Biology subjects

Fonseca, E. L.

Publications and source records attributed to Fonseca, E. L..

3 recordsLinked to original sources

bioRxiv2024

Expression pattern of the ST heat-stable enterotoxin gene cassettes in Vibrios superintegrons

BACKGROUNDVibrio mimicus has been associated with a cholera-like diarrhea and other gastroenteritis due to the presence of virulence factors such as the heat-stable ST enterotoxin. In spite of its relevant role in Vibrio pathogenesis, there is still a lack of information concerning ST expression dynamics and associated genomic context. OBJECTIVEthis study aimed to determine the prevalence, genomic context, and expression of the st gene found in V. cholerae and V. mimicus strains. METHODSgenome sequencing, in silico analyses of st promoter region and genomic context, and relative quantification pf st expression by real time RT-PCR were applied. FINDINGSThe st gene was found within the SI of both Vibrio species, presenting variations in their amino acid sequences. The in silico analysis of the st 5UTR identified different promoter versions among them. Significant differences were observed in the st expression level, which varied from 10X to 640X-fold, correlating with the differences found in the promoter versions. MAIN CONCLUSIONSTherefore, the present study highlighted the link between the ST toxin gene and the superintegron, not only for V. cholerae, but also for V. mimicus. The differential st expression revealed that it is detrimental to the cognate promoter version, which would impact the toxin production and strain virulence.

genomics↗

bioRxiv2024

Genomic insights on the potential role of the accessory genome in the emergence of a novel geographically restricted K. pneumoniae lineage as a high-risk clone

Klebsiella pneumoniae causes life-threatening nosocomial infections and is featured by a remarkable propensity for multidrug resistance acquisition. Infections caused by multidrug- (MDR) and extensively drug-resistant (XDR) strains lead to a limitation of therapeutic options and an increase in persistent infections, and they are usually represented by high-risk lineages. Based on these features and their relevance to global public health, most of the studies focused on such high-risk clones, and little is known about the epidemiological and evolutionary dynamics of new/geographically restricted lineages. This study aimed to unveil the antimicrobial resistance and virulence genetic repertoire of a clinical XDR K. pneumoniae (Kp199) strain belonging to geographically-restricted ST, not linked to any known clonal complex. Its intrinsic (gyrA, parC, ramR, soxR and soxS mutations) and acquired resistome agreed with the observed XDR phenotype. An extensive arsenal of both antibiotic and heavy metal resistance genes was observed, as well as genes involved with resistance to several antiseptics currently used in clinical settings. The co-occurrence of blaKPC-2 and blaNDM-1 carbapenemase genes in Kp199 was an alarming finding since it could contribute to increased carbapenem resistance. Kp199 virulome was associated with bacterial survival and replication during infections. This study raises concern about a novel, geographically restricted K. pneumoniae lineage harbouring a huge resistome and virulome, which may strongly contribute to its successful establishment as an epidemic lineage. Therefore, our findings underscore the importance of vigilant surveillance and control measures to mitigate the threat posed by the potential emergence of new high-risk pandemic clones.

microbiology↗

bioRxiv2021

Emergence of XDR high-risk Pseudomonas aeruginosa ST309 in South America: a global comparative genomic analysis

Pseudomonas aeruginosa has been considered one of the major nosocomial pathogens associated with elevated morbidity and mortality worldwide. Outbreaks have been associated with few high-risk pandemic P. aeruginosa lineages, presenting a remarkable antimicrobial resistance. However, the biological features involved with the persistence and spread of such lineages among clinical settings remain to be unravel. This study reports the emergence of the ST309 P. aeruginosa lineage in South America/Brazil, more precisely, in the Amazon region. Global genomic analyses were performed with the Brazilian strain (PA834) and more 41 complete and draft ST309 genomes publicly available, giving insights about ST309 epidemiology and its resistome and mobilome. Antimicrobial susceptibility tests revealed that the Brazilian PA834 strain presented the XDR phenotype, which was mainly due to intrinsic resistance mechanisms. Genomic analyses revealed a heterogeneous distribution of acquired antimicrobial resistance genes among ST309 genomes, which included blaVIM-2, blaIMP-15 and qnrVC1, all of them associated with class 1 integrons. The mobilome mining showed the presence of Integrative and Conjugative Elements, transposons and genomic islands harbouring a huge arsenal of hevy metal resistance genes. Moreover, these elements also carried genes involved with virulence and adaptive traits. Therefore, the presence of such genes in ST309 lineage possibly accounted for the global spread and persistence of this emerging clone, and for its establishment as a pandemic lineage of clinical importance.

genomics↗