OBJECTIVES Vancomycin and metronidazole remain the only primary options for the treatment of Clostridium difficile infection (CDI). Recent reports have suggested a superior clinical response to vancomycin therapy compared with metronidazole, but this has been difficult to prove or explain. There are few robust in vitro data of the effects of antibiotic treatment of CDI in a gut reflective setti...

Many of the remaining challenges in infectious disease control involve pathogens that fail to elicit long-lasting immunity in their hosts. Antigenic variation is a common reason for this failure and a contributor to the complexity of vaccine design. Diversifying selection by the host immune system is commonly, and often correctly, invoked to explain antigenic variability in pathogens. However, ...

We present a novel model that describes the within-host evolutionary dynamics of parasites undergoing antigenic variation. The approach uses a multi-type branching process with two types of entities defined according to their relationship with the immune system: clans of resistant parasitic cells (i.e. groups of cells sharing the same antigen not yet recognized by the immune system) that may be...

The Shiga toxigenic Escherichia coli (STEC) O113:H21 strain 98NK2, which was responsible for an outbreak of hemolytic uremic syndrome, secretes a highly potent and lethal subtilase cytotoxin that is unrelated to any bacterial toxin described to date. It is the prototype of a new family of AB(5) toxins, comprising a single 35-kilodalton (kD) A subunit and a pentamer of 13-kD B subunits. The A su...