Determination of Escherichia coli phylogroups in elderly patients with urinary tract infection or asymptomatic bacteriuria

OBJECTIVES

Distinguishing between urinary tract infection (UTI) and asymptomatic bacteriuria (ABU) is difficult in the geriatric population since specific symptoms are often lacking. Escherichia coli is the most frequent UTI pathogen in this population but also a common urine colonizer. We hypothesized that detecting E. coli phylogroups B2 or D, which were previously associated with virulent strains responsible for extra-intestinal infections outside elderly patients, could help in distinguishing UTI from ABU.

METHODS

Consecutive cases of E. coli bacteriuria diagnosed in hospitalized patients >75 years old during 3 months were investigated for E. coli phylogroups. Multiplex PCR was used to search for several virulence genes as previously described. Characteristics of UTI and ABU cases, assessed retrospectively according to definitions and geriatric expertise, were compared.

RESULTS

Out of 233 bacteriuria cases, 60 were assessed to be UTI and 163 to be ABU, with 10 cases unclassified. E. coli strains belonging to the phylogroups B2 and D were significantly more frequent in UTI (48/60, 80%) than in ABU (101/163, 62%) by univariate and multivariate analyses (OR 3.05, 1.44-6.86, p 0.005). Out of all the host and bacterial characteristics studied, falls (p 0.032), comorbidities (p 0.041), and altered autonomy evaluated by a low activity of daily living score (p 0.027) were also associated with UTI using univariate and multivariate analysis.

CONCLUSIONS

Determination of the E. coli phylogroup, in addition to some host characteristics, can help to distinguish UTI from ABU in elderly patients with bacteriuria. If this hypothesis is confirmed by prospective studies, then inappropriate use of antibiotics may be reduced in ABU cases.

[Stability of P. Falciparum resistance to chloroquine between 1987 and 1989 in Mounana, Gabon]

Between 1987 and 1989 the trend in the chloroquine resistance of Plasmodium falciparum in the mining town of Mounana in south-eastern Gabon was studied in vivo and in vitro in 58 and 158 subjects, respectively, aged from 1 to 15 years. The tests used were a simplified variant of the standard WHO 7-day test for the in vivo study and the isotopic semi-microtest of chemosensitivity for the in vitro study. The health situation in 1989 showed no change from the 1987 situation, but an increase in febrile symptoms suggestive of malaria was observed in 1989. This observation may be linked to a decrease in the distribution of chloroquine since 1987, accompanied by the use of other antimalarials following the appearance of chloroquine-resistant strains. While the parasitological efficacy in vivo remained the same in 1989, there was a decrease in the proportion of strains resistant to chloroquine in vitro compared to 1987; likewise, the therapeutic efficacy as estimated from temperature readings was better in 1989 than in 1987: the modification of the prophylactic strategy since 1986 and the drop in chloroquine consumption since 1987 could be responsible for a stabilization of chloroquine resistance at Mounana. The authors consider it appropriate in this region to continue treating malaria in children with chloroquine (in a dosage of 25 mg/kg) and to use a second-line treatment in the event of the recurrence of malaria symptoms within the next two weeks.