Assessment of a SARS-CoV-2 wastewater monitoring program in El Paso, Texas, from November 2020 to June 2022.

The border city of El Paso, Texas, and its water utility, El Paso Water, initiated a SARS-CoV-2 wastewater monitoring program to assess virus trends and the appropriateness of a wastewater monitoring program for the community. Nearly weekly sample collection at four wastewater treatment facilities (WWTFs), serving distinct regions of the city, was analyzed for SARS-CoV-2 genes using the CDC 2019-Novel coronavirus Real-Time RT-PCR diagnostic panel. Virus concentrations ranged from 86.7 to 268,000 gc/L, varying across time and at each WWTF. The lag time between virus concentrations in wastewater and reported COVID-19 case rates (per 100,00 population) ranged from 4-24 days for the four WWTFs, with the strongest trend occurring from November 2021 - June 2022. This study is an assessment of the utility of a geographically refined SARS-CoV-2 wastewater monitoring program to supplement public health efforts that will manage the virus as it becomes endemic in El Paso.

A Retrospective, Observational Study of 12 Cases of Expanded-Access Customized Phage Therapy: Production, Characteristics, and Clinical Outcomes.

BACKGROUND: Antimicrobial resistance (AMR) is undermining modern medicine, a problem compounded by bacterial adaptation to antibiotic pressures. Phages are viruses that infect bacteria. Their diversity and evolvability offer the prospect of their use as a therapeutic solution. Reported are outcomes of customized phage therapy for patients with difficult-to-treat antimicrobial resistant infections. METHODS: We retrospectively assessed 12 cases of customized phage therapy from a phage production center. Phages were screened, purified, sequenced, characterized, and Food and Drug Administration-approved via the IND (investigational new drug) compassionate-care route. Outcomes were assessed as favorable or unfavorable by microbiologic and clinical standards. Infections were device-related or systemic. Other experiences such as time to treatment, antibiotic synergy, and immune responses were recorded. RESULTS: Fifty requests for phage therapy were received. Customized phages were generated for 12 patients. After treatment, 42% (5/12) of cases showed bacterial eradication and 58% (7/12) showed clinical improvement, with two-thirds of all cases (66%) showing favorable responses. No major adverse reactions were observed. Antibiotic-phage synergy in vitro was observed in most cases. Immunological neutralization of phages was reported in 5 cases. Several cases were complicated by secondary infections. Complete characterization of the phages (morphology, genomics, and activity) and their production (methods, sterility, and endotoxin tests) are reported. CONCLUSIONS: Customized phage production and therapy was safe and yielded favorable clinical or microbiological outcomes in two-thirds of cases. A center or pipeline dedicated to tailoring the phages against a patient's specific AMR bacterial infection may be a viable option where standard treatment has failed.

Structure of the Bacillus anthracis Sortase A Enzyme Bound to Its Sorting Signal: A FLEXIBLE AMINO-TERMINAL APPENDAGE MODULATES SUBSTRATE ACCESS.

The endospore forming bacterium Bacillus anthracis causes lethal anthrax disease in humans and animals. The ability of this pathogen to replicate within macrophages is dependent upon the display of bacterial surface proteins attached to the cell wall by the B. anthracis Sortase A ((Ba)SrtA) enzyme. Previously, we discovered that the class A (Ba)SrtA sortase contains a unique N-terminal appendage that wraps around the body of the protein to contact the active site of the enzyme. To gain insight into its function, we determined the NMR structure of (Ba)SrtA bound to a LPXTG sorting signal analog. The structure, combined with dynamics, kinetics, and whole cell protein display data suggest that the N terminus modulates substrate access to the enzyme. We propose that it may increase the efficiency of protein display by reducing the unproductive hydrolytic cleavage of enzyme-protein covalent intermediates that form during the cell wall anchoring reaction. Notably, a key active site loop (ß7/ß8 loop) undergoes a disordered to ordered transition upon binding the sorting signal, potentially facilitating recognition of lipid II.

Genomic and Functional Characterization of Vancomycin-Resistant Enterococci-Specific Bacteriophages in the Galleria mellonella Wax Moth Larvae Model.

Phages are naturally occurring viruses that selectively kill bacterial species without disturbing the individual's normal flora, averting the collateral damage of antimicrobial usage. The safety and the effectiveness of phages have been mainly confirmed in the food industry as well as in animal models. In this study, we report on the successful isolation of phages specific to Vancomycin-resistant Enterococci, including Enterococcus faecium (VREfm) and Enterococcus faecalis from sewage samples, and demonstrate their efficacy and safety for VREfm infection in the greater wax moth Galleria mellonella model. No virulence-associated genes, antibiotic resistance genes or integrases were detected in the phages' genomes, rendering them safe to be used in an in vivo model. Phages may be considered as potential agents for therapy for bacterial infections secondary to multidrug-resistant organisms such as VREfm.

Metabolic profiling reveals nutrient preferences during carbon utilization in Bacillus species.

The genus Bacillus includes species with diverse natural histories, including free-living nonpathogenic heterotrophs such as B. subtilis and host-dependent pathogens such as B. anthracis (the etiological agent of the disease anthrax) and B. cereus, a cause of food poisoning. Although highly similar genotypically, the ecological niches of these three species are mutually exclusive, which raises the untested hypothesis that their metabolism has speciated along a nutritional tract. Here, we developed a pipeline for quantitative total assessment of the use of diverse sources of carbon for general metabolism to better appreciate the "culinary preferences" of three distinct Bacillus species, as well as related Staphylococcus aureus. We show that each species has widely varying metabolic ability to utilize diverse sources of carbon that correlated to their ecological niches. This approach was applied to the growth and survival of B. anthracis in a blood-like environment and find metabolism shifts from sugar to amino acids as the preferred source of energy. Finally, various nutrients in broth and host-like environments are identified that may promote or interfere with bacterial metabolism during infection.

Antiviral Resistance and Phage Counter Adaptation to Antibiotic-Resistant Extraintestinal Pathogenic Escherichia coli.

Extraintestinal pathogenic Escherichia coli (ExPEC), often multidrug resistant (MDR), is a leading cause of urinary tract and systemic infections. The crisis of emergent MDR pathogens has led some to propose bacteriophages as a therapeutic. However, bacterial resistance to phage is a concerning issue that threatens to undermine phage therapy. Here, we demonstrate that E. coli sequence type 131, a circulating pandemic strain of ExPEC, rapidly develops resistance to a well-studied and therapeutically active phage (ϕHP3). Whole-genome sequencing of the resisters revealed truncations in genes involved in lipopolysaccharide (LPS) biosynthesis, the outer membrane transporter ompA, or both, implicating them as phage receptors. We found ExPEC resistance to phage is associated with a loss of fitness in host microenvironments and attenuation in a murine model of systemic infection. Furthermore, we constructed a novel phage-bacterium bioreactor to generate an evolved phage isolate with restored infectivity to all LPS-truncated ExPEC resisters. This study suggests that although the resistance of pandemic E. coli to phage is frequent, it is associated with attenuation of virulence and susceptibility to new phage variants that arise by directed evolution.IMPORTANCE In response to the rising crisis of antimicrobial resistance, bacteriophage (phage) therapy has gained traction. In the United States, there have been over 10 cases of largely successful compassionate-use phage therapy to date. The resilience of pathogens allowing their broad antibiotic resistance means we must also consider resistance to therapeutic phages. This work fills gaps in knowledge regarding development of phage resisters in a model of infection and finds critical fitness losses in those resisters. We also found that the phage was able to rapidly readapt to these resisters.

Phage-Antibiotic Synergy Is Driven by a Unique Combination of Antibacterial Mechanism of Action and Stoichiometry.

The continued rise in antibiotic resistance is precipitating a medical crisis. Bacteriophage (phage) has been hailed as one possible therapeutic option to augment the efficacy of antibiotics. However, only a few studies have addressed the synergistic relationship between phage and antibiotics. Here, we report a comprehensive analysis of phage-antibiotic interaction that evaluates synergism, additivism, and antagonism for all classes of antibiotics across clinically achievable stoichiometries. We combined an optically based real-time microtiter plate readout with a matrix-like heat map of treatment potencies to measure phage and antibiotic synergy (PAS), a process we term synography. Phage-antibiotic synography was performed against a pandemic drug-resistant clonal group of extraintestinal pathogenic Escherichia coli (ExPEC) with antibiotic levels blanketing the MIC across seven orders of viral titers. Our results suggest that, under certain conditions, phages provide an adjuvating effect by lowering the MIC for drug-resistant strains. Furthermore, synergistic and antagonistic interactions are highly dependent on the mechanism of bacterial inhibition by the class of antibiotic paired to the phage, and when synergism is observed, it suppresses the emergence of resistant cells. Host conditions that simulate the infection environment, including serum and urine, suppress PAS in a bacterial growth-dependent manner. Lastly, two different related phages that differed in their burst sizes produced drastically different synograms. Collectively, these data suggest lytic phages can resuscitate an ineffective antibiotic for previously resistant bacteria while also synergizing with antibiotics in a class-dependent manner, processes that may be dampened by lower bacterial growth rates found in host environments.IMPORTANCE Bacteriophage (phage) therapy is a promising approach to combat the rise of multidrug-resistant bacteria. Currently, the preferred clinical modality is to pair phage with an antibiotic, a practice thought to improve efficacy. However, antagonism between phage and antibiotics has been reported, the choice of phage and antibiotic is not often empirically determined, and the effect of the host factors on the effectiveness is unknown. Here, we interrogate phage-antibiotic interactions across antibiotics with different mechanisms of action. Our results suggest that phage can lower the working MIC for bacterial strains already resistant to the antibiotic, is dependent on the antibiotic class and stoichiometry of the pairing, and is dramatically influenced by the host microenvironment.

Tailored Antibacterials and Innovative Laboratories for Phage (Φ) Research: Personalized Infectious Disease Medicine for the Most Vulnerable At-Risk Patients.

Mutation is the most powerful driver of change for life on Earth. Pathogenic bacteria utilize mutation as a means to survive strong live-die selective pressures generated by chemical antibiotics. As such, the traditional drug-making pipeline, characterized by significant financial and time investment, is insufficient to keep pace with the rapid evolution of bacterial resistance to structurally fixed and chemically unmalleable antibacterial compounds. In contrast, the genetic diversity and adaptive mutability of the bacteriophage can be leveraged to not only overcome resistance but also used for the development of enhanced traits that increase lytic potential and therapeutic efficacy in relevant host microenvironments. This is the fundamental premise behind Baylor College of Medicine's Tailored Antibacterials and Innovative Laboratories for Phage (Φ) Research (TAILΦR) initiative. In this perspective, we outline the concept, structure, and process behind TAILΦR's attempt to generate a personalized therapeutic phage that addresses the most clinically challenging of bacterial infections.

Constructing and Characterizing Bacteriophage Libraries for Phage Therapy of Human Infections.

Phage therapy requires libraries of well-characterized phages. Here we describe the generation of phage libraries for three target species: Escherichia coli, Pseudomonas aeruginosa, and Enterobacter cloacae. The basic phage characteristics on the isolation host, sequence analysis, growth properties, and host range and virulence on a number of contemporary clinical isolates are presented. This information is required before phages can be added to a phage library for potential human use or sharing between laboratories for use in compassionate use protocols in humans under eIND (emergency investigational new drug). Clinical scenarios in which these phages can potentially be used are discussed. The phages presented here are currently being characterized in animal models and are available for eINDs.