Evaluation of Neisseria gonorrhoeae Isolates Susceptibility to Tetracycline Antibiotics from 9 Provinces in China Since 2020

Abstract

Purpose The increasing drug resistance of Neisseria gonorrhoeae has become a serious public health concern. This study investigated N. gonorrhoeae isolates susceptibility to tetracycline antibiotics and the correlation between minimum inhibitory concentrations (MICs) of different antibiotics. The presence of resistance determinants in N. gonorrhoeae strains displaying different levels of tigecycline resistance was also compared. Methods The minimum inhibitory concentrations (MICs) of tetracycline, minocycline, tigecycline, eravacycline, omadacycline on 412 N. gonorrhoeae isolates were measured by the agar dilution method. The MICs of ceftriaxone and azithromycin were also measured to determine the correlations between antibiotics by the value of the correlation coefficient R . The presence of resistance determinants was identified through polymerase chain reaction (PCR) and sequencing. Results The MIC 90 was 64mg/L for tetracycline, 64mg/L for minocycline, 0.5mg/L for tigecycline, 0.5mg/L for eravacycline, 4mg/L for omadacycline, 0.25 mg/L for ceftriaxone, and 1mg/L for azithromycin. The MIC 90 and mode of tigecycline and eravacycline were much lower than those of tetracycline and minocycline. A poor correlation between omadacycline, eravacycline and tetracycline susceptibility was observed. Minocycline has a strong correlation with tetracycline. PorB1 typing, TetM -encoding plasmid, and mtrR promoter adenine deletion were significantly correlated with tigecycline MIC > 0.25mg/L. Conclusion This study suggested that tigecycline and eravacycline had better in vitro activity and might be alternative antibiotics against resistant N. gonorrhoeae infections. Nevertheless, further in vitro experiments and clinical studies are needed for verification.

Alternatives Therapeutic Approaches to Conventional Antibiotics: Advantages, Limitations and Potential Application in Medicine

“…Moreover, eravacycline has demonstrated low MIC50 levels against some clinically significant anaerobic bacteria, including Bacteroides fragilis , Clostridium difficile , and Clostridium perfringens [ 33 , 35 , 36 ]. For Neisseria gonorrhoeae the MIC eravacycline was 0.12 μg/mL and MIC90 was 0.25 μg/mL, compared with 0.25 and 0.5 μg/mL, respectively, for tigecycline; no breakpoint has been defined for either agent [ 37 ]. Among isolates with reduced susceptibility to ceftriaxone or cefixime, 95% had an MIC that remained ≤0.25 μg/mL for eravacycline and ≤0.5 μg/mL for tigecycline.…”