Impact of Implementing an Antimicrobial Stewardship Program for Optimizing Antibiotic Treatment in Gram-negative Bacilli Bacteremia.

BACKGROUND: Antibiotic Stewardship Programs (ASP) have improved empirical and directed antibiotic treatment in Gram-negative bloodstream infections. A decrease in mortality, readmission, and length of hospitalization has been reported. MATERIALS AND METHODS: A pre-post-quasi-experimental study was conducted between November and April 2015-2016 (pre-intervention period), 2016-2017, 2017-2018, and 2018-2019 (post-intervention periods), to analyse the impact of ASP on empirical, directed, and entire treatment optimization, as well as mortality, readmission, and length of hospitalization, in hospitalized patients with Gram-negative bacilli (GNB) bloodstream infections. RESULTS: One hundred seventy-four patients were included (41 in the pre-intervention group, 38 in the first-year post-intervention group, 50 in the second-year post-intervention group, and 45 in the third-year post-intervention group). There was a significant improvement in directed treatment optimization (43.9% in the pre-intervention group, 68.4% in the first-year post-intervention group, 74% in the second-year post-intervention group, and 88.9% in the third-year post-intervention group, P <0.001), as well as in entire treatment optimization (19.5%, 34.2%, 40.0%, and 46.7%, respectively, P=0.013), with increased optimal directed (adjusted odds ratio [aOR], 3.71; 95% confidence interval [CI], 1.60-8.58) and entire treatment (aOR, 3.31; 95% CI, 1.27-8.58). Although a tendency toward improvement was observed in empirical treatment after ASP implementation, it did not reach statistical significance (41.5% vs. 57.9%, P=0.065). No changes in mortality, readmission, or length of hospitalization were detected. CONCLUSION: ASP implementation improved both directed and entire treatment optimization in patients with GNB bloodstream infections over time. Nevertheless, no improvement was found in clinical outcomes such as mortality, readmission, or length of hospitalization.

Effect of multifunctional cationic polymer coatings on mitigation of broad microbial pathogens.

Infection control measures to prevent viral and bacterial infection spread are critical to maintaining a healthy environment. Pathogens such as viruses and pyogenic bacteria can cause infectious complications. Viruses such as SARS-CoV-2 are known to spread through the aerosol route and on fomite surfaces, lasting for a prolonged time in the environment. Developing technologies to mitigate the spread of pathogens through airborne routes and on surfaces is critical, especially for patients at high risk for infectious complications. Multifunctional coatings with a broad capacity to bind pathogens that result in inactivation can disrupt infectious spread through aerosol and inanimate surface spread. This study uses C-POLAR, a proprietary cationic, polyamine, organic polymer with a charged, dielectric property coated onto air filtration material and textiles. Using both SARS-CoV-2 live viral particles and bovine coronavirus models, C-POLAR-treated material shows a dramatic 2-log reduction in circulating viral inoculum. This reduction is consistent in a static room model, indicating simple airflow through a static C-POLAR hanging can capture significant airborne particles. Finally, Gram-positive and Gram-negative bacteria are applied to C-POLAR textiles using a viability indicator to demonstrate eradication on fomite surfaces. These data suggest that a cationic polymer surface can capture and eradicate human pathogens, potentially interrupting the infectious spread for a more resilient environment. IMPORTANCE: Infection control is critical for maintaining a healthy home, work, and hospital environment. We test a cationic polymer capable of capturing and eradicating viral and bacterial pathogens by applying the polymer to the air filtration material and textiles. The data suggest that the simple addition of cationic material can result in the improvement of an infectious resilient environment against viral and bacterial pathogens.

Use of Synchrotron Radiation Circular Dichroism to Analyze the Interaction and Insertion of Proteins into Bacterial Outer Membrane Vesicles.

Circular dichroism (CD) is a spectroscopic technique commonly used for the analysis of proteins. Particularly, it allows the determination of protein secondary structure content in various media, including the membrane environment. In this chapter, we present how CD applications can be used to analyze the interaction of proteins with bacterial outer membrane vesicles (OMVs). Most CD studies characterizing the structure of proteins inserted into membranes rely on artificial lipid bilayers, mimicking natural membranes. Nevertheless, these artificial models lack the important features of the true membrane, especially for the outer membrane of Gram-negative bacteria. These features include lipid diversity, glycosylation, and asymmetry. Here, we show how to analyze the interactions of proteins, either integral or peripheral, with OMVs in solution and with supported membranes of OMVs, using conventional CD and orientated circular dichroism (OCD). We explain how to decipher the spectroscopic signals to obtain information on the molecular structure of the protein upon its interaction with an OMV and through its potential insertion into an OMV membrane.

Cubosome lipid nanocarriers for delivery of ultra-short antimicrobial peptides.

HYPOTHESIS: Although antimicrobial peptides (AMPs) are a promising class of new antibiotics, their inherent susceptibility to degradation requires nanocarrier-mediated delivery. While cubosome nanocarriers have been extensively studied for delivery of AMPs, we do not currently understand why cubosome encapsulation improves antimicrobial efficacy for some compounds but not others. This study therefore aims to investigate the link between the mechanism of action and permeation efficiency of the peptides, their encapsulation efficacy, and the antimicrobial activity of these systems. EXPERIMENTS: Encapsulation and delivery of Indolicidin, and its ultra-short derivative, Priscilicidin, were investigated using SAXS, cryo-TEM and circular dichroism. Molecular dynamics simulations were used to understand the loading of these peptides within cubosomes. The antimicrobial efficacy was assessed against gram-negative (E. coli) and gram-positive (MRSA) bacteria. FINDINGS: A high ionic strength solution was required to facilitate high loading of the cationic AMPs, with bilayer encapsulation driven by tryptophan and Fmoc moieties. Cubosome encapsulation did not improve the antimicrobial efficacy of the AMPs consistent with their high permeation, as explained by a recent 'diffusion to capture model'. This suggests that cubosome encapsulation may not be an effective strategy for all antimicrobial compounds, paving the way for improved selection of nanocarriers for AMPs, and other antimicrobial compounds.

Evaluation of the efficiency of various methods to load fluoroquinolones into Escherichia coli outer membrane vesicles as a novel antibiotic delivery platform.

The development of novel antibacterial agents that are effective against Gram-negative bacteria is limited primarily by transport issues. This class of bacteria maintains a complex cell envelope consisting of two membrane bilayers, preventing the passage of most antibiotics. These drugs must therefore pass through protein channels called porins; however, many antibiotics are too large to pass through porins, and a common mechanism of acquired resistance is down-regulation of porins. To overcome this transport limitation, we have proposed the use of outer membrane vesicles (OMVs), released by Gram-negative bacteria, which deliver cargo to other bacterial cells in a porin-independent manner. In this work, we systematically studied the ability to load fluoroquinolones into purified Escherichia coli OMVs using in vivo and in vitro passive loading methods, and active loading methods such as electroporation and sonication. We observed limited loading of all of the antibiotics using passive loading techniques; sonication and electroporation significantly increased the loading, with electroporation at low voltages (200 and 400V) resulting in the greatest encapsulation efficiencies. We also demonstrated that imipenem, a carbapenem antibiotic, can be readily loaded into OMVs, and its administration via OMVs increases the effectiveness of the drug against E. coli. Our results demonstrate that small molecule antibiotics can be readily incorporated into OMVs to create novel delivery vehicles to improve antibiotic activity.

Challenges and Trends in Gram-Negative Bacterial Infections in Critically Neonates: A Seven-and-a-Half-Year Observational Study.

OBJECTIVE: Analyze the incidence, risk factors, and fatality rates of bloodstream infections by Gram-negative bacteria (GNB-BSIs) in a Neonatal Intensive Care Unit (NICU). METHODS: This study employs a retrospective cohort design utilizing records of neonates admitted to the NICU between January 2015 and June 2022. RESULTS: Among 1,495 neonates, 5.2% developed GNB-BSIs. The average incidence of infection/1,000 patient-days was 2.9. Primary risk factors for infection included preceeding carbapenem use were significant risk factors (OR=514.4; P<0.01) and 4th generation cephalosporins (OR=66; P<0.01). Among the 85 GNB, 75.3% were fermenters, and 24.7% were non-fermenters. Of the isolates, 14.1% produced extended-spectrum beta-lactamase, and 2.3% carbapenem resistant. Infection correlated with prolonged hospital stays (10 to 39 days) and increased mortality (10% to 29.9%). CONCLUSION: The high incidence of GNB-BSIs was exacerbated by the preceeding use of broad-spectrum antimicrobials, increasing the presence of multidrug-resistant isolates and fatality rates. These findings emphasize the importance of active surveillance.

Synergism of colistin and globular endolysins against multidrug-resistant gram-negative bacteria.

Endolysins (lysins), a novel class of antibacterial agents derived from bacteriophages, efficiently lyse bacteria by degrading the peptidoglycan layer within the bacterial wall. Colistin, a classic peptide antibiotic with the ability to permeabilize the outer membrane, has recently shown great promise in synergizing with lysins against gram-negative bacteria. However, the exact mechanism responsible for their synergy remains unclear. Here, we first demonstrated the synergistic bacterial killing of various lysin and colistin combinations. With a model lysin, LysAB2, we then confirmed that there is a threshold concentration of colistin causing sufficient permeabilization of the outer membrane for lysin to access the peptidoglycan layer and subsequently exert its lytic ability. The threshold colistin concentrations were found to range 0.2-0.8 µM for the tested bacteria, with the exact value largely depending on the density of lipopolysaccharides on the outer membrane. Beyond the threshold colistin level, LysAB2 could synergize with colistin at a concentration as low as 0.31 µM. Next, we proved for the first time that lysin-induced degradation of the peptidoglycan layer facilitated the disruption of cytoplasmic membrane by colistin, elevated the level of reactive oxygen species in bacterial cells, and boosted the killing effect of colistin. Additionally, the colistin-lysin combination could effectively eliminate established biofilms due to the biofilm dispersal ability of lysin. The in-vivo efficacy was preliminary confirmed in a Galleria mellonella infection model for combination with colistin doses (≥ 1.8 µg/larvae), which could reach beyond the threshold concentration, and a fixed LysAB2 dose (10 µg/larvae). In summary, our study provided the first experimental evidence unravelling the mechanisms behind the synergy of colistin and lysins. All these findings provided important insights in guiding the dosing strategy for applying this combination in future development.

Mystery of the Passerini Reaction for the Synthesis of the Antimicrobial Peptidomimetics against Nosocomial Pathogenic Bacteria.

The first example of applying salicylaldehyde derivatives, as well as coumarin with the formyl group at the C8 position in its structure, as carbonyl partners in a three-component Passerini reaction, is presented. As a result of research on the conditions of the Passerini reaction, the important role of the hydroxyl group in the salicylaldehyde used in the course of the multicomponent reaction was revealed. When an aldehyde with an unprotected hydroxyl group is used, only two-component α-hydroxy amide products are obtained. In contrast, the use of acylated aldehyde results in three-component α-acyloxy amide products with high efficiency. The developed protocol gives access to structurally diversified peptidomimetics with good yield. The compounds were also evaluated as antimicrobial agents against selected strains of nosocomial pathogenic bacteria. The structure-activity relationship revealed that inhibitory activity is strongly related to the presence of the trifluoromethyl group (CF3) or the methyl group at the C4 position in an unsaturated lactone ring of the coumarin scaffold. MIC and MBC studies were carried out on eight selected pathogenic bacteria strains (Gram-positive pathogenic Staphylococcus aureus strain (ATCC 23235), as well as on Gram-negative E. coli (K12 (ATCC 25404), R2 (ATCC 39544), R3 (ATCC 11775), and R4 (ATCC 39543)), Acinetobacter baumannii (ATCC 17978), Pseudomonas aeruginosa (ATCC 15442), and Enterobacter cloacae (ATCC 49141) have shown that the tested compounds show a strong bactericidal effect at low concentrations. Among all agents investigated, five exhibit higher antimicrobial activity than those observed for commonly used antibiotics. It should be noted that all the compounds tested showed very high activity against S. aureus, which is the main source of nosocomial infections that cause numerous fatalities. Additionally, the cytotoxicity of sixteen derivatives was measured with the use of the MTT test on BALB/c3T3 mouse fibroblast cell lines. The cytotoxicity studies revealed that the tested substances exert a similar or lower effect on cell proliferation than that observed for commonly used antibiotics within the range of therapeutic doses. A parallel MTT assay using ciprofloxacin, bleomycin, and cloxacillin showed that these antibiotics are more cytotoxic when tested in mammalian cells, and cell viability is in the range of 85.0-89.9%. Furthermore, we have shown that the studied coumarin-based peptidomimetics, depending on their structural characteristics, are nonselective and act efficiently against various Gram-positive and Gram-negative pathogens, which is of great importance for hospitalised patients.

Role of Small Non-Coding RNA in Gram-Negative Bacteria: New Insights and Comprehensive Review of Mechanisms, Functions, and Potential Applications.

Small non-coding RNAs (sRNAs) are a key part of gene expression regulation in bacteria. Many physiologic activities like adaptation to environmental stresses, antibiotic resistance, quorum sensing, and modulation of the host immune response are regulated directly or indirectly by sRNAs in Gram-negative bacteria. Therefore, sRNAs can be considered as potentially useful therapeutic options. They have opened promising perspectives in the field of diagnosis of pathogens and treatment of infections caused by antibiotic-resistant organisms. Identification of sRNAs can be executed by sequence and expression-based methods. Despite the valuable progress in the last two decades, and discovery of new sRNAs, their exact role in biological pathways especially in co-operation with other biomolecules involved in gene expression regulation such as RNA-binding proteins (RBPs), riboswitches, and other sRNAs needs further investigation. Although the numerous RNA databases are available, including 59 databases used by RNAcentral, there remains a significant gap in the absence of a comprehensive and professional database that categorizes experimentally validated sRNAs in Gram-negative pathogens. Here, we review the present knowledge about most recent and important sRNAs and their regulatory mechanism, strengths and weaknesses of current methods of sRNAs identification. Also, we try to demonstrate the potential applications and new insights of sRNAs for future studies.

Ceftolozane/Tazobactam for the Treatment of Adults With Cystic Fibrosis: Results From a French Prospective Cohort Study.

Background: People with cystic fibrosis (pwCF) are particularly susceptible to respiratory infections, including those caused by multidrug-resistant (MDR) pathogens. Ceftolozane/tazobactam (C/T) is an antibacterial agent combination active against MDR gram-negative bacteria that has shown promising results in isolates from pwCF. This subanalysis is the first extensive observation of real-world C/T use in pwCF. Methods: The multicenter observational CONDUCT study included consecutive patients, some with cystic fibrosis, who received ≥1 dose of C/T at 28 centers throughout France. Patients were treated according to hospital standards and followed up until the end of C/T treatment (EOT). Results: Among 260 patients who had received ≥1 dose of C/T, 63 were pwCF, including 12 with previous lung transplant. The median age was 34 years and 55.6% of patients were female. Pseudomonas aeruginosa was the most frequently isolated pathogen (n = 40/41 [97.6%]). Most tested P aeruginosa strains (n = 65/73 [91.5%]) and all other isolated strains (Escherichia coli, Citrobacter koseri, Proteus mirabilis, and Serratia marcescens) were susceptible to C/T. Most patients completed the treatment duration, including those with historical ß-lactam hypersensitivity. Reasons for stopping treatment were planned EOT and improvement in condition; overall, 88.9% of patients (n = 56/63) experienced improvement in condition. No new safety signals were identified. Mean forced expiratory volume in 1 second improved from 1.33 L to 1.47 L before and after C/T treatment, respectively (n = 52; P = .057). Conclusions: C/T treatment was well tolerated and effective in pwCF, including those with previous ß-lactam hypersensitivity.

Ceftazidime-Avibactam as a Salvage Treatment for Severely Infected Immunosuppressed Children.

Background: Multidrug-resistant Gram-negative bacteria (MDR-GNB) are becoming increasingly common around the world, with carbapenems frequently serving as a last resort but being threatened by the growing incidence of carbapenemase-producing bacteria. Ceftazidime-avibactam (CAZ/AVI) is a potential agent against MDR-GNB but with limited clinical experience, particularly in critically ill immunosuppressed children. Methods: This study analyzed the use of CAZ/AVI as salvage treatment in severely infected immunosuppressed children from September 2019 to July 2022. Patients with confirmed GNB infection who received CAZ/AVI were matched with patients who received other antibiotics. Results: Twenty-five critically ill immunosuppressed children treated with CAZ/AVI were included. The majority had hematologic diseases. All patients presented with sepsis in all 30 courses. Septic shock presented in 36.7% of these courses. The primary sites of infection included bloodstream infection (20.0%), skin and skin structure infection (20.0%), intra-abdominal infection (13.3%) and hospital-acquired pneumonia (10.0%). Twelve of the 25 (48.0%) patients had positive microbiological cultures, mainly Pseudomonas aeruginosa and Klebsiella pneumoniae, including 5 carbapenem-resistant GNB-infected cases. Fifteen (50.0%) courses presented clinical improvement. For the initial course of each patient, the clinical response rate of the GNB recovered group was significantly higher than that of the group without GNB recovery (66.7% vs 23.1%, P = 0.047). The 14-day and 30-day mortality rates were 24.0% and 28.0%, respectively, which were significantly correlated with the absence of GNB recovery (P = 0.004 and 0.024, respectively) and hospital-acquired pneumonia as the primary site of infection (P = 0.001 and 0.006, respectively). There was no significant difference in major outcomes between patients who received CAZ/AVI and matched patients who received other antibiotics. Conclusion: CAZ/AVI could be considered a salvage strategy for immunosuppressed children with confirmed GNB infection. Caution should be taken when CAZ/AVI is applied to these patients in the absence of GNB recovery.

Impact of the COVID-19 pandemic on the incidence and the epidemiology of catheter-related bloodstream infection two years later.

Introduction: The COVID-19 pandemic increased catheter-related bloodstream infections (C-RBSI), but its subsequent impact has not been adequately described. Our hospital has already depicted the effects of the COVID-19 pandemic in the first wave. However, we still do not know whether C-RBSI rates and aetiology are similar to those described before the COVID-19 pandemic. We aimed to evaluate the impact of the COVID-19 pandemic on the evolution of C-RBSI in a large tertiary teaching hospital two years later. Material and methods: We prospectively collected all confirmed C-RBSI episodes in a clinical microbiology laboratory database by matching blood cultures and catheter tip cultures with the isolation of the same microorganism (s). We compared our C-RBSI incidence rates and aetiology from 2018 to 2023. C-RBSI was defined as bacteremia or fungemia in a patient with clinical manifestations of infection and no other apparent source except the catheter. Results: During the study period, we collected 556 C-RBSI episodes. C-RBSI incidence rate per 1000 admissions each year was as follows: 2018: 2.2; 2019: 1.7; 2020: 3.29; 2021: 2.92; 2022: 2.69. and 2023: 2.01. Mainly, C-RBSI episodes occurring in critical care units each year were, respectively: 2018: 57 (54.8 %), 2019: 38 (45.2 %), 2020: 89 (63.6 %), 2021: 69 (60.5 %), 2022: 58 (50.9 %) and 2023 (61.4 %). The distribution of microorganisms showed an increase in Gram-negative episodes after the pandemic. Conclusion: Our study shows an increase in the incidence rate of C-RBSI during the COVID-19 pandemic, with a discrete decrease after that. C-RBSI episodes were mainly caused by coagulase-negative Staphylococci but with a rise in Gram-negative bacilli.

An Update on Colistin in Clinical Healthcare Unit in the Kingdom of Saudi Arabia: A Narrative Review.

Globally, gram-negative bacteria are a significant cause of morbidity. Multi-drug resistance bacteria are responsible for an increasing surge in infections that place a high cost on healthcare systems around the world. Recently, colistin, an antibiotic belonging to the polymyxin family, was reintroduced to combat multidrug- resistant gram-negative bacteria. Excessive and persistent use of colistin has led to the development and spread of colistin-resistant gram-negative bacteria throughout the globe. Healthcare units in various countries, including Saudi Arabia, are currently battling colistin-resistant gram-negative bacteria. Recently, colistin-resistant gram-negative bacteria have become a major health concern in Saudi Arabia. Hence, extensive epidemiological surveys and studies are required to understand the current status of the colistin antibiotic. Examining the knowledge currently available to the medical community on the molecular mechanism, clinical effectiveness, molecular epidemiology, and bacterial resistance to colistin in Saudi Arabia is the aim of this review.

Is there evidence on the optimal duration of aminoglycoside therapy in beta-lactam/aminoglycoside combination regimens used for the treatment of Gram-negative bacterial infections? -A Systematic Review.

BACKGROUND: The optimal duration of therapy of aminoglycosides in combination regimens is expected to be different to monotherapy regimens; and shorter durations could help minimize toxicity without compromising efficacy. The aim of this review was to assess the evidence for the optimal duration of aminoglycosides in beta-lactam/aminoglycoside combinations used for the treatment of Gram-negative bacterial infections. METHODS: PubMed, Cochrane, Embase, Scopus, Web of Science, and CINHAL databases were searched. Covidence software was used for article screening and management. Studies were included if they clearly reported the duration of therapy of aminoglycosides in beta-lactam/aminoglycoside combinations used against Gram-negative bacteria. The protocol is registered with PROSPERO (CRD42023392709). RESULTS: A total of 45 beta-lactam/aminoglycoside combination courses from 32 articles were evaluated. The duration of therapy of aminoglycosides in combinations regimens ranged from 1 to 14 days, varying with the type of infection treated. In half (51.1%; (23/45) of the combinations, aminoglycosides were administered for a duration ranging from 6 to 9 days. In 26.7% (12/45) of the combinations, the duration of aminoglycoside therapy was ≤ 5 days. In the remaining 22.2% (10/45) of these combinations, the aminoglycosides were administered for a duration of ≥ 10 days. Aminoglycosides were administered for a longer duration of 7-14 days in 12 (75%) of the 16 combination courses that induced toxicity. CONCLUSIONS: Long duration of aminoglycoside use is associated with increased risk of toxicity. However, there is a lack of evidence on defining an optimal duration of aminoglycoside therapy in beta-lactam/aminoglycoside combination regimens that ensures clinical efficacy-outcomes whilst minimizing toxicity-outcomes.

A promising eco-friendly and cost-effective photocatalytic rolled graphene oxide/poly(m-methylaniline) core-shell nanocomposite for antimicrobial action.

A new and innovative rolled graphene oxide (roll-GO)/poly-m-methylaniline (PmMA) core-shell nanocomposite has been successfully synthesized using an in situ polymerization technique. This eco-friendly and cost-effective material shows great promise due to its antimicrobial properties. The characterization of the nanocomposite involved X-ray diffraction and Fourier transform infrared spectroscopy to analyze its structure and functional groups, whereas scanning electron microscopy and transmission electron microscopy (TEM) were utilized to examine its morphology. TEM analysis revealed the formation of roll-GO, forming multi-walled tubes with inner and outer diameters of 50 and 70 nm, respectively. Optical analysis demonstrated an enhanced bandgap in the nanocomposite, with bandgap values of 2.38 eV for PmMA, 2.67 eV for roll-GO, and 1.65 eV for roll-GO/PmMA. The antibacterial efficacy of the nanocomposite was tested against Gram-positive bacteria, including Bacillus subtilis and Staphylococcus aureus, as well as Gram-negative bacteria such as Escherichia coli and Salmonella sp. The well diffusion method was used to determine the inhibition zones, revealing that the nanocomposite demonstrated broad-spectrum antibacterial activity against all the pathogens tested. The largest inhibition zones were observed for B. subtilis, followed by S. aureus, E. coli, and Salmonella sp. Notably, the inhibition zones increased when the samples were exposed to light compared to dark conditions, with increases of 33 and 18 mm noted for B. subtilis. This enhanced activity under light exposure is attributed to the photocatalytic properties of the nanocomposite. The antibacterial mechanism is based on both adsorption and degradation processes. Moreover, antibacterial activity was found to increase with increasing concentrations of nanoparticles, ranging from 100 to 500 ppm. This suggests that the nanocomposite has potential as an alternative to antibiotics, especially considering the growing issue of bacterial resistance. The promising results obtained from the inhibition zones make these nanocomposites suitable for various applications. Currently, the research team is working on the development of a prototype utilizing these antimicrobial particles within commercial bottles for sterilization purposes in factories and companies.

Evaluation of the activity of antimicrobial peptides against bacterial vaginosis.

New drugs for the treatment of bacterial vaginosis (BV) are yet to be developed due to concerns that they may contribute to the increase in antibiotic resistance in BV. Antimicrobial peptides (AMPs) are one of the most promising options for next-generation antibiotics. In this study, we investigated the bacteriostatic activity of the AMPs Pexiganan, plectasin, melittin, and cathelicidin-DM against Gram-negative and Gram-positive bacteria both in vitro and in a mouse model of BV infection. The results showed that Pexiganan, melittin, and cathelicidin-DM had significant antibacterial activity against both Gram-negative and Gram-positive bacteria. AMPs have great potential for clinical application in the treatment of vaginitis, and this study provides an experimental basis for their use in the active immunoprophylaxis of BV.

Active follow-up of patients identified with multidrug-resistant gram-negative bacteria to discontinue contact precautions and isolation measures.

It is essential to refrain from unnecessary isolation measures indicated for patients identified with multidrug-resistant gram-negative bacteria (MDR-GNB) and therefore, this study aimed to evaluate whether a pro-active follow-up strategy to discontinue isolation measures of patients identified with MDR-GNB (without carbapenemase production) resulted in reduced isolation days during hospitalization, compared to passive follow-up. A comparison was made between active and passive follow-up strategies over a two-year period after first MDR-GNB identification. Patients could be declared negative after 2 consecutive negative screening cultures. Active follow-up patients received a questionnaire for screening cultures within six months of MDR-GNB identification. Of the 2208 patients included, 1424 patients (64.5%) underwent passive follow-up and 784 patients (35.5%) underwent active follow-up. A significantly higher proportion of active follow-up patients who had sufficient (at least two) screening cultures, were declared MDR-GNB negative compared to those with passive follow-up; 66.9% vs. 20.6% (P<0.001) for adult patients and 76.0% vs. 17.1% (P<0.001) for paediatric patients. A comparison between active follow-up patients with sufficient versus those with active follow-up but insufficient cultures revealed a reduction of isolation days for paediatric patients (median 10.6 vs. 1.6 days; P = 0.031). While this difference was not statistically significant for adults (median 5.3 vs 4.2 isolation days), there was a valuable decrease in the number of isolation days for both adult and paediatric patients under active follow-up with sufficient (≥2) cultures, indicating clinical relevance. Therefore, we recommend an active follow-up strategy of patients identified with an MDR-GNB, to prevent further unneeded infection prevention measures.

Development and validation of a prognostic nomogram to predict 30-day all-cause mortality in patients with CRO infection treated with colistin sulfate.

Background: Carbapenem-resistant Gram-negative organism (CRO) infection is a critical clinical disease with high mortality rates. The 30-day mortality rate following antibiotic treatment serves as a benchmark for assessing the quality of care. Colistin sulfate is currently considered the last resort therapy against infections caused by CRO. Nevertheless, there is a scarcity of reliable tools for personalized prognosis of CRO infections. This study aimed to develop and validate a nomogram to predict the 30-day all-cause mortality in patients with CRO infection who underwent colistin sulfate treatment. Methods: A prediction model was developed and preliminarily validated using CRO-infected patients treated with colistin sulfate at Tongji Hospital in Wuhan, China, who were hospitalized between May 2018 and May 2023, forming the study cohort. Patients admitted to Xianning Central Hospital in Xianning, China, between May 2018 and May 2023 were considered for external validation. Multivariate logistic regression was performed to identify independent predictors and establish a nomogram to predict the occurrence of 30-day all-cause mortality. The receiver operating characteristic (ROC) curve, the area under the ROC curve (AUC), and the calibration curve were used to evaluate model performance. The decision curve analysis (DCA) was used to assess the model clinical utility. Results: A total of 170 patients in the study cohort and 65 patients in the external validation cohort were included. Factors such as age, duration of combination therapy, nasogastric tube placement, history of previous surgery, presence of polymicrobial infections, and occurrence of septic shock were independently associated with 30-day all-cause mortality and were used to construct the nomogram. The AUC of the nomogram constructed from the above six factors was 0.888 in the training set. The Hosmer-Lemeshow test showed that the model was a good fit (p = 0.944). The calibration curve of the nomogram was close to the ideal diagonal line. Furthermore, the decision curve analysis demonstrated significantly better net benefit in the model. The external validation proved the reliability of the prediction nomogram. Conclusion: A nomogram was developed and validated to predict the occurrence of 30-day all-cause mortality in patients with CRO infection treated with colistin sulfate. This nomogram offers healthcare providers a precise and efficient means for early prediction, treatment management, and patient notification in cases of CRO infection treated with colistin sulfate.

Development of novel antimicrobials with engineered endolysin LysECD7-SMAP to combat Gram-negative bacterial infections.

BACKGROUND: Among the non-traditional antibacterial agents in development, only a few targets critical Gram-negative bacteria such as carbapenem-resistant Pseudomonas aeruginosa, Acinetobacter baumannii or cephalosporin-resistant Enterobacteriaceae. Endolysins and their genetically modified versions meet the World Health Organization criteria for innovation, have a novel mode of antibacterial action, no known bacterial cross-resistance, and are being intensively studied for application against Gram-negative pathogens. METHODS: The study presents a multidisciplinary approach, including genetic engineering of LysECD7-SMAP and production of recombinant endolysin, its analysis by crystal structure solution following molecular dynamics simulations and evaluation of antibacterial properties. Two types of antimicrobial dosage forms were formulated, resulting in lyophilized powder for injection and hydroxyethylcellulose gel for topical administration. Their efficacy was estimated in the treatment of sepsis, and pneumonia models in BALB/c mice, diabetes-associated wound infection in the leptin receptor-deficient db/db mice and infected burn wounds in rats. RESULTS: In this work, we investigate the application strategies of the engineered endolysin LysECD7-SMAP and its dosage forms evaluated in preclinical studies. The catalytic domain of the enzyme shares the conserved structure of endopeptidases containing a putative antimicrobial peptide at the C-terminus of polypeptide chain. The activity of endolysins has been demonstrated against a range of pathogens, such as Klebsiella pneumoniae, A. baumannii, P. aeruginosa, Staphylococcus haemolyticus, Achromobacter spp, Burkholderia cepacia complex and Haemophylus influenzae, including those with multidrug resistance. The efficacy of candidate dosage forms has been confirmed in in vivo studies. Some aspects of the interaction of LysECD7-SMAP with cell wall molecular targets are also discussed. CONCLUSIONS: Our studies demonstrate the potential of LysECD7-SMAP therapeutics for the systemic or topical treatment of infectious diseases caused by susceptible Gram-negative bacterial species and are critical to proceed LysECD7-SMAP-based antimicrobials trials to advanced stages.

Erosive toe-web intertrigo: Clinical features and management.

BACKGROUND: Toe-web (TW) intertrigo is a common disease of fungal or bacterial origin. Gram-negative bacterial (GNB) TW intertrigo consists of weeping, erosive, painful lesions that may be recurrent, leading to functional disability. Eczema is often associated with this condition. The management of intertrigo is poorly codified. OBJECTIVE: To evaluate the efficacy and safety of a standardized treatment plan using topical steroids in relation to the course and the frequency of recurrence of GNB-TW intertrigo. METHODS: We conducted a prospective open interventional multicentre study from June 2020 to June 2021. Standardised treatment using TCS together with follow-up via phone calls were performed over a 6-month period. In addition, a retrospective historical monocentric study was performed for patients with suspected TW-GNB intertrigo treated without standardized management. The primary endpoint was disease duration. We performed a Wilcoxon test to compare the median duration of GNB-TW intertrigo in both series. RESULTS: We included 13 patients in the prospective cohort and 14 in the retrospective cohort. In both cohorts, most patients were male with a median age of 59 years. The most frequent signs were fissures and exudates. Eczema was often associated (51.8%). Identified risk factors were psoriasis, local humidity, fungal intertrigo, vascular disease (arterial or venous insufficiency), and a history of multiple local treatments prior to diagnosis. Pseudomonas aeruginosa was the predominant pathogen (48.1%). Median durations of TW-GNB intertrigo were 56 days and 61 days. There was no significant difference in the median duration of the disease between the prospective and the retrospective cohorts (respectively61 days and 56 days; p > 0.58). Relapses were more frequent in the retrospective cohort (respectively 7.7% and 21.4%). CONCLUSION: GNB-TW intertrigo is a difficult-to-treat disease often associated with eczema. While topical corticosteroids (TCS) seem to be an effective and well-tolerated treatment they do not appear to reduce disease duration compared to other treatments.