Inoculation Route and Serotype Alter Salmonella Recovery in the Broiler's Digestive Tract.

Salmonella enterica serotypes Enteritidis (SE) and Heidelberg (SH) are consistently linked to poultry-related foodborne outbreaks and can be isolated from broiler parts in processing facilities. In order to control this pathogen's establishment in the broiler, entryways at the farm that lead to colonization must be considered. The objective of these trials was to determine if the inoculation route of either SE or SH altered its recovery in a market-age broiler's digestive tract if chicks were dosed on day of hatch. Chicks were given a 104 colony-forming units inoculation of SE or SH on day 0 via one of five inoculation routes (oral, intratracheal, subcutaneous, ocular, or cloacal) and then placed in pens (60-100 chicks/treatment). Broilers were reared for 32-36 days, then euthanatized, and samples of trachea, crop, liver and spleen (pooled), cecum, and a cloacal swab were collected. Samples were enriched and then analyzed on yes/no criteria based on Salmonella growth. Data were analyzed in JMP Pro 14.1 using the GLM procedure with the Student t-test to separate serotype means and a Tukey honestly significant difference test to separate inoculation means (P ≤ 0.05). All samples collected and all inoculation routes resulted in recovery of either serotype. The intratracheal inoculation, mimicking inhaled fomites, resulted in significantly higher recovery of Salmonella serotypes than did the other inoculation routes (P < 0.0001), indicating the importance of controlling respiratory contamination. When comparing serotypes, there was a significantly greater recovery of SH compared to SE based on samples collected (P = 0.001). SH also had significantly greater recovery from the cecum (P < 0.001) and the cloacal swab (P = 0.02). These trials indicate the need for further investigation of the intratracheal route, as well as reinforcing that the potential of systemic infection through grow out with either serotype is highly probable preharvest.

Histomonas meleagridis isolates compared by virulence and gene expression.

Pathology and putative virulence factor expression of three Histomonas meleagridis isolates differing in geographic origin, cell passage number (56 or 100), or cell populations grown from a monoculture were compared. Turkey poults inoculated with the high cell passage number isolates or monoculture isolates varied in gross lesion severity and weight gain (P<0.0001). Screening of a published H. meleagridis cDNA library identified forty- eight cysteine proteinases (CP) and one superoxide dismutase (Fe-SOD) proposed to function in either tissue damage and/or invasion and oxidative defense. The Fe-SOD and eight CPs were analyzed using real time polymerase chain reaction. CP2, CP3, and CP8 showed significant differences in expression among the field isolates (P ≤ 0.05). The high passage isolates had decreased CP2, CP3 and CP4 expression when compared with their field isolate. CP7 did not differ between field isolates or the 56-passaged isolate. The Fe-SOD gene showed significant differences in expression among the various isolates. When exposing cultured H. meleagridis to air, Fe-SOD expression decreased rapidly during the first hour of air exposure but increased progressively through the next 3 h. This study provides information on gross pathology and virulence factors associated with various isolates of Histomonas meleagridis which can aid in determining the pathogenetic mechanisms used by this organism.