Escherichia coli : sensibilité aux -lactamines et diversité génomique des souches isolées en Franche-Comté

Susceptibility of Escherichia coli to the amoxycillin-clavulanate combination: which recommendations should be used to provide relevant information to clinicians?

This study compared MIC distributions of amoxycillin-clavulanate obtained with NCCLS and French (Comite de l'Antibiogramme de la Societe Francaise de Microbiologie; CA-SFM) methodologies for Escherichia coli isolates from urine that were non-susceptible to amoxycillin-clavulanate by the disk diffusion method. With the NCCLS and CA-SFM methods, 74% and 13%, respectively, of these isolates were susceptible to amoxycillin-clavulanate. Therefore, the apparent relatively poor efficacy of amoxycillin-clavulanate against E. coli in French hospitals probably reflects a methodological difference rather than a localised resistance problem. This implies that amoxycillin-clavulanate could be used as an alternative to fluoroquinolones for treatment of E. coli urinary tract infections. Susceptibility tests for amoxycillin-clavulanate should be standardised worldwide.

Bactériémies à Escherichia coli d’origine urinaire

OBJECTIVE

To describe patients with bacteremia from urinary tract infection caused by Escherichia coli and investigate risk factors for mortality.

METHOD

Retrospectively study of the files of patients with bacteremic urinary tract infection caused by E. coli and admitted via the Emergency Department of the University Hospital in Nice between 01/01/1997 and 12/31/2000. Inclusion criteria included at least one blood and urine culture positive for E. coli during the first 48 hours and age above 15 years.

RESULTS

There were 118 patients in the population (71% female). Mean age was 73 years and median age 79 years. The majority of patients (90%) were hospitalized in a medical department. Initially the clinical picture was sepsis in 80% of patients, severe sepsis in 15% and septic shock in 5%. Lethality was 16%. In 40% of cases death occurred within the first 48 hours. Risk factors for mortality in multivariate analysis were initially severe clinical status and male sex.

CONCLUSION

The population was aged and mortality was high for an infection presumed to be relatively benign. Age was not a risk factor for mortality, contrary to male gender.

Escherichia coli : résistance aux quinolones et aux β-lactamines des souches cliniques isolées en Franche-Comté

AIM OF THE STUDY

Numerous European studies have reported an increase of resistance to quinolones among E. coli. We conducted a regional study to update our knowledge on this evolution.

MATERIALS AND METHODS

We evaluated the resistance phenotype and genotype of 115 clinical strains of E. coli. We collected data on individual treatment with fluoroquinolones, and the evolution of the use of these antimicrobial agents.

RESULTS

Resistance to nalidixic acid and ciprofloxacin was 13.0 and 6.9, respectively. The frequency of resistance increased from 1999 to 2001, from 7.5% to 13.0% for nalidixic acid and from 5.4% to 6.9% for fluoroquinolones. Resistance to quinolones was significantly associated to beta-lactams resistance and was slightly higher for nosocomial isolates compared to community-acquired isolates. Previous treatment with fluoroquinolones was the major risk factor associated to E. coli resistance. From 1997 to 2001, fluoroquinolones use has increased in our hospital and particularly in the community. Analysis of molecular epidemiology shows a large clonal diversity among E. coli isolates.

CONCLUSION

This study confirms the evolution through resistance to quinolones of E. coli isolates. This observation is not due to dissemination of resistant clonal strains and the selective pressure exerted by fluoroquinolones influences this evolution. Therapeutic alternatives, surveillance, and restriction of fluoroquinolones use are needed to control this spread of resistance.