Gene regulation and virulence mechanisms in the opportunistic pathogen Serratia marcescens

GARCÍA VÉSCOVI, E.

Santos, San Pablo

Mesa redonda; XXI ALAM-Congerso Latinoamericano de Microbiología; 2012

Sociedad Brasilera de Microbiología

Serratia marcescens is an opportunistic human pathogen that represents a growing problem for public health, particularly in hospitalized or immunocompromised patients. However, little is known about factors and mechanisms that contribute to S. marcescens pathogenesis within its host. We showed that once internalized in non-professional phagocytic cells, Serratia is able not only to persist but also to multiply inside a large membrane-bound compartment that displays autophagic-like features. However, he majority of the autophagic-like vacuoles in which Serratia resides and proliferates are non-acidic and have no degradative properties, showing that Serratia is capable to either delay or prevent fusion with lysosomal compartments. These findings revealed that S. marcescens is able to manipulate the host cell traffic pathways, altering the expected progression of autophagosome maturation and generating a suitable niche for survival and proliferation inside the host cell. We characterized the master PhoP/PhoQ signal transduction system in Serratia and demonstrated that this two component system is involved in circumventing the delivery of the Serratia-containing vacuoles to lysosomal compartments. In addition, we will also discuss our recent findings, disclosing the role of the RcsCDB phosphorelay in the regulation of determinants required for a successful interaction of Serratia with the host.