Sex-dependent differences in behavioral and immunological responses to antibiotic and bacteriophage administration in mice

Abstract

IntroductionThe problem of antibiotic resistance is a global one, involving many industries and entailing huge financial outlays. Therefore, the search for alternative methods to combat drug-resistant bacteria has a priority status. Great potential is seen in bacteriophages which have the natural ability to kill bacterial cells. Bacteriophages also have several advantages over antibiotics. Firstly, they are considered ecologically safe (harmless to humans, plants and animals). Secondly, bacteriophages preparations are readily producible and easy to apply. However, before bacteriophages can be authorized for medical and veterinary use, they must be accurately characterized in vitro and in vivo to determinate safety.MethodsTherefore, the aim of this study was to verify for the first time the behavioral and immunological responses of both male and female mice (C57BL/6J) to bacteriophage cocktail, composed of two bacteriophages, and to two commonly used antibiotics, enrofloxacin and tetracycline. Animal behavior, the percentage of lymphocyte populations and subpopulations, cytokine concentrations, blood hematological parameters, gastrointestinal microbiome analysis and the size of internal organs, were evaluated.ResultsUnexpectedly, we observed a sex-dependent, negative effect of antibiotic therapy, which not only involved the functioning of the immune system, but could also significantly impaired the activity of the central nervous system, as manifested by disruption of the behavioral pattern, especially exacerbated in females. In contrast to antibiotics, complex behavioral and immunological analyses confirmed the lack of adverse effects during the bacteriophage cocktail administration.DiscussionThe mechanism of the differences between males and females in appearance of adverse effects, related to the behavioral and immune functions, in the response to antibiotic treatment remains to be elucidated. One might imagine that differences in hormones and/or different permeability of the blood-brain barrier can be important factors, however, extensive studies are required to find the real reason(s).

Infection and antibiotic-associated changes in the fecal microbiota ofC. rodentiumϕstx2dact-infected C57BL/6 mice

“…Several recent studies described the impact of single and, in some cases, combinations of antibiotics on the intestinal microbiota in mice (30,(32)(33)(34)(35)(36)39). However, a detailed comparative analysis addressing the impact of different classes of antibiotics on the gut microbiota during treatments to eliminate enteric bacterial pathogens has not been performed.…”

“…Differences in the intestinal microbiota composition of mice have been described and may depend on age, gender, genetic background, housing conditions, and others (30). We performed five experiments using independently purchased mouse batches (Batch 1-5).…”

“…Although several studies have investigated the changes in the murine gastrointestinal microbiota composition in response to antibiotic treatment (30)(31)(32)(33)(34)(35)(36)(37), there is little information on the individual influence of different classes of antibiotics on the microbiota composition in a murine infection model. Additionally, there are no studies that assess the impact of infection on the fecal microbiota in the presence and absence of antibiotics with Shiga toxin-producing C. rodentium.…”

“…Very recently, Grabowski et al (30) aimed to analyze the effect of enrofloxacin, however, the control mice exhibited a tremendously high amount of Carnobacteriaceae (~30%) and Pseudomonadaceae (10%) as unusual gut colonizers, which were rapidly depleted preventing any detailed evaluation of antibiotic effects. Severe and long-term changes in the intestinal microbiota were also observed with a combination of four different antibiotics (ampicillin, vancomycin, metronidazole, and neomycin) (30,36,37,39). Here, an increase in Enterococcus and a decrease in probioticsrelated genera such as Lactobacillus was reported as common across individual and mixed antibiotic treatments (37).…”

“…Other studies also included mice with a different, rather unusual naïve mouse microbiota, which also hampered a direct comparison of the antibiotic effects. Very recently, Grabowski et al (30) aimed to analyze the effect of enrofloxacin, however, the control mice exhibited a tremendously high amount of Carnobacteriaceae (~30%) and Pseudomonadaceae (10%) as unusual gut colonizers, which were rapidly depleted preventing any detailed evaluation of antibiotic effects. Severe and long-term changes in the intestinal microbiota were also observed with a combination of four different antibiotics (ampicillin, vancomycin, metronidazole, and neomycin) (30,36,37,39).…”