Antibiotic-resistant Pseudomonas in bottled drinking water

Eight different bottled drinking waters were tested weekly over an 8-month period to determine the diversity of their Pseudomonas population and their sensitivity to eight antibiotics used in treating Pseudomonas infections. Nine species of Pseudomonas were recovered, with P. stutzeri (24%) and P. diminuta (18.8%) being the most common isolates. Sensitivity patterns of environmental and clinical isolates were shown to differ to some degree. Statistical analyses indicated a significant effect of specific antibiotic on the size of the inhibition zone, a significant difference between species and size of inhibition zone, and a strong species-antibiotic interaction. Distribution of species within the brands of water was also significantly different in 68% of the paired comparisons.