Objective: The aim of this study was to determine antimicrobial resistance profiles of methicillin-resistant Staphylococcus aureus (MRSA) isolates from clinical samples from patients hospitalized during 2015–2017 in hospitals of ­Masovian district in Poland. Materials and Methods: Antimicrobial resistance of 112 MRSA isolates was tested with a disc diffusion method. Isolates were examined for methicillin resistance using a 30 µg cefoxitin disk. Resistance was confirmed by PCR detection of the mecA gene. PCR was also used to determine spa gene polymorphism in X-region. Results: A large number of MRSA isolates showed resistance to levofloxacin (83.9%), ciprofloxacin (83%), erythromycin (77.7%) and clindamycin (72.3%). A lower number of MRSA isolates showed resistance to tetracycline (10.7%), amikacin (14.2%), gentamicin and trimethoprim with sulfamethoxazole (8.0%). None of the MRSA isolates were resistant to linezolid and teicoplanin. Among MRSA isolates, 92.9% were multidrug-resistant (MDR). Resistance to erythromycin, clindamycin, ciprofloxacin and levofloxacin was the most common resistance pattern among MDR MRSA isolates. The highest number of isolates was resistant to 4 groups of antimicrobials (53.8%). The number of drugs to which MRSA isolates were resistant in 2017 was significantly higher than that in 2016 (p = 0.002). The size polymorphism analysis of X fragment of the spa gene revealed high genetic diversity of the investigated group MRSA isolates. Conclusion: This study demonstrates that in the hospital environment, MRSA isolates can quickly acquire new antimicrobial resistance determinants and that knowledge of current resistance patterns is important for the effective treatment of infections caused by MDR MRSA.

The aim of this study was to evaluate the ability of 0.1% thyme oil (TO), trans-cinnamaldehyde (TC), ferulic acid (FA), p-coumaric acid (p-CA), caffeic acid (CA), lavender essential oil (LO), geranium essential oil (GO) and tee tree oil (TTO) to control biofilms formed by methicillin-resistant Staphylococcus aureus (MRSA) strains. Depending on the strains, TO reduced 59.7-85% of biofilm mass, while TC 52.9-82.4% after 48 h of treatment. Reduction of metabolic activity of biofilms in ranges 79.3-86% and 85.9-88.7% was observed after 48 h of TC and TO of treatment, respectively. In the case of some strains, reduction of biofilm mass in the presence of FA, CA, GO, LO and TTO was not observed. This study showed that TO and TC might have therapeutic potential as an inhibitory agents for use in MRSA biofilm-related infections.

Analysis of Lamiaceae essential oils (EOs) by GC-FID-MS revealed the presence as the major constituents of linalool (16.8%), linalyl acetate (15.7%) in Lavandula angustifolia, menthol (29.0%), menthone (22.7%), menthyl acetate (19.2%) in Mentha x piperita, terpinen-4-ol (27.1%), (E)-sabinene hydrate (12.1%), γ-terpinene (10.0%) in Origanum majorana, α-thujone (19.5%), camphor (19.0%), viridiflorol (13.5%) in Salvia officinalis, thymol (61.9%), p-cymene (10.0%), γ-terpinene (10.0%) in Thymus vulgaris. Based on the MIC and MBC values (0.09-0.78 mg/mL) and ratio MBC/MIC showed that EO from T. vulgaris (TO) had the strong inhibitory and bactericidal effect against multidrug-resistant Staphylococcus aureus. The bacterial cells were total killed by TO at 2MIC concentration after 6 h. The higher concentrations of other EOs were needed to achieve bactericidal effects. The strong bactericidal effect of TO against these bacteria indicates the possibility of topical use of TO but it requires research under clinical conditions.

Staphylococcus aureus is a Gram-positive bacterium, which can cause serious bacterial infections in humans. It constitutes an important etiological factor of many diseases, for instance, soft tissue and skin infections (including skin boils and abscesses), as well as life-threatening necrotizing pneumonia or toxic shock syndrome. It is estimated that about 25–30% of people are carriers of S. aureus mainly in the anterior nostrils. A smaller percentage of people are carriers of methicillin-resistant S. aureus (MRSA). In accordance with its definition, methicillin-resistant S. aureus is resistant to almost all β-lactam antibiotics. This phenomenon is mainly caused by the presence of penicillin-binding protein in the cell wall – PBP2a, which is the product of the mecA gene, which is part of the complex called SCCmec (staphylococcal cassette chromosome mec). Methicillin-resistant S. aureus (MRSA) results in endemic in hospitals around the world and are one of the leading causes of morbidity and mortality in society. Infections initiated by hospital strains of MRSA (health care-associated MRSA, HA-MRSA) concern mainly immunocompromised patients after surgery. In addition, there are populations of acommunity-associated MRSA (CA-MRSA) strains and populations of livestock-associated MRSA (LA-MRSA) strains. The treatment of infections with MRSA etiology, after exhausting the possibilities of standard antibiotic therapy with the use of i.e. vancomycin, is based on treatment with new-generation antibiotics, such as dalbavacin.