Effect of Ginsenoside-Rh2 and Curcurbitacin-B on Cryptosporidium parvum in vitro.

Ginsenoside-Rh2 and cucurbitacin-B (CuB) are secondary metabolites of Ginseng (Panax ginseng) and Cucurbitaceae plants respectively. We assessed the anticryptosporidial activity of these two functional compounds in a cell culture model of cryptosporidiosis. The highest concentration of each compound that was not toxic to the host cells was used to assess the activity against C. parvum during infection/invasion and growth in HCT-8 cell monolayers. Monolayers were infected with pre-excysted C. parvum oocysts. Infected monolayers were incubated at 37 °C for 24 h and 48 h in the presence of different concentrations of each test compound. A growth resumption assay was performed by incubating infected monolayers in the presence of compounds for 24 h followed by a second 24-h incubation in the absence of compound. To screen for invasion inhibiting activity, freshly excysted C. parvum sporozoites were pre-treated with different concentrations of compounds prior to adding them to the cell monolayers. Paromomycin, a known inhibitor of C. parvum, and DMSO were used as positive and negative control, respectively. The level of infection was initially assessed using an immunofluorescent assay and quantified by real-time PCR. Both compounds were found to strongly inhibit C. parvum intracellular development in a dose-dependent manner. IC50 values of 25 µM for a 24 h development period and 5.52 µM after 48 h development were measured for Rh2, whereas for CuB an IC50 value of 0.169 µg/ml and 0.118 µg/ml were obtained for the same incubation periods. CuB also effectively inhibited resumption of growth, an activity that was not observed with Rh2. CuB was more effective at inhibiting excystation and/or host cell invasion, indicating that this compound also targets extracellular stages of the parasite.

Development of SYN-004, an oral beta-lactamase treatment to protect the gut microbiome from antibiotic-mediated damage and prevent Clostridium difficile infection.

The gut microbiome, composed of the microflora that inhabit the gastrointestinal tract and their genomes, make up a complex ecosystem that can be disrupted by antibiotic use. The ensuing dysbiosis is conducive to the emergence of opportunistic pathogens such as Clostridium difficile. A novel approach to protect the microbiome from antibiotic-mediated dysbiosis is the use of beta-lactamase enzymes to degrade residual antibiotics in the gastrointestinal tract before the microflora are harmed. Here we present the preclinical development and early clinical studies of the beta-lactamase enzymes, P3A, currently referred to as SYN-004, and its precursor, P1A. Both P1A and SYN-004 were designed as orally-delivered, non-systemically available therapeutics for use with intravenous beta-lactam antibiotics. SYN-004 was engineered from P1A, a beta-lactamase isolated from Bacillus licheniformis, to broaden its antibiotic degradation profile. SYN-004 efficiently hydrolyses penicillins and cephalosporins, the most widely used IV beta-lactam antibiotics. In animal studies, SYN-004 degraded ceftriaxone in the GI tract of dogs and protected the microbiome of pigs from ceftriaxone-induced changes. Phase I clinical studies demonstrated SYN-004 safety and tolerability. Phase 2 studies are in progress to assess the utility of SYN-004 for the prevention of antibiotic-associated diarrhea and Clostridium difficile disease.

A hundred-year retrospective on cryptosporidiosis.

Tyzzer discovered the genus Cryptosporidium a century ago, and for almost 70 years cryptosporidiosis was regarded as an infrequent and insignificant infection that occurred in the intestines of vertebrates and caused little or no disease. Its association with gastrointestinal illness in humans and animals was recognized only in the early 1980s. Over the next 25 years, information was generated on the disease's epidemiology, biology, cultivation, taxonomy and development of molecular tools. Milestones include: (i) recognition in 1980 of cryptosporidiosis as an acute enteric disease; (ii) its emergence as a chronic opportunistic infection that complicates AIDS; (iii) acknowledgement of impact on the water industry once it was shown to be waterborne; and (iv) study of Cryptosporidium genomics.