Enterocytozoon hepatopenaei (EHP) is a specialized intracellular parasitic pathogen that was discovered in the shrimp farming industry in recent years (Thitamadee et al., 2016). In 2003, Monodon slow growth syndrome (MSGS) appeared in Penaeus monodon farmed in Thailand. When investigating the cause, baculovirus, hepatopancreatic parvovirus or unidentified microsporidia was found in the hepatopancreatic cells of the shrimp. Unidentified inclusion bodies of Microsporidium were successfully isolated in 2009 and were defined as a new species of Sporozoites, Shrimp Hepatica (Salachan et al., 2016). The main economically farmed shrimp, such as Litopenaeus vannamei, Palaemon carincauda and Penaeus monodon, are the main targets of infection of Enterocytozoon hepatopenaei. Since its discovery, EHP has been reported in many countries, such as China, Vietnam, Malaysia, Indonesia and Australia (Tang et al., 2016).After infection, the growth of shrimp will be slow or will stagnate, which will affect global shrimp farming production (Karthikeyan and

The aquaculture environment, especially the culture ponds and aquaculture products, is considered to be an important reservoir of colistin resistance genes. However, systematic investigations of colistin resistance in Penaeus vannamei farming in different culture modes are scarce. In this study, a total of 93 non-duplicated samples were collected from P. vannamei farms in five cities in China from 2019 to 2021. The prevalence, antibiotic resistance and multilocus sequence typing (MLST) of colistin-resistant bacteria were measured and analysed. The results showed that among the 1601 isolates in P. vannamei and its environmental samples, the pollution of colistin-resistant bacteria was serious (the overall prevalence was 37.3% and 28.8%, respectively), regardless of the earthen pond or high-density polyethylene (HDPE) film-lined pond. Among 533 isolates, the prevalence of mobile colistin resistance (mcr) genes, mcr-1, was the highest (60%, 320/533), followed by mcr-4 (1.5%, 8/533), mcr-8 (0.9%, 5/533), mcr-10