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Background: Investigation of the gut-specific bacterial strains including lactobacilli is essential for understanding the bacterial etiology of constipation., Objective: This study aimed to compare the prevalence and quantity of intestinal lactobacilli in constipated children and healthy controls., Methods: Forty children fulfilling Rome IV criteria for functional constipation and 40 healthy controls were recruited. Fecal samples were analyzed using species-specific polymerase chain reaction followed by random amplified polymorphic DNA-PCR and quantitative real-time PCR., Results: Totally, seven different species of lactobacilli were detected. Out of 80 volunteers, 65 (81.3%) were culture and species-specific PCR positive from which 25 (38.46%) constipated children and 40 (61.54%) healthy subjects. The most prevalent species were L. paracasei 21 (32.3%) followed by L. plantarum 18 (27.7%) among both healthy and patient groups. Analysis of the RAPD dendrograms displayed that strains isolated from constipated and non-constipated children have similarity coefficients of more than 90%. The qPCR assays demonstrated constipated children had a lower amount of total lactobacilli population (per gram of feces) than healthy controls., Conclusion: Our findings showed that the mere existence of various species of Lactobacillus in the gut does not enough to prevent some gastrointestinal disorders such as functional constipation, and their quantity plays a more important role.

Objectives: To evaluate the potential probiotic properties of Lactobacillus strains isolated from feces of infants and also to determine their antimicrobial activity against some enteropathogenic bacteria., Methods: The Fecal samples were prepared from 120 infants aged less than 24 months. In total, 105 Lactobacillus strains were identified by phenotypic tests. Thirty isolates were randomly selected to study their potential probiotic properties. These isolates were examined for resistance to acid (pH: 2.5, 2 h) and bile (oxgall 0.3%, 8 h), adhesion to HT-29 cells, antibiotic susceptibility, and antimicrobial activities., Results: On basis of 16S rRNA sequencing, 30 isolates identified as Lactobacillus fermentum (n = 11; 36.7%), Lactobacillus plantarum (n = 9; 30%), Lactobacillus rhamnosus (n = 6; 20%), and Lactobacillus paracasei (n = 4; 13.3%). All tested strains survived at acid and bile conditions. Six Lactobacillus strains revealed high adherence to HT-29 cells. Three strains including the L. fermentum (N2, N7), and the L. plantarum (N20) showed good probiotic potential and inhibited the growth of Yersinia enterocolitica ATCC 23715, Shigella flexneri ATCC 12022, Salmonella enterica ATCC 9270, and enteropathogenic Escherichia coli (EPEC) ATCC 43887. The antibiotic resistance test showed that all the isolates were susceptible to tetracycline, and chloramphenicol., Conclusions: Lactobacillus strains like L. fermentum (N2, N7), and the L. plantarum (N20), could be potential probiotic, but further in vitro and in vivo studies on these probiotic strains are still required., (Copyright © 2020 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Nabi Jomehzadeh,1– 3 Hazhir Javaherizadeh,4 Mansour Amin,2,3 Mohammad Rashno,1 Ali Teimoori5 1Cellular and Molecular Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran; 2Infectious and Tropical Diseases Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran; 3Department of Microbiology, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran; 4Alimentary Tract Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Khouzestan, Iran; 5Department of Virology, Faculty of Medicine, Hamedan University of Medical Sciences, Hamedan, IranCorrespondence: Mansour AminInfectious and Tropical Diseases Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, IranTel +98 9163061096Fax +98 61-3333 2036Email mnsamin@yahoo.comBackground: Functional constipation is a common and annoying gastrointestinal disorder among children worldwide in which the intestinal microbiota composition plays a fundamental role. This study aimed to compare the quantity of main intestinal Lactobacillus species in constipated children and healthy controls.Materials and Methods: Fecal samples were collected from 40 children fulfilling Rome IV criteria for functional constipation and 40 healthy volunteers. Quantitative real-time polymerase chain reaction (qPCR) method with species-specific primers was used to investigate seven main Lactobacillus species in fecal samples.Results: Lactobacillus strains of the patient group were different from the healthy controls, main differences being noticeable decrease in the population quantity of Lactobacillus reuteri (mean 102.61 CFU/gram feces) and lower abundance of Lactobacillus fermentum (p< 0.0001).Conclusion: Lactobacillus species might be quantitatively altered in childhood functional constipation. Our findings on the different species of Lactobacillus population showed significantly decreased quantity in the patient group compared with the healthy subjects.Keywords: constipation, Lactobacillus, microbiota, quantitative real-time PCR