Resistência a antibióticos em Staphylococcus aureus isolados da cavidade oral de pacientes submetidos a tratamento médico-dentário
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2021-03-22
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Staphylococcus aureus é uma bactéria Gram-positiva que coloniza naturalmente o ser humano em várias partes do corpo, nomeadamente na cavidade oral. Apesar desta bactéria não estar diretamente envolvida no processo de formação da cárie dentária, é reconhecida como um dos mais importantes agentes patogénicos oportunistas humanos, capaz de causar diversas doenças de diferentes graus de severidade. A patogenicidade de S. aureus está relacionada com a secreção de uma panóplia de proteínas e toxinas que lhe permitem evadir a resposta do sistema imunitário. Para além disso, a aquisição de mecanismos de resistência a antibióticos por parte destas bactérias levou à emergência de estirpes bacterianas resistentes, constituindo um grave problema a nível mundial. Assim sendo, o objetivo deste trabalho é caracterizar fenotipicamente S. aureus provenientes da cavidade oral de pacientes submetidos a tratamento médico-dentário. Trinta e três estirpes foram isoladas de pacientes de uma clínica dentária e a sua suscetibilidade foi testada pelo método de difusão em disco Kirby-Bauer contra 14 agentes antimicrobianos e de acordo com as diretrizes do EUCAST (2018). Os agentes antimicrobianos utilizados foram penicilina, gentamicina, mupirocina, cefotoxina, ciprofloxacina, eritromicina, ácido fusídico, clindamicina, linezolida, tobramicina, canamicina, timetroprim-sulfametoxazol, tetraciclina e cloranfenicol. Os isolados apresentaram resistência à gentamicina (CN, n=29), tobramicina (TOB, n=26), penicilina (PEN, n=16), eritromicina (ERY, n=9), ácido fusídico (FD, n=5), cefoxitina (FOX, n=2), canamicina (K, n=2), ciprofloxacina (CIP, n=1), clindamicina (DA, n=1), e tetraciclina (TET, n=1). Nenhum dos isolados apresentou resistência fenotípica aos antibióticos trimetoprim-sulfametoxazol, mupirocina, cloranfenicol e Linezolida. Todos os isolados foram também testados contra dois antissépticos orais disponíveis comercialmente, porém, os resultados obtidos foram pouco conclusivos. Conclui-se que trabalhos como este são de grande relevo na medida que nos permitem tomar consciência da importância do conhecimento das características de cada estirpe bacteriana em particular e dos seus padrões de suscetibilidade antimicrobiana, de modo a facilitar a escolha da melhor terapia antimicrobiana, evitando assim o uso indevido dos antibióticos, um dos principais fatores que leva à emergência das resistências.
Staphylococcus aureus is a Gram-positive bacterium that naturally colonizes human beings in various parts of the body, namely in the oral cavity. Although this bacterium is not directly involved in the process of dental caries formation, it is recognized as one of the most important human opportunistic pathogens, capable of causing different diseases of different degrees of severity.The pathogenicity of S.aureus is related to the secretion of a panoply of proteins and toxins that allow it to evade the immune system's response. In addition, the acquisition of antibiotic resistance mechanisms by these bacteria has led to the emergence of resistant bacterial strains, constituting a serious problem worldwide. Therefore, the aim of this work is to phenotypically characterize Staphylococcus aureus from the oral cavity of patients undergoing medical and dental treatment. Thirty-three isolates were recovered from patients at a dental clinic and their susceptibility was tested by the Kirby-Bauer disk diffusion method against 14 antimicrobial agents and according to EUCAST guidelines (2018). The antimicrobial agents used were penicillin, gentamicin, mupirocin, cefotoxin, ciprofloxacin, erythromycin, fusidic acid, clindamycin, linezolid, tobramycin, kanamycin, timetroprim-sulfamethoxazole, tetracycline and chloramphenicol. The isolates showed resistance to gentamicin (CN, n = 29), tobramycin (TOB, n = 26), penicillin (PEN, n = 16), erythromycin (ERY, n = 9), fusidic acid (FD, n = 5) , cefoxitin (FOX, n = 2), kanamycin (K, n = 2), ciprofloxacin (CIP, n = 1), clindamycin (DA, n = 1), and tetracycline (TET, n = 1). None of the isolates showed phenotypic resistance to the antibiotics trimethoprim-sulfamethoxazole, mupirocin, chloramphenicol and Linezolid. All the isolates were also tested against two commercially available oral antiseptics, however, the results obtained were not conclusive. It is concluded that works like this are of great relevance in the way they allow us to become aware of the importance of knowing the characteristics of each bacterial strain in particular and its patterns of antimicrobial susceptibility, in order to facilitate the choice of the best antimicrobial therapy, avoiding thus the misuse of antibiotics, one of the main factors that leads to the emergence of resistance.
Staphylococcus aureus is a Gram-positive bacterium that naturally colonizes human beings in various parts of the body, namely in the oral cavity. Although this bacterium is not directly involved in the process of dental caries formation, it is recognized as one of the most important human opportunistic pathogens, capable of causing different diseases of different degrees of severity.The pathogenicity of S.aureus is related to the secretion of a panoply of proteins and toxins that allow it to evade the immune system's response. In addition, the acquisition of antibiotic resistance mechanisms by these bacteria has led to the emergence of resistant bacterial strains, constituting a serious problem worldwide. Therefore, the aim of this work is to phenotypically characterize Staphylococcus aureus from the oral cavity of patients undergoing medical and dental treatment. Thirty-three isolates were recovered from patients at a dental clinic and their susceptibility was tested by the Kirby-Bauer disk diffusion method against 14 antimicrobial agents and according to EUCAST guidelines (2018). The antimicrobial agents used were penicillin, gentamicin, mupirocin, cefotoxin, ciprofloxacin, erythromycin, fusidic acid, clindamycin, linezolid, tobramycin, kanamycin, timetroprim-sulfamethoxazole, tetracycline and chloramphenicol. The isolates showed resistance to gentamicin (CN, n = 29), tobramycin (TOB, n = 26), penicillin (PEN, n = 16), erythromycin (ERY, n = 9), fusidic acid (FD, n = 5) , cefoxitin (FOX, n = 2), kanamycin (K, n = 2), ciprofloxacin (CIP, n = 1), clindamycin (DA, n = 1), and tetracycline (TET, n = 1). None of the isolates showed phenotypic resistance to the antibiotics trimethoprim-sulfamethoxazole, mupirocin, chloramphenicol and Linezolid. All the isolates were also tested against two commercially available oral antiseptics, however, the results obtained were not conclusive. It is concluded that works like this are of great relevance in the way they allow us to become aware of the importance of knowing the characteristics of each bacterial strain in particular and its patterns of antimicrobial susceptibility, in order to facilitate the choice of the best antimicrobial therapy, avoiding thus the misuse of antibiotics, one of the main factors that leads to the emergence of resistance.
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Mestrado em Biologia Clínica Laboratorial
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Resistência a antibióticos , Staphylococcus aureus