Percorrer por autor "Machado, Sandro"
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- BlaGES-6 producing Pseudomonas aeruginosa ST235 is involved in resistance to different β-lactamsPublication . de Sousa, Telma; Machado, Sandro; Carvalho, Márcia; Caniça, Manuela; Ramos, Miguel J.N.; Santos, Daniela; Beyrouthy, Racha; Bonnet, Richard; Hébraud, Michel; Gomes, João Paulo; Igrejas, Gilberto; Poeta, PatríciaMultidrug resistance in Pseudomonas aeruginosa, particularly resistance to carbapenem, represents a major challenge for public health. This study investigated resistance mechanisms in three P. aeruginosa isolates: HU63 (blaGES-6 carbapenemase-positive), HU141 (carbapenem-resistant without carbapenemase), and PAO1 (control). Genomic analysis revealed distinct sequence types (ST235 for HU63, ST253 for HU141) and chromosomal integration of resistance genes. HU63 harbored diverse resistance mechanisms, including β-lactamases (bla, bla, bla) and efflux pumps. Minimum inhibitory concentration assays demonstrated HU63's resistance to all β-lactams tested (meropenem, imipenem-cilastatin, ceftazidime, piperacillin-tazobactam), while HU141 remained susceptible except to cefoxitin and cloxacillin. Time-kill assays revealed tolerance phenotypes, with HU63 showing regrowth after 8-24 h despite initial reductions in bacterial density. Gene expression varied significantlydepending on the antibiotic and the isolate. The HU63 isolate (GES-6 positive) stands out for its marked induction of bla in all the antibiotics tested, contributing to its resistance to carbapenems and broad-spectrum cephalosporins. These expression profiles corroborate the classic molecular mechanisms of resistance: regulation of entry pores (oprD), activation of efflux pumps (mexA) and production of β-lactamases (bla, ampC) adapted to each situation. These findings underscore the multifactorial nature of resistance in Carbapenem-resistant Pseudomonas aeruginosa (CRPA), combining enzymatic inactivation, efflux, and genetic adaptability. The study emphasizes the urgent need for genomic surveillance to track high-risk clones and develop therapies targeting tolerance mechanisms alongside traditional resistance.
- Pseudomonas aeruginosa: One Health approach to deciphering hidden relationships in Northern PortugalPublication . de Sousa, Telma; Machado, Sandro; Caniça, Manuela; Ramos, Miguel J.N.; Santos, Daniela; Ribeiro, Miguel; Hébraud, Michel; Igrejas, Gilberto; Alves, Olimpia; Costa, Eliana; Silva, Augusto; Lopes, Ricardo; Poeta, PatríciaAims: Antimicrobial resistance in Pseudomonas aeruginosa represents a major global challenge in public and veterinary health, particularly from a One Health perspective. This study aimed to investigate antimicrobial resistance, the presence of virulence genes, and the genetic diversity of P. aeruginosa isolates from diverse sources. Methods and results: The study utilized antimicrobial susceptibility testing, genomic analysis for resistance and virulence genes, and multilocus sequence typing to characterize a total of 737 P. aeruginosa isolates that were collected from humans, domestic animals, and aquatic environments in Northern Portugal. Antimicrobial resistance profiles were analyzed, and genomic approaches were employed to detect resistance and virulence genes. The study found a high prevalence of multidrug-resistant isolates, including high-risk clones such as ST244 and ST446, particularly in hospital sources and wastewater treatment plants. Key genes associated with resistance and virulence, including efflux pumps (e.g. MexA and MexB) and secretion systems (T3SS and T6SS), were identified. Conclusions: This work highlights the intricate dynamics of multidrug-resistant P. aeruginosa across interconnected ecosystems in Northern Portugal. It underscores the importance of genomic studies in revealing the mechanisms of resistance and virulence, contributing to the broader understanding of resistance dynamics and informing future mitigation strategies.