Characterization of heterogeneous vancomycin-intermediate resistance, MIC and accessory gene regulator (agr) dysfunction among clinical bloodstream isolates of staphyloccocus aureus

Table 1 Summary of the prevalence of MRSA and hVISA in 220 S.aureus bloodstream isolates

	*S. aureus* 220	MSSA 55% (121/220)	MRSA 45% (99/220)	hVISA 5.5% (12/220)
MIC50/90	1/2	1/2 (p = 0.51)^a	1/2 (p = 0.46)^a	1.5/2 (p = 0.03)^a
agr-dysfunction	15% (33/220)	10% (12/121)	21% (21/99) (p = 0.02)^b	58% (7/12) (p< 0.0005)^c

MIC_50/90 determined by CLSI broth microdilution and the prevalence of agr-dysfunctional
^a MIC distribution of total clinical S.aureus versus MIC distribution of each phenotype (Mann-Whitney U)
^b Prevalence of agr dysfunction in MRSA isolates versus MSSA isolates (Chi-square test)
^c Prevalence of agr dysfunction in hVISA isolates versus VSSA isolates (Chi-square test)

ISSN: 1471-2334