Merla C, Kuka A, Mileto I, Petazzoni G, Gaiarsa S, De Vitis D, Ardizzone M, Corbella M, Baldanti F, Cambieri P
Struttura Complessa di Microbiologia e Virologia, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy.
Scuola di Specializzazione in Microbiologia e Virologia, Università degli Studi di Pavia, Pavia, Italy.
Microbiol Spectr. 2024 Jan 30;12(3):e0329223. doi: 10.1128/spectrum.03292-23.
Hypervirulent (hvKp) can cause infections in clinically healthy people, such as young and immunocompetent patients. Genes involved in the capsule synthesis or those encoding the siderophores have been adopted as predictors of hvKp. Certain sequence types, such as ST23 and ST86, have been associated with hvKp strains, too. The aim of this study was to investigate the presence of hvKp among 354 strains isolated from clinical samples of patients admitted to an Italian 900-bed hospital between 21 May 2021 and April 2022. All the isolates were screened by PCR for the amplification of virulence loci. Whole genome sequencing was performed in strains tested positive for at least one target gene. Thirteen out of 354 (3.7%) were hvKp. Five were wild type and belonged to the hypervirulent clones ST23, ST86, ST5, and ST375 and to the new clone ST6310. Six strains carried the gene: three belonged to ST101, two to ST512, and one to ST395. Two isolates were ST147 and carried the gene. Although hvKp isolation is not frequent, their presence should be systematically investigated to avoid the spreading of both virulent strains and strains with combined increase in virulence and resistance to antibiotics. PCR-based protocols are essential for surveillance of these strains, which do not always show a recognizable phenotype. Moreover, hvKp strains were isolated also from patients without history of recent foreign travels, indicating an increased spreading of these strains as well as an underestimated of their circulation so far.IMPORTANCE is a healthcare-associated pathogen frequently resistant to antibiotics. Hypervirulent strains of pneumoniae (hvKp) can spread from the primary site of infection to multiple sites causing life-threatening infections also in young otherwise healthy individuals. This study described the isolation of 13 isolates of with increased virulence in a large tertiary hospital over a 1-year period. Among them, eight strains were multidrug resistant and hypervirulent. Although these hypervirulent strains are still rare in Italy, their presence is particularly concerning since they can cause difficult-to-treat life-threatening infections. Moreover, not all the hypervirulent isolates were positive by the string test, so hvKp isolates were not always phenotypically detectable. Molecular biology techniques such as PCR amplification and next generation sequencing are therefore necessary for the detection of hvKp isolates, and surveillance programs exploiting molecular techniques are highly desirable.
高毒力肺炎克雷伯菌（hvKp）可在临床健康人群中引发感染，比如年轻且免疫功能正常的患者。参与荚膜合成的基因或编码铁载体的基因已被用作hvKp的预测指标。某些序列类型，如ST23和ST86，也与hvKp菌株有关。本研究的目的是调查2021年5月21日至2022年4月期间从一家拥有900张床位的意大利医院收治的患者临床样本中分离出的354株菌株中hvKp的存在情况。所有分离株均通过PCR进行毒力基因座扩增筛选。对至少一个靶基因检测呈阳性的菌株进行全基因组测序。354株中有13株（3.7%）为hvKp。5株为野生型，属于高毒力克隆ST23、ST86、ST5和ST375以及新克隆ST6310。6株携带该基因：3株属于ST101，2株属于ST512，1株属于ST395。2株分离株为ST147且携带该基因。尽管hvKp的分离并不常见，但应系统地调查其存在情况，以避免毒力菌株以及毒力和抗生素耐药性均增加的菌株传播。基于PCR的方案对于监测这些菌株至关重要，因为它们并不总是表现出可识别的表型。此外，hvKp菌株也从近期无国外旅行史的患者中分离得到，这表明这些菌株的传播有所增加，且到目前为止其传播情况被低估。重要性肺炎克雷伯菌是一种与医疗保健相关的病原体，经常对抗生素耐药。高毒力肺炎克雷伯菌（hvKp）可从感染的原发部位扩散至多个部位，在原本健康的年轻人中也可引发危及生命的感染。本研究描述了在一家大型三级医院1年期间分离出13株毒力增强的肺炎克雷伯菌。其中，8株为多重耐药且高毒力。尽管这些高毒力菌株在意大利仍然罕见，但其存在尤其令人担忧，因为它们可导致难以治疗的危及生命的感染。此外，并非所有高毒力分离株通过拉丝试验均呈阳性，因此hvKp分离株并非总是在表型上可检测到。因此，PCR扩增和下一代测序等分子生物学技术对于检测hvKp分离株是必要的，利用分子技术的监测项目非常可取。
