Global mortality associated with 33 bacterial pathogens in 2019: a systematic analysis for the Global Burden of Disease Study 2019

Rapid and accurate testing for urinary tract infection: new clothes for the emperor

SUMMARYUrinary tract infection (UTI) is among the most common infections in clinical practice. In some cases, if left untreated, it can lead to pyelonephritis and urosepsis. In other cases, UTI resolves without treatment. Clinical diagnosis is typically based on patient symptoms and/or urinalysis, including urine dipsticks. The standard urine culture method is sometimes employed to identify the suspected urinary pathogen (uropathogen) and/or guide antimicrobial choice, but results are rarely available before 24 h. The standard urine culture method also misses fastidious, anaerobic, and slow-growing uropathogens and rarely reports polymicrobial infections. The unexplained combination of negative urine cultures with persistent urinary tract symptoms is distressing to both patients and clinicians. Given the broad appreciation of the advantages provided by rapid testing (e.g., for COVID-19 or influenza A), a rapid, accurate diagnostic test is needed to deliver timely treatment to patients seeking care for UTI that optimizes antibiotic stewardship. Herein, we discuss progress being made toward an accessible, timely (i.e., within hours), accurate assay with results that are clinically useful for the treating clinician within the timeframe of the infection (i.e., the growth rate of the pathogen(s)). New and emerging uropathogens often overlooked by current diagnostic techniques are also reviewed.

Determining Molecular-Level Interactions of Carboxyl-Functionalized Nanodiamonds with Bacterial Membrane Models as the Basis for Antimicrobial Activity

Carbon-based nanostructures, such as carboxylated nanodiamonds (NDCOOHs), are promising to combat resistant bacterial strains by targeting their protective membranes. Understanding their interactions with bacterial membranes is therefore important for elucidating the mechanisms underlying NDCOOHs antimicrobial activity. In this study, we investigated the incorporation of NDCOOHs into lipid Langmuir monolayers mimicking cytoplasmic membranes of Escherichia coli and Staphylococcus aureus, model systems for Gram-negative and Gram-positive bacteria, respectively. Using polarization-modulated infrared reflection-absorption spectroscopy (PM-IRRAS), we observed significant interactions between NDCOOHs and the polar head groups of the E. coli lipid monolayer, driven by electrostatic attraction to ammonium groups and repulsion from phosphate and carbonyl ester groups, limiting deeper penetration into the lipid chains. In contrast, S. aureus monolayers exhibited more pronounced changes in their hydrocarbon chains, indicating deeper NDCOOHs penetration. NDCOOHs incorporation increased the surface area of the E. coli monolayer by approximately 4% and reduced that of S. aureus by about 8%, changes likely attributed to lipid oxidation induced by superoxide and/or hydroxyl radicals generated by NDCOOHs. These findings highlight the distinct interactions of NDCOOHs with Gram-positive and Gram-negative lipid membranes, offering valuable insights for their development as targeted antimicrobial agents.

A steam-mediated isothermal amplification and flocculation-based detection platform for electricity-free point of care diagnostics

Approximately 9% of the global population lacks access to reliable electricity, and the absence of affordable, electricity-free diagnostic tools hinders early detection of infectious diseases, exacerbating public health burdens in resource-limited settings. We introduce SteamFloc-LAMP - an electricity-free molecular diagnostic platform engineered for instrument-free detection of pathogenic nucleic acid targets. The platform leverages steam-mediated heating from boiling water to sustain the isothermal conditions required for Loop-Mediated Isothermal Amplification (LAMP). Thermal characterization of the steam-mediated heating system identified parameters that enable the consistent maintenance of optimal temperatures for LAMP reactions with minimal fluctuations. Visual end-point detection was achieved through a bridging flocculation mechanism, which exploits the interaction between LAMP amplicons, spermine, and charcoal particles, leading to visible aggregation in positive samples, thus enabling naked-eye detection without the need for specialized equipment or expensive reagents like fluorophores or colorimetric dyes. The SteamFloc-LAMP assay targeted the lipL32 gene, recognized for its exclusivity to pathogenic Leptospira strains. The assay achieved a detection limit of 100 fg of genomic DNA per reaction (∼90 genome copies). Specificity tests using lipL32-specific primers demonstrated the assay's ability to distinguish pathogenic Leptospira accurately, with no cross-reactivity with ligB, ligA, or lipL41 genes found in nonpathogenic strains. A blind test involving DNA extracted from Leptospira reference cultures further validated the assay's diagnostic accuracy, aligning with PCR results. These findings demonstrate the SteamFloc-LAMP assay as a reliable, simple, and cost-effective field deployable diagnostic tool with significant implications for point-of-care detection.

Antimicrobial Stewardship Impact on Antibiotic Use in Three Tertiary Hospitals in Zambia: A Comparative Point Prevalence Survey

Introduction: Antimicrobial stewardship (AMS) can improve the rational use of antibiotics in hospitals. This study assessed the impact of a multifaceted AMS intervention on antibiotic use and prescribing patterns at three tertiary hospitals in Zambia. Methods: Point Prevalence Surveys (PPS) were conducted in three tertiary hospitals in August 2022 and in October 2023. It was part of a 3-year AMS demonstration project that aimed to optimize the use of antibiotics in treating urinary tract infections (UTIs) and bloodstream infections (BSIs) in various health sector settings in Zambia. Up to 170 medical records in 2022 and 265 in 2023 were included in the assessment. Results: Overall, the prevalence of antibiotic use in this PPS was 75%. Eighty-one percent (81%) and 71% of patients assessed were on at least one antibiotic in 2022 and 2023, respectively, indicating a decrease of 10%. Similarly, prescribing ceftriaxone, the most prescribed antibiotic, declined from an average of 48% in 2022 to 38% in 2023. Adherence to Standard Treatment Guidelines (STGs) slightly increased from 42% in 2022 to 45% in 2023. Additionally, antibiotic prescribing was reduced from 1.38 to 1.21. Conclusions: Antimicrobial stewardship had an early positive impact on antibiotic use and adherence to Standard Treatment Guidelines.

γ Irradiation Alters the Staphylococcus aureus Proteome and Enhances Pathogenicity

Staphylococcus aureus (S. aureus) infection has become one of the most common and severe complications among cancer patients. The impact of γ radiation from radiotherapy on S. aureus's growth and virulence is not yet fully understood. In this study, S. aureus was exposed to γ radiation at a dose of 100 Gy, and its descendants were cultured under normal conditions. Proteome alternations of unirradiated, irradiated, and descendants of irradiated S. aureus were identified by using data-independent acquisition (DIA) proteomic technology. To investigate the consequences of proteome alternations induced by γ irradiation in S. aureus, functional enrichment analysis, pathway enrichment analysis, and protein-protein interaction network analysis were performed. Differentially expressed proteins (DEPs) in the irradiated S. aureus and its descendants were primarily enriched in lipoteichoic acid biosynthesis, S. aureus infection, two-component system, and cationic antimicrobial peptide resistance, suggesting an enhanced infection ability. A strong infection ability is typically associated with increased biofilm formation. Both the proteome study and the biofilm assay indicate that γ irradiation enhances the infection ability of S. aureus, likely resulting in increased pathogenicity.

Infection characteristics among Serratia marcescens capsule lineages

Serratia marcescens is a healthcare-associated pathogen that can cause severe infections including bacteremia and pneumonia. The capsule polysaccharide of S. marcescens is a bacteremia fitness determinant and previous work defined capsule locus (KL) diversity within the species. Strains belonging to KL1 and KL2 capsule clades produce sialylated polysaccharides and represent the largest subpopulation of isolates from clinical origin. In this study, the contribution of these and other S. marcescens capsules to infection was determined in animal and cellular models. Using a murine model of primary bacteremia, clinical isolates of multiple KL types demonstrated capsule-dependent colonization of spleen, liver, and kidney following tail vein inoculation. Similar results were observed using a bacteremic pneumonia model, in that all tested strains of clinical origin demonstrated a requirement for capsule in both the primary lung infection site and for bloodstream dissemination to secondary organs. Finally, capsule from each KL clade was examined for the ability to resist internalization by bone marrow-derived macrophages. Only the sialylated KL1 and KL2 clade strains exhibited capsule-dependent inhibition of internalization, including KL2 capsule produced in a heterologous background. Together these findings indicate that lineage-specific resistance to macrophage phagocytosis may enhance survival and antibacterial defenses of clinically-adapted S. marcescens.

Ultradense Electrochemical Chips with Arrays of Nanostructured Microelectrodes to Enable Sensitive Diffusion-Limited Bioassays

Nanostructured microelectrodes (NMEs) are an attractive alternative to yield sensitive bioassays in unprocessed samples. However, although valuable for different applications, nanoporous NMEs usually cannot boost the sensitivity of diffusion-limited analyses because of the enlarged Debye length within the nanopores, which reduces their accessibility. To circumvent this limitation, nanopore-free gold NMEs were electrodeposited from 45 μm SU-8 apertures, featuring nanoridged microspikes on a recessed surface of gold thin film while carrying interconnected crown-like and spiky structures along the edge of a SU-8 passivation layer. These structures were grown onto ultradense, vertical array chips that offer a promising strategy for translating reproducible, high-resolution, and cost-effective sensors into real-world applications. The NMEs yielded reproducible analyses, while machine learning allowed us to predict the analytical responses from NME electrodeposition data. By taking advantage of the high surface area and accessible structure of the NMEs, these structures provided a sensitivity for [Fe(CN)6]3-/4- that was 5.5× higher than that of bare WEs while also delivering a moderate antibiofouling property in undiluted human plasma. As a proof of concept, these electrodes were applied toward the fast (22 min) and simple determination of Staphylococcus aureus by monitoring the oxidation of [Fe(CN)6]4-, which acted as a cellular respiration rate redox reporter. The sensors also showed a wide dynamic range, spanning 5 orders of magnitude, and a calculated limit of detection of 0.2 CFU mL-1.

Formulation and evaluation of therapeutic antimicrobial citrus and Manuka honey creams with aloe vera, mint essential oil, and Indian costus

Honey has long been recognized for its antimicrobial properties, attributed to components such as polyphenols and biodefense proteins. Among honey types, Manuka honey, rich in methylglyoxal, and citrus honey, abundant in flavonoids and bioactive enzymes, exhibit potent antimicrobial activity. This study aims to enhance the antimicrobial and antibiofilm efficacy of Manuka and citrus honey by incorporating natural additives-aloe vera, Indian costus, and mint essential oil-into cream formulations. Two emulsion types, aerosil fumed silica-based and arabic gum-based, were prepared and optimized using sonication. The antimicrobial activity of these formulations was assessed against pathogenic bacteria, including Bacillus cereus, Pseudomonas aeruginosa, Salmonella enterica subsp. enterica serovar Typhimurium, Methicillin-resistant Staphylococcus aureus, Listeria monocytogenes, Micrococcus luteus, Escherichia coli O157:H7, and Klebsiella pneumoniae, as well as fungi such as Candida albicans and Aspergillus niger. The most effective formulations demonstrated inhibition zones of up to 28 mm against B. cereus and 24 mm against S. Typhimurium. Additionally, antibiofilm activity was evaluated using a 3D biofilm model, with formulations containing citrus honey and Indian costus or Manuka honey and aloe vera achieving biofilm reductions of 44.39% and 21.33%, respectively, against P. aeruginosa and MRSA. Furthermore, the composition of the citrus honey was analyzed using gas chromatography-mass spectrometry to identify the volatile and non-volatile compounds contributing to their antimicrobial properties. These findings suggest that honey-based formulations enhanced with natural additives hold significant potential for combating biofilm-associated infections.

Temperate bacteriophage SapYZUs7 alters Staphylococcus aureus fitness balance by regulating expression of phage resistance, virulence and antimicrobial resistance gene

Temperate bacteriophages are crucial for maintaining the pathogenicity and fitness of S. aureus, which also show promise as a biocontrol agent for S. aureus. However, the fitness benefit and cost of lysogeny by S. aureus temperate phages and their underlying mechanisms remain unexplored. In this study, phage resistance, virulence, antimicrobial resistance (AMR), transcriptome, and metabolome of phage SapYZUs7 lysogenic and non-lysogenic S. aureus strains were compared. Whole-genome analysis revealed that SapYZUs7 harbouring smaII associated with a single-protein MazF-like antiphage system could be integrated into the genome of S. aureus isolates. Notably, lysogenic S. aureus exhibited higher phage resistance, a lower growth rate, and inhibited metabolic activity compared to the parental strains, indicating interference of phage reproduction by smaII. Moreover, prophages carrying smaII are widely distributed across S. aureus and harboured other virulence factor (VF) and AMR genes. Besides, the SapYZUs7-integration increased phagocytosis resistance but decreased adhesion, biofilm formation, and AMR. The combined use of SapYZUs7 and antibiotics exhibited a better bactericidal effect than SapYZUs7 or the antibiotics alone. Consistently, integrated omics analysis suggested that SapYZUs7-lysogeny downregulated multiple VF and AMR genes. Our analysis suggests that SmaII drives mutualistic phage-host interactions through lysogenic conversion. The fitness cost of SapYZUs7-integration is the downregulated expression of VF and AMR genes, serving as an alternative candidate as a biocontrol agent for methicillin-resistant S. aureus and multidrug-resistant S. aureus.

A genomic and phenotypic investigation of pigeon-adaptive Salmonella

Salmonella, a significant threat to public safety, inflicts substantial economic losses on the poultry industry. The unique "parental feeding" breeding model of pigeon farms, against the "all-in & all-out" biosecurity strategy, makes them susceptible to Salmonella infections and subsequent outbreaks of pigeon paratyphoid. This study initially studied three pigeon paratyphoid outbreak incidents in Henan, China, in which 53 strains of pigeon-origin Salmonella Typhimurium (STM) were identified. Whole-genome sequencing (WGS) and antimicrobial-resistant profile analysis revealed that the three outbreaks were caused by distinct STM clones (ST128-DT2, ST19-DT99). Global phylogenetic analysis suggested that the United States is a possible origin, indicating a risk of intercontinental transmission via pigeon eggs. Further bacterial virulence and invasion assays, including in vitro and in vivo assays, revealed that pigeon-host-adaptive STM, compared to broad-host-range STM, carried fewer resistance genes, exhibited higher invasion indices and pseudogene levels, displayed a non-rdar (red dry and rough) phenotype, and had strong biofilm formation capability. Additionally, they showed reduced virulence and invasiveness in mice but a pigeon-adaptive feature in cogent models. The collective results support the host adaptation for pigeons among DT2 and DT99 phage-type isolates.

Utilising routinely collected clinical data through time series deep learning to improve identification of bacterial bloodstream infections: a retrospective cohort study

BACKGROUND

Blood cultures are the gold standard for diagnosing bacterial bloodstream infections, but test results are only available 24-48 h after sampling. We aimed to develop and evaluate models using health-care data to predict bloodstream infections in patients admitted to hospital.

METHODS

In this retrospective cohort study, we used routinely collected blood biomarkers and demographic data from patients who underwent blood sample collection for testing via culture between March 3, 2014, and Dec 1, 2021, at Imperial College Healthcare NHS Trust (London, UK) as model features. Data up to 14 days before blood sample collection were provided to long short-term memory (LSTM) or static logistic regression models. The primary outcome was prediction of blood culture results, defined as a pathogenic bloodstream infection (ie, isolation of pathogenic bacteria of interest) or no bloodstream infection (ie, no growth or contamination). Data collected up to Feb 28, 2021 (n=15 212) comprised the training set and were evaluated against a temporal hold-out test set comprising patients who were sampled after March 1, 2021 (n=5638).

FINDINGS

Among 20 850 patients with available data, pathogenic bacteria were observed in the cultured blood samples of 3866 (18·5%) patients. 2920 (62·2%) of 4897 patients who had their blood samples taken more than 48 h after admission to hospital had pathogenic bloodstream infections, and so were defined as having hospital-acquired bloodstream infections. Including data from the 7 days before admission (7-day window approach) and using five-fold cross validation in the training set gave an area under receiver operator curve (AUROC) of 0·75 (IQR 0·68-0·82) and an area under the precision recall curve (AUPRC) of 0·58 (0·46-0·77) for static models and an AUROC of 0·92 (0·91-0·93) and AUPRC of 0·75 (0·72-0·76) for the LSTM model. In the hold-out test set performances were: AUROC of 0·74 (95% CI 0·70-0·78) and AUPRC of 0·48 (0·43-0·53) for static models and AUROC of 0·97 (0·96-0·97) and AUPRC of 0·65 (0·60-0·70) for LSTM. Removal of time series information resulted in lower model performance, particularly for hospital-acquired bloodstream infections. Dynamics of C-reactive protein concentration, eosinophil count, and platelet count were important features for prediction of blood culture results.

INTERPRETATION

Deep learning models accounting for longitudinal changes could support individualised clinical decision making for patients at risk of bloodstream infections. Appropriate implementation into existing diagnostic pathways could enhance diagnostic stewardship and reduce unnecessary antimicrobial prescribing.

FUNDING

UK Department of Health and Social Care, the National Institute for Health and Care Research, and the Wellcome Trust.

Nasopharyngeal carriage of Staphylococcus aureus in a rural population, Sierra Leone

BACKGROUND

Nasopharyngeal colonization with Staphylococcus aureus is a risk factor for subsequent infection. Isolates from colonization can therefore provide important information on virulence factors and antimicrobial resistance when data from clinical isolates are lacking. The aim of this study was to assess colonization rates, resistance patterns and selected virulence factors of S. aureus from rural Sierra Leone.

METHODS

Residents of randomly selected houses in Masanga, Sierra Leone were included in a cross-sectional study (8-11/2023). Participants were tested for nasopharyngeal S. aureus colonization using selective culture media. Risk factors for colonization were documented in a standardized questionnaire. Isolates were genotyped and tested for antimicrobial susceptibility and selected virulence factors (e.g. Panton-Valentine leukocidin, capsular types).

RESULTS

Of 300 participants (62.7 % females, median age: 16 years), 168 (56 %) were colonized with S. aureus-related complex; six participants carried two different S. aureus genotypes, resulting in a total number of 174 isolates. Resistance to penicillin was predominant (97.1 %, 169/174), followed by tetracycline (66.1 %, 115/174), co-trimoxazole (56.9 %, 99/174) and oxacillin (24.1 %, 42/174, all mecA-positive, mostly associated with ST8/PVL-negative). PVL gene was detected in 21.3 % of isolates (37/174) mainly associated with ST15 and ST152. Except for past use of antimicrobials (p = 0.019), no specific risk factors such as comorbidities including hemoglobin variants were associated with S. aureus nasopharyngeal colonization.

CONCLUSION

The prevalence of methicillin-resistant and PVL-positive methicillin-susceptible S. aureus (MRSA/MSSA) is high in a rural community of asymptomatic carriers in Sierra Leone. Measures to contain the spread of MRSA, also in the community, are needed.

World Health Organization priority antimicrobial resistance in Enterobacterales, Acinetobacter baumannii, Pseudomonas aeruginosa, Staphylococcus aureus and Enterococcus faecium healthcare-associated bloodstream infections in Brazil (ASCENSION): a prospective, multicentre, observational study

Background

Carbapenem-resistant Enterobacterales (CRE), Acinetobacter baumannii (CRAB), Pseudomonas aeruginosa (CRPA), methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VRE) are listed by World Health Organization (WHO) as priority antimicrobial-resistant bacteria. Data on WHO Priority Antimicrobial resistance Phenotype (WPAP) bacteria from low- and middle-income countries are scarce. In this study, we investigated the occurrence of WPAP in healthcare-associated bloodstream infections (BSI) in Brazil, an upper-middle-income country in South America.

Methods

ASCENSION was a prospective, multicentre, observational study conducted in 14 hospitals from four of five Brazilian regions. Enterobacterales, A. baumannii, P. aeruginosa, S. aureus and E. faecium BSIs in hospitalised patients were analysed. The primary outcome was the frequency of WPAP among all bacteria of interest. Secondary outcomes were incidence-density of bacteria isolates in hospitalised patients, WPAP proportions within bacterial species, and 28-day mortality. PCR for carbapenemase genes was performed in carbapenem-resistant Gram-negative bacteria.

Findings

Between August 15, 2022, and August 14, 2023, 1350 isolates (1220 BSI episodes) were included. WPAP accounted for 38.8% (n = 524; 95% Confidence Interval 32.0-46.1) of all isolates, with CRE (19.3%) as the most frequent, followed by CRAB (9.6%), MRSA (4.9%), VRE (2.7%), and CRPA (2.4%). Incidence-density of all and WPAP isolates were 1.91 and 0.77/1000 patients-day, respectively. Carbapenem-resistant Klebsiella pneumoniae (CRKP) was the most common CRE, corresponding to 14.2% of all BSIs. A. baumannii isolates presented the highest proportion of WPAP (87.8%). Mortality rates were higher in patients with BSIs by WPAP than non-WPAP isolates. KPC (64.4%) was the predominant carbapenemase in CRE, followed by NDM (28.4%) and KPC + NDM co-production (7.1%). OXA-23 was the most frequent in CRAB.

Interpretation

A high frequency of WPAP bacteria, particularly CRKP and CRAB, were found in healthcare-associated BSIs in Brazil, posing them as a major public health problem in this country.

Funding

National Council for Scientific and Technological Development, Brazil.

Economic and Disease Burden Associated with Invasive Escherichia coli Disease in the United States

INTRODUCTION

Invasive Escherichia coli disease (IED) incidence has increased over recent years among aging populations and has rising antimicrobial resistance. Here, we report on a comparative, cross-sectional, retrospective analysis of US patients with IED to quantify IED-related healthcare resource utilization (HCRU), costs, and impact on health-related quality of life (HRQoL).

METHODS

This study included Kaiser Permanente Northwest (KPNW) members aged ≥ 60 years enrolled between July 2019 and January 2020. Patients were divided into three groups: Group 1 had experienced a recent IED episode (≤ 3 weeks before enrollment); Group 2 had experienced a former IED episode (13-18 months before enrollment); Group 3 was at risk with no prior history of IED. Data were collected from electronic hospital records, a patient survey, and the EuroQol 5-Dimension 5-Level (EQ-5D-5L) questionnaire. Mean costs were adjusted according to individual follow-up.

RESULTS

Patient characteristics were generally consistent across Groups 1 (n = 289), 2 (n = 319), and 3 (n = 340). Inpatient hospitalization was observed in 84%, 44%, and 15% of patients in Groups 1, 2 and 3, respectively. Mean direct costs per patient (per 30-day follow-up) were $17,168, $2530, and $1094 in Groups 1, 2, and 3, respectively. Mean total costs per patient in the year following an IED episode (Group 2) were $35,034 vs. $16,163 in the at-risk Group 3. HRQoL was poor for patients with recent IED, with a mean EQ-5D-5L utility index value of 0.25 on the worst day of illness. During a 12-month follow-up period, rehospitalization rates and mean number of antibiotic prescriptions were ~ threefold higher for patients who recovered from IED vs. those at risk.

CONCLUSIONS

These data demonstrate substantial short- and long-term impacts of IED on HCRU, IED-related costs, and HRQoL. Additional research is needed to further value the impact of novel IED prevention strategies.

Spectroscopic analysis of bacterial photoreactivation

With the rise of bacterial infections and antibiotic resistance, spectroscopic devices originally developed for bacterial detection have shown promise to rapidly identify bacterial strains and determine the ratio of live to dead bacteria. However, the detection of the photoreactivated pathogens remains a critical concern. This study utilizes fluorescence and Raman spectroscopy to analyze bacterial responses to UV irradiation and subsequent photoreactivation. Our experimental results reveal limitations in fluorescence spectroscopy for detecting photoreactivated bacteria, as the intense fluorescence of tryptophan and tyrosine amino acids masks the fluorescence emitted by thymine molecules. Conversely, Raman spectroscopy proves more effective, showing a detectable decrease in band intensities of E. coli bacteria at 1248 and 1665 cm-1 after exposure to UVC radiation. Subsequent UVA irradiation results in the partial restoration of these band intensities, indicating DNA repair and bacterial photoreactivation. This enhanced understanding aims to improve the accuracy and effectiveness of these spectroscopic tools in clinical and environmental settings.

Antimicrobial Potential of a Formazanate-Based Mercury(II) Complex: In Vitro- and In Silico-Based Insights

Herein, we present a distorted square pyramidal mercury complex, [HgII(L)Cl] (1), based on a quinoline-substituted formazan ligand LH[3-Cyano-1,5-(quinolin-8-yl)formazan], which was evaluated for its anti-bacterial activity in vitro. Complex 1 was prepared by refluxing 3-Cyano-1,5-(quinolin-8-yl)formazan ligand and mercury chloride(II) in equimolar quantity and was characterized utilizing a range of analytical methods, including single crystal X-ray diffraction (SCXRD) technique. The crystal packing in complex 1 has been elucidated using supramolecular investigations, which have shown the presence of fascinating Hg-Cl⋅⋅⋅Hg intermolecular spodium bonds of the order 3.348 Å. The antimicrobial activity of the formazanate-based mercury(II) complex (1) was assessed against Gram-positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacterial pathogens. In addition, the plausible therapeutic target of the formazanate-based mercury(II) complex was determined through in silico pharmacophore-guided rational drug designing approach. Based on the in silico results, a conceivable molecular mechanism of the observed bactericidal action of the newly synthesized [HgII(L)Cl] complex (1) has also been suggested.

Characterization of carbapenem-resistant Klebsiella pneumoniae from blood cultures in Gaza Strip hospitals, Palestine

BACKGROUND

Carbapenem-resistant Klebsiella pneumoniae (CRKP) is a difficult to treat organism owing to limited therapeutic options. So far, little is known about the molecular characteristics of CRKP in Palestine.

OBJECTIVES

The aim of this study was to investigate the antimicrobial resistance patterns, multilocus sequence types (ST) and resistance genes among clinical K. pneumoniae isolates from hospitalized patients in Gaza Strip, Palestine.

METHODS

K. pneumoniae from blood cultures (n = 55) were collected at two hospitals in Gaza Strip (2023) and identified by MALDI-TOF-MS. Antimicrobial susceptibility testing was done using VITEK-2 automated systems. Carbapenemases were phenotypically detected. Whole genome sequencing (WGS) of all CRKP isolates was performed to assess determinants for carbapenem resistance and genotypes.

RESULTS

Of all K. pneumoniae isolates, 40 % (n = 22/55) were CRKP. Among CRKP, cefiderocol showed the least resistance (46 %, n = 10/22) while ceftazidime/avibactam showed a synergistic effect with aztreonam (36 %, n = 8/22). The majority (86 %, n = 19/22) of CRKP carried metallo-β-lactamases, and only 9 % (n = 2/22) encoded OXA-48 carbapenemase. WGS of CRKP revealed that the predominant genotype is multilocus sequence type ST147 harboring blaNDM-5 and blaCTX-M-15.

CONCLUSION

The proportion of CRKP among all K. pneumoniae from bloodstream infection in Gaza Strip is high (40 %) and mainly associated with the blaNDM-5-positive high-risk clone ST147.

The monogenic landscape of human infectious diseases

The spectrum of known monogenic inborn errors of immunity is growing, with certain disorders underlying a specific and narrow range of infectious diseases. These disorders reveal the core mechanisms by which these infections occur in various settings, including inherited and acquired immunodeficiencies, thereby delineating the essential mechanisms of protective immunity to the corresponding pathogens. These findings also have medical implications, facilitating diagnosis and improving the management of individuals at risk of disease.

Mechanism and nanotechnological-based therapeutics for tolerance and resistance of bacterial biofilms

Bacterial biofilms are one of the most relevant drivers of chronic and recurrent infections and a significant healthcare problem. Biofilms were formed by cross-linking of hydrophobic extracellular polymeric substances (EPS), such as proteins, polysaccharides, and eDNA, which were synthesized by bacteria themselves after adhesion and colonization on biological surfaces. They had the characteristics of dense structure and low drug permeability, leading to tolerance and resistance of biofilms to antibiotics and to host responses. Within a biofilm, microbial cells show increased tolerance to both immune system defense mechanisms and antimicrobials than the same cells in the planktonic state. It is one of the key reasons for the failure of traditional clinical drug to treat infectious diseases. Currently, no drugs are available to attack bacterial biofilms in the clinical setting. The development of novel preventive and therapeutic strategies is urgently needed to allow an effective management of biofilm-associated infections. Based on the properties of nanomaterials and biocompatibility, nanotechnology had the advantages of specific targeting, intelligent delivery and low toxicity, which could realize efficient intervention and precise treatment of biofilm-associated infections. In this paper, the mechanisms of bacterial biofilm resistance to antibiotics and host response tolerance were elaborated. Meanwhile, This paper highlighted multiple strategies of biofilms eradication based on nanotechnology. Nanotechnology can interfere with biofilm formation by destroying mature biofilm, modulating biofilm heterogeneity, inhibiting bacterial metabolism, playing antimicrobial properties, activating immunity and enhancing biofilm penetration, which is an important new anti-biofilm preparation. In addition, we presented the key challenges still faced by nanotechnology in combating bacterial biofilm infections. Utilization of nanotechnology safely and effectively should be further strengthened to confirm the safety aspects of their clinical application.

Global meta-analysis of short-term associations between ambient temperature and pathogen-specific respiratory infections, 2004 to 2023

BackgroundAmbient temperature may affect respiratory health, while the temperature sensitivity of respiratory infections may be pathogen-dependent.AimsWe sought to explore pathogen-specific associations between ambient temperature and respiratory infections.MethodsWe searched nine databases for a random-effects meta-analysis to pool the relative risk (RR) of respiratory infection by pathogen per 1° C temperature rise, compared to populations unexposed to the same temperature. We conducted pathogen-specific analyses, sensitivity analyses, subgroup analyses and meta-regression.ResultsA total of 137 studies were eligible for meta-analysis. The pooled and single-study estimates revealed that the incidence of respiratory syncytial virus (RR = 0.14; 95% confidence interval (CI): 0.09-0.23), influenza virus (IV) (RR = 0.40; 95% CI: 0.27-0.61), human metapneumovirus (RR = 0.48; 95% CI: 0.32-0.73), human coronavirus (HCoV) (RR = 0.21; 95% CI: 0.07-0.61) and SARS-CoV-2 (RR = 0.52; 95% CI: 0.35-0.78) decreased per 1° C temperature rise, while that of human parainfluenza virus (HPIV) (RR = 2.35; 95% CI: 1.46-3.77), human bocavirus (HBoV) (RR = 1.86; 95% CI: 1.04-3.32) and MERS-CoV (RR = 1.05; 95% CI: 1.04-1.07) increased. The risk of infection was lower for IVA, IVB, HCoV-229E and HCoV-OC43, while HPIV-3, and HBoV-1 were at increased risk. The risk of Streptococcus pyogenes pharyngitis (RR = 0.46; 95% CI: 0.30-0.69) decreased per 1° C temperature rise, while Pseudomonas aeruginosa (RR = 1.04; 95% CI: 1.03-1.05) and Legionella pneumophila infections (RR = 2.69; 95% CI: 1.11-6.53) increased.ConclusionsTemperature sensitivity of respiratory infections can vary with the specific pathogen type and subtype that causes the infection. As the climatic conditions will become warmer, public health policy makers should act to develop pathogen adaptation strategies.

Peptide Double-Stapling and Arginine N-Glycosylation Triggered the Development of Therapeutic Antimicrobial Peptides Capable of Killing Drug-Resistant Bacteria in Mice

Antimicrobial peptides SAAP-148 exhibited excellent antimicrobial activities but suffered from inherent disadvantages, including cytotoxicity and poor proteolytic stability. Herein, we developed a novel strategy combining one unique silver-catalyzed solid-phase glycosylation-enabled arginine N-glycosylation strategy and all-hydrocarbon peptide double-stapling, and five-round peptide libraries were rationally constructed containing over 50 stapled and/or arginine N-glycosylated peptides. SLP-51 consisting of two introduced all-hydrocarbon staples and the C-terminal arginine glycosylation exhibited superior in vitro antimicrobial activities against drug-resistant Gram-positive or -negative clinical isolates. SLP-51 also exhibited improved proteolytic stability than the parent peptide SLP-0, and importantly, significantly weakened hemolysis. Experimental and modeling mechanism research indicated that SLP-51 exerted similar but stronger killing abilities by destroying the integrality of the bacterial membranes. In both skin wound and drug-resistant bacterial pneumonia models, SLP-51 showcased a potent therapeutic effect in treating both MRSA and Klebsiella pneumoniae infection in vivo and dramatical improvement of inflammatory injury.

Design, Synthesis, and Activity Evaluation of Novel Bifenamide Dual-Target Antibacterial Inhibitors and Carrier Based on Infectious Microenvironment

As the external environment worsens and immune function declines, Gram-negative bacterial infections are causing more and more serious pathological damage. In the study, three series of novel bifenamide dual-target (PD-L1/LpxC) compounds were designed using the skeleton growth method. Their chemical structures were synthesized, characterized, and evaluated for antibacterial activity. Among them, the compound 12b, which exhibited excellent dual-target (PD-L1/LpxC) inhibition ability, could efficiently block the biosynthesis of bacterial lipopolysaccharide (LPS), leading to pathogenic cell lysis and death. Moreover, the nanocomposite (NC-12b) was also prepared based on the infection microenvironment to improve the bioavailability and targeting of compound 12b. In vivo evaluation confirmed the dual functions of these components, including bacterial inhibition and immune activation, thereby synergistically accelerating the body's recovery process.

Evaluating infection risk associated with Staphylococcus aureus nasal carriage in blood donors: a prospective multicentre study in Denmark

OBJECTIVES

This study aims to investigate whether Staphylococcus aureus nasal carriage influences susceptibility to community-acquired S. aureus-associated infection and any other bacterial infection risk in healthy individuals.

METHODS

This prospective cohort study included blood donors aged 18-70 years between 2014 and 2021 in Denmark. A nasal swab cultivated for S. aureus defined carriage type (exposure) and infection endpoints were redeemed antibacterial prescriptions or International Classification of Diseases, tenth revision diagnoses from national registers. Adjusted incidence rate ratio (IRR) was estimated using Poisson regression for prescriptions, while Cox regression estimated hazard ratio for diagnoses.

RESULTS

Of 8738 included participants, 3503 (40.5%) were carriers. During a median follow-up of 3.8 years (interquartile range, 2.4-5.1), 1110 participants redeemed dicloxacillin/flucloxacillin and 1412 redeemed topical fusidic acid prescriptions, whereas 378 participants received hospital treatment for infections during 3.4 years (interquartile range, 1.9-4.6). Nasal carriers redeemed dicloxacillin and topical fusidic acid prescriptions more often than non-carriers (IRR, 1.40 [95% CI, 1.24-1.58] and IRR, 1.22 [1.10-1.36]; respectively). Participants who redeemed one dicloxacillin prescription were six times more likely to redeem another within 2 years. Among these, carriers had a higher incidence of redeeming additional dicloxacillin prescriptions than non-carriers (absolute risk, 19.0% vs. 12.9%, respectively; IRR 1.46 [1.17-1.84]). S. aureus nasal carriage was not associated with a higher risk of redeeming other antibacterial prescriptions nor with risk of hospital-treated S. aureus and any other bacterial infections.

DISCUSSION

In this study comprising healthy adults, nasal carriers with S. aureus exhibited an increased risk of redeemed dicloxacillin and topical fusidic acid prescriptions, but nasal carriage was not associated with any other types of bacterial infection. Findings suggest that nasal carriage elevates the burden of community-acquired S. aureus infections.

Ribosome phenotypes for rapid classification of antibiotic-susceptible and resistant strains of Escherichia coli

Rapid antibiotic susceptibility tests (ASTs) are an increasingly important part of clinical care as antimicrobial resistance (AMR) becomes more common in bacterial infections. Here, we use the spatial distribution of fluorescently labelled ribosomes to detect intracellular changes associated with antibiotic susceptibility in E. coli cells using a convolutional neural network (CNN). By using ribosome-targeting probes, one fluorescence image provides data for cell segmentation and susceptibility phenotyping. Using 60,382 cells from an antibiotic-susceptible laboratory strain of E. coli, we showed that antibiotics with different mechanisms of action result in distinct ribosome phenotypes, which can be identified by a CNN with high accuracy (99%, 98%, 95%, and 99% for ciprofloxacin, gentamicin, chloramphenicol, and carbenicillin). With 6 E. coli strains isolated from bloodstream infections, we used 34,205 images of ribosome phenotypes to train a CNN that could classify susceptible cells with 91% accuracy and resistant cells with 99% accuracy. Such accuracies correspond to the ability to differentiate susceptible and resistant samples with 99% confidence with just 2 cells, meaning that this method could eliminate lengthy culturing steps and could determine susceptibility with 30 min of antibiotic treatment. The ribosome phenotype method should also be able to identify phenotypes in other strains and species.

The effect of the dual scale surface topography of a surface-modified titanium alloy on its bactericidal activity against Pseudomonas aeruginosa

The rapid advancement of antibacterial nanostructured surfaces indicates that they will soon be integrated into real-world applications. However, despite notable progress, a comprehensive understanding of the antibacterial properties of nanostructures remains elusive, posing a critical barrier to the translation of this in vitro technology into practical applications. Among the numerous antibacterial nanostructures developed, nanowire structures play an important role due to their enhanced efficacy against bacteria and viruses and their ease of fabrication. Antibacterial nanowire structures exhibit the dual capability of lysing bacteria upon surface adhesion and mitigating bacterial colonization. The interplay of surface energy significantly influences bacterial adhesion, and macro surface roughness appears to be a pivotal determining factor. Macro-scale surface roughness not only modulates surface energy but also results in micro-scale topographical features that impact the bactericidal efficacy of nanowire structures. The integration of nanofabrication techniques on surfaces with macro-scale roughness yields multi-hierarchical micro- and nanoscale features, thereby possibly amplifying the bactericidal effect. Pseudomonas aeruginosa is an opportunistic pathogen that can cause serious infections. Moreover, this species has a higher risk of developing antibiotic resistance, which makes treatments for infections extremely difficult. Nanowire structures have demonstrated higher efficacy against P. aeruginosa species, making it a good alternative for fighting P. aeruginosa infections. This study demonstrates that heightened surface roughness amplifies the bactericidal potency of nanowire structures against P. aeruginosa bacterial species. The bactericidal effect reaches its maximum when the average surface roughness value is close to the bacterial cell size. This is contrary to the conventional assumption that the substrate surface must be smooth for the nanostructures to work, as the nanowire structures exhibit robust bactericidal efficacy, even when fabricated on rough surfaces. Therefore, the applicability of bactericidal nanostructures is expanded beyond smooth substrates. Consequently, these nanostructures can be effectively deployed on rugged industrial surfaces, broadening their potential impact across a diverse array of sectors. The widespread adoption of this nanotechnology promises transformative benefits not only to the medical sector but also to various industries. Moreover, by curbing bacterial infections, nanostructured surfaces hold the potential to reduce mortality rates and yield more direct economic dividends through waste reduction and enhanced safety. Ultimately, the widespread implementation of antibacterial nanowire technology stands poised to improve societal well-being and quality of life.

Synthesis of Cationic Cyclic Oligo(disulfide)s via Cyclo-Depolymerization: A Redox-Responsive and Potent Antibacterial Reagent

Antimicrobial peptides (AMPs) and synthetic topologically defined peptide mimics have been developed as alternatives to traditional small-molecule antibiotics. AMP mimetics arising from linear polymers used widely in preclinical studies have shown promise but have limited stability. Oligomers possessing cyclic topology have been proposed to have increased stability but remain understudied due to synthetic challenges and concerns over cytotoxicity. Herein, we present an efficient approach to prepare cationic, cyclic oligo(disulfide)s (CCOs) from lipoic acid derivatives. The CCOs are obtained in a one-pot cascade reaction of ring-opening polymerization preceding an in situ cyclo-depolymerization. CCOs are effective against a broad spectrum of bacteria, exhibiting a 5.43-log reduction in 5 min against Escherichia coli. They did not induce antimicrobial resistance during 24 successive passages in vitro. The cytotoxicity of CCOs is reduced by exploiting glutathione-triggered degradation. Further, fine-tuning of the cationic-to-hydrophilic ratio in CCOs has yielded improved stability in serum and a high selective index (HC50/MIC > 1280) against methicillin-resistant Staphylococcus aureus. In an infected wound rodent model, CCOs have shown substantial antibacterial potency against S. aureus, underscoring their therapeutic potential as a new class of antimicrobial agents.

Staphylococcus aureus infections in a highly complex clinic in Colombia. A longitudinal retrospective observational study

BACKGROUND

Antimicrobial resistance is a public health problem. Methicillin-resistant Staphylococcus aureus (MRSA) is one of the microorganisms most responsible for illness and death. The aim was to characterize the infections caused by S. aureus and to determine the factors associated with in-hospital mortality in patients treated in a highly complex clinic in Colombia.

METHODS

This was a longitudinal retrospective observational study of patients with culture-confirmed S. aureus infections who received hospital care between 2018 and 2023. Follow-up was carried out until the patients died or were discharged from the clinic. Descriptive, bivariate and multivariate analysis was performed.

RESULTS

A total of 361 patients were included; 62.6 % were men, and the mean age was 49.2 years. Most patients were diagnosed with skin and soft tissue infections (51.0 %) and bacteremia (25.5 %). The most used antibiotics were clindamycin (53.5 %) and vancomycin (42.7 %). A total of 46.3 % had MRSA infections and 25.8 % were resistant to clindamycin, 37.7 % of the patients received care in the intensive care unit, 33.2 % had sepsis, 19.1 % required invasive mechanical ventilation, and 13.9 % died. Higher Charlson comorbidity index (aOR:1.45; 95%CI:1.04-2.02), higher Pitt Bacteremia Score (aOR:1,72; 95%CI:1.21-2.46) and bacteremia (aOR:5.30; 95%CI:1.44-19.41) increased the probability of death. Those who were empirically managed with antibiotics that had coverage for MRSA (aOR:0.03; 95%CI:0.00-0.24) and higher levels of hemoglobin (aOR:0.75; 95%CI:0.65-0.87) had a lower risk of death.

CONCLUSION

MRSA infections are frequent, with significant resistance to clindamycin. The identification of variables associated with a higher risk of dying may be useful for establishing protocols in hospitals that reduce this outcome.

Enterobacter hormaechei replaces virulence with carbapenem resistance via porin loss

Pathogenic Enterobacter species are of increasing clinical concern due to the multidrug-resistant nature of these bacteria, including resistance to carbapenem antibiotics. Our understanding of Enterobacter virulence is limited, hindering the development of new prophylactics and therapeutics targeting infections caused by Enterobacter species. In this study, we assessed the virulence of contemporary clinical Enterobacter hormaechei isolates in a mouse model of intraperitoneal infection and used comparative genomics to identify genes promoting virulence. Through mutagenesis and complementation studies, we found two porin-encoding genes, ompC and ompD, to be required for E. hormaechei virulence. These porins imported clinically relevant carbapenems into the bacteria, and thus loss of OmpC and OmpD desensitized E. hormaechei to the antibiotics. Our genomic analyses suggest porin-related genes are frequently mutated in E. hormaechei, perhaps due to the selective pressure of antibiotic therapy during infection. Despite the importance of OmpC and OmpD during infection of immunocompetent hosts, we found the two porins to be dispensable for virulence in a neutropenic mouse model. Moreover, porin loss provided a fitness advantage during carbapenem treatment in an ex vivo human whole blood model of bacteremia. Our data provide experimental evidence of pathogenic Enterobacter species gaining antibiotic resistance via loss of porins and argue antibiotic therapy during infection of immunocompromised patients is a conducive environment for the selection of porin mutations enhancing the multidrug-resistant profile of these pathogens.

Rapid and relaying deleterious effects of a gastrointestinal pathogen, Citrobacter rodentium, on bone, an extra-intestinal organ

Enteropathogenic infections cause pathophysiological changes in the host but their effects beyond the gastrointestinal tract are undefined. Here, using Citrobacter rodentium infection in mouse, which mimics human diarrheal enteropathogenic Escherichia coli, we show that gastrointestinal infection negatively affects bone remodeling, leading to compromised bone architecture. Transmission of infection through fecal-oral route from Citrobacter rodentium-infected to non-infected mice caused bone loss in non-infected cage mates. Mice with B cell deficiency (Igh6-/- mice) failed to clear C. rodentium infection and exhibited more severe and long-term bone loss compared to WT mice. Unbiased cytokine profiling showed an increase in circulating tumor necrosis factor α (TNFα) levels following Citrobacter rodentium infection, and immunoneutralization of TNFα prevented infection-induced bone loss completely in WT and immunocompromised mice. These findings reveal rapid, relaying, and modifiable effects of enteropathogenic infections on an extraintestinal organ-bone, and provide insights into the mechanism(s) through which these infections affect extraintestinal organ homeostasis.

Major blood stream infection-causing bacterial pathogens, antimicrobial resistance patterns and trends: a multisite retrospective study in Asmara, Eritrea (2014-2022)

BACKGROUND

An important knowledge gap exists on the epidemiology of blood stream infections (BSIs) in low-middle-income countries (LMICs). In this retrospective analysis, we evaluated the etiology, antimicrobial resistance (AMR) and trends of BSIs in Eritrea.

METHODS

The study reviewed 9-year records (January 2014- December 2022) of 3153 patients with blood culture results available in the National Health Laboratory (NHL) archives. Relevant data included age, sex, hospital/care center, and year.

RESULT

During the surveillance period, we examined data from 3153 patients (1797 (57.0%) men vs. 1356 (43.0%) females, and 1.2 years (Q1: 0.01 months - Q3: 15 years). Of the samples submitted, 1026 (35.5%) samples were positive for the presence of pathogens (663(64.6%) pathogens vs. 363 (35.4%)) potential contaminants. In decreasing frequency, the most common isolates were: Coagulase-negative Staphylococcus (CoNs), 189 (28.6%); Klebsiella spp., 120 (18.2%); Escherichia coli, 66 (10.0%); Citrobacter spp., 48 (7.3%); Staphylococcus aureus, 47(7.1%); Pseudomonas aeruginosa, 34 (5.1%); and Salmonella spp., 33(5.1). The relative prevalence of BSIs changed somewhat over time (p-value < 0.001) with the isolation of multiple isolates trending upward from 2018 and onwards. Additional findings included the likely presence of extended spectrum beta lactamase (ESBL), high frequency of methicillin resistant Staphylococcus aureus (MRSA) (37(80.4%) and high rate of resistance to gentamicin (363(62.5%) and fluoroquinolones. Furthermore, the multiple antimicrobial resistances (MAR) index was relatively high (mean = 0.55, SD: ±0.23) with wide species-level variation. In a related density cluster analysis, we demonstrated a time-dependent increase in the diversity of resistotypes.

CONCLUSION

This study highlights the considerable health burden of AMR/or MDR in BSIs in Eritrea. Additionally, it underscores the urgent need for enhanced laboratory capacity, surveillance, institutionalisation of antibiotic stewardship programs, and robust infection control programs in hospitals across the country. The need for multidisciplinary research was also highlighted.

A Rapid Molecular Detection Tool for Toxigenic M1UK Streptococcus pyogenes

BACKGROUND

The gradual replacement of the Streptococcus pyogenes M1global genotype by a newly emergent M1UK variant is a global public health threat warranting increased surveillance. M1UK differs from progenitor M1global genotype by 27 single-nucleotide polymorphisms and is characterized by increased speA superantigen expression in vitro.

METHODS

An allele-specific real-time polymerase chain reaction assay was developed for the rapid detection of M1UK strains. The assay was used in combination with whole genome sequencing to determine emm (sub)type distribution for 51 invasive (n = 9) and noninvasive (n = 42) S pyogenes clinical isolates.

RESULTS

Emm1 was the most prevalent S pyogenes emm serotype (n = 11) in this set of clinical isolates, with M1UK being the dominant emm1 genotype (4/5 invasive, 3/6 noninvasive isolates). The assay accurately detected M1UK strains. Whole genome sequencing revealed continued presence of Australian M1UK sublineages associated with epidemic scarlet fever-causing S pyogenes in Asia.

CONCLUSIONS

Our study establishes a suitable target for detection of the toxigenic M1UK and confirms the maintenance of M1UK strains in Queensland, Australia. This assay can be deployed in laboratories and provides a valuable, cost-effective tool to enhance surveillance of the expanding M1UK clone.

Biomedical Engineering on Smart Polymeric Nanoparticle-Hydrogel Platforms for Efficient Antibiotic Delivery against Bacterial-Infected Wounds

The rising incidence of bacterial infections poses a significant challenge to global public health. The development of safe and effective antibacterial treatment strategies is an urgent need in the field of biomedicine. In this work, we developed a smart nanoparticle-hydrogel platform to address bacterial infections in wounds. Rifampicin-loaded chitosan-functionalized nanoparticles (R-CNP) could break bacterial barriers and enhance antibiotic internalization. R-CNP reduced the minimum inhibitory concentration of rifampicin against Staphylococcus aureus and greatly enhanced the bactericidal effect of rifampicin. Furthermore, R-CNP was incorporated into thermosensitive hydrogels (HG) to construct HG(R-CNP) for enhanced antibiotic accumulation and wound protection. In the mouse model with a bacterial-infected wound, treatment with R-CNP reduced the bacterial content by 98.5% as compared to treatment with free rifampicin. Therefore, this smart nanoparticle-hydrogel platform constructed by FDA-approved or natural polymers, offers significant therapeutic efficacy on bacterial-infected wounds, showing great promise for clinical translation.

Prediction of antimicrobial susceptibility of pneumococci based on whole-genome sequencing data: a direct comparison of two genomic tools to conventional antimicrobial susceptibility testing

Determination of antimicrobial resistance (AMR) in pneumococcal isolates is important for surveillance purposes and in a clinical context. Antimicrobial susceptibility testing (AST) of pneumococci is complicated by the need for exact minimal inhibitory concentrations (MICs) of beta-lactam antibiotics. Two next-generation sequencing (NGS) analysis tools have implemented the prediction of AMR in their analysis workflow, including the prediction of MICs: Pathogenwatch (https://pathogen.watch/) and AREScloud (OpGen). The performance of these tools in comparison to phenotypic AST following EUCAST guidelines is unknown. A total of 538 Streptococcus pneumoniae isolates were used to compare both tools with phenotypic AST for penicillin, amoxicillin, cefotaxime/ceftriaxone, erythromycin, trimethoprim-sulfamethoxazole, and tetracycline. Disk diffusion was performed for all isolates, and broth microdilution was performed for isolates with reduced beta-lactam susceptibility. Demultiplexed FASTQ files from Illumina sequencing, covering the whole genome of pneumococci, were used as input for the NGS tools. Categorical agreement (CA), major error (ME), and very major error (VME) rates were calculated. For beta-lactam antibiotics, CA was high (>94%) associated with none or only one ME and VME (<1%). For erythromycin and tetracycline, CA was >93% for predictions by AREScloud, while for Pathogenwatch, this ranged around 88%. For trimethoprim-sulfamethoxazole, CA was for both tools <86%. High VME rates were observed for erythromycin and tetracycline, higher for Pathogenwatch (53.6% and 47.0%, respectively) compared to AREScloud (14.3% and 19.1%, respectively). Both tools performed excellently despite the complexity of predicting beta-lactam resistance in pneumococci. Further optimization and validation are needed for non-beta-lactams since high (very) major error rates were observed.

Re-Emergence of Bacteriophages and Their Products as Antibacterial Agents: An Overview

Microbes possess diverse genetic and metabolic traits that help them withstand adverse conditions. Microbial pathogens cause significant economic losses and around 7.7 million human deaths annually. While antibiotics have historically been a lifesaving treatment, their effectiveness is declining due to antibiotic-resistant strains, prompting the exploration of bacterial predation as an alternative. Bacteriophages (BPhs) have reemerged as antibacterial agents, offering advantages over antibiotics, such as (i) high specificity, (ii) self-replication, and (iii) strong killing capacity. This review explores BPh- and enzyme-based antibacterial strategies for infectious disease treatment, discussing phage-antibiotic synergy, the risks of BPh resistance, and the role of quorum sensing in BPh therapy.

Immunostimulatory effects of isomalto/malto-polysaccharides via TLR2 and TLR4 in preventing doxycycline-induced cytokine loss

Isomalto/malto-polysaccharides (IMMPs) are α-glucans with prebiotic potential used as food ingredients. However, their ability to exert direct cellular effects remains unknown. IMMPs may enhance immunity by activating toll-like receptors (TLRs), key for defense against pathogens. Doxycycline is an antibiotic that requires an effective immune function but paradoxically has immune-attenuating effects by reducing TLR2 activity, potentially increasing antibiotic needs. We hypothesize that IMMPs are recognized by various cell surface TLRs, leading to the activation of the NF-κB signaling pathway. Furthermore, IMMPs' immune-stimulating effect could prevent the doxycycline-induced reduction of TLR2 activity in immune cells. IMMPs activated TLR2, increasing NF-κB signaling by 3.42- and 6.37-fold at 1 and 2 mg/mL, respectively. TLR4 activation increased 5.47-, 7.39-, and 8.34-fold at 0.5, 1, and 2 mg/mL. IMMPs enhanced IL-8, TNFα, and IL1-RA production in THP-1 monocytes. Additionally, preincubation of macrophages with IMMPs enhanced cytokine production and partially prevented doxycycline-induced cytokine reduction in response to TLR2 activation. Molecular docking analyses support IMMPs and doxycycline binding to these TLRs. These findings suggest that IMMPs stimulate immunity via TLR2 and TLR4, partially mitigating doxycycline's adverse effects. This provides a dietary strategy to enhance pathogen clearance, reduce antibiotic needs, and support immune health.

Urban waste piles are reservoirs for human pathogenic bacteria with high levels of multidrug resistance against last resort antibiotics: A comprehensive temporal and geographic field analysis

Inadequate waste management and poor sanitation practices in Low- and Middle-Income Countries (LMICs) leads to waste accumulation in urban and peri-urban residential areas. This increases human exposure to hazardous waste, including plastics, which can harbour pathogenic bacteria. Although lab-based studies demonstrate how plastic pollution can increase the persistence and dissemination of dangerous pathogens, empirical data on pathogen association with plastic in real-world settings are limited. We conducted a year-long spatiotemporal sampling survey in a densely populated informal settlement in Malawi, quantifying enteric bacterial pathogens including ESBL-producing E. coli, Klebsiella pneumoniae, Salmonella spp., Shigella spp., and Vibrio cholerae. Culture-based screening and molecular approaches were used to quantify the presence of each pathogen, together with the distribution and frequency of resistance to antibiotics. Our data indicate that these pathogens commonly associate with urban waste materials. Elevated levels of these pathogens precede typical infection outbreaks, suggesting that urban waste piles may be an important source of community transmission. Notably, many pathogens displayed increased levels of AMR, including against several 'last resort' antibiotics. These findings highlight urban waste piles as potential hotspots for the dissemination of infectious diseases and AMR and underscores the need for urgent waste management interventions to mitigate public health risks.

Chemical Characterization and Antibiotic-Enhancing Activity of the Essential Oils of Propolis of Melipona quadrifasciata quadrifasciata

This study investigated the chemical composition and potential antibacterial activity of the essential oils from the propolis of Melipona quadrifasciata quadrifasciata (MQP) in samples collected from the cities of Paranaguá and Guaratuba, Paraná, Brazil, during summer and winter. The chemical composition of the oils was analyzed by GC-MS, and their minimum inhibitory concentration (MIC) was determined against standard ATCC strains and some clinical isolates (Escherichia coli 06 and Staphylococcus aureus 10). The essential oils' MICs were determined using microdilution in 96-well plates and showed no significant antibacterial activity (MIC ≥ 1024 μg/mL) when used alone. However, the essential oils enhanced the action of norfloxacin, gentamicin, and ampicillin, especially against S. aureus 10. The chemical analysis identified 68 compounds, with β-bisabolene and β-caryophyllene as the predominant constituents. Subsequently, the antibiotic-enhancing activity against the clinical isolates was evaluated. The composition of the MQP oils varied according to seasonality and location, influenced by the microclimates of the cities. The results highlight the importance of MQP oils in enhancing antibiotic activity, particularly against Gram-positive bacteria, despite the lack of significant standalone antibacterial activity.

Evolution of pathogenic Escherichia coli harboring the transmissible locus of stress tolerance: from food sources to clinical environments

Escherichia coli (E. coli) carrying the transmissible locus of stress tolerance (tLST) are able to overcome numerous environmental challenges. In our in-silico study, we aimed to characterize tLST in terms of its variants in 793 genomes of E. coli from Brazil originating from food, environmental and clinical (animal and human) sources, and to perform a temporal analysis in order to identify the historical moment of its emergence. We also analyzed the presence of two Yersinia high pathogenicity island (HPI) variants in E. coli genomes, describing other genes and accessory for resistance, persistence, mobile elements (plasmids) and sequence types. The prevalence of the tLST was 10% in E. coli from Brazil, predominantly observed in milk-originating genomes, within the prevalent tLSTCP010237 variant. In E. coli from other sources (clinical/environmental), only part of the tLST was present. Remarkably, our temporal analysis pinpointed the emergence of tLST back to around 1914, coinciding with major societal events. Regarding virulence genes, we found a prevalence of 38.5% for HPI of Y. pestis across genomes from all sources. Our global analysis also showed a high diversity of other virulence genes for milk E. coli (+ 100 genes). These genomes also stood out from the overall metadata for presenting a greater variety of resistance genes to other stresses, such as metals, biocides and acids, as well as persistence genes (biofilm formation). This study demonstrated the historical background of E. coli with tLST genes dating back more than 100 years, and the acquisition of a wide range of virulence and resistance genes that allow it to circulate in different environments: from food to clinic or from clinic to food, making this bacterium a pathogen that requires rigorous surveillance and strategic interventions to mitigate potential risks.

Integrated bacterial cell lysis and DNA extraction using paper-based isotachophoresis

Bacterial infections remain a global threat, particularly in low-resource settings, where access to accurate and timely diagnosis is limited. Point-of-care nucleic acid amplification tests have shown great promise in addressing this challenge. However, their dependence on complex traditional sample preparation methods remains a major challenge. To address this limitation, we present a paper-based sample preparation device that integrates bacterial cell lysis, DNA purification, and concentration using an electrokinetic technique called isotachophoresis (ITP). This is the first device that (i) integrates electrochemical bacterial lysis with ITP and (ii) demonstrates the focusing of whole bacterial genomic DNA (gDNA) in paper. Characterization with buffers showed that the paper-based ITP sample preparation module (p-ITPrep) concentrated bacterial gDNA with an average concentration factor of 12×, and DNA could be extracted from a sample containing as few as 102 CFU mL-1Mycobacterium smegmatis (Msm). From complex biological matrices - human saliva, human blood serum, and artificial urine - p-ITPrep extracted DNA from samples containing 102 CFU Msm per mL saliva or artificial urine and 103 CFU Msm per mL serum within 20 min. The extraction procedure involved only 3 user steps, in contrast to conventional solid phase extraction kits that require more than 10 user steps. p-ITPrep may provide a simple, inexpensive, and versatile alternative to conventional multi-step nucleic acid extraction protocols for point-of-care diagnostics.

The Derivative Difluoroboranyl-Fluoroquinolone "7a" Generates Effective Inhibition Against the S. aureus Strain in a Murine Model of Acute Pneumonia

During the last decades, most bacterial strains have become increasingly resistant to antibiotics. This led the WHO to declare a global emergency in 2017 and urge the development of new active compounds. Some families of antibiotics still show high antibacterial efficacy, as is the case of fluoroquinolones, which have a broad spectrum of action. For this reason, our research group derived several compounds from fluoroquinolones, selecting a compound with good antibacterial activity for further evaluations, a difluoroboranil-fluoroquinolone complex labeled 7a. Antibacterial activity was evaluated using the Kirby-Bauer method against S. aureus (clinical isolate HGZ2201#ID). The MIC and MBC were obtained by macrodilutions and reseeding. In vivo antimicrobial activity was evaluated in a Balb/c mouse model infected intratracheally with S. aureus and subsequently treated with ciprofloxacin or 7a (80 mg/kg/day) for five days. A mean of 8.55 ± 0.395 cm2 inhibition area was observed using 7a, while ciprofloxacin generated a mean inhibition of 7.86 ± 0.231 cm2. Compound 7a showed a MIC and MBC of 0.25 μg/mL. This reduced the generation of pneumonic lung tissue to 5.83%, while the untreated infected group generated 60.51% of pneumonic tissue. Compound 7a proved to be an antimicrobial agent capable of inhibiting the in vitro development of S. aureus. Furthermore, 7a showed effectiveness in decreasing the progression of acute pneumonia induced by S. aureus in a murine model.

Epidemiological trends and predictions of urinary tract infections in the global burden of disease study 2021

Urinary tract infections (UTIs) are prevalent; however, comprehensive and current epidemiological data remain scarce. This study examined the global, national, and regional burden of UTIs by sex, age, and socio-demographic index (SDI) from 1990 to 2021. The 2021 Global Burden of Disease study included age-standardised incidence rate (ASIR), age-standardised prevalence rate (ASPR), age-standardised death rate (ASDR), and age-standardised disability-adjusted life years rate (ASDAR). The estimated annual percentage change was used to depict temporal trends, whereas Pearson correlation analysis explore its correlation with the human development index (HDI), the SDI, and age-standardised rates (ASRs). An autoregressive integrated moving average model forecasted the UTI burden trends. From 1990 to 2021, the number of UTI cases increased by 66.45%, reaching 4.49 billion cases, with an ASIR of 5,531.88 per 100,000 population. The greatest incidence of UTIs was seen in women and older adult men. Tropical Latin America and low-middle SDI regions exhibited the highest ASIR, ASPR, ASDR, and ASDAR, while East Asia showed the lowest. ASDR and ASDAR decreased with higher SDI levels. ASR and HDI were weakly positively correlated with ASDR and ASDAR. ASIR, ASPR, and ASDAR are projected to increase until 2050. The global burden of UTIs is rising and is influenced by geographical location, age, sex, and economic development, crucial for guiding medical practices and forming relevant policies.

Nasopharyngeal Carriage, Antimicrobial Resistance, and Serotype Distribution of Streptococcus pneumoniae in Children Under Five in Lebanon: Baseline Data Prior to PCV13 Introduction

BACKGROUND

The nasopharyngeal carriage of Streptococcus pneumoniae can be the source of transmission between humans and the starting step towards invasive pneumococcal diseases. Data on the carriage of pneumococci in children before and after the pneumococcal conjugate vaccines (PCV) integration in a country are essential for monitoring any change in pneumococcal carriage serotypes and their antimicrobial-resistance profiles.

METHODS

We investigated the epidemiology of S. pneumoniae carriage among children younger than five years old in Tripoli, Lebanon, in 2016, the same year of integration of PCV13 in the country's Expanded Program on Immunization.

RESULTS

Of 104 participating children, 57 (54.8%) gave a positive culture for S. pneumoniae. Antimicrobial susceptibility testing revealed that 26.3% of isolates were multidrug-resistant. Resistance was detected mainly against oxacillin (77.2%), tetracycline (29.8%), erythromycin (22.8%), trimethoprim-sulfamethoxazole (22.8%), clindamycin (19.3%), minocycline (19.3%), and teicoplanin (1.8%). Serotyping analysis identified 14 distinct serotypes, with only 31.3% and 50% of isolates corresponding to vaccine serotypes covered by PCV13 and PCV20, respectively. The most common serotypes were 11A, 19F, 23A, and those of serogroup 24 (Sg24) accounted for 37.5% of the serotyped isolates.

CONCLUSIONS

Our findings have revealed the circulation of a pool of pneumococci isolates with high levels of antibiotic resistance and different degrees of likelihood of causing invasive diseases in children under five years old in Tripoli in 2016. The overall limited PCV13 vaccine coverage in this study highlighted the need for vaccines with greater coverage in the immunization programs in Lebanon. Longitudinal national studies investigating the carriage of pneumococci in children are required to further assess the impact of the PCV vaccine on pneumococci carriage in children and steer new vaccine development.

Copper doped magnetic vortex nanoring based nanotherapeutics for bacterial infection tri-therapy: interplay of magnetic hyperthermia, chemodynamic therapy and photothermal therapy

Infectious bacteria pose an increasing threat to public health, and hospital-acquired bacterial infections remain a significant challenge for wound healing. In this study, we developed an advanced nanoplatform utilizing copper doped magnetic vortex nanoring coated with polydopamine (Cu-MVNp) based nanotherapeutics for bacterial infection tri-therapy. This multifunctional nanoplatform exhibits remarkable dual-stimulus thermogenic capabilities and Fenton-like peroxidase activity. Exposure to an alternating magnetic field (AMF) and near-infrared (NIR) light allows the nanoring to elevate environmental temperatures through hysteresis losses and the non-radiative decay effects of the PDA coating. At a concentration of 150 μg mL-1, Cu-MVNp increases the temperature by 18.2 °C under an AMF, achieving a specific absorption rate (SAR) of 640.9 W g-1. On the other hand, under 808 nm NIR irradiation, the temperature rises by 42.6 °C, with a photothermal conversion efficiency of 46.45%. Furthermore, by incorporating copper ions (Cu), which can damage cell membranes themselves, Cu-MVNp was endowed with Fenton-like functions and can catalyze the formation of hydroxyl radicals (˙OH) from low concentrations (1 mM) of hydrogen peroxide (H2O2), thus enhancing the effectiveness of chemodynamic therapy (CDT). Cu-MVNp exhibits significant antibacterial efficacy, achieving notable kill rates against E. coli and S. aureus, with enhanced effects under NIR and nearly complete eradication with an AMF. In vivo tests using a mouse wound model confirm its potent bactericidal properties and good biocompatibility. The Cu-MVNp nanoring shows promise as an antibacterial treatment, potentially effective at inhibiting bacterial growth.

Novel steroidal β-carboline derivatives as promising antibacterial candidates against methicillin-resistant Staphylococcus aureus

A novel series of steroidal β-carboline quaternary ammonium derivatives (SCQADs) derived from natural cholic acid and its derivatives was designed, synthesized and biologically evaluated against four Gram-positive bacteria for the first time. Most of these derivatives exhibited promising antibacterial activity against the tested strains, particularly, compound 21g displayed strong antibacterial activity against MRSA (MIC = 0.5-1 μg/mL) with low cytotoxicity. Meanwhile, derivative 21g was able to quickly kill Gram-positive bacteria within 0.5 h without inducing bacterial resistance. Preliminary mechanistic explorations indicated that compound 21g destroyed bacterial cell membranes to exert its antibacterial effects. Moreover, 21g exhibited high in vivo efficacy and high survival protection in a mouse skin abscess model. These findings suggested that compound 21g has great potential to develop as an antibacterial agent.

Bloodstream infections at a tertiary hospital in the Gambia - a one-year retrospective study

INTRODUCTION

Antimicrobial resistance is a significant global health concern, particularly in western Sub-Saharan Africa. This study describes causes of bloodstream infections and antimicrobial resistance at a tertiary hospital in The Gambia.

METHODS

This retrospective analysis included all blood cultures performed at the Edward Francis Small Teaching Hospital, Banjul, The Gambia, from September 2022 to August 2023. Blood culture positivity-rates and pathogens were described. Antimicrobial susceptibility testing was performed using disk diffusion following the Clinical & Laboratory Standards Institute guidelines.

RESULTS

A total of 645 patients had blood cultures drawn during the study period with 260 (40%) positive results. Contaminants were identified in 28 cases (4%). The majority were drawn from neonatal or paediatric patients (360/645, 56%) and overall primarily in intensive care units (406/645, 63%). The median age was 3 years (interquartile range 0-31 years) and 46% were female. The most common pathogens were Staphylococcus aureus 106/260 (41%), Klebsiella spp. 41/260 (16%), other bacteria within the Enterobacterales order 33/260 (13%), Pseudomonas spp. 22/260 (8%) and Acinetobacter spp. 19/260 (7%). Methicillin-resistant S. aureus (MRSA) was seen in 34/58 (59%) tested. Extended-spectrum beta-lactamases (ESBL) were seen in 36/40 (90%) of Klebsiella spp. and in 16/28 (57%) of other bacteria within the Enterobacterales order. Acquired antibiotic resistance, beyond wild-type, was reported in 17/20 (85%) of Pseudomonas spp. and 16/19 (84%) of Acinetobacter spp.

CONCLUSION

Overall, blood culture positivity rates were high, indicating restrictive testing suggesting that sample collection were restricted to mainly critically ill, neonatal or paediatric patients. Nonetheless, our data suggests a high proportion of bloodstream infections due to multi-drug resistant pathogens, including MRSA and ESBL-Enterobacterales. Importantly, generalisability of findings beyond this tertiary hospital setting remains restricted. However, our findings demonstrate a need for improved diagnostic stewardship and ongoing surveillance to provide robust evidence-based data to inform antimicrobial resistance interventions.

Deciphering antibiotic resistance genes and plasmids in pathogenic bacteria from 166 hospital effluents in Shanghai, China

Although previous studies using phenotypic or metagenomic approaches have revealed the patterns of antibiotic resistance genes (ARGs) in hospital effluents in local regions, limited information is available regarding the antibiotic resistome and plasmidome in human pathogenic bacteria in hospital effluents of megacity in China. To address this knowledge gap, we analyzed effluent samples from 166 hospitals across 13 geographical districts in Shanghai, China, using both cultivation-based approaches and metagenomics. A total of 357 strains were isolated from these samples, with the predominant species being Escherichia coli (n = 61), Aeromonas hydrophila (n = 57), Klebsiella pneumoniae (n = 48), and Aeromonas caviae (n = 42). Those identified indicator bacteria were classified into biosafety level 1 (BSL-1, 60 %) and BSL-2 (40 %). We identified 1237 ARG subtypes across 22 types, predominantly including beta-lactam, tetracycline, multidrug, polymyxin, and aminoglycoside resistance genes, using culture-enriched phenotypic metagenomics. Mobile genetic elements such as plasmids, transposons (tnpA), integrons (intI1), and insertion sequences (IS91) were abundant. We recovered 135 plasmids classified into mobilizable (n = 94) and non-mobilizable (n = 41) types. Additionally, 80 metagenome-assembled genomes (MAGs) were reconstructed from the hospital effluents for the assessment of ARG transmission risks, including genes for last-line antibiotics such as blaNDM, blaKPC, blaimiH, and mcr. This study is the first to comprehensively characterize and assess the risk of antimicrobial resistance levels and plasmidome in the hospital effluents of China's megacity, providing city-wide surveillance data and evidence to inform public health interventions.

Design, synthesis, and biological evaluation of steroidal indole derivatives as membrane-targeting antibacterial candidates

Rational modification of natural products plays a key role in drug discovery. Herein, a series of steroidal indole derivatives containing various substituents and steroidal skeletons were designed and synthesized with classical Fischer indole synthesis as a key step in an efficient synthetic route for the first time. The in vitro antibacterial activity of all the synthesized derivatives was evaluated against four Gram-positive strains including three Methicillin-Resistant Staphylococcus aureus. Compound 11e displayed the most potent antibacterial activity (MIC = 1-2 μg/mL) with low cytotoxicity and hemolytic activity. Derivative 11e displayed more rapid bactericidal kinetic than vancomycin in the time-kill study and was less likely to induce bacterial resistance. Moreover, the preliminary antibacterial mechanism explorations indicated that compound 11e could effectively inhibit biofilm formation, promote the accumulation of reactive oxygen species, decrease bacterial metabolism, and destroy bacterial cell membranes to exert its antibacterial effects. The study of in vivo antibacterial activity suggested that compound 11e could significantly reduce the bacteria counts in a mouse subcutaneous infection model. These findings provided a bright hope for steroidal indole derivatives as promising antibacterial candidates to settle drug resistance.

Staphylococcus aureus-specific TIGIT+ Treg are present in the blood of healthy subjects - a hurdle for vaccination?

Staphylococcus aureus poses an enormous burden of morbidity and mortality worldwide. Making an efficacious vaccine has however proven extremely challenging. Due to colonizing interactions, pre-existing S. aureus-specific CD4+ T cells are often found in the human population and yet a detailed characterization of their phenotypes and how they might in turn impact vaccine efficacy are thus far unknown. Using an activation induced marker assay to sort for S. aureus-specific CD4+ T cells in an effector function-independent manner, single cell transcriptomic analysis was conducted. Remarkably, S. aureus-specific CD4+ T cells consisted not only of a broader spectrum of conventional T cells (Tcon) than previously described but also of regulatory T cells (Treg). As compared to polyclonally-activated CD4+ T cells, S. aureus-specific Tcon were enriched for the expression of the Th17-type cytokine genes IL17A, IL22 and IL26, while higher percentages of S. aureus-specific Treg expressed the T Cell Immunoreceptor with Ig and ITIM domains (TIGIT), a pleiotropic immune checkpoint. Notably, the antagonistic anti-TIGIT mAb Tiragolumab increased IL-1β production in response to S. aureus in vitro. Therefore, these results uncover the presence of S. aureus-specific TIGIT+ Treg in the blood of healthy subjects that could blunt responses to vaccination and indicate TIGIT as a potential targetable biomarker to overcome pre-exposure-induced immunosuppression.