Molecular detection of antibiotics profile of Citrobacter freundii which isolated from burn and wound infection

This study aims to contribute to clinical treatment strategies by analyzing the antibiotic resistance profile of Citrobacter freundii strains isolated from burn and wound infections by molecular and phenotypic methods. Citrobacter freundii is an important opportunistic pathogen that causes nosocomial infections especially in immunocompromised patients and can develop multidrug resistance. In this study, samples from 200 burn and wound infection patients admitted to Imam Sadiq Teaching Hospital in Babil Province of Iraq were evaluated and Citrobacter freundii was isolated from 60 (30%) of them. Of the isolates, 66.7% (40 samples) were from burns and 33.3% (20 samples) were from wounds. Antibiotic susceptibilities of the isolates were tested by disk diffusion and minimum inhibitory concentration (MIC) methods. The antibiotics tested included Piperacillin/Tazobactam, Cefazolin, Ceftazidime, Cefepime, Imipenem, Amikacin, Gentamicin, Ciprofloxacin, Levofloxacin and Tigecycline. According to the results, 85% of the isolates were resistant to Cefazolin, 35% to Ceftazidime, 20% to Cefepime and 5% to Imipenem. Although carbapenem resistance was low, carbapenemase production was detected in three isolates carrying blaNDM-1 and blaKPC-3 genes. Furthermore, 65% of the isolates had a broad-spectrum beta-lactamase (ESBL) and 40% had the qnrB quinolone resistance gene. Molecular analyses revealed genetic profiles compatible with biochemical features such as citrate utilization in 88% of the isolates and H₂S production in 95%. Gene screening by PCR confirmed the presence of resistance genes such as TetB (30%), Erna (25%) and PIP (15%). Statistical analysis showed that burn isolates carried a higher proportion of β-lactam resistance genes compared to wound isolates (p<0.05). This study emphasizes that Citrobacter freundii has developed multiple resistance mechanisms, especially in hospital settings, and has become resistant to many antibiotics other than carbapenems. The results reveal the importance of increasing infection control measures, implementing antimicrobial stewardship programs and molecular monitoring of resistance genes.