Evaluating Water Lead Levels During the Flint Water Crisis.

In April 2014, the drinking water source in Flint, Michigan was switched from Lake Huron water with phosphate inhibitors to Flint River water without corrosion inhibitors. The absence of corrosion control and use of a more corrosive source increased lead leaching from plumbing. Our city-wide citizen science water lead results contradicted official claims that there was no problem- our 90th percentile was 26.8 µg/L, which was almost double the Lead and Copper Rule action level of 15 µg/L. Back calculations of a LCR sampling pool with 50% lead pipes indicated an estimated 90th percentile lead value of 31.7 µg/L (±4.3 µg/L). Four subsequent sampling efforts were conducted to track reductions in water lead after the switch back to Lake Huron water and enhanced corrosion control. The incidence of water lead varied by service line material. Between August 2015 and November 2016, median water lead reduced from 3.0 to <1 µg/L for homes with copper service lines, 7.2-1.9 µg/L with galvanized service lines, and 9.9-2.3 µg/L with lead service lines. As of summer 2017, our 90th percentile of 7.9 µg/L no longer differed from official results, which indicated Flint's water lead levels were below the action level.

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

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.

Chlorine Disinfection of Legionella spp., L. pneumophila, and Acanthamoeba under Warm Water Premise Plumbing Conditions.

Premise plumbing conditions can contribute to low chlorine or chloramine disinfectant residuals and reactions that encourage opportunistic pathogen growth and create risk of Legionnaires' Disease outbreaks. This bench-scale study investigated the growth of Legionella spp. and Acanthamoeba in direct contact with premise plumbing materials-glass-only control, cross-linked polyethylene (PEX) pipe, magnesium anode rods, iron pipe, iron oxide, pH 10, or a combination of factors. Simulated glass water heaters (SGWHs) were colonized by Legionella pneumophila and exposed to a sequence of 0, 0.1, 0.25, and 0.5 mg/L chlorine or chloramine, at two levels of total organic carbon (TOC), over 8 weeks. Legionella pneumophila thrived in the presence of the magnesium anode by itself and or combination with other factors. In most cases, 0.5 mg/L Cl2 caused a significant rapid reduction of L. pneumophila, Legionella spp., or total bacteria (16S rRNA) gene copy numbers, but at higher TOC (>1.0 mg C/L), a chlorine residual of 0.5 mg/L Cl2 was not effective. Notably, Acanthamoeba was not significantly reduced by the 0.5 mg/L chlorine dose.

Contact Transmission of Vaccinia to an Infant Diagnosed by Viral Culture and Metagenomic Sequencing.

Targeted molecular diagnostic tests and accurate immunoassays have transformed the landscape of clinical virology, calling into question the usefulness of traditional viral culture. Here we present a case where viral culture, followed by metagenomic sequencing, was central to the diagnosis of an unexpected viral infection, with significant clinical and public health implications.

Critical Review: Propensity of Premise Plumbing Pipe Materials to Enhance or Diminish Growth of Legionella and Other Opportunistic 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 also 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.

Colonization, Infection, and the Accessory Genome of Klebsiella pneumoniae.

Klebsiella pneumoniae is a Gram-negative pathogen that has a large accessory genome of plasmids and chromosomal gene loci. This accessory genome divides K. pneumoniae strains into opportunistic, hypervirulent, and multidrug-resistant groups and separates K. pneumoniae from two closely related species, Klebsiella variicola and Klebsiella quasipneumoniae. Some strains of K. pneumoniae act as opportunistic pathogens, infecting critically ill and immunocompromised patients. These K. pneumoniae are a common cause of health-care associated infections including pneumonia, urinary tract infections (UTIs), and bloodstream infections. K. variicola and K. quasipneumoniae are often clinically indistinguishable from opportunistic K. pneumoniae. Other strains of K. pneumoniae are hypervirulent, infecting healthy people in community settings and causing severe infections including pyogenic liver abscess, endophthalmitis, and meningitis. A third group of K. pneumoniae encode carbapenemases, making them highly antibiotic-resistant. These strains act as opportunists but are exceedingly difficult to treat. All of these groups of K. pneumoniae and related species can colonize the gastrointestinal tract, and the accessory genome may determine if a colonizing strain remains asymptomatic or progresses to cause disease. This review will explore the associations between colonization and infection with opportunistic, antibiotic-resistant, and hypervirulent K. pneumoniae strains and the role of the accessory genome in distinguishing these groups and related species. As K. pneumoniae infections become progressively more difficult to treat in the face of antibiotic resistance and hypervirulent strains, an increased understanding of the epidemiology and pathogenesis of these bacteria is vital.

Identification of Pathogenicity-Associated Loci in Klebsiella pneumoniae from Hospitalized Patients.

Despite insights gained through experimental models, the set of bacterial genes important for human infection is unclear for many of our most threatening pathogens. Klebsiella pneumoniae is a leading cause of health care-associated infections (HAIs) and commonly colonizes hospitalized patients, but the factors that determine whether a particular isolate causes disease or remains a colonizer are poorly understood. To identify bacterial genes associated with K. pneumoniae infection, a case-control study was performed comparing infected and asymptomatic colonized patients. Comparative bacterial genomics was combined with a conditional logit model that identified patient factors differentiating cases from controls. This method identified five gene loci associated with infection after adjustment for patient factors, including a psicose sugar utilization locus that was validated as a fitness factor during mouse lung infection. These results indicate that bacterial genome-wide association studies of patients can identify loci associated with HAIs and important in infection models. IMPORTANCE Klebsiella pneumoniae is a common cause of infections in the health care setting. This work supports a paradigm for K. pneumoniae pathogenesis where the accessory genome, composed of genes present in some but not all isolates, influences whether a strain causes infection or asymptomatic colonization, after accounting for patient-level factors. Identification of patients at high risk of infection could allow interventions to prevent or rapidly treat K. pneumoniae infections.

Molecular Epidemiology of Colonizing and Infecting Isolates of Klebsiella pneumoniae.

Klebsiella pneumoniae is among the most common causes of hospital-acquired infections and has emerged as an urgent threat to public health due to carbapenem antimicrobial resistance. K. pneumoniae commonly colonizes hospitalized patients and causes extraintestinal infections such as urinary tract infection, bloodstream infection (septicemia), and pneumonia. If colonization is an intermediate step before infection, then detection and characterization of colonizing isolates could enable strategies to prevent or empirically treat K. pneumoniae infections in hospitalized patients. However, the strength of the association between colonization and infection is unclear. To test the hypothesis that hospitalized patients become infected with their colonizing strain, 1,765 patients were screened for rectal colonization with K. pneumoniae, and extraintestinal isolates from these same patients were collected over a 3-month period in a cohort study design. The overall colonization prevalence was 23.0%. After adjustment for other patient factors, colonization was significantly associated with subsequent infection: 21 of 406 (5.2%) colonized patients later had extraintestinal infection, compared to 18 of 1,359 (1.3%) noncolonized patients (adjusted odds ratio [OR], 4.01; 95% confidence interval, 2.08 to 7.73; P < 0.001). Despite a high diversity of colonizing isolates, 7/7 respiratory, 4/4 urinary, and 2/5 bloodstream isolates from colonized patients matched the patient corresponding rectal swab isolates, based on wzi capsular typing, multilocus sequence typing (MLST), and whole-genome sequence analysis. These results suggest that K. pneumoniae colonization is directly associated with progression to extraintestinal infection. IMPORTANCE K. pneumoniae commonly infects hospitalized patients, and these infections are increasingly resistant to carbapenems, the antibiotics of last resort for life-threatening bacterial infections. To prevent and treat these infections, we must better understand how K. pneumoniae causes disease and discover new ways to predict and detect infections. This study demonstrates that colonization with K. pneumoniae in the intestinal tract is strongly linked to subsequent infection. This finding helps to identify a potential time frame and possible approach for intervention: the colonizing strain from a patient could be isolated as part of a risk assessment, and antibiotic susceptibility testing could guide empirical therapy if the patient becomes acutely ill.

Comparison of time to positivity of the VersaTREK® REDOX 80-mL and the REDOX EZ draw 40-mL blood culture bottles for common bacterial bloodstream pathogens.

The VersaTREK(®) microbial detection system offers 2 media formulations, an aerobic and an anaerobic bottle available in a 40-mL direct draw format and an 80-mL format. The 40-mL EZ Draw(®) bottle can be inoculated with a maximum volume of 5 mL, while the REDOX 80-mL bottle accommodates a 10-mL volume. The effect of volume of blood inoculum on time to positivity (TTP) has not been clearly established with these bottle types. This study utilized simulated blood cultures seeded with clinically relevant microorganisms in human blood to evaluate the impact of inoculum volume and organism load on TTP for the 2 bottle types. For 13/15 organisms, the EZ Draw bottle flagged positive earlier than the REDOX 80-mL bottles. The lower volume of blood inoculum did not negatively impact TTP using the EZ Draw blood culture bottles as compared to REDOX 80-mL bottles.