Virulence-Associated Genes and Antimicrobial Resistance of Aeromonas hydrophila Isolates from Animal, Food, and Human Sources in Brazil

Abstract

Aeromonads are natural inhabitants of aquatic environments and may be associated with various human or animal diseases. Its pathogenicity is complex and multifactorial and is associated with many virulence factors. In this study, 110 selected Aeromonas hydrophila isolates isolated from food, animals, and human clinical material from 2010 to 2015 were analyzed. Antimicrobial susceptibility testing was performed by the disk diffusion method, and polymerase chain reaction was conducted to investigate the virulence genes hemolysin (hlyA), cytotoxic enterotoxin (act), heat-labile cytotonic enterotoxin (alt), aerolysin (aerA), and DNase-nuclease (exu). At least 92.7% of the isolates had one of the investigated virulence genes. Twenty different virulence profiles among the isolates were recognized, and the five investigated virulence genes were observed in four isolates. Human source isolates showed greater diversity than food and animal sources. Antimicrobial resistance was observed in 46.4% of the isolates, and multidrug resistance was detected in 3.6% of the isolates. Among the 120 isolates, 45% were resistant to cefoxitin; 23.5% to nalidixic acid; 16.6% to tetracycline; 13.7% to cefotaxime and imipenem; 11.8% to ceftazidime; 5.9% to amikacin, gentamicin, and sulfamethoxazole-trimethoprim; and 3.9% to ciprofloxacin and nitrofurantoin. Overall, the findings of our study indicated the presence of virulence genes and that antimicrobial resistance in A. hydrophila isolates in this study is compatible with potentially pathogenic bacteria. This information will allow us to recognize the potential risk through circulating isolates in animal health and public health and the spread through the food chain offering subsidies for appropriate sanitary actions.

Detection of Virulence-Associated Genes and in vitro Gene Transfer From Aeromonas sp. Isolated From Aquatic Environments of Sub-himalayan West Bengal

“…Similar results were obtained by Oliviera et al (50) as they found no statistically significant relationship between the presence of virulence factors and mortality in Nile tilapia infected by A. hydrophila. Such absence of correlation between virulence factors and pathogenicity has also been reported by many other researchers (51,52). However, several authors observed that the presence of specific virulence factors in aeromonads is closely related to mortality in injected fishes (9,53).…”

Antibiotic resistance profile and virulence factor genes of Aeromonas sobria isolated from AL-Hillah River in Babel (Iraq)

“…(Sen and Rodgers, 2004) revealed the presence of 6 virulence factor genes in Aeromonas spp., elastase (ahyB), lipase (pla/lip/lipH3/ alp-1) flagella A and B (flaA and flaB), the enterotoxins, act, alt and ast, using PCR and out of 205 isolates, only one isolate including all these virulence genes. However, results by (Roges et al, 2020) indicated that among different sources of A. hydrophila isolates, at least 92.7% presented one of the virulence factor genes and the most variation was identified in human isolates than in food sources and animals. Some extracellular virulence factor genes associated with Aeromonas have been well described including exotoxins, cytotoxins, cytotonic toxins, dermonecrotic toxins, leucocidins, cytolytic proteins, hemolysins which confer the ability to bind to and destroy epithelial cells, to explain the process of pathogenically of these organisms (Hatha et al, 2005;Matyar et al, 2010).…”

Current status and advances of fish vaccines in Malaysia

“…in fish. Some of these virulence factors include exotoxins [82], exoenzymes [83], outer membrane protein (Omp) [84], and quorum sensing-controlled virulence factor [75].…”