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An Ohio State Scenic River Shows Elevated Antibiotic Resistance Genes, Including Acinetobacter Tetracycline and Macrolide Resistance, Downstream of Wastewater Treatment Plant Effluent.

ABSTRACT: The entry of antibiotic resistance genes (ARGs) into aquatic systems has been documented for large municipal wastewater treatment plants (WWTPs), but there is less study of the impact of smaller plants that are situated on small rural rivers. We sampled water metagenomes for ARGs and taxa composition from the Kokosing River, a small rural river in Knox County, Ohio, which has been designated an Ohio State Scenic River for retention of natural character. Samples were obtained 1.0 km upstream, 120 m downstream, and 6.4 km downstream from the effluent release of the Mount Vernon WWTP. ARGs were identified in metagenomes using ShortBRED markers from the comprehensive antibiotic resistance database (CARD) screened against UniPROT. Through all seasons, the metagenome just downstream of the WWTP effluent showed a substantial elevation of at least 15 different ARGs, including 6 ARGs commonly associated with Acinetobacter baumannii, such as msrE, mphE (macrolide resistance), and tet(39) (tetracycline resistance). The ARGs most prevalent near the effluent pipe persisted 6.4 km downriver. Using metagenomic phylogenetic analysis (MetaPhlAn2) clade-specific marker genes, the taxa distribution near the effluent showed elevation of reads annotated as Acinetobacter species as well as gut-associated taxa, Bacteroides and Firmicutes. The ARG levels and taxa prevalence showed little dependence on seasonal chlorination of the effluent. Nitrogen and phosphorus were elevated near the effluent pipe but had no consistent correlation with ARG levels. We show that in a rural river microbiome, year-round wastewater effluent substantially elevates ARGs, including those associated with multidrug-resistant A. baumannii. IMPORTANCE Antibiotic resistance is a growing problem worldwide, with frequent transmission between pathogens and environmental organisms. Rural rivers can support high levels of recreational use by people unaware of inputs from treated wastewater, while wastewater treatment plants (WWTPs) can generate a small but significant portion of flow volume into a river surrounded by forest and agriculture. There is little information on the rural impacts of WWTP effluent on the delivery and transport of antibiotic resistance genes. In our study, the river water proximal to wastewater effluent shows evidence for the influx of multidrug-resistant Acinetobacter baumannii, an opportunistic pathogen of concern for hospitals but also widespread in natural environments. Our work highlights the importance of wastewater effluent in management of environmental antibiotic resistance, even in high quality, rural river systems.

SUBMITTER: Murphy A

PROVIDER: S-EPMC8557926 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Abstract Background Mycoplasma pneumoniae(Mp) is one of the most common causes of LRTI in school aged children, with estimates of up to 20% of cases of community-acquired pneumonia (CAP). Macrolides are the drug of choice for treating Mp infections, but in the last 2 decades there has been emergence of resistance worldwide. Reported rates in USA vary from 3.5 up to 10.8%, but rates in Ohio are unknown. Currently there is no well-established, standardized method for detecting macrolide resistance and antibiotic treatment is empiric because of these limitations. Our goal was to determine the frequency of macrolide resistance in children with Mp respiratory infections in central Ohio. Methods A convenience sample of Mp positive PCR identified by our laboratory-developed assay, obtained from both inpatient and outpatient settings, were selected. These were then cultured using Remel’s SP4 glucose broth and then incubated at 35°C until isolates grew, or for a maximum of 4 weeks. All samples that yield positive cultures were then sequenced for the domain V of the 23S rRNA (nucleotide 1937–2154, accession no. X68422) using Sanger methods and sequences were compared with corresponding region of wildtype reference strain (ATCC 15322). Results For the period of October 2015-March 2017, culture was attempted in 433 PCR-positive samples, and 347 (80%) yield an isolate. Sequencing was performed in those 347 samples and was successful in 334 (96%). A macrolide resistance mutation was detected in 10 samples (3%). From the 10 mutations detected, 7 (70%) were the A2063G mutation, and 3 (30%) were A2064G. We also detected a deletion in A2065 of unknown significance in 3 samples (0.9%). Conclusion In this pediatric population, culture was successful in 80% of PCR positive samples, thus providing isolates for sequencing to be able to assess our local resistance. Our overall Mp resistance was 3%, suggesting that empiric treatment with macrolides is still appropriate in Central Ohio. Additional studies are needed to correlate the presence of these resistance mutations with phenotypic susceptibility testing and clinical outcomes. Disclosures O. Ramilo, Abbvie: Board Member, Consulting fee; Regeneron: Board Member, Consulting fee; Janssen: Board Member and Investigator, Consulting fee and Research grant; NIH: Grant Investigator, Research grant; A. Leber, BioFIre Dia gnostics: Research Contractor and Scientific Advisor, Research support, Speaker honorarium and Travel expenses

Project description:BackgroundIn the United States, an estimated 14,748 wastewater treatment plants (WWTPs) provide wastewater collection, treatment, and disposal service to more than 230 million people. The quality of treated wastewater is often assessed by the presence or absence of fecal indicator bacteria. UV disinfection of wastewater is a common final treatment step used by many wastewater treatment plants in order to reduce fecal coliform bacteria and other pathogens; however, its potential impacts on the total effluent bacterial community are seemingly varied. This is especially important given that urban WWTPs typically return treated effluent to coastal and riverine environments and thus are a major source of microorganisms, genes, and chemical compounds to these systems. Following rainfall, stormflow conditions can result in substantial increases to effluent flow into combined systems.MethodsHere, we conducted a lab-scale UV disinfection on WWTP effluent using UV dosage of 100 mJ/cm2 and monitored the active microbiome in UV-treated effluent and untreated effluent over the course of 48 h post-exposure using 16S rRNA sequencing. In addition, we simulated stormflow conditions with effluent UV-treated and untreated effluent additions to river water and compared the microbial communities to those in baseflow river water. We also tracked the functional profiles of genes involved in tetracycline resistance (tetW) and nitrification (amoA) in these microcosms using RT-qPCR.ResultsWe showed that while some organisms, such as members of the Bacteroidetes, are inhibited by UV disinfection and overall diversity of the microbial community decreases following treatment, many organisms not only survive, but remain active. These include common WWTP-derived organisms such as Comamonadaceae and Pseudomonas. When combined with river water to mimic stormflow conditions, these organisms can persist in the environment and potentially enhance microbial functions such as nitrification and antibiotic resistance.

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An Ohio State Scenic River Shows Elevated Antibiotic Resistance Genes, Including Acinetobacter Tetracycline and Macrolide Resistance, Downstream of Wastewater Treatment Plant Effluent.

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