title: Replicate plating: does it increase reliability?
abstract: As a part of a clinical study to evaluate the antibacterial effect of a topically applied erythromycin gel, microbiological specimens were taken from two groups of patients: one group using 2% erythromycin gel and the other group using a placebo gel. These specimens were plated in triplicate using a common source on bacteriological media using standard procedures. After the appropriate incubation times, the numbers of aerobic and anaerobic organisms were counted separately from each of three plates. A comparison of the bacterial colony counts from the replicate plates showed a high degree of similarity for each type of organism. Tests for treatment differences in organism counts were performed based on single, double and triplicate plating. The results obtained were almost identical, suggesting that replicate plating from a common source is no more accurate than single plating. The only apparent advantage of this type of replicate plating is heightened confidence in the reliability of bacterial counts from single plates.
authors.affiliation: Clinical Research and Biometrics Department, Procter & Gamble Company, Cincinnati, OH, USA.
authors.forename: K K
authors.initials: KK
authors.lastname: Wille
authors.forename: B R
authors.initials: BR
authors.lastname: Vowels
authors.forename: A N
authors.initials: AN
authors.lastname: Foglia
authors.forename: C A
authors.initials: CA
authors.lastname: Berge
authors.forename: B M
authors.initials: BM
authors.lastname: Schnell
authors.forename: F W
authors.initials: FW
authors.lastname: Briese
mesh_terms: D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D001424:Bacterial Infections / Q000188:drug therapy*; D001431:Bacteriological Techniques; D015169:Colony Count, Microbial / Q000379:methods*; D004917:Erythromycin / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D017192:Skin Diseases, Bacterial / Q000188:drug therapy*; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000382:microbiology; D013211:Staphylococcus aureus / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D004917:Erythromycin