Cross-sectional analysis of risk factors associated with Mugil cephalus in retail fish markets concerning methicillin-resistant Staphylococcus aureus and Aeromonas hydrophila.

Introduction: Aeromonas hydrophila and methicillin-resistant Staphylococcus aureus (MRSA) are potent bacterial pathogens posing major hazards to human health via consuming fish harboring these pathogens or by cross-contamination beyond the contaminated environment. The aim of this study was to determine risk variables associated with the presence of certain pathogenic bacteria from Mugil cephalus fish in retail markets in Egypt. The virulence genes of A. hydrophila and S. aureus were also studied. Furthermore, the antibiotic sensitivity and multidrug resistance of the microorganisms were evaluated. Methods: In a cross-sectional investigation, 370 samples were collected from mullet skin and muscle samples, washing water, fish handlers, knives, and chopping boards. Furthermore, fish handlers' public health implications were assessed via their response to a descriptive questionnaire. Results: S. aureus and Aeromonas species dominated the investigated samples with percentages of 26.76% and 30.81%, respectively. Furthermore, A. hydrophila and MRSA were the predominant recovered bacterial pathogens among washing water and knives (53.85% and 46.66%, respectively). The virulence markers aerA and hlyA were found in 90.7% and 46.5% of A. hydrophila isolates, respectively. Moreover, the virulence genes nuc and mec were prevalent in 80% and 60% of S. aureus isolates, respectively. Antimicrobial susceptibility results revealed that all A. hydrophila isolates were resistant to amoxicillin and all MRSA isolates were resistant to amoxicillin and ampicillin. Remarkably, multiple drug resistance (MDR) patterns were detected in high proportions in A. hydrophila (88.37%) and MRSA (100%) isolates. The prevalence of Aeromonas spp. and S. aureus had a positive significant correlation with the frequency of handwashing and use of sanitizer in cleaning of instruments. MRSA showed the highest significant prevalence rate in the oldest age category. Conclusion: The pathogenic bacteria recovered in this study were virulent and had a significant correlation with risk factors associated with improper fish handling. Furthermore, a high frequency of MDR was detected in these pathogenic bacteria, posing a significant risk to food safety and public health.

Development of a surface plasmon resonance (SPR) assay for rapid detection of Aeromonas hydrophila.

Aquaculture plays an increasingly important if not critical role in the current and future world food supply. Aeromonas hydrophila, a heterotrophic, Gram-negative, bacterium found in fresh or brackish water in warm climates poses a serious threat to the aquaculture industry in many areas, causing significant economic losses. Rapid, portable detection methods of A. hydrophila are needed for its effective control and mitigation. We have developed a surface plasmon resonance (SPR) technique to detect PCR (polymerase chain reaction) products that can replace agarose gel electrophoresis, or otherwise provide an alternative to costlier and more complicated real-time, fluorescence-based detection. The SPR method provides sensitivity comparable to gel electrophoresis, while reducing labor, cross-contamination, and test time, and employs simpler instrumentation with lower cost than real-time PCR.

Aerolysin gene characterization and antimicrobial resistance profile of Aeromonas hydrophila isolated from milkfish (Chanos chanos) in Gresik, Indonesia.

Background and Aim: Motile Aeromonas septicemia is a crucial disease in freshwater fish. Aeromonas hydrophila is a disease agent associated with sporadic fish mortality, food safety, and public health. This study aimed to estimate the prevalence and the presence of the aerolysin gene and antimicrobial resistance profile of A. hydrophila isolated from milkfish in Gresik, Indonesia. Materials and Methods: A total of 153 milkfish gill samples were collected from 16 locations in Gresik and then cultured and identified using biochemical tests. The aerolysin gene was investigated using a polymerase chain reaction, and antimicrobial resistance profiles of the recovered isolates were investigated. Results: Of the 153 examined samples, 35 (22.9%) were confirmed positive for A. hydrophila and 22 (62.9%) presented the aerolysin gene. The recovered isolates were resistant to the following antibiotics: Amoxicillin (62.9%), tetracycline (60%), streptomycin (54.3%), cefotaxime (51.4%), gentamycin (31.4%), kanamycin (28.6%), erythromycin (25.7%), chloramphenicol (20%), and trimethoprim (14.3%). Meanwhile, only ciprofloxacin, nalidixic acid, and imipenem were indicated as susceptible. Conclusion: The presence of the aerolysin gene is vital in determining the virulence of A. hydrophila. The study results indicated a high aerolysin gene prevalence. In addition, this study emphasized antibiotic use monitoring, food safety improvement, and negative impact reduction on human health and the environment.

Diversity in gene arrangement in a DNA region lacking aerA in clinical and environmental Aeromonas hydrophila isolates.

Aquatic pathogen Aeromonas hydrophila produces an array of virulence factors, many of which are excreted proteins that causes infectious disease in fish, reptiles, and humans. Aerolysin, a haemolytic toxin, is the most well-known of the A. hydrophila virulence factors and is encoded by aerA. Although used as a virulence gene marker in several studies, recent whole-genome sequencing data suggest there may be some variation in aerolysin genes, as well as in the genetic environment of these genes, among A. hydrophila strains. Here, we used PCR-based assays to examine gene arrangement in the traditional aerA region of 42 aerA-minus clinical and environmental A. hydrophila isolates. PCR primers were designed based on known genes from within the target regions of reference strains carrying non-aerA aerolysin genes. Analyses revealed four different gene arrangement patterns among the isolates, indicating considerable genetic diversity in the target region. While 19 of the 21 environmental isolates showed the same gene pattern, all four patterns were represented among the clinical isolates, implying that the gene pattern is highly conserved in the target region among environmental isolates. Further analysis of the gene regions showed that the predominant pattern among environmental isolates, which did not contain an aerolysin gene, appeared to be the progenitor of the other three patterns, which likely arose as a result of gene acquisition, deletion, and rearrangement events during the evolution of A. hydrophila, and may be linked to the acquisition of aerolysin genes. These findings shed light on the evolution of virulence in A. hydrophila.