ABSTRACT
Nontuberculous mycobacteria (NTM) are a major cause of opportunistic infection in immunocompromised hosts. Because there is no evidence of person-to-person transmission and NTM have been found in drinking water, the environment is considered a likely source of infection. In this study the widespread occurrence of NTM was examined in drinking water, bottled water, and ice samples. A total of 139 samples were examined for NTM by a membrane filtration culture technique followed by PCR amplification and 16S rRNA sequence determination to identify the isolates. NTM were not detected in bottled water or cisterns but were detected in 54% of the ice samples and 35% of the public drinking-water samples from 21 states. The most frequently occurring isolate was M. mucogenicum (formerly referred to as an M. chelonae-like organism).
Subject(s)
Mycobacterium/classification , Mycobacterium/isolation & purification , Nontuberculous Mycobacteria/isolation & purification , Water Microbiology , Water Supply , Colony Count, Microbial , DNA, Bacterial/genetics , DNA, Ribosomal/genetics , Environmental Microbiology , Mycobacterium/genetics , Nontuberculous Mycobacteria/classification , Nontuberculous Mycobacteria/genetics , Polymerase Chain Reaction/methods , RNA, Ribosomal, 16S/geneticsABSTRACT
Indoxyl-beta-D-glucuronide (indoxyl) was evaluated as a specific chromogen for detection of Escherichia coli by the membrane filter method. In all, 413 colonies were tested from the indoxyl-supplemented media, yielding 93.3% confirmation, as E. coli. Compared with the indoxyl medium, other media gave either much lower recovery with high verification or equal recovery with poor verification.
Subject(s)
Escherichia coli/metabolism , Glucuronates/metabolism , Indoles/metabolism , Bacteriological Techniques , Coloring Agents , Culture Media , Escherichia coli/isolation & purification , Evaluation Studies as Topic , Water MicrobiologyABSTRACT
The Autoanalysis Colilert (AC) test was compared with the membrane filter (MF), 10-tube multiple-tube fermentation (MTF) technique, and the presence-absence test as described in Standard Methods for the Examination of Water and Wastewater for the detection and enumeration of total coliforms in water. The methods were evaluated with 31 samples from seven different sources. Each sample was analyzed by each of the techniques, using replicate 100-ml sample volumes. A total of 582 confirmed tubes were positive by the MTF test, and 533 tubes were positive by the AC test. Statistical analysis of the most-probable-number comparability data showed a statistically significant difference in the number of positive tubes, with the MTF test resulting in more positive tubes. There were no statistically significant differences in precision between the two methods. All the methods were comparable in detection of total coliforms. Levels of heterotrophic bacteria generally encountered in drinking water did not interfere with detection or enumeration of coliforms by the AC test.
