Co-occurrence of amikacin-resistant and -susceptible Mycobacterium tuberculosis isolates in clinical samples from Beijing, China

Received 10 August 2012; returned 4 October 2012; revised 6 February 2013; accepted 11 February 2013Objectives: This study examined the phenomenon of heteroresistance in Mycobacterium tuberculosis clinicalisolates obtained from retreated patients in Beijing, China between 2006 and 2011.Methods: The iPLEX Gold assay platform was used to determine the prevalence of heteroresistance to inject-able second-line drugs (amikacin, kanamycin and capreomycin) in resistant isolates.Results: Heteroresistance was identified in 10.9% of 220 phenotypic amikacin-resistant isolates.Conclusions: Heteroresistance was related mainly to the short duration and repeated use of amikacin andcapreomycin during retreatment. These findings further our understanding of the evolution of resistance to in-jectable drugs used for tuberculosis treatment and help guide the rational use of injectable drugs duringtherapy.Keywords: heteroresistance, MDR-TB, aminoglycoside antibiotics, molecular typing