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Antibiorresistência e pesquisa de fatores de virulência em Aeromonas spp.
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Os membros do género Aeromonas são reconhecidos como patogéneos emergentes responsáveis por uma vasta panóplia de doenças infeciosas em humanos. Entre as infeções associadas a este género, a gastroenterite é a manifestação clinica mais comum. No presente estudo, pesquisou-se a ocorrência de aeromonas numa fábrica de queijos, num matadouro de suínos e num hipermercado. Foram estudadas 85 amostras, que incluíram amostras de água, de alimentos e de superfícies. A análise dessas amostras permitiu a recuperação de 72 Aeromonas spp., cujo potencial de patogenicidade foi avaliado através da pesquisa de fatores de virulência e perfis de suscetibilidade a 16 agentes antimicrobianos. A análise do potencial patogénico revelou a elevada produção de proteínas extracelulares ativas: DNases (86%), lipases (61%), proteases (93%), e hemolisinas (99%). Relativamente aos genes de virulência, as percentagens mais elevadas foram observadas para act (55%), ahyB (54%), alt (53%) e lip (53%), frequências inferiores a 40% foram observadas para flaA/B, hlyA, ascV, aext, e ast. Na globalidade, os resultados revelam múltiplas combinações de potenciais fatores de virulência entre os isolados em estudo. Quanto à resistência a antibióticos, os níveis mais elevados foram observados para amoxicilina/ácido clavulânico (36%), ácido nalidíxico (29%) e tetraciclina (17%). Níveis mais reduzidos de resistência (<10%) foram detetados para a amicacina, aztreonam, cefotaxima, ceftazidima, ceftriaxona, cloranfenicol, ciprofloxacina, gentamicina, norfloxacina e trimetoprim/ sulfametoxazol. Todos os isolados apresentaram sensibilidade ao imipenem e levofloxacina. Em conclusão, os resultados obtidos revelaram a ampla disseminação de aeromonas potencialmente patogénicas nos diferentes ambientes em estudo, tendo-se detetado fenótipos de resistência a antibióticos clinicamente importantes e diferentes combinações de potenciais fatores de virulência relacionados com a adesão, invasão e disseminação no hospedeiro. No entanto, as estirpes com maior potencial de patogenicidade foram maioritariamente detetadas em ambientes cujos alimentos serão sujeitos a tratamento térmico antes do consumo, reduzindo o risco associado a presença de aeromonas.
Members of the genus Aeromonas are recognized as emerging pathogens responsible for a variety of infectious diseases in humans, gastroenteritis being the most common clinical manifestation. In the present study, the presence of Aeromonas spp. was evaluated in samples collected from a cheese factory, a slaughterhouse and a supermarket. Eighty-five samples from drinking-water, food and food-processing surfaces were studied. The analysis of those samples allowed the isolation of 72 aeromonads and corresponding pathogenicity potential investigated by screening for putative virulence factors and assessment of the susceptibility profiles to 16 antimicrobial agents. A high extracellular production of proteins active, DNases (86%), lipases (61%), proteases (93%) and hemolysins (99%) was observed among the isolates under study. Regarding the presence of virulence genes, the highest frequencies were observed for act (55%), ahyB (54%), alt (53%) and lip (53%) while prevalencies lower than 40% were observed for flaA/B, hlyA, ascV, aext and ast. Overall, the results revealed multiple combinations of putative virulence factors among the isolates under analysis. Regarding the antimicrobial resistance profiles, higher levels of resistance were detected for amoxicillin/clavulanic acid (36%), nalidixic acid (29%) and tetracycline (17%). Lower resistances (<10%) was observed for amikacin, aztreonam, cefotaxime, ceftazidime, ceftriaxone, chloramphenicol, ciprofloxacin, gentamicin, norfloxacin and trimethoprim/sulfamethoxazole. All isolates were susceptible to imipenem and levofloxacin. In conclusion, our results demonstrated a high dissemination of putatively pathogenic aeromonads in the different environments investigated, detected phenotypes of resistance to medically important antibiotics and distinct combinations of genetic determinants for enterotoxins, hemolysins and factors associated with adherence, tissue invasion and spread in the host were identified. However, strains with greater pathogenic potential were identified in environments whose food will undergo heat treatment before consumption, reducing the risk associated with the presence of aeromonads.
Members of the genus Aeromonas are recognized as emerging pathogens responsible for a variety of infectious diseases in humans, gastroenteritis being the most common clinical manifestation. In the present study, the presence of Aeromonas spp. was evaluated in samples collected from a cheese factory, a slaughterhouse and a supermarket. Eighty-five samples from drinking-water, food and food-processing surfaces were studied. The analysis of those samples allowed the isolation of 72 aeromonads and corresponding pathogenicity potential investigated by screening for putative virulence factors and assessment of the susceptibility profiles to 16 antimicrobial agents. A high extracellular production of proteins active, DNases (86%), lipases (61%), proteases (93%) and hemolysins (99%) was observed among the isolates under study. Regarding the presence of virulence genes, the highest frequencies were observed for act (55%), ahyB (54%), alt (53%) and lip (53%) while prevalencies lower than 40% were observed for flaA/B, hlyA, ascV, aext and ast. Overall, the results revealed multiple combinations of putative virulence factors among the isolates under analysis. Regarding the antimicrobial resistance profiles, higher levels of resistance were detected for amoxicillin/clavulanic acid (36%), nalidixic acid (29%) and tetracycline (17%). Lower resistances (<10%) was observed for amikacin, aztreonam, cefotaxime, ceftazidime, ceftriaxone, chloramphenicol, ciprofloxacin, gentamicin, norfloxacin and trimethoprim/sulfamethoxazole. All isolates were susceptible to imipenem and levofloxacin. In conclusion, our results demonstrated a high dissemination of putatively pathogenic aeromonads in the different environments investigated, detected phenotypes of resistance to medically important antibiotics and distinct combinations of genetic determinants for enterotoxins, hemolysins and factors associated with adherence, tissue invasion and spread in the host were identified. However, strains with greater pathogenic potential were identified in environments whose food will undergo heat treatment before consumption, reducing the risk associated with the presence of aeromonads.
Descrição
Tese de mestrado. Biologia (Microbiologia aplicada). Universidade de Lisboa, Faculdade de Ciências, 2013
Palavras-chave
Gastroenterite Resistência aos antibióticos Aeromonas spp. Teses de mestrado - 2013