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1.
J Water Health ; 20(4): 657-669, 2022 Apr.
Article in English | MEDLINE | ID: mdl-35482382

ABSTRACT

The occurrence of amoeba, Naegleria fowleri, in sediment samples from Lake Pontchartrain in Louisiana was investigated. This amoeba is pathogenic and can cause primary amoebic meningoencephalitis. In this study, quantitative polymerase chain reaction methods were used to test for the prevalence of Naegleria fowleri, HF183, and E. coli. N. fowleri was detected in 51.25% of our sediment samples. Illumina sequencing of sediment samples revealed ten different phyla, with Cyanobacteria being the most predominant at sites that generally presented with the highest median N. fowleri concentrations. N. fowleri was however strongly negatively correlated with HF183 (r = -0.859, p < 0.001). Whenever sediment E. coli concentrations were below 1.54 Log GC/g, there was only a 37.5% chance that N. fowleri would be detected in the same sample. When sediment E. coli concentrations exceeded 2.77 Log GC/g, the chances of detecting N. fowleri in the same sample increased to 90%, potentially suggesting predatory activity by the amoeba. The effect of temperature was observed to be different in relation to observed N. fowleri concentrations and detection rates. Although sediment samples collected during periods of higher temperatures had significantly lower mean N. fowleri concentrations (2.7 Log GC/g) compared to those collected at lower temperatures (3.7 Log GC/g, t(39) = 4.167, p < 0.001), higher N. fowleri detection rates in the overall samples were observed at higher temperatures (>19.1 °C) than at lower temperatures (<19.1 °C).


Subject(s)
Amoeba , Naegleria fowleri , Escherichia coli , Feces , Lakes
2.
J Water Health ; 18(5): 820-834, 2020 Oct.
Article in English | MEDLINE | ID: mdl-33095203

ABSTRACT

Private well water systems in rural areas that are improperly maintained will result in poor drinking water quality, loss of water supply, and pose human health risk. The purpose of this study was to investigate the occurrence of fecal indicator bacteria (FIB) and opportunistic pathogens in private well water in rural areas surrounding New Orleans, Louisiana. Our results confirmed the ubiquitous nature of Legionella (86.7%) and mycobacteria (68.1%) in private well water in the study area, with gene concentration ranged from 0.60 to 5.53 and 0.67 to 5.95 Log10 of GC/100 mL, respectively. Naegleria fowleri target sequence was detected in 16.8% and Escherichia coli was detected in 43.4% of the water samples. Total coliform, as well as Legionella and mycobacteria genetic markers' concentrations were significantly reduced by 3-minute flushing. Next-generation sequencing (NGS) data indicated that the abundance of bacterial species was significantly increased in water collected in kitchens compared with samples from wells directly. This study provided integrated knowledge on the persistence of pathogenic organisms in private well water. Further study is needed to explore the presence of clinical species of those opportunistic pathogens in private well water systems to elucidate the health risk.


Subject(s)
Drinking Water , Sanitary Engineering , Humans , Legionella/genetics , Louisiana , Water Supply
3.
Environ Sci Pollut Res Int ; 26(10): 10188-10197, 2019 Apr.
Article in English | MEDLINE | ID: mdl-30758793

ABSTRACT

Wastewater discharge evidently increased bacterial diversity in the receiving waterbodies. The objective of this study was to evaluate the effectiveness of a constructed wetland in reducing fecal indicator bacteria (FIB) and antibiotic resistant genes (ARGs). We determined the prevalence and attenuation of fecal indicator bacteria including Escherichia coli and enterococci, along with ARGs, and human-associated Bacteroidales (HF183) markers by quantitative polymerase chain reaction (qPCR) method. Three types of water samples (inlet, intermediate, and outlet) from a constructed wetland were collected once a month from May to December in 2013. The overall reduction of E. coli was 50.0% based on culture method. According to the qPCR result, the overall removal rate of E. coli was only 6.7%. Enterococci were found in 62.5% of the wetland samples. HF183 genetic marker was detected in all final effluent samples with concentration ranging from 1.8 to 4.22 log10 gene copies (GC)/100 ml. Of the ARGs tested, erythromycin resistance genes (ermF) were detected in 79.2% of the wetland samples. The class 1 integrase (intI1) was detected in all water samples with concentration ranging from 0.83 to 5.54 log10 GC/100 ml. The overall removal rates of enterococci, HF183, intI1, and ermF were 84.0%, 66.6%, 67.2%, and 13.1%, respectively.


Subject(s)
Drug Resistance, Bacterial/genetics , Genes, Bacterial , Waste Disposal, Fluid/methods , Water Pollutants/analysis , Wetlands , Anti-Bacterial Agents , Bacteria/genetics , Enterococcus , Escherichia coli , Feces/microbiology , Humans , Wastewater/microbiology
4.
Mar Pollut Bull ; 129(2): 655-663, 2018 Apr.
Article in English | MEDLINE | ID: mdl-29126560

ABSTRACT

Water quality in Lake Pontchartrain was deteriorating and recreational activities along the beach were restricted by the end of the 20th Century. A microbial source tracking (MST) study was conducted to determine the fecal contamination sources at public beach of the lake, so that effective pollution control strategies can be developed. Water samples were collected over an eight-month period at ten locations along the lake in 2016 and 2017. E. coli and Enterococcus were detected in 90.6% (culture) and 97.5% (qPCR), 95.8% (culture) and 91.8% (qPCR) of water samples from all sampling sites, respectively. Significant positive relationship between E. coli and Enterococcus results was observed for both qPCR and culture methods. HF183 marker was detected in 94.3% water samples (149 of 158), with concentrations ranging from 29.0 to 6073.5GC/100ml and from 129.8 to 38,465.6GC/100ml in summer and winter, respectively. The results also indicate that significant rainfall events have the potential to supply considerable loads of fecal bacteria to lake waters. Further research is needed to determine the contribution of other animals to fecal contamination in the region.


Subject(s)
Environmental Monitoring/methods , Feces/microbiology , Lakes/microbiology , Water Microbiology/standards , Water Pollution/analysis , Animals , Enterococcus/isolation & purification , Escherichia coli/isolation & purification , Humans , Lakes/chemistry , Louisiana , Recreation , Water Quality
5.
Sci Total Environ ; 622-623: 8-16, 2018 May 01.
Article in English | MEDLINE | ID: mdl-29220778

ABSTRACT

Brackish water samples from Lake Pontchartrain in Louisiana were assessed for the presence of pathogenic amoeba Naegleria fowleri, which causes primary amoebic meningoencephalitis (PAM). In our study, quantitative polymerase chain reaction (qPCR) methods were used to determine N. fowleri, E. coli, and enterococci in water collected from Lake Pontchartrain. N. fowleri target sequence was detected in 35.4% (56/158) of the water samples from ten sites around the lake. Statistically significant positive correlations between N. fowleri concentration and water temperature as well as E. coli (qPCR) were observed. Multiple linear regression (MLR) model shows seasonal factor (summer or winter) has significant effect on the concentration of N. fowleri, E. coli and enterococci (qPCR) concentration. Significant positive relationships between E. coli and enterococci was observed from both qPCR (r=0.25) and culture based method (r=0.54). Meanwhile, significant positive correlation between qPCR and culture based methods for enterococci concentration was observed (r=0.33). In our study, water temperature and E. coli concentration were indicative of N. fowleri concentrations in brackish water environment. Future research is needed to determine whether sediment is a source of N. fowleri found in the water column.


Subject(s)
Enterococcus/isolation & purification , Environmental Monitoring , Escherichia coli/isolation & purification , Feces/microbiology , Lakes/microbiology , Naegleria fowleri/isolation & purification , Louisiana , Polymerase Chain Reaction , Saline Waters
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