Antibiotic Treatment Failure Research Articles

Deciphering the Drug Delivery Potential of Milk Exosome Nanovesicles for Aminobenzylpenicillin Therapeutic Efficacy against Contagious Staphylococcus Aureus in Bovine Mastitis.

The emergence of antimicrobial resistance and failure of antibiotic treatment are challenging tasks for managing bovine mastitis, which is mainly caused by the contagious Staphylococcus aureus (S. aureus).To overcome these difficulties, there is an urgent need for a novel drug system. In the present study, the aim is to develop next-generation therapeutics against S. aureus by harnessing the drug delivery potential of milk nanovesicles called milk exosomes (mENs). In the present work, a drug system is developed by encapsulating aminobenzylpenicillin (AMP) in mENs (mENs-AMP). Electron microscopy and zeta-sizer results indicate that the size of mENs-AMP ranged from 55.79±2.8 to 85.53±7.4nm. The AMP loading efficiency in mENs is 88.61% with its sustained release. Fluorescence spectroscopy results indicated that mENs are biocompatible with mammary epithelial cells. In vitro studies show that the antibacterial activity and the minimum inhibitory concentrations of mENs-AMP are eleven times greater and four times lower than that of unencapsulated AMP, respectively. The mENs-AMP exhibit significantly higher therapeutic efficacy than AMP at the same dosage and treatment frequency. Validation of this approach is demonstrated in mastitis-affected animals through an observation in the reduction of somatic cell counts and bacterial loads in the milk of treated animals.

Lyophilized fecal microbiome transfer for primary Clostridioides difficile infection: a multicenter randomized controlled trial (DONATE Study)

Background Primary Clostridioides difficile infection (pCDI) carries high recurrence and mortality rates and is globally spread. pCDI is often a consequence of exposure to antibiotics, disrupting the healthy intestinal microbiota composition. Not surprisingly, in this antibiotic-associated infection, failure of the standard antibiotic treatment is high. Frozen fecal microbiota transplantation (FMT), the introduction of the microbial community from a healthy donor, has been shown to be safe and highly effective in cases of recurrent CDI, reaching >90% cumulative success rate. Importantly, FMT has shown potential for intestinal decolonization of multidrug-resistant organisms (MDRO), and/or mitigation of their ability to cause invasive infection. The use of FMT for pCDI, has been tested in small studies, showing promising results. The use of frozen FMT graft is often administered via colonoscopy or enteral (naso-jejunal) tubes, which are invasive procedures, placing significant burden on these often frail patients and the institutions providing the services. Moreover, frozen FMT is hampered by storage needs which limit accessibility and spread. Methods We have developed a lyophilized FMT product (Lyo-FMT - a dry compound that does not need freezing) that retains viability, prolongs the shelf time of the product and improves patient acceptance. In a randomized controlled multicenter trial, we aim to assess the efficacy of Lyo-FMT for pCDI in comparison to standard antibiotic therapy. Expected results This easy-to-administer product will restore the microbial community, fight the infective agent and reduce the overall antibiotic-resistant gene burden. This, in turn, will lower the recurrence rate and decrease carriage of other MDRO, coupled with a reduction in antibiotic use. Data on microbial shifts during treatment will shed light on our understanding of the pathophysiology of the disease. Clinicaltrials.gov registration NCT05709184, 2023-02-24

Triple threat: how diabetes results in worsened bacterial infections.

Diabetes mellitus, characterized by impaired insulin signaling, is associated with increased incidence and severity of infections. Various diabetes-related complications contribute to exacerbated bacterial infections, including hyperglycemia, innate immune cell dysfunction, and infection with antibiotic-resistant bacterial strains. One defining symptom of diabetes is hyperglycemia, resulting in elevated blood and tissue glucose concentrations. Glucose is the preferred carbon source of several bacterial pathogens, and hyperglycemia escalates bacterial growth and virulence. Hyperglycemia promotes specific mechanisms of bacterial virulence known to contribute to infection chronicity, including tissue adherence and biofilm formation. Foot infections are a significant source of morbidity in individuals with diabetes and consist of biofilm-associated polymicrobial communities. Bacteria perform complex interspecies behaviors conducive to their growth and virulence within biofilms, including metabolic cross-feeding and altered phenotypes more tolerant to antibiotic therapeutics. Moreover, the metabolic dysfunction caused by diabetes compromises immune cell function, resulting in immune suppression. Impaired insulin signaling induces aberrations in phagocytic cells, which are crucial mediators for controlling and resolving bacterial infections. These aberrancies encompass altered cytokine profiles, the migratory and chemotactic mechanisms of neutrophils, and the metabolic reprogramming required for the oxidative burst and subsequent generation of bactericidal free radicals. Furthermore, the immune suppression caused by diabetes and the polymicrobial nature of the diabetic infection microenvironment may promote the emergence of novel strains of multidrug-resistant bacterial pathogens. This review focuses on the "triple threat" linked to worsened bacterial infections in individuals with diabetes: (i) altered nutritional availability in diabetic tissues, (ii) diabetes-associated immune suppression, and (iii) antibiotic treatment failure.

Heteroresistance to piperacillin/tazobactam in Klebsiella pneumoniae is mediated by increased copy number of multiple β-lactamase genes.

Piperacillin/tazobactam is a β-lactam/β-lactamase inhibitor combination with a broad spectrum of activity that is often used as empirical and/or targeted therapy among hospitalized patients. Heteroresistance (HR) is a form of antibiotic resistance in which a minority population of resistant cells coexists with a majority susceptible population that has been found to be a cause of antibiotic treatment failure in murine models. To determine the prevalence of HR and mechanisms of HR to piperacillin/tazobactam among Klebsiella pneumoniae bloodstream infection (BSI) isolates. From July 2018 to June 2021, K. pneumoniae piperacillin/tazobactam-susceptible BSI isolates were collected from two tertiary hospitals in Atlanta, GA, USA. Only first isolates from each patient per calendar year were included. Population analysis profiling (PAP) and WGS were performed to identify HR and its mechanisms. Among 423 K. pneumoniae BSI isolates collected during the study period, 6% (25/423) were found to be HR with a subpopulation surviving above the breakpoint. WGS of HR isolates grown in the presence of piperacillin/tazobactam at concentrations 8-fold that of the MIC revealed copy number changes of plasmid-located β-lactamase genes blaCTX-M-15, blaSHV33, blaOXA-1 and blaTEM-1 by tandem gene amplification or plasmid copy number increase. Prevalence of HR to piperacillin/tazobactam among bloodstream isolates was substantial. The HR phenotype appears to be caused by tandem amplification of β-lactamase genes found on plasmids or plasmid copy number increase. This raises the possibility of dissemination of HR through horizontal gene transfer and requires further study.

Designing a conjugate vaccine targeting Klebsiella pneumoniae ST258 and ST11

Klebsiella pneumoniae (K. pneumoniae) is a common bacterium that can cause iatrogenic infection. Recently, the rise of antibiotic resistance among K. pneumoniae strains is one key factor associated with antibiotic treatment failure. Hencefore, there is an urgent need for effective K. pneumoniae vaccines. This study aimed to design a multi-epitope vaccine (MEV) candidate against K. pneumonia by utilizing an immunoinformatics method. In this study, we obtained 15 cytotoxic T lymphocyte epitopes, 10 helper T lymphocyte epitopes, 6 linear B-cell epitopes, and 2 conformational B-cell epitopes for further research. Then, we designed a multi-epitope vaccine composed of a total of 743 amino acids, containing the epitopes linked by GPGPG flexible links and an EAAAK linker to the Cholera Toxin Subunit B coadjuvant.The observed properties of the MEV, including non-allergenicity, high antigenicity, and hydrophilicity, are noteworthy. The improvements in the tertiary structure through structural refinement and disulfide bonding, coupled with promising molecular interactions revealed by molecular dynamics simulations with TLR4, position the MEV as a strong candidate for further investigation against K. pneumoniae.

Antibiotic Switches in Urinary Tract Infection Are Associated With Atypical Symptoms and Emergent Care.

Given worsening global antibiotic resistance, antimicrobial stewardship aims to use the shortest effective duration of the most narrow-spectrum, effective antibiotic for patients with specific urinary symptoms and laboratory testing consistent with urinary tract infection (UTI). Inappropriate treatment and unnecessary antibiotic switching for UTIs harms patients in a multitude of ways. This study sought to analyze antibiotic treatment failures as measured by antibiotic switching for treatment of UTI in emergent and ambulatory care. For this retrospective cohort study, 908 encounters during July 2019 bearing a diagnostic code for UTI/cystitis in a single health care system were reviewed. Urinary and microbiological testing, symptoms endorsed at presentation, and treatments prescribed were extracted from the medical record. Of 908 patients diagnosed with UTI, 64% of patients (579/908) received antibiotics, 86% of which were empiric. All patients evaluated in emergent care settings were prescribed antibiotics empirically in contrast to 71% of patients in ambulatory settings (P < 0.001). Of patients given antibiotics, 89 of 579 patients (15%, 10% of all 908 patients) were switched to alternative antibiotics within 28 days. Emergent care settings and positive urine cultures were significantly associated with increased antibiotic switching. Patients subjected to switching tended to have higher rates of presenting symptoms inconsistent with UTI. Empiric treatment, particularly in an emergent care setting, was frequently inappropriate and associated with increasing rates of antibiotic switching. Given the profound potential contribution to antibiotic resistance, these findings highlight the need for improved diagnostic and prescribing accuracy for UTI.

Intoxication of antibiotic persisters by host RNS inactivates their efflux machinery during infection.

The host environment is of critical importance for antibiotic efficacy. By impacting bacterial machineries, stresses encountered by pathogens during infection promote the formation of phenotypic variants that are transiently insensitive to the action of antibiotics. It is assumed that these recalcitrant bacteria-termed persisters-contribute to antibiotic treatment failure and relapsing infections. Recently, we demonstrated that host reactive nitrogen species (RNS) transiently protect persisters against the action of β-lactam antibiotics by delaying their regrowth within host cells. Here, we discovered that RNS intoxication of persisters also collaterally sensitizing them to fluoroquinolones during infection, explaining the higher efficiency of fluoroquinolones against intramacrophage Salmonella. By reducing bacterial respiration and the proton-motive force, RNS inactivate the AcrAB efflux machinery of persisters, facilitating the accumulation of fluoroquinolones intracellularly. Our work shows that target inactivity is not the sole reason for Salmonella persisters to withstand antibiotics during infection, with active efflux being a major contributor to survival. Thus, understanding how the host environment impacts persister physiology is critical to optimize antibiotics efficacy during infection.

Comparative analysis of genes expression involved in type II toxin-antitoxin system in Staphylococcus aureus following persister cell formation.

The formation of persister cells is the main reason for persistent infections. They are associated with antibiotic treatment failure and subsequently chronic infection. The study aimed to assess the expression of type II toxin/antitoxin (TA) system genes in persister cells of Staphylococcus aureus in the presence of the following antibiotics vancomycin, ciprofloxacin, and gentamicin in exponential and stationary phases. The colony count was used to evaluate the effect of different types of antibiotics on S. aureus persister cell formation during exponential and stationary phases. Moreover, the expression level of TA systems and clpP genes in the persister population in exponential and stationary phases were measured by quantitative reverse transcriptase real-time PCR (qRT-PCR). The results of the study showed the presence of persister phenotype of S. aureus strains in the attendance of bactericidal antibiotics in comparison to the control group during the exponential and stationary phases. Moreover, qRT-PCR resulted in the fact that the role of TA systems involved in the persister cell formation depends on the bacterial growth phase and the type of strain and antibiotic. In total, the present study provides some data on the persister cell formation and the possible role of TA system genes in this process.

Characterization of the dispirotripiperazine derivative PDSTP as antibiotic adjuvant and antivirulence compound against Pseudomonas aeruginosa.

Pseudomonas aeruginosa is a major human pathogen, able to establish difficult-to-treat infections in immunocompromised and people with cystic fibrosis (CF). The high rate of antibiotic treatment failure is due to its notorious drug resistance, often mediated by the formation of persistent biofilms. Alternative strategies, capable of overcoming P. aeruginosa resistance, include antivirulence compounds which impair bacterial pathogenesis without exerting a strong selective pressure, and the use of antimicrobial adjuvants that can resensitize drug-resistant bacteria to specific antibiotics. In this work, the dispirotripiperazine derivative PDSTP, already studied as antiviral, was characterized for its activity against P. aeruginosa adhesion to epithelial cells, its antibiotic adjuvant ability and its biofilm inhibitory potential. PDSTP was effective in impairing the adhesion of P. aeruginosa to various immortalized cell lines. Moreover, the combination of clinically relevant antibiotics with the compound led to a remarkable enhancement of the antibiotic efficacy towards multidrug-resistant CF clinical strains. PDSTP-ceftazidime combination maintained its efficacy in vivo in a Galleria mellonella infection model. Finally, the compound showed a promising biofilm inhibitory activity at low concentrations when tested both in vitro and using an ex vivo pig lung model. Altogether, these results validate PDSTP as a promising compound, combining the ability to decrease P. aeruginosa virulence by impairing its adhesion and biofilm formation, with the capability to increase antibiotic efficacy against antibiotic resistant strains.

Development of colistin resistance via heteroresistance modeling in Klebsiella pneumoniae: A diagnostic study

Purpose: Colistin heteroresistance mediates the failure of antibiotic treatments, is prone to lead to colistin resistance, and has been frequently reported in &lt;i&gt;Klebsiella pneumoniae&lt;/i&gt;. This study investigated origins of the increase in colistin resistance following colistin exposure to colistin-heteroresistant &lt;i&gt;K. pneumoniae&lt;/i&gt;.Methods: A modeled colistin-heteroresistant &lt;i&gt;K. pneumoniae&lt;/i&gt; strain (i.e., mimicking colistin- heteroresistant [m-CL&lt;sup&gt;HR&lt;/sup&gt;]) was generated using a susceptible &lt;i&gt;K. pneumoniae&lt;/i&gt; strain ATCC 10031 and its resistance-induced mutant. Heteroresistance patterns were investigated through population analysis profiling (PAP), competition assays, and fluctuation and stability tests. An &lt;i&gt;in vitro&lt;/i&gt; time-killing assay for colistin was performed for the m-CL&lt;sup&gt;HR&lt;/sup&gt; to identify the change in susceptible and resistant populations before and after colistin exposure.Results: The generated m-CL&lt;sup&gt;HR&lt;/sup&gt; strain showed a typical heteroresistance pattern for colistin in PAP, and its competition assay did not show fitness costs for any population. The ratio of resistant cells to susceptible cells did not deviate significantly from the range of heteroresistance in the fluctuation test, while the ratios of resistant cells preserved their stability. The &lt;i&gt;in vitro&lt;/i&gt; time-killing assay thus showed that the resistant cells increased upon colistin exposure; sequencing analyses confirmed that the surviving resistant cells did not originate from susceptible cells by mutation. This study successfully modeled a colistin-heteroresistant &lt;i&gt;K. pneumoniae&lt;/i&gt; strain, i.e., m-CL&lt;sup&gt;HR&lt;/sup&gt;.Conclusion: In this modeled heteroresistant strain, only the colistin-resistant population survived the colistin treatment—this suggests that the development of colistin resistance from heteroresistant strain is because of the selection of a resistant population and not by the induction of resistance through mutations in susceptible populations.

Metabolic dormancy in Chlamydia trachomatis treated with different antibiotics.

Diseases caused by Chlamydia spp. are often associated with persistent infections. Chlamydial persistence is commonly associated with a unique non-infectious intracellular developmental form, termed an aberrant form. Although infectious chlamydiae can be cultured consistently in cells stressed to aberrancy, their role in persistence is not clear. Recovery from antibiotic stress was explored as a model to determine how survival of non-aberrant chlamydiae, in the presence of fully inhibitory drug concentrations, may participate in persistence. Assays included incubation in quinolones, tetracyclines, or chloramphenicol for differing lengths of time, followed by an extended recovery period in antibiotic-free media. Culturable elementary bodies were not detected during treatment with each antibiotic, but viable and culturable Chlamydia trachomatis emerged after the drug was removed. Time-lapse imaging of live, antibiotic-treated infected cells identified metabolically dormant developmental forms within cells that emerged to form typical productive inclusions. The effects of the increasing concentration of most tested antibiotics led to predictable inhibitory activity, in which the survival rate decreased with increasing drug concentration. In contrast, in fluoroquinolone-treated cells, there was a paradoxical increase in productive development that was directly correlated with drug concentration and inversely associated with aberrant form production. This model system uncovers a unique chlamydial persistence pathway that does not involve the chlamydial aberrant form. The association between productive latency and metabolic dormancy is consistent with models for many bacterial species and may lead to a different interpretation of mechanisms of chlamydial persistence in patients.IMPORTANCEThe life history of most pathogens within the genus Chlamydia relies on lengthy persistence in the host. The most generally accepted model for Chlamydia spp. persistence involves an unusual developmental stage, termed the aberrant form, which arises during conditions that mimic a stressful host environment. In this work, we provide an alternate model for chlamydial persistence in the face of antibiotic stress. This model may be relevant to antibiotic treatment failures in patients infected with C. trachomatis.

Synthesis of Titanate Nanotube for Antibacterial and Tissue Regeneration Applications

An increasingly crucial therapeutic issue revolves around treating bacterial infections in chronic skin wounds that have developed resistance to antibiotics. Despite the current advancements in diagnosis, a significant number of patients still experience therapeutic failure of anti-microbials or antibiotic treatments. In this study, sodium titanate nanotubes (Na-TiNTs) were synthesized via a straightforward hydrothermal approach to facilitate the immobilization of Gentamicin (Gn) and Phenytoin (PhT). The samples were extensively characterized using different techniques, including XRD, FTIR, SEM/EDX, TEM, TGA, and BET. The result reveals that synthesized Na-TiNTs are highly porous rods in shape, with an internal diameter of 5 nm and an outer diameter ranging from 10 to 15 nm. After 16 h of encapsulation, Gn had an encapsulation efficiency (EE%) of 80 ± 2.3 %, while PhT had 89.0 ± 3.1 %. Also, Gn and PhT were released linearly, reaching 95.3 ± 1.6 % and 97.3 ± 1.6 % after 96 h. The highest doses of Gn/Na-TiNTs and PhT/Na-TiNTs, about 500 mg/mL, reduced the cell viability value from 98.2 ± 2.2 % for the untreated cell to 85.1 ± 1.6 % and 88.3 ± 3.4 %, respectively. In addition, PhT/Na-TiNTs ZOI was 28.1 ± 2.3 and 30.1 ± 1.7 mm, andthe ZOI of Gn/Na-TiNTs was 39.0 ± 1.6 mm 45.0 ± 2.4 mm for S. aureus and E. coli, indicating that PhT had antibacterial potency comparable to the standard antibiotic but less than Gn/Na-TiNTs. In vitro wound closure of approximately 87 % for Gn/Na-TiNTs and exhibited a 95 % for PhT/Na-TiNTs after 72 h. The initial findings indicate that Gn/Na-TiNTs and PhT/Na-TiNTs exhibit a sustained drug release profile, which holds potential as a viable strategy for enhancing the antibacterial efficacy and promotewound healing.

Streptococcus pneumoniae favors tolerance via metabolic adaptation over resistance to circumvent fluoroquinolones.

Streptococcus pneumoniae is a major human pathogen of global health concern and the rapid emergence of antibiotic resistance poses a serious public health problem worldwide. Fluoroquinolone resistance in S. pneumoniae is an intriguing case because the prevalence of fluoroquinolone resistance does not correlate with increasing usage and has remained rare. Our data indicate that deleterious fitness costs in the mammalian host constrain the emergence of fluoroquinolone resistance both by de novo mutation and recombination. S. pneumoniae was able to circumvent such deleterious fitness costs via the development of antibiotic tolerance through metabolic adaptation that reduced the production of reactive oxygen species, resulting in a fitness benefit during infection of mice treated with fluoroquinolones. These data suggest that the emergence of fluoroquinolone resistance is tightly constrained in S. pneumoniae by fitness tradeoffs and that mutational pathways involving metabolic networks to enable tolerance phenotypes are an important contributor to the evasion of antibiotic-mediated killing.IMPORTANCEThe increasing prevalence of antibiotic resistant bacteria is a major global health concern. While many species have the potential to develop antibiotic resistance, understanding the barriers to resistance emergence in the clinic remains poorly understood. A prime example of this is fluroquinolone resistance in Streptococcus pneumoniae, whereby, despite continued utilization, resistance to this class of antibiotic remains rare. In this study, we found that the predominant pathways for developing resistance to this antibiotic class severely compromised the infectious capacity of the pneumococcus, providing a key impediment for the emergence of resistance. Using in vivo models of experimental evolution, we found that S. pneumoniae responds to repeated fluoroquinolone exposure by modulating key metabolic pathways involved in the generation of redox molecules, which leads to antibiotic treatment failure in the absence of appreciable shifts in resistance levels. These data underscore the complex pathways available to pathogens to evade antibiotic mediating killing via antibiotic tolerance.

Cymbopogon citratus L. essential oil as a potential anti-biofilm agent active against antibiotic-resistant bacteria isolated from chronic rhinosinusitis patients

Chronic rhinosinusitis (CRS) is long-term inflammation of the sinuses that can be caused by infection due to antibiotic-resistant bacteria. Biofilm developed by microbes is postulated to cause antibiotic treatment failure. Thus, the anti-biofilm activities of seven Thai herbal essential oils (EOs) against antibiotic-resistant bacteria isolated from CRS patients was investigated. Lemongrass (Cymbopogon citratus L.) EO showed the most effective antibiofilm activity against Klebsiella pneumoniae, Pseudomonas aeruginosa and Staphylococcus epidermidis grown as biofilm. GC-MS analysis found that myrcene was the major bioactive compound. Pretreatment with lemongrass EO significantly inhibited biofilm formation of all bacterial strains in more than 50% of cases. Furthermore, confocal microscopy analysis revealed the biofilm-disrupting activity of lemongrass EO against the biofilm matrix of all these bacterial species and also increased P. aeruginosa swarming motility with no toxicity to human cells. These results suggest that lemongrass EO has promising clinical applications as an anti-biofilm agent for CRS patients.

Pulmonary extranodal natural killer/T-cell lymphoma: clinical presentation, CT characteristics, and patient outcomes.

Due to the extreme rarity of pulmonary extranodal natural killer/T-cell lymphoma (ENKTCL), studies on this lymphoma type are limited. We aimed to investigate the clinical presentations, computed tomography (CT) findings, CT dynamic changes, and outcomes of patients diagnosed with pulmonary ENKTCL. We conducted a retrospective cohort study on ENKTCL, nasal type, at West China Hospital, from January 2010 to January 2023. Out of 27 initial cases with pulmonary ENKTCL, we excluded 4 due to the lack of chest CT images, resulting in a final cohort of 23 patients. Our evaluation covered clinical features, laboratory findings, CT presentations, treatment strategies, and survival outcomes. Survival analyses were performed using the Kaplan-Meier method, with log-rank tests for survival curve comparisons. Given the small sample size, our interpretation of the data is mainly descriptive. The most common CT presentations in our institution was solitary or multiple nodules (7/23, 30.4%). The halo sign (78.3%) and floating vessels sign (83.3%) were commonly observed in pulmonary ENKTCL. Elevated lactate dehydrogenase (LDH) levels were observed in 20 (86.9%) patients. The median overall survival (OS) for pulmonary ENKTCL patients was 1 month; 3 cases displayed a favorable prognosis, maintaining complete remission (CR) status for 1.5-7 years after receiving chemotherapy. Chemotherapy led to improved prognosis, with a median survival of 5 months seen in patients who received chemotherapy. Patients with bilateral lung involvement had worse outcomes compared to those with unilateral lesions. Pulmonary ENKTCL is a rare and aggressive disease, often misdiagnosed due to nonspecific clinical and CT features. Laboratory tests, failure of antibiotic treatment, and "floating vessels sign" on enhanced CT scans may aid in diagnosis. Timely chemotherapy may improve survival, emphasizing the importance of early detection and prompt treatment.

2839. Cost Burden of Patients with Oral Antibiotic Treatment Failure for Uncomplicated Urinary Tract Infection in the United States

Abstract Background Urinary tract infections (UTIs) are the most common bacterial infections in women. Antibiotics (ABX) are available to treat uncomplicated UTI (uUTI), but 10–30% of patients experience treatment failure (TF). We assessed uUTI-related healthcare costs among uUTI patients with/without oral ABX TF in the United States (US). Methods This retrospective cohort study used Optum’s de-identified Clinformatics Data Mart Database from October 1, 2015 to September 30, 2021 (Figure 1). Eligible patients were female, ≥ 18 years, with a uUTI diagnosis identified in an outpatient setting, ≥ 1 oral ABX prescription within ± 5 days of diagnosis, and ≥ 1 year pre- and post-index follow-up. ABX prescription claim was designated index date. uUTI-related costs were compared for patients with and without TF. TF was defined as any of the following during the initial uUTI episode (≤ 28 days post-index): ≥ 1 additional oral ABX prescription(s); intravenous ABX; or a primary diagnosis of UTI in an acute care setting (emergency room or inpatient). uUTI-related costs (US$) were assessed during the follow-up period. Results In total, 238,335 patients were identified, of whom 29,333 (12.3%) had evidence of TF. Total uUTI-related costs were higher for patients with TF vs those without (mean [standard deviation, SD] $1133 [$5023] vs $276 [$1582]; p &amp;lt; 0.0001; [Figure 2]). uUTI-related outpatient costs were higher for patients with vs without TF (mean [SD] $808 [$3368] vs $238 [$838]; p &amp;lt; 0.0001). Patients with TF had higher outpatient costs across all categories, with outpatient hospital visits contributing 45.6% of costs (Figure 3). By contrast, outpatient hospital visits accounted for &amp;lt; 20% of all outpatient costs for patients without TF; in these patients, office costs were the greatest contributor (31.9%). uUTI-related inpatient costs were higher for patients with TF vs those without (mean [SD] $297 [$3562] vs $25 [$1326]; p &amp;lt; 0.0001). Mean (SD) pharmacy costs for patients with vs without TF were $28 ($26) and $13 ($16), respectively (p &amp;lt; 0.0001). Figure 1. Study design ABX, antibiotic; HCRU, healthcare resource use; rUTI, recurrent urinary tract infection; uUTI, uncomplicated urinary tract infection; Rx, prescription. Conclusion Patients with ABX TF for uUTI had significantly higher costs (inpatient, outpatient, and pharmacy) than patients without TF. This finding highlights the importance of appropriate empiric ABX selection to reduce the likelihood of TF in uUTI and its economic impact.Figure 2.Mean uUTI-related costs during the follow-up period. All differences (patients with versus without treatment failure) were significant (p&amp;lt;0.0001). Outpatient costs = emergency room costs, outpatient hospital visits costs, office visits costs, lab and radiology tests costs, home health costs, durable medical equipment costs, and other outpatient costs. TF, treatment failure; uUTI, uncomplicated urinary tract infection.Figure 3.Distribution of uUTI-related outpatient costs in patients with versus without TF. Costs are in USD. Other costs = home health costs, durable medical equipment costs, and other outpatient costs. ER, emergency room; TF, treatment failure; USD, united states dollars; uUTI, uncomplicated urinary tract infection. Disclosures Meg Franklin, PharmaD, PhD, Franklin Pharmaceutical Consulting: Owner and President|Franklin Pharmaceutical Consulting: Ownership Interest|GSK: Grant/Research Support|PRECISIONheor: Contractor Maia R. Emden, BA, GSK: Grant/Research Support|PRECISIONheor: Employee Sharon Kautz, BS, GSK: Grant/Research Support|PRECISIONheor: Employee Anh Thy H. Nguyen, MSPH, GSK: Grant/Research Support|PRECISIONheor: Employee Naomi C. Sacks, PhD, GSK: Grant/Research Support|PRECISIONheor: Employee Shinyoung Ju, MS, GSK: Employee|GSK: Stocks/Bonds Fanny S. Mitrani-Gold, MPH, GSK: Employee|GSK: Stocks/Bonds Ashish V. Joshi, PhD, GSK: Employee|GSK: Stocks/Bonds Madison T. Preib, MPH, GSK: Employee|GSK: Stocks/Bonds

Bacterial heterogeneity and antibiotic persistence: bacterial mechanisms utilized in the host environment.

SUMMARYAntibiotic persistence, or the ability of small subsets of bacteria to survive prolonged antibiotic treatment, is an underappreciated cause of antibiotic treatment failure. Over the past decade, researchers have discovered multiple different stress responses and mechanisms that can promote antibiotic persistence. However, many of these studies have been completed in culture-based systems that fail to truly replicate the complexities of the host environment, and it is unclear whether the mechanisms defined in in vitro studies are applicable during host infection. In this review, we focus our discussion on recent studies that utilize a mixture of ex vivo culture systems and animal models to understand what stressors in the host environment are important for inducing antibiotic persistence. Different host stressors are involved depending on the anatomical niche the bacteria reside in and whether the host immune system is primed to generate a more robust response against bacteria, which can result in differing downstream effects on antibiotic susceptibility. Bacterial pathogens can also utilize specific strategies to reprogram their metabolism, which is vital for transitioning into an antibiotic-persistent state within host tissues. Importantly, we highlight that more attention is needed to establish guidelines for in vivo work on antibiotic persistence, particularly when identifying antibiotic-persistent subpopulations and distinguishing these phenotypes from antibiotic tolerance. Studying antibiotic persistence in the context of the host environment will be crucial for developing tools and strategies to target antibiotic-persistent bacteria and increase the efficacy of antibiotic treatment.

Treatment of postpartum endometritis induced by multidrug-resistant bacterial infection in dairy cattle by green synthesized zinc oxide nanoparticles and in vivo evaluation of its broad spectrum antimicrobial activity in cow uteri

Postpartum endometritis significantly affects the health and productivity of cattle, causing significant economic loss that is speculated to exceed billions of dollars annually. Treatment of postpartum endometritis, which is linked to various bacterial infections in the uterus after delivery and has an alarmingly high risk of antibiotic treatment failure for unidentified reasons, represents a great challenge. Several studies have demonstrated that various disease complications, such as multidrug-resistant (MDR) bacterial strains, prolonged infection treatment, and increased mortality risk, have emerged as a result of the extensive use of antibiotics to treat uterine infections and other microbial-related diseases. Recent research has led to the development of zinc oxide nanoparticles (ZnO NPs) that exhibit broad-spectrum antibacterial efficacy against bacterial pathogens, including MDR bacteria, without producing mutants that are resistant to zinc oxide (ZnO). In the present work, we biologically synthesized ZnO NPs from a green natural source of Helianthus annuus seeds for the treatment of endometritis caused by MDR bacterial strains in dairy cattle. We examined ZnO's potential as a substitute antimicrobial agent to treat cow endometritis by testing its ability to sustain potent antimicrobial activity against pathogenic bacteria, including Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), in cow uteri. Among uterine bacteria, ZnO significantly decreased E. coli and S. aureus, which are known pathogenic bacteria within the uterus and achieved a high cure rate that was associated with the induction of estrous and pregnancy. Taken together, our observations of ZnO's broad range of antibacterial activity in-vivo with an animal model and subsequent evaluations of its therapeutic efficacy in cows with endometritis shed light on its potential to be used as a substitute antimicrobial agent for the treatment of uterine illness.

Ongoing diversification of the global fish pathogen Piscirickettsia salmonis through genetic isolation and transposition bursts

The management of bacterial pathogens remains a key challenge of aquaculture. The marine gammaproteobacterium Piscirickettsia salmonis is the etiological agent of piscirickettsiosis and causes multi-systemic infections in different salmon species, resulting in considerable mortality and substantial commercial losses. Here, we elucidate its global diversity, evolution, and selection during human interventions. Our comprehensive analysis of 73 closed, high quality genome sequences covered strains from major outbreaks and was supplemented by an analysis of all P. salmonis 16S rRNA gene sequences and metagenomic reads available in public databases. Genome comparison showed that Piscirickettsia comprises at least three distinct, genetically isolated species of which two showed evidence for continuing speciation. However, at least twice the number of species exist in marine fish or seawater. A hallmark of Piscirickettsia diversification is the unprecedented amount and diversity of transposases which are particularly active in subgroups undergoing rapid speciation and are key to the acquisition of novel genes and to pseudogenization. Several group-specific genes are involved in surface antigen synthesis and may explain the differences in virulence between strains. However, the frequent failure of antibiotic treatment of piscirickettsiosis outbreaks cannot be explained by horizontal acquisition of resistance genes which so far occurred only very rarely. Besides revealing a dynamic diversification of an important pathogen, our study also provides the data for improving its surveillance, predicting the emergence of novel lineages, and adapting aquaculture management, and thereby contributes towards the sustainability of salmon farming.

Pseudomonas aeruginosa Soluble Pyocins as Antibacterial Weapons.

Pseudomonas aeruginosa is an opportunistic pathogen causing nosocomial infections and associated with lung infections in cystic fibrosis (CF) patients (Lyczak et al., Microbes Infect 2:1051-1060, 2000). Multiple drug-resistant P. aeruginosa strains pose a serious problem because of antibiotic treatment failure. There is therefore a need for alternative anti-Pseudomonas molecules. Soluble pyocins (S-pyocins) are bacteriocins produced by P. aeruginosa strains that kill sensitive strains of the same species. These bacteriocins and their immunity gene are easily cloned and expressed in E. coli and their activity spectrum against different P. aeruginosa strains can be tested. In this chapter, we describe the procedures for cloning, expression, and sensitivity testing of two different S-pyocins. We also describe how to identify their receptor binding domain in sensitive strains, how to construct chimeric pyocins with extended activity spectra, and how to identify new pyocins in genomes by multiplex PCR.