Caracterização genética de Staphylococcus aureus suscetíveis e resistentes à meticilina (MSSA e MRSA, respetivamente) de amostras provenientes de suínos de matadouro
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2019-02-11
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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.
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.
Descrição
Dissertação de Mestrado em Biotecnologia para as Ciências da Saúde apresentada à Universidade de Trás-os-Montes e Alto Douro
Palavras-chave
MRSA CC398 , suínos , alimentação , saúde pública