Biology subjects

Lopez-Causape, C.

Publications and source records attributed to Lopez-Causape, C..

6 recordsLinked to original sources

bioRxiv2025

Identification and Functional Insights into New Phage Tail-Like Bacteriocins (PTLBs) Targeting Pseudomonas aeruginosa as new antimicrobials

The current health crisis caused by multidrug resistant (MDR) pathogens is one of the health problems of most concern globally. Infections caused by these pathogens, such as Pseudomonas aeruginosa, lead to high rates of complications, particularly in compromised patients such as cystic fibrosis (CF) patients. The need to counteract and minimize the forecast future impact has led to the rescue of phage therapy. The use of bacteriophages has important advantages, including highly specific targeting, self-amplification at the infection site, minimal disruption of the microbiome, safety and biocompatibility. However, the capacity of bacteria to escape these entities results in a form of resistance that compromises the effectiveness of the therapy. This involves the search for potential alternatives, such as the phage tail-like bacteriocins (PTLBs), also named as tailocins. These high molecular weight particles resemble the tail structure of bacteriophages and are characterized by the absence of genetic material, avoiding the development of resistance, one of the major handicaps associated with phage therapy. In this study, we detected 34 different PTLBs in 75 P. aeruginosa genomes, with different serotypes and sequence types, 11 of which were characterized as novel F-type PTLBs subtypes (F13-F24). Furthermore, we report that four selected PTLBs (R1, F15, F19, R3-F24) can deal with bacterial infection, with the R1 and the F15 PTLBs being the most efficient in clearing infection in vitro, yielding a survival rate of more than 75% in the Galleria mellonella larvae in vivo model. This reaffirms the potential of PTLBs to control P. aeruginosa infections, which can cause chronic infections in some patients, such as people with CF, due to its strong impact as a MDR bacterium. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=194 HEIGHT=200 SRC="FIGDIR/small/671207v1_ufig1.gif" ALT="Figure 1"> View larger version (34K): org.highwire.dtl.DTLVardef@76b60borg.highwire.dtl.DTLVardef@1a9cd0aorg.highwire.dtl.DTLVardef@d45dd0org.highwire.dtl.DTLVardef@5b345a_HPS_FORMAT_FIGEXP M_FIG C_FIG HIGHLIGHTS-The 75 Pseudomonas aeruginosa genomes from people with cystic fibrosis in the study collection included at least one Phage tail-like bacteriocins (PTLB) cluster. -From the 34 different PTLBs detected in the study collection, 7 were R-type, 10 were complex (R and F-type encoded) and 14 were F-type PTLBs. -11 new F-type PTLBs were described in the Pseudomonas aeruginosa collection under study. -An association between the O-antigen present on the surface of the Pseudomonas aeruginosa isolate and the encoded PTLB subtype was detected. -The R1 and F15 PTLBs subtypes display high antimicrobial activity both in vitro and in vivo (Galleria mellonella).

microbiology↗

bioRxiv2024

Involvement of Pf-like phages in resistance to phage infection in clinical isolates of P. aeruginosa from cystic fibrosis patients

Pseudomonas aeruginosa is a bacterial pathogen that is a major cause of lung infections in cystic fibrosis (CF) and other patients. Isolates of P. aeruginosa from CF patients commonly carry filamentous phages (Pf phages), a type of temperate phage known to be related to biofilm production and antibiotic sequestration. In this study, 12 new Pf-like phages were identified in a collection of clinical isolates of P. aeruginosa from CF patients. Analysis of the phage genomes revealed different anti-phage defence systems, described here for first time in these types of phages. Finally, relationships between resistance to phage infection and the presence of Pf-like phages and also between each defence system and resistance were observed. IMPORTANCEBacteria harbour a wide range of defence mechanisms to avoid phage infections. These mechanisms hamper the application of phage therapy because they can lead to the rapid acquisition of phage resistance. Temperate phages, including the filamentous phages, carry genes encoding virulence factors and also anti-phage defence mechanisms, as their survival depends on the host survival. In this study, we identified 12 new Pf-like phages encoding several different anti-phage defence mechanisms, some observed for the first time in this type of phage. A relationship between these phages and resistance to phage infection was also observed. The study findings are important as they provide information about newly discovered filamentous phages and their proteomes and also about the role of these phages in resistance to phage infections. Studying the genome of clinical isolates carrying these phages could help to improve phage therapy by targeting these phages or its genes.

microbiology↗

bioRxiv2024

Elucidating effects of single and multiple resistance mechanisms on bacterial response to meropenem by quantitative and systems pharmacology modeling and population genomics

Meropenem is commonly used against Pseudomonas aeruginosa. Traditionally, the time unbound antibiotic concentration exceeds the MIC (fT>MIC) is used to select carbapenem regimens. We aimed to: characterize the effects of different baseline resistance mechanisms on bacterial killing and resistance emergence; evaluate whether fT>MIC can predict these effects; and, develop a novel quantitative and systems pharmacology (QSP) model to describe effects of baseline resistance mechanisms on the time-course of bacterial response. Seven isogenic P. aeruginosa strains with a range of resistance mechanisms and MICs were used in 10-day hollow-fiber infection model studies. Meropenem pharmacokinetic profiles were simulated for various regimens (t1/2,meropenem=1.5h). All viable counts on drug-free, 3xMIC and 5xMIC meropenem-containing agar across all strains, five regimens and control (n=90 profiles) were simultaneously subjected to QSP modeling. Whole genome sequencing was completed for total population samples and emergent resistant colonies at 239h. Regimens achieving [≥]98%fT>1xMIC suppressed resistance emergence of the mexR knockout strain. Even 100%fT>5xMIC failed to achieve this against the strain with OprD loss and the ampD and mexR double-knockout strain. Baseline resistance mechanisms affected bacterial outcomes, even for strains with the same MIC. Genomic analysis revealed that pre-existing resistant subpopulations drove resistance emergence. During meropenem exposure, mutations in mexR were selected in strains with baseline oprD mutations, and vice versa, confirming these as major mechanisms of resistance emergence. Secondary mutations occurred in lysS or argS, coding for lysyl and arginyl tRNA synthetases, respectively. The QSP model well characterized all bacterial outcomes of the seven strains simultaneously, which fT>MIC could not.

microbiology↗

bioRxiv2021

Polyclonal pathogen populations accelerate the evolution of antibiotic resistance in patients

Antibiotic resistance poses a global health threat, but the within-host drivers of resistance remain poorly understood. Pathogen populations are often assumed to be clonal within hosts, and resistance is thought to emerge due to selection for de novo variants. Here we show that pulmonary populations of the opportunistic pathogen P. aeruginosa are often polyclonal. Crucially, resistance evolves rapidly in patients colonized by polyclonal populations through selection for pre-existing resistant strains. In contrast, resistance evolves sporadically in patients colonized by monoclonal populations due to selection for novel resistance mutations. However, strong trade-offs between resistance and fitness occur in polyclonal populations that can drive the loss of resistant strains. In summary, we show that the within-host diversity of pathogen populations plays a key role in shaping the emergence of resistance in response to treatment. One sentence summaryAntibiotic resistance evolves quickly in patients colonized by polyclonal pathogen populations.

evolutionary biology↗

bioRxiv2021

Whole genome sequencing evidences higher rates of relapse in Clostridioides difficile infection caused by PCR ribotype 106

Increasing prevalence and widespread of Clostridioides difficile infection (CDI) caused by the epidemic DH/NAP11/106/ST-42 has been observed worldwide, probably fostered by its great capacity to produce spores or the higher resistance rates found in some strains. Previous studies have also attributed higher recurrence rates to RT106 as compared to others. This study describes the genetic analysis by whole genome sequencing (WGS) of primary and recurrent isolates of RT106 to determine if the higher rate of recurrence associated to RT106 is due to relapses, caused by the same strain, or reinfections, caused by different strains. The whole-genome sequences of ten primaries and fourteen recurrent RT106 isolates from ten patients were obtained to determine MLST profiles, resistance mutations and phylogenetic relatedness between the different isolates by comparative single nucleotide variants (SNV) analysis using the C. difficile DH/NAP11/106/ST-42 genome as reference (GenBank accession: GCA_002234355.1). All isolates were classified as ST42 and SNVs comparative analysis showed that those belonging to the same patient were isogenic (differed by [≤]3 SNVs), with one exception (6 SNVs); while strains belonging to different patients were not (differing by 4 to 43 SNVs) with two exceptions of isogenic isolates from different patients, suggesting putative transmission events. Phylogenetic analysis suggested the presence of similar local epidemic lineages, except for one patient whose isolates clustered with different US isolates. All the isolates, except those clustering with the US lineage, were also associated to moxifloxacin resistant since all of them were resistant by agar diffusion (MIC >32) and contained the Thr82Ile mutation in gyrA. Our results evidence that recurrent Clostridioides difficile infections caused by RT06/ST42 are mainly due to relapses, caused by primary strains, showing the great capacity of RT106/ST42 to persist and cause recurrences as compared to other ribotypes.

microbiology↗

bioRxiv2020

Rapid evolution drives the rise and fall of carbapenem resistance during an acute Pseudomonas aeruginosa infection

It is well established that antibiotic treatment selects for resistance in pathogenic bacteria. However, the evolutionary responses of pathogen populations to antibiotic treatment during infections remain poorly resolved, especially in acute infections. Here we map the evolutionary responses to treatment in high definition through genomic and phenotypic characterization of >100 isolates from a patient with P. aeruginosa pneumonia. Antibiotic therapy (meropenem, colistin) caused a rapid crash of the P. aeruginosa population in the lung, but this decline was followed by the spread of meropenem resistance mutations that restrict antibiotic uptake (oprD) or modify LPS biosynthesis (wbpM). Low fitness strains with high-level meropenem resistance (oprD) were then replaced by high fitness strains with anti-resistance mutations in the MexAB-OprM efflux pump, causing a rapid decline in resistance to both meropenem and a collateral loss of resistance to a broad spectrum of antibiotics. In contrast, we did not observe any evolutionary responses to antibiotic treatment in the intestinal population of P. aeruginosa. Carbapenem antibiotics are key to the treatment of infections caused by Gram negative pathogens, and our work highlights the ability of natural selection to drive both the rapid rise and fall of carbapenem resistance during acute infections.

evolutionary biology↗