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The synergistic effects of antimicrobial nanostructures with antibiotics present a promising solution for overcoming resistance in methicillin-resistant Staphylococcus aureus (MRSA). Previous studies have introduced iron as a novel coating for silver nanoparticles (AgNPs) to enhance both economic efficiency and potency against S. aureus. However, there are currently no available data on the potential of these novel nanostructures to reverse MRSA resistance. To address this gap, a population study was conducted within the MRSA community, collecting a total of 48 S. aureus isolates from skin lesions. Among these, 21 isolates (43.75%) exhibited cefoxitin resistance as determined by agar disk diffusion assay. Subsequently, a PCR test confirmed the presence of the mecA gene in 20 isolates, verifying them as MRSA. These results highlight the cefoxitin disk diffusion susceptibility test as an accurate screening method for predicting mecA-mediated resistance in MRSA. Synergy tests were performed on cefoxitin, serving as a marker antibiotic, and iron-coated AgNPs (Fe@AgNPs) in a combination study using the checkerboard assay. The average minimal inhibitory concentration (MIC) and fractional inhibitory concentration (FIC) of cefoxitin were calculated as 11.55 mg/mL and 3.61 mg/mL, respectively. The findings indicated a synergistic effect (FIC index < 0.5) between Fe@AgNPs and cefoxitin against 90% of MRSA infections, while an additive effect (0.5 ≤ FIC index ≤ 1) could be expected in 10% of infections. These results suggest that Fe@AgNPs could serve as an economically viable candidate for co-administration with antibiotics to reverse resistance in MRSA infections within skin lesions. Such findings may pave the way for the development of future treatment strategies against MRSA infections., Competing Interests: Declarations Competing interests The authors declare that there was no conflict of interest in the current experiment. Ethical Approval No animal or human study was done in this experiment., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: Acinetobacter baumannii resistant strains lead to increased mortality, treatment costs, and an increase in the length of hospitalization. Nowadays, nanoparticles are considered a substitute for antibiotics. This study aimed to determine the MIC of Silver (Ag) and Zinc Oxide (ZnO) Nanoparticles (NPs) on Biofilm-Producing Acinetobacter baumannii and determine the relationship between MIC and frequency of efflux pump genes in cutaneous specimens in Shiraz, Southwest Iran in 2021-2022., Methods: In this study, specimens were collected from April 2021 to June 2022 at Namazi and Faqihi Hospitals in Shiraz. Investigation of biofilm production in multidrug resistance (MDR) isolates was done by the microtiter plate method. Synthesized nanoparticles were characterized by UV-vis spectrum, X-ray diffraction (XRD), and electron microscopy. The MIC of AgNPs and ZnONPs for isolates was done using the method described in the CLSI guideline (2018). The antibacterial effect of MIC of NPs on inanimate objects was done by colony counts. The prevalence of efflux pump genes (adeR, adeC, adeA, abeM, adeK, adeI) was also investigated by PCR technique., Results: The highest ceftriaxone resistance (68%) and lowest colistin resistance (7%) were identified. 57% of isolates were MDR. In addition, 71.9% could produce biofilm and 28.1% of isolates could not produce biofilm. The average size of AgNPs and ZnONPs in the present study is 48 and < 70 nm, respectively. The nanoparticles were spherical. The MIC and the MBC of the ZnONPs were in the range of 125 to 250 µg/mL respectively. Also, for AgNPs, the MIC and the MBC were in the range of 62.5 to 250 µg/ml, respectively. AbeM gene had the highest frequency and the AdeK gene had the lowest frequency. Statistical analysis showed that there is a relationship between the frequency of adeA, adeC, and adeM genes with the MIC of AgNPs and ZnONPs., Conclusion: According to the results of the present study, inanimate objects such as scalpels in contact with AgNPs (6000 µg/ml for 240 min) or ZnONPs (5000 µg/ml for 120 min) can be free of biofilm producing Acinetobacter baumannii  with efflux pump genes., (© 2024. The Author(s).)