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Background: Pelvic pain is a major component of the morbidity associated with urinary tract infection (UTI), yet the molecular mechanisms underlying UTI-induced pain remain unknown. UTI pain mechanisms probably contrast with the clinical condition of asymptomatic bacteriuria (ASB), characterized by significant bacterial loads without lack symptoms., Methods: A murine UTI model was used to compare pelvic pain behavior elicited by infection with uropathogenic Escherichia coli strain NU14 and ASB strain 83972., Results: NU14-infected mice exhibited pelvic pain, whereas mice infected with 83972 did not exhibit pain, similar to patients infected with 83972. NU14-induced pain was not dependent on mast cells, not correlated with bacterial colonization or urinary neutrophils. UTI pain was not influenced by expression of type 1 pili, the bacterial adhesive appendages that induce urothelial apoptosis. However, purified NU14 lipopolysaccharide (LPS) induced Toll-like receptor 4 (TLR4)-dependent pain, whereas 83972 LPS induced no pain. Indeed, 83972 LPS attenuated the pain of NU14 infection, suggesting therapeutic potential., Conclusions: These data suggest a novel mechanism of infection-associated pain that is dependent on TLR4 yet independent of inflammation. Clinically, these findings also provide the rational for probiotic therapies that would minimize the symptoms of infection without reliance on empirical therapies that contribute to antimicrobial resistance.

We obtained, by different methods, isogenic lipopolysaccharide (O antigen) and capsular polysaccharide (K antigen) mutants from Klebsiella pneumoniae strains able to induce experimental infections (cystitis and pyelonephritis) in rats. We compared the induction of experimental infections in rats by wild-type strains and the lipopolysaccharide and capsular polysaccharide mutants. The high-molecular mass lipopolysaccharide of K. pneumoniae is clearly implicated in the infection process of the rat urinary tract, whilst the capsular polysaccharide seems not to be involved to the same extent.

A healthy 54 year old man was investigated for haematuria. In spite of a proven urinary tract infection a cystoscopy was carried out with no antibiotic therapy. As a result he developed systemic infection leading to two independent, and potentially fatal, complications: vertebral osteomyelitis and a mycotic false aneurysm.

Quantitative culture of midstream urine fails to yield a significant microorganism in many patients with acute urinary symptoms. We cultured bladder urine, obtained by aspiration, from symptomatic adults with equivocal findings on standard testing of midstream urine for low numbers of conventional uropathogens and fastidious bacteria. We found 561 (31%) of 1817 women and 36 (12%) of 300 men to be culture positive. Five hundred eighty-one (70%) of 830 isolates were fastidious bacteria; 191 (34%) of 561 culture positive women and 0 of 36 culture-positive men had polymicrobic bacteriuria. Bacterial counts were less than 10(5) colony-forming units/mL in 67% of samples; 204 of 406 patients with single-species infections had increased leukocyte counts in urine. Patients with symptoms of urinary tract infection who are culture negative on standard testing may harbor fastidious bacteria or low numbers of conventional uropathogens in the bladder. In these patients, culture of bladder aspiration urine for low counts and fastidious species is necessary to diagnose bacteriuria.