Percorrer por autor "Quinteira, Sandra"
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- Dairy cattle and the iconic autochthonous cattle in northern Portugal are reservoirs of multidrug-resistant Escherichia coliPublication . Quinteira, Sandra; Dantas, Rui; Pinho, Luís; Campos, Carla; Freitas, Ana R.; Brito, Nuno V.; Miranda, Carla; Campos, CarlaAnimals destined for human consumption play a key role in potentially transmitting bacteria carrying antibiotic resistance genes. However, there is limited knowledge about the carriage of antibiotic-resistant bacteria in native breeds. We aimed to characterize the phenotypic profiles and antibiotic resistance genes in Escherichia coli isolated from bovines, including three native Portuguese bovine breeds. Forty-nine E. coli isolates were selected from 640 fecal samples pooled by age group (eight adult or eight calf samples) from each farm, representing both dairy cattle raised in intensive systems and meat cattle raised in extensive systems in Northern Portugal. The presumptive E. coli colonies plated onto MacConkey agar were confirmed using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). The antibiotic resistance profiles were screened by antimicrobial susceptibility testing (EUCAST/CLSI guidelines), and the antibiotic resistance genes by PCR. Most isolates showed resistance to ampicillin (69%), tetracycline (57%), gentamicin (55%), and trimethoprim + sulfamethoxazole (53%), with no resistance to imipenem. Resistance to at least one antibiotic was found in 92% of isolates, while 59% exhibited multidrug resistance. Most calf isolates, including those from native breeds, showed a multidrug-resistant phenotype. Among the adults, this was only observed in Holstein-Friesian and Barrosã cattle. None of the Holstein-Friesian isolates were susceptible to all the tested antibiotics. ESBL-producing E. coli was identified in 39% of isolates, including those from Holstein-Friesian calves and adults, Cachena calves and Minhota adults. The sul2 gene was detected in 69% of isolates, followed by blaCTX-M (45%), aac(3′)-IV (41%), and aac(6′)-Ib-cr (31%), with a higher prevalence in adults. This pioneering study highlights the concerning presence of multidrug-resistant E. coli in native Portuguese cattle breeds.
- Diagnostic pitfalls in Staphylococcus spp. surveillance: lessons from a multinational university student cohortPublication . Pinheiro, Bárbara; Gomes-Sampaio, Luís M.; Pacheco, Patrícia; Campos, Carla; Braz, Maria Pranto; Coelho, Cristina; Miranda, Carla; Quinteira, Sandra; Freitas, Ana R.; Campos, CarlaStaphylococcus aureus is a leading cause of severe and hard-to-treat human infections, particularly when resistant to cefoxitin due to the presence of the mecA gene [1]. However, diagnostic challenges arise from the misidentification of S. aureus and related species when relying on classical identification methods (mannitol fermentation;coagulase production), as well as from the detection of strains carrying the mecA gene but phenotypically susceptible to cefoxitin -known as "stealth" strains [2]. Building upon a previous collection of S. aureus from healthy students’ nares [3], we aimed to expand this collection with new samples, assess the occurrence of “stealth” isolates, and further investigate cases of incongruent identification. Nasal swab samples (n=557) from 507 students (median-23-years; 9 countries) attending alarge university (Porto district) were collected between March 2022 and November 2024. They were inoculated on to mannitol-salt agar and, in parallel, enriched in brain-heart-broth with 6.5%NaCl further plated on to ChromID® MRSA-SMART. Isolates deriving from mannitol-salt (only fermenting colonies) and chromogenic (all typical colonies) agar media were stored for species identification (MALDI-TOFMS), cefoxitin-susceptibility (disk-diffusion), and mecA gene screening (PCR). Staphylococcus aureus was identified in 46% (256/557; 6 countries) of cases. Other Staphylococcus species included S. haemolyticus(n=5), S. capitis(n=3), S. warneri(n=3), S. saprophyticus(n=1), S. simulans(n=1), and S. ureilyticus(n=1). These isolates expressed variable coagulase production (7 positive, 7 negative).On another hand, a non-fermenting S. aureus was detected (cromogenic medium).Ten (1.8%) students were colonized with methicillin-resistant staphylococci species carrying mecA including S. aureus (n=6), S. haemolyticus (n=3), S.ureilyticus (n=1). The mecA gene was also detected in 4/16 (25%; 3 Portuguese, 1 Italian) S. aureus susceptible to cefoxitin, the so-called “stealth”strains. Screening is ongoing in more isolates. Our study highlights the importance of integrating both phenotypic and genotypic methods for Staphylococcus accurate identification. Furthermore, the detection of stealth strains in healthy students underscores the need for robust community-based screening, as S. aureus carriage may be underestimated. Future studies will unveil whether these strains are capable of reversion to resistência.
- Identification of linezolid-resistant Enterococcus spp. in calves: findings from Portuguese high-yielding dairy farmsPublication . Ribeiro, Alícia; Teixeira, Maria J.; Pinho, Luís; Campos, Carla; Novais, Carla; Peixe, Luísa; Brito, Nuno V.; Quinteira, Sandra; Miranda, Carla; Freitas, Ana R.; Campos, CarlaAntimicrobial resistance (AMR) is a global health threat requiring a One Health approach, asantibiotic-resistant bacteria canspread between animals and humans. Enterococcusspp., particularly E. faecium(Efm) and E. faecalis(Efs),are keyAMR indicators due to their role as gut commensals and their potential as reservoirs of resistance genes.They are also opportunistic pathogensthat can cause severe human infections. Cattle are a recognized reservoir of multidrug-resistant (MDR) Enterococcusspp.,yet remain among the least studied food-producing animals in this context[1,2]. To assess if contemporary faecal samples from main cattle farms in Northern Portugal carry clinically relevant antibiotic-resistant Enterococcusspp. Thirty bovine fecal swab samples were collected from 10 high-yielding farms with Holstein-Friesian dairy cattle in 2 cities during 2023[3]. Sample processing included pre-enrichment (37ºC/18h) without/with antibiotics (ampicillin 16μg/mL, vancomycin 8μg/mL or florfenicol 16μg/mL) followed by plating onto Slanetz–Bartley selective agar, without/with the same antibiotics (37°C/48h). Typical colonies weres aved for identification (MALDI-TOF MS) and antibiotic susceptibility test (disk diffusion;EUCAST/CLSI). Prevalence percentages were calculated on a per-sample basis.All samples contained Enterococcus(n=43) that were identified as Efm(n=18,60%), E. hirae(n=14, 47%), Efs(n=9, 30%), E. casseliflavus and E. durans(n=1 each, 3%); and resistant to erythromycin (44%), tetracycline (39%), chloramphenicol (20%), ampicillin, linezolid, high-level streptomycin (17%each), ciprofloxacin(13%), and high-level gentamicin (7%). MDR isolates (23%) were mostly obtained from calves rather than adults, and only found in Efs(67%) and Efm(50%) species. Linezolid-resistant isolates were only recovered from supplemented media with florfenicol while those resistant to ampicillin were better detected using culture medium with ampicillinor florfenicol. Ampicillin resistance was only detected in Efm while linezolid resistance was identified in both Efmand Efs (all calves, all MDR, 2 farms). Our study shows that dairy cattle carry MDR Enterococcus spp.,including strains resistant to critically important antibiotics in the treatment of human infections (linezolid). These findings underscore the urgent need for sustained AMR surveillance and cross-sector collaboration within a One Health framework.