C2-1984. Real-Time PCR for Fluoroquinolone Resistance Detection of Mycobacterium tuberculosis Isolated from HIV-Associated Tuberculous Meningitis Patients
Session: Poster Session: Resistance in Mycobacteria
Monday, October 27, 2008: 12:00 AM
Room: Hall C
Background: Fluoroquinolone (FQN) resistance in Mycobacterium tuberculosis (M.tb) is a global concern; the prevalence rate in Vietnam is unknown. This study used Real-time PCR (RT-PCR) to detect FQN resistance in M.tb isolates from patients with HIV-associated Tuberculous Meningitis (TBM). These patients are more likely to have multidrug resistant (MDR) TBM which has extremely high mortality. FQNs probably represent the most effective drugs for treatment of MDR TBM. Methods: Isolates from 171 HIV-associated TBM patients who enrolled in three consecutive clinical studies at Pham Ngoc Thach Hospital and the Hospital for Tropical Diseases, HCMC, Vietnam, from 2000 to 2007, were tested by RT-PCR assay for gyrA mutations. In this assay, three Locked Nucleic Acid probes were used to detect the three most common mutations, A90V, S91P and D94X, in the Quinolone Resistance Determining Region of gyrA (previously published method (Doorn et al, 2008)).
Mutants were confirmed by sequencing and phenotypic Drug Susceptibility Testing (DST) for ofloxacin at 2 µg/ml.
All isolates were spoligotyped. Results: Sensitivity and specificity of RT-PCR are 91.5% and 100% against gyrA sequencing. The RT-PCR assay detected mutations in 3.5% (6/171) of HIV-associated TBM patients. 8% (14/171) isolates were MDR by standard DST testing for first-line drugs. 58% (100/171) isolates were Beijing genotype. Conclusions: Although relatively rare among these patients, FQN resistance is a cause for grave concern because FQNs are likely to be the most effective treatment option for MDR TBM. This RT-PCR is an accurate rapid technique to screen for FQN resistant M.tb.
D. HOA1, D Thu2, Duong Duy An3, G. Thwaites2, J Farrar2, M CAWS2, M. Torok2, N Chinh4, N. Bang1, N. Chau4, N. Lan1, N. Dung1, R. Doorn2, T Chau4 and  D. Duy An, None., (1)Pham Ngoc Thach Hospital, (2)Oxford University Clinical Research Unit, (3)Oxford University Clinical Research Unit, Ho Chi Minh, Viet Nam, (4)Hospital for Tropical Diseases


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