Experimental Phage Evolution Results in Expanded Host Ranges Against MDR and XDRKlebsiella pneumoniaeIsolates
Authors: Ghatbale Pooja , Blanc Alisha , Leonard Jesse , Bates Monica , Garcia Andrew , Hensley Joshua , Nunes Danielle Devequi Gomes , Hitchcock Nicole , Shiach Job , Bardaró Roberto , Sah Govind , Ghose Chandrabali , Whiteson Katrine , Schooley Robert , White Richard Allen , Cobián Güemes Ana G. , Meyer Justin R. , Pride David T. 
Published: December 2024

Resistance to antibiotics is approaching crisis levels for organisms such as the ESKAPEE pathogens (includesEnterococcus faecium,Staphylococcus aureus,Klebsiella pneumoniae,Acinetobacter baumannii,Pseudomonas aeruginosa,Enterobacterspp., andEscherichia coli) that often are acquired in hospitals. These organisms sometimes have acquired plasmids that confer resistance to most if not all beta-lactam antibiotics such as those produced by Carbapenem Resistant Enterobacterales (CREs). We have been developing alternative means for dealing with antibiotic resistant microbes that cause infections in humans by developing viruses (bacteriophages) that attack and kill them. We have been working with one of the ESKAPEE pathogens,K. pneumoniae, that has one of the highest propensities for antimicrobial resistance, to develop phages that target and kill it. We identified a number of phages that have lytic capacity against only a few clinical isolates, and through experimental evolution over the course of 30 days, were able to vastly expand the host ranges of these phages to kill a broader range of clinicalK. pneumoniaeisolates including MDR (multi-drug resistant) and XDR (extensively-drug resistant) isolates. Most interestingly, they were capable of inhibiting growth of clinical isolates both on solid and in liquid medium over extended periods. That we were able to extend the host ranges of multiple naïve MDR and XDRK. pneumoniaethrough experimental phage evolution suggests that such a technique may be applicable to other antibiotic-resistant organisms to help stem the tide of antibiotic resistance and offer further options for medical treatments.

Importance

Bacterial pathogens are becoming greater threats given the rise in antibiotic resistance, where traditional therapies may no longer work to cure some infections. Chief amongst these multidrug resistant infections (MDR) and extensively drug-resistant infections (XDR) isKlebsiella pneumoniae, which is known to sometimes harbor genetic elements that render it incredibly difficult to treat with conventional antibiotics. Treatments like bacteriophages have not had much success against such pathogens because resistance to the phages used often develops rapidly. We adapted a co-evolutionary technique to developK. pneumoniaephages to be highly active longitudinally againstK. pneumoniaeclinical isolates. In as few as 30 days, we were able to vastly expand the host ranges ofK. pneumoniaephages against MDR and XDR clinical isolates and that maintain their infectivity over clinically relevant time periods. By adapting these established techniques to clinical MDR and XDRK. pneumoniaeisolates, we believe we can establish similar techniques for expanding phage host ranges against most antibiotic-resistant bacteria. As such, phages can be viable alternatives to antibiotics when antibiotic resistance exists in hospitals and communities.