In this study, we used 16sRNA sequencing to characterize the bacteriota of four trematode species that use the same snail species as intermediate host (Zeacumantus subacarinatus), as well as to characterize the bacteriome of snails infected by these different trematode species (Galactosomum otepotiense, Philophthalmus attenuatus, Acanthoparyphium sp., and Maritrema novazelandense). All parasitised snails were collected at the same time and place (Lower Portobello Bay, Otago Peninsula, New Zealand). Some snails were co-infected by P. attenuatus and M. novazelandense, and the effect of co-infection on the parasites and snails bacteriota was also investigated. Our study goals were to investigate microbial source and sharing among different parasites infecting the same host species, shedding light on the role of microbiomes in parasite-host interactions.