penicillin allergy

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penicillin allergy

A hypersensitivity reaction to penicillin, present in about 0.5% to 8% of the population. Although different types of hypersensitivity reactions may occur, the most common and potentially dangerous are the type I (immediate) reactions mediated by immunoglobulin E. If a patient reports a history of signs of local anaphylaxis (such as urticaria) or systemic anaphylaxis (such as bronchoconstriction, vasodilation) after taking penicillin, no penicillin or other beta-lactam antibiotics (such as cephalosporins) should be given to that patient ever again. In those very rare situations in which an infection is susceptible to no other antibiotic and the infection is serious enough to risk the danger of anaphylaxis, the patient may be desensitized with gradually increasing doses of penicillin.
See also: allergy


any of a large group of natural or semisynthetic antibacterial antibiotics derived directly or indirectly from strains of fungi of the genus Penicillium and other soil-inhabiting fungi grown on special culture media. Penicillins exert a bactericidal as well as a bacteriostatic effect on susceptible bacteria by interfering with the final stages of the synthesis of peptidoglycan, a substance in the bacterial cell wall. Despite their relatively low toxicity for the host, they are active against many bacteria, especially gram-positive pathogens (streptococci, staphylococci); clostridia; certain gram-negative forms; certain spirochetes (Treponema pallidum and T. pertenue); and certain fungi. Certain strains of some target species, for example staphylococci, secrete the enzyme penicillinase, which inactivates penicillin and confers resistance to the antibiotic. Some of the newer penicillins, for example methicillin, are more effective against penicillinase-producing organisms. An additional class of extended-spectrum penicillins has been approved for use; it includes piperacillin and mezlocillin.
There are four groups of penicillins, the natural penicillins, penicillin G and penicillin V, with a narrow spectrum of activity, mainly against gram-positive bacteria; the aminopenicillins (amoxicillin, ampicillin and hetacillin) are semisynthetic derivatives and have a broad spectrum of activity against gram-positive and many gram-negative organisms, but are susceptible to penicillinase-producing Staphylococcus spp.; penicillinase-resistant penicillins, which include cloxacillin, methicillin, nafcillin and oxacillin; and the extended-spectrum penicillins (azlocillin, carbenicillin, mezlocillin, piperacillin and ticarcillin), which are effective against gram-positive and gram-negative organisms, including Pseudomonas aeruginosa.
Allergic reaction to penicillin occurs in some animals. The reaction may be slight—a stinging or burning sensation at the site of injection—or it can be more serious—severe dermatitis or even anaphylactic shock, which may be fatal.

penicillin allergy
degradation products of the penicillins act as haptens, binding to proteins and stimulating an immune response.
penicillin G
benzylpenicillin; the most widely used penicillin; used principally in the treatment of infections due to gram-positive bacteria. Procaine penicillin G is a parenteral preparation that gives extended action for up to 24 hours and benzathine penicillin G is a very slow-release, parenteral preparation that maintains blood levels for several days.
penicillin-induced hemolytic anemia
rare problem in horses which develop IgG anti-penicillin antibodies.
phenoxymethyl penicillin
a biosynthetically or semisynthetically produced antibiotic, similar to penicillin G, for oral administration; not affected by gastric acid and is suitable for oral administration. Its antibacterial spectrum is the same as for penicillin G. Called also penicillin V.
penicillin V
see phenoxymethyl penicillin (above).
References in periodicals archive ?
Penicillin allergy testing is becoming recognized as an important part of an effective antibiotic stewardship program," says Eric Macy, MD, Kaiser Permanente, San Diego.
But this appears to be due to overall increased reactiveness and not a cross-reactivity, because those with history of penicillin allergy had an even higher allergy rate to sulfa nonantibiotics than did patients with a prior sulfa allergy.
There is also a "traffic-light" system identifying which antibiotics should not be given to patients with penicillin allergy.
Recommend that cefazolin be used for prophylaxis in those who have a nonsevere penicillin allergy.
Penicillin allergy is an interesting case since it is capable of eliciting both Type) and IV Gell-Coombs hypersensitivities.
The study suggested incorporating a 30-minute penicillin skin test protocol as standard procedure for emergency patients reporting a penicillin allergy.
Other victims of Stafford Hospital's failures include 77 year-old Cannock pensioner Lillian Tucker, who had a known penicillin allergy when she was admitted to the hospital with a fractured pelvis in October 2005 but was wrongly injected with a penicillin-based drug.
It was subsequently elucidated that she had a history of penicillin allergy.
Even though penicillin allergy was noted in her medical files by Dr Kevin Owens, he was so busy that he forgot, and prescribed the pensioner an antibiotic containing penicillin, Cannock coroner's court heard yesterday.
We noticed a seemingly high prevalence of penicillin allergy in patients who had been diagnosed with peritonsillar abscess (PTA) at our institution.
At the scene an attendant scans the patient's medic alert bracelet that indicates a penicillin allergy.