Relationship between triclosan and susceptibilities of bacteria isolated from hands in the community

Abstract

The possible association between triclosan and bacterial susceptibility to antibiotic was examined among staphylococci and several species of gram-negative bacteria (GNB) isolated from the hands of individuals in a community setting. Hand cultures from individuals randomized to using either antibacterial cleaning and hygiene products (including a hand soap containing 0.2% triclosan) or nonantibacterial cleaning and hygiene products for a 1-year period were taken at baseline and at the end of the year. Although there was no statistically significant association between triclosan MICs and susceptibility to antibiotic, there was an increasing trend in the association the odds ratios (ORs) for all species were compared at baseline (OR = 0.65, 95% confidence interval [95%CI] = 0.33 to 1.27) versus at the end of the year (OR = 1.08, 95%CI = 0.62 to 1.97) and for GNB alone at baseline(OR = 0.66, 95%CI = 0.29 to 1.51) versus the end of year (OR = 2.69, 95%CI = 0.78 to 9.23) regardless of the hand-washing product used. Moreover, triclosan MICs were higher in some of the species compared to earlier reports on household, clinical, and industrial isolates, and some of these isolates had triclosan MICs in the range of concentrations used in consumer products. The absence of a statistically significant association between elevated triclosan MICs and reduced antibiotic susceptibility may indicate that such a correlation does not exist or that it is relatively small among the isolates that were studied. Still, a relationship may emerge after longer-term or higher-dose exposure of bacteria to triclosan in the community setting.

FIG. 1.

Triclosan susceptibilities of representative species found on the hands of both antibacterial and nonantibacterial user groups combined at both baseline and the end of the year. Bars represent the percent of all isolates at the MIC indicated. N, number of isolates tested. The lowest and highest dilutions represent triclosan concentrations of ≤0.0312 and ≥32.0 μg/ml, respectively.

FIG. 2.

Triclosan susceptibilities (percentage of isolates at designated MIC) for S. aureus, S. capitis, S. epidermidis, and A. warneri found on the hands of both antibacterial and nonantibacterial user groups combined at both baseline and the end of the year. The lowest dilution represents an MIC of ≤0.0312 μg/ml. The triclosan MIC was >4 μg/ml for none of the species. Bars: ▪, S. aureus (n = 43); ▧, S. capitis (n = 42); ░⃞, S. epidermidis (n = 73); □, S. warneri (n = 155). n, number of isolates of each species.