Surveillance of antibiotic resistance in non invasive clinical isolates of Streptococcus pneumoniae collected in Belgium during winters 2003 and 2004.

A total of 391 and 424 non-invasive isolates of Streptococcus pneumoniae collected by 15 laboratories during the 2003 and 2004 survey were tested for their susceptibility by a microdilution technique following NCCLS recommendations. Insusceptibility rates (IR) in the two surveys (2003/2004) were as follows: penicillin 15.0/14.7% [8.4/6.4% Resistance (R)], ampicillin 17.4/14.6% (R 9.0/7.1%), amoxicillin +/- clavulanic acid 2.6/1.2 % (R 0/0%), cefaclor 14.3/14.1% (R 11.5/13.4%), cefuroxime 13.6/12.7% (R 10.5/11.8%), cefuroxime-axetil 10.5/11.8% (R 10.0/9.2%) (breakpoints based on 250 mg), cefotaxime 4.9/6.2% (R 1.3/2.4%), ceftazidime NotTested (NT)/6.4 (R NT/2.6%), cefepime NT/6.4 (R NT/2.6%), imipenem 7.7/8.9 % (R 1.8/1.4%), ertapenem 0.8/NT% (R O/NT%), ciprofloxacin 13.8/9.0% (R 4.3/2.4%), levofloxacin 3.3/2.8% (R 1.5/0.2%), moxifloxacin 0.6/0.2% (R 0.3/0%), ofloxacin 13.5/9.0% (R 4.3/2.4%), erythromycin 26.1/24.7% (R 25.3/24.5%), azithromycin 25.4/24.7% (R 24.6/24.5%), telithromycin 0.8/0.2% (R 0.5/0%), clindamycin 21.2/18.4% (R 19.2/17.7%) and tetracycline 32.3/22.1% (R 29.2/19.3%). There were only minor differences in resistance rates according to age, sample site, admission type (i.e. ambulatory, hospitalized or long-term care facility patients), gender and geographic origin. Overall, telithromycin (MIC50, MIC90 in 2003/2004: 0.015 microg/ml, 0.12 microg/ml/ 0.008,0.06 respectively), ertapenem (0.03; 0.25/NT), moxifloxacin (0.06; 0.25/0.06, 0.12), and amoxicillin +/- clavulanic acid (0.03; 0.25/0.015, 0.5) were the most active compounds in both surveys. In 2003, the most common resistance phenotype was isolated insusceptibility to tetracycline (10.5%) followed by combined insusceptibility to erythromycin and tetracycline (9.3%). Erythromycin-tetracycline resistance (10.4%) was the most common in 2004. Isolates showing resistance to an antibiotic were significantly more present in 2003 than in 2004 (50.4% versus 40.8%). In penicillin-insusceptible isolates, MICs of all beta-lactams were increased but cross-resistance between penicillin and other beta-lactams in the penicillin-insusceptible isolates was not complete. In the 2003 survey, most of these isolates remained fully susceptible to ertapenem (94.9%) and amoxicillin +/- clavulanic acid (83.1%). In the 2004 survey, 91.9% of the penicillin insusceptible isolates remained susceptible to amoxicillin +/- clavulanic acid. In both surveys, the most common serotypes in penicillin insusceptible isolates were 14, 23,19 and 9 (20.0%, 20.0%, 16.4% and 10.9% respectively in 2003; 41.6%, 11.7%, 15.0% and 18.3% respectively in 2004).

Surveillance of antibiotic resistance in clinical isolates of Streptococcus pneumoniae collected in Belgium during winter 2000-2001.

A total of 314 isolates of Streptococcus pneumoniae collected by 10 different laboratories were tested for their susceptibility by using a microdilution technique following NCCLS recommendations. The following antibiotics were included: penicillin, ampicillin, amoxicillin, amoxicillin/clavulanate, cefaclor, cefuroxime, cefotaxime, imipenem, ciprofloxacin, gemifloxacin, levofloxacin, erythromycin, clarithromycin, azithromycin, miocamycin, clindamycin and tetracycline. The insusceptibility rate (IR) to penicillin was 21.0% [10.8% intermediate (> or = 0.12-1 microgram/mL) and 10.2% high-level (> or = 2 micrograms/mL)], to cefotaxime 7.3% [3.5% intermediate (> or = 1 microgram/mL) and 3.8% high-level (> or = 2 micrograms/mL)], to imipenem 3.8% [3.8% intermediate (> or = 0.25-0.5 microgram/mL) and 0% high-level (> or = 1 microgram/mL)], to ciprofloxacin 11.2% [8.3% intermediate (2 micrograms/mL) and 3.9% high-level (> or = 4 micrograms/mL)], to erythromycin 30.3% [3.5% intermediate (0.5 microgram/mL) and 26.8% high-level (> or = 1 microgram/mL)] and to tetracycline 38.5% [0.9% intermediate (4 micrograms/mL) and 37.6% high-level (> or = 8 micrograms/mL)]. No decreased susceptibility was found for gemifloxacin (> or = 0.5 microgram/mL). This compound was the most active with MIC50, MIC90 and an IR of 0.015 microgram/mL, 0.03 microgram/mL and 0% respectively, followed by amoxicillin/clavulanate, amoxicillin and imipenem (MIC50, MIC90 and IR: 0.015 microgram/mL, 1 microgram/mL, 1.6%/0.015 microgram/mL, 1 microgram/mL, 1.9%/0.008 microgram/mL, 0.12 microgram/mL, 3.8% respectively). Compared to the 1999 surveillance, penicillin and tetracycline-insusceptibility increased with 4.9% and 15.6% respectively, while cefotaxime, erythromycin and ciprofloxacin insusceptibility decreased with 5.4%, 5.8% and 4.4% respectively. MICs of all beta-lactams rose with those of penicillin for penicillin-insusceptible isolates. Imipenem, cefotaxime, amoxicillin and amoxicillin/clavulanate were generally 4, 2, 1 and 1 doubling dilutions respectively more potent than penicillin on these isolates while ampicillin, cefuroxime and cefactor were generally 1, 2 and 4 dilutions respectively [table: see text] less potent. Most penicillin-insusceptible isolates remained fully susceptible to amoxicillin/clavulanate (92.4%), amoxicillin (90.9%) and imipenem (81.8%). Erythromycin-tetracycline insusceptibility was the most common resistance phenotype (14.3%). Three- and four-fold resistance was found in 12.4% and 1.6% respectively of the isolates. Most penicillin-insusceptible isolates were of capsular types 14 (22.7%), 23 (21.2%), 6 (18.2%), 9 (13.6%) and 19 (12.1%).

Study of the in vitro activity of amoxicillin/clavulanic acid and other beta-lactam antibiotics against Escherichia coli isolated from urine specimens.

A total of 205 serial, unduplicated urinary isolates of Escherichia coli was collected from June through August 1998 in 2 community and 3 hospital laboratories. By using the NCCLS broth microdilution technique, their in vitro susceptibility to ampicillin, amoxicillin/clavulanic acid, cefuroxime, cefuroxime axetil, ticarcillin/clavulanic acid and piperacillin/tazobactam was determined. One hundred and twenty isolates were from hospitalised patients, 85 from ambulatory, 129 community acquired and 76 nosocomial. Half of the nosocomial isolates were obtained from naturally produced and half from alternatively produced urine specimens. In general, the highest susceptibility rates, following NCCLS criteria, were found for piperacillin/tazobactam (93.2%) followed by cefuroxime (92.2%) and amoxicillin/clavulanic acid (82.9%). Ampicillin showed a clear bimodal distribution with a clear peak for the resistant population. The highest degree of ampicillin resistance was found in nosocomial isolates. Overall, ampicillin showed the lowest degree of susceptibility. Most of the ampicillin resistant isolates remained susceptible to piperacillin/tazobactam, cefuroxime and amoxicillin/clavulanic acid. In general, the community acquired isolates had higher susceptibility rates than the nosocomial isolates.

Comparative in vitro activity of temocillin and other antimicrobial agents against Enterobacteriaceae isolated from patients admitted to five Belgian hospitals.

Temocillin, a methoxy-derivative of the broad-spectrum penicillin, ticarcillin, has been introduced into clinical practice in Belgium in 1988. Since then, not many surveys of its in vitro activity have been published. This study addresses this issue in a prospective collection of 300 consecutive Gram-negative isolates originating from in-patients in five general hospitals throughout Belgium. In addition to temocillin, seven common antibiotics were tested: amoxicillin-clavulanate, piperacillin-tazobactam, cefotaxime, aztreonam, meropenem, ciprofloxacin and amikacin. Meropenem appeared to exhibit the best activity overall, whereas amoxicillin-clavulanate scored the worst. Cumulative MIC plot for two subsets of organisms are given: temocillin, meropenem and cefotaxime are the most active on E. coli and Klebsiella spp., while a significant percentage is resistant to ciprofloxacin and amoxicillin-clavulanate. In the group of inducible Enterobacteriaceae, temocillin, meropenem and amikacin are the most active drugs, while the activity of amoxicillin-clavulanate, piperacillin-tazobactam, cefotaxime and ciprofloxacin is largely decreased. Taking this well preserved in vitro activity of temocillin into account, and looking at its convenient pharmacokinetics and low cost of acquisition, this drug may prove a useful alternative in the treatment of severe nosocomial infections.