Abstract
Acinetobacter baumannii is a gram-negative, non-fermenting aerobic bacterium which is often associated with hospital-acquired infections and known for its ability to develop resistance to antibiotics, form biofilms, and survive for long periods in hospital environments. In this study, we present two novel viruses, vB_AbaP_AS11 and vB_AbaP_AS12, specifically infecting and lysing distinct multidrug-resistant clinical A. baumannii strains with K19 and K27 capsular polysaccharide structures, respectively. Both phages demonstrate rapid adsorption, short latent periods, and high burst sizes in one-step growth experiments. The AS11 and AS12 linear double-stranded DNA genomes of 41,642 base pairs (bp) and 41,402 bp share 86% nucleotide sequence identity with the most variable regions falling in host receptor–recognition genes. These genes encode tail spikes possessing depolymerizing activities towards corresponding capsular polysaccharides which are the primary bacterial receptors. We described AS11 and AS12 genome organization and discuss the possible regulation of transcription. The overall genomic architecture and gene homology analyses showed that the phages are new representatives of the recently designated Fri1virus genus of the Autographivirinae subfamily within the Podoviridae family.
Highlights
The emergence and rapid spread of multidrug-resistant (MDR) and extensively drug-resistant (XDR) bacterial pathogens in medical practice necessitates the introduction of alternative methods of controlling antibiotic-resistant bacterial infections
Susceptibility testing of A. baumannii isolates to ceftazidime, cefepime, imipenem, meropenem, sulbactam, gentamicin, amikacin, ciprofloxacin, levofloxacin, colistin, tigecycline and trimethoprim-sulfamethoxazole was performed by the reference broth microdilution method according to ISO 20776-1:2006; the results were interpreted according to EUCAST clinical breakpoints, v. 6.0
PCR fragments corresponding to the predicted transcription start area were synthesized from AS11 and AS12 DNA
Summary
The emergence and rapid spread of multidrug-resistant (MDR) and extensively drug-resistant (XDR) bacterial pathogens in medical practice necessitates the introduction of alternative methods of controlling antibiotic-resistant bacterial infections. This is especially pertinent for pathogens causing nosocomial infections, such as Acinetobacter baumannii, a gram-negative, non-fermenting aerobic bacterium. This microorganism has, over the years, acquired resistance to most currently available antibiotics, disinfectants and antiseptics, tolerance to detergents, ultraviolet radiation, desiccation, and the ability to form biofilms on various biotic and abiotic surfaces [1]. We present a characterization of two podoviruses, AS11 and AS12, novel members of the genus Fri1virus (named after the podophage Fri1) recently designated by the International Committee on Taxonomy of Viruses (ICTV) [9], and compare them to related phages
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