Comparison of Escherichia Coli Strains Recovered From Human Cystitis and Pyelonephritis Infections in Transurethrally Challenged Mice

Abstract

Urinary tract infection, most frequently caused by Escherichia coli, is one of the most common bacterial infections in humans. A vast amount of literature regarding the mechanisms through which E. coli induces pyelonephritis has accumulated. Although cystitis accounts for 95% of visits to physicians for symptoms of urinary tract infections, few in vivo studies have investigated possible differences between E. coli recovered from patients with clinical symptoms of cystitis and that from patients with symptoms of pyelonephritis. Epidemiological studies indicate that cystitis-associated strains appear to differ from pyelonephritis-associated strains in elaboration of some putative virulence factors. With transurethrally challenged mice we studied possible differences using three each of the most virulent pyelonephritis and cystitis E. coli strains in our collection. The results indicate that cystitis strains colonize the bladder more rapidly than do pyelonephritis strains, while the rates of kidney colonization are similar. Cystitis strains colonize the bladder in higher numbers, induce more pronounced histologic changes in the bladder, and are more rapidly eliminated from the mouse urinary tract than pyelonephritis strains. These results provide evidence that cystitis strains differ from pyelonephritis strains in this model, that this model is useful for the study of the uropathogenicity of cystitis strains, and that it would be unwise to use pyelonephritis strains to study putative virulence factors important in the development of cystitis.Although the bladder, particularly in women, is often exposed to bacteria and although urine generally supports bacterial growth, the combined effects of bladder emptying by urination and an intrinsic defense mechanism associated with bladder epithelium assist in resisting bacterial infection of the bladder (4, 28, 29). However, a breach of natural bladder defense mechanisms resulting from anatomical abnormalities of the urinary tract or, more commonly, virulence factors expressed by the colonizing bacteria results in urinary tract infection (UTI). Symptomatic UTI is manifest in two syndromes. One is acute pyelonephritis clinically identified by flank pain and fever and generally perceived as being a kidney infection. The second is cystitis, characterized by dysuria and increased frequency and urgency of urination, which is generally perceived to be a bladder infection and accounts for 95% of all visits to physicians for UTIs (7).In the normal urinary tract, most UTIs are caused by Escherichia coli. Studies on the uropathogenicity of E. coli have focused primarily on the development of pyelonephritis. Epidemiologic studies have implicated adhesins, particularly P fimbriae, and other factors, such as hemolysin, in the development of acute pyelonephritis; some of these have been confirmed to be virulence factors by in vitro and in vivo studies (9,10,(18)(19)(20). Only recently have epidemiologic studies begun to focus on cystitis, the more frequent UTI syndrome. Although some put...

Uropathogenic Escherichia coli Outer Membrane Antigens Expressed during Urinary Tract Infection

“…The CBA/J mouse model of ascending UTI was used as previously described (15,22). To achieve chronic infections, mice were transurethrally inoculated with 1 ϫ 10 9 CFU of E. coli CFT073 three times over a 12-week period, on days 0, 6, and 65.…”

Recent Antimicrobial Susceptibilities for UropathogenicEscherichia coliin Patients with Community Acquired Urinary Tract Infections: A Multicenter Study

“…than E. coli causing acute cystitis, but has a relatively low bacteria colony in the bladder [16][17][18]. In theory, since most of the acute pyelonephritis starts from the bladder, antimicrobial susceptibility of causative organisms of acute cystitis and acute pyelonephritis are expected to be the same.…”

Urinary Tract Immunology

“…The role of neutrophils in immune responses to UPEC-mediated UTI Infected mouse bladders examined histologically display thickening of epithelium accompanied by robust infiltration of inflammatory cells and edema in the lamina propria (85). Neutrophils are the most rapid and abundant responders to the infected urinary tract (85).…”

“…Neutrophils are the most rapid and abundant responders to the infected urinary tract (85). Efficient migration of neutrophils requires intracellular adhesion molecule 1 (ICAM-1) expression by epithelial cells and 2 integrin (CD11b/CD18) expression by neutrophils (30).…”