The importance of agr and aryK in the virulence of ST93 CA-MRSA. Isogenic repaired agr mutant TPS3105r compared to TPS3105 and JKD6159, and JKD6159 compared with isogenic repaired AraC/XylS family regulator mutant (JKD6159_AraCr) in a BALB/c mouse skin infection assay. At least 10 mice were used for each bacterial strain. (A) Weight loss induced by intradermal infection with S. aureus strains is demonstrated as percentage loss of weight over 5 days. There was no difference between JKD6159 and TPS3105r in all outcome measures. TPS3105r infected mice had significantly increased weight loss compared to TPS3105 (p < 0.0001). There was a small increase in weight loss in mice infected with JKD6159_AraCr compared to JKD6159 (p = 0.0311). Data shown are mean weight loss and SEM. (B) Skin lesion area (mm2) at 5 days after infection in TPS3105r infected mice was significantly increased compared to TPS3105 (p < 0.0001). Mice infected with JKD6159_AraCr had increased lesion area compared with JKD6159 (p < 0.0001). Data shown are mean area and SEM. (C) Recovery of S. aureus (log CFU) from infected tissues at 5 days after infection from TPS3105r was significantly greater than from TPS 3105 infected mice (p < 0.0001). There was no difference in S. aureus recovered from mice infected with JKD6159 and JKD6159_AraCr. Data shown are mean CFU and SEM. Note, *** p < 0.001, * p < 0.05.
Chua et al. BMC Microbiology 2014 14:31 doi:10.1186/1471-2180-14-31