Sensibilité aux antibiotiques de souches d'Escherichia coli isolées en 1998 et 1999: résultats d'une enquête multicentrique française

[Frequency and antibiotic susceptibility of bacteria identified in urine]

OBJECTIVE

The authors had for aim to evaluate the frequency of isolation and the antibiotic susceptibility of bacteria responsible for urinary infections among in and out-patients.

METHODS

A retrospective study was carried out at the Microbiology Laboratory of the Mohammed-V Military Instruction Hospital in Rabat, on bacteria isolated from 896 positive cytobacteriologic examinations of urine, from January 1 to December 31, 2005.

RESULTS

Among the 7472 urinary samples, 896 answered the criteria of urinary infection (12%). Urinary infections were more frequent in in-patients (57.8%; sex-ratio F/M=1:16). Enterobacteria were the most frequent (85%) and especially Escherichia coli (44.7%). Gram positive bacteria (11.6%) were more frequently Staphylococcus saprophyticus (3.1%). E. coli was highly resistant to amoxicillin, and sulfamethoxazole, whereas quinolones and aminosides maintained a good activity and third generation cephalosporines remain active (97% of susceptibility). Among the enterobacteria present, 3.2% were resistant to third generation cephalosporines with extended spectrum betalactamase.

[Microbial description of bacteriuria in long-term care facilities: a prospective study in the French Teaching Hospital of Strasbourg]

OBJECTIVE

The authors had for aim to assess, the incidence of symptomatic bacteriuria and the level of antibiotic resistance in bacteria identified in long-term care facilities (LTC).

DESIGN

Symptomatic bacteriuria cases were prospectively collected, during 9 months in the two LTC of the Strasbourg French Teaching Hospital (196 beds).

RESULTS

One hundred and eleven bacteriuria cases were included. They concerned 67 of the 274 residents (cumulative incidence: 2.07/1,000 patients-day). A gram-negative bacillus was identified in 85% of the symptomatic bacteriuria cases, and Escherichia coli in 40%. Sixty percent of the identified bacterial strain was resistant to amoxicillin (Amx-R) and 42% to the clavulanic acid combination (AmC-R). Third generation cephalosporins (3GC) were effective in 90% of Urinary tract infections (UTIs) and fluoroquinolones in 65% (Fq). Four bacterias with broad beta-lactamase spectrum were identified (0.04%) including 3 Enterobacter aerogenes. No yeast infection was diagnosed. E. coli strains were 65% Amx-R and 50% AmC-R. Concerning the Fq-R strains (15%), 50% were cotrimoxazole resistant (Stx-R) and 70% Amx-R; 3GC remained effective (82%).

CONCLUSION

In LTC, multi-drug resistance bacteria are rare and 3GCs seem to be the best first line treatment. Nevertheless, Fq-R is increasing (15 vs 8%), and attention must be paid to the antibiotic therapy used.

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.

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.

[Risk factors for amoxicillin-clavulanate-resistant Escherichia coli in ICU patients]

OBJECTIVE

To determine risk factors of infections with amoxicillin-clavulanate-resistant Escherichia coli in ICU patients.

STUDY DESIGN

Prospective, consecutive sample survey study.

PATIENTS

A consecutive series of 133 patients from whom culture results were positive for E. coli during their ICU stay.

METHODS

Risk factors analysed included demographics, comorbid conditions, and antimicrobial drug exposure. Univariate and multivariate analysis were performed.

RESULTS

Multivariate logistic regression analysis identified only one significant independent factor associated with the emergence of amoxicillin-clavulanate-resistant E. coli: prior use of amoxicillin (odds ratio: 5.45).

CONCLUSION

Clinicians should avoid administering amoxicillin-clavulanate as empiric therapy for possible E. coli infection in patients that have recently been treated with amoxicillin.

[Enzymatic resistance of Escherichia coli to beta-lactams and clinical prevalence]

Escherichia coli (E. coli) is the most frequent bacterium implicated in community-acquired infection as well as in nosocomial infections. This bacterium is characterised by numerous possibilities to acquire resistance mechanisms, even during antibiotic treatment. The main mechanism of resistance is the production of beta-lactamines, enzymes hydrolysing beta-lactam ring. This paper describes enzymatic mechanisms of resistance of E. coli to beta-lactam and indicates the necessity of a good knowledge of the risk factors for resistance to have an adapted good clinical practice in using antibiotics.