Screening for β-lactam resistance by penicillin G in the Streptococcus anginosus group challenged by rare strains with altered PBPs.

Our study suggests that aminopenicillin and third-generation cephalosporin susceptibility should be determined for SAG strains in the event of severe infection as screening for penicillin G resistance might not be sufficient to detect resistance mechanisms that predominantly affect cephalosporins. The PBP sequencing of resistant SAG strains allowed us to detect amino acid changes potentially linked to β-lactam resistance.