Biology subjects

Escalante, J.

Publications and source records attributed to Escalante, J..

4 recordsLinked to original sources

bioRxiv2025

Emerging Resistance to Novel -βLactam β-Lactamase Inhibitor Combinations in Klebsiella pneumoniae bearing KPC Variants

BackgroundKlebsiella pneumoniae carbapenemase (KPC) variants, predominantly KPC-2 and KPC-3, are significant global resistance mechanisms. KPC-2 and KPC-3 confer resistance to a broad range of {beta}-lactams, including carbapenems, while remaining susceptible to ceftazidime-avibactam (CZA). Recently, new KPC variants have developed resistance to CZA through mutations, insertions, or deletions in regions such as the {Omega}-loop, 240-loop (237-243 aa), and 270-loop (266-275 aa). This study aimed to investigate the collateral resistance to cefiderocol (FDC) and cefepime/zidebactam (FPZ) among isolates with these mutations. MethodsFifteen clinical isolates of KPC-producing Klebsiella spp. were analyzed, representing 15 distinct variants. Antimicrobial susceptibility testing determined the MICs for CZA, carbapenems, FDC, FPZ, and other antibiotics. Synergy between CZA and FDC was assessed. Whole-genome sequencing (WGS) was used to identify mutations contributing to resistance. ResultsCZA resistance was confirmed in 12 of the 15 KPC variants. Collateral resistance to FDC was observed in eight isolates, with five exhibiting spontaneous resistant subpopulations. Six FDC-resistant strains had mutations in the 270-loop (266-275 aa). Collateral resistance to FPZ was seen in three KPC variants, especially those with mutations in the 270-loop (266-275 aa), though many {Omega}-loop and 240-loop (237-243 aa) mutants remained susceptible. WGS of FDC-resistant subpopulations revealed additional mutations in ompC, rpoC, dksA, and cirA. ConclusionsThis study demonstrates that emerging KPC variants showing resistance to CZA also exhibit resistance to FDC, with collateral resistance to FPZ observed to a lesser extent. Identifying mutations in blaKPC, cirA, and other genes is important to understand resistance mechanisms for effective therapies.

microbiology↗

bioRxiv2023

Fever like temperature impacts on Staphylococcus aureus and Pseudomonas aeruginosa interaction, physiology, and virulence both in vitro and in vivo

BackgroundStaphylococcus aureus and Pseudomonas aeruginosa cause a wide variety of bacterial infections and coinfections, showing a complex interaction that involves the production of different metabolites and metabolic changes. Temperature is a key factor for bacterial survival and virulence and within the host, bacteria could be exposed to an increment in temperature during fever development. We analyzed the previously unexplored effect of fever-like temperatures (39{degrees}C) on S. aureus USA300 and P. aeruginosa PAO1 microaerobic mono- and co-cultures compared with 37{degrees}C, by using RNAseq and physiological assays including in-vivo experiments. ResultsIn general terms both temperature and co-culturing had a strong impact on both PA and SA with the exception of the temperature response of monocultured PA. We studied metabolic and virulence changes on both species. Altered metabolic features at 39{degrees}C included arginine biosynthesis and the periplasmic glucose oxidation in S. aureus and P. aeruginosa monocultures respectively. When PA co-cultures were exposed at 39{degrees}C they upregulated ethanol oxidation related genes along with an increment in organic acid accumulation. Regarding virulence factors, monocultured SA showed an increase in the mRNA expression of the agr operon and hld, pms and pms{beta} genes at 39{degrees}C. Supported by mRNA data, we performed physiological experiments and detected and increment in hemolysis, staphylxantin production and a decrease in biofilm formation at 39{degrees}C. On the side of PA monocultures, we observed increase in extracellular lipase and protease and biofilm formation at 39{degrees}C along with a decrease in motility in correlation with changes observed at mRNA abundance. Additionally, we assessed host-pathogen interaction both in-vitro and in-vivo. S. aureus monocultured at 39{degrees}C showed a decrease in cellular invasion and an increase in IL-8 -but not in IL-6- production by A549 cell line. PA also decreased its cellular invasion when monocultured at 39{degrees}C and did not induce any change in IL-8 or IL-6 production. PA strongly increased cellular invasion when co-cultured at 37{degrees}C and 39{degrees}C. Finally, we observed increased lethality in mice intranasally inoculated with S. aureus monocultures pre-incubated at 39{degrees}C and even higher levels when inoculated with co-cultures. The bacterial burden for P. aeruginosa was higher in liver when the mice were infected with co-cultures previously incubated at 39{degrees}C comparing with 37{degrees}C. ConclusionOur results highlight a relevant change in the virulence of bacterial opportunistic pathogens exposed to fever-like temperatures in presence of competitors, opening new questions related to bacteria-bacteria and host-pathogen interactions and coevolution.

microbiology↗

bioRxiv2022

The Iron Content of Human Serum Albumin Modulates the Susceptibility of Acinetobacter baumannii to Cefiderocol

Mortality rates of patients infected with Acinetobacter baumannii treated with cefiderocol (CFDC) were not as favorable as the best available treatment for pulmonary and bloodstream infections. Previous studies showed that the presence of human serum albumin (HSA) or HSA-containing fluids like human pleural fluid (HPF) or human serum (HS) in the growth medium is correlated with a decrease in the expression of genes associated with high-efficiency iron uptake systems. These observations may explain the less-than-ideal performance of CFDC in pulmonary and bloodstream infections because ferric siderophore transporters enhance penetration of CFDC into the cells cytosol. Removal of HSA from HPF or HS resulted in a reduction of the minimal inhibitory concentration of CFDC. Concomitant with these results, there was an enhancement of the expression of genes associated with high-efficiency iron uptake systems. In addition to inducing modifications in iron-uptake gene expression, removal of HSA also decreased the expression of {beta}-lactam resistance genes. Taken together, these observations indicate that environmental HSA has a role in the expression levels of selected A. baumannii. Furthermore, removal of iron from HSA had the same effect as removal of HSA on the expression of genes associated with high-efficiency iron uptake systems, suggesting that at least one of the mechanisms by which HSA regulates the expression of selected genes is through acting as an iron supplier. IMPORTANCECefiderocol (CFDC) is a new antibiotic that combines its major bactericidal activity, i.e., inhibition of the Gram-negative bacterial cell wall synthesis, with a first in its class mechanism of cell penetration. The siderophore-like moiety facilitates entry through receptors that recognize ferric-siderophore complexes. Recent trials showed that treating pulmonary and bloodstream Acinetobacter baumannii infections with CFDC did not result in the same outcomes as treating other pathogens. Our studies indicated that exposure to human fluids that contain human serum albumin (HSA) increases the MIC values of CFDC. Results described in this work show that HSA is responsible for a reduction in susceptibility of A. baumannii to CFDC. Furthermore, the presence of HSA in the milieu produces a reduction in levels of expression of proteins associated with high-affinity iron uptake systems and enhanced expression of {beta}-lactam resistance-associated genes. Deferration of HSA was accompanied by a loss of the ability to modify these genes expression levels. These results indicate that the microbiological activity of CFDC towards A. baumannii is attenuated in the presence of HSA-containing fluids. This unique insight opens up new avenues of investigation. Understanding this phenomenons molecular mechanism will help define methodologies to increase treatment efficiency.

microbiology↗

bioRxiv2021

Impact of Human Serum Proteins on Susceptibility of Acinetobacter baumannii to Cefiderocol: role of iron transport

Cefiderocol is a siderophore antibiotic that co-opts iron transporters to facilitate cell entry. We show that genes related to iron uptake systems and resistance to {beta}-lactams in Acinetobacter baumannii have altered expression levels in the presence of human serum, human serum albumin, or human pleural fluid. Cefiderocol MICs are also raised in the presence of the mentioned fluids. Clinical response in A. baumannii infections may be related to the interplay of these human factors.

microbiology↗