Ceftaroline Exhibits Promising In Vitro Activity Against Methicillin-Resistant Staphylococcus aureus Clinical Isolates From Alexandria, Egypt.

Abstract

Introduction: Ceftaroline is a fifth-generation cephalosporin that was recently introduced into the Egyptian market for the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections. However, limited data are available regarding the susceptibility of MRSA isolates in Egypt to this antibacterial agent. This study aimed to determine the susceptibility of MRSA strains recovered from different clinical samples to ceftaroline and to investigate the prevalence of the mecA and mecC resistance genes. Methods: A total of 412 MRSA isolates were selected from 520 Staphylococcus aureus (S. aureus) samples. Identification and antibiotic susceptibility testing were performed using the VITEK-2 compact system. Molecular identification of the nuc gene, encoding nuclease enzyme, a species-specific marker for S. aureus, and the mecA and mecC genes associated with methicillin resistance was performed using the polymerase chain reaction (PCR) technique. Moreover, the in vitro activity of ceftaroline was explored using the disc diffusion method, and its minimum inhibitory concentration (MIC) was determined according to the Clinical Laboratory Standards Institute (CLSI) criteria. Staphylococcal Protein A (spa) typing was carried out for ceftaroline nonsusceptible strains as determined by MIC. Results: Most isolates were recovered from skin and soft tissue infections. Of the 412 clinical isolates, 407 (98.7%) were susceptible to ceftaroline, with an MIC of ≤ 1 mg/L, while five isolates (1.3%) showed a susceptible dose-dependent (SDD) profile with MIC values of 2-4 μg/mL. No isolates were resistant to ceftaroline. All isolates carried the nuc gene, 94% harbored mecA, while mecC was undetected. Of the five SDD isolates, three were identified as spa type t037, corresponding to ST-239, ST-240, or ST-241 by multilocus sequence type (MLST), whereas the two remaining isolates were untypeable. Conclusions: From various clinical samples, ceftaroline demonstrated excellent in vitro activity against MRSA strains, positioning it as a promising therapeutic option for managing MRSA infections in Egypt.