85% NaCl (150 μl) in microfuge tubes. Tubes were thoroughly vortexed, and the supernatant was diluted as needed and plated on agar containing 5% sheep blood. Staphylococcus colonies were identified based on morphology, biochemical tests and also analyzed using the HiStaph™ Identification kit (HiMedia). An S. aureus-specific enzyme-linked immunosorbent Lazertinib concentration assay (ELISA) was used for confirmation. Experimental colonization of rat nares and evaluation of P128 efficacy MRSA USA300 was grown overnight on nutrient agar containing 5% sheep blood.
Colonies were harvested by flooding the plate with sterile 0.85% NaCl. Cells were pelleted by centrifugation (5800 × g, 10 min) and resuspended in sterile 0.85% NaCl (2 × 108-5 × 108 cells/μl) for nasal instillation. Rats were grouped and anaesthetized by intraperitoneal injection of ketamine (90 mg/kg body weight) and NCT-501 price xylazine (9 mg/kg body weight). A 10-μl aliquot of S. aureus cell suspension was instilled into the nares of all animals on day 1. After 24 h, twice daily intranasal treatments to anaesthetized rats were initiated according to treatment group: P128 formulated as a hydrogel (50 mg/dose containing 100 μg P128), placebo gel that contained phosphate buffered saline in place of the protein, or Bactroban Nasal (30 mg/dose, 2%
mupirocin ointment, GlaxoSmithKline). On day 3, the rats were euthanized by anesthetic overdose. The nasal tissue (except for the skin around the nares) was removed and processed for quantitative evaluation of colonization as described previously [33, 34]. Aliquots of
the supernatant (diluted as needed) were plated on nutrient agar containing 5% sheep blood and Ilomastat clinical trial incubated overnight at 37°C. The S. aureus USA300 colonies were enumerated by tentative identification of hemolytic phenotype. Representative colonies from each USA300-positive animal were then purified on LB agar for biochemical characterization and confirmation by ELISA. Confirmation of S. aureus by ELISA Purified colonies were suspended in 0.05 M carbonate-bicarbonate buffer (pH 9.6) to a cell density of about 1 × 109 cells/mL. A 200-μL aliquot of this cell suspension was used to coat 96-well plates and incubated overnight before at 4°C. The wells were washed with Tris buffered saline with 0.1% Tween20 (TBST) and blocked with 1% bovine serum albumin (200 μL) in TBST for 1 h at 37°C. After repeated washes with TBST, rabbit polyclonal anti-RN4220 antiserum (100 μL, 1:20000) was added, and plates were incubated for 1 h at 37°C. The wells were washed again with TBST before adding alkaline phosphatase-labeled goat anti-rabbit antibody (100 μl, 1:5000). Plates were incubated for 1 h at 37°C. After washing the wells, the substrate p-nitro phenyl phosphate (100 μL) was added, the plates were incubated for 40 min, and absorbance at 405 nm was determined. Results Identification of TAME of phage K Our bioinformatics analysis indicated that phageK harbors two genes involved in host cell wall lysis.