Related Experiment Videos
Evaluation of a most-probable-number technique for the enumeration of Pseudomonas aeruginosa
Abstract:
A most-probable-number (MPN) technique was evaluated for detecting and enumerating Pseudomonas aeruginosa in water and wastewater. Both the presumptive and confirmatory media, as described in the 13th edition of Standard Methods for the Examination of Water and Wastewater, as well as modifications of these media were included in evaluations. Various samples of water were tested, namely chlorinated tap water, creek water, and influent to a wastewater treatment plant. Modified media repeatedly gave higher estimated MPNs of P. aeruginosa than media listed in Standard Methods. P. aeruginosa was detected and recovered from all creek water and wastewater samples, but not from tap water samples tested. This organism was determined to be present in as large numbers as the fecal coliforms and in even greater quantities than the fecal streptococci in all samples, whenever MPN estimations were determined from those positive tubes containing the modified confirmatory medium.
Insights
Modified most-probable-number (MPN) methods enhance detection of Pseudomonas aeruginosa in water and wastewater. These improved techniques offer higher bacterial counts than standard methods, revealing significant P. aeruginosa presence in environmental samples.
Area of Science:
- Environmental microbiology
- Water quality assessment
- Bacteriology
Background:
- Pseudomonas aeruginosa is an opportunistic pathogen found in various water environments.
- Accurate detection and enumeration are crucial for assessing water safety.
- Standard Methods for the Examination of Water and Wastewater provide established protocols for bacterial analysis.
Purpose of the Study:
- To evaluate a most-probable-number (MPN) technique for detecting and enumerating Pseudomonas aeruginosa in water and wastewater.
- To compare the efficacy of standard media with modified media for P. aeruginosa quantification.
Main Methods:
- Evaluation of both presumptive and confirmatory media, including modifications, for MPN analysis.
- Testing of various water types: chlorinated tap water, creek water, and wastewater influent.
- Comparison of MPN results obtained from standard and modified media.
Main Results:
- Modified media consistently yielded higher estimated MPNs of P. aeruginosa compared to standard media.
- P. aeruginosa was detected in all creek water and wastewater samples tested.
- No P. aeruginosa was recovered from chlorinated tap water samples.
- In positive samples, P. aeruginosa was found in quantities comparable to or exceeding fecal coliforms and fecal streptococci when using modified confirmatory media.
Conclusions:
- Modified MPN media improve the detection and enumeration of P. aeruginosa in water and wastewater.
- The prevalence of P. aeruginosa in environmental waters necessitates reliable detection methods.
- Modified methods provide a more sensitive assessment of P. aeruginosa contamination levels.