Lower gastrointestinal tract diseases: Creating a biological model of Klebsiella pneumoniae infection

Abstract

Introduction: Nowadays one of the biggest healthcare burdens is the diseases of the gastrointestinal tract (GIT). Taking into consideration, that the human gut harbors more than 1014 CFU of bacteria, through the years scientists have linked those diseases to bacteria species like: Bacteroides fragilis, Fusobacterium nucleatum, Escherichia coli, and Helicobacter pylori. Nevertheless, according to World Health Organisation (WHO), Klebsiella pneumoniae is the priority pathogen with the main bacterial pool in the gastrointestinal tract and is easily transmitted between patients, leading to nosocomial outbreaks. Therefore, scientific research with dependable murine models of Klebsiella pneumoniae infection in GIT is highly required. Aims & Methods: Within the frames of this study, we aimed to develop a dependable mice model for gastrointestinal tract infection of K. pneumoniae as a method for testing novel antimicrobial therapies. Three different study design settings, overall, six experimental groups, and two bacterial strains (ATCC12657, ATCC43816) were used to test the most effective approach for Klebsiella pneumoniae infection: Control groups (108 CFU: G1 - K. pneumoniae ATCC12657; G4 - K. pneumoniae ATCC43816); antibiotics (penicillin 2000 U/ml, streptomycin 2 mg/ml) pre-treated groups with ampicillin therapy (125 mg/l) (108 CFU: G2 - K. pneumoniae ATCC12657; G3, G5, G6 - K. pneumoniae ATCC43816). Real-time PCR for khe (specific K. pneumoniae gene) and 16S rRNA gene sequencing was performed on DNA extracted from faecal samples of the study animals.Results: The gastrointestinal K. pneumoniae colonization was detected in the antibiotic pre-treated mice group followed by the introduction of K. pneumoniae in all study groups. The control groups of just K. pneumoniae inoculation for three continuous days resulted in (G1) 2,1 x 108 CFU/50mg and (G4) 6.39 x 108 CFU/50mg (p=0,008). To disrupt the host microbiota, the antibiotic pre-treatment in drinking water (streptomycin and penicillin) for three continuous days and low dose ampicillin afterward, were used in two study groups (G2) 6,67 x 108 CFU/50 mg; (G3) 8,24 x 108 CFU/50 mg (p=0,03). Because of sufficient colonization results using three days of antibiotic pre-treatment, one study group was tested with a singular dose of streptomycin and penicillin before bacterial inoculation ((G5) 6,24 x 108CFU/50 mg) and another one with additional ampicillin therapy ((G6) 9,01 x 108CFU/50 mg) (p=0,31). Analysis of the gastrointestinal tract colonization with K. pneumoniae proved effective with or without antibiotic pre-treatment. The effective-ness and differences in microbiota using two bacterial species were also confirmed by 16S rRNA gene sequencing. All above-mentioned results are statistically significant considering p<0.05 with ±95% confidence intervals. Conclusion: Our study demonstrates that colonization of mice intestinal tract by K. pneumoniae can be achieved with or without eradicating resident gut microbiota. Nevertheless, any of the six murine models can be used in further studies of GIT diseases.