Final answer:
Streptomycin is an effective alternative for treating gram-negative rod infections in patients allergic to penicillins or cephalosporins. Aminoglycosides like gentamicin, tetracyclines, or sometimes carbapenems may also be used, depending on the specific pathogen's susceptibility.
Step-by-step explanation:
A useful alternative to treating gram-negative rod infections in patients allergic to penicillins or cephalosporins is the antibiotic streptomycin. Streptomycin is effective against a broad range of gram-negative bacteria and works by binding to the 30S ribosome, which inhibits protein synthesis, leading to the death of the bacterial cell. Another alternative for patients with penicillin or cephalosporin allergies is the use of aminoglycosides, such as gentamicin, or tetracyclines. However, these antibiotics should be chosen based on the susceptibility of the specific pathogen involved. Patients with severe infections may require treatments with carbapenems, which are effective against extended-spectrum ß-lactamase-producing pathogens, although these are usually reserved for multidrug-resistant infections due to their broad spectrum of activity.