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Infect. Immun., Apr 1997, 1550-1556, Vol 65, No. 4
MC Booth, AL Cheung, KL Hatter, BD Jett, MC Callegan and MS Gilmore
Previous studies showed that an agr mutant strain of Staphylococcus aureus
was partially attenuated in virulence compared to a parental strain in
experimental endophthalmitis. The purpose of this study was to determine
whether the sar locus, either alone or through interactions with agr,
contributes to the regulation of virulence in S. aureus endophthalmitis.
Experimental endophthalmitis was established by the midvitreous injection
of approximately 30 CFU of S. aureus RN6390 or the isogenic attenuated
strains RN6911 (agr mutant), ALC136 (sar mutant), and ALC135 (agr sar
double mutant). Unexpectedly, the rate of reduction in electroretinographic
B-wave amplitude in eyes infected with strain ALC136 (sar mutant) was not
significantly different from the parental strain on postinfection day (PID)
5 (10% retention). In contrast, ALC135 (agr sar double mutant)-infected
eyes retained 73% of preoperative B-wave amplitude on PID 5. Therefore,
unlike agr, a mutation in the sar locus alone does not alter the overall
virulence of wild-type S. aureus in experimental endophthalmitis. However,
the combined effect of insertional mutations in both the sar and agr global
regulators leads to near-complete attenuation of virulence.
Copyright © 1997, American Society for Microbiology
Staphylococcal accessory regulator (sar) in conjunction with agr contributes to Staphylococcus aureus virulence in endophthalmitis
Department of Ophthalmology and Dean A. McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City 73190, USA. mary- booth@uokhsc.edu
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