Salmonella enterica subsp. enterica serovar Napoli (S. Napoli) ranks among the top serovars causing human infections in Italy, although not common in other European countries. Isolates are generally pan-susceptible or resistant to aminoglycosides only, however data on antimicrobial resistance genes in strains of S. Napoli are limited. Recently an isolate encoding resistance to third generation cephalosporins was reported. This study aimed to characterize plasmid-encoded cephalosporin resistance due to the bla_CTX-M-15 gene in a human S. Napoli isolate in Italy, and to investigate plasmid stability over time.

S. Napoli 16/174478 was confirmed to be ESBL-producing. The bla_CTX-M-15 gene was shown to be located on an IncI1α plasmid of 90,272 bp (50.03 GC%) encoding for 107 coding sequences (CDS). The plasmid was successfully transferred by conjugation to an E. coli 1816 recipient strain (conjugation frequency 3.9 × 10⁻² transconjugants per donor). Transconjugants were confirmed to carry the IncI1α plasmid, and to be ESBL-producing strains as well. Moreover, transconjugant colonies maintained the plasmid for up to 10 passages. The identification of S. Napoli isolates able to produce ESBLs is of great concern, as this pathogen is frequently associated with invasive infections and a higher risk of bacteraemia, and its reservoir has not yet been clearly identified.

沙门氏菌肠道亚种。enterica serovar Napoli ( S. Napoli) 是意大利引起人类感染的顶级血清型之一，尽管在其他欧洲国家并不常见。分离株通常仅对氨基糖苷类具有泛敏感性或耐药性，但是关于S. Napoli菌株中抗菌素耐药性基因的数据是有限的。最近报道了一种编码对第三代头孢菌素耐药的分离株。本研究旨在表征质粒编码头孢菌素耐药性由于BLA _CTX-M-15在人基因S.在意大利那不勒斯分离物，并调查随时间质粒稳定性。

S. Napoli 16/174478 被证实是产 ESBL。所述BLA _CTX-M-15基因显示出被定位在90272碱基对（50.03 GC％）编码107个的编码序列（CDS）的IncI1α质粒。通过缀合将质粒成功转移至大肠杆菌1816受体菌株（缀合频率为3.9 × 10 ^-2转接合子/供体）。经证实，转接合子携带 IncI1α 质粒，并且也是产 ESBL 菌株。此外，转接合集落保持质粒达 10 代。S的鉴定 能够产生 ESBL 的那不勒斯分离株备受关注，因为这种病原体经常与侵袭性感染和更高的菌血症风险有关，而且其宿主尚未明确确定。