چكيده لاتين
Enterobacter is a facultative anaerobic, Gram-negative rod-shaped bacterium classified within the Enterobacteriaceae family. The strain Enterobacter cloacae subsp. cloacae is an opportunistic pathogen responsible for various nosocomial and community-acquired infections, including bacteremia, pneumonia, urinary tract, lower respiratory tract, wound, and intra-abdominal infections. This bacterium is frequently associated with burn wounds, immunocompromised patients, cancer patients, and neonates in intensive care units. By forming biofilms, E. cloacae demonstrates the ability to colonize medical devices and equipment. Antibiotic resistance in bacteria poses a significant health threat, emphasizing the urgent need for alternative therapies. Bacteriophages, due to their specificity, biosafety, and other advantages, offer an effective strategy to combat antibiotic-resistant bacterial infections and reduce the simultaneous use of multiple antibiotics. In this study, samples were collected from August to November 2024 from urban wastewater, hospital effluent, livestock wastewater, pond water, and the Zayandeh rud River in Isfahan to isolate a lytic bacteriophage against E. cloacae. The isolated phage was characterized in terms of its morphology, host range, stability under environmental stresses (pH, UV, temperature, and salinity), adsorption time, one-step growth curve, biofilm reduction or elimination ability, and its effects on the survival of Galleria mellonella larvae. The isolated lytic phage targeting E. cloacae belonged to the class Caudoviricetes based on its morphological characteristics. This phage exhibited high stability across a temperature range of -20°C to 70°C, a pH range of 3 to 12, sodium chloride concentrations of 1% to 30%, and UV irradiation at 254 nm for 120 minutes. The adsorption rate of the phage to the host bacterium was approximately 42% and 67% after 2 minutes in the presence of magnesium and calcium ions, respectively. Maximum adsorption occurred after 30 minutes for calcium ions and 15 minutes for magnesium ions, with rates of approximately 75% and 82%, respectively. The latent period of the phage was 10 minutes, with a short burst time of 15 minutes, producing approximately 150 virions per bacterial cell. The optimal multiplicity of infection for the phage against E. cloacae was determined to be 0.1. Furthermore, the isolated phage demonstrated significant efficacy in reducing or eliminating E. cloacae biofilm. It also exhibited promising results in pre-treatment, post-treatment, and Co- treatment models during G. mellonella larvae survival assays. Based on the findings of this study, the isolated phage has potential applications in E. cloacae phage therapy, addressing antibiotic resistance, biofilm elimination, and biocontrol of this bacterium.
