Prevalences of levofloxacin resistance and pncA mutation in isoniazid-resistant Mycobacterium tuberculosis in Hong Kong.

INTRODUCTION: In 2018, the World Health Organization recommended a 6-month treatment regimen that included levofloxacin and pyrazinamide for isoniazid-resistant Mycobacterium tuberculosis without rifampicin resistance (Hr-TB). Susceptibility testing for both drugs is not routinely performed for Hr-TB in Hong Kong. This study examined the prevalences of levofloxacin and pyrazinamide resistances in Hr-TB and explored associated risk factors. METHODS: All Hr-TB isolates archived during 2018 were retrieved. Isolates were de-duplicated to identify unique cases. Levofloxacin susceptibility testing was performed using the MGIT 960 System; pncA gene sequencing was used as a surrogate indicator of pyrazinamide susceptibility. Previous laboratory records for each case were analysed. RESULTS: In total, 160 phenotypic Hr-TB cases were identified from among 3411 patients with tuberculosis (4.7%). Among these, 157 were analysed, revealing 0.6% (n=1) levofloxacin resistance and 4.5% (n=7) pyrazinamide resistance, respectively. Independent risk factors associated with pncA mutations included history of tuberculosis in the affected patient and isoniazid poly-resistance (ie, double and triple resistances), but not mono-resistance. CONCLUSION: For Hr-TB in Hong Kong, levofloxacin resistance is rare and pyrazinamide resistance-associated pncA mutations are uncommon. Routine susceptibility testing for these drugs is not indicated unless related risk factors are identified.

Molecular detection of Mycoplasma genitalium in endocervical swabs and associated rates of macrolide and fluoroquinolone resistance in Hong Kong.

INTRODUCTION: There is a global trend of increasing macrolide and fluoroquinolone resistance in Mycoplasma genitalium (MG), such that international guidelines recommend molecular detection of resistance if a patient has MG-positive test results. Tests for MG are not routinely performed in Hong Kong. This study examined the detection of MG in endocervical swabs and the associated macrolide and fluoroquinolone resistance rates. METHODS: Endocervical swabs received from two sexual health clinics in Hong Kong for routine assessments of Chlamydia trachomatis and Neisseria gonorrhoeae were also subjected to detection of MG. All MG-positive samples were tested for resistance-mediating mutations in 23S rRNA, parC, and gyrA genes. Laboratory records and past results for each patient were analysed. RESULTS: In total, endocervical swabs from 285 patients were included in this study. Mycoplasma genitalium was detected in swabs from 21 patients (7.4%) by real-time polymerase chain reaction with a commercial kit. Among MG-positive samples which were successfully analysed further, macrolide resistance-mediating mutations in 23S rRNA were found in 42.1% (8/19); fluoroquinolone resistance-related mutations in parC and gyrA were found in 65% (13/20) and 0% (0/20), respectively. All macrolide-resistant MG strains were also fluoroquinolone-resistant (42.1%, 8/19). No assessed factors were associated with the detection of MG or resistance-related mutations. CONCLUSION: In Hong Kong, MG was detected in endocervical swabs from 7.4% of patients in sexual health clinics, with high rates of macrolide and fluoroquinolone resistance. These findings warrant careful review of testing, clinical correlation, and treatment strategies for MG in the context of increasing antibiotic resistance.