Hospital-acquired infections due to gram-negative bacteria

Characterization and genetic analysis of extensively drug-resistant hospital acquired Pseudomonas aeruginosa isolates

BACKGROUND

The incidence of hospital-acquired infections in extensively drug-resistant Pseudomonas aeruginosa (XDR-PA) has been increasing worldwide and is frequently associated with an increase in mortality and morbidity rates. The aim of this study was to characterize clinical XDR-PA isolates recovered during six months at three different hospitals in Egypt.

RESULTS

Seventy hospital-acquired clinical isolates of P. aeruginosa were classified into multidrug-resistant (MDR), extensively drug-resistant (XDR) and pandrug-resistant (PDR), according to their antimicrobial resistance profile. In addition, the possession of genes associated with mobile genetic elements and genes encoding antimicrobial resistance determinants among isolates were detected using polymerase chain reaction. As a result, a significant percentage of the isolates (75.7%) were XDR, while 18.5% were MDR, however only 5.7% of the isolates were non-MDR. The phenotypic detection of carbapenemases, extended-spectrum β-lactamases (ESBLs) and metallo β-lactamase (MBL) enzymes showed that 73.6% of XDR-PA isolates were carbapenemases producers, whereas 75.5% and 88.7% of XDR-PA isolates produced ESBLs and MBL respectively. In addition, PCR screening showed that oxa gene was the most frequently detected gene of carbapenemases (91.4%), while aac(6')-lb gene was mostly detected (84.3%) among the screened aminoglycosides-resistance genes. Furthermore, the molecular detection of the colistin resistance gene showed that 12.9% of isolates harbored mcr-1 gene. Concerning mobile genetic element markers (intI, traA, tnp513, and merA), intI was the highest detected gene as it was amplified in 67 isolates (95.7%). Finally, phylogenetic and molecular typing of the isolates via ERIC-PCR analysis revealed 10 different ERIC fingerprints.

CONCLUSION

The present study revealed a high prevalence of XDR-PA in hospital settings which were resistant to a variety of antibiotics due to several mechanisms. In addition, 98% of the XDR-PA clinical isolates contained at least one gene associated with movable genetic elements, which could have aided the evolution of these XDR-PA strains. To reduce spread of drug resistance, judicious use of antimicrobial agents and strict infection control measures are therefore essential.

Genomic Characterization of Multidrug-Resistant Enterobacteriaceae Clinical Isolates from Southern Thailand Hospitals: Unraveling Antimicrobial Resistance and Virulence Mechanisms

The emergence and spread of antimicrobial resistance (AMR) among Enterobacteriaceae pose significant threats to global public health. In this study, we conducted a short-term surveillance effort in Southern Thailand hospitals to characterize the genomic diversity, AMR profiles, and virulence factors of Enterobacteriaceae strains. We identified 241 carbapenem-resistant Enterobacteriaceae, of which 12 were selected for whole-genome sequencing (WGS) and genome analysis. The strains included Proteus mirabilis, Serratia nevei, Klebsiella variicola, Klebsiella aerogenes, Klebsiella indica, Klebsiella grimontii, Phytobacter ursingii, Phytobacter palmae, Kosakonia spp., and Citrobacter freundii. The strains exhibited high levels of multidrug resistance, including resistance to carbapenem antibiotics. Whole-genome sequencing revealed a diverse array of antimicrobial resistance genes (ARGs), with strains carrying genes for ß-lactamase, efflux pumps, and resistance to other antibiotic classes. Additionally, stress response, metal tolerance, and virulence-associated genes were identified, highlighting the adaptability and pathogenic potential of these strains. A plasmid analysis identified several plasmid replicons, including IncA/C2, IncFIB(K), and Col440I, as well as several plasmids identical to those found globally, indicating the potential for the horizontal gene transfer of ARGs. Importantly, this study also identified a novel species of Kosakonia spp. PSU27, adding to the understanding of the genetic diversity and resistance mechanisms of Enterobacteriaceae in Southern Thailand. The results reported in this study highlight the critical importance of implementing effective antimicrobial management programs and developing innovative treatment approaches to urgently tackle AMR.

Diagnostic value of Procalcitonin, C-reactive protein-to-lymphocyte ratio (CLR), C-reactive protein and neutrophil-to-lymphocyte ratio (NLR) for predicting patients with Bacteraemia in the intensive care unit

BACKGROUND

To explore the diagnostic value of procalcitonin (PCT), C-reactive protein-to-lymphocyte ratio (CLR), C-reactive protein (CRP) and neutrophil-to-lymphocyte ratio (NLR) for predicting patients with bacteremia in the intensive care unit (ICU).

METHODS

This case-control study included 359 patients with suspected bacteremia were divided into a bacteremia group (n = 152) and a control group (n = 207) from September 2018 to April 2023. Patient data were collected using a laboratory information system (LIS). ROC curves for PCT, CLR, CRP, and NLR in predicting patients with bacteremia.

RESULTS

For PCT, CLR, CRP and NLR to predict patients with bacteremia in the ICU, the AUCs were 0.991(95%CI: 0.974-0.998), 0.960(95%CI: 0.935-0.978), 0.955(95%CI: 0.928-0.974), and 0.898(95%CI:0.862-0.927), respectively; the optimal thresholds were 0.248 ng/mL, 47.52 mg/109, 48.32 mg/L, and 6.51, respectively; the sensitivities were 95.4(95%CI: 90.7-98.1), 88.2(95%CI: 81.9-92.8), 87.5(95%CI: 81.2-92.3), and 86.8(95%CI:80.4-91.8), respectively; and the specificities were 95.7(95%CI: 91.9-98.0), 90.8(95%CI: 86.0-94.4), 90.3(95%CI: 85.5-94.0), and 85.0(95%CI:79.4-89.6), respectively. The sensitivities of PCT, CLR, CRP and NLR for predicting bacteremia due to E. coli infection are as high as over 90%, the specificity of PCT is 100, and the sensitivity of NLR is 100. The sensitivity of CRP for predicting bacteremia due to non-Enterobacer infection is 100.

CONCLUSIONS

Compared with those in the control group, PCT, CLR, CRP and NLR were significantly greater in the bacteremia group. The PCT, CLR, CRP, and NLR can all predict the occurrence of bacteremia. The PCT had the highest sensitivity and specificity in predicting bacteremia in ICU patients.

Antibiotic prescribing and bacterial infection in COVID-19 inpatients in Southeast Asia: a systematic review and meta-analysis

Background

The prescribing of antibiotics to treat COVID-19 patients has been observed to occur frequently, often without clear justification. This trend raises concerns that it may have exacerbated antimicrobial resistance (AMR). Despite longstanding concerns over AMR in Southeast Asian countries, data on this issue are notably lacking.

Objectives

To explore the impact of COVID-19 on antibiotic prescribing, bacterial infection prevalence and common resistant pathogens in COVID-19 inpatients.

Methods

We searched PubMed, EMBASE, Web of Science and ThaiJO (a Thai academic database) to identify studies conducted in ASEAN member countries and published between December 2019 and March 2023. Screening and data extraction were done by two independent reviewers, with results synthesized using random-effects meta-analyses and descriptive statistical analyses. This review was registered with PROSPERO (CRD42023454337).

Results

Of the 29 studies (19 750 confirmed COVID-19 cases) included for final analysis, the antibiotic prescribing rate was 62.0% (95%CI: 46.0%-76.0%) with a prescribing rate of 58.0% (21.0%-91.0%) in mild/moderate cases versus 91.0% (82.0%-98.0%) in severe/critical cases. Notably, 80.5% of antibiotics prescribed fall under the WHO AWaRe 'Watch' list, followed by 'Access' at 18.4% and 'Reserve' at 1.0%. The reported bacterial infection prevalence was 16.0% (7.0%-29.0%), with Acinetobacter baumannii being the most common resistant bacterium at 7.7%. Singapore was notable for its lower antibiotic prescribing rate of 17.0% and a lower bacterial infection rate of 10.0%.

Conclusions

High antibiotic prescribing rates, disproportionate to bacterial infections and varying practices for COVID-19 inpatients across countries highlight the urgent need for this region to collaborate to tackle and mitigate AMR.

Epidemiology of healthcare-associated Pseudomonas aeruginosa in intensive care units: are sink drains to blame?

BACKGROUND

Pseudomonas aeruginosa (PA) is a common cause of healthcare-associated infection (PA-HAI) in the intensive care unit (ICU).

AIM

To describe the epidemiology of PA-HAI in ICUs in Ontario, Canada, and to identify episodes of sink-to-patient PA transmission.

METHODS

This was a prospective cohort study of patients in six ICUs from 2018 to 2019, with retrieval of PA clinical isolates, and PA-screening of antimicrobial-resistant organism surveillance rectal swabs, and of sink drain, air, and faucet samples. All PA isolates underwent whole-genome sequencing. PA-HAI was defined using US National Healthcare Safety Network criteria. ICU-acquired PA was defined as PA isolated from specimens obtained ≥48 h after ICU admission in those with prior negative rectal swabs. Sink-to-patient PA transmission was defined as ICU-acquired PA with close genomic relationship to isolate(s) previously recovered from sinks in a room/bedspace occupied 3-14 days prior to collection date of the relevant patient specimen.

FINDINGS

Over ten months, 72 PA-HAIs occurred among 60/4263 admissions. The rate of PA-HAI was 2.40 per 1000 patient-ICU-days; higher in patients who were PA-colonized on admission. PA-HAI was associated with longer stay (median: 26 vs 3 days uninfected; P < 0.001) and contributed to death in 22/60 cases (36.7%). Fifty-eight admissions with ICU-acquired PA were identified, contributing 35/72 (48.6%) PA-HAIs. Four patients with five PA-HAIs (6.9%) had closely related isolates previously recovered from their room/bedspace sinks.

CONCLUSION

Nearly half of PA causing HAI appeared to be acquired in ICUs, and 7% of PA-HAIs were associated with sink-to-patient transmission. Sinks may be an under-recognized reservoir for HAIs.

The Impact of SARS-CoV-2 Pandemic on Antibiotic Prescriptions and Resistance in a University Hospital from Romania

This paper aimed to evaluate the effects of the COVID-19 pandemic on prescription rates and antibiotic resistance in a university hospital. A retrospective study was conducted on the medical records of patients admitted to the Bihor Emergency Clinical County Hospital in Romania in 2019 (pre-pandemic) and 2021 (during the pandemic period). We evaluated the antibiotic consumption index (ACI) and susceptibility rates. The overall percentage of antibiotic prescribing increased in 2021, while the total number of patients decreased. Genito-urinary, digestive, respiratory infections, heart diseases and wounds were the most common conditions for antibiotic prescriptions, but the number of them decreased in 2021. There was a decrease in the proportion of antibiotics from the Watch and Reserve class and an increase in the proportion of antibiotics from the Access class. Antibiotic use has been reduced despite an increase in the number of patients, with a high consumption in the Watch group in the ICU wards. By contrast, surgical wards had the highest rate of antibiotic prescriptions, but a decrease in the number of patients. The patients who were administered antibiotics were hospitalized for diagnoses other than COVID-19. Almost all prescribed antibiotics displayed decreasing sensitivity rates. The number of isolated ESKAPE pathogens, except for Staphylococcus aureus methicillin-resistant strains, were increased. Strategies to control antibiotic prescriptions and the spread of resistant pathogens should be improved.

Modelling lung infection with Klebsiella pneumoniae after murine traumatic brain injury

Pneumonia is a common comorbidity in patients with severe traumatic brain injury (TBI), and is associated with increased morbidity and mortality. In this study, we established a model of intratracheal Klebsiella pneumoniae administration in young adult male and female mice, at 4 days following an experimental TBI, to investigate how K. pneumoniae infection influences acute post-TBI outcomes. A dose-response curve determined the optimal dose of K. pneumoniae for inoculation (1 x 10^6 colony forming units), and administration at 4 days post-TBI resulted in transient body weight loss and sickness behaviors (hypoactivity and acute dyspnea). K. pneumoniae infection led to an increase in pro-inflammatory cytokines in serum and bronchoalveolar lavage fluid at 24 h post-infection, in both TBI and sham (uninjured) mice. By 7 days, when myeloperoxidase + neutrophil numbers had returned to baseline in all groups, lung histopathology was observed with an increase in airspace size in TBI + K. pneumoniae mice compared to TBI + vehicle mice. In the brain, increased neuroinflammatory gene expression was observed acutely in response to TBI, with an exacerbated increase in Ccl2 and Hmox1 in TBI + K. pneumoniae mice compared to either TBI or K. pneumoniae alone. However, the presence of neuroinflammatory immune cells in the injured brain, and the extent of damage to cortical and hippocampal brain tissue, was comparable between K. pneumoniae and vehicle-treated mice by 7 days. Examination of the fecal microbiome across a time course did not reveal any pronounced effects of either injury or K. pneumoniae on bacterial diversity or abundance. Together, these findings demonstrate that K. pneumoniae lung infection after TBI induces an acute and transient inflammatory response, primarily localized to the lungs with some systemic effects. However, this infection had minimal impact on secondary injury processes in the brain following TBI. Future studies are needed to evaluate the potential longer-term consequences of this dual-hit insult.

Overcoming Therapeutic Challenges of Antibiotic Delivery with Cubosome Lipid Nanocarriers

Low discovery rates for new antibiotics, commercial disincentives to invest, and inappropriate use of existing drugs have created a perfect storm of antimicrobial resistance (AMR). This "silent pandemic" of AMR looms as an immense, global threat to human health. In tandem, many potential novel drug candidates are not progressed due to elevated hydrophobicity, which may result in poor intracellular internalization and undesirable serum protein binding. With a reducing arsenal of effective antibiotics, enabling technology platforms that improve the outcome of treatments, such as repurposing existing bioactive agents, is a prospective option. Nanocarrier (NC) mediated drug delivery is one avenue for amplifying the therapeutic outcome. Here, the performance of several antibiotic classes encapsulated within the lipid-based cubosomes is examined. The findings demonstrate that encapsulation affords significant improvements in drug concentration:inhibition outcomes and assists in other therapeutic challenges associated with internalization, enzyme degradation, and protein binding. We emphasize that a currently sidelined compound, novobiocin, became active and revealed a significant increase in inhibition against the pathogenic Gram-negative strain, Pseudomonas aeruginosa. Encapsulation affords co-delivery of multiple bioactives as a strategy for mitigating failure of monotherapies and tackling resistance. The rationale in optimized drug selection and nanocarrier choice is examined by transport modeling which agrees with experimental inhibition results. The results demonstrate that lipid nanocarrier encapsulation may alleviate a range of challenges faced by antibiotic therapies and increase the range of antibiotics available to treat bacterial infections.

PAM-1: an antimicrobial peptide with promise against ceftazidime-avibactam resistant Escherichia coli infection

Introduction

Antibiotic misuse and overuse have led to the emergence of carbapenem-resistant bacteria. The global spread of resistance to the novel antibiotic combination ceftazidime-avibactam (CZA) is becoming a severe problem. Antimicrobial peptide PAM-1 offers a novel approach for treating infections caused by antibiotic-resistant bacteria. This study explores its antibacterial and anti-biofilm activities and mechanisms against CZA-resistant Escherichia. Coli (E. coli), evaluating its stability and biosafety as well.

Methods

The broth microdilution method, growth curve analysis, crystal violet staining, scanning electron microscopy, and propidium iodide staining/N-phenyl-1-naphthylamine uptake experiments were performed to explore the antibacterial action and potential mechanism of PAM-1 against CZA-resistant E. coli. The biosafety in diverse environments of PAM-1 was evaluated by red blood cell hemolysis, and cytotoxicity tests. Its stability was further assessed under different temperatures, serum concentrations, and ionic conditions using the broth microdilution method to determine its minimum inhibitory concentration (MIC). Galleria mellonella infection model and RT-qPCR were used to investigate the in vivo antibacterial and anti-inflammatory effects.

Results and discussion

In vitro antibacterial experiments demonstrated that the MICs of PAM-1 ranged from 2 to 8 μg/mL, with its effectiveness sustained for a duration of 24 h. PAM-1 exhibited significant antibiofilm activities against CZA-resistant E. coli (p < 0.05). Furthermore, Membrane permeability test revealed that PAM-1 may exert its antibacterial effect by disrupting membrane integrity by forming transmembrane pores (p < 0.05). Red blood cell hemolysis and cytotoxicity tests revealed that PAM-1 exerts no adverse effects at experimental concentrations (p < 0.05). Moreover, stability tests revealed its effectiveness in serum and at room temperature. The Galleria mellonella infection model revealed that PAM-1 can significantly improve the survival rate of Galleria mellonella (>50%)for in vivo treatment. Lastly, RT-qPCR revealed that PAM-1 downregulates the expression of inflammatory cytokines (p < 0.05). Overall, our study findings highlight the potential of PAM-1 as a therapeutic agent for CZA-resistant E. coli infections, offering new avenues for research and alternative antimicrobial therapy strategies.

Efficacy and safety of antibiotics targeting Gram-negative bacteria in nosocomial pneumonia: a systematic review and Bayesian network meta-analysis

BACKGROUND

Multiple randomized controlled studies have compared numerous antibiotic regimens, including new, recently commercialized antibiotics in the treatment of nosocomial pneumonia (NP). The objective of this Bayesian network meta-analysis (NMA) was to compare the efficacy and the safety of different antibiotic treatments for NP.

METHODS

We conducted a systematic search of PubMed, Medline, Web of Science, EMBASE and the Cochrane Library databases from 2000 through 2021. The study selection included studies comparing antibiotics targeting Gram-negative bacilli in the setting of NP. The primary endpoint was 28 day mortality. Secondary outcomes were clinical cure, microbiological cure and adverse events.

RESULTS

Sixteen studies encompassing 4993 patients were included in this analysis comparing 13 antibiotic regimens. The level of evidence for mortality comparisons ranged from very low to moderate. No significant difference in 28 day mortality was found among all beta-lactam regimens. Only the combination of meropenem plus aerosolized colistin was associated with a significant decrease of mortality compared to using intravenous colistin alone (OR = 0.43; 95% credible interval [0.17-0.94]), based on the results of the smallest trial included. The clinical failure rate of ceftazidime was higher than meropenem with (OR = 1.97; 95% CrI [1.19-3.45]) or without aerosolized colistin (OR = 1.40; 95% CrI [1.00-2.01]), imipemen/cilastatin/relebactam (OR = 1.74; 95% CrI [1.03-2.90]) and ceftazidime/avibactam (OR = 1.48; 95% CrI [1.02-2.20]). For microbiological cure, no substantial difference between regimens was found, but ceftolozane/tazobactam had the highest probability of being superior to comparators. In safety analyses, there was no significant difference between treatments for the occurrence of adverse events, but acute kidney failure was more common in patients receiving intravenous colistin.

CONCLUSIONS

This network meta-analysis suggests that most antibiotic regimens, including new combinations and cefiderocol, have similar efficacy and safety in treating susceptible Gram-negative bacilli in NP. Further studies are necessary for NP caused by multidrug-resistant bacteria. Registration PROSPERO CRD42021226603.

Biofilm exopolysaccharides alter sensory-neuron-mediated sickness during lung infection

Infections of the lung cause observable sickness thought to be secondary to inflammation. Signs of sickness are crucial to alert others via behavioral-immune responses to limit contact with contagious individuals. Gram-negative bacteria produce exopolysaccharide (EPS) that provides microbial protection; however, the impact of EPS on sickness remains uncertain. Using genome-engineered Pseudomonas aeruginosa (P. aeruginosa) strains, we compared EPS-producers versus non-producers and a virulent Escherichia coli (E. coli) lung infection model in male and female mice. EPS-negative P. aeruginosa and virulent E. coli infection caused severe sickness, behavioral alterations, inflammation, and hypothermia mediated by TLR4 detection of the exposed lipopolysaccharide (LPS) in lung TRPV1+ sensory neurons. However, inflammation did not account for sickness. Stimulation of lung nociceptors induced acute stress responses in the paraventricular hypothalamic nuclei by activating corticotropin-releasing hormone neurons responsible for sickness behavior and hypothermia. Thus, EPS-producing biofilm pathogens evade initiating a lung-brain sensory neuronal response that results in sickness.

A Lignin Silver Nanoparticles/Polyvinyl Alcohol/Sodium Alginate Hybrid Hydrogel with Potent Mechanical Properties and Antibacterial Activity

Antibacterial hydrogels have attracted significant attention due to their diverse applications, efficient antimicrobial properties, and adaptability to various environments and requirements. However, their relatively fragile structure, coupled with the potential for environmental toxicity when exposed to their surroundings for extended periods, may significantly limit their practical application potential. In this work, a composite hydrogel was synthesized with outstanding mechanical features and antibacterial capability. The hydrogel was developed through the combination of the eco-friendly and enduring antibacterial agent, lignin silver nanoparticles (Lig-Ag NPs), with polyvinyl alcohol (PVA) and sodium alginate (SA), in varying proportions. The successful synthesis of the hydrogel and the dispersed distribution of Lig-Ag NPs within the hydrogel were confirmed by various analytical techniques, including field emission scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), mercury intrusion porosimetry (MIP), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The formation of multiple hydrogen bonds between Lig-Ag NPs and the composites contributed to a more stable and dense network structure of the hydrogel, consequently enhancing its mechanical properties. Rheological tests revealed that the hydrogel exhibited an elastic response and demonstrated outstanding self-recovery properties. Significantly, the antibacterial hydrogel demonstrated effectiveness against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), achieving a <5% survival of bacteria within 12 h. This study presented a green and straightforward synthetic strategy for the application of antibacterial composite hydrogels in various fields.

Genotypic and phenotypic mechanisms underlying antimicrobial resistance and synergistic efficacy of rifampicin-based combinations against carbapenem-resistant Acinetobacter baumannii

Purpose

Carbapenem-resistant Acinetobacter baumannii (CRAB) is an urgent concern to public health. This study focuses on exploring the resistance mechanisms and the in vitro results of using rifampicin in combination with conventional antibiotics for the management of CRAB.

Methods

The synergistic and bactericidal effects of rifampicin with conventional antibiotics were evaluated using chequerboard assay and time-kill assay, while the phenotypic and genotypic characteristics of resistant determinants were performed by efflux pump detection and whole genome sequencing on 29 isolates from ICU patients with underlying health diseases.

Results

The isolates showed multidrug resistance, with over 60% showing addictive responses to rifampicin-based combinations at FICI ranging from 0.6 to 0.8. The time-kill assay revealed 99 % killing for rifampicin and minocycline combination in one isolate at 1/4 MIC rifampicin plus 1/4 MIC minocycline, while a bacteriostatic effect was observed at 1/2 MIC rifampici plus 1/2 MIC for a second isolate. Combination with tigecycline resulted in a 99% killing in two out of three isolates with a 2.5-3 log reduction in CFU at 1/4 MIC rifampicin plus 1/4 MIC tigecycline. Rifampicin plus colistin exhibited bactericidal activity against three out of four isolates. The combinations of rifampicin with ciprofloxacin, chloramphenicol, and trimethoprim-sulfamethoxazole were ineffective against the isolates. In addition, a 4-fold reduction in rifampicin MIC was observed in 2 out of 14 isolates in the presence of an efflux pump inhibitor. The pan-genome study demonstrated a progressive evolution with an accessory genome estimated to cover 58% of the matrix. Seven of the ten sequenced isolates belong to sequence type 2 (ST2), while one isolate each was assigned to ST164, ST16, and ST25. Furthermore, 11 plasmids, 34 antimicrobial resistance (AMR) genes, and 65 virulence-associated genes were predicted from the whole genome data. The blaOXA-23blaADC-25, blaOXA-66, blaPER-7, aph(6)-Id, armA, and arr-3 were prevalent among the isolates. Sequence alignment of the bacteria genome to the reference strain revealed a deleterious mutation in the rpoB gene of 4 isolates.

Conclusion

The study suggests that rifampicin in combination with either minocycline, tigecycline, or colistin might be a treatment option for CRAB clinical isolates. In addition, genotypic analysis of the bacteria isolates may inform the clinician of the suitable drug regimen for the management of specific bacteria variants.

Clinically used broad-spectrum antibiotics compromise inflammatory monocyte-dependent antibacterial defense in the lung

Hospital-acquired pneumonia (HAP) is associated with high mortality and costs, and frequently caused by multidrug-resistant (MDR) bacteria. Although prior antimicrobial therapy is a major risk factor for HAP, the underlying mechanism remains incompletely understood. Here, we demonstrate that antibiotic therapy in hospitalized patients is associated with decreased diversity of the gut microbiome and depletion of short-chain fatty acid (SCFA) producers. Infection experiments with mice transplanted with patient fecal material reveal that these antibiotic-induced microbiota perturbations impair pulmonary defense against MDR Klebsiella pneumoniae. This is dependent on inflammatory monocytes (IMs), whose fatty acid receptor (FFAR)2/3-controlled and phagolysosome-dependent antibacterial activity is compromized in mice transplanted with antibiotic-associated patient microbiota. Collectively, we characterize how clinically relevant antibiotics affect antimicrobial defense in the context of human microbiota, and reveal a critical impairment of IM´s antimicrobial activity. Our study provides additional arguments for the rational use of antibiotics and offers mechanistic insights for the development of novel prophylactic strategies to protect high-risk patients from HAP.

Device-Associated Infections in COVID-19 Patients: Frequency of Resistant Bacteria, Predictors and Mortality in Medellín, Colombia

INTRODUCTION

Increased antimicrobial use during the COVID-19 pandemic has raised concerns about the spread of resistant bacteria. This study analyzed the frequency of device-associated infections (DAI) caused by resistant bacteria, the predictors of these infections, and 30-day all-cause mortality in patients with and without COVID-19.

METHODS

A retrospective cohort study was conducted on DAI patients admitted to the ICU (intensive care unit) in 20 hospitals in Medellin, Colombia (2020-2021). The exposure assessed was the COVID-19 diagnosis, and outcomes analyzed were resistant bacterial infections and 30-day mortality. Clinical and microbiological information was collected from surveillance databases. Statistical analysis included generalized linear mixed-effects models.

RESULTS

Of the 1521 patients included, 1033 (67.9%) were COVID-19-positive and 1665 DAI were presented. Carbapenem-resistant Enterobacteriaceae (CRE) infections predominated during the study (n = 98; 9.9%). The patients with COVID-19 had a higher frequency of metallo-beta-lactamase-producing CRE infections (n = 15; 33.3%) compared to patients without the disease (n = 3; 13.0%). Long-stay in the ICU (RR: 2.09; 95% CI: 1.39-3.16), diabetes (RR: 1.73; 95% CI: 1.21-2.49), and mechanical ventilation (RR: 2.13; 95% CI: 1.01-4.51) were CRE infection predictors in COVID-19 patients, with a mortality rate of 60.3%.

CONCLUSION

CRE infections were predominant in COVID-19 patients. In pandemic situations, the strategies to control DAI should be maintained to avoid infections caused by resistant bacteria, such as length of stay in the ICU and duration of mechanical ventilation.

Comparing prolonged infusion to intermittent infusion strategies for beta-lactam antibiotics in patients with gram-negative bacterial infections: a systematic review and meta-analysis

INTRODUCTION

Our objective is to determine whether prolonged infusion (PI) of beta-lactam antibiotics yields superior outcomes compared to intermittent infusion (II) in patients with Gram-Negative Bacterial (GNB) infections.

METHODS

We systematically searched papers from PubMed, the Cochrane Library, Embase, and Clinicaltrials.gov, targeting mortality as the primary outcome and looking at the clinical cure rate, hospital and intensive care unit (ICU) stay lengths, antibiotic treatment duration, and mechanical ventilation (MV) duration as secondary outcomes.

RESULTS

Our meta-analysis of 18 studies, including 5 randomized control trials and 13 observational studies, with a total of 3,035 patients-1,510 in the PI group and 1,525 in the II group, revealed significant findings. PI was associated with reduced mortality (RR, 0.67; 95% CI, 0.55-0.81; p = 0.001; I2 = 4.52%) and a shorter MV duration (SMD, -0.76; 95% CI, -1.37 to -0.16; p = 0.01; I2 = 87.81%) compared to II. However, no differences were found in clinical cure rates, antibiotic treatment duration, length of hospital stay, or length of ICU stay.

CONCLUSIONS

The PI approach for administering beta-lactam antibiotics in patients with suspected or confirmed GNB infections may be advantageous in reducing mortality rates and the duration of MV when compared to the II strategy.

Mechanism exploration of SanShi ShengXin Ointment in the treatment of pressure ulcers based on network pharmacology and molecular docking

BACKGROUND

To explore the active ingredients, prospective targets, and action mechanisms of SanShi ShengXin Ointment in the treatment of pressure ulcers (PU) based on the network pharmacology technique and molecular docking technology.

METHODS

The active ingredients and action targets of Sanshishengxin Ointment were searched through the Traditional Chinese Medicine Systematic Pharmacology Database and Analysis Platform. The PU-related targets were retrieved from the GeneCards and DisGeNET databases. The intersection target genes of disease and drugs were obtained. The "disease-drug-active ingredient-target" was constructed using Cytoscape software. The intersection target genes were imported into the String database to construct a protein-protein interaction network for gene ontology and Kyoto Encyclopedia of Genes and Genomes analyses. The Auto Dock software was used for relevant molecular docking.

RESULTS

A total of 78 active ingredients of SanShi ShengXin Ointment were obtained, corresponding to 539 target genes. There were 5896 PU-related target genes, and 373 intersection target genes of disease and drugs were obtained, such as STAT3, TP53, JUN, MAPK3, CTNNB1, involving PI3K-Akt, TNF, MAPK, and other related signaling pathways.

CONCLUSION

Based on network pharmacology and molecular docking analyses, this study demonstrates that SanShi ShengXin Ointment can treat PU through multicomponent, multitarget, and multipathway. .

Antimicrobial efficacy of eravacycline against emerging extensively drug-resistant (XDR) Acinetobacter baumannii isolates

PURPOSE

Drug-resistant Acinetobacter baumannii is an emerging threat. This study has been conducted to observe the efficacy of eravacycline along with the RND-efflux pump system.

METHODS

A cross-sectional study was done collecting 48 clinical isolates of Acinetobacter baumannii. MICs of 15 antibiotics were detected along with BMD of tigecycline and eravacycline. PCR products of drug-resistant regulatory genes were sequenced and analyzed.

RESULTS

Of the total 48 Isolates, 35 (72.91%) were XDR and 13 (27.08%) were MDR. Out of all, 60.41% of isolates were found to be susceptible to eravacycline by BMD according to both FDA and EUCAST guidelines. A 2-fold decline of MIC50/90 was observed with the use of eravacycline compared to tigecycline. RND-efflux genes like AdeC in 30 (62.5%) isolates and Regulatory gene AdeS in 29 (60.41%) isolates were detected, explaining the existing resistance mechanism.

CONCLUSIONS

XDR Acinetobacter poses an escalating threat due to its resistance to multiple antibiotics, raising serious concerns in healthcare settings. Eravacycline is an encouraging new drug for empirical use in severe infection caused due to the same. Molecular investigation and strict antimicrobial stewardship should be followed to control the emergence, and a better understanding of mechanisms of resistance to prevent the spread of drug-resistant isolates.

The Global and Regional Prevalence of Hospital-Acquired Carbapenem-Resistant Klebsiella pneumoniae Infection: A Systematic Review and Meta-analysis

Background

Due to scarce therapeutic options, hospital-acquired infections caused by Klebsiella pneumoniae (KP), particularly carbapenem-resistant KP (CRKP), pose enormous threat to patients' health worldwide. This study aimed to characterize the epidemiology and risk factors of CRKP among nosocomial KP infections.

Method

MEDLINE, Embase, PubMed, and Google Scholar were searched for studies reporting CRKP prevalence from inception to 30 March 2023. Data from eligible publications were extracted and subjected to meta-analysis to obtain global, regional, and country-specific estimates. To determine the cause of heterogeneity among the selected studies, prespecified subgroup analyses and meta-regression were also performed. Odds ratios of CRKP-associated risk factors were pooled by a DerSimonian and Laird random-effects method.

Results

We retained 61 articles across 14 countries and territories. The global prevalence of CRKP among patients with KP infections was 28.69% (95% CI, 26.53%-30.86%). South Asia had the highest CRKP prevalence at 66.04% (95% CI, 54.22%-77.85%), while high-income North America had the lowest prevalence at 14.29% (95% CI, 6.50%-22.0%). In the country/territory level, Greece had the highest prevalence at 70.61% (95% CI, 56.77%-84.45%), followed by India at 67.62% (95% CI, 53.74%-81.79%) and Taiwan at 67.54% (95% CI, 58.65%-76.14%). Hospital-acquired CRKP infections were associated with the following factors: hematologic malignancies, corticosteroid therapies, intensive care unit stays, mechanical ventilations, central venous catheter implantations, previous hospitalization, and antibiotic-related exposures (antifungals, carbapenems, quinolones, and cephalosporins).

Conclusions

Study findings highlight the importance of routine surveillance to control carbapenem resistance and suggest that patients with nosocomial KP infection have a very high prevalence of CRKP.

Meropenem plus Ertapenem and Ceftazidime-Avibactam plus Aztreonam for the Treatment of Ventilator Associated Pneumonia Caused by Pan-Drug Resistant Klebsiella pneumonia

INTRODUCTION

Gram-negative bacteria (GNB) account for about 70% of infections in the intensive care unit (ICU) setting and are associated with significant morbidity and mortality. In recent years, pan-drug resistant (PDR) strains, strains that are not susceptible to any antibiotic, have been emerged and new treatment strategies are required.

RESULTS

Fifty eligible patients were recruited in the three groups. A statistically significant reduction in the Sequential Organ Failure Assessment (SOFA) score was observed in the control group on day 4 in comparison to day 0 of VAP (p = 0.005). The Clinical Pulmonary Infection Score (CPIS) was also reduced on day 4 (p = 0.0016) and day 7 in comparison to day 0 (p = 0.001). Patients that received combination therapy, CAZ-AVI + ATM and DCT, presented with a lower SOFA score and CPIS on day 7 in comparison to day 0 (p = 0.0288 and p = 0.037, respectively). No differences in the ΔSOFA score and ΔCPIS were found between the groups. The control group presented with a significantly lower ICU stay and duration of mechanical ventilation (p = 0.03 and p = 0.02, respectively). There was no difference in mortality.

MATERIALS AND METHODS

This is a retrospective analysis. This study was conducted in a mixed ICU in the University Hospital of Larissa, Thessaly, Greece during a three-year period (2020-2022). Patients suffering from ventilator associated pneumonia (VAP) due to carbapenem-resistant K. pneumonia (CR-KP) were divided in three different groups: the first one was treated using ceftazidime-avibactam plus aztreonam (CAZ-AVI + ATM group), the second was treated using double carbapenems (DCT group), and the last one (control group) received appropriate therapy since the strain was susceptible in vitro to at least to one antibiotic.

CONCLUSIONS

Treatment with CAZ-AVI +ATM or DCT may offer a clinical benefit in patients suffering with infections due to PDR K. pneumoniae. Larger studies are required to confirm our findings.

Polymeric coating doped with nanomaterials for functional impact on different substrates

Microorganism contamination on substrate surfaces is arousing increasingly concern as a serious health issue. In this research work, antimicrobial water-based acrylic paint containing silver nanoparticles (Ag NPs) was prepared using the facile Ag+ in situ reduction process, in which AgNO3 and reducing agent sodium acrylate were refluxed with acrylic polymeric solution to obtain an antimicrobial and antifungal polymeric material for substrate coating. The Synthesized antimicrobial and antifungal water-based acrylic paint were characterized by different spectroscopic techniques. The FTIR and UV-Visible spectroscopic analyses were investigated to study the water-based acrylic paint structure as well as the significant impact of Ag NPs on the paint matrix. The UV-Visible and FTIR Spectra peak shows successful integration of Ag NPs within the polymer matrix without altering the core functional groups of the paint. The water based acrylic paint exhibited a strong antimicrobial activity, revealed substantial inhibition zones against all four strains of Gram negative represented by Escherichia coli, Acinetobacter baumannii, Klebsiella pneumoniae and Gram-positive represented by Bacillus cereus. The coated film on substrate also shows great inhibition zone which exhibit a strong antimicrobial activity. Moreover, water based acrylic paint also exhibited a great antifungal activity, revealed substantial zone of inhibition against the Aspergillus niger, Aspergillus terreus and Rhizopus arrhizus fungal strains. Also, the coated film showed the best adhesion at 50% and 80% solution of polymeric coating sample as compared to pure or very dilute sample coating. This innovative approach has the potential to revolutionize varies industries from healthcare to construction.

Upregulation of PTPN1 aggravates endotoxemia-induced cardiac dysfunction through inhibiting mitophagy

OBJECTIVES

To investigate the role of protein tyrosine phosphatase non-receptor type 1 (PTPN1) in mitophagy during sepsis and its underlying mechanisms and determine the therapeutic potential of PTPN1 inhibitors in endotoxemia-induced cardiac dysfunction.

METHODS

A mouse model of endotoxemia was established by administering an intraperitoneal injection of lipopolysaccharide (LPS). The therapeutic effect of targeting PTPN1 was evaluated using its inhibitor Claramine (CLA). Mitochondrial structure and function as well as the expression of mitophagy-related proteins were evaluated. Rat H9c2 cardiomyocytes were exposed to mouse RAW264.7 macrophage-derived conditioned medium. Cryptotanshinone, a specific p-STAT3 (Y705) inhibitor, was used to confirm the role of STAT3 in PTPN1-mediated mitophagy following LPS exposure. Electrophoretic mobility shift and dual luciferase reporter assays were performed to discern the mechanisms by which STAT3 regulated the expression of PINK1 and PRKN.

RESULTS

CLA alleviated LPS-induced myocardial damage, cardiac dysfunction, and mitochondrial injury and dysfunction in the mouse heart. PTPN1 upregulation exacerbated LPS-induced mitochondrial injury and dysfunction in H9c2 cardiomyocytes, but inhibited LPS-induced mitophagy. LPS promoted the interaction between PTPN1 and STAT3 and reduced STAT3 phosphorylation at Tyr705 (Y705), which was required to inhibit mitophagy by PTPN1. Upon LPS stimulation, PTPN1 negatively regulated the transcription of PINK1 and PRKN through dephosphorylation of STAT3 at Y705. STAT3 regulated the transcription of PINK1 and PRKN by binding to STAT3-responsive elements in their promoters.

CONCLUSION

PTPN1 upregulation aggravates endotoxemia-induced cardiac dysfunction by impeding mitophagy through dephosphorylation of STAT3 at Y705 and negative regulation of PINK1 and PRKN transcription.

Boron Compound-Based Treatments Against Multidrug-Resistant Bacterial Infections in Lung Cancer In Vitro Model

Multidrug-resistant bacteria is one of the most important public health problems. Increasing rates of antibacterial resistance also affect the outcomes of medical approaches. Cancer treatment because of immune system deficiency (chemotherapy or steroids usage) commonly can cause infection. Lung cancer is the dominant cause of cancer-related deaths, and infection is the most common cause of death among those patients. In this study, it was aimed to determine the antimicrobial, antibiofilm, and anticancer activity of boron compounds. A549 lung cancer cell line was infected with Acinetobacter baumannii (ATCC 19606), Klebsiella pneumoniae (ATCC 700603), and Pseudomonas aeruginosa (ATCC 27853). In order to determine the fractional inhibitory concentration (FIC) index, antibiotics and boron compound concentrations prepared according to the minimum inhibitory concentration (MIC) values were determined by the checkerboard method. In our study results, the antibiofilm activity was an average of 46% in A. baumannii+boron compounds, 45% in P. aeruginosa+boron compounds, and 43% in K. pneumoniae. Cell culture analysis results show a decrease in viability and antioxidant capacity and an increase in total oxidant status after adding boron compounds to the culture. Immunofluorescence results show a correlation with MTT, and boron compounds increased 8-OHdG expression in comparison to antibiotic administration. In conclusion, boron compounds have promising effects on bacteria, especially in resistant bacteria spp.

Antibacterial Activity of Boron Compounds Against Biofilm-Forming Pathogens

This study aimed to evaluate the antibacterial activity of nine boron derivatives against biofilm-forming pathogenic bacteria. The effect of boron derivatives (CMB, calcium metaborate; SMTB, sodium metaborate tetrahydrate; ZB, zinc borate; STFB, sodium tetra fluorine borate; STB, sodium tetraborate; PTFB, potassium tetra fluor borate; APTB, ammonium pentabo-rate tetrahydrate; SPM, sodium perborate monohydrate; Borax, ATFB, ammonium tetra fluorine borate) on bacteria isolated from blood culture was determined by the minimum inhibitory concentration (MIC) method. Then, biofilm formation potentials on microplates, tubes, and Congo red agar were examined. The cytotoxicity of boron derivatives was determined by using WST-1-based methods. The interaction between the biofilm-forming bacteria, fibroblast cells, and boron derivatives was determined with the infection model. We found that the sodium metaborate tetrahydrate molecule was effective against all pathogens. According to the optical density values detected at 630 nm in microplates, meticillin-resistant Staphylococcus aureus was observed to have the most substantial biofilm ability at 0.257 nm. As a result of cytotoxicity studies, it has been determined that a 1 µg/L concentration of boron derivatives is not toxic to fibroblast L929 cells. In cell culture experiments, these boron derivatives have very serious inhibitory activity against biofilm-forming pathogens in a short treatment period, such as 2-4 h. Furthermore, using these molecules on inanimate surfaces affected by biofilms would be appropriate instead of living cells.

Role of the Bacterial Amyloid-like Hfq in Fluoroquinolone Fluxes

Due to their two-cell membranes, Gram-negative bacteria are particularly resistant to antibiotics. Recent investigations aimed at exploring new target proteins involved in Gram-negative bacteria adaptation helped to identify environmental changes encountered during infection. One of the most promising approaches in finding novel targets for antibacterial drugs consists of blocking noncoding RNA-based regulation using the protein cofactor, Hfq. Although Hfq is important in many bacterial pathogens, its involvement in antibiotics response is still unclear. Indeed, Hfq may mediate drug resistance by regulating the major efflux system in Escherichia coli, but it could also play a role in the influx of antibiotics. Here, using an imaging approach, we addressed this problem quantitatively at the single-cell level. More precisely, we analyzed how Hfq affects the dynamic influx and efflux of ciprofloxacin, an antibiotic from the group of fluoroquinolones that is used to treat bacterial infections. Our results indicated that the absence of either whole Hfq or its C-terminal domain resulted in a more effective accumulation of ciprofloxacin, irrespective of the presence of the functional AcrAB-TolC efflux pump. However, overproduction of the MicF small regulatory RNA, which reduces the efficiency of expression of the ompF gene (coding for a porin involved in antibiotics influx) in a Hfq-dependent manner, resulted in impaired accumulation of ciprofloxacin. These results led us to propose potential mechanisms of action of Hfq in the regulation of fluoroquinolone fluxes across the E. coli envelope.

Distribution and antimicrobial resistance analysis of gram-negative bacilli isolated from a tertiary hospital in Central China: a 10-year retrospective study from 2012 to 2021

Background

Gram-negative bacilli are one of the most common causes of various infections in clinical. The emergence and global spread of multi-drug resistant gram-negative bacilli has become a major challenge in the global public health field.

Methods

A total of 51,189 non-repetitive strains of gram-negative bacilli were isolated in clinical settings. The antimicrobial susceptibility testing was conducted by using the automated VITEK 2 compact system and the matched AST susceptibility test card, complemented by the disk diffusion method. The antimicrobial susceptibility results were interpreted by CLSI. Rates of MDR and XDR in Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa were investigated. Used the chi-square test to determine whether the antimicrobial resistance rates of four major gram-negative bacilli isolated from ICU and non-ICU department have statistical differences.

Results

Escherichia coli (31.4%), Klebsiella spp. (21.2%), Acinetobacter spp. (13.8%), and P. aeruginosa (11.0%) were the most frequently isolated gram-negative bacilli. Escherichia coli was the top one organism isolated from urinary tract (68.4%), bloodstream (39.9%), body fluid (33.2%), wound and pus (37%), except for respiratory tract (8.8%). Whereas Acinetobacter baumannii and K. pneumoniae were the major isolated organisms from respiratory tract. Acinetobacter baumannii showed high resistance to fluoroquinolones, β-lactam/β-lactamase inhibitor combinations class, ceftazidime, cefepime, imipenem, and meropenem, the resistance rates reached more than 70%. Ceftazidime showed a lower resistance rate to E. coli than ceftriaxone. For E. coli, fluoroquinolones showed a high resistance rate (ciprofloxacin 61.36% and levofloxacin 53.97%), whereas amikacin, carbapenems exhibited a lower resistance rate fluctuating at 2%. Acinetobacter baumannii and K. pneumoniae showed rapid increases in carbapenem resistance whereas E. coli had the lowest resistance rate and remain stable at 2%. Acinetobacter baumannii exhibited the highest rate of MDR and XDR, reaching 60-80 and 45-55%, respectively. Compared to non-ICU departments, the resistance rates of four major gram-negative bacilli in the ICU department were much higher and the differences were statistically significant (p < 0.05).

Conclusion

Amikacin, carbapenems, and piperacillin/tazobactam exhibited relatively high sensitivity, whereas fluoroquinolones showed high resistance rate whether they can be the first-line antimicrobials for empirical treatment of UTI should take more consideration. The gram-negative bacilli in ICU were more resistance than that in non-ICU. These findings are helpful for clinicians using antimicrobials reasonably.

Inactivation of human coronaviruses using an automated room disinfection device

The emergence of more virulent and epidemic strains of viruses, especially in the context of COVID-19, makes it more important than ever to improve methods of decontamination. The objective of this study was to evaluate the potential of on-demand production of chlorine species to inactivate human coronaviruses. The commercial prototype disinfection unit was provided by Unipolar Water Technologies. The Unipolar device generates active chlorine species using an electrochemical reaction and dispenses the disinfectant vapour onto surfaces with an aspirator. The minimum effective concentration and exposure time of disinfectant were evaluated on human hepatoma (Huh7) cells using 50% tissue culture infectious dose (TCID50) assay and human coronavirus 229E (HCoV-229E), a surrogate for pathogenic human coronaviruses. We showed that chlorine species generated in the Unipolar device inactivate HCoV-229E on glass surfaces at ≥ 400 parts per million active chlorine concentration with a 5 min exposure time. Here, inactivation refers to the inability of the virus to infect the Huh7 cells. Importantly, no toxic effect was observed on Huh7 cells for any of the active chlorine concentrations and contact times tested.

Sustainable preparation of luminescent carbon dots from syringe waste and hyaluronic acid for cellular imaging and antimicrobial applications

Addressing the global challenge of persistent waste through an eco-conscious strategy to transform it into valuable and versatile materials holds great significance in today's swiftly evolving world. By adopting a sustainable approach, we can repurpose waste syringes composed of polytetrafluoroethylene (PTFE) into fluorescent carbon dots (CDs) using a simple hydrothermal process. This research harnessed hyaluronic acid to carbonize and modify discarded plastic syringes, resulting in the creation of luminescent syringe carbon dots (SCDs). Rigorous analysis employing diverse techniques delved into their optical attributes, size distribution, and surface characteristics. Extensive biocompatibility assessments using established assay methods confirmed the safety of the derived SCDs, unveiling their potential antibacterial and antifungal traits. Additionally, a confocal microscope was employed to evaluate the cellular imaging capabilities of SCDs on HeLa cells. Notably, at bactericidal concentrations, SCDs exhibited mild cytotoxicity towards mammalian cells, showcasing cell viability surpassing 91.07% at 1 mg/mL. This pioneering exploration paves the way for potential applications of SCD-based nano-bactericides across various biomedical domains. The initial outcomes established herein mark a significant stride towards the creation of cost-effective and ecologically sound fluorescent probes for biomedical imaging, aimed at combating microbial infections. By ingeniously reutilizing polyethylene terephthalate (PET), this investigation offers a sustainable remedy to address the ecological predicaments linked with plastic waste. In doing so, it charts a course towards contributing to the development of affordable, eco-friendly solutions, heralding a promising prospect for a cleaner, healthier environment.

Meropenem/Vaborbactam: β-Lactam/β-Lactamase Inhibitor Combination, the Future in Eradicating Multidrug Resistance

Due to the fact that there is a steadily increasing trend in the area of antimicrobial resistance in microorganisms, there is a need to look for new treatment alternatives. One of them is the search for new β-lactamase inhibitors and combining them with β-lactam antibiotics, with the aim of increasing the low-dose efficacy, as well as lowering the resistance potential of bacterial strains. This review presents the positive effect of meropenem in combination with a vaborbactam (MER-VAB). This latest antibiotic-inhibitor combination has found particular use in the treatment of infections with the etiology of carbapenem-resistant Enterobacterales (CRE), Gram-negative bacteria, with a high degree of resistance to available antimicrobial drugs.

Gallium-based metal-organic frameworks loaded with antimicrobial peptides for synergistic killing of drug-resistant bacteria

Increased antibiotic resistance has made bacterial infections a global concern, which requires novel non-antibiotic-dependent antibacterial strategies to address the menace. Antimicrobial peptides (AMPs) are a promising antibiotic alternative, whose antibacterial mechanism is mainly to destroy the membrane of bacteria. Gallium ions exhibit an antibacterial effect by interfering with the iron metabolism of bacteria. With the rapid development of nanotechnology, it is worth studying the potential of gallium-AMP-based nanocomposites for treating bacterial infections. Herein, novel gallium-based metal-organic frameworks (MOFs) were synthesized at room temperature, followed by in situ loading of the model AMP melittin. The obtained nanocomposites exhibited stronger antibacterial activity than pure MEL and gallium ions, achieving the effects of "one plus one is greater than two". Moreover, the nanocomposites showed favorable biocompatibility and accelerated healing of a wound infected by methicillin-resistant Staphylococcus aureus by down-regulation of inflammatory cytokines IL-6 and TNF-α. This work presents an innovative antibacterial strategy to overcome the antibiotic resistance crisis and expand the application of AMPs.

Customized cutoff limits for the sediMAX-2 automated analyzer reduce the number of urine culture tests

BACKGROUND

Urinary tract infections are highly prevalent in nosocomial and community settings. Their diagnosis, although costly and time-consuming, is crucial to avoid inappropriate treatments and/or clinical complications. In this context, automated analyzers have been developed and commercialized to screen and rule out negative urine samples. Adjustments of the manufacturers' suggested cutoff values might lead to substantial diagnostic and economic advantages.

METHODS

We retrospectively analyzed 776 urine samples from different individuals. 546 samples (training group) were used to optimize develop new cutoffs values. The remaining 230 samples (validation group) were used to validate the optimized cutoffs. All samples were subjected to urine culture, 17% resulted positive. Escherichia coli and Enterococcus faecalis were the two most frequently identified bacteria, 95 and 9 samples, respectively.

RESULTS

Two different cutoffs levels were obtained. Cutoff-A (bacteria>110 and/or white blood cells> 15 cell/µL), showed the same sensitivity of the manufacturers' suggested cutoff, yet leads to a large reduction of the samples to be cultured. Cutoff-B (bacteria>50 and/or white blood cells>20 cell/µL), showed an almost 100% sensitivity by subjecting only ~70% of the samples to urine culture.

CONCLUSION

Cutoff-A is a good compromise between sensitivity and specificity yet allowing economic advantages by reducing the number of urinary cultures. Cutoff-B relegates urinary tract infection misdiagnosis to a rare event without the need of culturing the entire batch of samples. We believe that clinical implementation of the proposed cutoffs will help other laboratories, using similar instrumentation, to reach their most convenient balance between sensitivity and economical needs.

The burden of hospital acquired infections and antimicrobial resistance

The burden of Hospital care-associated infections (HCAIs) is becoming a global concern. This is compounded by the emergence of virulent and high-risk bacterial strains such as "ESKAPE" pathogens - (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter species), especially within Intensive care units (ICUs) that house high-risk and immunocompromised patients. In this review, we discuss the contributions of AMR pathogens to the increasing burden of HCAIs and provide insights into AMR mechanisms, with a particular focus on last-resort antibiotics like polymyxins. We extensively discuss how structural modifications of surface-membrane lipopolysaccharides and cationic interactions influence and inform AMR, and subsequent severity of HCAIs. We highlight some bacterial phenotypic survival mechanisms against polymyxins. Lastly, we discuss the emergence of plasmid-mediated resistance as a phenomenon making mitigation of AMR difficult, especially within the ICUs. This review provides a balanced perspective on the burden of HCAIs, associated pathogens, implication of AMR and factors influencing emerging AMR mechanisms.

Biomimetic catheter surface with dual action NO-releasing and generating properties for enhanced antimicrobial efficacy

Infection of indwelling catheters is a common healthcare problem, resulting in higher morbidity and mortality. The vulnerable population reliant on catheters post-surgery for food and fluid intake, blood transfusion, or urinary incontinence or retention is susceptible to hospital-acquired infection originating from the very catheter. Bacterial adhesion on catheters can take place during the insertion or over time when catheters are used for an extended period. Nitric oxide-releasing materials have shown promise in exhibiting antibacterial properties without the risk of antibacterial resistance which can be an issue with conventional antibiotics. In this study, 1, 5, and 10 wt % selenium (Se) and 10 wt % S-nitrosoglutathione (GSNO)-incorporated catheters were prepared through a layer-by-layer dip-coating method to demonstrate NO-releasing and NO-generating capability of the catheters. The presence of Se on the catheter interface resulted in a 5 times higher NO flux in 10% Se-GSNO catheter through catalytic NO generation. A physiological level of NO release was observed from 10% Se-GSNO catheters for 5 d, along with an enhanced NO generation via the catalytic activity as Se was able to increase NO availability. The catheters were also found to be compatible and stable when subjected to sterilization and storage, even at room temperature. Additionally, the catheters showed a 97.02% and 93.24% reduction in the adhesion of clinically relevant strains of Escherichia coli and Staphylococcus aureus, respectively. Cytocompatibility testing of the catheter with 3T3 mouse fibroblast cells supports the material's biocompatibility. These findings from the study establish the proposed catheter as a prospective antibacterial material that can be translated into a clinical setting to combat catheter-related infections.

Biofilms exacerbate atherogenesis through macrophage-induced inflammatory responses in a fibrous plaque microsystem model

BACKGROUND

Microbes have been implicated in atherosclerosis development and progression, but the impact of bacterial-based biofilms on fibrous plaque rupture remains poorly understood.

RESULTS

Here, we developed a comprehensive atherosclerotic model to reflect the progression of fibrous plaque under biofilm-induced inflammation (FP-I). High expressions of biofilm-specific biomarkers algD, pelA and pslB validated the presence of biofilms. Biofilm promotes the polarization of macrophages towards a pro-inflammatory (M1) phenotype, as demonstrated by an increase in M1 macrophage-specific marker CD80 expression in CD68+ macrophages. The increase in the number of intracellular lipid droplets (LDs) and foam cell percentage highlighted the potential role of biofilms on lipid synthesis or metabolic pathways in macrophage-derived foam cells. In addition, collagen I production by myofibroblasts associated with the fibrous cap was significantly reduced along with the promotion of apoptosis of myofibroblasts, indicating that biofilms affect the structural integrity of the fibrous cap and potentially undermine its strength.

CONCLUSION

We validated the unique role of biofilm-based inflammation in exacerbating fibrous plaque damage in the FP-I model, increasing fibrous plaque instability and risk of thrombosis. Our results lay the foundation for mechanistic studies of the role of biofilms in fibrous plaques, allowing the evaluation of preclinical combination strategies for drug therapy.

STATEMENT OF SIGNIFICANCE

A microsystem-based model was developed to reveal interactions in fibrous plaque during biofilm-induced inflammation (FP-I). Real-time assessment of biofilm formation and its role in fibrous plaque progression was achieved. The presence of biofilms enhanced the expression of pro-inflammatory (M1) specific marker CD80, lipid droplets, and foam cells and reduced anti-inflammatory (M2) specific marker CD206 expression. Fibrous plaque exposure to biofilm-based inflammation reduced collagen I expression and increased apoptosis marker Caspase-3 expression significantly. Overall, we demonstrate the unique role of biofilm-based inflammation in exacerbating fibrous plaque damage in the FP-I model, promoting fibrous plaque instability and enhanced thrombosis risk. Our findings lay the groundwork for mechanistic studies, facilitating the evaluation of preclinical drug combination strategies.

Distribution of bacteria and risk factors in patients with multidrug-resistant pneumonia in a single center rehabilitation ward

Stroke patients may have dysphagia and frequent aspiration increasing exposure to antibiotics and the chance of multidrug-resistant (MDR) bacteria infection. This study investigated clinical risk factors and related antibiotic use of MDR bacteria infection in stroke patients in the rehabilitation ward, hoping that it can help prevent and reduce the condition of MDR bacteria. A retrospective cohort study was conducted using the database of stroke patients with pneumonia admitted to the rehabilitation ward from January 1, 2020, to June 30, 2022. The selected stroke patients were divided into the MDR and non-MDR groups. Analyze the infection bacteria of the 2 groups. Forward logistic regression was applied to identify possible independent MDR bacteria infection risk factors. A total of 323 patients were included. The top 3 common MDR pathogens were Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter baumannii. Almost all Pseudomonas aeruginosa and Acinetobacter baumannii are resistant to ertapenem. National Institute of Health stroke scale at admission was associated with MDR bacteria infection pneumonia (OR [odds ratio] = 1.078, 95%CI [1.017, 1.142]). Long-term tracheotomy (OR = 2.695, 95%CI [1.232, 5.897]), hypoalbuminemia (OR = 473, 95%CI [1.318, 4.642]), and bilateral cerebral hemisphere stroke (OR = 4.021, 95%CI [2.009, 8.048]) were significant clinical risk factors of MDR pneumonia after stroke. The detection rate of MDR bacteria has increased. Understanding the distribution and drug resistance of MDR bacteria in stroke patients with pneumonia in the neurological rehabilitation ward and the related susceptibility of MDR bacteria infection is necessary. This way, the treatment plan can be adjusted more timely, avoiding the abuse of antibiotics.

Benzoic acid derivatives as potent antibiofilm agents against Klebsiella pneumoniae biofilm

Klebsiella pneumoniae is responsible for a significant proportion of human urinary tract infections, and its biofilm is a major virulence. One potential approach to controlling biofilm-associated infections is targeting the adhesin MrkD1P to disrupt biofilm formation. We employed Schrodinger's Maestro tool with the OPLS 2005 force field to dock compounds with the target protein. Two benzoic acid derivatives, 3-hydroxy benzoic acid and 2,5-dihydroxybenzoic acid, had strong binding free energies (-55.57 and -18.68 kcal/mol) and were the most potent compounds. The in-vitro experiments were conducted to validate the in-silico results. The results showed that both compounds effectively inhibited biofilm formation at low concentrations (4 and 8 mg/mL, respectively) and had antibiofilm activity, restricting cell attachment. Both compounds demonstrated a strong biofilm inhibitory effect, with 97% and 89% reduction in biofilm by 3-hydroxy benzoic acid and 2,5-dihydroxybenzoic acid, respectively. These findings suggest that natural compounds can be a potential source of new drugs to combat biofilm-associated infections. The study highlights the potential of targeting adhesin MrkD1P as an effective approach to controlling biofilm-associated infections caused by K. pneumoniae. The results may have implications for the development of new therapies for biofilm-associated infections and pave the way for future research in this area.

Development of an antibody fused with an antimicrobial peptide targeting Pseudomonas aeruginosa: A new approach to prevent and treat bacterial infections

The increase in emerging drug resistant Gram-negative bacterial infections is a global concern. In addition, there is growing recognition that compromising the microbiota through the use of broad-spectrum antibiotics can impact long term patient outcomes. Therefore, there is the need to develop new bactericidal strategies to combat Gram-negative infections that would address these specific issues. In this study, we report and characterize one such approach, an antibody-drug conjugate (ADC) that combines (i) targeting the surface of a specific pathogenic organism through a monoclonal antibody with (ii) the high killing activity of an antimicrobial peptide. We focused on a major pathogenic Gram-negative bacterium associated with antibacterial resistance: Pseudomonas aeruginosa. To target this organism, we designed an ADC by fusing an antimicrobial peptide to the C-terminal end of the VH and/or VL-chain of a monoclonal antibody, VSX, that targets the core of P. aeruginosa lipopolysaccharide. This ADC demonstrates appropriately minimal levels of toxicity against mammalian cells, rapidly kills P. aeruginosa strains, and protects mice from P. aeruginosa lung infection when administered therapeutically. Furthermore, we found that the ADC was synergistic with several classes of antibiotics. This approach described in this study might result in a broadly useful strategy for targeting specific pathogenic microorganisms without further augmenting antibiotic resistance.

Caenorhabditis elegans as an In Vivo Model for the Discovery and Development of Natural Plant-Based Antimicrobial Compounds

Antimicrobial resistance (AMR) due to the prevalence of multidrug-resistant (MDR) pathogens is rapidly increasing worldwide, and the identification of new antimicrobial agents with innovative mechanisms of action is urgently required. Medicinal plants that have been utilised for centuries with minor side effects may hold great promise as sources of effective antimicrobial products. The free-living nematode Caenorhabditis elegans (C. elegans) is an excellent live infection model for the discovery and development of new antimicrobial compounds. However, while C. elegans has widely been utilised to explore the effectiveness and toxicity of synthetic antibiotics, it has not been used to a comparable extent for the analysis of natural products. By screening the PubMed database, we identified articles reporting the use of the C. elegans model for the identification of natural products endowed with antibacterial and antifungal potential, and we critically analysed their results. The studies discussed here provide important information regarding "in vivo" antimicrobial effectiveness and toxicity of natural products, as evaluated prior to testing in conventional vertebrate models, thereby supporting the relevance of C. elegans as a highly proficient model for their identification and functional assessment. However, their critical evaluation also underlines that the characterisation of active phytochemicals and of their chemical structure, and the unravelling of their mechanisms of action represent decisive challenges for future research in this area.

Decolonizing drug-resistant E. coli with phage and probiotics: breaking the frequency-dependent dominance of residents

Widespread antibiotic resistance in commensal bacteria creates a persistent challenge for human health. Resident drug-resistant microbes can prevent clinical interventions, colonize wounds post-surgery, pass resistance traits to pathogens or move to more harmful niches following routine interventions such as catheterization. Accelerating the removal of resistant bacteria or actively decolonizing particular lineages from hosts could therefore have a number of long-term benefits. However, removing resident bacteria via competition with probiotics, for example, poses a number of ecological challenges. Resident microbes are likely to have physiological and numerical advantages and competition based on bacteriocins or other secreted antagonists is expected to give advantages to the dominant partner, via positive frequency dependence. Since a narrow range of Escherichia coli genotypes (primarily those belonging to the clonal group ST131) cause a significant proportion of multidrug-resistant infections, this group presents a promising target for decolonization with bacteriophage, as narrow-host-range viral predation could lead to selective removal of particular genotypes. In this study we tested how a combination of an ST131-specific phage and competition from the well-known probiotic E. coli Nissle strain could displace E. coli ST131 under aerobic and anaerobic growth conditions in vitro. We showed that the addition of phage was able to break the frequency-dependent advantage of a numerically dominant ST131 isolate. Moreover, the addition of competing E. coli Nissle could improve the ability of phage to suppress ST131 by two orders of magnitude. Low-cost phage resistance evolved readily in these experiments and was not inhibited by the presence of a probiotic competitor. Nevertheless, combinations of phage and probiotic produced stable long-term suppression of ST131 over multiple transfers and under both aerobic and anaerobic growth conditions. Combinations of phage and probiotic therefore have real potential for accelerating the removal of drug-resistant commensal targets.

DinB (DNA polymerase IV), ImuBC and RpoS contribute to the generation of ciprofloxacin-resistance mutations in Pseudomonas aeruginosa

We investigated the role(s) of the damage-inducible SOS response dinB and imuBC gene products in the generation of ciprofloxacin-resistance mutations in the important human opportunistic bacterial pathogen, Pseudomonas aeruginosa. We found that the overall numbers of ciprofloxacin resistant (CipR) mutants able to be recovered under conditions of selection were significantly reduced when the bacterial cells concerned carried a defective dinB gene, but could be elevated to levels approaching wild-type when these cells were supplied with the dinB gene on a plasmid vector; in turn, firmly establishing a role for the dinB gene product, error-prone DNA polymerase IV, in the generation of CipR mutations in P. aeruginosa. Further, we report that products of the SOS-regulated imuABC gene cassette of this organism, ImuB and the error-prone ImuC DNA polymerase, are also involved in generating CipR mutations in this organism, since the yields of CipR mutations were substantially decreased in imuB- or imuC-defective cells compared to wild-type. Intriguingly, we found that the mutability of a dinB-defective strain could not be rescued by overexpression of the imuBC genes. And similarly, overexpression of the dinB gene either only modestly or else failed to restore CipR mutations in imuB- or imuC-defective cells, respectively. Combined, these results indicated that the products of the dinB and imuBC genes were acting in the same pathway leading to the generation of CipR mutations in P. aeruginosa. In addition, we provide evidence indicating that the general stress response sigma factor σs, RpoS, is required for mutagenesis in this organism and is in part at least modulating the dinB (DNA polymerase IV)-dependent mutational process. Altogether, these data provide further insight into the complexity and multifaceted control of the mutational mechanism(s) contributing to the generation of ciprofloxacin-resistance mutations in P. aeruginosa.

Graph convolutional network-based fusion model to predict risk of hospital acquired infections

OBJECTIVE

Hospital acquired infections (HAIs) are one of the top 10 leading causes of death within the United States. While current standard of HAI risk prediction utilizes only a narrow set of predefined clinical variables, we propose a graph convolutional neural network (GNN)-based model which incorporates a wide variety of clinical features.

MATERIALS AND METHODS

Our GNN-based model defines patients' similarity based on comprehensive clinical history and demographics and predicts all types of HAI rather than focusing on a single subtype. An HAI model was trained on 38 327 unique hospitalizations while a distinct model for surgical site infection (SSI) prediction was trained on 18 609 hospitalization. Both models were tested internally and externally on a geographically disparate site with varying infection rates.

RESULTS

The proposed approach outperformed all baselines (single-modality models and length-of-stay [LoS]) with achieved area under the receiver operating characteristics of 0.86 [0.84-0.88] and 0.79 [0.75-0.83] (HAI), and 0.79 [0.75-0.83] and 0.76 [0.71-0.76] (SSI) for internal and external testing. Cost-effective analysis shows that the GNN modeling dominated the standard LoS model strategy on the basis of lower mean costs ($1651 vs $1915).

DISCUSSION

The proposed HAI risk prediction model can estimate individualized risk of infection for patient by taking into account not only the patient's clinical features, but also clinical features of similar patients as indicated by edges of the patients' graph.

CONCLUSIONS

The proposed model could allow prevention or earlier detection of HAI, which in turn could decrease hospital LoS and associated mortality, and ultimately reduce the healthcare cost.

How Three Self-Secreted Biofilm Exopolysaccharides of Pseudomonas aeruginosa, Psl, Pel, and Alginate, Can Each Be Exploited for Antibiotic Adjuvant Effects in Cystic Fibrosis Lung Infection

In cystic fibrosis (CF), pulmonary infection with Pseudomonas aeruginosa is a cause of increased morbidity and mortality, especially in patients for whom infection becomes chronic and there is reliance on long-term suppressive therapies. Current antimicrobials, though varied mechanistically and by mode of delivery, are inadequate not only due to their failure to eradicate infection but also because they do not halt the progression of lung function decline over time. One of the reasons for this failure is thought to be the biofilm mode of growth of P. aeruginosa, wherein self-secreted exopolysaccharides (EPSs) provide physical protection against antibiotics and an array of niches with resulting metabolic and phenotypic heterogeneity. The three biofilm-associated EPSs secreted by P. aeruginosa (alginate, Psl, and Pel) are each under investigation and are being exploited in ways that potentiate antibiotics. In this review, we describe the development and structure of P. aeruginosa biofilms before examining each EPS as a potential therapeutic target for combating pulmonary infection with P. aeruginosa in CF, with a particular focus on the current evidence for these emerging therapies and barriers to bringing these therapies into clinic.

The Prevalence of Multidrug-Resistant Enterobacteriaceae among Neonates in Kuwait

Increasing numbers of neonates with serious bacterial infections, due to resistant bacteria, are associated with considerable morbidity and mortality rates. The aim of this study was to evaluate the prevalence of drug-resistant Enterobacteriaceae in the neonatal population and their mothers in Farwaniya Hospital in Kuwait and to determine the basis of resistance. Rectal screening swabs were taken from 242 mothers and 242 neonates in labor rooms and wards. Identification and sensitivity testing were performed using the VITEK^® 2 system. Each isolate flagged with any resistance was subjected to the E-test susceptibility method. The detection of resistance genes was performed by PCR, and the Sanger sequencing method was used to identify mutations. Among 168 samples tested by the E-test method, no MDR Enterobacteriaceae were detected among the neonates, while 12 (13.6%) isolates from the mothers' samples were MDR. ESBL, aminoglycosides, fluoroquinolones, and folate pathway inhibitor resistance genes were detected, while beta-lactam-beta-lactamase inhibitor combinations, carbapenems, and tigecycline resistance genes were not. Our results showed that the prevalence of antibiotic resistance in Enterobacteriaceae obtained from neonates in Kuwait is low, and this is encouraging. Furthermore, it is possible to conclude that neonates are acquiring resistance mostly from the environment and after birth but not from their mothers.

Rapid Escherichia coli Cloned DNA Detection in Serum Using an Electrical Double Layer-Gated Field-Effect Transistor-Based DNA Sensor

In this study, a rapid diagnosis platform was developed for the detection of Escherichia coli O157:H7. An electrical double layer (EDL)-gated field-effect transistor-based biosensor (BioFET) as a point-of-care testing device is demonstrated with its high sensitivity, portability, high selectivity, quick response, and ease of use. The specially designed ssDNA probe was immobilized on the extended gate electrode to bind the target complementary DNA segment of E. coli, resulting in a sharp drain current change within minutes. The limit of detection for target DNA is validated to a concentration of 1 fM in buffer solution and serum. Meanwhile, the results of a Kelvin probe force microscope were shown to have reduced surface potential of the DNA immobilized sensors before and after the cDNA detection, which is consistent with the decreased drain current of the BioFET. A 1.2 kb E. coli duplex DNA synthesized in plasmid was sonicated and detected in serum samples with the sensor array. Gel electrophoresis was used to confirm the efficiency of sonication by elucidating the length of DNA. Those results show that the EDL-gated BioFET system is a promising platform for rapid identification of pathogens for future clinical needs.

Bioinspired nanoflakes with antifouling and mechano-bactericidal capacity

Pathogenic bacteria contamination ubiquitously occurs on high-contact surfaces in hospitals and has long been a threat to public health, inducing severe nosocomial infections that cause multiple organ dysfunction and increased hospital mortality. Recently, nanostructured surfaces with mechano-bactericidal properties have shown potential for modifying material surfaces to fight against the spread of pathogenic microorganisms without the risk of triggering antibacterial resistance. Nevertheless, these surfaces are readily contaminated by bacterial attachment or inanimate pollutants like solid dust or common fluids, which has greatly weakened their antibacterial capabilities. In this work, we discovered that the nonwetting Amorpha fruticosa leaf surfaces are equipped with mechano-bactericidal capacity by means of their randomly-arranged nanoflakes. Inspired by this discovery, we reported an artificial superhydrophobic surface with similar nanofeatures and superior antibacterial abilities. Compared to conventional bactericidal surfaces, this bioinspired antibacterial surface was synergistically accompanied by antifouling performances, which significantly prevent either initial bacterial attachment or inanimate pollutants like dust covering and fluid contaminants. Overall, the bioinspired antifouling nanoflakes surface holds promise as the design of next-generation high-touch surface modification that effectively reduces the transmission of nosocomial infections.

Polymyxin combination therapy for multidrug-resistant, extensively-drug resistant, and difficult-to-treat drug-resistant gram-negative infections: is it superior to polymyxin monotherapy?

INTRODUCTION

The increasing prevalence of infections with multidrug-resistant (MDR), extensively-drug resistant (XDR) or difficult-to-treat drug resistant (DTR) Gram-negative bacilli (GNB), including Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae, Enterobacter species, and Escherichia coli poses a severe challenge.

AREAS COVERED

The rapid growing of multi-resistant GNB as well as the considerable deceleration in development of new anti-infective agents have made polymyxins (e.g. polymyxin B and colistin) a mainstay in clinical practices as either monotherapy or combination therapy. However, whether the polymyxin-based combinations lead to better outcomes remains unknown. This review mainly focuses on the effect of polymyxin combination therapy versus monotherapy on treating GNB-related infections. We also provide several factors in designing studies and their impact on optimizing polymyxin combinations.

EXPERT OPINION

An abundance of recent in vitro and preclinical in vivo data suggest clinical benefit for polymyxin-drug combination therapies, especially colistin plus meropenem and colistin plus rifampicin, with synergistic killing against MDR, XDR, and DTR P. aeruginosa, K. pneumoniae and A. baumannii. The beneficial effects of polymyxin-drug combinations (e.g. colistin or polymyxin B + carbapenem against carbapenem-resistant K. pneumoniae and carbapenem-resistant A. baumannii, polymyxin B + carbapenem + rifampin against carbapenem-resistant K. pneumoniae, and colistin + ceftolozan/tazobactam + rifampin against PDR-P. aeruginosa) have often been shown in clinical setting by retrospective studies. However, high-certainty evidence from large randomized controlled trials is necessary. These clinical trials should incorporate careful attention to patient's sample size, characteristics of patient's groups, PK/PD relationships and dosing, rapid detection of resistance, MIC determinations, and therapeutic drug monitoring.

Anti-Pseudomonas aeruginosa Vaccines and Therapies: An Assessment of Clinical Trials

Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen that causes high morbidity and mortality in cystic fibrosis (CF) and immunocompromised patients, including patients with ventilator-associated pneumonia (VAP), severely burned patients, and patients with surgical wounds. Due to the intrinsic and extrinsic antibiotic resistance mechanisms, the ability to produce several cell-associated and extracellular virulence factors, and the capacity to adapt to several environmental conditions, eradicating P. aeruginosa within infected patients is difficult. Pseudomonas aeruginosa is one of the six multi-drug-resistant pathogens (ESKAPE) considered by the World Health Organization (WHO) as an entire group for which the development of novel antibiotics is urgently needed. In the United States (US) and within the last several years, P. aeruginosa caused 27% of deaths and approximately USD 767 million annually in health-care costs. Several P. aeruginosa therapies, including new antimicrobial agents, derivatives of existing antibiotics, novel antimicrobial agents such as bacteriophages and their chelators, potential vaccines targeting specific virulence factors, and immunotherapies have been developed. Within the last 2-3 decades, the efficacy of these different treatments was tested in clinical and preclinical trials. Despite these trials, no P. aeruginosa treatment is currently approved or available. In this review, we examined several of these clinicals, specifically those designed to combat P. aeruginosa infections in CF patients, patients with P. aeruginosa VAP, and P. aeruginosa-infected burn patients.

Worldwide Dissemination of blaKPC Gene by Novel Mobilization Platforms in Pseudomonas aeruginosa: A Systematic Review

The dissemination of blaKPC-harboring Pseudomonas aeruginosa (KPC-Pa) is considered a serious public health problem. This study provides an overview of the epidemiology of these isolates to try to elucidate novel mobilization platforms that could contribute to their worldwide spread. A systematic review in PubMed and EMBASE was performed to find articles published up to June 2022. In addition, a search algorithm using NCBI databases was developed to identify sequences that contain possible mobilization platforms. After that, the sequences were filtered and pair-aligned to describe the blaKPC genetic environment. We found 691 KPC-Pa isolates belonging to 41 different sequence types and recovered from 14 countries. Although the blaKPC gene is still mobilized by the transposon Tn4401, the non-Tn4401 elements (NTEKPC) were the most frequent. Our analysis allowed us to identify 25 different NTEKPC, mainly belonging to the NTEKPC-I, and a new type (proposed as IVa) was also observed. This is the first systematic review that consolidates information about the behavior of the blaKPC acquisition in P. aeruginosa and the genetic platforms implied in its successful worldwide spread. Our results show high NTEKPC prevalence in P. aeruginosa and an accelerated dynamic of unrelated clones. All information collected in this review was used to build an interactive online map.

Extended-spectrum beta-lactamase-producing Enterobacteriaceae related urinary tract infection in adult cancer patients: a multicenter retrospective study, 2015-2019

BACKGROUND

The aim of this study was to investigate the prevalence and risk factors of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae related urinary tract infections (UTI) in adult cancer patients.

METHODS

We conducted a retrospective study of three cancer hospitals centered on Cancer Hospital of Chinese Academy of Medical Sciences from 2015 to 2019. The clinical characters, risk factors and antimicrobial susceptibility of ESBL-producing Enterobacteriaceae UTI in adult cancer patients were described and analyzed.

RESULTS

A total of 4967 specimens of UTI were evaluated, of which 909 were positive. After excluding multiple infection bacteria, non-conforming strains, inconsistent pathological information, no drug sensitivity test or medical records, 358 episodes remained. Among them, 160 episodes belonged to ESBL-producing Enterobacteriaceae, while 198 were classified into non-ESBL group. The prevalence of ESBL UTI circled around 39.73 to 53.03% for 5 years. Subgroup analysis by tumor type revealed that 62.5% of isolates from patients with urological tumors were ESBL positive. Multivariate analysis showed that tumor metastasis (OR 3.41, 95%CI 1.84-6.30), urological cancer (OR 2.96, 95%CI 1.34-6.53), indwelling catheter (OR 2.08, 95%CI 1.22-3.55) and surgery or invasive manipulation (OR 1.98, 95%CI 1.13-3.50) were the independent risk factors. According to antimicrobial sensitivity, meropenem, imipenem and piperacillin/tazobactam were the most commonly used antibiotics for ESBL-producing Enterobacteriaceae UTI.

CONCLUSIONS

In view of the high prevalence, clinicians should be alert to the occurrence of ESBL UTI, especially for patients with urological cancer or metastatic tumors. Regular replacement of urinary catheters, reduction of unnecessary invasive operations and selection of appropriate antibiotics are the necessary conditions to deal with the occurrence of ESBL UTI in adult cancer patients.

Puerarin@Chitosan composite for infected bone repair through mimicking the bio-functions of antimicrobial peptides

It is important to eliminate lipopolysaccharide (LPS) along with killing bacteria in periprosthetic joint infection (PJI) therapy for promoting bone repair due to its effect to regulate macrophages response. Although natural antimicrobial peptides (AMPs) offer a good solution, the unknown toxicity, high cost and exogenetic immune response hamper their applications in clinic. In this work, we fabricated a nanowire-like composite material, named P@C, by combining chitosan and puerarin via solid-phase reaction, which can finely mimic the bio-functions of AMPs. Chitosan, serving as the bacteria membrane puncture agent, and puerarin, serving as the LPS target agent, synergistically destroy the bacterial membrane structure and inhibit its recovery, thus endowing P@C with good antibacterial property. In addition, P@C possesses good osteoimmunomodulation due to its ability of LPS elimination and macrophage differentiation modulation. The in vivo results show that P@C can inhibit the LPS induced bone destruction in the Escherichia coli infected rat. P@C exhibits superior bone regeneration in Escherichia coli infected rat due to the comprehensive functions of its superior antibacterial property, and its ability of LPS elimination and immunomodulation. P@C can well mimic the functions of AMPs, which provides a novel and effective method for treating the PJI in clinic.

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P@C was fabricated through solid reaction with chitosan and puerarin.

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P@C punctures bacteria membrane and eliminates LPS, thus sterilizes bacteria.

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P@C improves bone formation of PEEK under infection via polarizing macrophage to M2.