FIG 5.

Active or passive immunization with SasX reduces nasal colonization caused by MRSA ST239 in a nasal colonization model. (A) Passive immunization. Mice received a total of 10 mg IgG of either rabbit preimmune serum or polyclonal anti-SasX IgG in 24-h intervals via intraperitoneal injection 24 h before (preventive effect) or after (treatment effect) nasal colonization with 10⁷ CFU of MRSA strain HS770. At 7 days after inoculation, all mice were euthanized and evaluated for nasal carriage of S. aureus. Numbers are total CFU per nose. *, P < 0.05. (B) Active immunization. Mice were challenged by introducing 10⁷ live bacterial cells of MRSA strain HS770 into the nares 1 week after the first boosting with rSasX (or the PBS control). Three days and 7 days after inoculation, 12 mice per group were euthanized and evaluated for nasal carriage of S. aureus. Numbers are total CFU per nose. *, P < 0.05; **, P < 0.01.