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Background: Breast cancer (BC) is the most malignancies in worldwide among women. Staphylococcus aureus is one of the most common agents responsible for overt and subclinical BC infections. Methicillin-resistant S. aureus (MRSA) have a high ability to resist β-lactam antibiotics and multidrug resistance (MDR). These strains increase the risk and severity of infections associated with BC.
Objectives: According to our knowledge, this study is a first nationwide, and was aimed to detect MRSA strains by phenotypic methods and study correlation between infections caused by MRSA and BC among women.
Methods: The current study was conducted at oncology center in Babylon City during the period of November (2019) to January (2020). Ages of patients were ranged from (20-80) years. Two hundred and sixteen randomly patients with BC were enrolled. S. aureus was detected using microbiological and biochemical tests. Isolates of MRSA were detected by five different phenotypic methods using the cefoxitin disc diffusion (FOXDD) method as a reference standard for mecA gene detection. Other phenotypic methods including: chromogenic assay, oxacillin disc diffusion (OXDD) and oxacillin, methicillin HiComb E-test [OX, (Meth E-test)].
Results: Of the 130 S. aureus isolates, 40 (30.7%) and 90 (69.3%) were confirmed using FOXDD test as MRSA and methicillin-sensitive S. aureus (MSSA), respectively. However, chromogenic assay and OX (E-test) were highly effective for detecting MRSA because they were recorded isolation rates for MRSA 39 (30.0%) and 38 (29.3%), respectively. Meth (E-test) gave lower result compared with other phenotypic tests, detecting 35 (26.9%) MRSA isolates. All MRSA isolates were recognized as completely sensitive against levofloxacin, vancomycin, linezolid and nitrofurantoin. Tetracycline 28 (70%) and erythromycin 27 (67.5%) were determined to be agents with the highest resistance. 25 (62.5%) of MRSA isolates in the current study were MDR. The highest percentage of MDR-MRSA were observed in class three of antibiotics 9 (22.5%). The lowest percentage is observed in a class four and seven of antibiotics 3 (7.5%).
Conclusions: Isolates of S. aureus were more presented in BC infections and the elderly groups were most affected, while MRSA isolates were found in a low rate but worrisome because that all these isolates were resistant to all β-lactam antibiotics and most of these isolates were MDR. The FOXDD method is more efficient and accurate for MRSA detection than other phenotypic methods.