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WHAT ARE THE ALTERNATIVES TO PENICILLIN?

Dr. Marvin Turck looks at penicillin allergy and alternatives to penicillin for the penicillin-sensitive patient.

While prediction of penicillin hypersensitivity based upon patient history or positive PPL skin test is useful, adherence to

these findings may exclude from treatment patients who might benefit from penicillin therapy without experiencing any

untoward effects. Therefore, in patients with serious infections, such as enterococcal or staphylococcal bacterial

endocarditis, the use of penicillins is not contraindicated. On the other hand, if the patient has a less severe illness, an

alternative antibiotic should be used.

Desensitisation to penicillin has not been properly evaluated due to the small number of patients treated and the

underlying unpredictability of penicillin allergy. 'It is our feeling that the practices of attempting to decrease the frequency of allergic reactions in patients hypersensitive to penicillin by desensitization, antihistamines, or corticosteroids are of dubious value and should be deplored, except in the occasional patients for whom no adequate alternative antimicrobials are available.'

Cross-allergy among the penicillins can be a problem. A patient allergic to penicillin G tends to also react to other

penicillins, although not necessarily to the same degree. The question of whether a patient allergic to penicillin will also

react to the cephalosporins remains to be resolved. 'In this article, cephalosporins are discussed as alternative antimi­crobials for patients sensitive to penicillin, but it Should be emphasized that the magnitude and severity of the problem remains to be defined. But clinical experience over a 1 0-year period has demonstrated that a majority of patients with a history of penicillin allergy can be given cephalosporins without risk of serious reaction.'

Alternatives to penicillin For the majority of minor staphylococcal infections acquired outside hospital, erythromycin or one of its congeners is a

satisfactory alternative to penicillin. More recently, clindamycin and lincomycin have been shown to be effective in

staphylococcal infections. While tetracyclines have also been used in staph infections, a high percentage of strains are

resistant to these antibiotics, and resistant strains may emerge during the course of therapy. Most coagulase-positive

staphylococci are sensitive to cephalexin.

More severe staphylococcal infections require treatment with vancomycin or a cephalosporin. Because of difficulties

associated with vancomycin administration, the cephalosporins have become the preferred agents in this area. In

staphylococcal enterocolitis, erythromycin, neomycin, kanamycin, or vancomycin may be used instead of penicillin.

In chronic osteomyelitis, lincomycin and clindamycin are particularly effective because of their affinity for bone.

Although penicillin G is still the most dependable agent for treatment of pneumococcal infections, there are several

effective alternatives: erythromycin, clindamycin, chloramphenicol, and the cephalosporins. In most cases, erythromycin

is an excellent alternative to penicillin, but its use is limited by the lack of an injectable preparation free of discomfort

and irritation. Reports of tetracycline resistance and treatment failures indicate that this agent not be used. Since there

are equally effective alternatives and because there is a risk of bone marrow depression, chloramphenicol should not be

used in patients with pneumococcal pneumonia; this is not the case, however, in pneumococcal meningitis.

Alternatives for the treatment of Group A streptococcal infections include erythromycin, clindamycin and cephalexin.

Tetracycline is inferior to these agents. In severe Group A streptococcal infections, a parenteral cephalosporin is adequate.

In bacterial endocarditis: 'The penicillins are superior to all antimicrobials in the treatment of endocarditis caused by penicillin-sensitive organisms. Experience with other antibiotics is quite limited, and guidelines for alternative therapy are poorly defined. In this situation, disk diffusion sensitivity tests must not be used to select alternative therapy. The alternative drug should be bactericidal at blood levels which can be readily achieved in vivo, and ideally the bactericidal activity of the serum should be measured during therapy.'

Turck, M.: Drug Therapy 1: 8 (May 197 6)

I NPHARMA 3rd July, 1976 p2