Vibrio is the most common bacterium associated with diseases in crustaceans. Outbreaks of vibriosis pose a serious threat to shrimp production. Therefore, antibiotics are commonly used as preventative and therapeutic measures. Unfortunately, improper use of antibiotics leads to antibiotic resistance. Nevertheless, information on the occurrence of Vibrio spp. and antibiotic use in shrimp, particularly in Malaysia, is minimal. This study aimed to provide information on the occurrence of Vibrio spp., its status of antibiotic resistance and the plasmid profiles of Vibrio spp. isolated from cultured shrimp in Peninsular Malaysia. Shrimp were sampled from seven farms that were located in different geographical regions of Peninsular Malaysia. According to the observations, 85% of the shrimp were healthy, whereas 15% were unhealthy. Subsequently, 225 presumptive Vibrio isolates were subjected to biochemical tests and molecular detection using the pyrH gene. The isolates were also tested for antibiotic susceptibility against 16 antibiotics and were subjected to plasmid profiling. Eventually, 13 different Vibrio spp. were successfully isolated and characterized using the pyrH gene. They were the following: V. parahaemolyticus (55%), V. communis (9%), V. campbellii (8%), V. owensii (7%), V. rotiferianus (5%), Vibrio spp. (4%), V. alginolyticus (3%), V. brasiliensis (2%), V. natriegens (2%), V. xuii (1%), V. harveyi (1%), V. hepatarius (0.4%) and P. damselae (3%). Antibiotic susceptibility profiles revealed that all isolates were resistant to penicillin G (100%), but susceptible to norfloxacin (96%). Furthermore, 16% of the isolates revealed MAR of less than 0.2, while 84% were greater than 0.2. A total of 125 isolates harbored plasmids with molecular weights between 1.0 and above 10 kb, detected among the resistant isolates. The resistant isolates were mediated by both chromosomal and plasmid factors. These findings support the use of surveillance data on the emerging patterns of antimicrobial-resistance and plasmid profiles of Vibrio spp. in shrimp farms. The findings from this study can be used to develop a better disease management strategy for shrimp farming.

Shrimp is a commercially important species in several regions and is among the key global aquaculture commodities essential for food production and security. Similar to most shrimp‐producing countries, shrimp aquaculture in Malaysia suffers from recurring disease outbreaks that consequently impact the overall economy. The use of antimicrobial agents, particularly antibiotics, in shrimp aquaculture for prophylactic treatment and growth enhancement has increased the spread of antimicrobial‐resistant bacteria in the aquatic environment. The development and dissemination of antimicrobial‐resistant bacteria and other potential sources of antimicrobial contamination in waterways are facilitated by the continuous application of antibiotics in shrimp farming, municipalities, livestock, hospitals and pharmaceutical sources. This situation contributes to the spread of the antimicrobial resistance (AMR) phenomenon, a One Health issue with detrimental effects on human and animal health as well as the environment. Addressing the risks associated with AMR dissemination remains highly challenging due to the intensification of shrimp farming trends, which heightens disease outbreaks, and the limited availability of alternatives to antibiotics for many farmers seeking to prevent crop failure. In this review, we critically examine the key issues related to AMR in shrimp aquaculture and explore emerging treatment strategies. Our analysis encompasses a comprehensive review of the existing literature on the impact of AMR on shrimp farming in Malaysia, as well as alternative mitigation strategies aimed at fostering more sustainable and resilient aquaculture practices.

Nowadays, bacterial diseases caused by Vibrio spp. pose a significant obstacle to aquaculture growth, affecting socioeconomic development. The presence of pathogenic Vibrio spp. are gaining attention due to widespread mortality in fish and shellfish worldwide. This study investigates the distribution of virulence genes and their pathogenicity by experimentally infecting a healthy group of cultured shrimp, specifically Penaeus monodon. A total of 225 Vibrio spp. isolated from 210 cultured shrimp from various geographical regions in Peninsular Malaysia were examined, resulting in 13 Vibrio spp. being identified and characterized. According to virulence gene assessment, only eight of the 11 virulence genes were detected in the isolates, including chiA (89), flaC (74), tlh (72), toxR (70), luxR (40), pirA (11), pirB (11), and hlyA (0.4). Other virulence genes, such as tdh, trh, and ctxA, were not found in any of the isolates (0). Then, three Vibrio isolates, including V. parahaemolyticus S12-3, V. campbellii S10-4, and V. rotiferianus S24-4, were selected for pathogenicity test based on highest number of virulence genes in each species. These species were subjected to immersion challenge test against postlarvae (PL) P. monodon approximately PL-20 with three different concentrations of 110⁶, 110⁷, and 110⁸CFU/mL. The V. parahaemolyticus S12-3 was determined to have lethal concentration 50 (LC₅₀) 110⁵CFU/mL after 168hr of exposure. The immersion challenge test resulted in a pale hepatopancreas and empty guts in P. monodon. Histopathological examination showed sloughing of epithelial cells in the hepatopancreatic tubule, hemocytic infiltration, massive vacuolation, and loss of hepatopancreatic tubule structure. Overall, the study demonstrated the virulence and pathogenicity of V. parahaemolyticus S12-3 toward P. monodon, which could be associated with its virulence properties. Furthermore, the current findings will be useful in developing microbiological risk assessments for shrimp farming and aquaculture management.

Vibriosis causes a major setback in the marine aquaculture industry. In controlling vibriosis, vaccination of the broodstock could help in transferring the initial immunity to the fry and perhaps giving immunity to them during the culture period. This study determines the efficacy of three live-attenuated Vibrio harveyi vaccine (LAVh) derivatives on zebrafish broodstock in providing immunological protection to their offspring against pathogenic Vibrio spp. Zebrafish were vaccinated intraperitoneally with full effective dose (ED₈₀) and monitored for 14weeks. On week 6, the specimens were intraperitoneally (i.p.) challenged with pathogenic 10⁷CFU/ml of Vibrio spp., and subsequently another batch was left to spawn. Thereafter, the antibody level of larvae was monitored for 4weeks post-hatching. Groups of juvenile zebrafish were given booster vaccination via immersion (1×10⁷CFU/mL) with vaccines similar to their predecessor. The fish were sampled weekly for four weeks to determine their antibody profile and pro-inflammatory gene expression. Finally, at week 3, the juvenile fish were challenged with pathogenic strains of Vibrio spp. Results of antibody profiling in the adult zebrafish model indicated that freeze-dried and stale LAVh delivers a longer immunological protective duration, while the FKVh vaccination group failed to provide immunological protection against V. alginolyticus. However, the gene expression of pro-inflammatory interleukin 1β (IL-1β) in the FKVh vaccinated group was elevated longer than that in the freeze-dried LAVh vaccinated group. Nevertheless, the relative percent survival (RPS) of both vaccination groups against pathogenic Vibrio spp. displayed 100 immunity. Overall, the freeze-dried LAVh vaccine was found to confer maternal immune protection for its offspring, provide a long duration of immunological protection and cross-protection coverage against pathogenic Vibrio spp., and have a longer shelf life. It is proposed to be commercially available for farmers to protect against Vibrio spp. infection.