Biology subjects

McCarthy, R. R.

Publications and source records attributed to McCarthy, R. R..

4 recordsLinked to original sources

bioRxiv2024

Using Galleria mellonella to study pathogen dissemination and anti-infective surface coatings.

Hospital associated infections and localised hospital outbreaks are a major challenge for infection control teams (ICTs) in hospitals around the world. Advances in artificial intelligence and infection modelling have enabled ICT teams to better predict and trace infection spread. However, it is notoriously difficult to replicate bacterial dissemination or validate prediction models in a laboratory setting due to a lack of effective in vivo models. In this work, we sought to develop Galleria mellonella as a model organism to replicate the dissemination of pathogens in a hospital intensive care unit (ICU). By combining this model organism with 3D printed models of a real hospital ICU, we are able to demonstrate that larvae do disseminate the multidrug resistant pathogen Acinetobacter baumannii within this ICU model and that it is possible to use this model to identify infection hotspots. Importantly, this model can also be used for intervention strategy testing as we also show that bacterial dissemination can be significantly mitigated by the introduction of antimicrobial wall surface coatings. This model provides a robust platform for the testing of antimicrobial surface coatings as well as the study of genetic determinants with a role in pathogen dissemination.

microbiology↗

bioRxiv2023

Antibiotic potentiation and inhibition of cross-resistance in pathogens associated with cystic fibrosis

Critical Gram-negative pathogens, like Pseudomonas, Stenotrophomonas and Burkholderia, have become resistant to most antibiotics. Complex resistance profiles together with synergistic interactions between these organisms increase the likelihood of treatment failure in distinct infection settings, for example in the lungs of cystic fibrosis (CF) patients. Here, we discover that cell envelope protein homeostasis pathways underpin both antibiotic resistance and cross-protection in CF-associated bacteria. We find that inhibition of oxidative protein folding inactivates multiple species-specific resistance proteins. Using this strategy, we sensitize multidrug-resistant Pseudomonas aeruginosa to {beta}-lactam antibiotics and demonstrate promise of new treatment avenues for the recalcitrant emerging pathogen Stenotrophomonas maltophilia. The same approach also inhibits cross-protection between resistant S. maltophilia and susceptible P. aeruginosa, allowing eradication of both commonly co-occurring CF-associated organisms. Our results provide the basis for the development of next-generation strategies that target antibiotic resistance, while also impairing specific interbacterial interactions that enhance the severity of polymicrobial infections.

microbiology↗

bioRxiv2022

A high-efficiency scar-free genome editing toolkit for Acinetobacter baumannii

Structured synopsisO_ST_ABSBackgroundC_ST_ABSThe current mutagenesis tools for Acinetobacter baumannii leave selection markers or residual sequences behind, or involve tedious counterselection and screening steps. Furthermore, they are usually adapted for model strains, rather than to multidrug resistant (MDR) clinical isolates. ObjectivesTo develop a scar-free genome editing tool suitable for chromosomal and plasmid modifications in MDR A. baumannii AB5075. MethodsWe prove the efficiency of our adapted genome editing system by deleting the multidrug efflux pumps craA and cmlA5, as well as curing plasmid p1AB5075. We then characterised the antibiotic sensitivity phenotype of the mutants compared to the wild type for chloramphenicol, tobramycin and amikacin by disc diffusion assays and determined their minimum inhibitory concentration for each strain. ResultsWe successfully adapted the genome editing protocol to A. baumannii AB5075, achieving a double recombination frequency close to 100% and securing the construction of a mutant within 10 work days. Furthermore, we show that the {Delta}craA has a strong sensitivity to chloramphenicol, tobramycin and amikacin, whereas the {Delta}cmlA5 mutant does not show a significant decrease in viability for the antibiotics tested. On the other hand, the removal of p1AB5075 produced an increased sensitivity to tobramycin and amikacin. ConclusionWe have adapted a highly efficient genome editing tool for A. baumannii and proved that craA has a broader substrate range than previously thought. On the other hand, whereas cmlA5 is annotated as a chloramphenicol efflux pump and is encoded within an aminoglycoside resistance island, it does not provide resistance to any of those compounds.

microbiology↗

bioRxiv2021

Breaking antimicrobial resistance by disrupting extracytoplasmic protein folding

Antimicrobial resistance in Gram-negative bacteria is one of the greatest threats to global health. New antibacterial strategies are urgently needed, and the development of antibiotic adjuvants that either neutralize resistance proteins or compromise the integrity of the cell envelope is of ever-growing interest. Most available adjuvants are only effective against specific resistance proteins. Here we demonstrate that disruption of cell envelope protein homeostasis simultaneously compromises several classes of resistance determinants. In particular, we find that impairing DsbA-mediated disulfide bond formation incapacitates diverse {beta}-lactamases and destabilizes mobile colistin resistance enzymes. Furthermore, we show that chemical inhibition of DsbA sensitizes multidrug-resistant clinical isolates to existing antibiotics and that the absence of DsbA, in combination with antibiotic treatment, substantially increases the survival of Galleria mellonella larvae infected with multidrug- resistant Pseudomonas aeruginosa. This work lays the foundation for the development of novel antibiotic adjuvants that function as broad-acting resistance breakers. IMPACT STATEMENTDisruption of disulfide bond formation sensitizes resistant Gram- negative bacteria expressing {beta}-lactamases and mobile colistin resistance enzymes to currently available antibiotics.

microbiology↗