ISSN: 0973-7510

E-ISSN: 2581-690X

Research Article | Open Access
Sara H. Mohamed1, Maram M.S. Elshahed1, Yasmine M. Saied1, Mahmoud S.M. Mohamed2 and Gamal H. Osman3,4,5
1Department of Microbiology, National Organization for Drug Control and Research, Giza, Egypt.
2Department of Botany and Microbiology, Faculty of Science, Cairo University, 12613, Giza, Egypt.
3Department of Biology, Faculty of Applied Science, Umm Al-Qura University, Makkah, Saudi Arabia.
4Research Laboratories Center, Faculty of Applied Science, Umm Al-Qura University, Makkah, Saudi Arabia.
5Agricultural Genetic Engineering Research Institute (AGERI), ARC, 12619, Giza, Egypt.
J Pure Appl Microbiol. 2020;14(3):1905-1916 | Article Number: 6474
https://doi.org/10.22207/JPAM.14.3.29 | © The Author(s). 2020
Received: 14/06/2020 | Accepted: 02/09/2020 | Published: 23/09/2020
Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) strains are widespread globally. Besides their virulence factors, the co-occurrence of antimicrobial and metal resistance has been reported. This study was designed to evaluate the antibiotic resistance and resistance phenotypes, investigate the occurrence of virulence factors, and detect heavy metal tolerance among MRSA strains. Antibiogram profiling was done as recommended by CLSI instructions. Resistance phenotypes were detected by D test, followed by characterization of enzymatic activities and biofilm formation assay. Antibacterial activity of different heavy metals was tested, and predictable synergistic assay was performed. Among MRSA strains collected, high resistance to ampicillin and amoxicillin/clavulanate (100%) and high susceptibility to clindamycin (70%) were obtained. Resistance phenotypes were detected as S, constitutive MLSB, inducible MLSB, and MS by percentages of 10%, 30%, 30% and 30% respectively. Virulence factors like lipolytic (50%) and hemolytic (70%) activity, and biofilm formation ability (100%) were detected. High resistance towards potassium and magnesium was observed. MTC of 500 ppm was detected for all isolates in case of cobalt and iron. In case of zinc and copper, MTC was detected as 500 ppm except for one isolate which was highly resistant, and 500 ppm for all isolates except for two isolates which were highly sensitive respectively. Magnesium in different concentrations (500 and 2000 ppm) showed synergistic activity with erythromycin and clindamycin. Results reveal high heavy metal tolerance among antibiotic resistant MRSA strains, in addition to the presence of virulence factors. Upcoming studies must be focused on the combination of sub-inhibitory concentration of different heavy metals with the available antibiotics.

Keywords

MRSA, biofilm, MLSB, heavy metals, S. aureus

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© The Author(s) 2020. Open Access. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License which permits unrestricted use, sharing, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.