Comparison of chairside microbiological screening systems and conventional selective media in children with and without visible dental caries.

PURPOSE: The purpose of this study was to compare the results of commercial chairside microbial tests (CT) and conventional selective media (GS, gold standards) for mutans streptococci (MS) and lactobacilli (LB) using oral specimens from young children with and without visible dental caries. METHODS: Using cotton swabs to collect oral microbial specimens from children 10 to 36 months old, microbial counts of CT and GS were compared with caries experience of the subjects. Contamination levels by non-MS or non-LB isolates on CT and GS were also determined. The CT employed were: (1) CRT bacteria for MS and LB; (2) CarioCheck Plus for MS and LB; and (3) Dentocult SM and Mucount for MS. RESULTS: All CT and GS for MS represented caries status of the participants (P<.001, Fisher exact test; P<.015 linear regression), whereas only GS for LB showed significant association with caries status (P<.001, Fisher exact test; P<.001, linear regression). Non-MS or non-LB isolates were observed on most media, and CT usually exhibited higher contaminant levels than GS. Dentocult SM and Mucount did not harbor contaminants. CONCLUSIONS: Despite contamination, CT and GS for MS and GS for LB exhibited satisfactory outcomes based on cross-sectional caries experience of infants and toddlers.

Evaluation of microbiological screening systems using dental plaque specimens from young children aged 6-36 months.

Using cotton swab specimens of dental plaque from children aged 6-36 months, four commercial chairside tests for oral bacteria were evaluated by comparison with conventional selective culture: mitis salivarius kanamycin bacitracin agar for mutans streptococci and Rogosa SL agar for lactobacilli. Representative colonies of all isolates were identified by commercial identification kits. According to qualitative evaluations, all chairside tests for mutans streptococci were effective in our population. Those for lactobacilli were not as effective, due mainly to a high recovery of yeast contaminants.

Collaborative investigation of the accuracy and reproducibility of Sceptor Breakpoint susceptibility panels.

A combination Sceptor Breakpoint/ID panel (Johnston Laboratories, Inc., Towson, Md.), which determines interpretive susceptibility results (susceptible, moderately susceptible, and resistant) using two to three selected concentrations of antimicrobial agents, was tested in comparison with full-range Sceptor microdilution MIC panels. The inter- and intralaboratory interpretive reproducibilities for 24 control strains tested in three laboratories on three consecutive days were 97.0 and 95.7%, respectively. The equivalency of breakpoint results to category results obtained by the microdilution MIC procedure for 10,368 control organism-antimicrobial agent comparisons was 94.1%. The level of interpretive agreement between breakpoint and MIC category results using 101 fresh clinical isolates was 97.0% for 51 gram-negative and 50 gram-positive bacteria. Among the total 4,872 clinical organism-antimicrobial agent comparisons, major and very major discrepancies were seen in 0.2% of gram-negative bacteria and very major discrepancies were seen in 0.9% of gram-positive bacteria. All very major discrepancies with gram-positive organisms were associated with trailing endpoints using trimethoprim or sulfisoxazole and staphylococci. The breakpoint concept of testing selective antimicrobial agent concentrations was highly reproducible and accurate and allows for placement of more antimicrobial agents into a panel than is possible with full-dilution MIC testing.