Should results for an extended-spectrum cephalosporin be reported for viridans group streptococci?
The decision to test and report extended-spectrum cephalosporins for isolates of viridans group streptococci that are not susceptible to penicillin depends on your institution. There is a comment in M100-S12 (Table 2H, comment 6, on page 114) that indicates penicillin-susceptible streptococci can be considered susceptible to other beta-lactam drugs. Consequently, penicillin-susceptible viridans group streptococci are considered susceptible to extended-spectrum cephalosporins (e.g., ceftriaxone). However, for isolates that are not penicillin susceptible (i.e., penicillin MICs >0.12 ug/ml), the extended-spectrum cephalosporin of interest should be tested. Viridans group streptococci that are not penicillin susceptible are often less susceptible to other beta-lactams as well. Question 8: Are the tests for high-level aminoglycoside resistance that are used to predict the synergy of aminoglycosides and cell wall-active agents for enterococci valid for viridans group streptococci? No. There
