Investigation of antibiotic-resistant vibrios associated with shrimp (Penaeus vannamei) farms

Knowledge, attitudes and practices on antimicrobial use and antimicrobial resistance among shrimp aquaculturists in Peninsular Malaysia

In aquaculture, production intensification and the increasing occurrence of diseases are equally driving antimicrobial use (AMU) and the development of antimicrobial resistance (AMR). There is inadequate awareness and knowledge regarding AMU and AMR among the public in Malaysia. Thereby, AMR reduction action plans critically require the involvement of farmers as end users of the antimicrobials. The knowledge, attitudes and practices (KAP) survey can evaluate the farmers' awareness level about the issue. To date, no KAP survey has been conducted among shrimp aquaculture farmers in Malaysia regarding AMU and AMR. In addition, no suitable questionnaire is available to conduct the study. Therefore, this study has developed a questionnaire to evaluate the KAP of Penaeus vannamei and Penaeus monodon aquaculture farmers towards AMU and AMR in selected states in Peninsular Malaysia. In total, 113 farmers participated in this survey. The majority (88.1 %, n = 89) of 101 respondents who completed answering the knowledge- and attitude-related KAP items had inadequate knowledge of AMU and AMR. Regarding attitude, the percentages of farmers with good attitudes (49.5 %, n = 50) and poor attitudes (50.5 %, n = 51) are comparable. Nevertheless, a high percentage (95.0 %, n = 96) of them have never used antibiotics on farmed shrimp, indicating good practices in terms of AMU. The Pearson correlation revealed a large positive association between knowledge and attitudes. To the best of our knowledge, this study is the first to develop a questionnaire and assess the KAP regarding AMU and AMR among shrimp aquaculture farmers in Malaysia.

Streptococcus iniae in aquaculture: a review of pathogenesis, virulence, and antibiotic resistance

One of the main challenges in aquaculture is pathogenic bacterial control. Streptococcus iniae stands out for its ability to cause high mortality rates in populations of commercially important fish populations and its recent recognition as an emerging zoonotic pathogen. The rise in identifying over 80 strains some displaying antibiotic resistance coupled with the emerging occurrence of infections in marine mammal species and wild fish underscores the urgent need of understanding pathogenesis, virulence and drug resistance mechanisms of this bacterium. This understanding is crucial to ensure effective control strategies. In this context, the present review conducts a bibliometric analysis to examine research trends related to S. iniae, extending into the mechanisms of infection, virulence, drug resistance and control strategies, whose relevance is highlighted on vaccines and probiotics to strengthen the host immune system. Despite the advances in this field, the need for developing more efficient identification methods is evident, since they constitute the basis for accurate diagnosis and treatment.

Meta-Analysis and Systematic Review of Phenotypic and Genotypic Antimicrobial Resistance and Virulence Factors in Vibrio parahaemolyticus Isolated from Shrimp

This systematic review and meta-analysis investigates the prevalence of Vibrio parahaemolyticus, its virulence factors, antimicrobial resistance (AMR), and its resistance determinants in shrimp. This study was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, to identify and select relevant peer-reviewed articles published between January 2020 and December 2022. The search strategy involved multiple online databases, including Google Scholar, PubMed, ScienceDirect, and Scopus. The inclusion criteria focused on studies that examined V. parahaemolyticus prevalence, virulence factors, and AMR in shrimp from farms to retail outlets. A total of 32 studies were analyzed, revealing a pooled estimate prevalence of V. parahaemolyticus in shrimp at 46.0%, with significant heterogeneity observed. Subgroup analysis highlighted varying prevalence rates across continents, emphasizing the need for further investigation. Virulence factor analysis identified thermostable direct hemolysin (tdh) and tdh-related hemolysin (trh) as the most common. Phenotypic AMR analysis indicated notable resistance to glycopeptides, nitrofurans, and beta-lactams. However, the correlation between antimicrobial usage in shrimp farming and observed resistance patterns was inconclusive. Funnel plots suggested potential publication bias, indicating a need for cautious interpretation of findings. This study underscores the urgency of coordinated efforts to address AMR in V. parahaemolyticus to safeguard public health and to ensure sustainable aquaculture practices.

The cAMP Receptor Protein (CRP) of Vibrio mimicus Regulates Its Bacterial Growth, Type II Secretion System, Flagellum Formation, Adhesion Genes, and Virulence

Vibrio mimicus is a serious pathogen in aquatic animals, resulting in significant economic losses. The cAMP receptor protein (CRP) often acts as a central regulator in highly pathogenic pathogens. V. mimicus SCCF01 is a highly pathogenic strain isolated from yellow catfish; the crp gene deletion strain (Δcrp) was constructed by natural transformation to determine whether this deletion affects the virulence phenotypes. Their potential molecular connections were revealed by qRT-PCR analysis. Our results showed that the absence of the crp gene resulted in bacterial and colony morphological changes alongside decreases in bacterial growth, hemolytic activity, biofilm formation, enzymatic activity, motility, and cell adhesion. A cell cytotoxicity assay and animal experiments confirmed that crp contributes to V. mimicus pathogenicity, as the LD50 of the Δcrp strain was 73.1-fold lower compared to the WT strain. Moreover, qRT-PCR analysis revealed the inhibition of type II secretion system genes, flagellum genes, adhesion genes, and metalloproteinase genes in the deletion strain. This resulted in the virulence phenotype differences described above. Together, these data demonstrate that the crp gene plays a core regulatory role in V. mimicus virulence and pathogenicity.