Reduced In Vitro Activity of Ceftaroline by Etest among Clonal Complex 239 Methicillin-Resistant Staphylococcus...

Area of Science:

• Infectious Diseases
• Antimicrobial Resistance
• Clinical Microbiology

Background:

• Methicillin-resistant Staphylococcus aureus (MRSA) poses a significant global health threat.
• Emerging resistance to antibiotics like ceftaroline in MRSA necessitates ongoing surveillance.
• Specific MRSA clones, such as CC239, are frequently associated with multidrug resistance.

Purpose of the Study:

• To determine the susceptibility of clinical MRSA isolates to ceftaroline.
• To investigate the prevalence of ceftaroline nonsusceptibility in relation to specific MRSA clones and multidrug resistance phenotypes.
• To assess the implications of observed resistance patterns for empirical ceftaroline therapy.

Main Methods:

• Susceptibility testing of 421 MRSA clinical isolates using Etest for ceftaroline.
• Identification of clonal complex 239 (CC239) using appropriate typing methods.
• Phenotypic characterization of multidrug resistance in the isolates.
• Statistical analysis to compare ceftaroline nonsusceptibility rates between different groups.

Main Results:

• Overall ceftaroline nonsusceptibility was 16.9% (68/421).
• Ceftaroline nonsusceptibility was significantly higher in CC239 isolates (41.1%) and multidrug-resistant isolates (35.5%) compared to others (P < 0.0001).
• Clonal complex 239 accounted for 33.5% of isolates, and 40.9% exhibited a multidrug-resistant phenotype.

Conclusions:

• High rates of ceftaroline nonsusceptibility were observed in prevalent multidrug-resistant MRSA clones, particularly CC239.
• The findings suggest that empirical use of ceftaroline may be limited for infections caused by these resistant MRSA strains.
• Continued monitoring of ceftaroline susceptibility in clinical MRSA isolates is crucial for guiding treatment strategies.