In Vitro Activity of Ceftaroline to MRSA Isolates: A Multicenter Study

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) is an emerging pathogen that cause severe community-and hospital-acquired infections. Studies continue on searching alternatives due to the limited number of therapeutic options in MRSA infections. Ceftaroline is a wide-spectrum new generation cephalosporin which has been begun to be used in treatment of skin and respiratory tract infections caused by MRSA. The aim of this study was to investigate the in vitro activity of ceftaroline against MRSA strains isolated from various clinical specimens in microbiology laboratories of seven hospitals located at different provinces (Bolu, Samsun, Rize, Tekirdag, Sakarya, Amasya, Osmaniye) of Turkey. A total of 192 MRSA isolates (89 skin/wound/abscess, 38 blood, 36 respiratory tract, 29 urine/sterile body fluids/catheter) were included in the study, and ceftaroline susceptibilities of the strains were detected by broth microdilution method. MIC values of 181 (94.3%) isolates were determined as ≤ 1 μg/ml meaning of susceptible according to the criteria of CLSI, and MIC values of 11 (5.7%) isolates were found as 2 μg/mL indicating intermediate susceptibility. The range of MIC values of the isolates was found between 0.25-2 μg/ml. The rates of intermediate isolates have varied between 0-12.5% from the participating centers. MIC<inf>50</inf> and MIC<inf>90</inf> values of all the isolates were determined as 0.5 μg/ml and 1 μg/ml, respectively. No significant differences were found between the centers in terms of mean MIC values (p> 0.05). MIC<inf>50</inf> and MIC<inf>90</inf> values in Samsun and Bolu isolates were found to be the same with the whole group, however, MIC <inf>50</inf> and MIC<inf>90</inf> were 0.5 μg/ml and 0.5 μg/ml in Amasya isolates and 1 μg/ml and 1 μg/ml in Rize, Tekirdag, Osmaniye and Sakarya isolates, respectively. When evaluating MIC<inf>50</inf> and MIC<inf>90</inf> values and isolation rates of intermediate strains according to the specimen types, there were no significant differences (p> 0.05). Susceptibility rates to ceftaroline and the distribution profiles of MIC values of the isolates obtained from seven centers of Turkey have been detected similar with the previous American and European reports. With this study, initial data on the activity of ceftaroline against MRSA were obtained from Turkey. These preliminary findings indicate that ceftaroline is effective even on Turkish isolates and can be a suitable treatment in cases requiring wide-spectrum antimicrobiotic use, however further large-scaled studies are needed.