Understanding the distribution of positiveLegionellasamples in healthcare-premise water systems: Using statistical analysis to determine a distribution forLegionellaand to support sample size recommendations
| Autor: | Ursula Lauper, Dylan J Nagy, Neculai Codru, David M. Dziewulski |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Microbiology (medical)
Specific test biology Distribution (number theory) Epidemiology Legionella Negative binomial distribution 030501 epidemiology biology.organism_classification Poisson distribution 03 medical and health sciences symbols.namesake 0302 clinical medicine Infectious Diseases Sample size determination Statistics symbols Cutoff Statistical analysis 030212 general & internal medicine 0305 other medical science Mathematics |
| Zdroj: | Infection Control & Hospital Epidemiology. 42:63-68 |
| ISSN: | 1559-6834 0899-823X |
| DOI: | 10.1017/ice.2020.384 |
| Popis: | Objective:To significantly fit a statistical distribution to the proportion of positiveLegionellasamples in a series of water samples from multiple facility-premise water systems.Design:Statistical fit test.Setting:A hospital and associated long-term care facility (LTCF) in New York State, as well as temporal and culture data from a deidentified hospital site supplied by one of the vendor laboratories.Methods:Culture samples (n = 1,393) were segmented into 139 test cycles with roughly 10 samples in each. The proportion of positive samples was standardized to 25 total samples per test to give a distribution of discrete values. These values were analyzed for fit with the following discrete distributions: Poisson, negative binomial, geometric, and zero-inflated Poisson.Results:The zero-inflated Poisson distribution fitted to the copper–silver ionization (CSI)-treated and untreated test cycles indicates that 88% of the expected positive proportions should occur by the 30% cutoff (rounded up to 8 positive samples among 25 total samples), similar to the 93% expectation for just CSI-treated test cycles. The other treatment in these data (chlorine dioxide) was not effective in treatingLegionellain the sampled buildings, and if there is an underlying distribution to these specific test cycles, it is not the zero-inflated Poisson distribution.Conclusions:In a well-maintained or well-treated premise water distribution system, ~30% or lower proportion of positiveLegionellasamples should occur. Anything above that cutoff is either very unlikely or not expected at all and indicates a problem in the water system. |
| Databáze: | OpenAIRE |
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