Multidrug-resistant Pseudomonas Aeruginosa Research Articles

Molecular characteristics and antibiotic resistance mechanisms of multidrug-resistant Pseudomonas aeruginosa in Nanning, China.

This study analyzed antibiotic resistance mechanisms and molecular epidemiology of multidrug-resistant Pseudomonas aeruginosa (MDR-PA), aiming at providing clues for prevention and control of MDR-PA infections. The carbapenemase resistance genes (VIM, IMP, NDM, KPC, GES, OXA-40) of MDR-PA strains were detected by polymerase chain reaction (PCR) and sequencing. The efflux pump system (MexA, MexC, MexE, MexX), AmpC and OprD2 were detected by real-time fluorescent quantitative PCR (qPCR) in MDR-PA group and sensitive-Pseudomonas aeruginosa (S-PA) group. The homology analysis of MDR-PA strains was performed by multilocus sequence typing (MLST). A total of 81 MDR-PA strains were collected from the First Affiliated Hospital of Guangxi Medical University from October 2022 to October 2023. Among the carbapenemase detected, the detection rate of NDM-1 was the highest, with a rate of 34.57% (28/81). MexA had a higher expression in MDR-PA group than that in S-PA group (P<0.0001). 81 MDR-PA strains belonged to 40 different ST types, mainly including ST1971, ST244, ST357 and ST308, and the predominant ST type was ST1971 (34.57%, 28/81). The mechanisms of antibiotic resistance of MDR-PA strains mainly were the production of MBLS and higher expression of MexA in our study, and ST1971 was the predominant ST type of MDR-PA strains in our hospital, our findings may assist in prevention and control of MDR-PA infections.

Enhanced Antibacterial, Anti-Inflammatory, and Antibiofilm Activities of Tryptophan-Substituted Peptides Derived from Cecropin A-Melittin Hybrid Peptide BP100

The emergence of multidrug-resistant pathogens necessitates the development of novel antimicrobial agents. BP100, a short α-helical antimicrobial peptide (AMP) derived from cecropin A and melittin, has shown promise as a potential therapeutic. To enhance its efficacy, we designed and synthesized 16 tryptophan-substituted BP100 analogs based on helical wheel projections. Among these, BP5, BP6, BP8, BP11, and BP13 exhibited 1.5- to 5.5-fold higher antibacterial activity and improved cell selectivity compared to BP100. These analogs demonstrated superior efficacy in suppressing pro-inflammatory cytokine release in LPS-stimulated RAW 264.7 cells and eradicating preformed biofilms of multidrug-resistant Pseudomonas aeruginosa (MDRPA). Additionally, these analogs showed greater resistance to physiological salts and serum compared to BP100. Mechanistic studies revealed that BP100 and its analogs exert their antibacterial effects through membrane disruption, depolarization, and permeabilization. Notably, these analogs showed synergistic antimicrobial activity with ciprofloxacin against MDRPA. Our findings suggest that these tryptophan-substituted BP100 analogs represent promising candidates for combating multidrug-resistant bacterial infections, offering a multifaceted approach through their antibacterial, anti-inflammatory, and antibiofilm activities.

Multi-drug resistant Pseudomonas aeruginosa isolation is an independent risk factor for recurrent hemoptysis after bronchial artery embolization in patients with idiopathic bronchiectasis: a retrospective cohort study

BackgroundCurrently, there is a lack of research on multi-drug resistant Pseudomonas aeruginosa (MDR-PA) isolation in bronchiectasis-related hemoptysis. The aim of this study to analyze the risk factors for recurrent hemoptysis following bronchial artery embolization (BAE) and compare the recurrent hemoptysis-free rates between MDR-PA, non-MDR-PA, and non-PA isolation.MethodsA retrospective study was performed of patients diagnosed with idiopathic bronchiectasis-related recurrent hemoptysis who underwent BAE at an university-affiliated hospital. Patients were categorized based on PA susceptibility tests into non-PA, non-MDR-PA, and MDR-PA groups. Univariate and multivariate Cox regression were conducted to identify independent risk factors for recurrent hemoptysis. The Kaplan-Meier curves was conducted to compare recurrent hemoptysis-free rates after BAE for non-PA, non-MDR-PA, and MDR-PA.ResultsA total of 432 patients were included. 181 (41.90%) patients experienced recurrent hemoptysis during a median follow-up period of 25 months. MDR-PA isolation (adjusted hazard ratio (aHR) 2.120; 95% confidence interval (CI) [1.249, 3.597], p = 0.005) was identified as an independent risk factor for recurrent hemoptysis. Antibiotic treatment (aHR 0.666; 95% CI [0.476, 0.932], p = 0.018) reduced the risk of recurrent hemoptysis. The cumulative recurrent hemoptysis-free rates for non-PA, non-MDR-PA, and MDR-PA were as follows: at 3 months, 88.96%, 88.24%, and 75.86%, respectively; at 1 year, 73.13%, 69.10%, and 51.72%; and at 3 years, 61.91%, 51.69%, and 41.10% (p = 0.034).ConclusionMDR-PA isolation was an independent risk factor of recurrent hemoptysis post-BAE. Reducing the occurrence of MDR-PA may effectively decrease the recurrence rates of hemoptysis.

The Guardian of Vision: Intelligent Bacteriophage-Based Eyedrops for Clinical Multidrug-Resistant Ocular Surface Infections.

Clinical multidrug-resistant Pseudomonas aeruginosa (MDR-PA) is the leading cause of refractory bacterial keratitis (BK). However, the reported BK treatment methods lack biosecurity and bioavailability, which usually causes irreversible visual impairment and even blindness. Herein, for BK caused by clinically isolated MDR-PA infection, armed phages are modularized with the type I photosensitizer (PS) ACR-DMT, and an intelligent phage eyedrop is developed for combined phagotherapy and photodynamic therapy (PDT). These eyedrops maximize the advantages of bacteriophages and ACR-DMT, enabling more robust and specific targeting killing of MDR-PA under low oxygen-dependence, penetrating and disrupting biofilms, and efficiently preventing biofilm reformation. Altering the biofilm and immune microenvironments alleviates inflammation noninvasively, promotes corneal healing without scar formation, protects ocular tissues, restores visual function, and prevents long-term discomfort and pain. This strategy exhibits strong scalability, enables at-home treatment of ocular surface infections with great patient compliance and a favorable prognosis, and has significant potential for clinical application.

Ceftazidime-avibactam versus other antimicrobial agents for treatment of Multidrug-resistant Pseudomonas aeruginosa: a systematic review and meta-analysis.

Multidrug-resistant Pseudomonas aeruginosa (MDR-PA) is a life-threatening infection with limited treatment options. This is the first meta-analysis of recently published data to compare the clinical outcomes of ceftazidime-avibactam (CAZ-AVI) with other antimicrobial agents in treating MDR-PA infections. Systematic review and meta-analysis. PubMed, Embase and the Cochrane Library have been systematically reviewed, for publications in the English language, from database inception to July 2023. Studies comparing CAZ-AVI outcomes with other antimicrobial agents were included. In-hospital mortality & 30-day mortality were assessed as the main outcomes. Literature screening, data extraction, and the quality evaluation of studies were conducted by two researchers independently, with disagreements resolved by another researcher. The Newcastle-Ottawa Scale was used to assess the bias risk for the included studies. Review Manager V.5.4 was employed for the meta-analysis. The meta-analysis included four retrospective studies, enrolling 1934 patients. The CAZ-AVI group demonstrated significantly lower in-hospital mortality (risk ratio (RR) = 0.60, 95% CI:0.37-0.97, I2 = 74%, p = 0.04) in three studies with 1444 patients and lower 30-day mortality, in 438 patients from three studies (RR = 0.54, 95% CI:0.28-1.05, I2 = 67%, p = 0.07). No significant difference in clinical success, microbiological success, length of hospital, and ICU stay was observed. This meta-analysis demonstrated that CAZ-AVI treatment significantly lowered in-hospital mortality compared with other antimicrobial agents in MDR-PA infections. However, the analysis only included a few observational studies and high-quality, randomized controlled trials are needed to investigate further the scope of CAZ-AVI in MDR-PA infections.

The Changes in Broad-spectrum Antimicrobial Consumption during the COVID-19 Pandemic in a Japanese Acute Tertiary-care Hospital: An Interrupted Time-series Analysis.

Objective The novel coronavirus disease 2019 (COVID-19) pandemic has spread worldwide, and hospitals in Japan have been forced to respond to the situation. This study evaluated the broad-spectrum antimicrobial use before and during the COVID-19 pandemic in an acute tertiary-care hospital. Methods This single-center, retrospective study was conducted between January 2019 and June 2021. Patients We reviewed patients treated with three broad-spectrum antipseudomonal agents: carbapenems, tazobactam/piperacillin, and cefepime. Monthly aggregated hospital antimicrobial consumption was measured as days of therapy (DOTs) per 1,000 patient-days, and the monthly incidences of Clostridioides difficile infection (CDI), multidrug-resistant Pseudomonas aeruginosa (MRPA), and carbapenemase-producing Enterobacteriaceae (CPE) were recorded. Results The median monthly carbapenem-DOTs during the pre-pandemic and pandemic era were 8.4 and 8.2 per 1,000 patient-days, respectively. A time-series analysis showed non-significant changes in the level between periods (coefficients: 2.08; 95% confidence interval [CI]: -2.9 to 7.0; p=0.44). No change in the trend of monthly carbapenem-DOTs was observed after intervention. No post-intervention changes in the incidence of MRPA or CPE were observed; however, the trend in the incidence of CDI per 1,000 patient-days significantly differed between the two periods (coefficient: -0.04; 95% CI: -0.07, 0.00; p=0.01), and a downward trend was observed in the monthly CDI incidence during the COVID-19 period. Conclusion The consumption of broad intravenous antimicrobial agents has not changed significantly during the pandemic. We need to maintain the quality of medical care, including antimicrobial stewardship, even in specialized resource-limited facilities during a pandemic.

Enhancing Selective Antimicrobial and Antibiofilm Activities of Melittin through 6-Aminohexanoic Acid Substitution.

Leucine residues are commonly found in the hydrophobic face of antimicrobial peptides (AMPs) and are crucial for membrane permeabilization, leading to the cell death of invading pathogens. Melittin, which contains four leucine residues, demonstrates broad-spectrum antimicrobial properties but also significant cytotoxicity against mammalian cells. To enhance the cell selectivity of melittin, this study synthesized five analogs by replacing leucine with its structural isomer, 6-aminohexanoic acid. Among these analogs, Mel-LX3 exhibited potent antibacterial activity against both Gram-positive and Gram-negative bacteria. Importantly, Mel-LX3 displayed significantly reduced hemolytic and cytotoxic effects compared to melittin. Mechanistic studies, including membrane depolarization, SYTOX green uptake, FACScan analysis, and inner/outer membrane permeation assays, demonstrated that Mel-LX3 effectively permeabilized bacterial membranes similar to melittin. Notably, Mel-LX3 showed robust antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant Pseudomonas aeruginosa (MDRPA). Furthermore, Mel-LX3 effectively inhibited biofilm formation and eradicated existing biofilms of MDRPA. With its improved selective antimicrobial and antibiofilm activities, Mel-LX3 emerges as a promising candidate for the development of novel antimicrobial agents. We propose that the substitution of leucine with 6-aminohexanoic acid in AMPs represents a significant strategy for combating resistant bacteria.

Hyaluronidase-Responsive Bactericidal Cryogel for Promoting Healing of Infected Wounds: Inflammatory Attenuation, ROS Scavenging, and Immune Regulation.

Wounds infected with multidrug-resistant (MDR) bacteria are increasingly threatening public health and challenging clinical treatments because of intensive bacterial colonization, excessive inflammatory responses, and superabundant oxidative stress. To overcome this malignant burden and promote wound healing, a multifunctional cryogel (HA/TA2/KR2) composed of hyaluronic acid (HA), tannic acid (TA), and KR-12 peptides is designed. The cryogel exhibited excellent shape-memory properties, strong absorption performance, and hemostatic capacity. In vitro experiments demonstrated that KR-12 in the cryogel can be responsively released by stimulation with hyaluronidase produced by bacteria, reaching robust antibacterial activity against Escherichia coli (E. coli), MDR Pseudomonas aeruginosa (MDR-PA), and methicillin-resistant Staphylococcus aureus (MRSA)by disrupting bacterial cell membranes. Furthermore, the synergetic effect of KR-12 and TA can efficiently scavenge ROS and decrease expression of pro-inflammatory cytokines (tumor necrosis factor (TNF)-α & interleukin (IL)-6), as well as modulate the macrophage phenotype toward the M2 type. In vivo animal tests indicated that the cryogel can effectively destroy bacteria in the wound and promote healing process via accelerating angiogenesis and re-epithelialization. Proteomic analysis revealed the underlying mechanism by which the cryogel mainly reshaped the infected wound microenvironment by inhibiting the Nuclear factor kappa B (NF-κB) signaling pathway and activating the Janus kinase-Signal transducer and activator of transcription (JAK-STAT6) signaling pathway. Therefore, the HA/TA2/KR2 cryogel is a promising dressing candidate for MDR bacteria-infected wound healing.

Multi-comparted microgels delivering human derived probiotics and deferoxamine for multidrug-resistant infection and healing

Infection and vascular dysfunction are two major reasons for delayed wound healing, especially in the scenario of multidrug-resistant bacterial has been a challenge for antibiotics usage. Probiotics are effective in fighting pathogens, while avoiding the destruction of skin microbiome. However, the viability of probiotics is a major obstacle in clinical application. As a non-protein proangiogenic drug, deferoxamine (DFO) has significant advantages over traditional growth factors in terms of cost, storage and transportation conditions, and stability. However, there is still a problem of short half-life that requires reliable drug delivery carriers to maximize its effect. Here, we developed multiple-chambered microgels using electrospray and microfluidics. Lactobacillus fermentum (LF) and DFO, respectively, for the management of multidrug-resistant Pseudomonas aeruginosa (MPA) and promotion of wound healing. We first tested five probiotics isolated from healthy people and found LF inhibiting the growth of MPA by lowering local pH and antimicrobial substances. The multi-chambered microgels effectively inhibited MPA by delivering probiotics, they can also protect probiotics from antibiotics. DFO promoted the angiogenesis of human umbilical venous endothelial cells. The microgel system had good biocompatibility and hemocompatibility. In a MPA infected wound, the microgel system effectively alleviated wound infection by 87.44%, improved angiogenesis by 29.32% and accelerated wound healing. This work suggests that multi-compartmented microgels loaded with probiotics and deferoxamine have great potential in wounds with multidrug-resistant bacteria.

Amine Basicity of Quinoline ATP Synthase Inhibitors Drives Antibacterial Activity against Pseudomonas aeruginosa.

Pseudomonas aeruginosa (PA), a Gram-negative pathogen, is a common cause of nosocomial infections, especially in immunocompromised and cystic fibrosis patients. PA is intrinsically resistant to many currently prescribed antibiotics due to its tightly packed, anionic lipopolysaccharide outer membrane, efflux pumps, and ability to form biofilms. PA can acquire additional resistance through mutation and horizontal gene transfer. PA ATP synthase is an attractive target for antibiotic development because it is essential for cell survival even under fermentation conditions. Previously, we developed two lead quinoline compounds that were capable of selectively inhibiting PA ATP synthase and acting as antibacterial agents against multidrug-resistant PA. Herein we conduct a structure-activity relationship analysis of the lead compounds through the synthesis and evaluation of 18 quinoline derivatives. These compounds function as new antibacterial agents while providing insight into the balance of physical properties needed to promote cellular entry while maintaining PA ATP synthase inhibition.

Is Short-Course Antibiotic Therapy Suitable for Pseudomonas Aeruginosa Bloodstream Infections in Onco-Hematology Patients with Febrile Neutropenia? Results of a Multi-Institutional Analysis

Background. Several studies have suggested that short-course antibiotic therapy does not increase infection recurrence or mortality in immunocompetent patients. While similar studies in patients with hematological malignancies were rare. Methods. This cohort included onco-hematology patients with Pseudomonas aeruginosa (PA) bloodstream infections (BSI). These patients had undergone chemotherapy or hematopoietic stem cell transplantation (HSCT) and experienced febrile neutropenia. Inverse probability of treatment weighting was used to balance the confounding factors. Results. 434 patients met eligibility criteria (short-course, 7-11 days, n=229; prolonged therapy, 12-21 days, n=205). In the weighted cohort, after multivariate analysis, the recurrent PA infection at any site or mortality within 30 days of completing therapy occurred in 8 (3.9%) patients in the short-course group and in 10 (4.9%) in the prolonged-course group ( p = 0.926), the recurrent infection within 90 days occurred in 20 (9.8%) patients in the short-course group and in 13 (6.3%) patients in the prolonged-course group ( p =0.276), and the recurrent fever within 7 days occurred in 17 (8.3%) patients in the short-course group and in 15 (7.4%) in the prolonged-course group ( p = 0.980). While multidrug-resistant PA, relapsed/refractory hematological malignancies and perianal mucositis were the key determinants of infection recurrence/mortality other than the short course of antibiotic treatment (p&amp;lt;0.05 for all). On average, patients who received short-course antibiotic therapy spent 3.3 fewer days in the hospital ( p&amp;lt;0.001). Conclusions. We found that onco-hematology patients with PA BSI who received approximately 8 days of antibiotics had similar clinical outcomes to those who received a prolonged-course therapy, with the potential added benefit of earlier hospital discharge.

In vitro, molecular docking and in silico/ADMET study of cuminaldehyde against Candida, MDR bacteria and human colorectal and cervical carcinoma

Many people have recently been diagnosed with cancer and other multi-resistant infections. These illnesses are now considered among the leading causes of mortality worldwide. In addition, infectious organisms such as microbes and viruses are responsible for around 2 million new cancer cases. Cuminaldehyde (CUM), the main bioactive component of Cuminum cyminum, also called 4-isopropylbenzaldehyde, is the most prevalent in C. cyminum seeds. Extensive research has been conducted on natural compounds in general; however, the investigation of CUM, a unique component of cumin oil, is still in its preliminary phases. Therefore, this study aimed to screen CUM for possible anticancer (colon cancer HCT-116 and cervical cancer HeLa cells), antibacterial, and antifungal activities. The number of DAPI-stained cells was lower in the CUM treatment group compared to the control group. The results showed that the minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) for Gram-negative bacteria, i.e., Escherichia coli ATCC 25922, multidrug-resistant Pseudomonas aeruginosa (MDR-PA), and multidrug-resistant Acinetobacter baumannii (MDR-A. baumannii), were 6.25/12.5, 12.5/25, and 6.25/12.5 mM, respectively, while the MICs for Gram-positive bacteria Staphylococcus aureus ATCC 25923, and methicillin-resistant S. aureus (MRSA) were 25/50 and 6.25/12.5 mM, respectively. However, MIC and minimum fungicidal concentration (MFC) values against Candida albicans ATCC 14053 were 6.25 and 12.5 mM, respectively. In addition, the anticancer and antibacterial efficacy of CUM has also been analyzed by an in silico molecular docking study, which demonstrated noteworthy binding energy with the sterol 14-alpha demethylase (-5.53 kcal/mol), followed by cyclin-dependent kinase 2 (-5.35 kcal/mol), poly-beta-1,6-N-acetyl-d-glucosamine synthase (-4.90 kcal/mol), GDP-mannose dehydrogenase (-4.35 kcal/mol), and intact bacterial peptidoglycan (-2.65 kcal/mol). Our predicted results need to be further validated through in vitro and in vivo studies before they can be applied to the development of therapeutic compound against cancer and infectious diseases, two of humanity's gravest health issues.

Экспериментальное лечение эндофтальмита, вызванного синегнойной инфекцией с множественной лекарственной устойчивостью, с помощью конъюгатов на основе наночастиц

Relevance. Pseudomonas aeruginosa (PA) is an extremely dangerous microorganism whose elimination from the host organism is very difficult due to the presence of multidrug resistance (MDR) factors in PA. The outcome of endophthalmitis (EP) mediated by PA in 50% of cases will be evisceration of the eyeball, and more than 95% of patients receive visual acuity – hand movements near the face and below. In this regard, studies of quantum dots (QDs), which have shown high anti-infective activity in laboratory conditions, are of particular relevance. Purpose. Evaluation of the effectiveness of the treatment of EP caused by PA with MDR using QDs-based conjugates in the experiment. Material and methods. The object of the study was laboratory rabbits of the Chinchilla breed (n=27), male, aged from 3 to 3.5 months. As an EP inducer, all laboratory animals underwent intravitreal injection (IVI) of a multidrug-resistant PA strain in a volume of 0.05 ml in the right eye. QDs of the Ag (10%):InP/ZnS MPA type were taken as the basis for the creation of conjugates with antibiotics (AB). After the manifestation of EP, the animals underwent intravitreal injections (IVI) of dosage forms in accordance with the distribution into the following subgroups, 3 rabbits in each. Subgroups No. 1–3 – IVI 2.25 mg/0.1 ml Ceftazidime. Subgroups No. 4–6 – IVI 0.1 ml of QDs solution at concentrations of 10%, 0.1%, 0.01%, respectively. Subgroups No. 7–9 – IVI solution of QDs 0.05 ml (at concentrations of 10%, 0.1%, 0.01%, respectively) in combination with 2.25 mg/0.05 ml of Ceftazidime (conjugates). Efficacy was evaluated based on clinical parameters: the dynamics of hypopyon resorption, the presence of inflammatory cells in the anterior chamber, the dynamics of regression of pathological suspension in the vitreal cavity, the dynamics of pathological neovascularization of the iris, the dynamics of the cornea. Results. Rabbits from subgroups No. 1–3 (1st group) were characterized by the least dynamics in relation to the regression of symptoms during the 7-day observation period. Rabbits from subgroups No. 4–6 (2nd group) were characterized by moderate positive dynamics in relation to the regression of symptoms. Rabbits from subgroups No. 7–9 (3rd group) were characterized by the best positive dynamics in relation to the regression of symptoms. Conclusion. It was possible to prove the effectiveness of the treatment of experimental antibiotic-resistant EP caused by a strain of PA with MDR by means of QDs Ag(10%):InP/ZnS MPA at concentrations of 10%, 0.1% and 0.01%, especially in combination with 2.25 mg/0.05 ml of Ceftazidime in as a conjugate. Based on the results obtained, it can be assumed that active research and the use of QDs as conjugates with modern ABs can solve the overall problem of combating MDR strains. Key words: Pseudomonas Aeruginosa, quantum dots, endophthalmitis, multidrug resistance, antibiotic resistance, conjugates

Determination of Multidrug Resistance and Extended Drug Resistance Pattern of Pseudomonas aeruginosa in Clinical Isolates of Tertiary Care Hospital Lahore

Background: &#x0D; Pseudomonas aeruginosa (PA) is a major public health community-acquired threat around the globe due to the growing rate of antimicrobial resistance. It is one of the most common trending causes of nosocomial infections. &#x0D; Objective: &#x0D; The current study aimed to check the rate of multidrug-resistant (MDR) and extended drug-resistant (XDR) PA and to analyze the invitro activity of different antimicrobial agents against clinically isolated bacterial samples. Molecular Detection and amplification of L lipoprotein (OprL gene) were also done to determine the frequency and species of different strains of Pseudomonas aeruginosa (PA2192, C3719, PA01, PA14 and PACS2).&#x0D; Method:&#x0D; This cross-sectional study was conducted at at the Department of Pathology, King Edward Medical University/ Mayo Hospital Lahore. Total 140 patients were included in the study. Biochemical characterization, molecular identification, antimicrobial susceptibility profiling and DNA sequencing of the desired gene were done to confirm different strains' identification. &#x0D; Results:&#x0D; MDR and XDR Pseudomonas aeruginosa infection are more common among males 81(57.5%) and high among the 31-45 age group, i.e., 55 (39.3%). After antibiotic susceptibility testing, 60% of strains were found to be MDR PA, while 40% were categorized as XDR PA. Doripenem showed the highest sensitivity, 93 (66.4%) among all carbapenems. Polymyxin B showed the highest activity against Pseudomonas aeruginosa multi and extensively drug-resistant strains, i.e., 108 (77.1%). &#x0D; Conclusion:&#x0D; The present study suggests that doripenem can be the only active agent for combating infections, and the Carbapenem drug appears effective against highly resistant strains of Pseudomonas aeruginosa.&#x0D;

Multifunctional Properties of BMAP-18 and Its Aliphatic Analog against Drug-Resistant Bacteria.

BMAP-18, derived from the N-terminal region of bovine myeloid antimicrobial peptide BMAP-27, demonstrates potent antimicrobial activity without cytotoxicity. This study aimed to compare the antibacterial, antibiofilm, and anti-inflammatory properties of BMAP-18, rich in aromatic phenylalanine residues, with its aliphatic analog, BMAP-18-FL. Both aromatic BMAP-18 and aliphatic BMAP-18-FL exhibited equally potent antimicrobial activities against Gram-positive and Gram-negative bacteria, particularly methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant Pseudomonas aeruginosa (MDRPA). Mechanistic investigations employing SYTOX green uptake, DNA binding, and FACScan analysis revealed that both peptides acted by inducing membrane permeabilization and subsequent intracellular targeting. Moreover, both BMAP-18 and BMAP-18-FL effectively prevented biofilm formation and eradicated existing biofilms of MRSA and MDRPA. Notably, BMAP-18-FL displayed a superior anti-inflammatory activity compared to BMAP-18, significantly reducing the expression levels of pro-inflammatory cytokines in lipopolysaccharide-stimulated macrophages. This study emphasizes the similarities and differences in the antimicrobial, antibiofilm, and anti-inflammatory properties between aromatic BMAP-18 and aliphatic BMAP-18-FL, providing valuable insights for the development of multifunctional antimicrobial peptides against drug-resistant bacteria.

Antibacterial Activities of Fungal Endophytes from Philippine Endemic Plant Dillenia philippinensis

Fungal endophytes represent a group of microorganisms that establish symbiotic associations with plants and hold significant ecological importance. Their ability to produce a diverse array of biologically active secondary metabolites has garnered considerable interest in the search for novel drug leads. In this study a total of 33 fungal endophytes were isolated from leaf specimens of the Philippine endemic tree Dillenia philippinensis (Rolfe). The morphological characterization of the fungal isolates revealed their taxonomic affiliation with the following eight genera: Alternaria sp., Aspergillus sp., Geotrichum sp., Guignardia sp., Nigrospora sp., Paecilomyces sp., Pestalotiopsis sp., and Phialophora sp. A representative set of 22 fungal endophyte isolates was selected from the pool of isolates and subjected to large-scale cultivation, followed by extraction of their bioactive metabolites through liquid-submerged fermentation. The resulting crude extracts were evaluated for their inhibitory potential against two Gram-positive bacteria, namely Staphylococcus aureus and Methicillin-resistant Staphylococcus aureus (MRSA); and two Gram-negative bacteria, namely Escherichia coli and Multi-drug resistant Pseudomonas aeruginosa (MRPA), using the disc diffusion assay. The results indicate that the crude extracts obtained from endophytic fungi colonizing D. philippinensis represent a promising source of bioactive metabolites that exhibit noteworthy inhibitory activity against S. aureus, E. coli, and MRSA, with an effective concentration of 10 mg/mL. This study demonstrates that the fungal endophytes associated with Dillenia philippinensis foliage represent a rich source of bioactive metabolites with significant inhibitory activity against Gram-positive and Gram-negative bacteria. These lead to exploring the potential of these fungal endophytes as a viable source of novel therapeutics.

Evaluation of deoxythymidine-based cationic amphiphiles as antimicrobial, antibiofilm, and anti-inflammatory agents

ObjectivesWe recently designed a series of cationic deoxythymidine-based amphiphiles that mimic the cationic amphipathic structure of antimicrobial peptides (AMPs). Among these amphiphiles, ADG-2e and ADL-3e displayed the highest selectivity against bacterial cells. In this study, ADG-2e and ADL-3e were evaluated for their potential as novel classes of antimicrobial, antibiofilm, and anti-inflammatory agents. MethodsMinimum inhibitory concentrations of ADG-2e and ADL-3e against bacteria were determined using the broth microdilution method. Proteolytic resistance against pepsin, trypsin, α-chymotrypsin, and proteinase K was determined by radial diffusion and HPLC analysis. Biofilm activity was investigated using the broth microdilution and confocal microscopy. The antimicrobial mechanism was investigated by membrane depolarization, cell membrane integrity analysis, scanning electron microscopy (SEM), genomic DNA influence and genomic DNA binding assay. Synergistic activity was evaluated using checkerboard method. Anti-inflammatory activity was investigated using ELISA and RT-PCR. ResultsADG-2e and ADL-3e showed good resistance to physiological salts and human serum, and a low incidence of drug resistance. Moreover, they exhibit proteolytic resistance against pepsin, trypsin, α-chymotrypsin, and proteinase K. ADG-2e and ADL-3e were found to kill bacteria by an intracellular target mechanism and bacterial cell membrane-disrupting mechanism, respectively. Furthermore, ADG-2e and ADL-3e showed effective synergistic effects when combined with several conventional antibiotics against methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant Pseudomonas aeruginosa (MDRPA). Importantly, ADG-2e and ADL-3e not only suppressed MDRPA biofilm formation but also effectively eradicated mature MDRPA biofilms. Furthermore, ADG-2e and ADL-3e drastically decreased tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) gene expression and protein secretion in lipopolysaccharide (LPS)-stimulated macrophages, implying potent anti-inflammatory activity in LPS-induced inflammation. ConclusionOur findings suggest that ADG-2e and ADL-3e could be further developed as novel antimicrobial, antibiofilm, and anti-inflammatory agents to combat bacterial infections.

Assessment of mortality-related risk factors and effective antimicrobial regimens for treatment of bloodstream infections caused by carbapenem-resistant Pseudomonas aeruginosa in patients with hematological diseases.

Infections caused by carbapenem-resistant Pseudomonas aeruginosa (CRPA) are related to higher mortality. The objective of this study was to explore clinical outcomes of CRPA bacteremia, identify risk factors and also, compare the efficacy of traditional and novel antibiotic regimens. This retrospective study was conducted at a blood diseases hospital in China. The study included hematological patients who were diagnosed with CRPA bacteremia between January 2014 and August 2022. The primary endpoint was all-cause mortality at day 30. Secondary endpoints included 7-day and 30-day clinical cure. Multivariable Cox regression analysis was employed to identify mortality-related risk factors. 100 patients infected with CRPA bacteremia were included and 29 patients accepted allogenic-hematopoietic stem cell transplantation. 24 received ceftazidime-avibactam (CAZ-AVI)-based therapy and 76 received other traditional antibiotics. 30-day mortality was 21.0%. Multivariable cox regression analysis showed neutropenia >7 days after bloodstream infections (BSI) (P=0.030, HR: 4.068, 95%CI: 1.146~14.434), higher Pitt bacteremia score (P<0.001, HR:1.824, 95%CI: 1.322~2.517), higher Charlson comorbidity index (P=0.01, HR: 1.613, 95%CI: 1.124~2.315) and bacteremia due to multidrug-resistant Pseudomonas aeruginosa (MDR-PA) (P=0.024, HR:3.086, 95%CI: 1.163~8.197) were identified as independent risk factors of 30-day mortality. After controlling for confounders, an additional multivariable cox regression analysis revealed definitive regimens containing CAZ-AVI were associated with lower mortality in CRPA bacteremia (P=0.016, HR: 0.150, 95%CI: 0.032~0.702), as well as in MDR-PA bacteremia (P=0.019, HR: 0.119, 95%CI: 0.020~0.709). For patients with hematological diseases and CRPA bacteremia, 30-day mortality rate was 21.0% (21/100). Neutropenia >7 days after BSI, higher Pitt bacteremia score, higher Charlson comorbidity index and bacteremia due to MDR-PA increased 30-day mortality. CAZ-AVI-based regimens were effective alternatives for bacteremia due to CRPA or MDR-PA.

Activity of Delafloxacin and Comparator Fluoroquinolones against Multidrug-Resistant Pseudomonas aeruginosa in an In Vitro Cystic Fibrosis Sputum Model.

Delafloxacin (DLX) is a recently approved fluoroquinolone with broad activity against common cystic fibrosis (CF) pathogens, including multidrug-resistant Pseudomonas aeruginosa (MDR-Psa). Delafloxacin has been previously shown to have excellent lung and biofilm penetration and enhanced activity at lower pH environments, such as those that would be observed in the CF lung. We analyzed six Psa strains isolated from CF sputum and compared DLX to ciprofloxacin (CPX) and levofloxacin (LVX). Minimum inhibitory concentrations (MICs) were determined for DLX using standard culture media (pH 7.3) and artificial sputum media (ASM), a physiologic media recapitulating the CF lung microenvironment (pH 6.9). Delafloxacin activity was further compared to CPX and LVX in an in vitro CF sputum time-kill model at physiologically relevant drug concentrations (Cmax, Cmed, Cmin). Delafloxacin exhibited 2- to 4-fold MIC reductions in ASM, which corresponded with significant improvements in bacterial killing in the CF sputum time-kill model between DLX and LVX at Cmed (p = 0.033) and Cmin (p = 0.004). Compared to CPX, DLX demonstrated significantly greater killing at Cmin (p = 0.024). Overall, DLX demonstrated favorable in vitro activity compared to alternative fluoroquinolones against MDR-Psa. Delafloxacin may be considered as an option against MDR-Psa pulmonary infections in CF.

NIR-II Responsive Nanohybrids Incorporating Thermosensitive Hydrogel as Sprayable Dressing for Multidrug-Resistant-Bacteria Infected Wound Management.

Developing an effective dressing against bacterial infection and synchronously addressing wound complications, such as bleeding, long-term inflammation, and reinfection, are highly desirable in clinical practice. In this work, a second near-infrared (NIR-II) responsive nanohybrid consisting of imipenem encapsulated liposome with gold-shell and lipopolysaccharide (LPS)-targeting aptamer, namely ILGA, is constructed for bacteria elimination. Benefiting from the delicate structure, ILGA exhibits strong affinity and a reliable photothermal/antibiotic therapeutic effect toward multidrug-resistant Pseudomonas aeruginosa (MDR-PA). Furthermore, by incorporating ILGA with a thermosensitive hydrogel poly(lactic-co-glycolic acid)-polyethylene glycol-poly(lactic-co-glycolic acid) (PLGA-PEG-PLGA), a sprayable dressing ILGA@Gel was prepared, which enables a quick on-demand gelation (10 s) for wound hemostasis and offers excellent photothermal/antibiotic efficacy to sterilize the infected wound. Additionally, ILGA@Gel provides satisfactory wound-healing environments by reeducating wound-associated macrophages for inflammation alleviation and forming a gel layer to block exogenous bacterial reinfection. This biomimetic hydrogel reveals excellent bacteria eradication and wound recovery effectiveness, demonstrating its promising potential for managing complicated infected wounds.