For ∼30 years, two distinct groups of clinical isolates of Klebsiella pneumoniae have been recognized. Classical strains (cKp) are typically isolated from patients with some degree of immunocompromise and are not virulent in mouse models of infection whereas hypervirulent strains (hvKp) are associated with community acquired invasive infections and are highly virulent in mouse models of infection. Hyperproduction of capsule and a hypermucoviscous colony phenotype have been strongly associated with the hypervirulence of hvKp strains. Recent studies have begun to elucidate the relationship between capsule gene expression, hypermucoviscosity and hypervirulence. Additionally, genes associated with hyperproduction of capsule and hypermucoviscosity in hvKp strains have been identified in a few cKp isolates. However, it is not clear how the acquisition of these genes impacts the virulence of cKp isolates. A better understanding of the potential risks of these strains is particularly important given that many of them are resistant to multiple antibiotics, including carbapenems.

中文翻译：

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肺炎克雷伯菌中荚膜基因表达，高黏黏度和高毒力的交集。

大约30年以来，已认识到两组截然不同的肺炎克雷伯菌临床分离株。典型菌株（cKp）通常是从具有一定程度免疫妥协的患者中分离出来的，并且在小鼠感染模型中没有毒性，而高毒力菌株（hvKp）与社区获得性侵袭性感染相关，在小鼠感染模型中具有高毒性。胶囊的过度生产和粘膜粘液菌落过多的表型与hvKp菌株的高毒力密切相关。最近的研究已经开始阐明胶囊基因表达，黏膜黏稠度和高毒力之间的关系。另外，已经在一些cKp分离物中鉴定出与hvKp菌株中的胶囊超量生产和粘膜黏度高相关的基因。然而，尚不清楚这些基因的获取如何影响cKp分离株的毒力。鉴于其中许多菌株对多种抗生素（包括碳青霉烯）有抗性，因此更好地了解这些菌株的潜在风险尤为重要。