Exploring lytic bacteriophages as alternatives for combating multi drug-resistant Acinetobacter baumannii

Abstract

Multi-Drug Resistant (MDR) Acinetobacter baumannii (A. baumannii) is a serious threat to human health worldwide typically due to its resistance to a wide variety of major classes of antibiotics. It is associated with infections such as pneumonia, septicemia, meningitis, urinary tract and wound infections. The application of bacteriophages is a potential tool for controlling MDR A. baumannii infections. This study, carried out between the period of December/2023 and March/2024 aimed at exploring lytic bacteriophages(phages) as alternatives for combating MDR A. baumannii infections. The double-agar overlay method and spot assay techniques were used to isolate and characterize phages against MDR A. baumannii. Presence of phages was determined by the plaques appearance, diameter, turbidity and the presence of a halo in the culture media. Furthermore, phage characterization in terms of host range, growth characteristics and stability under various conditions of temperature and pH was carried out. One lytic A.baumannii phage (designated AP01) was isolated from hospital waste water. The phage AP01 exhibited lytic activity on three of the available Acinetobacter species isolates tested against, and it was unable to infect other genera that were used in this study (Staphylococcus aureus, Escherichia coli, Streptococcus pyogenes, Klebsiella pneumoniae and Proteus vulgaris). Phage AP01 reached the maximum activity at neutral pH of 7 and temperature of 37 ºC with no activity observed at temperatures above 50ºC. From the one-step growth curve experiments, the latent period was 30minutes, and the burst size was approximately 257 PFU per infected cell. Overall, AP01 can be a potential candidate for control of MDR A.baumannii infections. However, more phages and further characterization needs to be done in order to get strains for preparation of phage cocktails for management of MDR A.baumannii infections.