Feasibility and diagnostic effectiveness of new capsule endoscopy techniques

Since its approval by FDA in 2001, capsule endoscopy revolutionized the study of small bowel. One of the main limitations of its diffusion has been the high cost. More recently, a new videocapsule system (OMOM CE) has been developed in China and obtained the CE mark. Its cost is approximately half that of other capsule systems. However, there are few studies regarding the clinical experience with this new videocapsule system and none of them has been performed in the western world. Among the limitations of capsule endoscopy, there is also one linked to the diagnostic yield. The rapid transit of the device in the proximal segments implies a high risk of false negatives; an indirect confirmation of this limit is offered by the poor ability to identify the papilla of Vater. In addition, recent studies show that in patients with obscure gastrointestinal bleeding, the negative outcome of capsule endoscopy is correlated to a significant risk of recurrence of anemia in the short term, as well as the presence of small bowel lesions documented by a second capsule endoscopy. It was recently approved the use of a new device called "CapsoCam" (CapsoVision, Inc. Saratoga) characterized by four side cameras that offer a panoramic view of 360 degrees, instead of the front to 160°. Two recent pilot studies showed comparable safety profiles and diagnostic yield with the more standardized capsule. Namely, side vision has made possible a clear visualization of the papilla in 70% of cases. The aim of our study is to evaluate the feasibility and diagnostic yield of these two new devices, which first may allow a reduction in costs. Moreover, their complementary use could lead to a recovery diagnostic in patients with false negative results in an initial investigation.

Exploring the biofilm of Streptococcus agalactiae to identify virulence factors

Streptococcus agalactiae, also known as Group B Streptococcus (GBS) is the primary colonizer of the anogenital mucosa of up to 40% of healthy women and an important cause of invasive neonatal infections worldwide. Among the 10 known capsular serotypes, GBS type III accounts for 30-76% of the cases of neonatal meningitis. Biofilms are dense aggregates of surface-adherent microorganisms embedded in an exopolysaccharide matrix. Centers for Disease Control and Prevention estimate that 65% of human bacterial infections involve biofilms (Post et al., 2004). In recent years, the ability of GBS to form biofilm attracted attention for its possible role in fitness and/or virulence. Here, a new in vitro biofilm formation protocol was developed to guarantee more stringent conditions, to better discriminate between strong-, low- and non- biofilm forming strains and reduce ambiguous data interpretation. This protocol was applied to screen the in vitro biofilm formation ability of more than 350 GBS clinical isolates from pregnant women and neonatal infections belonging to different serotype, in relation to media composition and pH. The results showed the enhancement of GBS biofilm formation in acidic condition and identified a subset of isolates belonging to serotypes III and V that forms strong biofilms in these conditions. Interestingly, the best biofilm formers belonged to the serotype III hypervirulent clone ST-17.It was also found that pH 5.0 induces down-regulation of the capsule but that this reduction is not enough by itself to ensure biofilm formation. Moreover, the ability of proteinase K to strongly inhibit biofilm formation and to disaggregate mature biofilms suggested that proteins play an essential role in promoting GBS biofilm formation and contribute to the biofilm structural stability. Finally, a set of proteins potentially expressed during the GBS in vitro biofilm formation were identified by mass spectrometry.