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Nieto Ramirez, L. M.

Publications and source records attributed to Nieto Ramirez, L. M..

2 recordsLinked to original sources

A genome-wide atlas of antibiotic susceptibility targets and pathways to tolerance.

Detailed knowledge on how bacteria evade antibiotics and eventually develop resistance could open avenues for novel therapeutics and diagnostics. It is thereby key to develop a comprehensive genome-wide understanding of how bacteria process antibiotic stress, and how modulation of the involved processes affects their ability to overcome said stress. Here we undertake a comprehensive genetic analysis of how the major human pathogen Streptococcus pneumoniae responds to 20 antibiotics. We built a genome-wide atlas of drug susceptibility determinants and generate a genetic interaction network that connects cellular processes and genes of unknown function, which we show can be used as therapeutic targets. Pathway analysis reveals a genome-wide "tolerome", defined by cellular processes that can make a bacterium less susceptible, and often tolerant, in an antibiotic specific manner. Importantly, modulation of these processes confers fitness benefits during active infections under antibiotic selection. Moreover, screening of sequenced clinical isolates demonstrates that mutations in tolerome genes readily evolve and are frequently associated with resistant strains, indicating such mutations may be an important harbinger for the emergence of antibiotic resistance.

microbiology↗

Genetic profiling of Mycobacterium tuberculosis \"modern\" Beijing strains from Southwest Colombia

Beijing strains of Mycobacterium tuberculosis (lineage2) have been associated with drug-resistance and transmission of tuberculosis worldwide. Most of the Beijing strains identified in the Colombian pacific coast exhibited a multidrug resistant (MDR) phenotype, in contrast with the phenotype observed in Beijing isolates from other South-American countries. We wanted to evaluate the clonality and genetic background of the Beijing strains isolated in Colombia that belong mostly to the spoligo-international type (SIT) 190. Out of 37 Beijing stains characterized in an 8-years period, we identified five Beijing clones; 36 that belong to the SIT190 type and only one to SIT1. Two loci in VNTR typing: MIRU 39 and QUB11b exhibited the highest level of variation among these strains. Out of the 37 Beijing strains, only one was drug susceptible, 28 represented MDR-TB, four extensively drug resistant TB (XDR-TB) and four pre-XDR-TB. The mutations rpoB S531L and katG S315T1 were the most common among the MDR strains as reported elsewhere. Whole genome sequencing analysis allowed us to classify them as modern lineage Beijing strains, sharing up to 76 out of the 275 SNPs described in Beijing strains, as identified worldwide by Schurch et al; including 54 non-synonymous SNPs and 23 silent mutations. We were also able to confirm the presence of 8 specific SNPs that were so far only found in the Beijing strains from Colombia. The presence of modern Beijing strains, most of them representing MDR-TB, suggests a different origin of this M. tuberculosis lineage compared to other Beijing strains found in neighboring countries, such as Peru. The specific 8-SNP signature confirmed the identity of these Colombian Beijing MDR strains. This work may serve as a genetic baseline to study the evolution and spread of M. tuberculosis Beijing strains in Colombia, which play an important role in the control of MDR-TB.

microbiology↗