PIX is an N-terminal delivery domain that defines a class of polymorphic T6SS effectors in Enterobacterales.

The type VI secretion system (T6SS), a widespread protein delivery apparatus, plays a role in bacterial competition by delivering toxic effectors into neighboring cells. Identifying new T6SS effectors and deciphering the mechanism that governs their secretion remain major challenges. Here, we report two orphan antibacterial T6SS effectors in the pathogen Pantoea agglomerans (Pa). These effectors share an N-terminal domain, Pantoea type six (PIX), that defines a widespread class of polymorphic T6SS effectors in Enterobacterales. We show that the PIX domain is necessary and sufficient for T6SS-mediated effector secretion and that PIX binds to a specialized Pa VgrG protein outside its C-terminal toxic domain. Our findings underline the importance of identifying and characterizing delivery domains in polymorphic toxin classes as a tool to reveal effectors and shed light on effector delivery mechanisms.

An antibacterial T6SS in Pantoea agglomerans pv. betae delivers a lysozyme-like effector to antagonize competitors.

The type VI secretion system (T6SS) is deployed by numerous Gram-negative bacteria to deliver toxic effectors into neighbouring cells. The genome of Pantoea agglomerans pv. betae (Pab) phytopathogenic bacteria contains a gene cluster (T6SS1) predicted to encode a complete T6SS. Using secretion and competition assays, we found that T6SS1 in Pab is a functional antibacterial system that allows this pathogen to outcompete rival plant-associated bacteria found in its natural environment. Computational analysis of the T6SS1 gene cluster revealed that antibacterial effector and immunity proteins are encoded within three genomic islands that also harbour arrays of orphan immunity genes or toxin and immunity cassettes. Functional analyses indicated that VgrG, a specialized antibacterial effector, contains a C-terminal catalytically active glucosaminidase domain that is used to degrade prey peptidoglycan. Moreover, we confirmed that a bicistronic unit at the end of the T6SS1 cluster encodes a novel antibacterial T6SS effector and immunity pair. Together, these results demonstrate that Pab T6SS1 is an antibacterial system delivering a lysozyme-like effector to eliminate competitors, and indicate that this bacterium contains additional novel T6SS effectors.

Laparoscopic splenectomy for severe blunt trauma: initial experience of ten consecutive cases with a fast hemostatic technique.

BACKGROUND: Minor splenic injuries from blunt trauma can be treated conservatively, whereas high-grade injuries commonly associated with multiple trauma require surgical treatment and usually removal of the organ. Although splenectomy is nowadays routinely performed laparoscopically for the treatment of hematological pathologies, in an emergency the operational procedure is performed through conventional laparotomy worldwide, advocating the need for hemostasis. Progress in surgical skill and new developments in equipment allow us to treat also patients affected by severe splenic blunt trauma minimally invasively. METHODS: In this study we analyzed 12 patients who consecutively came under our observation during a 2-year period and, being affected by severe spleen injury from blunt trauma requiring surgery, underwent emergency laparoscopy. All of them had Injury Severity Score (ISS) >or= 20 with Glasgow Coma Score (GCS) >or= 10. Laparoscopic splenectomy was performed in ten of the cases utilizing a quick hemostatic technique. In one case bleeding was controlled without removal of the organ and in another case laparoscopy revealed that the supposed hemoperitoneum and splenic rupture were in fact the rupture of a giant splenic cyst. RESULTS: The median operative time to reach hemostasis was 17 min (13-125 min) and the median overall operative time was 120 min (55-210 min). All operations were performed fully laparoscopically. Neither mortality nor morbidity related to abdominal problems was observed. Median postoperative stay was 4 days (3-11 days). CONCLUSION: Laparoscopic approach to splenic blunt trauma requiring surgery is a safe and effective procedure. The described technique allows laparoscopic splenectomy to be performed in an emergency, with much the same hemostatic efficacy as the open technique, but with much better outcome for the patient.

Prognostic evaluation of stage B colon cancer patients is improved by an adequate lymphadenectomy: results of a secondary analysis of a large scale adjuvant trial.

OBJECTIVE: To determine if the extent of lymphadenectomy (number of recovered lymph nodes) was associated with long-term outcome in patients operated on for stage B and C colon cancer. SUMMARY BACKGROUND DATA: Lymphatic spreading is the main prognostic indicator in colon cancer patients, although the optimal extent of lymphadenectomy and its prognostic impact are still unknown. METHODS: In 3,648 patients (median follow-up 3.6 years) enrolled in two consecutive INTACC multicentric trials on adjuvant therapy for colon cancer, we studied the association of the number of recovered nodes with overall survival and relapse free survival by means of univariate and Cox regression analysis. RESULTS: The worst overall survival was related to ages > 65 (risk ratio [RR] = 1.30), higher grading (RR = 1.96). Better overall survival was related to female gender (RR = 0.80) and to higher number of recovered nodes (8-12 nodes, RR = 0.46, 13-17 nodes, RR = 0.76, nodes > or = 18, RR = 0.79). The same pattern was observed for relapse free survival. Longer overall and relapse free survival were related to a higher number of recovered nodes with P =.034 and P =.003 respectively (stratified analysis for absence or presence of positive nodes). Stage B patients with fewer than 7 nodes in the specimen had both shorter overall survival (P =.0000) and relapse free survival (P =.0016) than the other B patients. Outcome of stage C patients was not related to the number of recovered nodes (P =.28 and 0.12 respectively). The interaction test between stage of disease and number of recovered nodes was statistically significant (P =.017). CONCLUSIONS: Stage B patients with a small number of examined nodes may be understaged. Thus, these patients might be considered for adjuvant therapy because of their poorer life expectancy than other stage B patients. For stage C patients, the number of recovered nodes does not seem to affect long-term outcome.