Protective role of intestinal flora against infection with Pseudomonas aeruginosa in mice: influence of antibiotics on colonization resistance

Abstract

Swiss white mice were given ampicillin, clindamycin, kanamycin, metronidazole, or streptomycin in drinking water for a period of 3 weeks. One week after the initiation of antibiotic administration, the treated mice and untreated control mice were challenged orally with approximately 108 viable, streptomycin-resistant (SR) Pseudomonas aeruginosa isolates. All five of the antibiotics decreased the resistance of the mice to intestinal colonization with SR P. aeruginosa, as reflected by an increased fecal carriage of the organism and an increase in population levels of SR P. aeruginosa in feces as compared with untreated controls. Metronidazole was least effective in this regard. The antibiotics lowered the dose of SR P. aeruginosa that resulted in implantation in 50% of the mice ID50 to various degrees. Administration of streptomycin, the most effective antibiotic, caused a 10,000-fold decrease in ID50 as compared with untreated controls. Oral inoculation of approximately 108 organisms of SR P. aeruginosa resulted in translocation of the organism to the * Corresponding author.

DefiningEscherichia colias a health-promoting microbe against intestinalPseudomonas aeruginosa

“…One reason for P. aeruginosa being benign in the human gut should be through the action of intestinal microbiota, which are part of the host defense to intestinal infection (Kamada et al 2013, Schubert et al 2015, Ge et al 2017. Previous studies describe the use of antibiotic cocktails that favor P. aeruginosa intestinal colonization by compromising resistance by the intestinal microbiota (Hentges et al 1985). Accordingly, we show that antibiotic use in mice diminishes all the prevalent phyla, eradicates E. coli, and induces dysbiosis.…”

Conjugal transfer of aminoglycoside and macrolide resistance between Enterococcus faecium isolates in the intestine of streptomycin-treated mice

“…In vivo transfer experiments were carried out in the intestine of streptomycin-treated mice as previously described by Hentges and co-workers [22][23][24]. The recipient was allowed to establish in the intestine for 5 days before the donor strain was inoculated.…”

“…Six female NMRI mice (20 AE 2 g) (Taconic M&B, Ry, Denmark), caged two by two, with an intact normal flora were treated with 5000 mg l À1 streptomycin sulphate in the drinking water according to Hentges and co-workers [22][23][24]. After 24 h, fecal samples were taken, homogenized in 0.9% (w/v) NaCl and plated on Bile Aesculin Azide agar plates (Difco, Detroit, USA) with either 10 mg l À1 erythromycin, 25 mg l À1 fusidic acid, 25 mg l À1 rifampin or 10 mg l À1 erythromycin or Table 1 Primerlist…”

Influence of Intestinal Microflora on Murine Bone Marrow and Spleen Macrophage Precursors

“…The indigenous microflora has been demonstrated to play an important role in host resistance to infection [1][2][3]. It may contribute to this protective effect, first, by limiting intestinal colonization with potential pathogens through bacterial competition [4,5], and, second, by priming the immunological defence mechanisms against invading pathogens [6]. Using germ-free animals, it has been shown that the absence of flora impairs the development of the immune system and decreases specific as well as non-specific immune responses [7][8][9].…”