Penicillin skin reactions

In penicillin-allergic patients, oral or parenteral clindamycin may be used. Alternatively, a first-generation cephalosporin such as cefazolin (1 to 2 g IV every 6 to 8 hours) may be used cautiously for patients who have not experienced immediate or anaphylactic penicillin reactions and are penicillin skin test negative. In severe cases in which cephalosporins cannot be used because of documented methicillin resistance or severe allergic reactions to /1-lactam antibiotics, IV vancomycin should be administered. 

The incidence of nonallergic ampicillin eruptions is 40 to 100% in patients with concomitant Epstein-Barr virus (mononucleosis), cytomegalovirus, acute lymphocytic leukemia, lymphoma, or reticulosarcoma. Nonallergic penicillin-associated rashes are characteristically morbilliform (symmetrical, erythematous, confluent, maculopapular) eruptions on the extremities. The onset of typical nonallergic eruptions is more than 72 hours after (3-lactam exposure. The mechanism for the nonurticarial ampicillin rash is not known and is not related to IgE or type I hypersensitivity. Penicillin skin tests are not useful in the evaluation of nonurticarial ampicillin rashes. Patients with a history of nonurticarial ampicillin rashes may receive other (3-lactam antibiotics without greater risk of subsequent serious allergic reactions. 

The cephalosporins are contraindicated in patients with known allergies or intolerances to any of the cephalosporins. Because the penicillins and cephalosporins have a common chemical structure, cross-allergies occur with these drugs. Thus before initiating therapy with a cephalosporin, careful inquiry should be made concerning previous hypersensitivity reactions to the other drugs. Because a secondary vitamin K deficiency can develop with cephalosporin use, the cephalosporins are contraindicated in patients with hemophilia. Cefaclor is also contraindicated in any patient with previous drug-related joint and skin reactions. 

There was a high degree of cross-reactivity between imipenem determinants, analogous to the penicillin determinants in penicillin-allergic patients. Nine of twenty patients with positive penicillin skin tests had positive skin reactions to analogous imipenem determinants (40). In view of this appreciable cross-reactivity, imipenem should not be given to patients with penicillin allergy. 

Skin rashes are relatively common with flnoroqninolones. A retrospective cohort stndy in patients in general practice in the Netherlands focused on the nse of antibacterial agents and the occnrrence of adverse cntaneons events covered 469 505 consnltations with 87 475 patients, of whom 13 679 received prescriptions for antibiotics (57). After adjnstment for age, sex, and co-medications, the incidence density ratio (incidence density per 1000 exposed days) for varions gronps of antibacterial agents was as follows tetracyclines 1.0, macrohdes 1.1, flnoroqninolones 2.8, penicillins 2.9, and co-trimoxazole 4.4 (57). No details of the types of skin reactions were given, and it is therefore possible that phototoxic events were inclnded. Compared with other stndies, the reported rate of antibiotic-associated adverse cntaneons events in this ontpatient popnlation was rather low. 

Skin reactions are the commonest adverse effects of therapeutically administered penicillins (120). PeniciUin-contaminated milk or meat can cause itching or generalized skin reactions (121) or even anaphylaxis (122,123). 

In contrast to other drugs, penicillin-induced skin reactions can occur after more than 1 week of therapy (60). The typical presentation is a maculopapular, erythematous, symmetrically disposed rash on the legs, buttocks, and trunk. 

Penicillins should be avoided in any patient who gives a history of a skin reaction or anaphylaxis to any penicillin derivative. To prevent mild skin reactions becoming severe when they occur, it is advisable to withdraw the culprit antibiotic not only when a type I reaction is suspected but in aU kinds of common rashes, in view of a possible epider-moljdic process. A diet free of dairy products was curative in 30 of 70 patients with positive tests (170). 

Patients with a history of a reaction to penicillin are advised not to receive cephalosporins if they can be avoided. Patients who have negative penicillin skin tests or experienced only mild cutaneous reactions, such as macu-lopapular rashes, have a low risk of serious reactions to cephalosporins. 

Immediate hypersensitivity reactions to penicillin are rare after a properly performed negative skin test when both major and minor determinants are used. Dermatologic reactions occur in 1% of skin-test-negative patients. A negative penicillin skin test indicates... 

Patients with delayed reactions to penicillin (skin rash) generally can receive cephalosporins. Patients with type I hypersensitivity reactions to penicillins (anaphylaxis) should not receive cephalosporins or carbapenems (alternatives include aztreonam, quinolones, sulfa drugs, or vancomycin based on type of coverage indicated). 

If a patient has a mild, delayed allergy to penicillin, first-generation cephalosporins (such as cefazolin) are effective alternatives, but they should be avoided in patients with a history of immediate-type hypersensitivity reactions to penicillins (see Table 109-6). The potential for a true immediate-type allergy should be assessed carefully, and a penicillin skin test should be conducted before giving antibiotic treatment to any patient claiming an allergy. 

The polymers isolated from ampicillin and benzylpenicillin solutions have further been shown to give wheal and flare reactions in a number of penicillin allergic patients, all of whom have given skin reactions also to a penicilloyl-polylysine conjugate (JuHLiN et al. 1977). Finally, a limited clinical study by Parker and Richmond (1976) has indicated that the use of so-called polymer-free ampicillin may reduce the incidence of certain exanthematic adverse reactions to ampicillin preparations. 

Solley O, Gleich J, Jordan RE, Schroeter AL (1976) The late phase of the immediate wheal-and-flare skin reaction. Its dependence upon IgE antibodies. J Clin Invest 58 408 Spark RP (1971) Fatal anaphylaxis due to oral penicillin. Clin Pathol 56 407 Spengler H, de Week AL (1977) Evaluation of genetic control of the immune response to penicillin in man. Monogr Allergy 11 116... 

Table 1. Skin reactions to various determinants in penicillin allergy in patients with a history of penicillin allergy...

Furthermore, some measures may be visualized to prevent polymer formation in benzylpenicillin solutions. Indeed, it was shown that polymers and even small oligomers are capable of eliciting skin reactions in penicillin-sensitive individuals (Batchelor et al. 1967 de Weck et al. 1968) and are also capable of eliciting PCA reactions in guinea pigs passively sensitized with IgE-like anti-BPO antibodies (Muranaka et al. 1974,1978 de Weck 1976 de Weck et al. to be published Koizumi et al. 1980 Igarashi et al. 1978). 

Immunologic Of 85 patients with a history of penicillin allergy and positive penicillin skin tests 5 (6%) had an adverse drug reaction to a cephalosporin compared with 5 (0.7%) of 726 patients with a history of penicillin allergy but negative penidllin skin tests [7. Presumed IgE-mediated adverse reactions to the cephalosporins occurred in 2 (2%) of the former compared with only 1 (0.1%) of the latter. 

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