The Effect of Rotating Magnetic Field on Susceptibility Profile of Methicillin-Resistant Staphylococcus aureus Strains Exposed to Activity of Different Groups of Antibiotics.

Marta Woroszyło,Grzegorz Chodaczek,Karol Fijałkowski,Marcin Wardach,Adam Junka,Daria Ciecholewska-Juśko,Bartłomiej Dudek

doi:10.3390/ijms222111551

Abstract

Methicillin-resistant strains of Staphylococcus aureus (MRSA) have become a global issue for healthcare systems due to their resistance to most β-lactam antibiotics, frequently accompanied by resistance to other classes of antibiotics. In this work, we analyzed the impact of combined use of rotating magnetic field (RMF) with various classes of antibiotics (β-lactams, glycopeptides, macrolides, lincosamides, aminoglycosides, tetracyclines, and fluoroquinolones) against nine S. aureus strains (eight methicillin-resistant and one methicillin-sensitive). The results indicated that the application of RMF combined with antibiotics interfering with cell walls (particularly with the β-lactam antibiotics) translate into favorable changes in staphylococcal growth inhibition zones or in minimal inhibitory concentration values compared to the control settings, which were unexposed to RMF. As an example, the MIC value of cefoxitin was reduced in all MRSA strains by up to 42 times. Apart from the β-lactams, the reduced MIC values were also found for erythromycin, clindamycin, and tetracycline (three strains), ciprofloxacin (one strain), gentamicin (six strains), and teicoplanin (seven strains). The results obtained with the use of in vitro biofilm model confirm that the disturbances caused by RMF in the bacterial cell walls increase the effectiveness of the antibiotics towards MRSA. Because the clinical demand for new therapeutic options effective against MRSA is undisputable, the outcomes and conclusions drawn from the present study may be considered an important road into the application of magnetic fields to fight infections caused by methicillin-resistant staphylococci.

Highlights

In the last decades, antimicrobial resistance has become a significant health issue
It can be assumed that the exposure to the rotating magnetic field (RMF) was long enough to obtain a well-developed bacterial lawn, which did not change during further incubation, and a stable antimicrobial effect
In the analyses with amoxicillin combined with clavulanic acid, differences in minimum inhibitory concentration (MIC) values were observed for all Methicillin-resistant strains of Staphylococcus aureus (MRSA)

Summary

Introduction

Antimicrobial resistance has become a significant health issue. The increasing tolerance to antibiotics is observed in a variety of bacterial species, regardless of their origin (community or clinical) [1,2]. Methicillin-resistant Staphylococcus aureus strains, referred to as MRSA, have acquired resistance to such β-lactam antibiotics as penicillins, cephalosporins (with the exception of ceftaroline and ceftobiprole), and to carbapenems, commonly considered antibiotics of the last resort in the treatment of hardto-heal infections. These resistant staphylococcal strains are presently thought to comprise. MRSA strains have developed resistance to other antibiotic groups, including aminoglycosides, fluoroquinolones or macrolides, becoming the first “super-bugs”, i.e., multidrug-resistant (MDR) pathogens [7]

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