Biomedical subjects

John E Warner

Publications and source records attributed to John E Warner.

3 recordsLinked to original sources

PubMed2004

Diversity of toxic shock syndrome toxin 1-positive Staphylococcus aureus isolates.

Staphylococcus aureus isolates from women with nasal, anal, or vaginal colonization were evaluated for population diversity by pulsed-field gel electrophoresis. Cluster analysis of restriction patterns revealed diversity indices of 0.89 and 0.99 for toxic shock syndrome toxin 1-positive and -negative isolates, respectively. Toxin-producing strains were isolated more frequently from the nares than from other sites.

Anal Canal↗

PubMed2004

Detection of multiple macrolide- and lincosamide-resistant strains of Streptococcus pyogenes from patients in the Boston area.

Macrolide (including erythromycin and azithromycin) and lincosamide (including clindamycin) antibiotics are recommended for treatment of penicillin-allergic patients with Streptococcus pyogenes pharyngitis. Resistance to erythromycin in S. pyogenes can be as high as 48% in specific populations in the United States. Macrolide and lincosamide resistance in S. pyogenes is mediated by several different genes. Expression of the erm(A) or erm(B) genes causes resistance to erythromycin and inducible or constitutive resistance to clindamycin, respectively, whereas expression of the mef(A) gene leads to resistance to erythromycin but not clindamycin. We studied the resistance of S. pyogenes to erythromycin and clindamycin at an urban tertiary-care hospital. Of 196 sequential isolates from throat cultures, 15 (7.7%) were resistant to erythromycin. Three of these were also constitutively resistant to clindamycin and had the erm(B) gene. Five of the erythromycin-resistant isolates were resistant to clindamycin upon induction with erythromycin and had the erm(A) gene. The remaining seven erythromycin-resistant isolates were susceptible to clindamycin even upon induction with erythromycin and had the mef(A) gene. Pulsed-field gel electrophoresis analysis and emm typing demonstrated that the erythromycin-resistant S. pyogenes comprised multiple strains. These results demonstrate that multiple mechanisms of resistance to macrolide and lincosamide antibiotics are present in S. pyogenes strains in the United States.

Anti-Bacterial Agents↗

PubMed2003

Method for optimizing pulsed-field gel electrophoresis banding pattern data.

The genomic DNA of 47 strains of TSST-1 toxin-producing Staphylococcus aureus were cleaved with SmaI restriction endonuclease and resolved in an agarose gel by pulsed-field gel electrophoresis (PFGE). An algorithm was designed to standardize the band weights or brightness (trace quantity) produced to a bounded region between 0 and 1 regardless of DNA fragment size while simultaneously reducing gel-to-gel variability. The algorithm allows for classification of isolates by band intensity as well as DNA mobility without a numerical hierarchy of band intensity that is caused by ranging DNA fragment lengths. On analysis many isolates were classified as separate entities on the basis of DNA co-migration only. Isolates differing by only DNA co-migration were subjected to a second digestion with restriction enzyme SacII. These isolates were characterized similarly to the standardized trace quantity analysis of SmaI PFGE patterns. The standardization method proposed in this article permits characterization of isolates on the basis of band differences, regardless of DNA co-migration, thus increasing the discriminatory power (0.79 to 0.89) of PFGE by increasing band-associated information. An established unbiased approach to the partitioning of data were also explored.

Algorithms↗