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Caracterização e avaliação da eficácia de desinfetantes em isolados bacterianos ambientais
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Advisor(s)
Abstract(s)
Introdução: Os biocidas aplicados em superfícies ajudam a prevenir infeções, mas o uso incorreto pode promover resistência antimicrobiana e disseminar patogénicos resistentes.
Objetivos: Isolar e caracterizar bactérias presentes em superfícies da Egas Moniz School of Health & Science, determinando os seus perfis de resistência a antibióticos; avaliar a eficácia antibacteriana de três desinfetantes utilizados na instituição.
Materiais e métodos: As amostras foram recolhidas com zaragatoas embebidas em água peptonada, incubadas em meio de enriquecimento e posteriormente inoculadas em meios seletivos para isolamento de colónias. A identificação preliminar foi realizada através de testes fenotípicos e bioquímicos, sendo confirmada em alguns casos usando API® e, por PCR em tempo real (qPCR). A suscetibilidade dos isolados obtidos aos antibióticos foi avaliada por difusão em agar. A eficácia dos desinfetantes foi determinada através da concentração mínima inibitória (CMI), usando o método de microdiluição, com estirpes de referência e três isolados, um de Escherichia coli e dois de Staphylococcus spp.
Resultados: Foram obtidos 24 isolados: E. coli (n=3), Pseudomonas aeruginosa (n=2), Staphylococcus spp. (n=12, dos quais 9 eram manitol-negativo e coagulase-negativo) e Enterococcus spp. (n=7). A identificação definitiva foi levada a cabo para 5 isolados, sendo três E. coli e dois Enterococcus faecium. Observou-se baixa resistência a antibióticos, sem casos de multirresistência. O isolado de E. coli e os dois de Staphylococcus coagulase-negativo apresentaram suscetibilidade aos desinfetantes semelhante às estirpes de referência. O qPCR identificou genes de resistência à meticilina em alguns isolados, e excluiu a presença S. aureus. Os valores de CMI dos desinfetantes situaram-se dentro dos valores reportados na literatura para as espécies testadas.
Conclusão: Os resultados sugerem uma aplicação eficaz dos protocolos de desinfeção e uso criterioso de biocidas na instituição. Contudo, recomenda-se vigilância microbiológica contínua para deteção precoce de alterações nos perfis de resistência e na microbiota ambiental.
Introduction: Biocides applied to surfaces help prevent infections, but incorrect use can promote antimicrobial resistance and spread resistant pathogens. Objectives: To isolate and characterise bacteria present on surfaces at the Egas Moniz School of Health & Science, determining their antibiotic resistance profiles; to evaluate the antibacterial efficacy of three disinfectants used at the institution. Materials and methods: Samples were collected with swabs soaked in peptone water, incubated in enrichment medium and subsequently inoculated in selective media for colony isolation. Preliminary identification was performed using phenotypic and biochemical tests, confirmed in some cases using API® and real-time PCR (qPCR). The susceptibility of the isolates to antibiotics was assessed by agar diffusion. The efficacy of the disinfectants was determined by the minimum inhibitory concentration (MIC) using the microdilution method with reference strains and three isolates, one Escherichia coli and two Staphylococcus spp. Results: Twenty-four isolates were obtained: E. coli (n=3), Pseudomonas aeruginosa (n=2), Staphylococcus spp. (n=12, of which 9 were mannitol-negative and coagulase-negative) and Enterococcus spp. (n=7). Definitive identification was carried out for 5 isolates, three of which were E. coli and two Enterococcus faecium. Low resistance to antibiotics was observed, with no cases of multidrug resistance. The E. coli isolate and the two coagulase-negative Staphylococcus isolates showed similar susceptibility to disinfectants as the reference strains. qPCR identified methicillin resistance genes in some isolates and ruled out the presence of S. aureus. The MIC values of the disinfectants were within the values reported in the literature for the species tested. Conclusion: The results suggest effective application of disinfection protocols and judicious use of biocides in the institution. However, continuous microbiological surveillance is recommended for early detection of changes in resistance profiles and environmental microbiota.
Introduction: Biocides applied to surfaces help prevent infections, but incorrect use can promote antimicrobial resistance and spread resistant pathogens. Objectives: To isolate and characterise bacteria present on surfaces at the Egas Moniz School of Health & Science, determining their antibiotic resistance profiles; to evaluate the antibacterial efficacy of three disinfectants used at the institution. Materials and methods: Samples were collected with swabs soaked in peptone water, incubated in enrichment medium and subsequently inoculated in selective media for colony isolation. Preliminary identification was performed using phenotypic and biochemical tests, confirmed in some cases using API® and real-time PCR (qPCR). The susceptibility of the isolates to antibiotics was assessed by agar diffusion. The efficacy of the disinfectants was determined by the minimum inhibitory concentration (MIC) using the microdilution method with reference strains and three isolates, one Escherichia coli and two Staphylococcus spp. Results: Twenty-four isolates were obtained: E. coli (n=3), Pseudomonas aeruginosa (n=2), Staphylococcus spp. (n=12, of which 9 were mannitol-negative and coagulase-negative) and Enterococcus spp. (n=7). Definitive identification was carried out for 5 isolates, three of which were E. coli and two Enterococcus faecium. Low resistance to antibiotics was observed, with no cases of multidrug resistance. The E. coli isolate and the two coagulase-negative Staphylococcus isolates showed similar susceptibility to disinfectants as the reference strains. qPCR identified methicillin resistance genes in some isolates and ruled out the presence of S. aureus. The MIC values of the disinfectants were within the values reported in the literature for the species tested. Conclusion: The results suggest effective application of disinfection protocols and judicious use of biocides in the institution. However, continuous microbiological surveillance is recommended for early detection of changes in resistance profiles and environmental microbiota.
Description
Dissertação para obtenção do grau de Mestre no Instituto Universitário Egas Moniz
Keywords
Biocidas Resistência antimicrobiana Desinfetantes Isolados ambientais