Abstract Background Rifaquizinone (RFQ, TNP-2092) is a novel multitargeting drug conjugate in development for the treatment of serious or life-threatening bacterial infections including those caused by gram-positive pathogens that have developed or acquired resistance to commonly used antibiotics and those associated with medical devices. RFQ exerts its antibacterial activity by inhibiting RNA polymerase, DNA gyrase, and topoisomerase IV. The current studies were conducted to evaluate the therapeutic efficacy of RFQ following intra-articular (IA) administration in two rodent prosthetic joint infections models with S. aureus. Methods Female C57BL/6 mice and male Wistar rats were used. Following surgical insertion of a metal wire into the femoral canal, the surgical site was inoculated with approximately 7 log10 CFU of an S. aureus strain. RFQ and control drugs were IA administered into mice and rats starting 7 days post-surgery once daily for 7 and 14 days, respectively. At 24 hours after the last dose, the wire and femur were aseptically removed and processed for bacterial titers. Results In the mice, mean wire and femur counts for the untreated controls at the end of the study were 4.77 and 6.88 log10 CFU, respectively. IA delivered RFQ resulted in mean wire and femur counts that were 2.50-2.72 log10 CFU and 1.71-3.42 log10 CFU lower than the untreated controls, respectively (p ≤ 0.0001). In the rats, mean wire and femur counts for the untreated controls at the end of the study were 6.02 and 5.06 log10 CFU, respectively. RFQ resulted in mean wire and femur counts that were 3.32-5.02 log10 CFU and 1.21-1.96 log10 CFU lower than the untreated controls, respectively (p ≤ 0.01). RFQ administration in the rats resulted in reduced knee swelling and expression of systemic inflammatory markers, a decrease in signs of femoral osteomyelitis and decreased biofilm formation. Doses of RFQ in both species were statistically more effective than vancomycin in reducing the bacterial burden. Conclusion The results of these studies indicate that IA injection of RFQ is effective in treating infections related to orthopedic implants. The studies serve as a basis for the use of RFQ in orthopedic practice and the treatment of serious implant-associated infections. Disclosures William J Weiss, MS, TenNor Therapeutics (Suzhou) Ltd: Investigator Mark E Pulse, MS, TenNor Therapeutics (Suzhou) Ltd: Investigator Phung Nguyen, BS, TenNor Therapeutics (Suzhou) Ltd: Investigator David Valtierra, Master, TenNor Therapeutics (Suzhou) Ltd: Investigator Kelly Peterson, PhD, TenNor Therapeutics (Suzhou) Ltd: Investigator Adaeze Ogbonna, Bachelor, TenNor Therapeutics (Suzhou) Ltd: Investigator Lane Beeman, Bachelor, TenNor Therapeutics (Suzhou) Ltd: Investigator Tianyu Dai, PhD, TenNor Therapeutics (Suzhou) Ltd: Investigator Liaobin Chen, PhD, TenNor Therapeutics (Suzhou) Ltd: Investigator Huan Wang, PhD, TenNor Therapeutics (Suzhou) Ltd: Employee Zhenkun Ma, PhD, TenNor Therapeutics (Suzhou) Ltd: Employee

Abstract Background Rifaquizinone (RFQ, TNP-2092) is a novel multitargeting drug conjugate in development for the treatment of serious or life-threatening bacterial infections including those caused by gram-positive pathogens that have developed or acquired resistance to commonly used antibiotics and those associated with medical devices. RFQ exerts its antibacterial activity by inhibiting RNA polymerase, DNA gyrase, and topoisomerase IV. Current studies sought to evaluate the therapeutic efficacy of RFQ following intraperitoneal (IP) administration for 7- to14-day treatment in a murine model of S. aureus prosthetic joint infection (PJI). Methods K-wire was implanted in right hindlimb femurs of C57/BL6 mice followed by infection with 6.5-6.9 log10 CFU of a fluoroquinolone-sensitive (UNT005-4) or -resistant (UNT002-3) S. aureus strain. Doses of RFQ, ciprofloxacin, vancomycin, and vehicle were IP administered BID for 7 or 14 consecutive days starting 7 or 21 days after infection. Infected wires and femurs were collected and processed for CFU counts from untreated groups at the start of treatment and treated/vehicle groups within 18 hours of the final administered dose. Results In the 7 day UNT005-4 infection study, mean wire and femur counts for the infection group were 4.77 log10 CFU and 7.89 log10 CFU on Day 7 and for vehicle treatment were 5.02 log10 CFU and 6.83 log10 CFU on Day 14. Comparatively, RFQ at doses of 10, 25, and 62.5 mg/kg for 7 days treatment significantly reduced mean wire and femur counts by > 2.40 and > 1.60 log10 CFU. In the 21 day UNT005-4 infection study, compared to the infection and vehicle treatment, the same doses of RFQ administered for 14 days significantly reduced mean counts by >1.02 log10 CFU for wires and > 0.88 log10 CFU for femurs. In the 21 day UNT002-3 infection study, RFQ administered for 14 days significantly reduced mean counts by > 1.50 log10 CFU for wire and > 0.9 log10 CFU for femur. As expected, reduction in mean counts following 7 or 14 days of ciprofloxacin and vancomycin treatments were less than RFQ. Conclusion RFQ IP administered doses significantly reduced wire- and femur-associated counts for both S. aureus strains, and despite UNT002-3 resistant to ciprofloxacin treatment, the RFQ remained efficacious in the murine PJI model. Disclosures Mark E Pulse, MS, TenNor Therapeutics (Suzhou) Ltd: Investigator Phung Nguyen, BS, TenNor Therapeutics (Suzhou) Ltd: Investigator David Valtierra, Master, TenNor Therapeutics (Suzhou) Ltd: Investigator Kelly Peterson, PhD, TenNor Therapeutics (Suzhou) Ltd: Investigator Zhenkun Ma, PhD, TenNor Therapeutics (Suzhou) Ltd: Employee Huan Wang, PhD, TenNor Therapeutics (Suzhou) Ltd: Employee William J Weiss, MS, TenNor Therapeutics (Suzhou) Ltd: Investigator

Borrelia burgdorferi, the spirochetal agent of Lyme disease, utilizes a variety of strategies to evade and suppress the host immune response, which enables it to chronically persist in the host. The resulting immune response is characterized by unusually strong IgM production and a lack of long-term protective immunity. Previous studies in mice have shown that infection with B. burgdorferi also broadly suppresses host antibody responses against unrelated antigens. Here, we show that mice infected with B. burgdorferi and concomitantly immunized with recombinant severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein had an abrogated antibody response to the immunization. To further define how long this humoral immune suppression lasts, mice were immunized at 2, 4, and 6 weeks post-infection. Suppression of host antibody production against the SARS-CoV-2 spike protein peaked at 2 weeks post-infection but continued for all timepoints measured. Antibody responses against the SARS-CoV-2 spike protein were also assessed following antibiotic treatment to determine whether this immune suppression persists or resolves following clearance of B. burgdorferi. Host antibody production against the SARS-CoV-2 spike protein returned to baseline following antibiotic treatment; however, anti-SARS-CoV-2 IgM remained high, comparable to levels found in B. burgdorferi-infected but untreated mice. Thus, our data demonstrate restored IgG responses following antibiotic treatment but persistently elevated IgM levels, indicating lingering effects of B. burgdorferi infection on the immune system following treatment.

A hallmark of effective cancer treatment is the prevention of tumor reoccurrence and metastasis to distal organs, which are responsible for most cancer deaths. However, primary tumor resection is expected to be curative as most solid tumors have been shown both experimentally and clinically to accelerate metastasis to distal organs including the lungs. In this study, we evaluated the efficacy of our engineered nasal nano-vaccine (CpG-NP-Tag) in reducing accelerated lung metastasis resulting from primary tumor resection. Cytosine–phosphate–guanine oligonucleotide [CpG ODN]-conjugated nanoparticle [NP] encapsulating tumor antigen [Tag] (CpG-NP-Tag) was manufactured and tested in vivo using a syngeneic mouse mammary tumor model following intranasal delivery. We found that our nasal nano-vaccine (CpG-NP-Tag), compared to control NPs administered after primary mammary tumor resection, significantly reduced lung metastasis in female BALB/c mice subjected to surgery (surgery mice). An evaluation of vaccine efficacy in both surgery and non-surgery mice revealed that primary tumor resection reduces CD11b+ monocyte-derived suppressor-like cell accumulation in the lungs, allowing increased infiltration of vaccine-elicited T cells (IFN-γ CD8+ T cells) in the lungs of surgery mice compared to non-surgery mice. These findings suggest that the combination of the target delivery of a nasal vaccine in conjunction with the standard surgery of primary tumors is a plausible adjunctive treatment against the establishment of lung metastasis.

ABSTRACT Cryptococcosis, caused by fungi of the genus Cryptococcus , manifests in a broad range of clinical presentations, including severe pneumonia and disease of the central nervous system (CNS) and other tissues (bone and skin). Immune deficiency or development of overexuberant inflammatory responses can result in increased susceptibility or host damage, respectively, during fungal encounters. Leukotrienes help regulate inflammatory responses against fungal infections. Nevertheless, studies showed that Cryptococcus exploits host 5-lipoxygenase (5-LO), an enzyme central to the metabolism of arachidonic acid into leukotrienes, to facilitate transmigration across the brain–blood barrier. To investigate the impact of host 5-LO on the development of protective host immune responses and mortality during cryptococcosis, wild-type (C57BL/6) and 5-lipoxygenase-deficient (5-LO −/− ) mice were given experimental pulmonary and systemic Cryptococcus sp., infections. Our results showed that 5-LO −/− mice exhibited reduced pathology and better disease outcomes (i.e., no mortality or signs associated with cryptococcal meningoencephalitis) following pulmonary infection with C. deneoformans, despite having detectable yeast in the brain tissues. In contrast, C57BL/6 mice exhibited classical signs associated with cryptococcal meningoencephalitis. Additionally, brain tissues of 5-LO −/− mice exhibited lower levels of cytokines (CCL2 and CCL3) clinically associated with Cryptococcus -related immune reconstitution inflammatory syndrome (C-IRIS). In a systemic mouse model of cryptococcosis, 5-LO −/− mice and those treated with a Federal Drug Administration (FDA)-approved 5-LO synthesis inhibitor, zileuton, displayed significantly reduced mortality compared to C57BL/6 infected mice. These results suggest that therapeutics designed to inhibit host 5-LO signaling could reduce disease pathology and mortality associated with cryptococcal meningoencephalitis. IMPORTANCE Cryptococcosis is a mycosis with worldwide distribution and has a broad range of clinical manifestations, including diseases of the CNS. Globally, there is an estimated 179,000 cases of cryptococcal meningitis, resulting in approximately 112,000 fatalities per annum and 19% of AIDS-related deaths. Understanding how host immune responses are modulated during cryptococcosis is central to mitigating the morbidity and mortality associated with cryptococcosis. Leukotrienes (LTs) have been shown to modulate inflammatory responses during infection. In this study, we show that mice deficient in 5-lipoxygenase (5-LO), an enzyme central to the metabolism of arachidonic acid into leukotrienes, exhibit reduced pathology, disease, and neurological signs associated with cryptococcal meningitis. Additionally, mice given an experimental cryptococcal infection and subsequently treated with an FDA-approved 5-LO synthesis inhibitor exhibited significantly reduced mortality rates. These results suggest that therapeutics designed to inhibit host 5-LO activity could significantly reduce pathology and mortality rates associated with cryptococcal meningitis.

Lung metastasis is a leading cause of cancer-related deaths. Here, we show that intranasal delivery of our engineered CpG-coated tumor antigen (Tag)-encapsulated nanoparticles (NPs)—nasal nano-vaccine—significantly reduced lung colonization by intravenous challenge of an extra-pulmonary tumor. Protection against tumor-cell lung colonization was linked to the induction of localized mucosal-associated effector and resident memory T cells as well as increased bronchiolar alveolar lavage-fluid IgA and serum IgG antibody responses. The nasal nano-vaccine-induced T-cell-mediated antitumor mucosal immune response was shown to increase tumor-specific production of IFN-γ and granzyme B by lung-derived CD8+ T cells. These findings demonstrate that our engineered nasal nano-vaccine has the potential to be used as a prophylactic approach prior to the seeding of tumors in the lungs, and thereby prevent overt lung metastases from existing extra pulmonary tumors.

Colonization of the gut and airways by pathogenic bacteria can lead to local tissue destruction and life-threatening systemic infections, especially in immunologically compromised individuals. Here, we describe an mRNA-based platform enabling delivery of pathogen-specific immunoglobulin A (IgA) monoclonal antibodies into mucosal secretions. The platform consists of synthetic mRNA encoding IgA heavy, light, and joining (J) chains, packaged in lipid nanoparticles (LNPs) that express glycosylated, dimeric IgA with functional activity in vitro and in vivo. Importantly, mRNA-derived IgA had a significantly greater serum half-life and a more native glycosylation profile in mice than did a recombinantly produced IgA. Expression of an mRNA encoded Salmonella-specific IgA in mice resulted in intestinal localization and limited Peyer's patch invasion. The same mRNA-LNP technology was used to express a Pseudomonas-specific IgA that protected from a lung challenge. Leveraging the mRNA antibody technology as a means to intercept bacterial pathogens at mucosal surfaces opens up avenues for prophylactic and therapeutic interventions.

Monoclonal antibody (mAb) therapy is a promising infectious disease intervention strategy but is limited to IgG1 isotypes that have restricted access to mucosal sites. IgA is well-established as the predominant antibody isotype in mucosal secretions but is clinically underutilized. To enable development of IgA-based mAbs, we exploited mRNA platform technology and demonstrated expression of functional, antigen-specific IgA (IgA mRNA ) that can limit bacterial invasion in the intestine and prevent colonization in the lung. Moreover, in vivo IgA mRNA had enhanced serum half-life and a greater degree of sialylation than a recombinantly produced IgA. The results underscore the potential of mRNA-based platforms to deliver protective human mAbs to mucosal surfaces and open new avenues to combat infectious diseases in the face of pervasive antibiotic resistance. One Sentence Summary mRNA-encoded human monoclonal IgA traffics to mucosal tissues and provides protection against bacterial challenge

TNP-2198, a stable conjugate of a rifamycin pharmacophore and a nitroimidazole pharmacophore, has been designed, synthesized, and evaluated as a novel dual-targeted antibacterial agent for the treatment of microaerophilic and anaerobic bacterial infections. TNP-2198 exhibits greater activity than a 1:1 molar mixture of the parent drugs and exhibits activity against strains resistant to both rifamycins and nitroimidazoles. A crystal structure of TNP-2198 bound to a Mycobacterium tuberculosis RNA polymerase transcription initiation complex reveals that the rifamycin portion of TNP-2198 binds to the rifamycin binding site on RNAP and the nitroimidazole portion of TNP-2198 interacts directly with the DNA template-strand in the RNAP active-center cleft, forming a hydrogen bond with a base of the DNA template strand. TNP-2198 is currently in Phase 2 clinical development for the treatment of Helicobacter pylori infection, Clostridioides difficile infection, and bacterial vaginosis.

A major antimicrobial resistance mechanism in Gram-negative bacteria is the production of β-lactamase enzymes. The increasing emergence of β-lactamase-producing multi-drug-resistant "superbugs" has resulted in increases in costly hospital Emergency Department (ED) visits and hospitalizations due to the requirement for parenteral antibiotic therapy for infections caused by these difficult-to-treat bacteria. To address the lack of outpatient treatment, we initiated an iterative program combining medicinal chemistry, biochemical testing, microbiological profiling, and evaluation of oral pharmacokinetics. Lead optimization focusing on multiple smaller, more lipophilic active compounds, followed by an exploration of oral bioavailability of a variety of their respective prodrugs, provided 36 (VNRX-7145/VNRX-5236 etzadroxil), the prodrug of the boronic acid-containing β-lactamase inhibitor 5 (VNRX-5236). In vitro and in vivo studies demonstrated that 5 restored the activity of the oral cephalosporin antibiotic ceftibuten against Enterobacterales expressing Ambler class A extended-spectrum β-lactamases, class A carbapenemases, class C cephalosporinases, and class D oxacillinases.

Coadministration of human secretory IgA (sIgA) together with subtherapeutic vancomycin enhanced survival in the Clostridioides difficile infection (CDI) hamster model. Vancomycin (5 or 10 mg/kg × 5 days) plus healthy donor plasma sIgA/monomeric IgA (TID × 21 days) or hyperimmune sIgA/monomeric IgA (BID × 13 days) enhanced survival. Survival was improved compared to vancomycin alone, P = .018 and .039 by log-rank Mantel-Cox, for healthy and hyperimmune sIgA, respectively. Passive immunization with sIgA (recombinant human secretory component plus IgA dimer/polymer from pooled human plasma) can be administered orally and prevents death in a partially treated CDI hamster model.

There is an urgent need for oral agents to combat resistant Gram-negative pathogens. Here, we describe the characterization of VNRX-5236, a broad-spectrum boronic acid beta-lactamase inhibitor (BLI), and its orally bioavailable etzadroxil prodrug, VNRX-7145. VNRX-7145 is being developed in combination with ceftibuten, an oral cephalosporin, to combat strains of Enterobacterales expressing extended-spectrum beta-lactamases (ESBLs) and serine carbapenemases. VNRX-5236 is a reversible covalent inhibitor of serine beta-lactamases, with inactivation efficiencies on the order of 10(4) M-1 . sec(-1), and prolonged active site residence times (t(1/2), 5 to 46 min). The spectrum of inhibition includes Ambler class A ESBLs, class C cephalosporinases, and class A and D carbapenemases (KPC and OXA-48, respectively). Rescue of ceftibuten by VNRX-5236 (fixed at 4 mu g/ml) in isogenic strains of Escherichia coli expressing class A, C, or D beta-lactamases demonstrated an expanded spectrum of activity relative to oral comparators, including investigational penems, sulopenem, and tebipenem. VNRX-5236 rescued ceftibuten activity in clinical isolates of Enterobacterales expressing ESBLs (MIC90, 0.25 mu g/ml), KPCs (MIC90, 1 mu g/ml), class C cephalosporinases (MIC90, 1 mu g/ml), and OXA-48-type carbapenemases (MIC90, 1 mu g/ml). Frequency of resistance studies demonstrated a low propensity for recovery of resistant variants at 4x the MIC of the ceftibuten/VNRX-5236 combination. In vivo, whereas ceftibuten alone was ineffective (50% effective dose [ED50], >128 mg/kg), ceftibuten/VNRX-7145 administered orally protected mice from lethal septicemia caused by Klebsiella pneumoniae producing KPC carbapenemase (ED50, 12.9mg/kg). The data demonstrate potent, broad-spectrum rescue of ceftibuten activity by VNRX-5236 in clinical isolates of cephalosporin-resistant and carbapenem-resistant Enterobacterales.

Background . Clostridioides difficile infections have become more frequently diagnosed and associated with greater disease severity, which has resulted in an increase burden on the healthcare system. These increases are attributed to the increased prevalence of hypervirulent strains encompassing select ribotypes. These epidemic ribotypes were characterized as hypervirulent due to higher in vitro spore and toxin production, as well as increased incidence, severity and mortality within patients. However, it is unclear whether epidemic ribotypes are truly more virulent than non-epidemic ribotypes in vivo. Furthermore, there is conflicting evidence about the ability of a strain’s in vitro phenotype to be predictive of their in vivo virulence. The goals of the current studies were to determine if epidemic ribotypes are more virulent than other ribotypes in animal models, and whether the in vitro virulence phenotype of an isolate or ribotype predict in vivo virulence. Results. To determine if epidemic strains were truly more virulent than other non-epidemic strains, the in vivo virulence of thirteen C. difficile isolates (7 non-epidemic and 6 epidemic ribotype isolates) were determined in murine (C57BL/6 mice) and hamster (golden Syrian hamster) models of C. difficile infections. The isolates of epidemic ribotype of C. difficile were found to be more virulent in both the murine and hamster models than non-epidemic isolates. In particular, the group of epidemic ribotypes of C. difficile had lower LD 50 values in hamsters. The increased severity of disease was associated with higher levels of Toxin A and Toxin B production found in fecal samples, but not numbers of organisms recovered. The isolates were further characterized for their in vitro virulence phenotypes, e.g. toxin production, growth rates, spore formation and adherence of spores to intestinal epithelial cell lines. Although there were higher levels of toxins produced and greater adherence for the group of epidemic ribotypes, the in vitro profiles of individual isolates were not always predictive of their in vivo virulence. Conclusions. Overall, the group of epidemic ribotypes of C. difficile were more virulent in vivo despite individual isolates having similar phenotypes to the non-epidemic isolates in vitro .

Abstract Background We are developing a series of small nonpeptide mimics of host defense proteins (smHDPs) for antifungal applications. MICs < 0.1 µg/ ml have been demonstrated against multiple yeast and mold species. Their potential therapeutic utility has been evaluated in animal models of disseminated fungal infections. Methods Susceptibility testing against clinical isolates of Candida albicans (CA) and Aspergillus fumigatus (AF) was done according to CLSI guidelines. Cytotoxicity (CC50) in mouse 3T3 and human HepG2 cells was determined in an MTS assay (Promega Cell Titer 96). For candidiasis, neutropenic CD-1 mice were infected IV with 3.5 x 104 CFU CA and test agents were administered subcutaneously (SC) once (QD) or twice (BID) daily beginning 2 hrs post-infection (PI). The positive control was fluconazole (20 mg/kg PO QD). Kidney burdens were measured at 24 hrs PI (n = 5/grp) and survival was measured at 2 weeks after 5 days of treatment (n = 8/grp). For aspergillosis, neutropenic CD-1 mice were infected IV with 4.5 log10 spores AF and test agents were administered SC BID for 5 days beginning 24 hrs PI. The positive control was posaconazole (20 mg/kg PO QD). Liver and kidney fungal burdens were measured 24 hrs after the last dose (n = 10/grp). Results The lead smHDP, FC-5096, has MICs of 0.08 and 0.024 ug/ml, respectively, against the CA and AF clinical isolate strains used in the mouse efficacy studies. Selectivity for antifungal vs. mammalian cell cytotoxicity (MIC/CC50) was >1,000 fold. In the disseminated candidiasis model, FC-5096 significantly reduced fungal kidney burdens relative to untreated mice to levels found at treatment onset (P < 0.0001). Full survival over 2 weeks was observed after 5 days of BID treatment with FC-5096. All untreated mice succumbed between days 3 – 6 PI. Efficacy was comparable to fluconazole. In the disseminated aspergillosis model, FC-5096 produced up to 2.5 log10 reductions in fungal liver burdens and efficacy was significantly better than posaconazole (P = 0.0251). In kidney, both FC-5096 and posaconazole caused > 1.6 log10 reductions in fungal burdens that exceeded the limit of detection. Conclusion The high antifungal potency, low cytotoxicity and robust in vivo efficacy support further study of FC-5096 for clinical development. Disclosures Richard W. Scott, PhD, Fox Chase Chemical Diversity Center (Employee) Simon DP Baugh, PhD, Fox Chase Chemical Diversity Center (Employee) Mark E Pulse, MS, Fox Chase Chemical Diversity Center (Independent Contractor)

Fluoroquinolone treatments induce dysbiosis of the intestinal microbiota, resulting in loss of resistance to colonization by exogenous bacteria such as Clostridioides difficile that may cause severe diarrhea in humans and lethal infection in hamsters. We show here that DAV131A, a charcoal-based adsorbent, decreases the intestinal levels of the fluoroquinolone antibiotics levofloxacin and ciprofloxacin in hamsters, protects their intestinal microbiota, and prevents lethal infection by C. difficile.

Between 2000-2007, Clostridium (now Closteroides) difficile infections have increased by a factor of 400% and have been associated with greater disease severity. These increases are associated to the increased prevalence of the NAP1/BI/027 ribotype (ribotype-027). This ribotype was characterized as hypervirulent, and one reason was the ability to produce greater numbers of spores in vitro. However, it is unclear whether the epidemic ribotype-027 are able to produce greater numbers of spores in vivo, and if this plays a role during clinically relevant treatments. To determine if epidemic strains are able to produce more spores during clinically relevant treatments, the growth and in vivo production of spores of four C. difficile isolates (2 non-epidemic and 2-epidemic) were determined in the hamster model of C. difficile infection (CDI). By using this model, the epidemic isolates of C. difficile were found to produce more spores than the non-epidemic isolates during treatment with vancomycin. The difference in spore numbers in response to the presence of vancomycin also occurred in in vitro cultures. These differences between the epidemic and non-epidemic isolates were consistent despite there being no difference to sensitivity to vancomycin in vitro. Thus, antibiotic treatment promoted higher levels of spores of epidemic isolates in vivo and in vitro than found in non-epidemic isolates, suggesting this difference in response to clinically relevant antibiotics is a factor that contributes to the ribotype-027 being more frequently diagnosed in C. difficile cases.

In Gram-negative bacterial sepsis, production of excess pro-inflammatory cytokines results in hyperinflammation and tissue injury. Anti-inflammatory cytokines such as IL-10 inhibit inflammation and enhance tissue healing. Here, we report a novel approach to treat septicemia associated with intra-abdominal infection in a murine model by delicately balancing pro- and anti-inflammatory cytokines. A novel oligosaccharide compound AVR-25 selectively binds to the TLR4 protein (IC50 = 0.15 µM) in human peripheral blood monocytes and stimulates IL-10 production. Following the cecal ligation and puncture (CLP) procedure, intravenous dosing of AVR-25 (10 mg/kg, 6–12 h post-CLP) alone and in combination with antibiotic imipenem protected both young adult (10–12 week old) and aged (16–18 month old) mice against polymicrobial infection, organ dysfunction, and death. Proinflammatory cytokines (TNF-α, MIP-1, i-NOS) were decreased significantly and restoration of tissue damage was observed in all organs. A decrease in serum C-reactive protein (CRP) and bacterial colony forming unit (CFU) confirmed improved bacterial clearance. Together, these findings demonstrate the therapeutic ability of AVR-25 to mitigate the storm of inflammation and minimize tissue injury with high potential for adjunctive therapy in intra-abdominal sepsis.

Toxin-induced Clostridium difficile infection (CDI) is a major disease characterized by severe diarrhea and high morbidity rates. The aim with this study was to develop an alternative drug for the treatment of CDI. Cows were repeatedly immunized to establish specific immunoglobulin G and A titers against toxins A (TcdA) and B (TcdB) and against C. difficile cells in mature milk or colostrum. The effect of three different concentrations of anti-C. difficile whey protein isolates (anti-CD-WPI) and the standard of care antibiotic vancomycin were investigated in an animal model of CD infected hamsters (6 groups, with 10 hamsters each). WPI obtained from the milk of exactly the same cows pre-immunization and a vehicle group served as negative controls. The survival of hamsters receiving anti-CD-WPI was 50, 80 and 100% compared to 10 and 0% for the control groups, respectively. Vancomycin suppressed the growth of C. difficile and thus protected the hamsters at the time of administration, but 90% of these hamsters nevertheless died shortly after discontinuation of treatment. In contrast, the surviving hamsters of the anti-CD-WPI groups survived the entire study period, although they were treated for only 75 h. The specific antibodies not only inactivated the toxins for initial suppression of CDI, but also provoked the inhibition of C. difficile growth after discontinuation, thus preventing recurrence. Oral administration of anti-CD-WPI is a functional therapy of CDI in infected hamsters for both primary treatment and prevention of recurrence. Thus, anti-CD-WPI could address the urgent unmet medical need for treating and preventing recurrent CDI in humans.

C. difficile is an endospore-forming pathogen, which is becoming a common cause of microbial health-care associated gastrointestinal disease in the United States. Both healthy and symptomatic patients can shed C. difficile spores into the environment, which can survive for long periods, being resistant to desiccation, heat, and disinfectants. In healthcare facilities, environmental contamination with C. difficile is a major concern as a potential source of exposure to this pathogen and risk of disease in susceptible patients. Although hospital-acquired infection is recognized, community-acquired infection is an increasingly recognized health problem. Primary care clinics may be a significant source of exposure to this pathogen; however, there are limited data about presence of environmental C. difficile within clinics. To address the potential for primary care clinics as a source of environmental exposure to virulent C. difficile, we measured the frequency of environmental contamination with spores in clinic examination rooms and hospital rooms in Dallas-Fort Worth (DFW) area of Texas. The ribotypes and presence of toxin genes from some environmental isolates were compared. Our results indicate primary care clinics have higher frequencies of contamination than hospitals. After notification of the presence of C. difficile spores in the clinics and an educational discussion to emphasize the importance of this infection and methods of infection prevention, environmental contamination in clinics was reduced on subsequent sampling to that found in hospitals. Thus, primary care clinics can be a source of exposure to virulent C. difficile, and recognition of this possibility can result in improved infection prevention, potentially reducing community-acquired C. difficile infections and subsequent disease.