en ميکروبيولوژي Microbiology پژوهشي Research <div style="text-align: justify;"><strong>Background</strong>: Acinetobacter baumannii is an opportunistic gram-negative pathogen frequently associated with severe nosocomial infections and increasing multidrug resistance (MDR). This study aimed to compare the diagnostic performance of culture and PCR-based molecular methods targeting the blaOXA-51-like gene for the detection of A. baumannii and to evaluate the antibiotic resistance patterns of isolates obtained from respiratory samples.<br> <strong>Materials and Methods</strong>: In this descriptive cross-sectional study, 236 patients with respiratory illnesses who were admitted to tertiary care hospitals in Karaj, Iran, during 2019 were enrolled. Bronchoalveolar lavage (BAL) and induced sputum samples were collected. Bacterial culture and antimicrobial susceptibility testing (AST) were performed according to Clinical and Laboratory Standards Institute (CLSI) guidelines, and polymerase chain reaction (PCR) assays were carried out using species-specific primers. Statistical analyses, including McNemar&rsquo;s test, were conducted using SPSS software, version 19.<br> <strong>Results</strong>: PCR detected A. baumannii in 75 samples (31.8%), while culture identified 70 samples (29.7%). PCR showed significantly higher sensitivity and specificity compared to culture (P<0.05). Antibiotic susceptibility testing revealed 100% resistance to ceftazidime, gentamicin, tobramycin, imipenem, ciprofloxacin, amikacin, cefepime, piperacillin, cefotaxime, ceftriaxone, piperacillin&ndash;tazobactam, doxycycline, tetracycline, and trimethoprim&ndash;sulfamethoxazole.<br> <strong>Conclusion</strong>: PCR demonstrated superior diagnostic accuracy compared to conventional culture for detecting A. baumannii in respiratory samples. The universal resistance observed underscores the urgent need for continuous surveillance, strict infection control measures, and the implementation of rapid molecular diagnostics to guide appropriate antimicrobial therapy in hospital settings.</div> Acinetobacter baumannii, Antibiotic resistance, Molecular detection, Polymerase chain reaction (PCR), Nosocomial infection 31 38 http://rmm.mazums.ac.ir/browse.php?a_code=A-10-1395-1&slc_lang=en&sid=1 Hamid Reza Farzaneh hamidrezafarzaneh1111@gmail.com 100319475328460013365 100319475328460013365 Yes Aramis Laboratory, Rasht, Iran. Saba Soufi Sabasoufi2@gmail.com 100319475328460013366 100319475328460013366 No Department of Microbiology, Ka.C., Islamic Azad University, Karaj, Iran. Ali Ahmadi aliahmadi.g.u.m@gmail.com 100319475328460013367 100319475328460013367 No Department of Genetics, TeMS.C., Islamic Azad University, Tehran, Iran. Nemat Karimi Karimi.neamat@gmail.com 100319475328460013368 100319475328460013368 No Department of Microbiology, Ka.C., Islamic Azad University, Karaj, Iran. Maryam Rahmani maryamrahmani76104@gmail.com 100319475328460013369 100319475328460013369 No Department of Microbiology, Ro.C., Islamic Azad University, Roudehen, Iran.