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K L Hatter

Publications and source records attributed to K L Hatter.

4 recordsLinked to original sources
PubMed1998

Molecular epidemiology of Staphylococcus aureus and Enterococcus faecalis in endophthalmitis.

Genomic DNA fingerprint analysis was performed on 39 Staphylococcus aureus and 28 Enterococcus faecalis endophthalmitis isolates collected from multiple clinical centers. Among 21 S. aureus genomic DNA fingerprint patterns identified, five clonotypes were recovered from multiple unrelated patients and accounted for 58.9% (23 of 39) of the isolates analyzed. Compared with strains having unique genomic DNA fingerprint patterns, the S. aureus clonotypes occurring more than once were more likely to result in visual acuities of 20/200 or worse (P = 0.036 [chi2 test]). In contrast to the S. aureus isolates, the E. faecalis endophthalmitis isolates were a clonally diverse population, enriched for the expression of a known toxin, cytolysin, which is plasmid encoded.

Bacterial Typing Techniques↗
PubMed1997

Staphylococcal accessory regulator (sar) in conjunction with agr contributes to Staphylococcus aureus virulence in endophthalmitis.

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.

Bacterial Proteins↗
PubMed1996

Structural analysis and proteolytic activation of Enterococcus faecalis cytolysin, a novel lantibiotic.

Clinical isolates of Enterococcus faecalis more commonly produce a cytolysin than do commensal isolates. Epidemiologic evidence and animal-model studies have established a role for the cytolysin in the pathogenesis of enterococcal disease. The cytolysin consists of two structural subunits, CylLL and CylLS, that are activated by a third component, CylA. Genetic and biochemical characterization of CylA indicate that it is a serine protease, and that activation putatively results from cleavage of one or both cytolysin subunits. Genetic evidence also suggests that the cytolysin subunits are related to the rapidly growing class of bacteriocins termed lantibiotics. However, unlike lantibiotics, the cytolysin is lytic for eukaryotic as well as prokaryotic cells, and it consists of two structural subunits. This report describes the purification and characterization of the cytolysin subunits and detection of lanthionine-type post-translational modifications within their structures. Furthermore, the cleavage specificity of the CylA activator is reported and it is shown that proteolytic activation of both subunits is essential for activity.

Amino Acid Sequence↗