Epidemiology and Clinical Manifestations of Listeria monocytogenes Infection

Host Epigenetics in Intracellular Pathogen Infections

Some intracellular pathogens are able to avoid the defense mechanisms contributing to host epigenetic modifications. These changes trigger alterations tothe chromatin structure and on the transcriptional level of genes involved in the pathogenesis of many bacterial diseases. In this way, pathogens manipulate the host cell for their own survival. The better understanding of epigenetic consequences in bacterial infection may open the door for designing new vaccine approaches and therapeutic implications. This article characterizes selected intracellular bacterial pathogens, including Mycobacterium spp., Listeria spp., Chlamydia spp., Mycoplasma spp., Rickettsia spp., Legionella spp. and Yersinia spp., which can modulate and reprogram of defense genes in host innate immune cells.

Solid organ donation after death from listeria encephalitis: A case report

Despite organ shortage, organs from donors with listeria infections have been discarded for transplantation. We present the first-reported case of liver transplantation following listeria encephalitis. The patient was admitted with progressing neurological symptoms after an episode of gastroenteritis. Rhombo-encephalitis was diagnosed, and Listeria monocytogenes was found to be the causative pathogen. Despite proper antibiotic treatment and rapid clearance of bacteremia, he continued to deteriorate and became brain dead, after which organ donation was performed. At procurement, he had been treated with amoxicillin for 9 days. The recipient was treated with pipercillin/tazobactam for 21 days. Besides an anastomotic biliary stricture, necessitating endoscopic dilatation and stenting, further clinical course was uneventful and she is doing well eleven months post-transplant. Our case suggests that listeria encephalitis is not an absolute contra-indication to solid organ donation. We suggest that donors should be treated with adequate antibiotics for at least 48h prior to procurement and advocate confirmation of sterile blood cultures as a prerequisite for donation. According to listeriosis guidelines, we suggest that the recipient should be treated with targeted antibiotics for at least 2 weeks. The risk of transmission should, however, always be balanced carefully against the suspected waiting list mortality.

Genome-wide identification of Listeria monocytogenes CodY-binding sites

CodY is a global transcriptional regulator that controls, directly or indirectly, the expression of dozens of genes and operons in Listeria monocytogenes. We used in vitro DNA affinity purification combined with massively parallel sequencing (IDAP-Seq) to identify genome-wide L. monocytogenes chromosomal DNA regions that CodY binds in vitro. The total number of CodY-binding regions exceeded 2,000, but they varied significantly in their strengths of binding at different CodY concentrations. The 388 strongest CodY-binding regions were chosen for further analysis. A strand-specific analysis of the data allowed pinpointing CodY-binding sites at close to single-nucleotide resolution. Gel shift and DNase I footprinting assays confirmed the presence and locations of several CodY-binding sites. Surprisingly, most of the sites were located within genes' coding regions. The binding site within the beginning of the coding sequence of the prfA gene, which encodes the master regulator of virulence genes, has been previously implicated in regulation of prfA, but this site was weaker in vitro than hundreds of other sites. The L. monocytogenes CodY protein was functionally similar to Bacillus subtilis CodY when expressed in B. subtilis cells. Based on the sequences of the CodY-binding sites, a model of CodY interaction with DNA is proposed.