Despite the arsenal of technologies employed to control foodborne nontyphoidal Salmonella (NTS), infections have not declined in decades. Poultry is the primary source of NTS outbreaks, as well as the fastest growing meat sector worldwide. With recent FDA rules for phasing-out antibiotics in animal production, pressure is mounting to develop new pathogen reduction strategies. We report on a technology to reduce Salmonella enteritidis in poultry. We engineered probiotic E. coli Nissle 1917, to express and secrete the antimicrobial peptide, Microcin J25. Using in vitro experiments and an animal model of 300 turkeys, we establish the efficacy of this technology. Salmonella more rapidly clear the ceca of birds administered the modified probiotic than other treatment groups. Approximately 97% lower Salmonella carriage is measured in a treated group, 14 days post-Salmonella challenge. Probiotic bacteria are generally regarded as safe to consume, are bile-resistant and can plausibly be modified to produce a panoply of antimicrobial peptides now known. The reported systems may provide a foundation for platforms to launch antimicrobials against gastrointestinal tract pathogens, including ones that are multi-drug resistant.

Oncocin is a proline-rich antimicrobial peptide that inhibits protein synthesis by binding to the bacterial ribosome. In this work, the antimicrobial activity of oncocin was improved by systematic peptide mutagenesis and activity evaluation. We found that a pair of cationic substitutions (P4K and L7K/R) improves the activity by 2-4 fold (p<0.05) against multiple Gram-negative bacteria. An in vitro transcription / translation assay indicated that the increased activity was not because of stronger ribosome binding. Rather a cellular internalization assay revealed a higher internalization rate for the optimized analogs thereby suggesting a mechanism to increase potency. In addition, we found that the optimized peptides’ benefit is dependent upon nutrient-depleted media conditions. The molecular design and characterization strategies have broad potential for development of antimicrobial peptides.

Vancomycin‐resistant Enterococcus (VRE) poses a serious threat in hospitals where they densely colonize the intestinal tracts of patients. In vulnerable hosts, these pathogens may translocate to the bloodstream and become lethal. The ability to selectively reduce VRE in the intestinal tracts of patients could potentially prevent many of these translocation events and reduce the spread of the pathogen. Herein, we have engineered Escherichia. coli Nissle 1917 to produce and secrete three antimicrobial peptides, Enterocin A, Enterocin B, and Hiracin JM79, to specifically target and kill Enterococcus. These peptides exhibited potent activity against both Enterococcus faecium and Enterococcus faecalis, the two most prominent species responsible for VRE infections. We first discuss the optimization of the system used to express and secrete the peptides. We then show that by simultaneously expressing these peptides, both E. faecium and E. faecalis were drastically inhibited. We then demonstrate a suppression of the development of resistance when supernatant from the E. coli producer strains was used to treat E. faecium. Finally, we tested the efficacy of the probiotic in a VRE colonization model in mice. These studies showed that administration of the engineered probiotic significantly reduced the levels of both E. faecium and E. faecalis in the feces of male Balb/cJ mice.

Antibiotic-resistant enterococcal infections are a major concern in hospitals where patients with compromised immunity are readily infected. Enterococcus faecium bacteria are of particular interest as these pathogens account for over 80% of vancomycinresistant enterococcal infections. Antimicrobial peptides (AMPs) produced at the site of infection by engineered bacteria may offer a potential alternative to traditional antibiotics for the treatment of resistant bacteria such as E. faecium. For this mode of delivery to be effective, it is essential to identify a suitable protein expression system that can be used in the desired delivery bacterium. In this study, we describe a promising chloride-inducible promoter and its application in the bacterial delivery of AMPs from Lactococcus lactis to reduce counts of E. faecium bacteria in vitro. Reporter gene studies show that at chloride concentrations found within the human intestines, the chloride-inducible promoter exhibits high levels of protein expression compared to those of the commonly used nisin-inducible promoter. These results indicate that this system is powerful and would not require the exogenous administration of an inducer molecule. In its application for AMP production against E. faecium in vitro, L. lactis producing AMPs under the chloride promoter rapidly decreased E. faecium counts by nearly 10,000-fold. As an extension of this application, we also demonstrate the potential in using this type of delivery system in combination with traditional antibiotics to slow the development of resistance. Collectively, this study shows the promise of using a chloride-inducible promoter for the bacterial delivery of AMPs in the body for the treatment of vancomycin-resistant enterococci (VRE) and other antibiotic-resistant bacteria. E nterococcal infections are a rising concern for health care due to the increasing frequency of multidrug-resistant cases. As of 2013, nearly 30% of all reported enterococcal infections were antibiotic resistant (1). This high percentage of resistance is especially disconcerting in hospitals because patients with compromised immune systems or patients who are on antibiotic regimens are particularly susceptible to enterococcal infections (2). Once an infection has occurred, it can be difficult to eradicate not only from the infected patient but also from the entire hospital environment. Antibiotic resistance makes this process even more challenging, and these infections become both more dangerous and costly (3).Enterococcus faecium and Enterococcus faecalis are the causative pathogens of nearly all vancomycin-resistant enterococcal infections (4). While E. faecalis is more prevalent as an infectious agent, E. faecium is more commonly resistant to antibiotics than E. faecalis and is known for its ability to rapidly transfer antibiotic resistance (2). For example, nearly 81% of E. faecium infections are considered vancomycin resistant (VR), compared to only 5% of E. faecalis infections (4). Additionally, E. faecium carrying resistance to ...

Antimicrobial peptides are a promising alternative to traditional antibiotics, but their utility is limited by high production costs and poor bioavailability profiles. Bacterial production and delivery of antimicrobial peptides (AMPs) directly at the site of infection may offer a path for effective therapeutic application. In this study, we have developed a vector that can be used for the production and secretion of seven antimicrobial peptides from both Escherichia coli MC1061 F’ and probiotic E. coli Nissle 1917. The vector pMPES (Modular Peptide Expression System) employs the Microcin V (MccV) secretion system and a powerful synthetic promoter to drive AMP production. Herein, we demonstrate the capacity of pMPES to produce inhibitory levels of MccV, Microcin L (MccL), Microcin N (McnN), Enterocin A (EntA), Enterocin P (EntP), Hiracin JM79 (HirJM79) and Enterocin B (EntB). To our knowledge, this is the first demonstration of such a broadly-applicable secretion system for AMP production. This type of modular expression system could expedite the development of sorely needed antimicrobial technologies.

Vancomycin-resistant enterococci, particularly resistant Enterococcus faecium, pose an escalating threat in nosocomial environments because of their innate resistance to many antibiotics, including vancomycin, a treatment of last resort. Many class IIa bacteriocins strongly target these enterococci and may offer a potential alternative for the management of this pathogen. However, E. faecium's resistance to these peptides remains relatively uncharacterized. Here, we explored the development of resistance of E. faecium to a cocktail of three class IIa bacteriocins: enterocin A, enterocin P, and hiracin JM79. We started by quantifying the frequency of resistance to these peptides in four clinical isolates of E. faecium. We then investigated the levels of resistance of E. faecium 6E6 mutants as well as their fitness in different carbon sources. In order to elucidate the mechanism of resistance of E. faecium to class IIa bacteriocins, we completed whole-genome sequencing of resistant mutants and performed reverse transcription-quantitative PCR (qRT-PCR) of a suspected target mannose phosphotransferase (ManPTS). We then verified this ManPTS's role in bacteriocin susceptibility by showing that expression of the ManPTS in Lactococcus lactis results in susceptibility to the peptide cocktail. Based on the evidence found from these studies, we conclude that, in accord with other studies in E. faecalis and Listeria monocytogenes, resistance to class IIa bacteriocins in E. faecium 6E6 is likely caused by the disruption of a particular ManPTS, which we believe we have identified.

Introduction: BK virus hemorrhagic cystitis is a well-recognized complication in patients undergoing allogeneic HSCT and is associated with significant morbidity. PTCY has been used for GVHD prophylaxis in patients undergoing haploidentical or mismatched unrelated donor HSCT. We hypothesized that PTCY is associated with increased incidence of HC associated with BK virus. Objectives: To identify the risk factors for developing BKHC in allogeneic HSCT To assess the effect of PTCY in development of BKHC in patients with myeloablative (MA) regimen containing total body irradiation (TBI) To evaluate the risk of concurrent CMV infection and BKHC in allogeneic HSCT with MA conditioning regimen Methods: We identified 116 consecutive patients who underwent allogeneic HSCT at our institution between January 2015 and July 2018. The MA regimen (n=42) consisted of fludarabine 50 mg/m 2 /day IV for 5 days and busulfan 3.2 mg/kg/day IV for 4 days with or without TBI of 200 cGy/day for 2 days (FBT or FB4). The reduced intensity conditioning (RIC) regimen (n=74) consisted of fludarabine 30 mg/m 2 /day IV for 5 days and busulfan 3.2 mg/kg/day IV for 2 days (FB2). In terms of GVHD prophylaxis all recipients except those undergoing haploidentical and mismatched unrelated transplant received Thymoglobulin 2 mg/ kg/daily IV days-2,-1 and 0 (n=80). Recipients of haplo-related and mismatched unrelated donor transplantation received cyclophosphamide 50 mg/kg IV on day +3 and +4 along with Mesna (n=36). All patients received post-transplant immunosuppression with Tacrolimus and Mycophenolate Mofetil. Patients with urinary symptoms were tested for BKV in urine by PCR. Results: The median age of patients was 56 years (range 20À76). A total of 31% of patients (n=13) received PTCY in FBT group which was similar to 31% of patients (n=23) in FB4-FB2 (p=0.98). Overall 21.5% patients were diagnosed with BKHC. The patients who received ATG, the incidence of BKHC was 27.5% in FBT group and 11.7 % in FB4-FB2 (p=0.073). The patients who received PTCY, the incidence of BKHC was significantly increased to 69.2% in FBT vs 9% in FB4-FB2 (p=0.0001). The risk of developing concurrent CMV viremia and BKHC was increased to 10.3% in FBT compared to 5.8% in FB2-FB4 (p=0.662). The patients who received PTCY following FBT, the incidence of concurrent CMV viremia and BKHC was increased to 23.1%. as compared to 0% with FB2-FB4. Conclusion: Our result shows the addition of PTCY to TBI containing regimen significantly increased the incidence of BKHC. We did not observe increase in the incidence of BKHC in patients receiving PTCY with FB2 or FB4 regimens. Our study revealed an increased incidence of concurrent BKHC and CMV viremia in patients receiving PTCY with FBT which could be due to increased immunosuppression. Our findings suggest that using PTCY as GVHD prophylaxis in patients undergoing MA conditioning regimen including TBI is a risk factor for BKHC.