Pathogens

14 pages, 969 KB

Open AccessArticle

Contact Patterns Drive Age-Structured Transmission Dynamics and Seasonality of Scarlet Fever

by Jing He and Jijun Zhao

Pathogens 2026, 15(3), 296; https://doi.org/10.3390/pathogens15030296 - 9 Mar 2026

Background: Scarlet fever has seen a sharp increase in its reported incidence in China since 2011, and this study focuses on Shanghai as a representative setting to systematically investigate its transmission dynamics by analyzing age structure. It further identifies high-risk age groups and [...] Read more.

Background: Scarlet fever has seen a sharp increase in its reported incidence in China since 2011, and this study focuses on Shanghai as a representative setting to systematically investigate its transmission dynamics by analyzing age structure. It further identifies high-risk age groups and provides a theoretical foundation for prevention and non-pharmaceutical intervention strategies. Methods: We developed an SIR model that incorporates age structure and seasonality of transmission rate. In parameter estimation, the methodology of the partially observed Markov process framework is employed to derive results based on monthly data. The time-varying reproduction number

R_{0} (t)

is derived monthly from the next-generation matrix. Age-specific forces of infection are estimated to identify high-risk groups and quantify how school-term-driven contact patterns modulate transmissibility. Results: The force of infection peaked in children aged 7–9 years, whereas the force of infection was highest among adults aged 35–39 years. The seasonal amplitude for transmission among school-aged groups was 39% (95% CI: 37–41%). The estimated

R_{0} (t)

varied seasonally between 3.02 and 8.83. Conclusions: The transmission rate in Shanghai shows strong age heterogeneity and school-driven seasonality. Children aged 7–9 years are the highest-risk group, and interventions should target them during periods of high

R_{0} (t)

. Full article

(This article belongs to the Section Epidemiology of Infectious Diseases)

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21 pages, 3552 KB

Open AccessArticle

Long-Term Trends and Determinants of Tuberculosis Burden in China, 1990–2023: Insights from the Global Burden of Disease Study 2023

by Yingxing Wang, Guozhong He, Hoiman Ng, Chaoxi Niu, Rong Li, Furong Zhang, Ruimei Shi, Xingyue Dian, Qingping Ma and Zhong Sun

Pathogens 2026, 15(3), 295; https://doi.org/10.3390/pathogens15030295 - 8 Mar 2026

Abstract

Tuberculosis (TB) remains a major public health challenge in China despite substantial long-term progress. Using data from the Global Burden of Disease Study 2023, this study reassessed trends and determinants of TB burden in China from 1990 to 2023. Age-standardized incidence, mortality, and [...] Read more.

Tuberculosis (TB) remains a major public health challenge in China despite substantial long-term progress. Using data from the Global Burden of Disease Study 2023, this study reassessed trends and determinants of TB burden in China from 1990 to 2023. Age-standardized incidence, mortality, and disability-adjusted life year (DALY) rates were analyzed using estimated annual percentage change, age–period–cohort modeling, and demographic decomposition, with comparative risk assessment to quantify behavioral and metabolic contributions. Between 1990 and 2023, age-standardized incidence, mortality, and DALY rates declined by approximately 73.24%, 94.00%, and 92.40%, respectively. Negative net and local drift values indicated sustained reductions across age groups; however, the decline slowed after 2021, with a modest rebound in incidence. Since 2015, reductions in incidence have been more moderate than the pace required to achieve the 2035 End TB Strategy targets. Decomposition analysis demonstrated that improvements in age-specific rates were the primary drivers of long-term reductions, whereas demographic shifts—particularly population aging—partially offset these gains. The burden increasingly shifted toward older adults, and males consistently experienced higher rates than females. Tobacco and alcohol use contributed substantially to sex differentials, while undernutrition and metabolic disorders remained relevant risk factors. These findings indicate that China’s TB epidemic has entered a phase shaped by demographic aging and evolving risk structures, requiring sustained and adaptive control efforts. Full article

(This article belongs to the Special Issue Emerging and Re-Emerging Human Infectious Diseases)

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41 pages, 6789 KB

Open AccessReview

Promising Drug Repurposing Candidates Targeting Free-Living Amoebae: A Systematic and Critical Review of Laboratory-Based Evidence

by Beni Jequicene Mussengue Chaúque, Luiza Bernardes Chagas, Thaisla Cristiane Borella da Silva, Denise Leal dos Santos, Luciano Palmeiro Rodrigues, Lucile da Silva Lins Baía, Manoella Kessler Gomes Rodrigues, Guilherme Brittes Benitez, Thais Lemos Mendes, Hellen Kempfer Philippsen, Luciana Dalla Rosa, Fabrício Souza Campos, Marilise Brittes Rott, Régis Adriel Zanette and José Roberto Goldim

Pathogens 2026, 15(3), 294; https://doi.org/10.3390/pathogens15030294 - 7 Mar 2026

Abstract

Devastating or nearly invariably fatal infections caused by free-living amoebae (FLA), including Acanthamoeba keratitis (AK), granulomatous amoebic encephalitis (GAE), and primary amoebic meningoencephalitis (PAM), remain a significant public health concern, driven by increasing case numbers, geographic expansion, and the lack of approved, effective, [...] Read more.

Devastating or nearly invariably fatal infections caused by free-living amoebae (FLA), including Acanthamoeba keratitis (AK), granulomatous amoebic encephalitis (GAE), and primary amoebic meningoencephalitis (PAM), remain a significant public health concern, driven by increasing case numbers, geographic expansion, and the lack of approved, effective, and safe treatments. Despite decades of research, no new drugs have been successfully approved, highlighting the severe limitations of de novo drug development for these infections, particularly for GAE and PAM, largely due to the challenges of conducting clinical trials for these rare and rapidly lethal diseases. In this context, drug repurposing represents a cost-effective and promising strategy to accelerate therapeutic advances and overcome key bottlenecks of conventional drug development. Accordingly, we conducted a systematic review of in vitro studies and animal models of AK, GAE, and PAM reported in indexed databases to identify promising drug repurposing candidates against FLA infections. After screening 23,624 records, 112 studies were included in the analysis. Overall, 2726 drugs and drug combinations, spanning 865 pharmacological classes and approved for 565 therapeutic indications, were assessed for their repurposing potential. Among these, 166 compounds showed substantial trophocidal activity (≥IC₅₀) at potentially translatable concentrations (≤10 µM), including six with additional cysticidal activity. In vitro, four compounds were active against Balamuthia mandrillaris, 44 against Acanthamoeba spp. (three cysticidal), and 115 against Naegleria spp. (three cysticidal). In in vivo studies, sulfadiazine and rifampicin were effective as preventive or early monotherapies for GAE. For AK, the combination of polyhexamethylene biguanide, neomycin, and atropine, as well as voriconazole and nitazoxanide monotherapies, showed the greatest promise. In PAM, azithromycin alone or in combination with amphotericin B emerged as the most promising therapeutic options. Further studies are required to advance the clinical translatability of these findings. To the best of our knowledge, this work provides the first comprehensive and integrated synthesis of repurposable drug candidates against FLA infections. Full article

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13 pages, 719 KB

Open AccessArticle

Comparative Genome Analysis of Illumina, Nanopore, and Hybrid Approaches: A Case Study of the Aquaculture Isolate 160P

by Izzet Burcin Saticioglu, Janset Bozkurt and Muhammed Duman

Pathogens 2026, 15(3), 293; https://doi.org/10.3390/pathogens15030293 - 6 Mar 2026

Abstract

In this study, we comparatively assessed short-read (Illumina), long-read (Oxford Nanopore Technologies, ONT), and hybrid (Illumina + ONT) sequencing strategies for bacterial genome analysis using the aquaculture-derived isolate 160P. Genomic DNA was extracted and sequenced on Illumina paired-end and ONT long-read platforms, and [...] Read more.

In this study, we comparatively assessed short-read (Illumina), long-read (Oxford Nanopore Technologies, ONT), and hybrid (Illumina + ONT) sequencing strategies for bacterial genome analysis using the aquaculture-derived isolate 160P. Genomic DNA was extracted and sequenced on Illumina paired-end and ONT long-read platforms, and de novo assemblies were generated using SPAdes, Canu, Flye, and Unicycler under short-read-only, long-read-only, and hybrid workflows, followed by evaluation with QUAST assembly metrics. Among the tested approaches, the hybrid Unicycler assembly provided the highest contiguity, yielding seven contigs and a dominant 4.55 Mb contig consistent with near-complete chromosomal representation. Downstream analyses included functional genome annotation and in silico screening of antimicrobial resistance determinants (CARD), virulence-associated genes (VFDB), and secondary metabolite biosynthetic gene clusters (antiSMASH). Comparative genomic relatedness based on Average Nucleotide Identity (ANI) and digital DNA–DNA Hybridization (dDDH) indicated that 160P is most closely related to Aeromonas sobria CECT 4245^T yet falls below commonly applied species-level thresholds, supporting its placement as a genomically distinct lineage warranting further taxonomic investigation. Collectively, these findings underscore the value of hybrid sequencing for improving assembly continuity, enhancing annotation completeness, and strengthening taxonomic resolution in bacterial pathogen genomics. Full article

(This article belongs to the Special Issue Next-Gen Sequencing Advances Pathogen Research in Health, Agriculture & Environment)

17 pages, 827 KB

Open AccessArticle

Zoonotic Pathogens in Ixodes ricinus from an Urban Environment in Northern Slovakia

by Zuzana Cellengová, Blažena Hajdová, Andrea Schreiberová, Patrícia Petroušková, Maroš Kostičák and Alica Kočišová

Pathogens 2026, 15(3), 292; https://doi.org/10.3390/pathogens15030292 - 6 Mar 2026

Abstract

Ixodes ricinus is the most common and, epidemiologically speaking, the most important tick species in Slovakia, transmitting a wide range of zoonotic pathogens. The goal of the present study was to monitor selected tick-borne infectious agents in an urban environment in northern Slovakia [...] Read more.

Ixodes ricinus is the most common and, epidemiologically speaking, the most important tick species in Slovakia, transmitting a wide range of zoonotic pathogens. The goal of the present study was to monitor selected tick-borne infectious agents in an urban environment in northern Slovakia where the conditions for their occurrence and survival are typically unfavourable. Ticks were collected by the flagging method during the period from March to November 2024 in the city of Žilina in five urban locations characterized by high human activity and suitable conditions for tick–host interactions. A total of 264 ticks of Ixodes ricinus were collected (67 females, 85 males, and 112 nymphs). A molecular analysis confirmed the presence of Borrelia spp. in 34.5% of samples, while the most frequently detected species was Borrelia afzelii. The other detected species included zoonotic piroplasms Babesia microti and Babesia venatorum (1.5%), as well as the bacteria Anaplasma spp. (2.65%) and Rickettsia spp. (0.4%). In four ticks (1.5%), the presence of coinfection caused by multiple pathogens was detected. These results confirm that urban ecosystems located in the northern regions of Slovakia also provide significant reservoirs of zoonotic pathogens and impose a potential risk for public health. Full article

(This article belongs to the Special Issue Tick-Borne Threats in Europe: From Epidemiology to the Impact of Vaccination)

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23 pages, 2836 KB

Open AccessArticle

Therapeutic Drug Monitoring of GS-441524 in Cats with Feline Infectious Peritonitis: Pharmacokinetic Variability and Implications for Dose Optimization

by Stephen W. Cooke, Rachael Hammond and Danièlle A. Gunn-Moore

Pathogens 2026, 15(3), 291; https://doi.org/10.3390/pathogens15030291 - 6 Mar 2026

Abstract

Remdesivir (REM) and its parent drug, GS-441524 (GS-44), are used to treat cats with feline infectious peritonitis (FIP), resulting in a survival rate of circa 85% (range 77–96%). Cats suffering from FIP exhibit complex and variable clinical presentations, which will cause concurrent variations [...] Read more.

Remdesivir (REM) and its parent drug, GS-441524 (GS-44), are used to treat cats with feline infectious peritonitis (FIP), resulting in a survival rate of circa 85% (range 77–96%). Cats suffering from FIP exhibit complex and variable clinical presentations, which will cause concurrent variations in the pharmacokinetics (PK) of GS-44. In turn, this will vary the ability of target cells (monocytes and tissue macrophages) to absorb GS-44 in sufficient quantities to achieve optimal antiviral efficacy, resulting in full recovery. Sparse data exists to guide treatment regimens optimized for every presentation of FIP. Therapeutic Drug Monitoring (TDM) measured the GS-44 concentration in 728 blood samples from 263 cats undergoing treatment and generated 173 PK graphs. These identified individuals varied in their ability to absorb GS-44, leading to sub-optimal (11%) and supra-optimal (12%) dose-normalized plasma concentrations. Dosage alterations were suggested to guide subsequent dosages to ensure optimum GS-44 concentrations for individual cats (the clinical outcome report will be published separately). Proposed TDM target values are: area under the concentration vs. time curve (AUC), at least 220 µM·h, time per day that plasma concentration exceeds 3 µM, at least 23 h, time per day plasma concentration exceeds 10 µM, and at least 9 h. Full article

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13 pages, 990 KB

Open AccessArticle

Characterization of the Gastric Antrum Microbiome in Helicobacter pylori-Negative Individuals: Insights from a Greek Population Using 16S rRNA Next-Generation Sequencing

by Asimoula Kavvada, Georgia Gioula, Andreas Protopapas, Adonis A. Protopapas, Maria Christoforidi, Fani Minti, Christos Savopoulos and Maria Chatzidimitriou

Pathogens 2026, 15(3), 290; https://doi.org/10.3390/pathogens15030290 - 6 Mar 2026

Abstract

Background: Once considered a sterile organ, the human stomach is now known to harbor a diverse microbial community that may influence both gastric homeostasis and disease. While extensive research has been conducted worldwide, regional variation in the gastric microbiome remains insufficiently characterized. This [...] Read more.

Background: Once considered a sterile organ, the human stomach is now known to harbor a diverse microbial community that may influence both gastric homeostasis and disease. While extensive research has been conducted worldwide, regional variation in the gastric microbiome remains insufficiently characterized. This study aimed to describe the gastric antrum microbiome of Helicobacter pylori-negative Greek adults using 16S rRNA next-generation sequencing (NGS). Methods: Samples of gastric biopsies were obtained from patients undergoing gastroscopy at a tertiary hospital in Greece. H. pylori infection was excluded through a combination of bacterial culture and patient medical history. The final study group consisted of 9 subjects. Following DNA extraction, the 16S rRNA gene was sequenced on the Ion Torrent™ platform. Bioinformatic processing and statistical analyses were performed using the phyloseq, vegan, and ggplot2 R packages. Microbial composition, relative abundance, and alpha diversity (Shannon and Inverse Simpson indices) were evaluated at the genus level. Results: The gastric microbiome comprised 19 phyla, 150 families, 213 genera, and 391 species. The predominant phyla were Proteobacteria (36.92%), Firmicutes (34.21%), and Bacteroidetes (12.97%). The most prevalent families were Streptococcaceae, Helicobacteraceae, Prevotellaceae, and Pasteurellaceae. At the genus level, Streptococcus (21.71%), Helicobacter (18.39%), and Prevotella (9.99%) accounted for nearly half of the total relative abundance. Alpha diversity indices indicated moderate richness and evenness across samples. Conclusions: The gastric antrum microbiome of H. pylori-negative Greek individuals exhibits substantial taxonomic diversity dominated by Proteobacteria and Firmicutes. The microbial community structure aligns closely with profiles reported in other global populations. These findings provide a reference baseline for future comparative analyses involving H. pylori-positive individuals to better understand microbiome shifts associated with colonization and gastric disease. Full article

(This article belongs to the Special Issue Next-Gen Sequencing Advances Pathogen Research in Health, Agriculture & Environment)

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14 pages, 678 KB

Open AccessArticle

Glnk Mediates Carbapenem Resistance Through the NtrB/NtrC-OprD Regulatory Pathway in Pseudomonas aeruginosa

by Xiaomeng Sun, Yiming Li, Xuetao Gong, Qitong Du, Yongxin Jin, Zhihui Cheng, Shouguang Jin and Weihui Wu

Pathogens 2026, 15(3), 289; https://doi.org/10.3390/pathogens15030289 - 6 Mar 2026

Abstract

Pseudomonas aeruginosa is a major causative agent of nosocomial infections worldwide. Carbapenems are the first-line agents for combating severe P. aeruginosa infections. However, the increasing prevalence of carbapenem-resistant P. aeruginosa (CRPA) has developed as a critical threat to global healthcare systems. In this [...] Read more.

Pseudomonas aeruginosa is a major causative agent of nosocomial infections worldwide. Carbapenems are the first-line agents for combating severe P. aeruginosa infections. However, the increasing prevalence of carbapenem-resistant P. aeruginosa (CRPA) has developed as a critical threat to global healthcare systems. In this study, we demonstrated that a mutation in the core nitrogen metabolism regulatory gene glnK decreases carbapenem resistance in P. aeruginosa. OprD, the major porin for carbapenem uptake, is upregulated in the glnK mutant, resulting in decreased resistance. We further found that the NtrB/NtrC two-component regulatory system is upregulated in the glnK mutant. An electrophoretic mobility shift assay (EMSA) and genetic studies revealed a direct regulatory role of NtrC on the expression of oprD. Deletion of ntrB, ntrC, or oprD in the glnK mutant restored the bacterial resistance to carbapenems. These results reveal that a GlnK-NtrB/NtrC-OprD regulatory pathway affects carbapenem resistance, shedding light on the regulatory relationship between nitrogen metabolism and carbapenem resistance in P. aeruginosa. Full article

(This article belongs to the Special Issue Pathogenesis, Antibiotic Resistance, and Host Immune Responses to Bacterial Infections)

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23 pages, 4157 KB

Open AccessReview

Antimicrobial Resistance: A Bibliometric Review of Patient Health, Mechanisms, and Therapeutic Strategies

by Peter E. Murray, Jonathan A. Coffman and Franklin Garciá-Godoy

Pathogens 2026, 15(3), 288; https://doi.org/10.3390/pathogens15030288 - 6 Mar 2026

Abstract

Antimicrobial resistance is a growing global health crisis, with projections estimating up to 10 million deaths annually and more than 130 million hospitalizations attributable to resistant infections. Resistance emerges through microbial adaptation to sustained antimicrobial pressure, resulting in genetic and phenotypic mechanisms such [...] Read more.

Antimicrobial resistance is a growing global health crisis, with projections estimating up to 10 million deaths annually and more than 130 million hospitalizations attributable to resistant infections. Resistance emerges through microbial adaptation to sustained antimicrobial pressure, resulting in genetic and phenotypic mechanisms such as target mutations, enzymatic drug inactivation, efflux pump activation, biofilm formation, and metabolic adaptation that drive the emergence of multidrug-resistant pathogens and limit effective therapy. This bibliometric review analyzes the MEDLINE-indexed articles to characterize patient health and age factors, resistance mechanisms, pathogen types, and therapeutic strategies associated with antimicrobial resistance. The findings demonstrate that antimicrobial resistance is disproportionately reported among adults and chemotherapy-treated patients, with transmitted resistance emerging as the dominant driver, emerging from antibiotic misuse or overuse. Despite extensive mechanistic knowledge, treatment remains largely focused on escalation to newer antibiotics, while combination and adjunctive therapies are less commonly reported. These results analyze 308,290 studies to identify patient-related contexts, resistance mechanisms, pathogens, and therapeutic strategies. Full article

(This article belongs to the Section Bacterial Pathogens)

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26 pages, 2992 KB

Open AccessArticle

Native Bacillus-Based Probiotic Consortia Suppress Vibrio parahaemolyticus and Restructure Hatchery Water Microbiomes in Shrimp Larval Systems

by Betty Pazmiño-Gomez, Karen Rodas-Pazmiño, Rodrigo Pazmiño-Pérez, Tania Tapia-Guijarro, Wilman Balcazar-Quimi, Samuel Valle-Asan, Salma Salazar-Vera, Martin Villalva-Vera, Deily Ochoa-Fajardo and Edgar Rodas-Neira

Pathogens 2026, 15(3), 287; https://doi.org/10.3390/pathogens15030287 - 6 Mar 2026

Abstract

Shrimp aquaculture is constrained by opportunistic bacterial pathogens, particularly Vibrio parahaemolyticus, whose proliferation in hatchery systems is shaped by microbial community structure. We evaluated the antagonistic activity and microbiome effects of two native Bacillus-based probiotic consortia (CN5, RS3) applied alone or [...] Read more.

Shrimp aquaculture is constrained by opportunistic bacterial pathogens, particularly Vibrio parahaemolyticus, whose proliferation in hatchery systems is shaped by microbial community structure. We evaluated the antagonistic activity and microbiome effects of two native Bacillus-based probiotic consortia (CN5, RS3) applied alone or combined (MIX) in shrimp larval culture water over 30 days, relative to a no-probiotic control. Treatments were assessed using standardized in vitro inhibition assays, 16S rRNA gene (V3–V4) amplicon sequencing, functional inference, and integrative multivariate and structural modeling. All probiotic treatments showed consistently high antagonistic activity against V. parahaemolyticus, whereas the control showed no inhibition. Amplicon profiling indicated treatment-associated microbiome restructuring, with increased Bacillus dominance and reduced relative abundance of Vibrio spp. under probiotic conditions. Multivariate analyses separated probiotic and control groups, and PLS-SEM identified Bacillus dominance as a central driver of antagonistic activity mediated by inferred bioactive functional potential, while water-quality variables had limited direct effects. Probiotics were administered directly to the culture water once daily after routine water exchange to 1 × 10⁶ CFU mL⁻¹ (CN5 or RS3); MIX was applied 1:1 (v/v) at the same total dose. Full article

(This article belongs to the Special Issue One Health Perspectives on Foodborne Pathogens: Evolution, Resistance, and Prevention)

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12 pages, 869 KB

Open AccessArticle

Carcass-Based Surveillance of Amphibian Herpesviruses, Ranaviruses and Batrachochytrium dendrobatidis in Schleswig-Holstein, Northern Germany

by Natalie Steiner, Lotte C. Striewe, Christoph Leineweber, Sara Grau Camps, Peter Wohlsein, Frederik Elze, Simon Rohner, Rachel E. Marschang and Ursula Siebert

Pathogens 2026, 15(3), 286; https://doi.org/10.3390/pathogens15030286 - 6 Mar 2026

Abstract

Amphibian populations are undergoing dramatic global declines, with infectious diseases recognized as major contributors. While chytridiomycosis, caused by Batrachochytrium dendrobatidis (Bd), and disease caused by ranaviruses are well known, herpesviruses in amphibians remain comparatively neglected. We conducted a passive survey using [...] Read more.

Amphibian populations are undergoing dramatic global declines, with infectious diseases recognized as major contributors. While chytridiomycosis, caused by Batrachochytrium dendrobatidis (Bd), and disease caused by ranaviruses are well known, herpesviruses in amphibians remain comparatively neglected. We conducted a passive survey using carcasses collected between 2022 and 2025 in Schleswig-Holstein, northern Germany. Dead amphibians (n = 187) were dissected. Skin, kidney, liver, and brain samples were screened for Bd, ranaviruses, bufonid herpesvirus 1 (BfHV1), and ranid herpesvirus 3 (RaHV3) by PCR. BfHV1 was detected in nearly half of the Bufo bufo (common toads; 48.6%), while RaHV3 was identified in 23.6% of the Rana temporaria (common frogs) examined. Bd was detected in a single B. bufo, while ranaviruses were not detected. BfHV1 was present in skin, liver, kidney, and brain samples, whereas RaHV3 was detected exclusively in skin samples. No macroscopical or histological lesions characteristic of herpesviruses or Bd were found. However, the carcass-based approach frequently limited detailed examination due to compromised sample quality. Our findings confirm the presence of amphibian herpesviruses (BfHV1 and RaHV3) in the region without associated lesions, raising questions about their potential to cause systemic infections. Furthermore, our results highlight the limitations of carcass-based surveillance and underscore the need for complementary diagnostic approaches, such as immunohistochemistry and meta-omics. Full article

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12 pages, 264 KB

Open AccessReview

Acute Respiratory Infections in Ghanaian Children: Epidemiology, Antimicrobial Resistance, and Prevention Strategies

by Sabastine Eugene Arthur, Jessica Eyeson, Aaron Appiah Kubi, Faustina Amarteley Amartey, Raymond Matey, James Odame Aboagye and George Boateng Kyei

Pathogens 2026, 15(3), 285; https://doi.org/10.3390/pathogens15030285 - 6 Mar 2026

Abstract

Acute respiratory infections (ARIs) remain a common cause of morbidity and mortality in children, especially in sub-Saharan Africa, where countries such as Ghana are severely affected. This review presents recent data on ARI etiology, clinical burden, and antimicrobial resistance (AMR) from Ghana, spanning [...] Read more.

Acute respiratory infections (ARIs) remain a common cause of morbidity and mortality in children, especially in sub-Saharan Africa, where countries such as Ghana are severely affected. This review presents recent data on ARI etiology, clinical burden, and antimicrobial resistance (AMR) from Ghana, spanning the pre-COVID-19 era (2010–2019) to the post-pandemic period (2020–2025). Before the COVID-19 pandemic, viral infections, such as respiratory syncytial virus (RSV), rhinoviruses, and influenza viruses, were the major contributors, along with established bacterial pathogens such as Streptococcus pneumoniae and Haemophilus influenzae. Social determinants, including undernutrition and indoor air pollution, also influenced these infections. In the COVID era, we have seen dramatic shifts in pathogen seasonality, the scaling of oxygen delivery systems, and the implementation of genomic surveillance for SARS-CoV-2, as well as new features such as maternal RSV vaccination and monoclonal antibody therapy. Despite its successes in vaccination coverage and health system strengthening, some challenges remain, including fluctuations in implementation and surveillance issues. The simultaneous challenges of pneumonia and hygiene will require integrated, coordinated, multisectoral responses that incorporate surveillance with antibiotic stewardship, sustainable oxygen systems, and interventions for nutrition and environmental health. The review also highlights research priorities and makes policy recommendations well aligned to support national ARI control efforts aimed at reducing child mortality due to ARI and achieving Sustainable Development Goals targets on child health. Full article

12 pages, 2517 KB

Open AccessReview

Astrocytoma in Patients with HIV—Review of the Literature and Case Report

by Florentina Dumitrescu, Eugenia-Andreea Marcu, Vlad Pădureanu, Cristiana-Luiza Rădoi-Troacă, Rodica Pădureanu and Lucian Giubelan

Pathogens 2026, 15(3), 284; https://doi.org/10.3390/pathogens15030284 - 5 Mar 2026

Abstract

Astrocytomas are among the most common primary tumors of the central nervous system, arising from astrocytic glial cells and encompassing a wide spectrum of histopathological grades and clinical behaviors. Human immunodeficiency virus (HIV) infection is characterized by chronic immune dysregulation, neuroinflammation, and increased [...] Read more.

Astrocytomas are among the most common primary tumors of the central nervous system, arising from astrocytic glial cells and encompassing a wide spectrum of histopathological grades and clinical behaviors. Human immunodeficiency virus (HIV) infection is characterized by chronic immune dysregulation, neuroinflammation, and increased susceptibility to both opportunistic infections and malignancies. The management of astrocytomas in patients living with HIV presents unique clinical challenges but should, whenever feasible, follow standard neuro-oncological principles. We report the case of a 34-year-old man with well-controlled HIV infection who presented in February 2025 with progressive neurological symptoms. Brain imaging revealed a left temporo-insular lesion, and the diagnosis was confirmed by neuronavigation-guided biopsy performed on 31 March 2025. Histopathological and immunohistochemical evaluation established the diagnosis of an isocitrate dehydrogenase (IDH) wild-type astrocytoma, central nervous system (CNS) World Health Organization (WHO) grade 2, according to the 2021 classification of central nervous system tumors. Full article

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7 pages, 406 KB

Open AccessBrief Report

Serum Cytokines and TGF-β1: A Window into Syphilis Among People Living with HIV

by Adriana Hernández-Pliego, Santa García-Cisneros, Dayana Nicte Vergara-Ortega, Fernando R. Esquivel-Guadarrama, Antonia Herrera-Ortíz, Cairo Toledano-Jaimes and Miguel Angel Sánchez-Alemán

Pathogens 2026, 15(3), 283; https://doi.org/10.3390/pathogens15030283 - 5 Mar 2026

Abstract

Treponema pallidum is the etiological cause of syphilis, and in recent years, reemergence has been reported, especially among men who have sex with men and people living with HIV (PLWH). Certain cytokines may act as hallmark biomarkers in the progression of syphilis in [...] Read more.

Treponema pallidum is the etiological cause of syphilis, and in recent years, reemergence has been reported, especially among men who have sex with men and people living with HIV (PLWH). Certain cytokines may act as hallmark biomarkers in the progression of syphilis in PLWH, and studying how the immune system works against T. pallidum is important, especially in PLWH, whose immune system is compromised. We evaluated the serum expressions of IFN, TNF, IL-10, TGF-β1 and IL-17 in men living with HIV (MLWH) and their association with distinct stages of syphilis. We recruited MLWH from March to October 2022. A blood sample was requested, syphilis was detected using the reverse algorithm, and antibodies were titrated to determine the stage. Each of the cytokines studied was quantified using commercial ELISA kits. The following groups were formed: active syphilis (n = 217), cured syphilis (n = 134), and without syphilis (n = 159). The prevalence of elevated TGF-β1 differed between groups, being highest in individuals with active syphilis (51.6%; median 319 pg/mL), followed by those with cured syphilis (41.0%; median 137.0 pg/mL). Younger participants and persons without a history of sexually transmitted infections were more likely to present with high TGF-β1 levels. TGF-β1 may act as a biomarker in active syphilis and could suppress the inflammatory response against spirochetes. Full article

(This article belongs to the Special Issue Surveillance, Prevention and Control of Sexually Transmitted Infections)

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14 pages, 3742 KB

Open AccessArticle

Phenotypic and Transcriptomic Characterization of Host-Associated Responses in a Carbapenem-Resistant Klebsiella pneumoniae ST11 Clinical Isolate

by Miaomiao Hua, Jun Ji, Zhongyu Wang, Jingjing Li and Xiaoli Cao

Pathogens 2026, 15(3), 282; https://doi.org/10.3390/pathogens15030282 - 5 Mar 2026

Abstract

Carbapenem-resistant Klebsiella pneumoniae (CRKP) sequence type 11 (ST11) is widely reported in Asia and represents an important clinical concern. Although antimicrobial resistance in ST11 isolates has been extensively investigated, less is known about the phenotypic characteristics and host-associated transcriptional responses of individual clinical [...] Read more.

Carbapenem-resistant Klebsiella pneumoniae (CRKP) sequence type 11 (ST11) is widely reported in Asia and represents an important clinical concern. Although antimicrobial resistance in ST11 isolates has been extensively investigated, less is known about the phenotypic characteristics and host-associated transcriptional responses of individual clinical isolates. In this study, we performed an in-depth characterization of a clinical ST11 CRKP isolate, NJGLYY4165. Phenotypic assays were used to evaluate bacterial growth, biofilm formation, serum resistance, inflammatory responses, and virulence in a Galleria mellonella infection model. Whole-genome sequencing and bacterial transcriptomic profiling were conducted to examine gene expression changes at 4 h during interaction with human intestinal epithelial cells and macrophages. NJGLYY4165 exhibited increased survival following exposure to normal human serum in vitro but displayed reduced lethality in the Galleria mellonella infection model compared with selected reference strains. Infection of host cells induced marked inflammatory responses. Transcriptomic analysis revealed extensive gene expression remodeling at the examined time point during host interaction, including upregulation of central metabolic pathways and iron acquisition systems, particularly under macrophage-associated conditions. This study provides a detailed phenotypic and single-time-point transcriptomic description of host-associated responses in a clinical ST11 CRKP isolate. The observed metabolic and iron acquisition responses may contribute to adaptation under host-associated conditions; however, because comparative analyses with non-ST11 or non-epidemic strains were not included, it remains unclear whether these features are isolate-specific, ST11-associated, or represent general adaptive responses of K. pneumoniae. Further comparative and time-course studies across diverse clinical isolates will be required to clarify temporal dynamics and broader epidemiological relevance. Full article

(This article belongs to the Section Bacterial Pathogens)

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19 pages, 3142 KB

Open AccessArticle

Cattle Immunization with T7 Phage-Displayed Whole-Tick Antigens Reduces Amblyomma americanum Feeding Efficiency and Blocks Larval Tick Hatching

by Moiz Ashraf Ansari, Alex Kiarie Gaithuma, Thu-Thuy Nguyen, William Tae Heung Kim, Emily Bencosme-Cuevas, Jacquie Berry, Jennifer Fridley, Kimberly Lohmeyer, Marie-Eve Koziol and Albert Mulenga

Pathogens 2026, 15(3), 281; https://doi.org/10.3390/pathogens15030281 - 5 Mar 2026

Abstract

This study demonstrates the feasibility of using a T7 phage display platform to deliver a library of tick antigens as a vaccine to disrupt tick feeding in cattle. Cattle were vaccinated at three-week intervals via intradermal and intramuscular routes with a cocktail of [...] Read more.

This study demonstrates the feasibility of using a T7 phage display platform to deliver a library of tick antigens as a vaccine to disrupt tick feeding in cattle. Cattle were vaccinated at three-week intervals via intradermal and intramuscular routes with a cocktail of male and female Amblyomma americanum T7 phage display cDNA libraries, with and without adjuvant. ELISA and Western blot analyses confirmed that vaccinated cattle mounted immune responses directed against phage-displayed tick proteins rather than the T7 phage backbone. Vaccine-induced antibodies recognized both native tick salivary gland proteins and selected recombinant salivary proteins, indicating effective antigen presentation and biologically relevant immunity with binding to native tick saliva proteins. The adjuvanted formulation elicited significantly stronger immune responses than phage-only immunization. Immunized cattle exhibited robust immune memory, evidenced by a pronounced anamnestic response following tick infestation. This immunity translated into measurable anti-tick effects, including reduced tick feeding efficiency and blood ingestion. Tick reproductive success was severely compromised, with larval hatching declining from 54% in ticks fed on control cattle to 4% in ticks fed on immunized cattle. This study establishes a practical and scalable T7 phage-displayed whole-tick antigen platform capable of inducing durable anti-tick immunity in cattle. Full article

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22 pages, 1938 KB

Open AccessReview

Classification and Anti-Streptococcus mutans Mechanism Summary of Chinese Botanical Products

by Yuelin Li, Zhongyi Fang and Ruijie Huang

Pathogens 2026, 15(3), 280; https://doi.org/10.3390/pathogens15030280 - 4 Mar 2026

Abstract

Dental caries, one of the most prevalent diseases worldwide, poses a significant threat to oral health. Streptococcus mutans is one of the key pathogenic bacteria associated with dental caries. Numerous Chinese botanical products (CBPs) have been shown to possess antibacterial effects against S. [...] Read more.

Dental caries, one of the most prevalent diseases worldwide, poses a significant threat to oral health. Streptococcus mutans is one of the key pathogenic bacteria associated with dental caries. Numerous Chinese botanical products (CBPs) have been shown to possess antibacterial effects against S. mutans. However, given the wide variety of CBPs that have been investigated, a systematic summary of their effects is needed. To address this need, in the present review, CBPs are categorized into five groups based on their major bioactive components: organic acid-based CBPs, alkaloid-based CBPs, phenol-based CBPs, anthraquinone-based CBPs, and other types. In addition to their chemical composition, the conventional use, pharmacological effects, and toxicity of these CBPs are also discussed, followed by an exploration of their anti-S. mutans mechanisms, including the synthesis of biofilm scaffolds and water-insoluble glucans, energy metabolism and soluble glucan production, acid generation and tolerance, bacterial cell integrity, remineralization processes, and intercellular communication via quorum sensing (QS). In summary, it is suggested that CBPs have considerable benefits in caries prevention and could be promisingly applied in clinical treatments. Full article

(This article belongs to the Section Bacterial Pathogens)

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11 pages, 3713 KB

Open AccessCase Report

Feline Cryptococcosis: Two Case Reports and a Literature Review

by Stanisław Dzimira

Pathogens 2026, 15(3), 279; https://doi.org/10.3390/pathogens15030279 - 4 Mar 2026

Abstract

Cryptococcosis is a severe systemic mycosis affecting humans and animals, caused primarily by members of the Cryptococcus neoformans/Cryptococcus gattii species complex. In cats, it is the most common systemic fungal infection and may present with non-specific signs involving the upper respiratory [...] Read more.

Cryptococcosis is a severe systemic mycosis affecting humans and animals, caused primarily by members of the Cryptococcus neoformans/Cryptococcus gattii species complex. In cats, it is the most common systemic fungal infection and may present with non-specific signs involving the upper respiratory tract, skin, lymph nodes, eyes, or the central nervous system. This study presents two feline cases of cryptococcosis diagnosed by cytological examination and provides an updated literature review. Fine-needle aspiration biopsies were performed in two cats with chronic nasal swelling and submandibular enlargement. Cytological smears stained with hematoxylin and eosin revealed spherical to oval yeast-like organisms with a characteristic thick, non-staining capsule, narrow-based budding, and absence of pseudohyphae, consistent with Cryptococcus spp. Based on cytological findings, both patients were treated with oral itraconazole, resulting in favorable clinical outcomes. A limitation of this study is the lack of mycological culture or molecular confirmation, owing to the owners’ refusal of further diagnostic testing. These cases highlight the diagnostic value of cytology as a rapid tool for differentiating fungal infections from neoplastic processes. Early diagnosis and antifungal therapy are crucial for successful management. From a One Health perspective, feline cryptococcosis may indicate shared environmental exposure risks relevant to both animal and human health. Full article

(This article belongs to the Section Fungal Pathogens)

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20 pages, 943 KB

Open AccessReview

Elizabethkingia Species as an Emerging Pathogen: A Comprehensive Review of Clinical and Microbiological Evidence

by Jacqueline Wan Yu Tan, Bernice Jia Xin Lian, Cheryl Ying Xuan Loh and Kay Choong See

Pathogens 2026, 15(3), 278; https://doi.org/10.3390/pathogens15030278 - 4 Mar 2026

Abstract

Elizabethkingia species are rare but increasingly recognised Gram-negative pathogens linked to healthcare-associated transmission, intrinsic multidrug resistance, and severe infection in vulnerable hosts. We performed a comprehensive review of human Elizabethkingia infections by systematically searching PubMed on 18 October 2025 and included English-language case [...] Read more.

Elizabethkingia species are rare but increasingly recognised Gram-negative pathogens linked to healthcare-associated transmission, intrinsic multidrug resistance, and severe infection in vulnerable hosts. We performed a comprehensive review of human Elizabethkingia infections by systematically searching PubMed on 18 October 2025 and included English-language case reports, case series, and outbreak investigations; species were analysed as reported (legacy nomenclature retained), and adults were defined as ≥18 years. In total, 374 studies were included (300 case reports, 41 case series, 33 outbreak investigations). Adult infections were predominantly healthcare-related, affected older adults with substantial comorbidities and most often presented as bacteraemia or sepsis and pneumonia; crude mortality in adult case reports was 32.8%. Paediatric disease was concentrated in neonates and Neonatal Intensive Care Unit (NICU) settings, with meningitis and bloodstream infection predominating; crude mortality in paediatric case reports was 23.3%, and neurological sequelae were frequently reported among survivors. Across studies, isolates showed broad resistance to β-lactams and near-universal resistance to carbapenems, with variable activity to fluoroquinolones and trimethoprim–sulfamethoxazole and more consistent in vitro activity to minocycline. Species misidentification (notably Elizabethkingia anophelis as Elizabethkingia meningoseptica) and heterogeneous susceptibility testing limited comparability. Outbreak investigations repeatedly implicated water-associated reservoirs and reusable equipment, underscoring the need for improved diagnostics, susceptibility-guided therapy and water-focused infection prevention. Full article

(This article belongs to the Special Issue Diagnosis, Immunopathogenesis and Control of Bacterial Infections)

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