Mannose-Sensitive and Mannose-Resistant Adherence to Human Uroepithelial Cells and Urinary Virulence of Escherichia coli

137

The role of type 1 pili and P adhesins during the in vivo growth of Escherichia coli inoculated into the urethras of BALB/c mice was studied. Strains which produced type 1 pili when grown in broth but lost this trait when grown on agar (regulated variants) were tested. Broth-grown organisms colonized the bladder of every animal tested, with counts of 103 to 104 viable organisms recovered from bladder homogenates. Agar-grown organisms gave lower rates of infection and the number of viable organisms recovered from bladders was significantly reduced. The degree of inoculum piliation influenced bladder colonization in a direct way: as piliation increased, the number of bacteria recovered from bladders also increased. After intraurethral inoculation, all of the bladders and 44% of the kidneys were colonized on day 1, and by day 5, 94% of the bladders and 16% of the kidneys were positive. Hemagglutination titers remained high for the bladder isolates, but the organisms colonizing the kidneys became significantly less piliated with time. Bacteriuria was unrelated to bladder or renal colonization. Strains that demonstrated random phase variation of type 1 pili during growth on agar produced similar colonizations of the urinary tract with broth-and agar-grown inocula. Strains that produced only P adhesins were less effective in colonizing the urinary tract than were type 1 piliated organisms. Other strains which did not produce pili only minimally colonized the bladder. The results suggest that type 1 pili play an essential role in ascending infections of the urinary tract.

mentioning

confidence: 99%

Relationship of type 1 pilus expression in Escherichia coli to ascending urinary tract infections in mice

Schaeffer¹,

Schwan²,

Hultgren³

et al. 1987

137

“…A major question regarding the pathogenesis of E. coli urinary tract infections is whether the bacteria involved possess special and unique properties relative to random members of the normal fecal flora. Most E. coli pyelonephritis isolates agglutinate human erythrocytes in the presence of mannoseresistant hemagglutination (MRHA+) and adhere to uroepithelial cells, whereas only a small proportion of normal fecal strains share these properties (8,27). Adhesion appears to be mediated by a unique pilus protein (pap pili; 11).…”

mentioning

confidence: 99%

Gene clusters governing the production of hemolysin and mannose-resistant hemagglutination are closely linked in Escherichia coli serotype O4 and O6 isolates from urinary tract infections

Low¹,

David²,

Lark³

et al. 1984

113

The genes encoding alpha-hemolysin and mannose-resistant hemagglutination were shown to be closely linked in cloned DNA from two Escherichia coli urinary tract isolates of serotypes 04 (J96) and 06 (C1212). DNA hybridization experiments demonstrated that the hly and mrh gene clusters of other E. coli 06 serotypes were also linked. Colony hybridizations showed that most normal fecal E. coli do not contain hly and mrh DNA but much of the intervening DNA between these two gene clusters is common among all E. coli. We have further demonstrated that there is a small (about 1 kilobase) region of homology located on both sides of the hly sequence and present elsewhere in the C1212 strain. We suggest that linkage of hly and mrh occurred through a transposition event, and we discuss the potential significance of this linkage in the acquisition of virulence determinants by these bacteria.

“…As part of a study of the role of hemolysin in UTI, we examined hemolytic and nonhemolytic E. coli causing symptomatic and asymptomatic infections with respect to factors implicated in extraintestinal infection, i.e., adherence to urinary tract epithelial cells (7,14,28,29), resistance to normal human serum (1,2,12,18), and toxicity (10,17,27), relating findings to the carriage, particularly in specific combinations, of 0, K, and HA antigens and colicin V production.…”

mentioning

confidence: 99%

Hemolysin Production as a Virulence Marker in Symptomatic and Asymptomatic Urinary Tract Infections Caused by Escherichia coli

Hughes¹,

Hacker²,

Roberts

et al. 1983

112

Potential virulence, as defined by combined levels of adhesion to urinary epithelial cells, serum resistance, and mouse toxicity, was assessed for Escherichia coli strains causing symptomatic and asymptomatic urinary tract infections in relation to the carriage of hemolysin and other suspected virulence determinants. Hemolysin production (Hly), associated with certain 0 (04, 06, 018, and 075), K (5), and hemagglutination (VI and VII) antigenic types but not colicin V production (Cva), was evident in 83 and 60% of isolates in groups possessing high potential virulence and in only 11 and 6% of those with low virulence. Strains of particular 0-types were not more virulent per se, but among the serotypes, specific combinations of virulence factors appeared decisive, e.g., 018 HAVI B/D/G Hly+ K5'/and 018 HAIII/IVB/V Hly-Cva'/-K1'/strains were, respectively, of high and low potential virulence. Isolates with high potential virulence were found to a similar extent in symptomatic and asymptomatic infections. 546 on July 3, 2020 by guest http://iai.asm.org/ Downloaded from