received a single dose of measles, mumps and rubella vaccine. The present study describes the performance characteristics of reverse transcriptase polymerase chain reaction (RT-PCR) on buccal and urine specimens and immunoglobulin M (IgM) serology in this partially immune population. METHODS: Patients presenting with symptoms suspicious for mumps had a serum, urine and a buccal swab collected for diagnostic testing. Persons were classified as a 'confirmed' case according to the Public Health Agency of Canada's definition. Sera were tested using an enzyme-linked immunoassay. Detection of mumps virus in buccal swabs and urine samples was performed by RT-PCR. RESULTS: A subset of 155 cases and 376 non-cases that had all three specimens submitted was used for calculating the performance characteristics. The sensitivity of RT-PCR on buccal swabs, urine specimens and IgM serology were 79%, 43% and 25%, respectively. The specificity of RT-PCR on buccal swabs, urine specimens and IgM serology was 99.5%, 100% and 99.7%, respectively. Only 12 of 134 (9%) patients had positive urine specimens in the presence of negative oral swabs. CONCLUSION: RT-PCR on buccal swabs is the ideal specimen for diagnosis. Testing an additional urine sample in an outbreak setting did not increase the diagnostic yield significantly, but doubled testing volume and cost. In addition, the data suggest that, in this partially immune group, IgM serology has little value in the diagnosis of acute infection.

Ovine-associated Q fever.

In Atlantic Canada, the traditional risk factor for acquisition of Q fever infection has been exposure to infected parturient cats or newborn kittens. In this study we describe the first case of Q fever in Nova Scotia acquired as a result of direct exposure to sheep. A serosurvey of the associated flock was undertaken using an indirect immunofluorescence assay (IFA) testing for antibodies to phase I and phase II Coxiella burnetii antigens. This serosurvey revealed that 23 of 46 sheep (50%) were seropositive for the phase II antibody. Four of these sheep had titres of 1:64 including three nursing ewes, one of which had delivered two lambs that died shortly after delivery. Only one ewe had phase I antibodies but had the study's highest phase II antibody titre (1:128). Molecular studies using polymerase chain reaction (PCR) failed to detect C. burnetii DNA in any of the milk specimens.