Activities of New Fluoroquinolones, Ketolides, and Other Antimicrobials against Blood Culture Isolates of Viridans Group Streptococci from across Canada, 2000

Abstract

The rates of nonsusceptibility to penicillin, erythromycin, and clindamycin of 191 blood culture isolates of viridans group streptococci collected from across Canada in 2000 were 36, 42, and 10%, respectively. Although 8% of the strains were resistant to ciprofloxacin (MIC 4 g/ml), the MICs of gemifloxacin, BMS 284756, telithromycin, and ABT 773 at which 90% of the strains were inhibited were 0.06, 0.06, 0.12, and 0.03 g/ml, respectively.

Antimicrobial Susceptibility Patterns among Viridans Group Streptococcal Isolates from Infective Endocarditis Patients from 1971 to 1986 and 1994 to 2002

“…In the same studies, MIC 90 s of gatifloxacin (0.25 to 0.5 g/ml), moxifloxacin (0.25 g/ml), and garenoxacin (0.06 g/ml) were comparable to ours (Table 1) (6,7,12). In contrast, the level of penicillin nonsusceptibility among the 1994 to 2002 isolates (13%) was lower than the 28 to 56% level reported in recent surveillance blood culture studies (6-8, 12, 13, 22, 28).…”

“…Among 1994 to 2002 isolates, higher MIC 90 s were found for ciprofloxacin (8 g/ml) and levofloxacin (8 g/ml) compared with other studies, wherein MIC 90 s ranged from 2 to Ն4 g/ml for ciprofloxacin and 1 to 2 g/ml for levofloxacin (6,7,12). In the same studies, MIC 90 s of gatifloxacin (0.25 to 0.5 g/ml), moxifloxacin (0.25 g/ml), and garenoxacin (0.06 g/ml) were comparable to ours (Table 1) (6,7,12).…”

In Vitro Activity of Telithromycin against Viridans Group Streptococci and Streptococcus bovis Isolated from Blood: Antimicrobial Susceptibility Patterns in Different Groups of Species

“…Moreover, of the 13 highly penicillin-resistant strains, 12 belonged to the S. mitis group and one belonged to the S. salivarius group. These results agree with other surveys which report that penicillin resistance is more common in S. mitis and S. salivarius than in S. anginosus (1,7,8).The resistance percentages for erythromycin and clindamycin were 45.6 and 27.7%, respectively. High percentages (30 to 50%) of erythromycin resistance have been reported in recent studies of VGS isolated from blood cultures (1, 5-7).…”

“…Most studies of VGS report that Streptococcus mitis, in addition to being the most frequently isolated group, is also the group that shows the highest rates of penicillin resistance (1,7,8,10,17). However, reports about the susceptibility of other VGS and S. bovis are scarce.…”

“…These organisms are also agents of endocarditis. Bacteremia caused by S. bovis isolates is associated with malignancies of the gastrointestinal tract.Recent studies have shown that VGS are becoming increasingly resistant to many antibiotics, and it seems that antimicrobial resistance is not homogeneous among the different members of the group (1,7,8,20). Most studies of VGS report that Streptococcus mitis, in addition to being the most frequently isolated group, is also the group that shows the highest rates of penicillin resistance (1,7,8,10,17).…”