RESUMO
Hypervirulent Klebsiella pneumoniae have been rarely described in Latin America. This work describes the characterization of hypervirulent K. pneumoniae isolates capsular serotype K2 belonging to sequence types 86 and 380. The assays showed the hypervirulent K. pneumoniae highly virulent, which is determined by the plasmid borne virulence genes. At this time, the hypervirulent K. pneumoniae clinical isolates in Mexico are extensively susceptible to antibiotics.
Assuntos
Genótipo , Infecções por Klebsiella/microbiologia , Infecções por Klebsiella/patologia , Klebsiella pneumoniae/classificação , Klebsiella pneumoniae/patogenicidade , Sorogrupo , Animais , Adesão Celular , Modelos Animais de Doenças , Feminino , Humanos , Klebsiella pneumoniae/isolamento & purificação , Dose Letal Mediana , Masculino , México , Camundongos Endogâmicos BALB C , Testes de Sensibilidade Microbiana , Modelos Biológicos , Plasmídeos/análise , Fatores de Virulência/genéticaRESUMO
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.
