## 4 Discussion
NBRCA seems to be more active against both bacteria, assuming that it coulddepend on the different composition and structure of this latter rubber which contains different compounds and accelerators. In a recent literature search regarding elastomers and their antimicrobial activity, it was found that there are two main areas of research, one more common on in vitro experiments and the other on the application of new molecules or active compounds in different fields. For instance, [PERSON] and colleagues investigated thermoplastic elastomers (TPEs) incorporated with six different formulations for mechanical and antiviral performance, showing that TPE samples containing zinc pyrithione and disodium octaborate tetrahydrate presented biocidal action against several pathogens (_Staphylococcus aureus_, Methicillin Resistant _S. aureus_, _Escherichia coli_, _Candida albicans_, _Aspergillus niger_, Adenovirus, Bovine Coronavirus, Poliovirus, and Norovirus), and these formulations can be used to develop antimicrobial products for multiple touchpoints within a vehicle and micro-mobility [8]. Some authors have demonstrated that silver is an antibacterial agent with high activity and limited bacterial resistance. The mechanism of action relies on positively charged silver ions (Ag\({}^{+}\)) attracting the sulfhydryl group on the enzyme protein in the bacteria. Particularly, in a Graphene oxide-Ag nanocomposite, bactericide action against the Gram-negative _E. coli_ occurred through disrupting bacterial cell wall integrity, whereas a bacteriostatic effect inhibiting cell division for Gram-positive _S. aureus_ was demonstrated [19; 20]. The compound silver and tannin modified hydroxyapatite may serve as a promising and easy-to-produce antimicrobial mineral for the development of antimicrobial orthopedic composite implants to prevent surgical infections [21], while for other clinical applications of elastomers, leakage resistance and the antimicrobial properties of porous liquid metal-elastomer composites for skin-interfaced bioelectronics were verified [22]. [PERSON] and colleagues incorporated Ag nanoparticles (AgNPs) into a silicone elastomer to assess their antimicrobial activity, along with their physico-mechanical properties and cytotoxic effects, for developing prosthetic liners, and measured the maximum antimicrobial activity vs. _S. aureus_ and methicillin-resistant _S. aureus_[23]. [PERSON] et al. demonstrated that polyurethane containing crystal violet and zinc oxide nanoparticles have excellent bactericidal activity against hospital-acquired pathogens, including multidrug-resistant _E. coli_, _Pseudomonas aeruginosa_, methicillin-resistant _S. aureus_, and endospores of _Clostridioides difficile_, hoping to implement their use to reduce the transmission of pathogens between people and the environment [24]. Antimicrobial activity was also tested in the textile industry in instances of medical and personal protection applications by examining four types of antimicrobial fillers, namely, metal oxides (zinc, titanium, and copper) and nanosilver, as fillers in Polyamide 12 fibers. In these studies, it was found that metal oxides combined with silver showed significantly higher antifungal activity than those with only a mixture of metal oxides [25]. Finally, [PERSON] et al. [6] tested innovative elastomers, different from those considered in this paper, against the three major mastitis pathogens (_S. aureus_, _S. agalaciae_, and _E. coli_), for their potential use during milking and in the food industry. They noticed that basic rubber materials have intrinsic antimicrobial activity, and, on the contrary, silicone elastomers did not exhibit the same action. Nevertheless, a significant decrease in bacterial survival curves was observed for all the formulations with additives, with different results in different formulations and manufacturing processes [6].