To assess whether methicillin resistance is a microbial characteristic associated with deleterious clinical outcome, we performed a cohort study on 908 consecutive episodes of Staphylococcus aureus bacteremia and a case-control study involving 163 pairs of patients matched for preexisting comorbidities, prognosis of the underlying disease, length of hospitalization, and age. Of 908 bacteremic episodes, 225 (24.8%) were due to methicillin-resistant S. aureus (MRSA). Multivariate analysis did not reveal that methicillin resistance was an independent predictor for mortality when shock, source of bacteremia, presence of an ultimately or rapidly fatal underlying disease, acquisition of the infection in an intensive care unit (ICU), inappropriate empirical therapy, female sex, and age were taken into account. Nonetheless, methicillin resistance was an independent predictor for shock. The case-control study could not confirm that shock was linked to MRSA when prior antimicrobial therapy, inappropriate treatment, ICU residence, and female sex were considered. Our data suggest that cohort studies tend to magnify the relationship of MRSA with clinical markers of microbial pathogenicity and that this effect is a shortcoming of these kind of studies that is caused by inadequate control for underlying diseases.

Differences in the presence of nine urovirulence factors among clinical isolates of Escherichia coli causing cystitis and pyelonephritis in women and prostatitis in men have been studied. Hemolysin and necrotizing factor type 1 occur significantly more frequently among isolates causing prostatitis than among those causing cystitis (P < 0.0001) or pyelonephritis (P < 0.005). Moreover, the papGIII gene occurred more frequently in E. coli isolates associated with prostatitis (27%) than in those associated with pyelonephritis (9%) (P < 0.05). Genes encoding aerobactin and PapC occurred significantly less frequently in isolates causing cystitis than in those causing prostatitis (P < 0.01 and P < 0.0001, respectively) and pyelonephritis (P < 0.01 and P < 0.0001, respectively). No differences in the presence of Sat or type 1 fimbriae were found. Finally, AAFII and Bfp fimbriae are no longer considered uropathogenic virulence factors since they were not found in any of the strains analyzed. Overall, the results showed that clinical isolates producing prostatitis need greater virulence than isolates producing pyelonephritis in women or, in particular, cystitis in women (P < 0.05). Overall, the results suggest that clinical isolates producing prostatitis are more virulent that those producing pyelonephritis or cystitis in women.Urinary tract infections (UTIs) are one of the most common infectious diseases encountered in the clinical practice, mainly being associated with different members of the family Enterobacteriaceae. In fact, Escherichia coli is by far the most predominant pathogen causing UTIs (4,18,19,21).In general, rates of UTIs are higher among women than among men (15), with cystitis being the most prevalent UTI in women. It is noteworthy that the prevalence of quinolone resistance among E. coli strains causing cystitis is significantly higher than the prevalence of quinolone resistance among strains causing urinary parenchymatous infections such as prostatitis and pyelonephritis (2, 23). Velasco et al. (23) found that 20% of the isolates causing cystitis were resistant to ciprofloxacin, while only 8% of the invasive isolates causing UTIs had a resistant phenotype. Some studies suggest that resistance to the quinolones may be associated with a diminished virulence of the uropathogenic strains (16). Moreover, in a recent work (25), the prevalence of different genes encoding certain virulence factors among quinolone-resistant E. coli isolates causing cystitis and pyelonephritis in women was found to be lower than that among quinolone-susceptible strains.Both host and bacterial factors have been associated with the pathogenesis of these infections (9, 21). Thus, uropathogenic strains of E. coli are believed to display a variety of virulence properties that help them colonize host mucosal surfaces and circumvent host defenses to allow invasion of the normally sterile urinary tract (15,18,21). A number of virulence determinants have been related to the acquisition or development of UTIs. Among these factors, sidero...

To assess the utility of blood cultures in the management of uncomplicated pyelonephritis in women, we prospectively collected data from 583 cases. Discordant cases were defined as those for which the pathogens isolated from urine and from blood were different. We found that 97.6% of cases were nondiscordant. Clinical and microbiological evolution of infection did not differ between the 2 groups, and no changes of antibiotic therapy were required on the basis of blood culture results. Blood culture may not be routinely required for the evaluation of uncomplicated pyelonephritis in women.

DM prevalence among adults with TB in Barcelona is low and remained stable over the 14-year study period. However, TB patients with DM were potentially more infectious and their clinical management was more complicated.