Klebsiella pneumoniae is a Gram-negative bacterium of clinical importance, due to its resistance to several antibiotic classes. We have identified 4 clinical isolates of K. pneumoniae sequence type (ST) 392 KPC-3-producing strains from patients at the Istituto Mediterraneo per i Trapianti e Terapie ad Alta Specializzazione (IRCCS-ISMETT), a Southern Italian transplantation health facility, during a routine surveillance for carbapenemase-producing Enterobacterales from in-house clinical samples. Since those were among, to the best of our knowledge, the first KPC-producing K. pneumoniae ST392 isolated in Europe, we assessed their virulence potential, to understand if this particular ST can become an endemic clinical threat. ST392 isolates were investigated to assess their virulence potential, namely resistance to human sera, formation of abiotic biofilms, adhesion to biotic surfaces, exopolysaccharide production and in vivo pathogenesis in the wax moth Galleria mellonella animal model. ST392-belonging strains were highly resistant to human sera. These strains also have a high capacity to form abiotic biofilms and high levels of adhesion to the human epithelial colorectal adenocarcinoma HT-29 cell line. An increase of transcriptional levels of genes involved in serum resistance (aroE and traT) and adhesion (pgaA) was observed when compared with the Klebsiella quasipneumoniae subsp. similipneumoniae strain ATCC 700603 reference strain. Infection of G. mellonella larvae with ST392 clinical isolates showed that the latter were not highly pathogenic in this model. Together, our results indicate that ST392 isolates have the potential to become a strain of clinical relevance, especially in health settings where patients are immunosuppressed, e.g., transplant recipients.

肺炎克雷伯菌是一种具有临床重要性的革兰氏阴性细菌，因为它对几种抗生素都有抗药性。我们已经从意大利南部移植卫生机构的地中海沿岸农业研究所（IRCCS-ISMETT）的患者中鉴定出4株临床分离株，它们分别来自产肺炎克雷伯菌序列类型（ST）392 KPC-3菌株对内部临床样品中产生碳青霉烯酶的肠杆菌的常规监测。据我们所知，由于它们属于第一批生产KPC的肺炎克雷伯菌我们在欧洲分离出ST392，我们评估了它们的毒力潜力，以了解这种特殊的ST是否会成为地方性临床威胁。对ST392分离株进行了研究，以评估其毒力潜力，即蜡蛾Gallella mellonella动物模型中对人血清的抗性，非生物生物膜的形成，与生物表面的粘附，胞外多糖的产生以及体内发病机理。属于ST392的菌株对人血清具有高度抗性。这些菌株还具有形成非生物生物膜的高能力和对人上皮结肠直肠腺癌HT-29细胞系的高水平粘附。涉及血清抗性（aroE和traT）和粘附（pgaA）的基因的转录水平增加）与克雷伯菌肺炎克雷伯菌亚种相比时观察到）。肺炎克雷伯氏菌菌株ATCC 700603参考菌株。用ST392临床分离株感染了G. mellonella幼虫，表明后者在该模型中不是高致病性的。总之，我们的结果表明ST392分离物有可能成为具有临床意义的菌株，尤其是在免疫抑制患者（例如移植受者）的健康环境中。