Correlation between mazEF Toxin-Antitoxin System Expression and Methicillin Susceptibility in Staphylococcus aureus and Its Relation to Biofilm-Formation.

Yasmine El Kholy,Rania Y Shash,Aya Abd El Rahman

doi:10.3390/microorganisms9112274

Yasmine El Kholy, Rania Y Shash + Show 1 more

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https://doi.org/10.3390/microorganisms9112274

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Journal: Microorganisms	Publication Date: Oct 31, 2021
Citations: 4	License type: CC BY 4.0

Affiliation: Cairo University

Abstract

Methicillin resistance in Staphylococcus aureus has become prevalent globally. Moreover, biofilm-formation makes it more difficult to eradicate bacteria by antibiotics. The mazEF toxin-antitoxin system encodes for mazF, which acts as an endoribonuclease that cleaves cellular mRNAs at specific sequence motifs (ACA), and mazE, which opposes the mazF action. Our goal was to detect mazEF expression in methicillin-resistant S. aureus (MRSA) isolates compared with methicillin-sensitive S. aureus (MSSA) isolates and determine its relation to methicillin susceptibility as well as biofilm-formation. According to their susceptibility to cefoxitin disks, 100 S. aureus isolates obtained from patients admitted to Cairo University Hospitals were categorized into 50 MSSA and 50 MRSA according to their susceptibility to cefoxitin disks (30 µg). Antimicrobial susceptibility and biofilm-formation were investigated using the disk diffusion method and tissue culture plate method, respectively. Finally, using real-time PCR, mazEF expression was estimated and correlated to methicillin susceptibility and biofilm formation. Both MRSA and MSSA isolates showed the best sensitivity results with linezolid and gentamicin, where about 88% of MRSA isolates and 96% of MSSA isolates were sensitive to linezolid while 76% of MRSA isolates and 84% of MSSA isolates were sensitive to gentamicin. MRSA isolates were significantly more able to form biofilm than MSSA isolates (p-value = 0.037). The mazEF expression was significantly correlated to methicillin resistance in S. aureus (p-value < 0.001), but not to biofilm-formation.

Highlights

S. aureus leads to many community and nosocomial-acquired infections [1]
Both methicillin-resistant S. aureus (MRSA) and methicillinsensitive S. aureus (MSSA) isolates showed the best sensitivity results with linezolid and gentamicin, where about 88% of MRSA isolates and 96% of MSSA isolates were sensitive to linezolid while 76% of MRSA isolates and 84% of MSSA isolates were sensitive to gentamicin
Of the tested isolates were sensitive to linezolid and gentamicin, respectively, whereas, within MSSA isolates, about 96% and 84% of the tested isolates were sensitive to both agents, respectively

Summary

Introduction

S. aureus leads to many community and nosocomial-acquired infections [1]. It results in various diseases, either localized skin infections or fatal systemic diseases [1].The staphylococcal mec operon encodes for a different penicillin-binding protein called (PBP2a) which exhibits less methicillin binding affinity. S. aureus leads to many community and nosocomial-acquired infections [1]. It results in various diseases, either localized skin infections or fatal systemic diseases [1]. The staphylococcal mec operon encodes for a different penicillin-binding protein called (PBP2a) which exhibits less methicillin binding affinity. This makes staphylococci unsusceptible to all β-lactam antibiotics. Staphylococcal chromosomal cassettes contain genes coding for resistance to antibiotics other than βlactams [2]. Resistance towards many other antibiotics such as aminoglycosides, quinolones, macrolides-lincosamides-streptogramins, vancomycin, and linezolid has been shown in S. aureus [2]

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