RESUMEN
The present study aimed to isolate Aeromonas from fish sold in the markets as well as in sushi and seafood shops and compare their virulence factors and antimicrobial characteristics with those of clinical isolates. Among the 128 fish isolates and 47 clinical isolates, Aeromonas caviae, A. dhakensis, and A. veronii were the principal species. A. dhakensis isolates carried at least 5 virulence genes, more than other Aeromonas species. The predominant genotype of virulence genes was hlyA lip alt col ela in both A. dhakensis and A. hydrophila isolates, alt col ela in A. caviae isolates, and act in A. veronii isolates. A. dhakensis, A. hydrophila, and A. veronii isolates more often exhibited hemolytic and proteolytic activity and showed greater virulence than A. caviae isolates in Caenorhabditis elegans and the C2C12 cell line. However, the link between the genotypes and phenotypes of the studied virulence genes in Aeromonas species was not evident. Among the four major clinical Aeromonas species, nearly all (99.0%) A. dhakensis, A. hydrophila, and A. veronii isolates harbored blaCphA, which encodes a carbapenemase, but only a minority (6.7%, 7/104) were nonsusceptible to carbapenem. Regarding AmpC ß-lactamase genes, blaAQU-1 was exclusively found in A. dhakensis isolates, and blaMOX3 was found only in A. caviae isolates, but only 7.6% (n = 6) of the 79 Aeromonas isolates carrying blaAQU-1 or blaMOX3 exhibited a cefotaxime resistance phenotype. In conclusion, fish Aeromonas isolates carry a variety of combinations of virulence and ß-lactamase resistance genes and exhibit virulence phenotypes and antimicrobial resistance profiles similar to those of clinical isolates.IMPORTANCEAeromonas species can cause severe infections in immunocompromised individuals upon exposure to virulent pathogens in the environment, but the characteristics of environmental Aeromonas species remain unclear. Our study showed that several pathogenic Aeromonas species possessing virulence traits and antimicrobial resistance similar to those of Aeromonas isolates causing clinical diseases were present in fish intended for human consumption in Tainan City, Taiwan.
Asunto(s)
Aeromonas/clasificación , Aeromonas/genética , Aeromonas/aislamiento & purificación , Peces/microbiología , Genotipo , Fenotipo , Alimentos Marinos/microbiología , Aeromonas/efectos de los fármacos , Anciano , Anciano de 80 o más Años , Animales , Antibacterianos/farmacología , Proteínas Bacterianas/genética , Caenorhabditis elegans , Línea Celular , Femenino , Infecciones por Bacterias Gramnegativas/epidemiología , Infecciones por Bacterias Gramnegativas/microbiología , Humanos , Masculino , Pruebas de Sensibilidad Microbiana , Prevalencia , Taiwán/epidemiología , Virulencia/genética , Factores de Virulencia/genética , Resistencia betalactámica/genética , beta-Lactamasas/genéticaRESUMEN
Severe soft tissue infections caused by Aeromonas dhakensis, such as necrotizing fasciitis or cellulitis, are prevalent in southern Taiwan and around the world. However, the mechanism by which A. dhakensis causes tissue damage remains unclear. Here, we found that the haemolysin Ahh1, which is the major virulence factor of A. dhakensis, causes cellular damage and activates the NLR family pyrin domain containing 3 (NLRP3) inflammasome signalling pathway. Deletion of ahh1 significantly downregulated caspase-1, the proinflammatory cytokine interleukin 1ß (IL-1ß) and gasdermin D (GSDMD) and further decreased the damage caused by A. dhakensis in THP-1 cells. In addition, we found that knockdown of the NLRP3 inflammasome confers resistance to A. dhakensis infection in both THP-1 NLRP3-/- cells and C57BL/6 NLRP3-/- mice. In addition, we demonstrated that severe soft-tissue infections treated with antibiotics combined with a neutralizing antibody targeting IL-1ß significantly increased the survival rate and alleviated the degree of tissue damage in model mice compared control mice. These findings show that antibiotics combined with therapies targeting IL-1ß are potential strategies to treat severe tissue infections caused by toxin-producing bacteria.
Asunto(s)
Aeromonas , Infecciones por Bacterias Gramnegativas , Proteínas Hemolisinas , Inflamasomas , Infecciones de los Tejidos Blandos , Animales , Ratones , Aeromonas/metabolismo , Antibacterianos , Caspasa 1/metabolismo , Proteínas Hemolisinas/metabolismo , Inflamasomas/metabolismo , Interleucina-1beta/metabolismo , Macrófagos/metabolismo , Ratones Endogámicos C57BL , Proteína con Dominio Pirina 3 de la Familia NLR/metabolismo , Infecciones de los Tejidos Blandos/inmunología , Infecciones de los Tejidos Blandos/microbiología , Infecciones por Bacterias Gramnegativas/inmunología , Infecciones por Bacterias Gramnegativas/microbiologíaRESUMEN
Paludibacterium species are gram stain-negative rods that are facultatively anaerobic; they have been isolated from wetland soil. Clinical infection caused by this genus is rarely reported. We report the case of an 84-year-old woman with chronic renal disease and hypertension who acquired P. purpuratum lung infection and septicemia in Southern Taiwan.