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Among 231 clinical strains of Escherichia coli tested during may 1992, 89 isolates (38.5%) were resistant to beta-lactams. The resistant strains were principally recovered from urinary and genital specimen from medicine and surgical departments. MICs of beta-lactams were determined alone or combined with clavulanic acid, and beta-lactamases were identified by isoelectric point characterization and by enzymatic inhibition tests. Among the resistant strains, 92.1% were secreting a penicillinase and 6.7% a cephalosporinase. No extended-spectrum beta-lactamase was observed. 85.5% of penicillinases were TEM-1 enzymes, 4.9% SHV-1 beta-lactamase, 1.1% OXA-1 beta-lactamase and 8.5%, 7 strains, were IRT beta-lactamases (formerly called TRI). For 24 clinical E. coli strains, the MICs values were > or = 32 mg/l for amoxicillin plus clavulanic acid. The 7 IRT beta-lactamases showed the highest MICs, 256 to 4096 mg/l. Four of them exhibited a beta-lactamase of pI 5.4 and 3 a beta-lactamase of pI 5.2. The IRT beta-lactamases represent 3% of all the Escherichia coli strains. This frequency is comparable or lower than the values reported by other studies conducted between 1992 and 1994.

Objectives: Bacteriological data indicate that there is an increased incidence of Streptococcus pneumoniae strains with an intermediate sensitivity to penicillin. The goals of the present study was i) to investigate the profile of sensitivity of Streptococcus pneumoniae isolated from patients with bacterial pneumonia in the area of Montpellier and ii) to compare this profile with the findings of the national center registry to better appreciate geographical specificity., Methods: Fifty-six patients with bacterial pneumonia were enrolled into the study. From September 1989 to March 1994, we performed bacterial sampling including blood cultures, protected brushes and bronchoalveolar lavage specimens. We examined the antibiotic sensitivity of the germs which were isolated. All patients were followed using clinical and radiological criteria., Results: A precise bacteriological diagnosis was established in 83.6% of the population. Streptococcus pneumoniae was found in 47.2% of the samples. In 19%, the strains displayed an intermediate sensitivity to penicillin. All patients recovered., Conclusion: We found a higher rate of resistance to penicillin in Montpellier than the common rate of the national reference center in France. The location of Montpellier closed to the Spanish border might, at least in part, explain this difference.

Objectives: Since the clinical introduction of fluoroquinolones in general practice for the treatment of a wide range of infections, we have carried out an annual survey of the susceptibilities of Enterobacteriaceae, Staphylococcus and Pseudomonas aeruginosa isolated from domiciliary infections to quinolones (nalidixic acid and ofloxacin) as well as to amoxycillin, co-amoxyclav and co-trimoxazole., Methods: From 1990 to 1993, within the same three month period of the year, a total of 1750 strains were collected at three private clinical laboratories in greater Paris. The in vitro activities of antibiotics were evaluated using the standard disc-diffusion test. MICs of ofloxacin were determined for all intermediate and resistant strains., Results: Resistance to quinolones remained unchanged during this four year period. Among Enterobacteriaceae, less than 3% of strains were resistant to fluoroquinolones. A regular decrease in the annual percentage of co-amoxyclav susceptible strains was noted: from 82.4% in 1990 to 68.1% in 1993 (p < 0.001). Resistance (intermediate plus resistant strains) was more frequent in patients more than 60 years old, in those who had received quinolones up to one month before specimen collection or in those who had been recently (within 3 months) hospitalised. Similar data were obtained for amoxycillin or co-amoxyclav., Conclusion: Our study, together with those performed by other European investigators, demonstrates that the prevalence of quinolone resistant strains in general practice remains low and stable despite high consumption of fluoroquinolones.

Pseudomonas aeruginosa strains belonging to the serogroup O:11 exhibiting susceptibility to ticarcillin (TIC) and resistance to the ticarcillin-clavulanic acid (CA) combination were found in 19 inpatients over a 14 month period. Mean inhibition diameters obtained using the agar diffusion method were 21.75 mm around the TIC disks (75 micrograms) and 15.96 mm around the TIC+CA disks (75 + 10 micrograms). With control PaO:11 strains, these diameters were 25.27 and 25 mm, respectively. MIC for ticarcillin determined using the checkerboard method rose to 64 mg with CA levels of 16 mg/l or more. CA exhibited dose-dependent antagonism on TIC killing curves when TIC levels approximated the MIC; this effect was no longer present with higher TIC levels. In the crude bacterial extract, a betalactamase of the cephalosporinase type was detected in the absence of induction and increased threefold after exposure to cefoxitin (100 mg/l) and fourfold after exposure to CA (5 mg/l). All these PaO:11 strains exhibited the same antimicrobial resistance phenotype with decreased susceptibility to ureidopenicillins and resistance to aminoglycosides and fluoroquinolones. The induction of a chromosome-encoded cephalosporinase by CA proved useful as an epidemiologic marker. Nosocomial spread of this phenotype was likely the result of selection due to use of antimicrobials.

In 210 strains of Enterobacteriaceae which were isolated in four hospitals and which showed reduced susceptibility to cefotaxime, high synergy was demonstrated between amoxicillin (20 micrograms) + clavulanate (10 micrograms) and cefotaxime (30 micrograms) using a simple double-disk test. Isoelectric focusing on gel and specific iodometric detection using ceftriaxone identified four extended broad-spectrum beta-lactamases (isoelectric points 7.6, 6.3, 7.0 and 5.9) produced by the strains.