Dietary Nitrite Drives Disease Outcomes in Oral Polymicrobial Infections.

Streptococcus mutans resides in the oral polymicrobial biofilm and is a major contributor to the development of dental caries. Interestingly, high salivary nitrite concentrations have been associated with a decreased prevalence of dental caries. Moreover, the combination of hydrogen peroxide-producing oral commensal streptococci and nitrite has been shown to mediate the generation of reactive nitrogen species, which have antimicrobial activity. The goal of this study was to examine whether nitrite affects S. mutans virulence during polymicrobial infections with the commensal Streptococcus parasanguinis. Here, we report that the combination of S. parasanguinis and nitrite inhibited S. mutans growth and biofilm formation in vitro. Glucan production, which is critical for S. mutans biofilm formation, was also inhibited in 2-species biofilms with S. parasanguinis containing nitrite as compared with biofilms that contained no nitrite. In the in vivo caries model, enamel and dentin carious lesions were significantly reduced in rats that were colonized with S. parasanguinis prior to infection with S. mutans and received nitrite in the drinking water, as compared with animals that had a single S. mutans infection or were co-colonized with both bacteria and received no nitrite. Last, we report that S. mutans LiaS, a sensor kinase of the LiaFSR 3-component system, mediates resistance to nitrosative stress. In summary, our data demonstrate that commensal streptococci and nitrite provide protection against S. mutans pathogenesis. Modulating nitrite concentrations in the oral cavity could be a useful strategy to combat the prevalence of dental caries.

Antigen I/II mediates interactions between Streptococcus mutans and Candida albicans.

Streptococcus mutans and Candida albicans are frequently co-isolated from dental plaque of children with early childhood caries (ECC) and are only rarely found in children without ECC, suggesting that these species interact in a manner that contributes to the pathogenesis of ECC. Previous studies have demonstrated that glucans produced by S. mutans are crucial for promoting the formation of biofilm and cariogenicity with C. albicans; however, it is unclear how non-glucan S. mutans biofilm factors contribute to increased biofilm formation in the presence of C. albicans. In this study we examined the role of S. mutans antigen I/II in two-species biofilms with C. albicans, and determined that antigen I/II is important for the incorporation of C. albicans into the two-species biofilm and is also required for increased acid production. The interaction is independent of the proteins Als1 and Als3, which are known streptococcal receptors of C. albicans. Moreover, antigen I/II is required for the colonization of both S. mutans and C. albicans during co-infection of Drosophila melanogaster in vivo. Taken together, these results demonstrate that antigen I/II mediates the increase of C. albicans numbers and acid production in the two-species biofilm, representing new activities associated with this known S. mutans adhesin.

Anomalous biliary and vascular anatomy-Potential pitfalls during cholecystectomy.

Laparoscopic cholecystectomy is usually a low-risk procedure associated with a short stay and a low rate of conversion to open surgery. Complications are sometimes associated with anomalous vascular or biliary anatomy. Outlined below are the variations in vascular and biliary anatomy which may result in complications either due to involvement in the inflammatory process or inadvertent division during dissection. Clin. Anat. 30:1103-1106, 2017. © 2017 Wiley Periodicals, Inc.

An unusual presentation of systemic mastocytosis.

A 47 year old man presented with mastocytosis, a disease process characterised by proliferation of mast cells. The clinical features and outcome are discussed.