Antimicrobial Agents and Chemotherapy, November 1998, p. 2883-2888, Vol. 42, No. 11
0066-4804/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Division of Infectious Diseases,
Received 9 February 1998/Returned for modification 16 June
1998/Accepted 19 August 1998
A mutant (TX5127) of Enterococcus faecalis OG1RF was
generated by disruption mutagenesis of a previously described autolysin gene. TX5127 formed longer chains (2 to 10 cells per chain) than wild-type OG1RF (mainly single cells) during growth in broth even though it had a growth rate similar to that of the parental strain as
measured by turbidity and cell count. Autolysin activity, as defined by
the ability to lyse heat-killed Micrococcus lysodeikticus cells, was absent in TX5127, while this activity was easily detectable in OG1RF. However, disruption of this autolysin gene did not block the
ability of TX5127 to hydrolyze E. faecalis cell walls
compared to that of OG1RF. The autolysis rate of cells of TX5127 in 10 mM sodium phosphate buffer (pH 6.8) was slower than that of wild-type OG1RF. TX5127 also showed a decreased rate of lysis in the presence of
penicillin, as measured by changes in the turbidity of the culture
during 24 h of incubation at 37°C and a slightly decreased effect of penicillin as measured by time-kill curves. The virulence of
TX5127 was similar to that of OG1RF in the mouse peritonitis model,
indicating that the autolysin of E. faecalis is not
important for infection in this model.
*
Corresponding author. Mailing address: Center for the
Study of Emerging and Re-emerging Pathogens, Division of Infectious Diseases, Department of Medicine, University of Texas Medical School,
6431 Fannin St., Houston, TX 77030. Phone: (713) 500-6767. Fax: (713)
500-5495. E-mail:
iminfdis{at}heart.med.uth.tmc.edu.
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