Cefazolin Sodium

Cefazolin sodium exerts its bactericidal activity through inhibition of bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), thereby blocking the transpeptidation reaction essential for peptidoglycan cross-linking. However, the efficacy of cefazolin can be compromised by the cefazolin inoculum effect (CzIE), a phenomenon where cefazolin activity diminishes at high bacterial densities such as those found in endocardial vegetations or abscesses. The molecular basis of CzIE involves the production of specific allotypes (particularly type A and type C) of the staphylococcal β-lactamase enzyme BlaZ, which hydrolyzes cefazolin. At standard inocula, cefazolin MICs remain low, while at high inocula, MICs increase to ≥16 mg/L. The prevalence of CzIE among MSSA isolates ranges from 0% to 55% depending on geographic region and bacterial lineage.

Fig. 1 CzIE cefazolin inoculum effect, MIC minimum inhibitory concentration. (Srivastava P.; et al. 2025)

Cefazolin sodium was loaded into chitosan nanoparticles with a particle size of 227 nm and incorporated into ionic cross-linked hydrogel films composed of sodium alginate and pectin for wound dressing applications. The films were cross-linked via calcium chloride to improve mechanical strength upon exposure to wound fluid. The optimized formulation with 0.5 percent cross-linker concentration showed sustained drug release, appropriate swelling behavior, good mucoadhesion, and significantly improved antibacterial activity compared to films with higher cross-linker concentrations.

Fig. 2 Preparation of CFZ nanoparticles and CFZ nanoparticles-loaded hydrogel film. (Shahzad A.; et al. 2019)