In vivo colonization of the mouse large intestine and in vitro penetration of intestinal mucus by an avirulent smooth strain of Salmonella typhimurium and its lipopolysaccharide-deficient mutant

Abstract

The relative abilities of an avirulent Salmonella typhimurium strain with wild-type lipopolysaccharide (LPS) character, SL5319, and a nearly isogenic LPS-deficient mutant, SL5325, to colonize the large intestines of streptomycin-treated CD-1 mice in vivo and to penetrate colonic mucus in vitro were studied. Previously it had been shown that, when fed simultaneously to streptomycin-treated mice (approximately 10(10) CFU each), the S. typhimurium strain with wild-type LPS colonized at 10(8) CFU/g of feces indefinitely, whereas the LPS-deficient mutant dropped within 3 days to a level of only 10(4) CFU/g of feces. In the present investigation, when SL5325 was allowed to colonize for 8 days before feeding mice SL5319 or when it was fed to mice simultaneously with an Escherichia coli strain of human fecal origin (10(10) CFU each), both strains colonized indefinitely at 10(7) CFU/g of feces. Moreover, when the wild-type and LPS-deficient mutant strains were fed to mice simultaneously in low numbers (approximately 10(5) CFU each) the strains survived equally well in the large intestines for 8 days, after which the LPS-deficient mutant was eliminated (less than 10(2) CFU/g of feces), whereas the wild-type colonized at a level of 10(7) CFU/g of feces. In addition although both strains were able to adhere to mucus and epithelial cell preparations in vitro, the wild-type strain was shown to have greater motility and chemotactic activity on CD-1 mouse colonic mucus in vitro and to more rapidly penetrate and form a stable association with immobilized colonic mucosal components in vitro. Based on these data, we suggest that the ability of an S. typhimurium strain to colonize the streptomycin-treated mouse large intestine may, in part, depend on its ability to penetrate deeply into the mucus layer on the intestinal wall and subsequently, through growth, colonize the mucosa.

Growth of Salmonella typhimurium SL5319 and Escherichia coli F-18 in mouse cecal mucus: role of peptides and iron

“…If so, as S. typhimurium SL5319 penetrates the mucus layer and grows, it might effectively starve S. typhimurium SL5325 for iron, resulting in failure of S. typhimurium SL5325 to grow faster than the mucus is sloughed into the lumen. Since S. typhimurium SL5325 cannot grow in luminal contents [2], sloughed bacterial cells would be rapidly eliminated from the intestine in feces, resulting in the observed inability of S. typhimurium SL5325 to colonize when fed to mice along with S. typhimurium SL5319 [5]. In contrast, since E. coli F-18 cannot use enterochelin, when mice are fed E. coli F-18 and S. typhimurium SL5325, sufficient ferrienterochelin might be available tc the more slowly penetrating S. typhimurium SL5325 at all times, to allow ~ rowth and avoid washout in feces.…”

“…We also reported that when S. typhimurium SL5325 and E. coti F-18, a normal human fecal isolate which also requires growth in cecal mucus to colonize [4], are fed to streptomycin-treated mice, both colonize in high numbers [5]. However~ E. coli F-18 travels through mucus just as quickly as S. typhimurium SL5319 and therefore far more quickly than S. typhimurium SL5325 (unpubl.…”

Roles of motility, chemotaxis, and penetration through and growth in intestinal mucus in the ability of an avirulent strain of Salmonella typhimurium to colonize the large intestine of streptomycin-treated mice

“…Strain SL5316 Nalr, a spontaneous nalidixic acid-resistant mutant of SL5316, unaltered in other characters including colonizing ability, was used in place of SL5316 itself. These strains are able to colonize the streptomycin-treated CD-1 mouse large intestine despite the aroA defect (21,22), presumably because the indigenous anaerobes which continue to colonize the intestine in the presence of streptomycin (21,22) provide the p-aminobenzoate and 2,3-dihydroxybenzoate that S. typhimurium strains require for growth. SL5319 is strain SL5316 made hisD8557::TnJO by transduction and therefore tetracycline resistant but otherwise unaltered in phenotype and was shown previously to colonize as efficiently as its parent (22).…”

“…Although the method used to isolate epithelial cells was originally developed for isolation from the rat small intestine (30), the method works well for isolation of epithelial cells from the CD-1 mouse small intestine (17), colon (21), and cecum. Typically, an entire cecum yields about 107 cells.…”

In vitro Binding of Pasteurella multocida Cell Wall Preparations to Tracheal Mucus of Cattle and Swine and to a Tracheal Epithel Cell Wall Preparation of Cattle

“…multocida (P. m. m.) strains and some strains of other Pasteurella species used in this study are listed in Table 1 Mucus preparation. The preparation of tracheal mucus of cattle and swine was made using a modification of the method described by NEVOLA et al (1987) (16). The tracheae of freshly slaughtered animals were rinsed with ice cold lOmM phosphate buffered saline (PBS) (pH 7.4).…”