Objectives: Acinetobacter Baumannii is an opportunistic nosocomial pathogen belonging to the Moraxellaceae family. The emergence of multidrug resistant strains of this pathogen caused many problems for hospitals and patients. The aim of the current study was to isolate, identify, and morphologically, physiologically, and in vivo analyze a new lytic bacteriophage targeting extensively drug‐resistant (XDR) A. baumannii.Materials and Methods: Different wastewater samples were tested for isolation of lytic bacteriophage against 19 A. baumannii isolates obtained from patients hospitalized in a hospital in Arak, Iran, from January 2019 to March 2019. The phenotypic and genotypic characteristics of A. baumannii strains (resistance genes including: adeA, adeB, adeC, adeR, adeS, ISAba1, blaOXA‐23, blaOXA‐24) were analyzed. The isolated phage characteristics including adsorption time, pH and thermal stability, host range, one‐step growth rate, electron microscopy examination, and therapeutic efficacy of the phage were also investigated. Therapeutic efficacy of the phage was evaluated in a rat model with burn infection of XDR A. baumannii. The lesion image was taken on different days after burning and infection induction and was compared with phage untreated lesions.Results: The results showed unique characteristics of the isolated phage (vB‐AbauM‐Arak1) including high specificity for Acinetobacter baumannii, stability at a relatively wide range of temperatures and pH values, short adsorption time, short latent period, and large burst size. In relation to the therapeutic efficacy of the phage, the lesion area decreased in phage‐treated groups over 14 days than in those untreated, significantly (p < 0.05).Conclusion: Our findings demonstrated that isolated lytic phage was able to eliminate burn infections caused by XDR A. baumannii in a rat model. So, it may be recommended as alternative options toward to developing a treatment for extensively drug resistant Acinetobacter infections.

Shigella spp. are water‐borne pathogens responsible for mild to severe cases bacilli dysentery all around the world known as Shigellosis. The progressively increasing of antibiotic resistance among Shigella calls for developing and establishing novel alternative therapeutic methods. The present study aimed to evaluate a novel phage cocktail of lytic phages against Extended Spectrum Beta Lactamase (ESBL) isolates of Shigella species in an aquatic environment. The phage cocktail containing six novel Shigella specific phages showed a broad host spectrum. The cocktail was very stable in aquatic environment. .The cocktail resulted in about 99% decrease in the bacterial counts in the contaminated water by several species and strains of Shigella such as S. sonnei, S. flexneri, S. dysenteriae. Achieving such a high efficiency in this in‐vitro study demonstrates a high potential for in‐vivo and in‐situ application of this phage cocktail as a bio‐controlling agent against Shigella spp. contamination and infections.

Background: Approximately 80% of nosocomial infections are caused by strains of Klebsiella pneumoniae. Resistance to β-lactam antibiotics is a result of expression of extended-spectrum β-lactamase (ESBL) genes. Recently, phage therapy has gained increasing attention due to its many advantages over chemotherapy. Objectives: The aim of this study was to isolate ESBL-positive Klebsiella pneumoniae strains from different types of wounds, and a lytic bacteriophage against them. Methods: During a two-year period from January 2013 to February 2015, in a cross-sectional study, 41 K. pneumoniae strains were isolated from 193 categories of infected wounds at three hospitals in Isfahan, Iran. Phenotypic and genotypic methods were used to detect the ESBL-positive strains. A lytic phage against K. pneumoniae was isolated, and its host range, morphology, thermal and pH stability, saline stress, and estimated genome size were determined. Results: Of the 41 K. pneumoniae isolates, 18 were ESBL-producing and 36 carried antibiotic-resistance genes. A total of 36 out of 41 isolated samples carried one or more resistance genes. The results showed that the differences between phenotypic and genotypic identification methods were significant (P = 0.0001). The SHV, CTX-M, and TEM genes were detected in 29, 10, and 9 isolates of the tested bacteria, respectively. No bacteria contained both the SHV and the CTX-M genes. The frequency of the SHV gene was significantly higher than that of the other genes (P = 0.0001). The phage’s morphology features placed it in the Myoviridae family. Only 38 out of 41 clinical isolates were susceptible to the phage. Phage titers were completely preserved after one hour of incubation at 30°C and 40°C, and they were stable at different pH values. The phage’s survival decreased when the salt concentration was increased. Conclusions: The high rate of isolation of antibiotic-resistant strains of K. pneumoniae was consistent with other studies. As the phage was virulent and specific for K. pneumoniae, and was stable and active at different pH values, salt concentrations, and temperatures, its application in phage therapy of infected wounds is suggested. Keywords: Antibiotic Resistance; Bacteriophage; Klebsiella pneumoniae