Catalán-Nájera Juan Carlos, Garza-Ramos Ulises, Barrios-Camacho Humberto
a Departamento de Diagnostico Epidemiologico, Centro de Investigacion sobre Enfermedades Infecciosas (CISEI) , Instituto Nacional de Salud Pública (INSP) , Cuernavaca, Morelos , México.
Virulence. 2017 Oct 3;8(7):1111-1123. doi: 10.1080/21505594.2017.1317412. Epub 2017 Apr 12.
Since the hypermucoviscous variants of Klebsiella pneumoniae were first reported, many cases of primary liver abscesses and other invasive infections caused by this pathogen have been described worldwide. Hypermucoviscosity is a phenotypic feature characterized by the formation of a viscous filament ≥5 mm when a bacterial colony is stretched by a bacteriological loop; this is the so-called positive string test. Hypermucoviscosity appears to be associated with this unusual and aggressive type of infection, and therefore, the causal strains are considered hypervirulent. Since these first reports, the terms hypermucoviscosity and hypervirulence have often been used synonymously. However, new evidence has suggested that hypermucoviscosity and hypervirulence are 2 different phenotypes that should not be used synonymously. Moreover, it is important to establish that a negative string test is insufficient in determining whether a strain is or is not hypervirulent. On the other hand, hypervirulence- and hypermucoviscosity-associated genes must be identified, considering that these phenotypes correspond to 2 different phenomena, regardless of whether they can act in synergy under certain circumstances. Therefore, it is essential to quickly identify the genetic determinants behind the hypervirulent phenotype to develop effective methodologies that can diagnose in a prompt and effective way these hypervirulent variants of K. pneumoniae.
自从肺炎克雷伯菌的高黏液性变异株首次被报道以来，全球范围内已描述了许多由该病原体引起的原发性肝脓肿及其他侵袭性感染病例。高黏液性是一种表型特征，当用细菌接种环拉伸细菌菌落时会形成一条≥5毫米的黏性细丝；这就是所谓的阳性拉丝试验。高黏液性似乎与这种异常且侵袭性的感染类型有关，因此，致病菌株被认为具有高毒力。自这些首次报道以来，高黏液性和高毒力这两个术语经常被同义使用。然而，新的证据表明，高黏液性和高毒力是两种不同的表型，不应同义使用。此外，必须明确阴性拉丝试验不足以确定菌株是否具有高毒力。另一方面，鉴于这些表型对应于两种不同的现象，无论它们在某些情况下是否能协同作用，都必须鉴定与高毒力和高黏液性相关的基因。因此，快速鉴定高毒力表型背后的遗传决定因素至关重要，以便开发出能够快速、有效地诊断这些肺炎克雷伯菌高毒力变异株的有效方法。
