Impact of the gonococcal FC428 penA allele 60.001 on ceftriaxone resistance and biological fitness

Abstract

Global dissemination of the Neisseria gonorrhoeae ceftriaxone-resistant FC428 clone jeopardizes the currently recommended ceftriaxone-based first-line therapies. Ceftriaxone resistance in the FC428 clone has been associated with the presence of its mosaic penA allele 60.001. Here we investigated the contribution penA allele 60.001 to ceftriaxone resistance and its impact on biological fitness. Gonococcal isolates expressing penA allele 60.001 and mosaic penA allele 10.001, which is widespread in the Asia-Pacific region and associated with reduced susceptibility to ceftriaxone and cefixime, were genetic engineered to exchange their penA alleles. Subsequent antimicrobial susceptibility analyses showed that mutants containing penA 60.001 displayed 8-to 16-fold higher ceftriaxone and cefixime minimal inhibitory concentrations (MICs) compared with otherwise isogenic mutants containing penA 10.001. Further analysis of biological fitness showed that in vitro liquid growth of single strains and in the competition was identical between the isogenic penA allele exchange mutants. However, in the presence of high concentrations of palmitic acid or lithocholic acid, the penA 60.001-containing mutants grew better than the isogenic penA 10.001containing mutants when grown as single strains. In contrast, the penA 10.001 mutants outcompeted the penA 60.001 mutants when grown in competition at slightly lower palmitic acid or lithocholic acid concentrations. Finally, the penA 60.001 mutants were outcompeted by their penA 10.001 counterparts for in vivo colonization and survival in a mouse vaginal tract infection model. In conclusion, penA allele 60.001 is essential for ceftriaxone resistance of the FC428 clone, while its impact on biological fitness is dependent on the specific growth conditions.

Ceftriaxone-resistant, multidrug-resistant Neisseria gonorrhoeae with a novel mosaic penA-237.001 gene, France, June 2022

“…Furthermore, the high-level ceftriaxoneresistant F89 isolate, which emerged in this genomic background, was reported only in France and Spain [14] and its spread was likely limited by a decreased biofitness [18]. The ceftriaxone-resistant F90 and F91 isolates, associated with the internationally spreading FC428 clone containing penA-60 [5,[7][8][9][10][11][12], appeared in France in 2017 and 2019, respectively [5,7]. Notably, the patient with F91 was infected by her husband, who acquired the infection from a sex worker in Cambodia.…”

“…Resistance to ESCs was conferred by the novel mosaic penA allele designated as penA-237.001, encoding an amino acid sequence 99.1% identical (i.e. five substitutions: P328A, A480P, S483T, I485T and T534A; nucleotide identity: 98.7%) to that encoded by penA-60.001, which causes ESC resistance in the internationally spreading FC428 clone [5,[7][8][9][10][11][12]. The penA-237.001 encodes a mosaic penicillin-binding protein 2 (PBP2) including the amino acid substitutions A311V, I312M, V316T and G545S associated with ESC resistance [13].…”

“…Phylogenomic comparison to other gonococcal genomes (n = 36,310) showed that F92 belonged to the genomic sublineage A2, where ceftriaxone-resistant isolates have been previously identified. However, the ceftriaxone-resistant MDR F92 isolate was very distant from the internationally spreading FC428 clone [8][9][10][11][12][13] (Figure 1). F92 instead clustered with several of the mostly recently detected Asian MLST ST1901 and ST1579 isolates (Figure 2); the three most similar isolates (MLST ST1901) differed by 1,381-1,392 SNPs.…”

Emergence and Genomic Characterization of Neisseria gonorrhoeae Isolates with High Levels of Ceftriaxone and Azithromycin Resistance in Guangdong, China, from 2016 to 2019

“…These results illustrated that the emergence of dual-resistant FC428-related strains in Guangdong Province is the result of multiregional population exchanges. Meanwhile, FC428 has increased fitness ( 19 ); thus, the spread of dual-resistant FC428-related clones might have a huge impact on ceftriaxone and azithromycin efficacy. Overall, we should track the prevalence of dual-resistant clones in future surveillance to effectively curb the large-scale spread of dangerous strains.…”

Fascinating Molecular and Immune Escape Mechanisms in the Treatment of STIs (Syphilis, Gonorrhea, Chlamydia, and Herpes Simplex)

“…A Chinese study revealed an increase of the ceftriaxone-decreased-susceptibility from 2.05% (2016) to 16.18% (2019) [ 85 ]. Therefore, this global rapid ascension of the FC428 N. gonorrhoeae jeopardizes the current treatment guidelines and may announce a hereafter global AMR to ceftriaxone and cefixime in gonorrhea patients [ 86 ].…”