## 4 Discussion  
MRSA strains, which are also characterized by multidrug resistance, may develop cross-resistance to antiseptics [2]. Scientific literature reports mainly focus on the occurrence of cross-resistance between CHG and benzalkonium chloride [39]. However, recently, there have been reports of bacteria acquiring resistance to other antiseptics, e.g., PHMB or OCT, which were considered to be the so-called golden remedies\" in wound antisepsis [17; 40; 41]. Antiseptics are widely used in medical care. They are used by hospitals, clinics, private specialist medical practices, dental offices and also beauty salons. Therefore, emerging antiseptic resistance should be constantly monitored. It is necessary to develop new formulations with antimicrobial activity, including natural-based compounds exhibiting other beneficial properties, such as immunostimulatory or anti-inflammatory. Our studies confirmed that the _S. aureus_ ATCC 43300 (MRSA) strain was susceptible to four (Braunol, CITROclorex 2%, Octenisept and Prontoderm Solution) out of five tested antiseptics. MIC testing, using the microdilution method, did not reveal susceptibility of the tested strain to Microdacyn 60 Wound Care, which contains hypochlorous acid (40 ppm) and sodium hypochlorite (40 ppm). This lack of antibacterial activity does not necessarily mean bacterial resistance to the active compounds in the analyzed preparation, but may be related to its killing activity at higher concentrations (>50.0%). Similar observations were described in a study by [PERSON] et al. [42], who confirmed that Microdacyn 60 Wound Care was inactive against _S. aureus_ at concentrations ranging between 50% and 0.1%. Moreover, literature reports reveal that the antibacterial effect of chlorine-releasing compounds depends on the concentration of Cl ions in the antiseptic [43]. [PERSON] et al. [44] proved  
Figure 2: Fractional inhibitory concentration index (FICI) of combinations of selected commercial antiseptics and natural agents. FICI \(\leq\) 0.5—synergistic effect; 0.5 \(<\) FICI \(\leq\) 1.0—additive effect; 1.0 \(<\) FICI \(<\) 4.0—no effect; FICI \(\geq\) 4.0— antagonistic effect. a lack of antimicrobial activity in compounds releasing chlorine at a concentration of <670 ppm. It is worth emphasizing that Microdacyn 60 Wound Care is characterized by a total concentration of Cl ions of 80 ppm. There are many literature reports on the effect of PVP-I, whose MIC against MRSA strains is varied and usually ranges between 256 ug/mL and 5000 ug/mL [45; 46; 47]. However, there are few reports on the effects of Braunol itself, which contains 7.5 g of povidone iodine per 100 mL of solution. Studies conducted by [PERSON] et al. [48] showed that the MIC of Braunol against the methicillin-susceptible _S. aureus_ ATCC 29213 (MSSA) strain was 4%. Their result was similar to that obtained in this study, where the MIC and MBC values against the MRSA strain were 6.25% and 12.5%, respectively. There are no reports in the scientific literature on the MIC value of CITROclorex 2% (which contains CHG at a concentration of 2 g/100 mL of solution and ethyl alcohol at a concentration of 73.6 g/100 mL of solution) against _S. aureus_ strains. Information on the action of this preparation against bacteria (including strains with the MRSA phenotype) is only provided by producers and distributors of this antiseptic in the product information sheet. Based on the conducted research, it was found that this preparation was characterized by the best antistaphylococcal properties (MIC = 0.01%, MBC = 0.10%), which may indicate the effective action of the combination of CHG with ethyl alcohol against the tested MRSA strain. Interestingly, this observation was also confirmed in a study conducted by [PERSON] et al. [49]. The authors noted that the combination of 1% CHG and 61% ethyl alcohol contributed to a more significant reduction in microorganisms than 4% CHG (without ethyl alcohol) or 61% ethyl alcohol (without CHG).