Helicobacter pylori have coevolved with mankind since its origins, adapting to different human groups. In America H. pylori has evolved in several subpopulations specific for regions or even countries. In this study we analyzed the genome of 163 Colombian strains along with 1,113 strains that represent worldwide H. pylori populations to better discern the ancestry and adaption to Colombian people. Population structure was inferred with FineStructure and chromosome painting identifying the proportion of ancestries in Colombian isolates. Phylogenetic relationship was analyzed using the SNPs present in the core genome. Also, a Fst analysis was done to identify the gene variants with the strongest fixation in the identified Colombian subpopulations in relation to their parent population hspSWEurope. Worldwide, population structure analysis allowed the identification of two Colombian subpopulations, the previously described hspSWEuropeColombia and a novel subpopulation named hspColombia. In addition, three subgroups of H. pylori were identified within hspColombia that follow their geographic origin. The Colombian H. pylori subpopulations represent an admixture of European, African and Native indigenous ancestry; although some genomes showed a high proportion of self-identity, suggesting a strong adaption to these mestizo Colombian groups. The Fst analysis identified 82 SNPs significantly fixed in 26 genes of the hspColombia subpopulation that encode mainly for outer membrane proteins and proteins involved in central metabolism. The strongest fixation indices were identified in genes encoding the membrane proteins HofC, HopE, FrpB-4 and Sialidase A. These findings demonstrate that H. pylori has evolved in Colombia to give rise to subpopulations following a geographical structure, evolving to an autochthonous genetic pool, drive by a positive selective pressure especially on genes encoding for outer membrane proteins.

Introduction: The frozen section procedure is an intraoperative diagnostic method widely used and useful for surgical decision making; which minimizes costs and optimizes staging. Objectives: This research assesses the diagnostic accuracy of frozen section in an intermediate care center, analyzes the factors that may be involved in misdiagnosis and compares the results of the original study with other studies. Materials and methods: This is a cross-sectional study in which the diagnostic accuracy was evaluated and a univariate analysis was performed in a sample of 417 cases that underwent a frozen section. The characteristics of the samples were registered along with the concordance or discordance between the frozen section and the final diagnosis. In addition, a systematic review was made using the Pubmed database in order to compare results with previous studies. Results: The sample included predominantly females with a mean age of 50 years. The sensitivity and specificity of malignancies was 89% and 100% respectively and the sensitivity for borderline tumors was lower (73%). Specimens equal or larger than 10cm and patients with age ≥ 50 years showed association to misdiagnosis when using frozen sections. For example, the analysis of 300 ovary specimens showed association to misdiagnosis in borderline, epithelial and stromal tumors. Conclusions: The frozen sections continue to be the best tool for quick intraoperative diagnostic, and even with some inaccuracies in the diagnosis, this don’t harm the clinical and surgical practice.