Letteratura scientifica selezionata sul tema "Cc3618"

Fifteen percent of all methicillin-resistantStaphylococcus aureus(MRSA) clonal complex 398 (CC398) human carriers detected in The Netherlands had not been in direct contact with pigs or veal calves. To ensure low MRSA prevalence, it is important to investigate the likely origin of this MRSA of unknown origin (MUO). Recently, it was shown that CC398 strains originating from humans and animals differ in the presence of specific mobile genetic elements (MGEs). We hypothesized that determining these specific MGEs in MUO isolates and comparing them with a set of CC398 isolates of various known origin might provide clues to their origin. MUO CC398 isolates were compared to MRSA CC398 isolates obtained from humans with known risk factors, a MRSA CC398 outbreak isolate, livestock associated (LA) MRSA CC398 isolates from pigs, horses, chickens, and veal calves, and five methicillin-susceptibleStaphylococcus aureus(MSSA) CC398 isolates of known human origin. All strains werespatyped, and the presence or absence of,scn,chp, φ3int, φ6int, φ7int,rep7,rep27, andcadDXwas determined by PCRs. The MRSA CC398 in humans, MUO, or MRSA of known origin (MKO) resembled MRSA CC398 as found in pigs and not MSSA CC398 as found in humans. The distinct human MSSA CC398spatype, t571, was not present among our MRSA CC398 strains; MRSA CC398 was tetracycline resistant and carried no φ3 bacteriophage withscnandchp. We showed by simple PCR means that human MUO CC398 carriers carried MRSA from livestock origin, suggestive of indirect transmission. Although the exact transmission route remains unknown, direct human-to-human transmission remains a possibility as well.

Staphylococcus aureus (SA) belonging to the clonal complex 398 (CC398) took a special place within the species due to its spread throughout the world. SA CC398 is broadly separated in two subpopulations: livestock-associated methicillin-resistant SA (MRSA) and human-associated methicillin-susceptible SA (MSSA). Here, we reviewed the global epidemiology of SA CC398 in human clinical infections and focused on MSSA CC398. The last common ancestor of SA CC398 was probably a human-adapted prophage φSa3-positive MSSA CC398 strain, but the multiple transmissions between human and animal made its evolution complex. MSSA and MRSA CC398 had different geographical evolutions. Although MSSA was present in several countries all over the world, it was mainly reported in China and in France with a prevalence about 20%. MSSA CC398 was frequently implicated in severe infections such as bloodstream infections, endocarditis, and bone joint infections whereas MRSA CC398 was mainly reported in skin and soft tissue. The spread of the MSSA CC398 clone is worldwide but with a heterogeneous prevalence. The prophage φSa3 played a crucial role in the adaptation to the human niche and in the virulence of MSSA CC398. However, the biological features that allowed the recent spread of this lineage are still far from being fully understood.

Abstract Background Tetracycline resistance (TetR) is a marker of livestock-associated MRSA of lineage CC398. Objectives To determine the MRSA CC398 prevalence among TetR-MRSA recovered in Spanish hospitals located in regions with different pig-farming densities, and the influence of pig density as a key risk factor for its acquisition. Methods TetR-MRSA isolates (n = 232) recovered from clinical and epidemiological samples during January–June 2016 in 20 hospitals in 13 regions with different pig-farming densities were analysed. MRSA CC398 identification, detection of spa types, methicillin resistance genes and immune evasion cluster (IEC) genes were performed by PCR/sequencing. Statistical analyses were performed to establish the relationships between MRSA CC398 prevalence and pig density. Results The global MRSA prevalence was 29.7% (6.9% TetR-MRSA/MRSA), with 137 CC398 isolates recovered, representing 4.1% of total MRSA and 59.1% of TetR-MRSA. Among MRSA CC398, 16 different spa types were recorded (t011: 72.3%), and all but two strains were IEC negative. Higher pig-density regions were associated with significant MRSA CC398 increases in hospitals located in adjacent regions (P < 0.001). Linear regression models explained the relationships between MRSA CC398 and pig density (P < 0.001), with an increase of 6.6 MRSA CC398 cases per 100 MRSA per increase of 100 pigs/km2 in a region. Conclusions High pig density leads to a significant increase in MRSA CC398 in hospitals in Spain, and its combination with a high human population could help its dissemination. In Spain, the prevalence of the zoonotic CC398 lineage is closely related to pig-farming density; therefore, specific tools could be implemented in order to detect its dissemination.

ABSTRACT Small noncoding regulatory RNAs (sRNAs) play a key role in the posttranscriptional regulation of many bacterial genes. The genome of Caulobacter crescentus encodes at least 31 sRNAs, and 27 of these sRNAs are of unknown function. An overexpression screen for sRNA-induced growth inhibition along with sequence conservation in a related Caulobacter species led to the identification of a novel sRNA, CrfA, that is specifically induced upon carbon starvation. Twenty-seven genes were found to be strongly activated by CrfA accumulation. One-third of these target genes encode putative TonB-dependent receptors, suggesting CrfA plays a role in the surface modification of C. crescentus, facilitating the uptake of nutrients during periods of carbon starvation. The mechanism of CrfA-mediated gene activation was investigated for one of the genes predicted to encode a TonB-dependent receptor, CC3461. CrfA functions to stabilize the CC3461 transcript. Complementarity between a region of CrfA and the terminal region of the CC3461 5′-untranslated region (5′-UTR) and also the behavior of a deletion of this region and a site-specific base substitution and a 3-base deletion in the CrfA complementary sequence suggest that CrfA binds to a stem-loop structure upstream of the CC3461 Shine-Dalgarno sequence and stabilizes the transcript.

ABSTRACTStaphylococcus aureusclonal complex 398 (CC398) is associated with disease in humans and livestock, and its origins and transmission have generated considerable interest. We performed a time-scaled phylogenetic analysis of CC398, including sequenced isolates from the United Kingdom (Scotland), along with publicly available genomes. Using state-of-the-art methods for mapping traits onto phylogenies, we quantified transitions between host species to identify sink and source populations for CC398 and employed a novel approach to investigate the gain and loss of antibiotic resistance in CC398 over time. We identified distinct human- and livestock-associated CC398 clades and observed multiple transmissions of CC398 from livestock to humans and between countries, lending quantitative support to previous reports. Of note, we identified a subclade within the livestock-associated clade comprised of isolates from hospital environments and newborn babies, suggesting that livestock-associated CC398 is capable of onward transmission in hospitals. In addition, our analysis revealed significant differences in the dynamics of resistance to methicillin and tetracycline related to contrasting historical patterns of antibiotic usage between the livestock industry and human medicine. We also identified significant differences in patterns of gain and loss of different tetracycline resistance determinants, which we ascribe to epistatic interactions between the resistance genes and/or differences in the modes of inheritance of the resistance determinants.

In 2019, the biggest listeriosis outbreak by Listeria monocytogenes (Lm) in the South of Spain was reported, resulting in the death of three patients from 207 confirmed cases. One strain, belonging to clonal complex 388 (Lm CC388), has been isolated. We aimed to determine the Lm CC388 virulence in comparison with other highly virulent clones such as Lm CC1 and Lm CC4, in vitro and in vivo. Four L. monocytogenes strains (Lm CC388, Lm CC1, Lm CC4 and ATCC 19115) were used. Attachment to human lung epithelial cells (A549 cells) by these strains was characterized by adherence and invasion assays. Their cytotoxicities to A549 cells were evaluated by determining the cells viability. Their hemolysis activity was determined also. A murine intravenous infection model using these was performed to determine the concentration of bacteria in tissues and blood. Lm CC388 interaction with A549 cells is non-significantly higher than that of ATCC 19115 and Lm CC1, and lower than that of Lm CC4. Lm CC388 cytotoxicity is higher than that of ATCC 19115 and Lm CC1, and lower than that of Lm CC4. Moreover, Lm CC388 hemolysis activity is lower than that of the Lm CC4 strain, and higher than that of Lm CC1. Finally, in the murine intravenous infection model by Lm CC388, higher bacterial loads in tissues and at similar levels of Lm CC4 were observed. Although a lower rate of mortality of patients during the listeriosis outbreak in Spain in 2019 has been reported, the Lm CC388 strain has shown a greater or similar pathogenicity level in vitro and in an animal model, like Lm CC1 and Lm CC4.

ABSTRACTThe tetracycline resistance genetet(K) was shown to be integrated within the predominant staphylococcal cassette chromosomemec(SCCmec) element of Danish livestock-associated methicillin-resistantStaphylococcus aureusCC398 (LA-MRSA CC398). These LA-MRSA CC398 isolates already possessedtet(M), but the acquisition oftet(K) significantly improved their fitness at sublethal concentrations of tetracycline. Becausetet(K) is genetically linked to SCCmec, the use of tetracycline in food animals may have contributed to the successful spread of LA-MRSA CC398.

Among clinically relevant lineages of Staphylococcus aureus, the lineage or clonal complex 398 (CC398) is of particular interest. Strains from this lineage were only described as livestock colonizers until 2007. Progressively, cases of infection were reported in humans in contact with farm animals, and now, CC398 isolates are increasingly identified as the cause of severe infections even in patients without any contact with animals. These observations suggest that CC398 isolates have spread not only in the community but also in the hospital setting. In addition, several recent studies have reported that CC398 strains are evolving towards increased virulence and antibiotic resistance. Identification of the origin and emergence of this clonal complex could probably benefit future large-scale studies that aim to detect sources of contamination and infection. Current evidence indicates that the evolution of CC398 strains towards these phenotypes has been driven by the acquisition of prophages and other mobile genetic elements. In this short review, we summarize the main knowledge of this major lineage of S. aureus that has become predominant in the human clinic worldwide within a single decade.

In this conceptual review, we thoroughly searched for appropriate English articles on nasal staphylococci carriage among healthy people with no reported risk of colonization (Group A), food handlers (Group B), veterinarians (Group C), and livestock farmers (Group D) published between 2000 and 2021. Random-effects analyses of proportions were performed to determine the pooled prevalence of S. aureus, MRSA, MRSA-CC398, and MSSA-CC398, as well as the prevalence of PVL-positive S. aureus from all eligible studies. A total of 166 eligible papers were evaluated for Groups A/B/C/D (n = 58/31/26/51). The pooled prevalence of S. aureus and MRSA in healthy humans of Groups A to D were 15.9, 7.8, 34.9, and 27.1%, and 0.8, 0.9, 8.6, and 13.5%, respectively. The pooled prevalence of MRSA-CC398 nasal carriage among healthy humans was as follows: Group A/B (<0.05%), Group C (1.4%), Group D (5.4%); and the following among Group D: pig farmers (8.4%) and dairy farmers (4.7%). The pooled prevalence of CC398 lineage among the MSSA and MRSA isolates from studies of the four groups were Group A (2.9 and 6.9%), B (1.5 and 0.0%), C (47.6% in MRSA), and D (11.5 and 58.8%). Moreover, MSSA-CC398 isolates of Groups A and B were mostly of spa-t571 (animal-independent clade), while those of Groups C and D were spa-t011 and t034. The MRSA-CC398 was predominately of t011 and t034 in all the groups (with few other spa-types, livestock-associated clades). The pooled prevalence of MSSA and MRSA isolates carrying the PVL encoding genes were 11.5 and 9.6% (ranges: 0.0–76.9 and 0.0–28.6%), respectively. Moreover, one PVL-positive MSSA-t011-CC398 isolate was detected in Group A. Contact with livestock and veterinary practice seems to increase the risk of carrying MRSA-CC398, but not in food handlers. Thus, this emphasizes the need for integrated molecular epidemiology of zoonotic staphylococci.

ABSTRACTThe structures of staphylococcal cassette chromosomemec(SCCmec) elements carried by 31 clonal complex 398 (CC398) methicillin-resistantStaphylococcus aureus(MRSA) strains isolated from the participants at a conference were analyzed. The SCCmecs were classified into novel types, namely, IX, X, V(5C2&5) subtype c, and IVa. Type V(5C2&5) subtype c, IX, and X SCCmecs carried genes conferring resistance to metals. The structures of SCCmecs from CC398 strains were distinct from those normally found in humans, adding to the evidence that humans are not the original host for CC398.

El Staphylococcus aureus resistente a la meticilina (SARM) es un importante patógeno humano que causa infecciones nosocomial y adquirida en la comunidad en todo el mundo. Desde 2003, el SARM asociado a la ganadería (SARM-AG) se ha identificado tanto en animales como en seres humanos en zonas con ganadería en Europa, América del Norte y Asia. Asimismo dentro del grupo de SARM-AG están incluidas los clones CC398 y CCT9 entre otros. Estudios previos establecieron que la resistencia a la tetraciclina (tetR) podría ser un buen marcador para la determinación rápida de las cepas CC398 y CC relacionadas con otros animales entre los aislados clínicos de SARM. La exposición del ser humano a la ganadería constituye un factor de riesgo para la colonización por SARM CC398 y también para el desarrollo de una posible infección. La mayoría de infecciones producidas por SARM CC398 están relacionadas con infecciones de la piel y tejidos blandos. Sin embargo, se han reportado en Europa, Asia, y Estados Unidos infecciones graves. La comarca de Osona (Barcelona) es una comarca con una antigua tradición en la industria del cerdo y por consiguiente es una de las comarcas con mayor densidad de cerdos. Para conocer la importancia de SARM CC398 en un área con alta densidad de granjas de cerdos como es la comarca de Osona se han realizado tres estudios en diferentes poblaciones. El primero fue en granjas de cerdos, en donde se observó una alta prevalencia de SARM CC398 en granjeros (58%) y en cerdos (46%). Se observó que los granjeros de cerdos que trabajan en granjas con más de 1.250 cerdos tienen más probabilidades de ser positivos para SARM CC398. Asimismo se describe por primera vez la prevalencia de SARM CC398 en Cataluña, la región de España con mayor densidad de cerdos. El segundo trabajo se analizaron 4 años (2012-2015), en donde se observó que la prevalencia de SARM-TetRR (especialmente del linaje CC398) en la comarca de Osona (Barcelona), en pacientes hospitalizados o relacionados con la asistencia sanitaria es elevada, representando más del 50% del total de SARM aislados. El aumento de detección de SARM-TetR y especialmente CC398 durante los últimos años hace pensar que en un futuro podría ser el clon SARM comunitario en nuestra zona. Por otra parte se describen las características clínicas de los pacientes en los que se han identificado SARM-TetRR siendo más jóvenes, con menos comorbilidad, menos ingresos hospitalarios, con una adquisición extrahospitalaria y en un 50% con contacto con granjas de cerdos. Se han detectado infecciones graves por SARM ST398 y con una mortalidad similar a la de SARM-TetSS. En el tercer trabajo se analizaron seis residencias de ancianos y se observó que la prevalencia de colonización por SARM ST398 en residencias de ancianos en la Comarca de Osona ( Barcelona, España) representa el 15,6% del total de SARM. Las residencias son un reservorio conocido de SARM y en la zona estudiada también podrían ser de SARM ST398. Con estos tres trabajos se demuestra que el SARM CC398 es un linaje prevalente en la comarca de Osona y con una implicación clínica significativa. En este sentido las futuras investigaciones apuntan a conocer en otras poblaciones de riesgo como son los trabajadores de un matadero de cerdos y la población general en la comarca de Osona, la prevalencia y las implicaciones clínicas del SARM CC398.
Methicillin-resistant Staphylococcus aureus (MRSA) is a major human pathogen which causes nosocomial and community-acquired infections all over the world. Since 2003 livestock-associated MRSA (LA-MRSA) has been identified in animals as well as in humans in areas of Europe, North America and Asia with livestock populations. Furthermore, the LA-MRSA group includes, amongst others, clones CC398 and CCT9. Previous studies have established that tetracycline resistance (tetR) could be a good marker for rapid determination of CC398 strains and CC strains related to other animals from amongst MRSA clinical isolates. Human exposure to livestock constitutes a risk factor for colonization with MRSA CC398 as well as for development of possible infections. The majority of infections caused by MRSA CC398 are linked to skin and soft tissue infections. Nonetheless, serious infections have been reported in Europe, Asia and the United States. The region of Osona (Barcelona) is an area which has traditionally had a large pig-breeding industry and consequently it is one of the areas with the highest pig-population densities. In order to evaluate the significance of MRSA CC398 in an area with a high density of pig farms, such as the region of Osona, three studies were carried out in different segments of the population. The first looked at pig farms, where a high prevalence of MRSA CC398 was observed in farmers (58%) and pigs (46%). Pig farmers who work on farms with more than 1,250 pigs were found to have a higher probability of being MRSA CC398 positive. Furthermore, the prevalence of MRSA CC398 in Catalonia, the region in Spain with the highest pig density, is described for the first time. The second study analyzed 4 years (2012-2015) during which the prevalence of MRSA- TetRR (especially that belonging to the clonal lineage CC398) in the area of Osona (Barcelona) was observed to be high in hospital patients and patients in contact with the health care services, accounting for more than 50% of the total of MRSA isolates. The increase in detection of MRSA-TetR and especially of CC398 in recent years suggests that it might become the MRSA community-associated clone in our area in the future. Additionally, the clinical characteristics of the patients identified as being MRSA-TetRR showed younger patients, with fewer comorbidities, fewer hospital stays, with community-acquired infections and, in 50% of cases, contact with pig farms. Serious MRSA ST398 infections with a mortality rate similar to that of MRSA-TetSS were detected. In the third study six nursing homes were analyzed and the prevalence of MRSA ST398 colonization in nursing homes in the Osona area (Barcelona, Spain) was found to account for 15.60% of the total of MRSA. Nursing homes are a well-known reservoir of MRSA and maybe also of MRSA ST398 in the area included in the study. MRSA CC398 is shown by these three studies to be a prevalent lineage in the area of Osona, with significant clinical implications. Consequently future investigations will, it seems, focus on the prevalence and the clinical implications of MRSA CC398 in other segments of the population which are at risk, such as pig slaughter-house workers and the population in general in the area of Osona.

Background: MRSA or Methicillin-resistant Staphylococcus aureus consists of several strains in the bacterial species called Staphylococcus aureus. MRSA is resistant to methicillin but also to other types of antibiotics. Spread can occur both directly between humans and between humans and animals, but also indirectly through air. The number of positive bacterial cultures for MRSA in Sweden increases every year. The prevalence of MRSA of different types varies in different countries. LA-MRSA is a livestock-associated methicillin-resistant Staphylococcus aureus that was first discovered in the Netherlands in pigs. This bacterial type belongs to a specific clone called CC398 (clonal complex 398), were most belonged to a specific sequence type called ST398 (multi locus sequence type 398). The CC398 strain are constantly acquiring new features including virulence factors such as the PVL-gene has been reported and associated with serious infections in humans and animals. This specific bacterial clone is found primarily in food producing animals around Europe, and it can infect humans and cause infection. It occurs mainly in pigs and can be spread through contaminated pork or other meat products to humans. Purpose: This work was aimed to survey the prevalence of LA-MRSA in the countries from which Sweden imports most meat from and to review the spread from meat products. Method: This study is been based on information on antibiotic use among food producing animals and the proportion of reported cases of MRSA in the countries from which meat was imported. Scientific studies in all countries was used to obtain information on the prevalence of MRSA CC/ST 398 and on its characteristics. Results: The countries from which Sweden imports most meat are Germany, Denmark and the Netherlands, pork import dominates. In 2018 there were 27,260 tonnes of pork imported from Denmark and 45,197 tonnes from Germany, compared with imports from the Netherlands, which amounted to 6,888 tonnes. Germany has the highest antibiotic consumption and the highest proportion of reported cases of MRSA among these countries. In Denmark, the CC/ST 398-clone caused 17 blood infections and 700 skin and soft tissue infections between 2010 and 2015. In Germany, 166 of 330 pigs examined in 2012 were positive for the same clone, as was 77 of the 134 collected samples from the environment and 39 of the 63 animal caretakers. In Brazil, CC / ST398 was found in 6 of 1852 children, genotypic characterization indicated it was an MSSA (methicillin-sensitive S. aureus) CC398 that had acquired SCCmec genes in the health care system. In Italy 81 of 215 pig isolates collected were positive for MRSA where the dominant type was CC / ST398. Virulence genes associated with human MRSA strains such as enterotoxin and PVL genes were not present among the pig isolates. Resistance to tetracycline was seen in all pig isolates. In the Netherlands, MRSA CC / ST398 was linked to pigs in that sense that the humans that were infected were exposed to pigs on a daily basis. Conclusion: The prevalence of LA-MRSA CC / ST398 was high in all the countries surveyed. Resistance to tetracyclines was significantly higher among pig isolates compared to HA-MRSA isolates (healthcare-associated MRSA), whereas the virulence genes such as the PVL- gene usually not present detected in pig- isolates. Among strains identified as LA-MRSA CC / ST398 acquired SCCmec-genes were of types V and IV.  The spread from pigs or meat was through direct contact but also through air.

碩士
大葉大學
管理學院碩士在職專班
102
Owning a house is a basic necessity . In recent years, the prices of houses are keep going up but the salaries are still the same as ten years ago, now buying a house is very difficult. ”High house price” has become the Taiwan people’s grievance. Government’s fiscal policy on the domestic real estate market will inevitably have a major impact. Tax changes and adjustment will also give the real estate market changes in supply and demand. In order to combat speculators invest the gradually rising house price and increase national revenue, the government launch a new strategy – luxury tax. This study analysis about five metropolitan areas of high house price impact factor during implementation of luxury tax three- year period. According to the data of Taiwan real estate transaction center, this study obtained 15392 samples from five metropolitan residents. In view of hedonic price theory ,study the factors affecting the real estate transaction, and establish house price predictive modeling. Through the empirical analysis find that floor space, year of construction, building types and variables such as total floors, all has a significant impact on house price, and the double-logarithmic hedonic price model has a better explanatory power. Implementation of the luxury tax can help curb the trading with price and volume in northern and central region. The southern region is less affected.

碩士
國立中興大學
生命科學系所
104
Mangroves distribute in estuary and coastal region, and mangroves are one of the most important carbon sinks. Mangrove thinning or afforestation has been initiated in many countries because of its negative effects on biodiversity and flood prevention in estuarine ecosystems. However, this may reduce its function as carbon sequestration. Our study tried to quantify mangrove carbon budget and examine the relationship between tree density and carbon sequestration after thinning. We conducted a field study from February 2014 in Fangyuan, Changhua, at 3 sites, including Avicennia marina at seaward zone (SA) and landward zone (LA) and Kandelia obovata (K). Each site was conducted 3 treatments of thinning, including non-thinning as the control (C), medium thinning (MT) by cutting half number of trees, and high thinning (HT) by leaving only one tree in the center. Net primary production and carbon sequestration of mangroves were estimated by the summation method. The results showed that carbon sequestration was 15.4, 14.7, 27.6 Mg C ha-1 yr-1 (in SA, LA, and K, respectively), and carbon stock was 434, 607, 533, Mg C ha-1. These data indicate that Fangyuan mangrove function as carbon sequestration. The estimated net ecosystem production of Fangyuan mangrove was 5.03, 4.38, 19.27 Mg C ha-1 yr-1 (in SA, LA, and K, respectively). Carbon sequestration was lower in MT treatment (11.6, 14.3 and 19.2 Mg C ha-1 yr-1 in SA, LA, and K respectively) and lowest in HT treatment (4.4, 5.0, and 4.5 Mg C ha-1 yr-1). HT treatment reduced areal carbon sequestration, but MT and C treatments had no significant difference. Furthermore, the results showed that individual carbon sequestration was highest in HT treatment (3.6, 4.8, and 1.9 Mg C tree-1 yr-1 in SA, LA, and K respectively). Individual carbon sequestration in HT treatment was significantly higher than that in MT and C treatment. Overall, Fangyuan mangroves was important carbon sinks. Because mangrove afforestation may destroy ecosystem function, we suggest that MT treatment would be the best choice if we are to reduce the loss of carbon sequestration in whole mangrove ecosystem.

Dissertação de Mestrado em Biotecnologia para as Ciências da Saúde apresentada à Universidade de Trás-os-Montes e Alto Douro
O uso de antibióticos aumentou a pressão seletiva nas espécies bacterianas, tornando-as cada vez mais resistentes a estes compostos, sendo a resistência antimicrobiana uma ameaça crescente ao tratamento de infeções causadas por microrganismos. Staphylococcus aureus é uma bactéria versátil que está a tornar-se cada vez mais resistente aos antibióticos, sendo hoje S. aureus resistente à meticilina, MRSA, um problema de saúde pública, pois são encontrados em hospitais, na comunidade e no gado. Existem diversos clones em circulação sendo um dos mais comuns na população suína, o MRSA CC398. Este trabalho consistiu na recolha de amostras de carcaças de suínos de matadouros com sinais visíveis de infeção, para a identificação, deteção e caracterização genética e molecular das estirpes de MRSA e Staphylococcus aureus suscetíveis à meticilina, MSSA, encontradas. A identificação das espécies foi efetuada por técnicas microbiológicas, testes bioquímicos, pela técnica de PCR e MALDI Biotyper®. Foram identificados 28 S. aureus que foram submetidos à identificação fenotípica da resistência aos antibióticos, procedendo-se de seguida à caracterização molecular, com a determinação dos genes de resistência dos antibióticos testados, assim como tipificação molecular e a presença de genes de virulência, genes do cluster de evasão do sistema imunitário humano (IEC) e bacteriófagos. Obtiveram-se 22 MRSA CC398 (20%) e 6 MSSA ST1 (8%), das 141 amostras recolhidas de suínos com sinais de infeção ao nível do matadouro. Estas estirpes apresentaram fenótipos de multirresistência, contudo todas apresentaram sensibilidade aos antibióticos linezolide, vancomicina, mupirocina e ácido fusídico que poderão ser úteis na eliminação deste microrganismo. Apesar disto, carecem da maioria dos genes de virulência, com exceção das hemolisinas, assim como ausência do sistema IEC, de acordo com a sua origem animal, ou seja, não é tão virulenta. Nos estudos moleculares, nas estirpes MRSA CC398 foi possível identificar spa tipos t1451, t011 e t108, com variação do SCCmec em tipos IVa e V, com agrI; já nas MSSA ST1, foi encontrado spa t1491 e agrIII. Os resultados permitem concluir que MRSA CC398 não é apenas um colonizador habitual de suínos, mas também um patógeno oportunista. Os suínos poderão ser considerados um reservatório de novas resistências e, como tal, deve ser controlado ao nível dos produtores e matadouros devido ao seu impacto na saúde pública.
The use of antibiotics raised the selective pressure over bacterial species, making them increasingly resistant to these compounds, being antimicrobial resistance an elevated treat to the treatment of injections caused by microorganisms. Staphylococcus aureus is a versatile bacterium that is becoming increasingly resistant to antibiotics, being methicillin-resistant S. aureus, MRSA, a public health issue, as they are found in hospitals, in the community and in livestock. There are several circulating clones being one of the most common in the swine population, MRSA CC398. This work consisted in the collection of samples of swine carcasses from slaughterhouses with visible signs of infection for identification, detection and genetic and molecular characterization of the MRSA and methicillin-susceptible Staphylococcus aureus, MSSA, strains found. The identification of the species was carried out by microbiological techniques, biochemical tests, by PCR technique and MALD Biotyper®. A total of 28 S. aureus were identified, which were submitted to the phenotypic identification of resistance to antibiotics, followed by molecular characterization, determination of resistance genes of the antibiotics tested, as well as molecular typing and the presence of virulence genes, genes of IEC and bacteriophages. Twenty-two MRSA CC398 (20%) and six MSSA ST1 (8%) of the 141 samples collected from swine with signs of infection at the slaughterhouse level were obtained. These strains showed multiresistant phenotypes, however, all of them showed sensitivity to linezolid, vancomycin, mupirocin and fusidic acid antibiotics that may be useful in the elimination of this microorganism. In spite of this, they lack most virulence genes, with exception of hemolysins, as well as absence of the immune evasion cluster (IEC) system, according to their animal origin, that is, it is not that virulent. Regarding the molecular studies, in the MRSA CC398 strains it was possible to identify spa types t1451, t011 and t108, with variation of the SCCmec in types Iva and V, with agrI; while in MSSA ST1, was found spa t1491 and agrIII. The results allow to conclude that MRSA CC398 is not only a habitual pig colonizer, but also an opportunistic pathogen. Pigs may be considered as a reservoir of new resistances and such must be controlled at producers and slaughterhouse levels because of their impact in public health.