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A total of 6,991 unique patient isolates of Streptococcus pneumoniae were collected from October 1997 to June 2002 from 25 medical centers in 9 of the 10 Canadian provinces. Among these isolates, 20.2% were penicillin nonsusceptible, with 14.6% being penicillin intermediate (MIC, 0.12 to 1 g/ml) and 5.6% being penicillin resistant (MIC, >2 g/ml). The proportion of high-level penicillin-resistant S. pneumoniae isolates increased from 2.4 to 13.8% over the last 3 years of the study, and the proportion of multidrug-resistant S. pneumoniae isolates increased from 2.7 to 8.

VRE urinary isolates are common in the United States, are primarily of the vanA genotype and are very susceptible to linezolid, nitrofurantoin and chloramphenicol. In Canada, VRE urinary isolates remain uncommon.

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A total of 7,566 unique patient isolates of Haemophilus influenzae and 2,314 unique patient isolates of Moraxella catarrhalis were collected between October 1997 and June 2002 from 25 medical centers in 9 of the 10 Canadian provinces. Among the 7,566 H. influenzae isolates, 22.5% produced ␤-lactamase, while 92.4% of the 2,314 M. catarrhalis isolates produced ␤-lactamase. The incidence of ␤-lactamase-producing H. influenzae isolates decreased significantly over the 5-year study period, from 24.2% in 1997-1998 to 18.6% in 2001-2002 (P < 0.01). The incidence of ␤-lactamase-producing M. catarrhalis isolates did not change over the study period. The overall rates of resistance to amoxicillin and amoxicillin-clavulanate for H. influenzae were 19.3 and 0.1%, respectively. The rank order of cephalosporin activity based on the MICs at which 90% of isolates were inhibited (MIC 90 s) was cefotaxime > cefixime > cefuroxime > cefprozil > cefaclor. On the basis of the MICs, azithromycin was more active than clarithromycin (14-OH clarithromycin was not tested); however, on the basis of the NCCLS breakpoints, resistance rates were 2.1 and 1.6%, respectively. Rates of resistance to other agents were as follows: doxycycline, 1.5%; trimethoprim-sulfamethoxazole, 14.2%; and chloramphenicol, 0.2%. All fluoroquinolones tested, including the investigational fluoroquinolones BMS284756 (garenoxacin) and ABT-492, displayed potent activities against H. influenzae, with MIC 90 s of <0.03 g/ml. The MIC 90 s of the investigational ketolides telithromycin and ABT-773 were 2 and 4 g/ml, respectively, and the MIC 90 of the investigational glycylcycline GAR-936 (tigecycline) was 4 g/ml. Among the M. catarrhalis isolates tested, the resistance rates derived by using the NCCLS breakpoint criteria for H. influenzae were <1% for all antibiotics tested except trimethoprim-sulfamethoxazole (1.5%). In summary, the incidence of ␤-lactamase-positive H. Haemophilus influenzae and Moraxella catarrhalis are recognized as important causes of community-acquired respiratory infections, including community-acquired pneumonia, acute exacerbations of chronic bronchitis, acute sinusitis, and acute otitis media (1,5,9,13,14,22). Due to the extensive use of the protein-conjugated type b capsular polysaccharide vaccine in developed countries, H. influenzae infections are caused by nontype b strains (7,8,10,23). As community-acquired respiratory tract infections are treated empirically (with no knowledge of the antibiotic susceptibilities of a specific isolate from a patient), knowledge of present and local resistance rates is essential in determining effective therapy (1, 14). Ongoing systematic surveillance studies provide clinicians with knowledge of these resistance rates, allowing determination of the optimal treatment.In a study conducted in 1997 and 1998 (23), we described the prevalences of ␤-lactamase-producing H. influenzae and M. catarrhalis isolates to be 24.0 and 94.2%, respectively. The present report describes the results of an ongoing annual study, the...

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180 respiratory tract isolates of Streptococcus pneumoniae were collected from 18 medical centers in 9 of the 10 Canadian provinces. Penicillin-intermediate and -resistant isolates occurred at rates of 14.8 and 6.4%, respectively, and these rates varied considerably by geographic region. Trimethoprim-sulfamethoxazole, tetracycline, and macrolide rates of nonsusceptibility were 12.2, 10.6, and 8.0 to 9.3%, respectively. The most potent agents studied were newer fluoroquinolones.

The in-vitro activity of RP 59500 and comparative agents was determined against 270 clinical isolates of the genus Staphylococcus. MICs were performed by micro-dilution dilution. MIC90 and MBC90 (mg/L) of RP 59500 were as follows: oxacillin-sensitive Staphylococcus aureus (0.5/0.5), oxacillin-resistant S. aureus (0.5/0.5), oxacillin-sensitive Staphylococcus epidermidis (0.5/0.5), oxacillin-resistant S. epidermidis (0.25/0.25), oxacillin-resistant Staphylococcus hominis (1.0/1.0), oxacillin-resistant Staphylococcus haemolyticus (1.0/1.0), oxacillin-sensitive Staphylococcus saprophyticus (1.0/1.0). Killing kinetic methods were used to assess the bactericidal activity of inhibitory (1 x, 2 x MIC) concentrations of RP 59500 in comparison with that of vancomycin (1 x, 2 x MIC) and oxacillin (1 x, 2 x MIC) against 20 strains of oxacillin-sensitive and -resistant S. aureus and S. epidermidis. RP 59500 was as active as vancomycin, displaying rapid bactericidal activity against the majority of strains tested and reducing initial inoculum counts by greater than 99.9% in 2-12 h. Regrowth was seen with some S. epidermidis strains after 12-24 h.