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1. Interactive Effects of Copper Pipe, Stagnation, Corrosion Control, and Disinfectant Residual Influenced Reduction of Legionella pneumophila during Simulations of the Flint Water Crisis

   https://doi.org/10.3390/pathogens9090730  

   Martin, Rebekah L. ; Strom, Owen R. ; Pruden, Amy ; Edwards, Marc A. ( September 2020 , Pathogens)

   Flint, MI experienced two outbreaks of Legionnaires’ Disease (LD) during the summers of 2014 and 2015, coinciding with use of Flint River as a drinking water source without corrosion control. Using simulated distribution systems (SDSs) followed by stagnant simulated premise (i.e., building) plumbing reactors (SPPRs) containing cross-linked polyethylene (PEX) or copper pipe, we reproduced trends in water chemistry and Legionella proliferation observed in the field when Flint River versus Detroit water were used before, during, and after the outbreak. Specifically, due to high chlorine demand in the SDSs, SPPRs with treated Flint River water were chlorine deficient and had elevated L. pneumophila numbers in the PEX condition. SPPRs with Detroit water, which had lower chlorine demand and higher residual chlorine, lost all culturable L. pneumophila within two months. L. pneumophila also diminished more rapidly with time in Flint River SPPRs with copper pipe, presumably due to the bacteriostatic properties of elevated copper concentrations caused by lack of corrosion control and stagnation. This study confirms hypothesized mechanisms by which the switch in water chemistry, pipe materials, and different flow patterns in Flint premise plumbing may have contributed to observed LD outbreak patterns.
2. Critical Review: Propensity of Premise Plumbing Pipe Materials to Enhance or Diminish Growth of Legionella and Other Opportunistic Pathogens

   https://doi.org/10.3390/pathogens9110957  

   Cullom, Abraham C. ; Martin, Rebekah L. ; Song, Yang ; Williams, Krista ; Williams, Amanda ; Pruden, Amy ; Edwards, Marc A. ( November 2020 , Pathogens)

   Growth of Legionella pneumophila and other opportunistic pathogens (OPs) in drinking water premise plumbing poses an increasing public health concern. Premise plumbing is constructed of a variety of materials, creating complex environments that vary chemically, microbiologically, spatially, and temporally in a manner likely to influence survival and growth of OPs. Here we systematically review the literature to critically examine the varied effects of common metallic (copper, iron) and plastic (PVC, cross-linked polyethylene (PEX)) pipe materials on factors influencing OP growth in drinking water, including nutrient availability, disinfectant levels, and the composition of the broader microbiome. Plastic pipes can leach organic carbon, but demonstrate a lower disinfectant demand and fewer water chemistry interactions. Iron pipes may provide OPs with nutrients directly or indirectly, exhibiting a high disinfectant demand and potential to form scales with high surface areas suitable for biofilm colonization. While copper pipes are known for their antimicrobial properties, evidence of their efficacy for OP control is inconsistent. Under some circumstances, copper’s interactions with premise plumbing water chemistry and resident microbes can encourage growth of OPs. Plumbing design, configuration, and operation can be manipulated to control such interactions and health outcomes. Influences of pipe materials on OP physiology should alsomore »be considered, including the possibility of influencing virulence and antibiotic resistance. In conclusion, all known pipe materials have a potential to either stimulate or inhibit OP growth, depending on the circumstances. This review delineates some of these circumstances and informs future research and guidance towards effective deployment of pipe materials for control of OPs.« less
3. Heavy Metal Pollution Impacts Soil Bacterial Community Structure and Antimicrobial Resistance at the Birmingham 35th Avenue Superfund Site

   https://doi.org/10.1128/spectrum.02426-22  

   Goswami, Anuradha ; Adkins-Jablonsky, Sarah J. ; Barreto Filho, Marcelo Malisano ; Shilling, Michelle D. ; Dawson, Alex ; Heiser, Sabrina ; O’Connor, Aisha ; Walker, Melissa ; Roberts, Qutia ; Morris, J. Jeffrey ( April 2023 , Microbiology Spectrum)

   Veach, Allison (Ed.)

   ABSTRACT Heavy metals (HMs) are known to modify bacterial communities both in the laboratory and in situ . Consequently, soils in HM-contaminated sites such as the U.S. Environmental Protection Agency (EPA) Superfund sites are predicted to have altered ecosystem functioning, with potential ramifications for the health of organisms, including humans, that live nearby. Further, several studies have shown that heavy metal-resistant (HMR) bacteria often also display antimicrobial resistance (AMR), and therefore HM-contaminated soils could potentially act as reservoirs that could disseminate AMR genes into human-associated pathogenic bacteria. To explore this possibility, topsoil samples were collected from six public locations in the zip code 35207 (the home of the North Birmingham 35th Avenue Superfund Site) and in six public areas in the neighboring zip code, 35214. 35027 soils had significantly elevated levels of the HMs As, Mn, Pb, and Zn, and sequencing of the V4 region of the bacterial 16S rRNA gene revealed that elevated HM concentrations correlated with reduced microbial diversity and altered community structure. While there was no difference between zip codes in the proportion of total culturable HMR bacteria, bacterial isolates with HMR almost always also exhibited AMR. Metagenomes inferred using PICRUSt2 also predicted significantly higher mean relativemore »frequencies in 35207 for several AMR genes related to both specific and broad-spectrum AMR phenotypes. Together, these results support the hypothesis that chronic HM pollution alters the soil bacterial community structure in ecologically meaningful ways and may also select for bacteria with increased potential to contribute to AMR in human disease. IMPORTANCE Heavy metals cross-select for antimicrobial resistance in laboratory experiments, but few studies have documented this effect in polluted soils. Moreover, despite decades of awareness of heavy metal contamination at the EPA Superfund site in North Birmingham, Alabama, this is the first analysis of the impact of this pollution on the soil microbiome. Specifically, this work advances the understanding of the relationship between heavy metals, microbial diversity, and patterns of antibiotic resistance in North Birmingham soils. Our results suggest that polluted soils carry a risk of increased exposure to antibiotic-resistant infections in addition to the direct health consequences of heavy metals. Our work provides important information relevant to both political and scientific efforts to advance environmental justice for the communities that call Superfund neighborhoods home.« less
4. Coupled DNA-labeling and sequencing approach enables the detection of viable-but-non-culturable Vibrio spp. in irrigation water sources in the Chesapeake Bay watershed

   https://doi.org/10.1186/s40793-021-00382-1  

   Malayil, Leena ; Chattopadhyay, Suhana ; Mongodin, Emmanuel F. ; Sapkota, Amy R. ( June 2021 , Environmental Microbiome)

   Nontraditional irrigation water sources (e.g., recycled water, brackish water) may harbor human pathogens, includingVibriospp., that could be present in a viable-but-nonculturable (VBNC) state, stymieing current culture-based detection methods. To overcome this challenge, we coupled 5-bromo-2′-deoxyuridine (BrdU) labeling, enrichment techniques, and 16S rRNA sequencing to identify metabolically-activeVibriospp.in nontraditional irrigation water (recycled water, pond water, non-tidal freshwater, and tidal brackish water). Our coupled BrdU-labeling and sequencing approach revealed the presence of metabolically-activeVibriospp. at all sampling sites. Whereas, the culture-based method only detected vibrios at three of the four sites. We observed the presence ofV. cholerae,V. vulnificus, andV. parahaemolyticususing both methods, whileV. aesturianusandV. shiloniiwere detected only through our labeling/sequencing approach. Multiple other pathogens of concern to human health were also identified through our labeling/sequencing approach includingP. shigelloides,B. cereusandE. cloacae. Most importantly, 16S rRNA sequencing of BrdU-labeled samples resulted inVibriospp. detection even when our culture-based methods resulted in negative detection. This suggests that our novel approach can effectively detect metabolically-activeVibriospp. that may have been present in a VBNC state, refining our understanding of the prevalence of vibrios in nontraditional irrigation waters.
5. Inactivation of Legionella Pneumophila-Harbored by Amoebae Using a Nano-Enabled Alternative Technology

   Saleh, N. B. ; Kirisits, M. J. ; Ayres, C. ( November 2019 , 2019 ASA, CSSA, and SSSA Annual Meeting)

   Legionella pneumophila is a virulent bacterial pathogen that can cause a severe and deadly form of pneumonia called Legionnaires’ disease. Documented cases of Legionnaires’ disease have been rising since 2000. Risk of infection increases when L. pneumophila are harbored inside free-living amoebae, which are resistant to traditional disinfection processes. The ability of amoebae to phagocytose L. pneumophila allows amoebae to act as ‘Trojan horses’ for pathogen transport. This project aims to extract an unintended benefit from low-intensity microwave (MW) radiation (already found in many homes across economic cross-sections) by employing nanomaterials (e.g., silver, copper oxide, and carbon nanotubes) that are capable of harnessing such radiation and localizing the otherwise dissipated energy. In this alternative technology, we hypothesize that amoebae will be lysed via localized interfacial heating, and the released L. pneumophila will be inactivated subsequently by heat, metal ions (from nanoparticle dissolution), and reactive oxygen species (ROS) produced in the process. Traditionally, inactivation of up to 3-logs of planktonic L. pneumophila with dissolved silver requires hours of contact time. This study reports rapid inactivation (in minutes) of 3-log or higher when the planktonic L. pneumophila is subjected to AgNPs (5 mg/L) and MW radiation (2,450 MHz; 70 W). Ensuing phasesmore »of this project will incorporate copper oxide nanoparticles – which are anticipated to increase toxicity akin to copper-silver ionization systems currently employed in hospitals for L. pneumophila control – and enhance inactivation potency with potentially lower microwave radiation input and/or a lower concentration of nanoparticles. Ultimately, the nanomaterials will be immobilized on a plaster of Paris or ceramic surface for flow-through applications for lysing amoebae and inactivating L. pneumophila.« less