Health relevance of the presence of fecal coliforms in iced tea and leaf tea

Abstract

In late 1995, fecal coliforms were detected in iced tea obtained from several restaurants in the U.S. On the basis of fecal coliform results, the news media inaccurately and sensationally accused the tea industry of marketing tea containing feces. We analyzed 11 iced-tea samples obtained from fast-food restaurants and 25 dry leaf-tea samples purchased from retail grocers for the presence of coliforms and fecal coliforms. All samples of iced tea contained coliforms and fecal coliforms; most probable numbers of coliforms in iced tea ranged from 210 to >1,100/ml, whereas those of fecal coliforms were 15 to >1,100/ml. Twenty-three of twenty-five leaf-tea samples contained coliforms and fecal coliforms; ranges for positive samples were 3 to 1,100/g and 3 to 460/g, respectively. Two Klebsiella species and three Enterobacter species were isolated from iced tea. Only Klebsiella pneumoniae (93.8% of isolates) and Enterobacter cloacae (6.2%) were isolated from leaf tea. Escherichia coil was not isolated from any of the iced-tea or leaf-tea samples analyzed. The D55°C values of two isolates of K. pneumoniae and three isolates of E. cloacae from leaf tea, when heated in steeped tea, ranged from 3.75 to 5.08 min. Initial populations of up to 5.70 log CFU/ml were reduced to <10 CFU/ml within 5 rain at 65°C. While 23 of 25 (92%) of the leaf-tea samples analyzed contained fetal coliforms, as defined by standard methodology, there is no evidence that leaf tea represents a health hazard. The expected presence in leaf tea of Klebsiella and Enterobacter species, which test positive for the fetal coliform group, should not automatically be construed as indicators of fetal contamination nor as an imminent threat to human health. The presence of coliforms and fetal coliforms in iced tea indicates post-steeping contamination caused by poor sanitation practices in restaurants at which the iced tea was purchased.