Percorrer por autor "Silva, Vanessa"
A mostrar 1 - 10 de 21
Resultados por página
Opções de ordenação
- Antimicrobial Resistance and Molecular Epidemiology of Staphylococcus aureus from Hunters and Hunting DogsPublication . Silva, Vanessa; Caniça, Manuela; Manageiro, Vera; Vieira-Pinto, Madalena; Pereira, José Eduardo; Maltez, Luís; Poeta, Patrícia; Igrejas, GilbertoSeveral studies have showed that a dog-to-human transmission of Staphylococcus aureus occurs. Hunting dogs do not have as much contact with their owners as dogs that live in the same household as the owners; however, these dogs have contact with their owners during hunting activities as well as when hunting game; therefore, we aimed to isolate S. aureus from hunters and their hunting dogs to investigate a possible S. aureus transmission. Nose and mouth samples were collected from 30 hunters and their 78 hunting dogs for staphylococcal isolation. The species identification was performed using MALDI-TOF. The antimicrobial susceptibility profiles were accessed using the Kirby-Bauer method and respective antimicrobial resistance genes were investigated by PCR. Multilocus sequence typing (MLST) and spa- and agr-typing was performed in all S. aureus isolates. S. aureus were detected in 10 (30%) human samples and in 11 (15.4%) dog samples of which 11 and 5 were methicillin-resistant S. aureus (MRSA). Other staphylococci were identified, particularly, S. pseudintermedius. Most S. aureus isolates were resistant to penicillin, erythromycin, and tetracycline. Evidence of a possible transmission of S. aureus between human and dogs was detected in three hunters and their dogs. S. aureus isolates were ascribed to 10 STs and 9 spa-types. A moderate colonization of S. aureus in hunting dogs and their owners was detected in this study. A few dog-to-dog and dog-to-human possible transmissions were identified.
- Bats as Hosts of Antimicrobial-Resistant Mammaliicoccus lentus and Staphylococcus epidermidis with Zoonotic RelevancePublication . Silva, Vanessa; Caniça, Manuela; de la Rivière, Rani; Barros, Paulo; Cabral, João Alexandre; Poeta, Patrícia; Igrejas, GilbertoBats are increasingly recognized as reservoirs for antimicrobial-resistant bacteria, playing a potential role in the dissemination of resistance genes across species and regions. In this study, 105 bats from 19 species in Portugal were sampled to investigate the presence, antimicrobial resistance, and genetic characteristics of Mammaliicoccus and Staphylococcus isolates. Thirteen Mammaliicoccus lentus and Staphylococcus epidermidis were recovered. Antimicrobial susceptibility testing revealed multidrug resistance in three isolates, with S. epidermidis carrying mph(C), msr(A), and dfrC genes, and M. lentus harboring salB, tet(K), and str. Notably, qacA was detected in S. epidermidis, highlighting its plasmid-associated potential for horizontal gene transfer to more pathogenic bacteria. Heavy metal resistance genes (arsB and cadD) were also identified, suggesting the role of environmental factors in co-selecting antimicrobial resistance. Molecular typing revealed the S. epidermidis strain as ST297, a clone associated with both healthy humans and invasive infections. These findings emphasize the need for monitoring bats as reservoirs of resistance determinants, particularly in the context of zoonotic and environmental health. The presence of mobile genetic elements and plasmids further underscores the potential for the dissemination of resistance. This study reinforces the importance of adopting a One Health approach to mitigate the risks associated with antimicrobial resistance.
- Comprehensive typing and genetic analysis of L. monocytogenes isolates: implication for food safety and antibiotic resistance surveillancePublication . Silva, Adriana; Silva, Vanessa; Borges, Vítor; Coelho, Anabela; Batista, Rita; Esteves, Alexandra; Igrejas, Gilberto; Saraiva, Cristina; Gomes, João Paulo; Poeta, PatríciaListeria species are commonly found in various environments and contaminated food, with livestock serving as a significant source of foodborne pathogens. Among these species, Listeria monocytogenes (L. monocytogenes) is particularly noteworthy as it can affect both livestock and humans. Antibiotics are frequently used in food animals for disease treatment and prevention on a large scale. This practice can lead to the selection of antibiotic-resistant bacterial strains, which can then spread to humans through the food chain. Consequently, L. monocytogenes, a ubiquitous foodborne pathogen, has been associated with global outbreaks of foodborne illnesses. To address this concern, the aim of the study was to conduct comprehensive typing and genetic analysis of 13 L. monocytogenes isolates obtained from food and food-processing environments.Among the 13 L. monocytogenes isolates, eight sequence types (ST) were identified: two isolates were identified as belonging to ST9; one as ST155; four as ST3, two as ST121, one as ST8; one as ST87; one as ST1; and one new ST belonging to CC121. Core-genome clustering analysis of L. monocytogenes was made to assess the genetic relatedness among the isolates. The core genome Multilocus Sequence Typing (cgMLST) analysis revealed three genetic clusters of high closely related isolates (≤7 allelic differences (ADs)): cluster 1. Regarding L. monocytogenes typing, ST3 was the most prevalent among the isolates, found in 4 isolates, followed by ST9 and ST121. Some of these isolates, like ST1, ST9 and ST87, were previously associated with human clinical cases. We used Whole Genome Sequencing (WGS) alongside epidemiological data to link strains to human illnesses and potential food sources. Through cgMLST analysis, we identified genetic clusters of closely related isolates, all linked to the same producers. This approach helped us pinpoint common sources of contamination and gain insights into the transmission dynamics of L. monocytogenes in the context of food safety and public health. The escalating antibiotic resistance in Listeria species, particularly in L. monocytogenes, emphasizes the need for heightened surveillance and improved hygiene practices in the food industry to curb the spread of antibiotic resistance and ensure food safety.
- Diversity and genetic lineages of environmental staphylococci: a surface water overviewPublication . Silva, Vanessa; Caniça, Manuela; Capelo, José L.; Igrejas, Gilberto; Poeta, PatríciaAntimicrobial resistance in the environmental dimension is one of the greatest challenges and emerging threats. The presence of resistant bacteria and resistance genes in the environment, especially in aquatic systems, has been a matter of growing concern in the past decade. Monitoring the presence of antimicrobial resistance species, in this particular case, Staphylococcus spp., in natural water environments could lead to a better understanding of the epidemiology of staphylococci infections. Thus, the investigation of natural waters as a potential reservoir and vehicle for transmission of these bacteria is imperative. Only a few studies have investigated the prevalence, antimicrobial resistance and genetic lineages of staphylococci in natural waters. Those studies reported a high diversity of staphylococci species and lineages in surface waters. Methicillin-resistant S. aureus were relatively prevalent in surface waters and, as expected, often presented a multidrug-resistant profile. There was a high diversity of S. aureus lineages in surface waters. The presence of S. aureus CC8 and CC5 suggests a human origin. Among the coagulase-negative staphylococci, the most frequently found in natural waters was S. warneri and S. epidermidis. These studies are extremely important to estimate the contribution of the aquatic environment in the spread of pathogenic bacteria.
- Diversity of methicillin-resistant staphylococci among wild Lepus granatensis: first detection of mecA-MRSA in haresPublication . Silva, Vanessa; Pereira, José Eduardo; Maltez, Luís; Ferreira, Eugénia; Manageiro, Vera; Caniça, Manuela; Capelo, José L.; Igrejas, Gilberto; Poeta, PatríciaMRSA in humans, pets and livestock have been widely investigated, nevertheless, there is still little information of MRSA in wild animals. Therefore, this study aimed to investigate the occurrence and antimicrobial resistance profiles of methicillin-resistant staphylococci (MRS) in wild Iberian hares and to characterize their genetic lineages. Samples from 83 wild hares (Lepus granatensis) were collected during the hunting season. Isolation of MRS was accomplish using Oxacillin Resistant Screening Agar medium with 2 mg/L of oxacillin. The susceptibility of the isolates was tested by the Kirby-Bauer disc diffusion method. The presence of resistance and virulence genes was studied by PCR. S. aureus strains were further characterized by multilocus sequence typing, agr, spa and SCCmec typing. From the 83 samples, 12 (14.45%) coagulase-negative staphylococci and 3 (3.6%) MRSA strains were isolated. Nine coagulase-negative isolates showed resistance to at least one antibiotic. One MRSA isolate showed a multidrug-resistant profile with resistances to ß-lactams, aminoglycosides, macrolides and lincosamides. All MRSA strains were ascribed to ST2855, t1190 and SCCmec type III. The frequency of MRSA strains in wild hares was low, nevertheless, the presence of MRSA in game animals is considered a public health problem and may represent a route of transmission between animals and humans.
- Emergence of community-acquired methicillin-resistant Staphylococcus aureus EMRSA-15 clone as the predominant cause of diabetic foot ulcer infections in PortugalPublication . Silva, Vanessa; Almeida, Francisco; Carvalho, José António; Castro, Ana Paula; Ferreira, Eugénia; Manageiro, Vera; Tejedor-Junco, María Teresa; Caniça, Manuela; Igrejas, Gilberto; Poeta, PatríciaMethicillin-resistant Staphylococcus aureus (MRSA) are often found in infected diabetic foot ulcers, in which the prevalence may reach 40%. These complications are one of the main causes of morbidity in diabetic patients. The objectives of this study were to investigate the prevalence and antimicrobial resistance of MRSA strains in infected diabetic foot ulcers and to characterize their genetic lineages. Samples collected from 42 type 2 diabetic patients, presenting infected foot ulcers, were seeded onto ORSAB plates with 2 mg/L of oxacillin for MRSA isolation. Susceptibility to 14 antimicrobial agents was tested by the Kirby-Bauer disk diffusion method. The presence of resistance genes, virulence factors, and the immune evasion cluster system was studied by PCR. All isolates were characterized by MLST, accessory gene regulator (agr), spa, and staphylococcal chromosomal cassette mec (SCCmec) typing. Twenty-five MRSA strains were isolated. All isolates showed resistance to penicillin and cefoxitin. Sixteen isolates showed phenotypic resistance to erythromycin being 7 co-resistant to clindamycin. Resistance to trimethoprim-sulfamethoxazole was found in 2 isolates harboring the dfrA and dfrG genes. The IEC genes were detected in 80% of isolates, 16 of which were ascribed to IEC-type B. Isolates were assigned to 12 different spa types. The MLST analysis grouped the isolates into 7 sequence types being the majority (68%) ascribed to SCCmec type IV. In this study, there was a high prevalence of the EMRSA-15 clone presenting multiple resistances in diabetic foot ulcers making these infections complicated to treat leading to a higher morbidity and mortality in diabetic patients.
- Escherichia coli as Commensal and Pathogenic Bacteria among Food-Producing Animals: Health Implications of Extended Spectrum β-Lactamase (ESBL) ProductionPublication . Ramos, Sónia; Silva, Vanessa; Dapkevicius, Maria de Lurdes Enes; Caniça, Manuela; Tejedor-Junco, María Teresa; Igrejas, Gilberto; Poeta, PatríciaEscherichia coli are facultative, anaerobic Gram-negative rods with many facets. Within resistant bacterial populations, they play an important ecological role and can be used as a bioindicator of antimicrobial resistance. All animal species used for food production, as well as humans, carry E. coli in their intestinal tracts; plus, the genetic flexibility and adaptability of this bacteria to constantly changing environments allows it to acquire a great number of antimicrobial resistance mechanisms. Thus, the prevalence of antimicrobial resistance in these commensal bacteria (or others, such as enterococci) can be a good indicator for the selective pressure caused by the use of antimicrobial agents, providing an early warning of the emergence of antimicrobial resistance in pathogens. As many as 90% of E. coli strains are commensals inhabiting the intestinal tracts of humans and warm-blooded animals. As a commensal, it lives in a mutually beneficial association with its hosts and rarely causes diseases. However, E. coli also remains as one of the most frequent causes of several common bacterial infections in humans and animals. In humans, it is the prominent cause of enteritis, community- and hospital-acquired urinary tract infection (UTI), septicemia, postsurgical peritonitis, and other clinical infections, such as neonatal meningitis, while, in farm animals, it is more prominently associated with diarrhea. On a global scale, E. coli can be considered the most important human pathogen, causing severe infection along with other major bacterial foodborne agents, such as Salmonella spp. and Campylobacter. Thus, the importance of resistance in E. coli, typically considered a benign commensal, should not be underestimated.
- First report of linezolid-resistant cfr-positive methicillin-resistant Staphylococcus aureus in humans in PortugalPublication . Silva, Vanessa; Almeida, Francisco; Silva, Adriana; Correia, Susana; Carvalho, José António; Castro, Ana Paula; Ferreira, Eugénia; Manageiro, Vera; Caniça, Manuela; Igrejas, Gilberto; Poeta, PatríciaLinezolid and vancomycin are the most reliable therapeutic agents to treat complicated soft tissue infections caused by multidrug-resistant methicillin-resistant Staphylococcus aureus (MRSA) strains. However, despite the fact that the prevalence of linezolid-resistant MRSA strains (LR-MRSA) remains overall low, in the past few years resistance to linezolid has been reported among human patients worldwide, imposing a public-health concern, in particular when associated with a mobile gene such as cfr [1]. The aim of this study was to identify LR-MRSA isolates recovered from infected diabetic foot ulcers and to characterise their antimicrobial resistance profiles and genetic lineage. (...)
- Genetic Complexity of CC5 Isolates Associated with Sternal Bursitis in Chickens: Antimicrobial Resistance, Virulence, Plasmids, and Biofilm Formation.Publication . Silva, Vanessa; Ribeiro, Jessica; Teixeira, Pedro; Pinto, Pedro; Vieira-Pinto, Madalena; Poeta, Patrícia; Caniça, Manuela; Igrejas, GilbertoSternal bursitis, a common inflammatory condition in poultry, poses significant challenges to both animal welfare and public health. This study aimed to investigate the prevalence, antimicrobial resistance, and genetic characteristics of isolates associated with sternal bursitis in chickens. Ninety-eight samples were collected from affected chickens, and 24 isolates were identified. Antimicrobial susceptibility testing revealed resistance to multiple agents, with a notable prevalence of aminoglycoside resistance genes. Whole genome sequencing elucidated the genetic diversity and virulence profiles of the isolates, highlighting the predominance of clonal complex 5 (CC5) strains. Additionally, biofilm formation assays demonstrated moderate biofilm production capacity among the isolates. These findings underscore the importance of vigilant monitoring and targeted interventions to mitigate the impact of sternal bursitis in poultry production systems.
- Genomic Analysis of Antibiotic Resistance and Virulence Profiles in Escherichia coli Linked to Sternal Bursitis in Chickens: A One Health PerspectivePublication . Ribeiro, Jessica; Silva, Vanessa; Freitas, Catarina; Pinto, Pedro; Vieira-Pinto, Madalena; Batista, Rita; Nunes, Alexandra; Gomes, João Paulo; Pereira, José Eduardo; Igrejas, Gilberto; Barros, Lillian; Heleno, Sandrina A.; Reis, Filipa S.; Poeta, PatríciaAbstract: Sternal bursitis is an underexplored lesion in poultry, often overlooked in microbiological diagnostics. In this study, we characterized 36 Escherichia coli isolates recovered from sternal bursitis in broiler chickens, combining phenotypic antimicrobial susceptibility testing, PCRbased screening, and whole genome sequencing (WGS). The genetic analysis revealed a diverse population spanning 15 sequence types, including ST155, ST201, and ST58. Resistance to tetracycline and ciprofloxacin was common, and several isolates carried genes encoding β-lactamases, including blaTEM-1B. Chromosomal mutations associated with quinolone and fosfomycin resistance (e.g., gyrA p.S83L, glpT_E448K) were also identified. WGS revealed a high number of virulence-associated genes per isolate (58–96), notably those linked to adhesion (fim, ecp clusters), secretion systems (T6SS), and iron acquisition (ent, fep, fes), suggesting strong pathogenic potential. Many isolates harbored virulence markers typical of ExPEC/APEC, such as iss, ompT, and traT, even in the absence of multidrug resistance. Our findings suggest that E. coli from sternal bursitis may act as reservoirs of resistance and virulence traits relevant to animal and public health. This highlights the need for including such lesions in genomic surveillance programs and reinforces the importance of integrated One Health approaches.
- «
- 1 (current)
- 2
- 3
- »