Increase in Multidrug Resistant FC428-Like Isolates Harboring the Mosaic penA 60.001 Gene, in Nanjing, China (2017-2020).

BACKGROUND

Since the first Chinese report of the ceftriaxone-resistant FC428 clone in 2016, additional FC428-like, 60.001 isolates have been identified in China.

OBJECTIVE

To document the rise in 60.001 isolates in Nanjing, China, and characterize their molecular and epidemiological features.

METHODS

minimum inhibitory concentrations (MICs, mg/L) for ceftriaxone, cefixime, penicillin, tetracycline, ciprofloxacin, azithromycin, spectinomycin, gentamicin and zoliflodacin were determined by agar dilution. MICs for ertapenem were measured by E-test. N. antimicrobial sequence typing (NG-STAR) of seven loci ( and ) was analyzed together with multiantigen sequence typing (NG-MAST) and multilocus sequence typing (MLST). Phylogenetic analysis was also performed using whole genomic sequencing (WGS).

RESULTS

Fourteen FC428-related 60.001 infections were identified out of 677 infections from 2017 to 2020, in Nanjing, representing an incremental yearly rise in the percentage of the city's isolates that were FC428-related. Seven FC428-related N. infections were acquired in Nanjing, proper; four others in eastern Chinese cities and three from unknown locations. All FC428-related isolates were resistant to ceftriaxone, cefixime, ciprofloxacin, tetracycline and penicillin but susceptible to spectinomycin, gentamicin, ertapenem and zoliflodacin; three strains were resistant to azithromycin. 60.001 isolates displayed closely related MLST types and NG-STAR types but relatively distant NG-MAST types. WGS showed a phylogenetic analysis that intermingled with other international isolates.

CONCLUSION

60.001 isolates emerged in Nanjing, China, beginning in 2017, and have continued to rise.