Reduction of vancomycin use in orthopedic patients with a history of antibiotic allergy

Antimicrobial prophylaxis in the surgical patient

The primary prophylactic measure against postoperative infection is antiseptic technique in patient preparation, during surgery, and in postoperative patient care. Antimicrobial prophylaxis against postoperative infection is not indicated for procedures with a low infection rate because the expected benefit of antimicrobial treatment is less than the risk of an adverse medication reaction. Antimicrobial prophylaxis has been demonstrated to be of greater benefit than risk in some procedures with higher infection rates; however, because the problem is complex and the data are limited, extra-polating these findings to the practitioner's setting and the individual patient remains a challenge (Table 1). Although antimicrobial prophylaxis for bacterial endocarditis is not effective for most patients, the seriousness of the potential infection has driven the creation of guidelines recommending prophylaxis for at-risk patients undergoing at-risk procedures. Applying these guidelines appropriately could help to reduce unwarranted use of antimicrobials. In the prophylactic use of antimicrobials, as in many medical interventions, the difficulty is balancing the risks of the intervention with the potential benefits. Although we do not have either the randomized, controlled trials or the detailed, patient-specific information to estimate this balance precisely, there are general guidelines to help the clinician choose treatment for most patients.

Preventing and managing drug-induced anaphylaxis

Drug-induced anaphylaxis and anaphylactoid reactions have increased in frequency with more widespread use of pharmaceutical agents. Anaphylaxis is a systemic, severe immediate hypersensitivity reaction caused by immunoglobulin (Ig) E-mediated immunological release of mediators of mast cells and basophils. An anaphylactoid reaction is an event similar to anaphylaxis but is not mediated by IgE. The incidence of anaphylactic or anaphylactoid reactions differs amongst classes of medications. Antibacterials are the most usual offenders, and penicillins are the most studied. Other compounds commonly causing reactions include non-steroidal anti-inflammatory drugs, anaesthetics, muscle relaxants, latex and radiocontrast media. Prevention, if possible, is the purpose of detailed patient history taking and physical examination. Simple strategies can be employed to decrease the risk of anaphylaxis. These include consideration of the route of drug administration, identification of patients with known causes of anaphylaxis, and the knowledge that certain medications cross react and are contraindicated in those with known history of anaphylaxis. Tests are available, and include IgE-specific skin tests and radioallergosorbent tests. Penicillins are the only compounds whose antigenic determinants are well documented, it is therefore difficult to determine the negative predictive value of other compounds tested. Oral challenge remains an alternative, though entails risk. Desensitisation procedures, as well as gradual dose escalation protocols, are available and can be implemented based on patient history and diagnostic testing. The management of anaphylaxis is based on control of the airway, breathing and circulation. Treatment consists of epinephrine (adrenaline) and supportive measures. Rapid diagnosis and intervention are important in these life-threatening reactions. After stabilisation, all individuals with a documented history of anaphylaxis require a Medic-Alert bracelet or necklace, and an identification card for their wallet or purse.