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Background and Aim: Antibiotic resistance has been a progressively documented problem, resulting in treatment failure in humans and animals. This study aimed to investigate the antimicrobial susceptibility and virulence of extensively drug-resistant (XDR) Aeromonas spp. in wild Mugil cephalus and its surrounding seawater along the coastal road of Port Said, Egypt. Materials and Methods: Specimens were examined bacteriologically, confirmed biochemically, and tested for their sensitivity against 11 antimicrobial agents. Molecular confirmation of the obtained isolates by 16S rRNA was performed, followed by the detection of antimicrobial resistance and virulence genes. Results: Aeromonas spp. was recovered from fish (44%) and water samples (36%). A. hydrophila was the most prevalent identified strain, followed by Aeromonas sobria, Aeromonas caviae, and Aeromonas schubertii. Moreover, 90% of the tested isolates were multidrug-resistant (MDR), while 26.67% were XDR. Tested isolates were resistant to β-lactams and sulfonamides (100%), oxytetracycline (90%), and streptomycin (62.22%) but completely susceptible to cefotaxime. XDR isolates successfully amplified resistance genes (blaTEM, sul1, and tetA(A)) but not the (aadA1) gene, although there was phenotypic resistance to streptomycin on plates. All XDR isolates carry the cytotoxic enterotoxin gene (act), but alt gene was detected in only one isolate (12.5%). Conclusion: Data in this study provide a recent update and highlight the role of wild mullet and seawater as reservoirs for MDR and XDR Aeromonas spp. that may pose a risk to humans as food-borne infection or following direct contact.

This study was conducted to investigate the prevalence, antimicrobial susceptibility, and molecular characterization of Aeromonas spp. from wild Nile tilapia from Lake Manzala and the lake water. Swabs from the surface, gills, and internal organs of apparently healthy Nile tilapia (n =100) and lake water (n = 25) were collected and examined bacteriologically for the presence of Aeromonas spp. The isolates obtained were tested for their susceptibility to 11 antimicrobial agents using the disk diffusion method. The presence of antibiotic resistance genes (blaTEM, sul1, tetA(A), and aadA1) and virulence genes (enterotoxins) (alt, ast, and act) was determined using conventional polymerase chain reaction. Overall, Aeromonas spp. were recovered from 69% of Nile tilapia (Oreochromis niloticus) samples and 80% of water samples. Four types of aeromonads were detected in all the samples examined, namely, A. hydrophila, A. sobria, A. caviae, and A. schubertii, with A. hydrophila predominating in both the fish and the lake water samples. The antimicrobial resistance profiles of the isolates showed very high resistance to ampicillin, penicillin, sulfamethoxazole/trimethoprim, and oxytetracycline and considerable resistance to streptomycin. However, all isolates were sensitive to cefotaxime. Molecular characterization revealed the presence of the act (100%) and alt (37.5%) genes, but ast was not found in any of the isolates. Specific amplification bands of the antimicrobial resistance genes blaTEM, sul1, and tetA(A) were detected in all the tested isolates, whereas aadA1 (12.5%) was found only in one isolate of A. hydrophila from Nile tilapia. The presence of these enterotoxigenic and resistant Aeromonas spp. in the fish and water samples from Lake Manzala could pose a potential public health threat to human consumers and fish handlers in the study area; moreover, these species carry a risk for the transfer of resistance genes to other microbial communities in the lake [ABSTRACT FROM AUTHOR]

Background and Aim: Antibiotic resistance has been a progressively documented problem, resulting in treatment failure in humans and animals. This study aimed to investigate the antimicrobial susceptibility and virulence of extensively drug-resistant (XDR) Aeromonas spp. in wild Mugil cephalus and its surrounding seawater along the coastal road of Port Said, Egypt. Materials and Methods: Specimens were examined bacteriologically, confirmed biochemically, and tested for their sensitivity against 11 antimicrobial agents. Molecular confirmation of the obtained isolates by 16S rRNA was performed, followed by the detection of antimicrobial resistance and virulence genes. Results: Aeromonas spp. was recovered from fish (44%) and water samples (36%). A. hydrophila was the most prevalent identified strain, followed by Aeromonas sobria, Aeromonas caviae, and Aeromonas schubertii. Moreover, 90% of the tested isolates were multidrug-resistant (MDR), while 26.67% were XDR. Tested isolates were resistant to β-lactams and sulfonamides (100%), oxytetracycline (90%), and streptomycin (62.22%) but completely susceptible to cefotaxime. XDR isolates successfully amplified resistance genes (blaTEM, sul1, and tetA(A)) but not the (aadA1) gene, although there was phenotypic resistance to streptomycin on plates. All XDR isolates carry the cytotoxic enterotoxin gene (act), but alt gene was detected in only one isolate (12.5%). Conclusion: Data in this study provide a recent update and highlight the role of wild mullet and seawater as reservoirs for MDR and XDR Aeromonas spp. that may pose a risk to humans as food-borne infection or following direct contact. [ABSTRACT FROM AUTHOR]

Aeromonas are autochthonous inhabitants of aquatic environments, including chlorinated and polluted waters, although they can also be isolated from a wide variety of environmental and clinical sources. They cause infections in vertebrates and invertebrates and are considered to be an emerging pathogen in humans, producing intestinal and extra-intestinal diseases. Most of the clinical isolates correspond to A. hydrophila, A. caviae, and A. veronii bv. Sobria, which are described as the causative agents of wound infections, septicaemia, and meningitis in immunocompromised people, and diarrhoea and dysenteric infections in the elderly and children. The pathogenic factors associated with Aeromonas are multifactorial and involve structural components, siderophores, quorum-sensing mechanisms, secretion systems, extracellular enzymes, and exotoxins. In this study, we analysed a representative number of clinical and environmental strains belonging to the A. hydrophila species complex to evaluate their potential pathogenicity. We thereby detected their enzymatic activities and antibiotic susceptibility pattern and the presence of virulence genes ( aer, alt, ast, and ascV). The notably high prevalence of these virulence factors, even in environmental strains, indicated a potential pathogenic capacity. Additionally, we determined the adhesion capacity and cytopathic effects of this group of strains in Caco-2 cells. Most of the strains exhibited adherence and caused complete lysis. [ABSTRACT FROM AUTHOR]