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Evaluation of in Vitro Activity of Ceftaroline on Methicillin Resistant Staphylococcus Aureus Blood Isolates From Iran Publisher



Abdizadeh N1 ; Haeili M1 ; Kafil HS2 ; Ahmadi A3 ; Feizabadi MM4, 5
Authors
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Authors Affiliations
  1. 1. Department of Animal Biology, Faculty of Natural Sciences, University of Tabriz, Tabriz, Iran
  2. 2. Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
  3. 3. Pharmaceutical Nanotechnology Research Center, Biomedicine Institute, Tabriz University of Medical Sciences, Tabriz, Iran
  4. 4. Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
  5. 5. Thoracic Research Center, Imam Khomeini Hospital, Tehran University of Medical Sciences, Tehran, Iran

Source: Iranian Journal of Microbiology Published:2021


Abstract

Background and Objectives: Ceftaroline (CPT) is a novel cephalosporin with potent activity against methicillin-resistant Staphylococcus aureus (MRSA). Despite its recent introduction, CPT resistance in MRSA has been described worldwide. We aimed in the current study to evaluate the in vitro activity of CPT against 91 clinical MRSA and 3 MSSA isolates. Materials and Methods: Susceptibility of isolates to CPT was tested using E-test and disk diffusion (DD) method. The nucleotide sequence of the mecA gene and molecular types of isolates with reduced susceptibility to CPT were further studied to identify resistance conferring mutations in PBP2a and the genetic relatedness of the isolates respectively. Results: Overall, 92.5% of isolates were found to be CPT susceptible (MICs≤1mg/l) and 7 MRSA isolates were characterized with MIC=2mg/l and categorized as susceptible dose dependent. Compared to E-test, DD revealed a categorical agreement rate of 93.6% and the obtained rates for minor, major /very major error were found to be 6.3% and 0% respectively. The MRSA isolates with increased CPT MICs (n=7), belonged to spa types t030 (n=6) and t13927 (n=1) and all carried N146K substitution in PBP2a allosteric domain, except for one isolate which harbored a wild-type PBP2a. Conclusion: While resistance to CPT was not detected we found increased CPT MICs in 7.69% of MRSA isolates. Reduced susceptibility to CPT in the absence of mecA mutations is indicative of contribution of secondary chromosomal mutations in resistance development. © 2021 The Authors. Published by Tehran University of Medical Sciences.