Siyuan He,1,2,* Yuzhen Zou,1,2,* Mengling Zhan,1,2,* Qi Guo,1,2 Yongjie Zhang,1,2 Zhemin Zhang,1 Bing Li,1 Shaoyan Zhang,1 Haiqing Chu1,3 1Department of Respiratory Medicine, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai 200433, People’s Republic of China; 2Tongji University School of Medicine, Shanghai 200092, People’s Republic of China; 3Shanghai Key Laboratory of Tuberculosis, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai 200433, People’s Republic of China*These authors contributed equally to this workCorrespondence: Haiqing Chu; Shaoyan ZhangDepartment of Respiratory Medicine, Shanghai Pulmonary Hospital, Tongji University School of Medicine, No. 507 Zhengmin Road, Shanghai 200433, People’s Republic of ChinaTel/ Fax +86 21 6511 5006Email chu_haiqing@126.com; zhangshaoyan000@163.comPurpose: Imipenem is one of the very few effective options for treating Mycobacterium abscessus (M. abscessus) infections; the development of imipenem resistance is a major health concern.Materials and Methods: The susceptibility of 194 clinical M. abscessus isolates to imipenem was determined. The ability of imipenem to synergize with N,N,N′,N′-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN), a zinc chelator and a metallo-β-lactamases (MBLs) inhibitor, to inhibit M. abscessus growth was also assessed.Results: M. abscessus exhibited an elevated resistance to imipenem (MIC50 = 16 mg/L, MIC90 = 64 mg/L). A combination of TPEN and imipenem synergized to inhibit the growth of 100% of imipenem-resistant and 79.2% of imipenem-resistance intermediate isolates; no synergy was observed treating imipenem-sensitive isolates. A remarkable decrease in the MIC50 (from 16 to 4 mg/L) and MIC90 (from 64 to 8 mg/L) of imipenem was observed when it was combined with TPEN; the portion of imipenem-resistant isolates also decreased (from 48.4% to 0%). Consistent with these results demonstrating synergy, a time-kill assay showed the addition of TPEN significantly improved the bactericidal activity of imipenem toward M. abscessus. Similarly, EDTA (a potent MBLs inhibitor) promoted the anti-M. abscessus activity of imipenem in a disk assay, corroborating the effect of TPEN and supporting the role of MBLs in imipenem resistance exhibited by some isolates.Conclusion: These findings demonstrate that TPEN can reduce the resistance of M. abscessus to imipenem and suggest that the inhibition of MBLs activity is the underlying mechanism.Keywords: Mycobacterium abscessus, TPEN, imipenem resistance, metallo-β-lactamases
