Rat bite fever caused by Streptobacillus moniliformis presenting in a patient who carries a documented penicillin allergy. This allergy status rules out first-choice penicillin-class therapy and requires a specifically adapted treatment approach.
A history of penicillin allergy substantially narrows the antibiotic options for rat bite fever. Standard penicillin-based regimens cannot be used, and certain alternative agents have been associated with treatment failures in this population — making careful agent selection critical.
In penicillin-allergic patients, the regimen draws on alternative antibiotic classes — including aminoglycosides and tetracyclines — as primary options. The full selection criteria, any role for additional agent classes, and the complete clinical algorithm are in the structured protocol →
DOI: 10.1128/CMR.00016-06
For penicillin-allergic patients, both streptomycin and tetracycline appear to be effective, but erythromycin use has been associated with treatment failures.
Cephalosporins have also been used successfully and may be considered if cross-allergenicity with penicillin is felt to be unlikely.
View source ↗