1999/08/01 by Stacy M. Burns, Sheila I. Hull · 1 citation
Biochemistry, Genetics and Molecular Biology · Medicine · #Escherichia coli research studies #Clostridium difficile and Clostridium perfringens research #Prion Diseases and Protein Misfolding #Biology #Phagocytosis #Microbiology #Incubation #Mutant #Escherichia coli #Enterobacteriaceae #Bacteria #Capsule #Antigen #Biochemistry #Immunology #Gene
paper · pdf · doi:10.1128/iai.67.8.3757-3762.1999
openalex publication_date 1999/08/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/06/26
To determine the importance of the O75 O antigen and the K5 capsular antigen in resistance to phagocytosis and phagocytic killing, we used previously described O75(-) and K5(-) mutants from an O75(+) K5(+) wild-type uropathogenic Escherichia coli strain in phagocytosis assays with polymorphonuclear leukocytes (PMNs) and monocytes. At a 10-to-1 ratio of bacteria to phagocytes and in the presence of 10% serum, the parental strain GR-12 was resistant to both PMNs and monocytes over a 2-h incubation period. The O75(-) and K5(-) mutants were similar in sensitivity to killing by both PMNs and monocytes, decreasing in viability by 80% in the first hour. Yet, a significant difference in killing between the O75(-) and K5(-) mutants was observed in the first 15 min of incubation. The K5(-) mutant decreased in numbers by almost 60%, while the O75(-) mutant increased in numbers similarly to GR-12 in the first 15 min. The difference in killing was found not to be due to the rate of opsonization. To further determine the mechanism of resistance, a fluorescence assay was used to differentiate attached and internalized bacteria. The K5 capsule hindered the association of both the wild-type strain and the O75(-) mutant in the initial incubation time with PMNs. In conclusion, both the K5 capsule and O75 O antigen play crucial roles in resistance to phagocytosis over time.