en Microbiology Original Article Original Article <div style="text-align: justify;"><strong>Background</strong>: During the COVID-19 pandemic, the excessive use of antibiotics to manage co-infections and reduce mortality rates may have contributed to the increase in antimicrobial resistance.&nbsp;<br> <strong>Objectives</strong>: This research was conducted to evaluate the antibiotic resistance patterns of multidrug-resistant (MDR) Pseudomonas aeruginosa strains during the COVID-19 pandemic in North Iran.&nbsp;<br> <strong>Methods</strong>: This cross-sectional research was conducted at four teaching hospitals in Sari, Iran between May 2022 and June 2023. The macro dilution broth technique was employed to determine the minimum inhibitory concentration (MIC). All isolates were screened using the multiplex polymerase chain reaction (PCR) method for blaAmpC, blaCTX, blaSHV, blaSIM, blaSPM, blaIMP, and also virulence genes, including TOXA and ExoS.&nbsp;<br> <strong>Results</strong>: The antibiotics co-amoxiclav and gentamicin showed the least activity in terms of MIC50 values, while meropenem exhibited the most potent activity based on the geometric mean of minimum inhibitory concentration (GM MIC) values. The multiplex PCR method revealed that all isolates possessed the ExoS toxin gene, while the ExoA gene was not detected. The observed frequencies of resistance genes were blaSHV (91.3%), blaCTX-M (76%), blaAmpC (91.3%), and blaIMP (95.2%). The blaSPM and blaSIM genes were not distinguished.&nbsp;<br> <strong>Conclusions</strong>: This research recommends piperacillin/tazobactam and meropenem for the treatment of multi-drug-resistant P. aeruginosa infections.&nbsp;</div> COVID-19, Drug resistance, Pseudomonas aeruginosa, Healthcare associated infections, Multiplex polymerase chain reaction (PCR) 273 282 http://jpr.mazums.ac.ir/browse.php?a_code=A-10-369-6&slc_lang=en&sid=1 Fatemeh Hosseinzadeh fatima.hzade@gmail.com 100319475328460011688 100319475328460011688 No Pediatric Infectious Diseases Research Center, Communicable Diseases Institute, Mazandaran University of Medical Sciences, Sari, Iran. Golnar Rahimzadeh rahimzadehgolnar@yahoo.com 100319475328460011689 100319475328460011689 No Pediatric Infectious Diseases Research Center, Communicable Diseases Institute, Mazandaran University of Medical Sciences, Sari, Iran. Fatemeh Ahangarkani fkani63@gmail.com 100319475328460011690 100319475328460011690 No Antimicrobial Resistance Research Center, Communicable Diseases Institute, Mazandaran University of Medical Sciences, Sari, Iran. Seyedeh Mahsa Salehpour mahsa.salehpour95@gmail.com 100319475328460011691 100319475328460011691 No Students Research Committee, Mazandaran University of Medical Sciences, Sari, Iran. Shaghayegh Rezai rezai.shaghayegh1992@gmail.com 100319475328460011692 100319475328460011692 No Department of Medical Microbiology and Virology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran. Reza Valadan valadan.reza@gmail.com 100319475328460011693 100319475328460011693 No Molecular and Cell Biology Research Center, Mazandaran University of Medical Sciences, Sari, Iran. Laleh Vahedi lalevahedi@gmail.com 100319475328460011694 100319475328460011694 No Department of Pathology, Faculty of Medicine, Mazandaran University of Medical Sciences, Sari, Iran. Somayeh Sheidaei s.sheidaie2015@yahoo.com 100319475328460011695 100319475328460011695 No Department of Pathology, Faculty of Medicine, Mazandaran University of Medical Sciences, Sari, Iran. Faezeh Sadat Movahedi f.movahedi69@gmail.com 100319475328460011696 100319475328460011696 No Pediatric Infectious Diseases Research Center, Communicable Diseases Institute, Mazandaran University of Medical Sciences, Sari, Iran. Raha Rezai grahimzadeh@mazums.ac.ir 100319475328460011697 0009-0005-1039-591X No Pediatric Infectious Diseases Research Center, Communicable Diseases Institute, Mazandaran University of Medical Sciences, Sari, Iran. Mohammad Sadegh Rezai drmsrezaii@yahoo.com 100319475328460011698 100319475328460011698 Yes Pediatric Infectious Diseases Research Center, Communicable Diseases Institute, Mazandaran University of Medical Sciences, Sari, Iran.