Antimicrobial Susceptibility Pattern and Virulence Genes Detection in Citrobacter freundii Isolated from Patients of a Tertiary Care Hospital, Bangladesh

Background: Citrobacter freundii is an infrequent hospital acquired pathogen to cause different types of disease in clinical settings. This pathogen is associated with wide range of infections causing unpredictably high mortality rate of 30-60%.  Separation of this pathogen in health care settings is escalating and multidrug resistant strains are emerging. Therefore, this study aimed to detect antimicrobial resistance pattern and virulence genes among the isolated C. freundii. Methods: A total 500 samples (urine, stool, wound swab & pus, blood endotracheal aspirates and sputum) from patients with clinically suspected infections irrespective of age and sex were used in this study. Disc diffusion method was used to detect susceptibility pattern of antibiotics; colistin, tigecycline and fosfomycin susceptibility pattern was identified by minimum inhibitory concentration (MIC) method. Polymerase chain reaction (PCR) was done to detect potential virulence genes. Results: Among 27 isolated C. freundii, majority were resistant to amoxiclav (92.59%), trimethoprim-sulfomethoxazole (88.89%), cefotaxime and ceftazidime (85.19%) followed by ceftriaxone (81.48%), cefepime and ciprofloxacin (77.78%). MIC showed least resistance to colistin (29.63%), fosfomycin (11.11%) and tigecycline (7.41%). PCR was positive for via B gene (48.15%)   and lt-A gene (25.93%). hly A, lt, lt-h genes showed negative results. Conclusion: Antibiotic resistance found in this study is quite worrisome as widespread resistance is seen among the bacteria isolated from human infection. Also, virulence genes play important role in C. freundii infection.