###### Abstract  
This study aimed to biosynthesisze zinc oxide nanoparticles (ZnO NPs) using _Pleurotus_ \(s\) \(s\) \(p\) \(t\) \(s\) \(t\) \(s\) \(t\) \(s\) \(t\) \(s\) \(t\) _s  
Nanoparticles (NPs) are regarded as microscopic particles having a size ranging from 1 to 100 nm [7]. They exhibit unique properties due to the quantum confinement effect; however, the influence of shapes and structures of the nanoparticles affects the reactivity and toughness of the nanomaterial [8]. These attributes of nanoparticles are due to their variations in shape, surface-to-volume ratio, size, and composition. These properties render their unique physical, chemical, and biological properties that may potentially be of benefit in numerous sectors such as medicines, agriculture, pharmaceuticals, electronics, and cosmetics [9]. Hence, nanoparticles have shown great potential in biomedical applications in managing infectious diseases that are usually caused by multidrug resistant organisms [10]. Currently, antimicrobial-resistant diseases, including hospital-acquired Gram-negative bacterial infections, and their associated morbidity and mortality, have grown at an alarming rate [11]. Hence bacteria such as _Pseudomonas aeruginosa_, _Enterococcus facium_, _Klebsiella pneumoniae_, _Staphylococcus aureus_, _Acinetobacter baumannii_, and _Enterobacter_ are considered as multidrug-resistant bacterial species causing nosocomial infections [12]. The rise in multidrug-resistant pathogens is significantly affecting the global economy and causing catastrophic effects in the health care system worldwide, thus resulting in increases in mortality and morbidity, a loss of certainty regarding orthodox drugs, and a rise in treatment costs [12]. Previously, multidrug-resistant pathogens, such as _Enterococci_ and _Pseudomonas_, were associated with rapid nosocomial infections. Additionally, _Enterococci_ has been recognized as the second-leading cause of nosocomial infections worldwide [13] ([PERSON], [13] 2020), whereas _P. aeruginosa_ was found to contribute to 10-11% of all nosocomial infections [14]. There have been many attempts to eradicate multidrug-resistant bacteria; however, one of the major problems is that some organisms such as _P. aeruginosa_ become more virulent when co-cultured with other Gram-positive bacteria [15; 12]. Other researchers have suggested that _P. aeruginosa_ is aggravated during coinfection with _E. faecalis_[16]. Therefore, it is paramount to find alternative effective and safe antibacterial responses, especially those with multiple mechanisms of resistance [17; 18; 19]. Recently, [PERSON] et al. [18] explored the use of mushrooms as an antimicrobial agent since mushrooms produce a large number of bioactive metabolites with therapeutic potential, as reported earlier by [19]. These metabolites produced by mushrooms have immunomodulatory, cardiovascular, antifibrotic, antidiabetic, antitumor, liver protection, anti-inflammatory, antiviral, antioxidant, and, mostly, antimicrobial properties [20]. Thus, mushrooms may be a good alternative source of natural antibiotics having compounds with a low molecular weight (LMW) or high molecular weight (HMW) [21]. The numerous bioactive compounds found in mushrooms render mushrooms a new potential source for the synthesis of NPs [22]. This finding follows a major focus on NPs, which showed that NPs prevent microbial drug-resistance in some cases. This is because their mode of action is via direct contact with the bacterial cell wall, meaning there is no necessity to penetrate the cell. Hence, this provides hope that NPs do not promote bacterial resistance [23]. Zinc oxide (ZnO) NPs are mostly known to have distinct antibacterial, antimicrobial, and anti-fungal properties compared to other oxides [24]. However, the synthesis of zinc oxide NPs using _P. ostreatus_ mushroom has been rarely explored in the past because ZnO NPs have been mainly produced using approaches such as the sol-gel, solvothermal, hydrothermal, and micro-emulsion methods [25], and solution combustion synthesis [26].