Application of biofertilizers increases fluoroquinolone resistance in Vibrio parahaemolyticus isolated from aquaculture environments

Distinct increase in antimicrobial resistance genes among Vibrio parahaemolyticus in recent decades worldwide

Vibrio parahaemolyticus is a common pathogen, and has emerged with multiple antimicrobial resistance (AMR). However, few studies have conducted large-scale investigations of AMR and virulence trends of V. parahaemolyticus worldwide. This study longitudinally monitored antibiotic resistance genes (ARGs) and virulence factor genes (VFGs) trends of 1540 V. parahaemolyticus isolates isolated from 1951 to 2021. The number of ARGs in V. parahaemolyticus isolates distinctly increased over the years (P = 5.9e-10), while the number of VFGs decreased significantly (P < 2.2e-16). However, the number of VFGs of isolates isolated from humans has not changed significantly over the years (R = 0.013, P = 0.74), suggesting that the pathogenic risk to humans has not been reduced. Besides, mobile genetic elements are important contributors to ARGs in V. parahaemolyticus (R = 0.34, P < 2.2e-16), but have no promoting effect on VFGs (P = 0.50). The structural equation model illustrated that the human development index promoted the consumption of antibiotics, thereby indirectly promoting an increase in the AMR of the V. parahaemolyticus isolates. Finally, the random forest was performed to predict the ARG and VFG risks of global terrestrial V. parahaemolyticus isolates, and successfully map these threats with over 80% accuracy. This study aimed to evaluate the global risks posed by AMR and virulence, which helps to develop methods specifically targeting V. parahaemolyticus to mitigate these threats.

Transcriptome analysis of Fenneropenaeus merguiensis in response to Vibrio proteolyticus infection

In recent years, due to the destruction of the culture environment and serious ecological pressure, especially in the process of culture, residual bait, faeces and fishery drug abuse will lead to the accumulation of harmful metabolites such as ammonia nitrogen and nitrite, and biological denitrification is the most economical and effective method to remove the single. Therefore, in this study, a nitrite removal strain XA19 was isolated and screened from a shrimp biofloc culture pond. This strain was identified as a clade of Vibrio proteolyticus because the homology between XA19 and V. proteolyticus WDVP was as high as 99.86% by using 16S rDNA gene sequence analysis and NCBI database comparison. Scanning electron microscopy images showed that V. proteolyticus is short-rod-shaped with a curved body and no budding spores, pods and flagella. Antimicrobial susceptibility test proved that V. proteolyticus was resistant to ampicillin, oxacillin, penicillin, vancomycin and clindamycin. In the median lethal concentration 50 (LC50 ) test, at 7-day post-infection (dpi), LC50 of V. proteolyticus for Fenneropenaeus merguiensis was 1.69 × 104  CFU/mL. Transcriptome sequencing analysis was carried out on hepatopancreas of F. merguiensis at 24 and 48 hpi. A total of 176 differentially expressed genes (DEGs) were screened at 24 hpi, including 104 up-regulated DEGs and 72 down-regulated DEGs, and a total of 52 DEGs were screened at 48 hpi, including 32 up-regulated DEGs and 20 down-regulated DEGs. In the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of DEGs, many immune-related signalling pathways were significantly enriched, including Hippo signalling pathway, phagosome, Toll and Imd signalling pathways and Wnt signalling pathway. In addition, some pathways related to Warburg effect were also enriched, including Glycolysis/Gluconeogenesis, Biosynthesis of amino acids, amino sugar and nucleotide sugar metabolism and so on. In this study, the toxicity and drug sensitivity of V. proteolyticus were systematically studied, and the immune response of hepatopancreas of F. merguiensis to V. proteolyticus infection was preliminarily revealed from the molecular level. The results may provide a reference for the prevention and control of V. proteolyticus.

Antibiotic Resistance in the Finfish Aquaculture Industry: A Review

Significant challenges to worldwide sustainable food production continue to arise from environmental change and consistent population growth. In order to meet increasing demand, fish production industries are encouraged to maintain high growth densities and to rely on antibiotic intervention throughout all stages of development. The inappropriate administering of antibiotics over time introduces selective pressure, allowing the survival of resistant bacterial strains through adaptive pathways involving transferable nucleotide sequences (i.e., plasmids). This is one of the essential mechanisms of antibiotic resistance development in food production systems. This review article focuses on the main international regulations and governing the administering of antibiotics in finfish husbandry and summarizes recent data regarding the distribution of bacterial resistance in the finfish aquaculture food production chain. The second part of this review examines promising alternative approaches to finfish production, sustainable farming techniques, and vaccination that circumvents excessive antibiotic use, including new animal welfare measures. Then, we reflect on recent adaptations to increasingly interdisciplinary perspectives in the field and their greater alignment with the One Health initiative.

Pathogenicity and transcriptome analysis of a strain of Vibrio owensii in Fenneropenaeus merguiensis

Vibrio is an important conditional pathogen in shrimp aquaculture. This research reported a dominant bacteria strain E1 isolated from a shrimp tank with the method of biofloc culture, which was further identified as Vibrio owensii. To understand the interaction between V. owensii and the host shrimp, we studied the pathogenicity of the V. owensii and the molecular mechanisms of the Fenneropenaeus merguiensis immunity during the Vibrio invasion. Drug susceptibility tests showed that V. owensii was resistant to antibiotics streptomycin oxacillin, tetracycline, minocycline, and aztreonam, but highly sensitive to cefazolin, cefotaxime, and ciprofloxacin, and moderately sensitive to cefotaxime, ampicillin, and piperacillin. Lethal concentration 50 (LC₅₀) test was performed to evaluate the toxicity of V. owensii to F. merguiensis. The LC₅₀ of V. owensii infected F. merguiensis after 24, 48, 72, 96, 120, 144 and 168 h were 1.21 × 10⁷, 1.68 × 10⁶, 6.36 × 10⁵, 2.15 × 10⁵, 7.58 × 10⁴, 5.55 × 10⁴ and 4.33 × 10⁴ CFU/mL. In order to explore the molecular response mechanism of F. merguiensis infected with V. owensii, the hepatopancreas of F. merguiensis were sequenced at 24 hpi and 48 hpi, and a total 40,181 of unigenes were obtained. Through comparative transcriptomic analysis, 86 differentially expressed genes (DEGs) (including 38 up-regulated DEGs, and 48 down-regulated DEGs) and 305 DEGs (including 150 up-regulated DEGs, and 155 down-regulated DEGs) were identified at 24 hpi and 48 hpi, respectively. Annotation and classification analysis of these 391 DEGs showed that most of the DEGs were annotated to metableolic and immune pathways, which indicated that F. merguiensis responded to the invasion through the regulation of material metableolism and immune system genes during V. owensii infection. In the KEGG enrichment analysis, some pathways related to immune response were significantly influenced by V. owensii infection, including phagosome, MAPK signalling pathway and PI3K-Akt signalling pathway. In addition, some pathways related to the warburg effect were also significantly enriched after V. owensii infection, including pyruvate metableolism, glycolysis/gluconeogenesis, and citrate cycle (TAC cycle). Further analysis showed that C-type lectins and ficolin were also play important roles in the immune response of F. merguiensis against V. owensii infection. The current research preliminarily revealed the immune response of F. merguiensis to V. owensii infection at the molecular level, which provided valuable information to further understand the disease control and the interaction between shrimp and Vibrio.

Distribution of genetic elements associated with antibiotic resistance in treated and untreated animal husbandry waste and wastewater

Animal breeding for meat production based on swine, cattle, poultry, and aquaculture is an activity that generates several impacts on the environment, among them the spread of antibiotic resistance. There is a worldwide concern related to the massive use of antibiotics, which causes selective pressure on the microbial community, triggering bacteria that contain "antibiotic resistance genes." According to the survey here presented, antibiotic resistance-related genes such as tetracyclines (tet), erythromycin (erm), and sulfonamides (sul), as well as the genetic mobile element interferon (int), are the most reported genetic elements in qualitative and quantitative studies of swine, cattle, poultry, and aquaculture manure/wastewater. It has been observed that biological treatments based on waste composting and anaerobic digestion are effective in ARG removal, particularly for tet, bla, erm, and qnr (quinolone) genes. On the other hand, sul and intI genes were more persistent in such treatments. Tertiary treatments, such advanced oxidative processes, are suitable strategies to improve ARG reduction. In general temperature, hydraulic retention time, and penetration of sunlight are the main operational parameters for ARG reduction in treatments applied to animal waste, and therefore attention should be addressed to optimize their efficacy regarding ARG removal. Despite being reduced, the presence of ARG in treated effluents and in biosolids indicates that there is a potential risk of antibiotic resistance spread in nature, especially through the release of treated livestock waste into the environment.

Occurrence of Virulence Factors and Antibiotic and Heavy Metal Resistance in Vibrio parahaemolyticus Isolated from Pacific Mackerel at Markets in Zhejiang, China

ABSTRACT

Vibrio parahaemolyticus is a widespread bacterium in the marine environment and is one of the leading causes of food-derived bacterial poisoning in humans worldwide. The main objective of this study was to determine the prevalence, virulence factors, and antibiotic and heavy metal resistance profiles of V. parahaemolyticus in Pacific mackerel (Pneumatophorus japonicus) from different markets in Zhejiang Province, People's Republic of China. In total, 112 (31.11%) V. parahaemolyticus isolates were identified from 360 Pacific mackerel samples, with an extremely low occurrence of the virulence genes trh (1.79%, 2 of 112) and tdh (0%, 0 of 112). Antibiotic resistance testing revealed that most isolates showed resistance to ampicillin (96.43%, 108 of 112) and streptomycin (90.18%, 101 of 112), whereas all strains were sensitive to kanamycin, florfenicol, cefamandole, and trimethoprim-sulfamethoxazole. Furthermore, 46.43% (52 of 112) of isolates, which had 12 different phenotypes, were classified as multidrug resistant. In addition, the multiple antibiotic resistance index values of isolates were between 0.05 and 0.63, and the maximum multiple antibiotic resistance index was attributed to two isolates that exhibited resistance to 12 antibiotics. Heavy metal resistance patterns were similar among the six different markets. The majority of isolates showed resistance to Cd2+ (78.57%) and Pb2+ (51.79%), and fewer were resistant to Cu2+ (37.50%), Zn2+ (25.00%), Co2+ (9.82%), Ni2+ (6.25%), and Mn2+ (4.46%). No isolates were resistant to Cr3+. In total, 22.32% (25 of 112) of strains were multiheavy metal resistant. Furthermore, multidrug resistance and multiheavy metal resistance were found to be positively correlated in the V. parahaemolyticus strains by using Pearson's correlation analysis (P = 0.008; R = 0.925). This information will contribute to the monitoring of variations in the antibiotic and heavy metal resistance profiles of V. parahaemolyticus strains from seafood and provide insight into the appropriate use of antibiotics and the safe consumption of seafood.

HIGHLIGHTS

Co-occurrence of Antibiotic and Heavy Metal Resistance and Sequence Type Diversity of Vibrio parahaemolyticus Isolated From Penaeus vannamei at Freshwater Farms, Seawater Farms, and Markets in Zhejiang Province, China

Vibrio parahaemolyticus is the leading cause of seafood-borne bacterial poisoning in China and is a threat to human health worldwide. The aim of this study was to assess the antibiotic resistance profiles and distribution of heavy metal resistance of V. parahaemolyticus isolates from Penaeus vannamei from freshwater farms, seawater farms, and their corresponding markets in Zhejiang, China and to assess the relationship between multidrug resistance (MDR) and multi-heavy metal resistance (MHMR). Of the 360 P. vannamei samples that we tested, 90 (25.00%) were V. parahaemolyticus positive, but the occurrence of pathogenic isolates carrying the toxin genes tdh (4.44%) and trh (3.33%) was low. None of the tested isolates harbored both the tdh and trh genes. However, antibiotic resistance profiles varied among different sampling locations, levels of resistance to the antibiotics ampicillin (76.67%) and streptomycin (74.44%) were high overall, and MDR isolates were common (40.00% of all isolates). Heavy metal resistance patterns were similar among the different sampling locations. Overall, the majority of V. parahaemolyticus isolates displayed tolerance to Cd²⁺ (60.00%), and fewer were resistant to Cu²⁺ (40.00%), Zn²⁺ (38.89%), Ni²⁺ (24.44%), Cr³⁺ (14.44%), and Co²⁺ (8.89%). In addition, 34.44% (31/90) of isolates tested in this study were found to be MHMR. Using Pearson's correlation analysis, MDR and MHMR were found to be positively correlated (P = 0.004; R = 0.759). The 18 V. parahaemolyticus isolates that were both MDR and MHMR represented 18 sequence types, of which 12 were novel to the PubMLST database, and displayed a high level of genetic diversity, suggesting that dissemination may be affected by mobile genetic elements via horizontal gene transfer. However, a low percentage of class 1 integrons without gene cassettes and no class 2 or 3 integrons were detected in the 18 MDR and MHMR isolates or in the 90 V. parahaemolyticus isolates overall. Thus, we suggest that future research focus on elucidating the mechanisms that lead to a high prevalence of resistance determinants in V. parahaemolyticus. The results of this study provide data that will support aquatic animal health management and food safety risk assessments in the aquaculture industry.

Attenuation of Vibrio parahaemolyticus Virulence Factors by a Mixture of Natural Antimicrobials

Reducing acute mortality in aquatic crustaceans using natural alternatives to antibiotics has become a necessity, firstly for its positive impact on the aquaculture industry and, secondly, because the extensive use of antibiotics may lead to increased levels of drug resistance in pathogenic microorganisms. This study aimed to investigate the effect of a mixture of natural antimicrobials on the in vitro and in vivo virulence abilities of Type VI secretion system (T6SS)-positive Vibrio parahaemolyticus (A3 and D4), strains known as having potentially harmful health consequences for aquatic crustaceans and consumers. Herein, we report that a natural antimicrobial mixture (A3009) was capable of significantly reducing the virulence of V. parahaemolyticus strains A3 and D4 in an in vitro infection model, using the fish cell line CHSE-214, an effect which correlates with the bacterial downregulation of hcp1 and hcp2 gene expression and with the ability of the antimicrobial to efficiently retain low cytotoxic levels (p < 0.001). We show for the first time that a natural antimicrobial is able to significantly reduce the mortality of shrimps in a challenge experiment and is able to significantly attenuate H₂O₂ release during infection (p < 0.001), indicating that it could harbor positive intestinal redox balance effects.