| Thin Agar Layer (TAL) medium was developed at Kansas State University to improve resuscitation of injured cells, and has been shown to result in higher recovery than selective media alone for cold, heat, salt, or acid injured cells. This project was designed to determine the effectiveness of the TAL method for the recovery of organisms which may be injured in air from dairy cattle, swine, and poultry confinement facilities; and identify the resulting organisms. Eleven agar media were used throughout the experiment: Tryptic Soy agar (TSA), MacConkey Sorbitol agar (MSA), TAL-MSA, Baird-Parker agar (BP), TAL-BP, Modified Oxford agar (MOX), TAL-MOX, Xylose Lysine Sodium Desoxycholate agar (XLD), TAL-XLD, Yersinia Selective agar (CIN), and TAL-CIN. The TAL plates were prepared by pipetting 6 ml of a selective agar into a BBL Rodac(TM) plate (65 mm x 15 mm). Selective agar was allowed to solidify, then each plate was overlaid with 6 ml of TSA. Selective agar plates were prepared by pipetting 12 ml of agar into BBL Rodac(TM) plates for solidification. Samples were taken at indoor dairy cattle, swine finishing unit, and poultry facilities in 5 separate locations using a BioScience SAS air sampler. Depending on the confinement unit, 10 to 60 L of air was sampled. Three replications of the experiment were performed for all facilities. In nearly all comparisons the TAL method resulted in higher counts of microorganisms on all media tested. In addition, a minimum of 150 isolates were selected from each unit and identified to test selectivity of TAL and selective media for target organisms. The data from all three experiments has shown that the TAL resuscitation method is an effective and necessary procedure for the recovery of injured organisms in air. 83 species were identified during this project; showing that air in confinement facilities is a real source of contaminants. |
