Prevalence and virulence characteristics of Aeromonas species isolated from fish farms in Egypt

Abstract

Background/Objective: Fish is one of the most valuable food for human consumption. However, fish may also act as a source of foodborne pathogens including Aeromonas species which caused a serious threat to a public health concern. This study aimed to investigate the prevalence and virulence characteristics of Aeromonas species isolated from fish farms in Egypt. Methods: A total of 100 random samples of freshwater fish represented by Nile tilapia and Mugil cephalus (50 of each) were collected from different fish farms in Kafr El-Sheikh governorate and examined bacteriologically and biochemically for the presence of Aeromonas species. Multiplex PCR was done to detect some virulence-associated genes in Aeromonas hydrophila isolates. Results: The obtained results revealed that the incidence of Aeromonas species in Nile tilapia and Mugil cephalus were 32 (64%) and 25 (50%), respectively. The most prevalent Aeromonas species isolated from Nile tilapia were Aeromonas caviae 13 (40.6%), Aeromonas hydrophila 8 (25%), Aeromonas sobria 7 (21.9%), Aeromonas veronii 3 (9.4%), and Aeromonas fluvialis 1 (3.1%), while from fresh Mugil cephalus were Aeromonas sobria 11 (44%), Aeromonas caviae 7 (28%), Aeromonas hydrophila 5 (20%), and Aeromonas veronii 2 (8%). The isolated Aeromonas hydrophila concealed some virulence genes responsible for their pathogenicities such as aerolysin gene (aerA) and cytotonic enterotoxin gene (altA). Conclusion: The hygienic measures should be applied to prevent fish contamination with Aeromonas species.

Emergence of extensively drug-resistant Aeromonas hydrophila complex isolated from wild Mugil cephalus (striped mullet) and Mediterranean seawater

“…from various fish species and water in an earlier study [63]. However, alt gene has been detected in A. hydrophila from freshwater M. cephalus in a recent study in Egypt [42]. We failed to detect ast gene in any isolate in the current investigation.…”

“…However, this was not the usual pattern in farmed freshwater fish. In a recent study in Egypt, A. sobria (44%), A. caviae (28%), A. hydrophila (20%), and A. veronii (8%) were the most predominant species from mullet collected from different fish farms in Kafr El-Sheikh governorate [42]. However, another study indicated that A. caviae dominates in seawater fish (7.2%) [43].…”

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

“…Moreover, accidents involving swimming and boating, alligator bites, and fishing hooks have all been considered reasons for infected people with Aeromonas (Janda and Abbott, 1998). The isolated Aeromonas species from Nile tilapia and Mugil cephalus was not only related to the fish pathogens but also concerned with the consumers' health (Kishk et al, 2020). Out of eight virulence factor genes screened, six genes, encoding for cytotoxic enterotoxin (act), enterotoxin (ast), elastase (ela), cytotonic enterotoxin (alt), lipase-like protein (lip), aerolysine (asa), were detected in the A.sobria.…”

“…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). The aerA and altA virulence factor genes were identified with percentages 64.2% and 38.5%, respectively, in A. hydrophila isolates from Nile Tilapia-affected fishes and 30.8% in Mugil cephalus fishes (Kishk et al, 2020). Exotoxins, cytotoxins, cytotonic toxins, dermonecrotic toxins, leucocidins, cytolytic proteins, and hemolysins are exogenous virulence factors that can bind to and enter epithelial cells, which helps to explain how these organisms become pathogens.…”

Molecular characterization of Aeromonas hydrophila isolates from diseased fishes in district Kasur, Punjab, Pakistan

“…The detection of these virulence genes in microbes inhabiting diverse hosts can help in risk assessment of cross species transmission and environmental monitoring for contaminating these genes (Roges et al, 2020). The virulent genes associated with pathogenic strains of A. hydrophila isolated from fish has been detected in Vietnam (aerA, act), Egypt (aerA, altA) and Tanzania (aer, hly, fla) (Kishk et al, 2020;Mzula et al, 2020;Nhinh et al, 2021).…”