Altered colonizing ability for mouse large intestine of a surface mutant of a human faecal isolate of Escherichia coli

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Escherichia coli F-17 S(r) a human faecal isolate, is resistant to the T-series of bacteriophages (i.e. T2 to T7). A T2-sensitive mutant of E. coli F-17 S(r) was isolated following acriflavin treatment. This mutant, E. coli F-17 S(r)T(s) was found to be sensitive to the entire T-series of phages. E. coli F-17 S(r) and E. coli F-17 S(r)T(s) did not differ quantitatively in total LPS content. However, analysis of LPS revealed that a large fraction of E. coli F-17 S(r)T(s) was devoid of O-side-chains. This accounted for the sensitivity of this strain to bacteriophages T3, T4, and T7. In addition, E. coli F-17 S(r)T(s) contained only about half the amount of capsular material contained by E. coli F-17 S(r) accounting for the sensitivity of the mutant to bacteriophages T2, T5, and T6. Although the two strains colonized equally well when fed individually to streptomycin-treated mice, when fed simultaneously to streptomycin-treated mice, E. coli F-17 S(r)T(s) colonized at a level of about 1 x 108 cells (g faeces)-1, whereas E. coli F-17 S(r) colonized at only 1 x 104 cells (g faeces)-1. These studies suggest that bacterial cell surface components modulate the large intestine colonizing ability of E. coli F-17 S(r) in the mouse large intestine.

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Journal of General Microbiology