The prevention of periprosthetic joint infection (PJI) relies fundamentally on the judicious administration of perioperative antibiotics. Cefazolin remains the evidence-based first-line agent for infection prophylaxis in total hip arthroplasty (THA) or total knee arthroplasty (TKA). Despite robust immunological and pharmacological evidence supporting its safety profile, cefazolin is often withheld from patients with documented β-lactam or cephalosporin allergies, a practice that persists contrary to current scientific consensus regarding cross-reactivity mechanisms. In an investigation at the Hospital for Special Surgery, Jolissaint et al. systematically assessed cefazolin use in patients noted to be allergic to cephalosporin. Prior analyses have predominantly addressed penicillin-allergic cohorts; this study distinguishes itself by focusing on patients with cephalosporin allergies, a population assumed to be at greatest risk for immunologically mediated adverse events. From a data set comprising 89,993 lower-extremity arthroplasty cases, 1,268 individuals (1.4%) were noted to have a cephalosporin allergy. Of these patients, 481 were administered cefazolin, at the discretion of the attending surgeon. Notably, no immunoglobulin-E-mediated hypersensitivity or severe delayed hypersensitivity reactions were observed in this group. In contrast, all 4 recorded allergic reactions occurred in patients who received vancomycin. These findings reinforce the mechanistic distinction that immunologic risk is governed primarily by the structure of the R1 side chain, not by the β-lactam core common to penicillins and cephalosporins1,2. Cefazolin possesses an R1 side chain structurally distinct from those of other cephalosporins and penicillins, thereby minimizing the likelihood of cross-reactive hypersensitivity responses. Contemporary allergy and immunology literature converges on the conclusion that cefazolin has a low-risk profile for cross-reactivity, a result reaffirmed by these surgical data. The clinical implications are considerable. Substituting cefazolin with alternative agents, such as vancomycin or clindamycin, is associated with decreased efficacy for infection prophylaxis, greater potential for adverse drug reactions, and increased health-care resource utilization3,4. This study extends extant literature by demonstrating that not only is cefazolin safe in patients with a cephalosporin allergy, but the use of alternative agents may impart a greater risk of avoidable allergic or adverse events. As with all retrospective studies using large databases, the interpretation of results warrants caution. Allergy documentation was heterogeneous, and cefazolin administration was ultimately at the discretion of the treating surgeons, introducing the potential for selection bias. Jolissaint et al. appropriately note that, even among patients noted to have had allergic reactions to cefazolin, mild reactions predominated. Remarkably, 1 individual with a recorded history of anaphylactic reaction to cefazolin received the drug without incident, underscoring the imperfect reliability of historical allergy documentation. It is plausible that patients with genuine severe hypersensitivity to cefazolin were excluded from cefazolin exposure in this cohort. Nonetheless, the absence of clinically important reactions among hundreds of exposed patients is compelling, particularly given that reported allergies are typically vague or mild. Electronic health record allergy notations are frequently based on patient-reported reactions, which may represent non-immunologic intolerances or manifestations of the underlying disease, and are often perpetuated without systematic verification or correction. The broader implications of these data are in harmony with evolving national and international guidelines, which recommend discontinuing the categorical avoidance of β-lactam antibiotics in patients who are allergic to a cephalosporin in favor of a risk-stratified, mechanistic approach. For instance, a patient with well-documented anaphylaxis to cefazolin should not receive the drug, whereas those with non-severe or ambiguous reactions to structurally distinct cephalosporins (e.g., cefalexin) may safely do so. This paradigm supports more effective and safer perioperative antibiotic stewardship, minimizing unnecessary exposure to inferior alternatives. For arthroplasty practitioners, the evidence supports maintaining cefazolin as the prophylactic standard for most patients, including many individuals with a reported cephalosporin allergy. Notably, I report the exclusive use of cefazolin for over 7 years, supported by data published in 20215. Jolissaint et al. merit recognition for their valuable and timely contribution to correcting persistent misconceptions regarding perioperative antibiotic prophylaxis and cephalosporin allergy. Their findings substantiate the continued use of cefazolin as the default agent for infection prevention in joint arthroplasty, even among patients with a cephalosporin allergy.
Bassam A. Masri (Thu,) studied this question.