Emergence of Resistance

Emergence of resistance on appropriate therapy is uncommon, occurring in 5–10% of infections treated.

Emergence of resistance to beta-lactams while on therapy with these agents occurs in ~20% of patients infected with organisms with inducible beta-lactamases: Serratia, Enterobacter, Citrobacter, Acinetobacter, Providencia, Morganella and Proteus (vulgaris,penneri).

Carbapenems are recommended initial therapy until susceptibility results available; other Beta-lactams are best avoided in these patients if other options are available.

ID consultation recommended for sterile site infection (blood/tissue/CSF) with these organisms

NOTE: Acinetobacter spp. are resistant to ertapenem

Emergence of resistance is more common in pneumonia and osteomyelitis due to decreased antibiotic penetration at these sites; attention should be given to appropriate dosing in these patients.

The addition of additional agents may lead to increased toxicity from adverse drug reactions without preventing emergence of resistance.