Generating super-shedders: co-infection increases bacterial load and egg production of a gastrointestinal helminth

Lass, Sandra; Hudson, Peter J.; Thakar, Juilee; Saric, Jasmina; Harvill, Eric; Albert, Réka; Perkins, Sarah E.

The efficiency of the reporter bacteria was assessed first, and it was determined that light output (RLUs) from selfbioluminescent bacteria measured in vivo was positively correlated (r ¼ 0.82; p , 0.05) with the CFUs of bacteria from animals that were sacrificed at days 3, 6, 12 and 24 (figure 1). Bacteria were observed in the lungs in some co-infected animals as early as day 2, progressing to the trachea of both single and co-infected animals from day 5 after which a persistent nasal infection occurred in both treatment groups (figures 2 and 3). If bacterial infection reached higher than the average bacterial load by 2 s.d.s (as measured by RLUs), these individuals were assessed to have reached one of the ethical endpoints of the experiment (systemic infection) and according to the guidelines of the IACUC were euthanized (e.g. co-infected individual in position 3 on day 5; figure 3 ). Taking account of the variance associated with individuals, significantly higher bacterial loads were found in the lungs of co-infected animals compared with single-infected animals (GLMM: F 2,28 ¼ 4.22; p ¼ 0.03). There was no significant difference between the mean whole body bacterial load of single and co-infected animals rsif.royalsocietypublishing.org J R Soc Interface 10: 20120588 (GLMM: F 2,28 ¼ 2.50; p ¼ 0.11) and in the mean bacterial load in the nose and trachea between co-infected and singleinfected animals (GLMM: F 2,28 ¼ 1.14; p ¼ 0.35).