Paramecium caudatum enhances transmission and infectivity of Mycobacterium marinum and M. chelonae in zebrafish Danio rerio

Abstract

Mycobacterial infections in laboratory zebrafish (Danio rerio) are common and widespread in research colonies. Mycobacteria within free living amoebae have been shown to be transmission vectors for mycobacteriosis. Paramecium caudatum are commonly used as a first food for zebrafish, and we investigated this ciliate’s potential to serve as a vector of Mycobacterium marinum and M. chelonae. The ability of live P. caudatum to transmit these mycobacteria to larval, juvenile and adult zebrafish was evaluated. Infections were defined by histologic observation of granulomas containing acid-fast bacteria in extraintestinal locations. In both experiments, fish fed paramecia containing mycobacteria became infected at a higher incidence than controls. Larvae (exposed at 4 days post hatch) fed paramecia with M. marinum exhibited an incidence of 30% (24/80) and juveniles (exposed at 21 days post hatch) showed 31% incidence (14/45). Adult fish fed a gelatin food matrix containing mycobacteria within paramecia or mycobacteria alone for 2 wk resulted in infections when examined 8 wk after exposure as follows: M. marinum OSU 214 47% (21/45), M. marinum CH 47% (9/19), M. chelonae 38% (5/13). In contrast, fish feed mycobacteria alone in this diet did not become infected, except for 2 fish (5%) in the M. marinum OSU 214 low dose group. These results demonstrate that Paramecium caudatum can act as a vector for mycobacteria. This provides a useful animal model for evaluation of natural mycobacterial infections and demonstrates the possibility of mycobacterial transmission in zebrafish facilities via contaminated paramecia cultures.

The composition of the zebrafish intestinal microbial community varies across development

“…age class, which had begun feeding on Paramecium, were distinguished by the consistent presence of the genus Mycobacterium. Notably, this genus contains the fish pathogens M. marinum and M. chelonae, which were known to be present in our facility during the time of the experiment, and which have recently been shown to be efficiently transmitted to zebrafish via ingestion of infected paramecia (Peterson et al, 2013). Although our sequences did not allow us to resolve the species-level identification of these Mycobacterium OTUs, we detected Mycobacterium sequences in every environmental sample associated with Paramecium feeding (eight samples, average 4% abundance), including all three replicates of the Paramecium food samples, suggesting a possible transmission route (Supplementary Dataset 1).…”

Animal Models of Tuberculosis: Zebrafish

“…Furthermore, transmission was significantly enhanced when the bacteria were supplied within free-living unicellular eukaryotes, including amoeba and paramecium (Harriff et al 2007;Peterson et al 2013). However, these more natural routes of transmission are not really applicable for infection experiments, as the infection dose and timing cannot be easily controlled.…”

A method for Rearing Perch, Perca fluviatilis, Larvae Using Paramecium caudatum, Followed by Wild Zooplankton and Formulated Dry Feed in Combination With Adequate Tank Systems

“…As Paramecium caudatum survives in the fish tanks for unlimited time periods no cleaning and manipulation procedures are necessary (Andrews, 2013). As a disadvantage also bacteria may be introduced into the fish tanks together with the culture medium (Peterson, Ferguson, Watral, Mutoji, Ennis, & Kent, 2013) and the culture water is inadequate for fish larvae in aspects of O 2 and NH 4 concentrations. Therefore, accurate monitoring of tank water quality is necessary when using Paramecium caudatum as larvae feed.…”