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Background A significant threat to the public's health is the rise in antimicrobial resistance among numerous nosocomial bacterial infections. This may be a detriment to present initiatives to enhance the health of immune-compromised patients. Consequently, attention has been devoted to exploring new bioactive compounds in the field of drug discovery from endophytes. Therefore, this study is the first on the production of l-tyrosine (LT) as a promising bio-therapeutic agent from endophytic fungi. Results A new endophytic fungal isolate has been identified for the first time as Rhizopus oryzae AUMC14899 from Opuntia ficus-indica (L.) and submitted to GenBank under the accession number MZ025968. Separation of amino acids in the crude extract of this fungal isolate was carried out, giving a higher content of LT, which is then characterized and purified. LT exhibited strong antibacterial and anti-biofilm activities against multidrug-resistant Gram-negative and Gram-positive bacteria. The recorded minimum inhibitory concentration (MIC) values ranged from 6 to 20 µg/ml. In addition, LT caused a strong reduction in biofilm formation and disrupted the preformed biofilm. Moreover, results indicated that LT supported cell viability, evidencing hemocompatibility and no cytotoxicity. Conclusion Our findings suggest that LT has potential as a therapeutic agent due to its potential antibacterial, anti-biofilm, hemocompatibility, and lack of cytotoxic activities, which may also increase the range of therapy options for skin burn infections, leading to the development of a novel fungal-based drug.

B ACTERIAL lung infections can be serious and life-threatening diseases in people of all ages. Recently, bacterial resistance to antibiotics has increased rapidly and the most serious concern is that some bacteria have become resistant to almost all of the easily available antibiotics. The present work aimed to study the relation between some of the expressed virulence factors and antibiotic resistance among local Gram negative bacteria isolated from infected lungs of patients attended Tanta University hospital, Egypt. Out of 70 different clinical specimens, 30 Gram negative isolates were obtained; 46.6% and 53.3% of total isolates were Pseudomonas aeruginosa and Enterobacteriaceae, respectively. All bacterial isolates were tested for their susceptibility against 24 antimicrobial agents as well as the ability to express some virulence factors including hemolysin, gelatinase, protease, lipase, pigment and biofilm formation. The results showed the predominance of P. aeruginosa isolates resistance against many of the used antibiotics, with significantly higher mean percent of drug resistant (74.11±7.7) compared to that of Enterobacteriaceae (42.97±9.09). Also, all Pseudomonas isolates were extensively drug resistant (XDR), while Enterobacteriaceae were multi-drug resistance (MDR). Although, most virulence factors were expressed at higher rates in P. aeruginosa than other bacterial species, no relation between the studied virulence factors and antibiotic resistance except for biofilm production, as the results indicated a direct correlation between resistance of antibiotics and the production of biofilm from tested Gram negative bacteria. There was a significant association between biofilm formation and the extensivedrug resistant of Pseudomonas isolates compared to Enterobacteriaceae (P= 0.02).