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Clinical Salmonella Typhimurium ST34 with metal tolerance genes and an IncHI2 plasmid carrying oqxAB-aac(6')-Ib-cr from Europe

Publication . Campos, Joana; Mourão, Joana; Marçal, Sara; Machado, Jorge; Novais, Carla; Peixe, Luísa; Antunes, Patrícia

Fluoroquinolones are critical antibiotics for treating severe Salmonella infections, and the widespread of resistant isolates included in diverse epidemiological scenarios and carrying plasmid-mediated quinolone resistance (PMQR) is a global threat. Among PMQR mechanisms, those encoded by oqxAB and aac(6′)-Ib-cr genes are of special concern as they also confer reduced susceptibility to other antibiotics (oqxAB: chloramphenicol, trimethoprim, olaquindox; aac(6′)-Ib-cr: aminoglycosides) and biocides [oqxAB: quaternary ammonium compounds (QACs)].2,3 Although oqxAB ± aac(6′)-Ib-cr are prevalent and widespread in Asia, where olaquindox is still widely used in animal production, they remain scarce in Europe. Here we describe the molecular characterization of clinical ciprofloxacin-resistant Salmonella enterica Typhimurium with concomitant presence of oqxAB and aac(6′)-Ib-cr recovered for the first time in Europe.

2016-03Journal article

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Tolerance to multiple metal stressors in emerging non-typhoidal MDR Salmonella serotypes: a relevant role for copper in anaerobic conditions

Publication . Mourão, Joana; Marçal, Sara; Ramos, Paula; Campos, Joana; Machado, Jorge; Peixe, Luísa; Novais, Carla; Antunes, Patrícia

Objectives: Factors driving the expansion of particular MDR Salmonella serotypes/clones are not completely understood. We assessed if emergent MDR Salmonella serotypes/clones were more enriched in metal tolerance genes (e.g. to Cu/Ag) than other less frequent ones, as an additional feature to survive in environments contaminated with metals. Methods: Metal (Cu pco/Ag,Cu sil/Hg mer/As ars/Te ter) tolerance genes screening (PCR/sequencing), MICs of CuSO4/AgNO3 (aerobiosis/anaerobiosis), genetic element characterization (S1/I-CeuI PFGE) and conjugation assays were performed in a well-characterized Salmonella collection (n = 275 isolates; 2000–14; 49 serotypes/clones). Results The sil ± pco genes were detected in 37% of isolates from diverse serotypes, mainly in emergent Rissen/ST469 and Typhimurium/ST34 European clone (100%), which are mostly associated with pig settings where Cu is highly used. These genes were frequently co-located with merA ± terF and/or antibiotic resistance genes in plasmids (100–270 kb; IncHI2/IncHI1/IncN/IncFIIA; mostly transferable by conjugation) or in the chromosome. Most sil ± pco+ isolates (77%) were MDR contrasting with sil ± pco− ones (48%). The sil ± pco+ isolates presented significantly higher MICCuSO4 under anaerobiosis (MIC50/MIC90 = 28/32 mM) and MICAgNO3 after previous Ag contact (MIC50/MIC90 > 3 mM) than sil− ones (MIC50/MIC90 = 2/8 mM to CuSO4; MIC50/MIC90 = 0.125/0.16 mM to AgNO3). Use of these modified methodological approaches allowed the establishment of CuSO4/AgNO3 tolerance cut-offs to differentiate sil+ and sil− isolates, here firstly proposed. Conclusions: This study demonstrates that acquisition of Cu/Ag tolerance genes (sil/pco genes) might contribute to the emergence of particular clinically relevant MDR Salmonella serotypes/clones by facilitating their survival in diverse metal-contaminated settings, particularly in pig production. Assessment of control measures for the use and/or accumulation of metals in diverse environments are needed to prevent a wider expansion of such strains or the emergence of new ones.

2016-08Journal article

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Genetic Diversity and Antibiotic Resistance Among Coagulase-Negative Staphylococci Recovered from Birds of Prey in Portugal

Publication . Sousa, Margarida; Silva, Nuno; Igrejas, Gilberto; Sargo, Roberto; Benito, Daniel; Gómez, Paula; Lozano, Carmen; Manageiro, Vera; Torres, Carmen; Caniça, Manuela; Poeta, Patrícia

Wild animal populations in contact with antimicrobials and antimicrobial resistant bacteria that are daily released into the environment are able to become unintentional hosts of these resistant microorganisms. To clarify this issue, our study evaluated the presence of antibiotic resistance determinants on coagulase-negative staphylococci recovered from birds of prey and studied their genetic relatedness by pulsed-field gel electrophoresis (PFGE). The unusual vga(A) and erm(T) genes, which confer resistance to clindamycin and erythromycin, respectively, were detected in Staphylococcus sciuri or Staphylococcus xylosus strains and the tet(K) gene in Staphylococcus kloosii. The PFGE patterns showed that three S. xylosus (isolated of Strix aluco and Otus scops) and two S. sciuri (recovered from Strix aluco and Milvus migrans) were clonally indistinguishable. These animals could be a source of unusual antimicrobial resistance determinants for highly used antibiotics in veterinary clinical practice.

2016-12Journal article

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First report on MRSA CC398 recovered from wild boars in the north of Portugal. Are we facing a problem?

Publication . Sousa, Margarida; Silva, Nuno; Manageiro, Vera; Ramos, Sónia; Coelho, António; Gonçalves, David; Caniça, Manuela; Torres, Carmen; Igrejas, Gilberto; Poeta, Patrícia

The aim of the present study was to evaluate the resistance of Staphylococcus aureus recovered from wild boars, to analyze their genetic lineages, and to investigate the susceptibility to oxacillin. Samples from mouth and nose of 45 wild boars (Sus scrofa) were collected during hunt activity from November 2012 to January 2013 in the North of Portugal. S. aureus isolates were recovered from 30 of these samples (33%); one isolate/sample was further studied. The susceptibility of the isolates was tested by disk-diffusion test against 14 antimicrobial agents and minimal inhibitory concentration was used to test oxacillin according to EUCAST guidelines. The genetic lineages of S. aureus were characterized by agr-typing, spa-typing and MLST. From the 30 isolates, 18 S. aureus were susceptible to all antibiotics tested and 7 presented resistance to one or more of the following antibiotics: penicillin (n=3), oxacillin (n=4), cefoxitin (n=1), clindamycin (n=2), gentamicin (n=1), fusidic acid (n=1), ciprofloxacin (n=2), tetracycline (n=1) and linezolid (n=1). One MRSA CC398 (spa-type t899) isolate was detected (oxacillin MIC=32mg/L and mecA-positive), which presented resistance to penicillin, tetracycline, and ciprofloxacin and contained the genes of immune evasion cluster (IEC) system (type B). The 29 methicillin-susceptible isolates were typed as ST1 (t1533), ST133 (t3583), ST1643 (t10712), ST2328 (t3750) and the new STs (3220, 3222, 3223, 3224) associated to new spa-types t14311 and t14312. The agr-types I, II, III and IV were identified. It is a matter of concern when MRSA and some specific lineages of S. aureus are taken as commensal habitants of the skin and nose of wild animals and are characterized with resistance to various antimicrobial agents in clinical use.

2017-10-15Journal article

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Drug Repurposing for Schistosomiasis: Combinations of Drugs or Biomolecules

Publication . Gouveia, Maria; Brindley, Paul; Gärtner, Fátima; Costa, José; Vale, Nuno

Schistosomiasis is a major neglected tropical disease. Control of schistosomiasis currently relies on a single drug, praziquantel, and despite its efficacy against the all schistosome species that parasitize humans, it displays some problematic drawbacks and alone is ineffective in counteracting adverse pathologies associated with infection. Moreover, due to the development of the potential emergence of PZQ-resistant strains, the search for additional or alternative antischistosomal drugs have become a public health priority. The current drug discovery for schistosomiasis has been slow and uninspiring. By contrast, repurposing of existing approved drugs may offer a safe, rapid and cost-effective alternative. Combined treatment with PZQ and other drugs with different mode of action, i.e., antimalarials, shows promise results. In addition, a combination of anthelminthic drugs with antioxidant might be advantageous for modulating oxidative processes associated with schistosomiasis. Herein, we review studies dealing with combination therapies that involve PZQ and other anthelminthic drugs and/or antioxidant agents in treatment of schistosomiasis. Whereas PZQ combined with antioxidant agents might or might not interfere with anthelminthic efficacy, combinations may nonetheless ameliorate tissue damage and infection-associated complications. In fact, alone or combine with other drugs, antioxidants might be a valuable adjuvant to reduce morbidity and mortality of schistosomiasis. Therefore, attempting new combinations of anthelmintic drugs with other biomolecules such as antioxidants provides new avenues for discovery of alternatives to PZQ.

2018-02-05Journal article

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