Background Widespread misuse of antibiotics caused bacterial resistance increasingly become a serious threat. Bacteriophage therapy promises alternative treatment strategies for combatting drug-resistant bacterial infections. In this study, we isolated and characterized a novel, potent lytic bacteriophage against multi-drug resistant (MDR) Acinetobacter baumannii and described the lytic capability and endolysin activity of the phage to evaluate the potential in phage therapy. Methods A novel phage, pIsf-AB02, was isolated from hospital sewage. The morphological analysis, its host range, growth characteristics, stability under various conditions, genomic restriction pattern were systematically investigated. The protein pattern of the phage was analyzed, and the endolysin activity of the phage was determined under the non-denaturing condition on SDS-PAGE. The optimal lytic titer of phage was assessed by co-culture of the phage with clinical MDR A. baumannii isolates. Finally, HeLa cells were used to examine the safety of the phage. Results The morphological analysis revealed that the pIsf-AB02 phage displays morphology resembling the Myoviridae family. It can quickly destroy 56.3% (27/48) of clinical MDR A. baumannii isolates. This virulent phage could decrease the bacterial host cells (from 108 CFU/ml to 103 CFU/ml) in 30 min. The optimum stability of the phage was observed at 37 °C. pH 7 is the most suitable condition to maintain phage stability. The 15 kDa protein encoded by pIsf-AB02 was detected to have endolysin activity. pIsf-AB02 did not show cytotoxicity to HeLa cells, and it can save HeLa cells from A. baumannii infection. Conclusion In this study, we isolated a novel lytic MDR A. baumannii bacteriophage, pIsf-AB02. This phage showed suitable stability at different temperatures and pHs, and demonstrated potent in vitro endolysin activity. pIsf-AB02 may be a good candidate as a therapeutic agent to control nosocomial infections caused by MDR A. baumannii.

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Objective: Acinetobacter baumannii is responsible for most nosocomial infections in hospitals. It has the ability to form bio lms and has a high degree of antibiotic resistance. Colistin is one of the last therapeutic options for the treatment of Multi Drug Resistance infections. Recently, strains of this pathogen resistance to the colistin were reported increasingly. Therefore, alternative antibacterial methods such as phage therapy are being researched.Results: From 15 MDR A. baumannii clinical isolates, 26.6% were resistant to colistin, 80% were able to produce strong bio lm, and 20% produce weak bio lm. The isolated lytic phage (IsfAB78) was able to reduce the bio lm by up to 87%. Since most of the MDR colistin-resistant strains produce bio lm, and MDR A. baumannii infections are di cult to treat, development of phage therapy could be an alternative in the future. Phage IsfAB78 is a good candidate for this purpose.

Objective: Acinetobacter baumannii is responsible for most nosocomial infections in hospitals. It has the ability to form biofilms and has a high degree of antibiotic resistance. Colistin is one of the last therapeutic options for the treatment of Multi Drug Resistance infections. Recently, strains of this pathogen resistance to the colistin were reported increasingly. Therefore, alternative antibacterial methods such as phage therapy are being researched. Results: From 15 MDR A. baumannii clinical isolates, 26.6% were resistant to colistin, 80% were able to produce strong biofilm, and 20% produce weak biofilm. The isolated lytic phage (IsfAB78) was able to reduce the biofilm by up to 87%. Since most of the MDR colistin-resistant strains produce biofilm, and MDR A. baumannii infections are difficult to treat, development of phage therapy could be an alternative in the future. Phage IsfAB78 is a good candidate for this purpose.

Background: Acinetobacter baumannii is a major pathogen in the hospital, especially in Intensive Care Units (ICU) and the resistance to multiple drugs as a major contributor to hospital infection. Bacteriophages are viruses that attack bacteria and kill them that could be used for clinical treatment. The aim of the study is in evaluating the function of bacteriophage specificity of multi-drug resistant Acinetobacter baumannii, to be used as a useful method for treating of Acinetobacter Infections.Methods: Cross-sectional study during the year 2017, from patients admitted to the ICU, First, 48 isolates of Acinetobacter baumannii were identified by phenotypic method and amplified with blaOXA-51 gene. Then, the sensitivity of phages to pathogens namely ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumonia, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp) evaluated. DNA of the phage was extracted using the Viral Nucleic Extraction Kit II (Geneaid, Taipei, Taiwan) according to the manufacturer's instructions. Then for protein analysis, PEG-precipitated purified phages were subjected directly to SDS-PAGE, and protein bands were visualized by coomassie Blue G-250 staining method. Finally for cell survival assay we investigated the toxicity of the isolated phage to Hela cells.Results: In the bacterial resistance pattern, the highest resistance belongs to ciprofloxacin. In optimal phage test, at dilution of 1 (MOI 1) it produced the best effect on bacteria in 30 minutes. Phage sensitivity to different hosts performed by double layer agar method, the phage was treated with ESKAPE bacteria and after 24 hours’ incubation at 37°C, only for Acinetobacter baumannii Plaque created. The genome analysis indicated that phage pIsf-AB2 has a double-stranded DNA genome. In bacterial control, all cells were killed by A. baumannii, and no live-cell was seen. The cells remained in control of the phage, and the phage did not affect the cells.Conclusion: Our findings support the potential application of the phage with potent endolysin activity against MDR A. baumannii and give useful information for its further study and use.