Hypersensitivity to penicillin

A hypersensitivity (or allergic) reaction to a drug occurs in some individuals, especially those with a history of allergy to many substances. Signs and symptoms of a hypersensitivity to penicillin are highlighted in Display 7-3. 

Penicillins are contraindicated in patients witii a history of hypersensitivity to penicillin or die cephalosporins. 

FIGURE 69-3. Treatment algorithm3 for acute bacterial rhinosinusitis in patients with mild disease without recent antibiotic exposure.31 aAntibiotics are listed in order of predicted efficacy based on predicted clinical and bacteriologic efficacy rates, clinical studies, safety, and tolerability. Doses can be found in Table 69-4. 6Cephalosporins should be considered for patients with non-type I hypersensitivity to penicillins they are more likely to be effective than the alternative agents. cHigh doses (90 mg/kg per day) are recommended for most children, especially those with day-care contacts or frequent infections. 

For penicillin-allergic (nonanaphylactoid type) patients cefazolin 6 g/24 hours IV in 3 equally divided doses 6 IB Consider skin testing for oxacillin-susceptible staphylococci and questionable history of immediate-type hypersensitivity to penicillin cephalosporins should be avoided in patients with anaphylactoid-type hypersensitivity to P-lactams vancomycin should be used in these cases ... 

In a patient with a positive penicillin skin test or a history of immediate hypersensitivity to penicillin, vancomycin is the agent of choice. Vancomycin, however, kills S. aureus slowly and is generally regarded as inferior to penicillinase-resistant penicillins for MSSA. Penicillin-allergic patients who fail on vancomycin therapy should be considered for penicillin desensitization. 

A patient who is taking phenytoin and is hypersensitive to penicillin requires a broad-spectrum antibacterial agent for a respiratory tract infection. 

Sulfadiazine and sulfisoxazole still play a useful role in the prophylaxis of group A streptococcal infections in patients with rheumatic fever who are hypersensitive to penicillin. This is tempered with the potential for toxicity and infection with resistant Streptococcus pyogenes. 

Contraindications Hist ory of seizures or CNS abnormality, hypersensitivity to penicillins. 

Aztreonam Prevents bacterial cell wall synthesis by binding to and inhibiting cell wall transpeptidases Rapid bactericidal activity against susceptible bacteria Infections caused by aerobic, gram-negative bacteria in patients with immediate hypersensitivity to penicillins IV administration renal clearance half-life 1.5 h dosed every 8 h Toxicity No cross-allergenicity with penicillins... 

One of the primary problems with penicillin drugs is the potential for allergic reactions.65 Hypersensitivity to penicillin is exhibited by skin rashes, hives, itching, and difficult breathing. In some individuals, these reactions may be minor and can often be resolved by changing the type of penicillin or the method of administration. In others, however, penicillin hypersensitivity may be severe and lead to an anaphylactic reaction (severe bronchoconstriction and cardiovascular collapse). 

C. Cefoxitin is less likely to cause an allergic reaction in a patient that is hypersensitive to penicillin G than is penicillin V. 

Alternative treatment for cellulitis in a patient hypersensitive to penicillins is the macrolide erythromycin. 

Cephalosporins should be avoided in patients with immediate type hypersensitivity to penicillin... 

In a patient with a positive skin test or a history of immediate hypersensitivity to penicillin, vancomycin is the agent of choice. Vancomycin, however, kills S. aureus slowly and is regarded as inferior to penicillinase-resistant penicillins for MSSA. Rifampin as an adjunctive therapy is controversial however, this agent, added to vancomycin in refractory or complicated infections in patients with left-sided IE may result in dramatic patient improvement. Generally, antibiotic therapy should be continued for 4 to 6 weeks. Unfortunately, left-sided IE caused by S. aureus continues to have a poor prognosis, with a mortality rate of 25% to 47%. Eor reasons discussed in the following section, those with IE associated with TVDA have a more favorable response to therapy. 

Dodek P, Phillip P. Questionable history of immediate-type hypersensitivity to penicillin in staphylococcal endocarditis Treatment based on skin test results versus empirical alternative treatment—A decision analysis. Clin Infect Dis 1999 29 1251-1256. 

The sulfonamides are as efficacious as oral penicillin in preventing streptococcal infections and recurrence of rheumatic fever in susceptible subjects and are used in patients who are hypersensitive to penicillin. Untoward responses usually occur during the first 8 weeks serious reactions after this time are rare. White blood cell counts should be checked weekly during the first 8 weeks. 

Resistance to sulfonamides is now common for N. meningitidiSy as well as in cases of bacillary dysentery. Antibiotics have generally replaced the sulfonamides for these purposes. Sulfonamides, particulady sulfisoxazole and sulfadiazine, are of value in treatment of infections due to Nocardia species, and sulfonamides are effective for trachoma. Inclusion conjunctivitis is also treated with sulfacetamide ointment. Oral administration of a sulfonamide, eg, sulfisoxazole, has been successful for treatment of lymphogranuloma venereum and chancroid Dapsone and sulfonamides have also been used for treatment of the skin disorder dermatitis herpetiformis. Sulfonamides have been used for long term prophylaxis of rheumatic fever, but are being replaced by penicillin for this purpose, except in cases of hypersensitivity to penicillin (19). 

Spectinomycin (2 g intramuscularly) is the appropriate choice in this case. Avoid cephalosporins in patients with a history of severe hypersensitivity to penicillins, and avoid fluoroquinolones (see Chapter 46) in pregnancy. Tetracyclines have been used in the past for gonorrhea but not as single doses, and they too should be avoided in pregnancy. The answer is (D). 

We have tested this method in investigating 18 patients with a known hypersensitivity to penicillin by clinical and laboratory criteria, and have compared it with other procedures, i.e., skin tests and penicillin RAST. Clinically, all the patients could be classified as showing type I reactions. Six patients were excluded from the study, owing to an insufficiant number of basophils, rendering the test not feasible. 

Adkinson NF (1975) Recent developments in the use of RAST for determining hypersensitivity to penicillin. In Evans E (ed) Advances in diagnosis of allergy. RAST, Miami... 

Undeniably, there are a number of patients with exanthema in whom all investigations, including skin, serological, and cellular tests, fail to detect hypersensitivity to penicillins. In such patients, the pathogenesis of the skin lesions remain mysterious. The possibility that interaction between ampicillin and lymphocytes may under some circumstances promote the formation and release of lymphokines is no more than a working hypothesis. 

Fellner MJ, Baer RL, Ripps CS, Hirschom K (1967 a) Response of lymphocytes to penidllin comparison with skin tests and drculating antibodies in man. Nature 216 803 Fellner MJ, Redmond AP, Levine BB, Baer RL (1967 b) Immediate penidllin reactions associated with penicilloyl-specific skin-sensitizing antibodies and low titers of blocking (IgG) antibodies. J Allergy Clin Immunol 38 106 Fellner MJ, Ball EH, Allyn B, Baer RL (1969) Delayed hypersensitivity to penicillin. JAMA 210 2061... 

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