comprehensive analysis of antibiotic resistance patterns in clinical isolates of acinetobacter baumannii: a cross-sectional study in karaj, iran (2019)

Background: 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.materials and methods: 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's test, were conducted using spss software, version 19.results: 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–tazobactam, doxycycline, tetracycline, and trimethoprim–sulfamethoxazole.conclusion: 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.