Cefazolin Lack of Cross-Reactivity References:

1. Uyttebroek et al. J Allergy Clin Immunol Pract 2016;4(6):1232-6 (lack of skin sensitivity between cephalosporins including cefazolin).
2. Blumenthal et al. Antimicrob Agents Chemother 2014;58(6):3137-43 (cefazolin fine with nafcillin allergy).
3. Romano et al. J Allergy Clin Immunol 2015;136(3):685-91 (via drug-specific assays/challenge testing distinction between cephalosporins including cefazolin).
4. Zagursky et al. J Allergy Clin Immunol Pract 2018;6(1):72-81 (great review article that summarizes cefazolin cross-reactivity/skin-reactivity data - highlight essentially no true cross-reactivity)

The review by Zagursky et al includes the below as citations:

Varela et al. J Investig Allergol Clin Immunol 2009;19:164-5. (cefuroxime against other cephalosporins, including cefazolin).

Montanez et al. Chem Res Toxicol 2011;24:706-17. (antigenic determinants of cephalosporin allergies).

Somech et al. Int Arch Allergy Immunol 2009;150:205-9. (skin-testing challenge testing with different cephalosporins).

Tuyls et al. J Allergy Clin Immunol 2016;137:331.

Pipet et al. A statement on cefazolin immediate hypersensitivity: data from a large database, and focus on the cross-reactivities. Clin Exp Allergy 2011;41:1602-8.

Cefuroxime references for cross-reactivity: 

1. Antunez et al. J Allergy Clin Immunol 2006;117(2):404-10.
2. Hasdenteufel et al. Ann Pharmacother 2007;41:1069-72.

Clavulanate reference: Blanca-Lopez et al. Allergy 2015;70(8):1013-9.

Tazobactam reference: Rank M et al. Anaphylaxis to piperacillin-tazobactam despite a negative penicillin skin-test. Allergy: Europ J Allergy Clin Immunol 2007;62(8):964-5.