Heat Resistance Mediated by a New Plasmid Encoded Clp ATPase, ClpK, as a Possible Novel Mechanism for Nosocomial Persistence of Klebsiella pneumoniae

Klebsiella pneumoniae is an important opportunistic pathogen and a frequent cause of nosocomial infections. We have characterized a K. pneumoniae strain responsible for a series of critical infections in an intensive care unit over a two-year period. The strain was found to be remarkably thermotolerant providing a conceivable explanation of its persistence in the hospital environment. This marked phenotype is mediated by a novel type of Clp ATPase, designated ClpK. The clpK gene is encoded by a conjugative plasmid and we find that the clpK gene alone renders an otherwise sensitive E. coli strain resistant to lethal heat shock. Furthermore, one third of a collection of nosocomial K. pneumoniae isolates carry clpK and exhibit a heat resistant phenotype. The discovery of ClpK as a plasmid encoded factor and its profound impact on thermal stress survival sheds new light on the biological relevance of Clp ATPases in acquired environmental fitness and highlights the challenges of mobile genetic elements in fighting nosocomial infections

The anti-bacterial iron-restriction defence mechanisms of egg white; the potential role of three lipocalin-like proteins in resistance against Salmonella

Salmonella enterica serovar Enteritidis (SE) is the most frequently-detected Salmonella in foodborne outbreaks in the European Union. Among such outbreaks, egg and egg products were identified as the most common vehicles of infection. Possibly, the major antibacterial property of egg white is iron restriction, which results from the presence of the iron-binding protein, ovotransferrin. To circumvent iron restriction, SE synthesise catecholate siderophores (i.e. enterobactin and salmochelin) that can chelate iron from host iron-binding proteins. Here, we highlight the role of lipocalin-like proteins found in egg white that could enhance egg-white iron restriction through sequestration of certain siderophores, including enterobactin. Indeed, it is now apparent that the egg-white lipocalin, Ex-FABP, can inhibit bacterial growth via its siderophore-binding capacity in vitro. However, it remains unclear whether ex-FABP performs such a function in egg white or during bird infection. Regarding the two other lipocalins of egg white (Cal-γ and α-1-glycoprotein), there is currently no evidence to indicate that they sequester siderophores

Urinary infections in patients with spinal cord injury

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