The plasmid profiles of six isolates of Staphylococcus epidermidis were repetitively evaluated over an 8-month period. Each isolate was subcultured and stored at three different temperatures (-70 degrees C, -20 degrees C, and room temperature) and plasmid DNA was prepared from each subculture at 0, 1, 4, and 8 months by two different methods of plasmid extraction [using mixed alkyltrimethylammonium bromide (ATAB) or Brij 58 and deoxycholate (modified Parisi)]. Plasmid DNA bands were lost from two isolates when subcultures were kept at room temperature. This plasmid loss was confirmed by repetitive extractions and electrophoresis, as well as by restriction endonuclease analysis of the ATAB preparations. Profiles were otherwise highly related to one another, with occasional exceptions being extra or missing plasmid DNA bands of high molecular size. The latter findings were not reproducible. Plasmid DNA extracted by the modified Parisi method was not reliably digested with restriction endonuclease enzymes. We conclude that the plasmid profiles of Staphylococcus epidermidis isolates are highly reproducible as long as isolates are stored at less than or equal to -20 degrees C. Minor discrepancies in the number of plasmid DNA bands of large molecular size may occur. These are resolvable by repetitive testing or restriction endonuclease analysis of ATAB-extracted plasmid DNA preparations.

Cold Temperature↗

PubMedDate not supplied

The diagnosis of streptococcal pharyngitis by the antibody-coated bacteria test.

Fluorescein isothiocyanate-labelled goat antihuman immunoglobulin (anti-IgG, anti-IgA, anti-IgM) and anticomplement conjugates were used to detect antibody or complement-coated bacteria from the oropharynx of patients with pharyngitis. Throat smears prepared from patients with a positive culture for group A beta-hemolytic streptococci had significantly more bacteria that stained with labelled antihuman IgG than smears prepared from patients with a negative culture. When compared to the results of a throat culture, the sensitivity, specificity, and predictive value of a positive and negative antihuman IgG stained smear was 91 percent, 94 percent, 85 percent, and 96 percent, respectively. The results of smears stained with antihuman IgA, IgM or complement did not correlate statistically with the isolation of group A beta-hemolytic streptococci.

Animals↗