BACKGROUND:Colonization of Group B Streptococcus (GBS) in pregnant women represents a primary risk factor for neonatal infections and preterm stillbirth, highlighting the necessity for pre-delivery detection. Traditional culture methods and standard molecular assays are limited, highlighting the demand for a rapid, efficient, and straightforward GBS detection technique. This study focused on developing and validating an in-house rapid assay utilizing the CRISPR/Cas12a system, augmented with recombinase polymerase amplification (RPA). METHOD:A rapid, sensitive, and specific GBS detection platform was established, employing CRISPR/Cas12a in conjunction with isothermal RPA. Specificity assessments were conducted against GBS as well as other prevalent pathogens of the female reproductive tract. The limit of detection was determined using gradient-diluted GBS-originated plasmids, while clinical swabs from pregnant women were used to evaluate diagnostic efficacy against a commercial quantitative real-time PCR (qPCR) assay. RESULT:The GBS rapid assay demonstrated high efficiency, completing the test within one hour, with results available for interpretation through visual examination or a fluorescence reader. This method accurately differentiated GBS from non-target control pathogens, achieving a detection limit of 201.64 copies/µl with a 95% Confidence Interval (95% CI): 66.90-607.75, as assessed by colloidal gold test strips. In a clinical performance evaluation involving 1000 vaginal-rectal swabs from pregnant women, the rapid assay results correlated closely with those from the conventional qPCR method. CONCLUSION:An easy-to-operate GBS assay, featuring a short turnaround time, was developed and validated with high sensitivity, specificity, and accuracy, indicating significant potential for clinical application.
BACKGROUND:Recently a Corynebacterium diphtheriae (C. diphtheriae) outbreak was reported in Europe described as the largest upsurge of cases in the last 70 years. Clinically relevant infections and transmission events are not necessarily associated only with toxigenic strains, but they can also be caused by non-toxigenic diphtheria toxin gene-bearing (NTTB) C. diphtheriae. PCR-based identification of potentially toxigenic strains needs to be complemented by testing for diphtheria toxin (DT) production, which is why diagnosis is notoriously difficult. METHODS/FINDINGS:C. diphtheriae was cultivated from an intraoperative swab. The strain although PCR positive for tox gene, lacked DT expression in Elek test and was thus categorized as non-toxigenic tox-bearing (NTTB). Short- and long-read whole-genome sequencing (WGS) revealed a truncated tox gene. At nucleotide position 19, the insertion sequence IS1132 was inserted in the reverse direction. The isolate had a novel sequence type, ST-1111, and core genome MLST (cgST-3956 in BIGSdb-Pasteur's nomenclature) showed it is not related to any of the previously described C. diphtheriae outbreak strains in Germany. INTERPRETATION:Here we report a novel ST of NTTB C. diphtheriae with interruption of its tox gene by IS1132 at nucleotide position 19. Our findings highlight the value of WGS for resolving potentially toxin-positive cases and for reliably assessing the clinical risk and epidemiological context, which are the key prerequisites for infection control measures and public health responses.
Onychomycosis caused by non-dermatophyte molds (NDMs) is rare, and Chaetomium spp. represents an extremely rare pathogen with fewer than 20 cases reported worldwide. Misdiagnosis frequently leads to treatment failure and relapse. We report the first documented case of Chaetomium spp. onychomycosis from Indonesia: a 29-year-old immunocompetent woman with nail trauma and frequent swimming who presented with dystrophic changes and brownish-black discoloration of multiple toenails and one fingernail. Identification was made by direct microscopy and SDA culture. Antifungal susceptibility testing revealed resistance to itraconazole and ketoconazole, with sensitivity to terbinafine and fluconazole. The patient received a three-month course of topical terbinafine cream (twice daily), 10% salicylic acid, and oral fluconazole (150 mg, increased to 300 mg once weekly). Complete remission was achieved with no recurrence at three months post-treatment. This case, supported by a literature review, underscores the need to consider rare NDM pathogens in refractory nail infections and the critical role of antifungal susceptibility testing in guiding combination therapy.
The CpxRA two-component system is a key regulator of envelope stress responses in Gram-negative bacteria. In this study, a gain-of-function mutant in Pseudomonas aeruginosa was generated by truncating the periplasmic sensing domain (PSD) of the sensor kinase CpxS in PAO1 (PAO1::cpxSΔ32-147), leading to constitutive activation of its cognate response regulator CpxR. The mutant exhibited a 2- to 4-fold increase in antimicrobial resistance while showing significantly attenuated virulence traits: swimming and swarming motility decreased by 44% and 34%, respectively, and production of pyoverdine, rhamnolipids, pyocyanin, and biofilm was reduced by 1.8-, 6.7-, 1.9-, and 3.5-fold compared to the wild-type PAO1. Cellular virulence was also impaired. The mutant exhibited significantly reduced cytotoxicity toward A549 lung epithelial cells, with the relative inhibition rate decreasing from 79.6% to 25.4% at multiplicities of infection (MOI) 100. Additionally, its intracellular replication in MH-S macrophages was reduced by 85%. In a murine acute pneumonia model, infection with PAO1::cpxSΔ32-147 resulted in only 10% lethality at 72 h, contrasting with 100% for PAO1. This attenuation correlated with lower lung bacterial burdens, reduced levels of inflammatory cytokines (TNF-α, IL-6) in bronchoalveolar lavage fluid, decreased oxidative damage, and higher antioxidant enzyme activity. All observed phenotypes were strictly CpxR-dependent. Transcriptomic analysis further revealed coordinated downregulation of genes associated with secretion systems, iron acquisition, and quorum sensing, indicating multi-pathway repression of virulence. Collectively, this study identifies the CpxRS system as a central regulator of pathogenicity in P. aeruginosa and supports its therapeutic potential as an anti-virulence target in multidrug-resistant infections.
Rapid diagnosis of TB infections and effective drug treatment is central to reducing disease morbidity and mortality. Here we evaluate the performance of TBseek, a multiplex targeted PCR nanopore sequencing-based test designed for TB identification and antibiotic resistance genotyping. From the analysis of 185 clinical samples, TBseek test demonstrated significantly superior diagnostic performance compared to Xpert PCR test, fluorescent microscopy and culture, achieving a sensitivity of 89.47%, specificity of 96.97%, and an AUC of 0.93. Retrospective analysis of 136 TBseek-positive specimens showed rapid detection: 78.68% met the ≥ 10 MTB-specific reads threshold within 1 h, 91.18% by 3 h, and 100% by 8 h. In 43 MTB-positive samples, full-length gene primers consistently yielded a higher proportion of MTB sequences compared to hotspot-targeted primers, demonstrating strong specificity. Compared to phenotypic drug sensitivity testing results for 76 TB positive culture samples, TBseek had high detection sensitivities for resistance to rifampicin (100.00%), isoniazid (83.33%), ethambutol (100.00%), streptomycin (95.24%) and levofloxacin (90%). Based on these findings, TBseek delivered high performance for detection of TB and antibiotic resistance. With further validation, TBseek has clinical potential as a first-tier screen to evaluate suspected TB cases and for guiding and monitoring personalized treatments.
Coronavirus disease caused by the SARS-CoV-2 has become one of the most significant global health challenges. The coinfections in patients with COVID-19 are considered an important risk factor. The Instituto Nacional de Enfermedades Respiratorias (INER) was the main COVID-19 reference centre in Mexico and reported the first patient infected with SARS-CoV-2 coinfected with A. baumannii. A total of 179 Acinetobacter spp. clinical isolates were collected during pandemic period with the goal of determining the genetic (screening to carbapenemases and PFGE analysis) and antimicrobial resistance profile. In addition, biofilm formation and genomic analysis were performed. We observed that coinfections were caused by distinct A. baumannii clones, and most of them exhibited a multidrug-resistant phenotype primarily associated with the blaOXA-23 gene (76.4%). A subset of A. baumannii isolates were sequenced and subjected to genome analyses. We identified that the predominant sequence types were ST2057/ST473 (60%) and ST1837/ST367 (36.6%). The phylogenetic analysis showed that the population structured followed a ST clustering and did not follow a dispersion according to the collection year, virulome, resistome or if it was isolated from a COVID-19 or non-COVID-19 patient. Similarly, when comparing the genome content between A. baumannii from COVID-19 or non-COVID-19 patients no distinction was observed in its accessory genome suggesting that A. baumannii does not require a specific array of genes to coinfect patients; any strain circulating in the hospital environment can cause outbreaks, particularly in patients undergoing invasive procedures like mechanical ventilation. The outbreak control measures effectively contained A. baumannii at the main COVID-19 concentration centre. This study highlights the importance of monitoring opportunistic pathogens like A. baumannii during global health emergencies.
Cytolethal distending toxin (CDT), a cyclomodulin and genotoxin produced by many Gram-negative bacteria including pathogenic Escherichia coli, disrupts the eukaryotic host cell cycle to facilitate bacterial colonization. In a survey of dairy cows in Hungary, 7 % of of sampled animal and farm environment isolates carried CDT-producing E. coli (CTEC). Whole genome sequencing (WGS) performed on six recent isolates and three historical CTEC strains revealed association with diverse pathotypes, including enteropathogenic- (EPEC) and necrotoxigenic- (NTEC) types, as well as several unclassified atypical strains. Four of the six strains isolated in this study carried plasmid encoding cdt-III+ NTEC, while a prophage based cdt-V allele was present in the remaining two strains which were of unknown pathotype. These isolates exhibited significant variability in their supplementary virulence genes (SVGs) content as well as in multiple prophage regions linked to virulence or fitness factors. They were phylogenetically distinct and comprised of only distantly related sequence types (STs) that include two novel STs. Several isolates also carried other genotoxic cyclomodulins such as the cytotoxic necrotizing factor (cnf), the cycle inhibiting factor (cif), and colibactin (polyketide synthase, pks) which is located on a genomic island, indicating multiple mechanisms for dysplastic damage of the eukaryotic host cells exist and highlight the role of horizontal gene transfer in the zoonotic and pathogenic potential of CTEC.
Herpes simplex virus 1 (HSV-1) is a member of alphaherpesvirus that can cause some important human diseases, and type I interferon (IFN-I)-mediated antiviral effect plays a vital role in the innate immune response, whereas this reaction can be negatively regulated by some HSV-1 encoded proteins. However, it remains unknown whether additional HSV-1 factors contribute to this process. Here, we found that the HSV-1 encoded uracil-DNA glycosylase, UL2, can inhibit Sendai virus (SeV)-induced IFN-β activity. Mechanically, UL2 interacts with the components of RIG-I-like receptor (RLR) signaling pathway, including TBK1 and activated IRF3. While UL2 does not affect the ubiquitination of TBK1 or IRF3, it rather hinders the SeV-stimulated phosphorylation of IRF3 at Ser396. Simultaneously, UL2 blocks the formation of IRF3 dimer and its nuclear translocation. Therefore, these results suggested a crucial connection between UL2 and IFN-β signaling pathway, which may take considerable role in the HSV-1 evasion of the host antiviral response.
BACKGROUND:Respiratory syncytial virus (RSV) poses a significant global health burden, especially among young children. Whole-genome sequencing (WGS) is key for tracking RSV evolution and epidemiology, underscoring the importance of establishing efficient workflows for routine surveillance. OBJECTIVES:To optimize a streamlined, one-step, multiplex RT-PCR method for RSV WGS, enabling precise genetic characterization of circulating RSV viruses across Portugal. STUDY DESIGN:A one-step RT-PCR protocol was adapted from a published method and used to characterize RSV-positive samples collected by the National RSV Surveillance Network (VigiRSV) from 2021 to 2024. Of the 1167 samples received, those with real-time PCR cycle threshold values below 25 were considered eligible for sequencing. From this subset, 166 samples were randomly selected for assay development and validation, ensuring proportional geographic and seasonal representation. RESULTS:From the 166 samples tested, genome completeness averaged 92.69% (95% CI: 90.15%-95.23%), with an interquartile range of 6.60%, reflecting a generally consistent sequencing performance. This resulted in 134 near-complete genomes (≥30 × depth of coverage across ≥90% of the reference genome). Phylogenetic analysis revealed the circulation of 13 RSV A lineages and three RSV B lineages across Portugal over the study period. CONCLUSIONS:This adapted protocol achieved high overall horizontal coverage with consistent performance across seasons and regions, demonstrating its reliability for RSV whole-genome sequencing. The strong performance observed over multiple seasons and geographic regions indicates that the method is reproducible and suitable for integration into routine surveillance workflows. These characteristics make it a practical and scalable tool for enhancing RSV epidemiology and public health monitoring.
Extraintestinal pathogenic Escherichia coli (ExPEC) causing bloodstream infections encompass diverse evolutionary lineages with distinct genomic and pathogenic traits. Here, we applied an integrative strategy combining population-level analysis of type II toxin-antitoxin (TA) systems, comparative genomics, and phenotypic assays to explore ExPEC diversity. Screening of 85 ExPEC bloodstream isolates revealed phylogroup-associated TA distribution patterns, with phylogroups A and B1 exhibiting more complex and heterogeneous TA repertoires. These signatures guided the selection of two representative strains of the general TA distribution pattern, Ec182 (phylogroup A) and Ec272 (phylogroup B1), for detailed genomic and phenotypic investigation. Whole-genome sequencing demonstrated that differences in TA repertoires are embedded within broader phylogenetic and genomic contexts, including variation in virulence-associated genes and genome organization. Phenotypic analyses revealed distinct pathogenic behaviors between the two strains, mirroring their divergent genomic architectures. While direct causal links between specific TA systems and phenotypic traits were not established, the concordance between phylogroup, TA system composition, and pathogenic profiles highlights distinct adaptive strategies among ExPEC lineages. Overall, our results indicate that ExPEC bloodstream isolates comprise a spectrum of phylogroup-dependent evolutionary and pathogenic strategies. This integrative framework underscores the importance of considering evolutionary background when interpreting virulence-associated features in ExPEC.
INTRODUCTION:Aspergillus fumigatus causes life-threatening infections in immunocompromised individuals. Neutrophils are essential for antifungal defence, but their function is often impaired in these patients. Granulocyte colony-stimulating factor (G-CSF) supports neutrophil survival and activation, yet systemic use can induce unwanted inflammation. The molecular mechanisms by which G-CSF enhances neutrophil function remain incompletely defined. OBJECTIVES:To investigate whether ex vivo G-CSF-activated neutrophil transfer improves outcomes in invasive A. fumigatus infection and to explore the potential involvement of INHBA in regulating neutrophil dysfunction. METHODS:Immunosuppressed mice were intranasally infected with A. fumigatus and subsequently received intravenous administration of G-CSF-activated neutrophils. Fungal burden, pulmonary inflammation, and cytokine expression were assessed. Transcriptomic and single-cell RNA sequencing analyses identified pathways regulated by G-CSF and INHBA. In vitro assays examined the impact of recombinant INHBA on neutrophil functions. RESULTS:Transfer of G-CSF-activated neutrophils significantly improved survival, reduced fungal load, and decreased lung inflammation. G-CSF downregulated INHBA, while patient neutrophils displayed elevated INHBA expression. Functional studies showed INHBA suppressed neutrophil chemotaxis, phagocytosis, and NET formation. CONCLUSION:G-CSF enhances neutrophil antifungal activity and is associated with modulation INHBA, suggesting a potential regulatory axis in neutrophil dysfunction during A. fumigatus infection. Ex vivo G-CSF-activated neutrophil transfer may represent a promising immunotherapeutic strategy for invasive aspergillosis.
Rocky Mountain spotted fever (RMSF) is an important and potentially fatal tick-borne disease impacting people and dogs. RMSF, caused by Rickettsia rickettsii, is frequently reported in parts of the North, Central and South American countries. The treatment for RMSF is limited to tetracyclines, specifically to doxycycline. If untreated, the disease can progress rapidly to fatal outcomes, particularly in children. In recent years, fatality rates ranging from 30% to 80% have been reported throughout South America, Mexico, and in parts of Indian reservations in southwest regions of the USA. To aid in support of monitoring in vivo R. rickettsii infections, we developed a novel quantitative PCR (qPCR) assay to facilitate the sensitive and specific detection of R. rickettsii. The assay was designed and optimized using the surface cell antigen 4 gene as the target. The utility of the assay was defined for its specificity, analytical sensitivity, efficiency, and to monitor infections in the canine host following R. rickettsii infection challenges. With having high specificity and analytical sensitivity, the qPCR assay can be utilized for diverse research applications promoting investigations on R. rickettsii.
BACKGROUND:Mycoplasma pneumoniae (MP) is a common cause of community-acquired respiratory infections in children, with manifestations ranging from mild upper respiratory tract illnesses to pneumonia. Mycoplasma pneumoniae pneumonia (MPP) represents a more severe form of infection that often necessitates medical intervention. In children diagnosed with MPP, antimicrobial agents active against MP are indicated, and macrolide antibiotics represent the first-line therapy. However, macrolide-resistant MP (MRMP) strains have emerged worldwide, with a notable upward trend in both MP infection incidence and resistance rates, particularly in East Asia. This study aimed to investigate the prevalence of MP infection and the emergence of macrolide resistance in children during a period of elevated incidence, as well as to explore the underlying factors contributing to severe MPP (SMPP) among children in Guangzhou City. METHODS:The study enrolled a total of 10328 children suspected of having MP infection from November 2023 to December 2024. Respiratory tract specimens were collected from the study subjects and then analyzed using real-time polymerase chain reaction (PCR) to detect MP DNA and mutations associated with macrolide resistance at positions A2063G or A2064G. Moreover, demographic data and information on co-infecting common respiratory pathogens were collected during this analysis, and the risk factors for SMPP were analyzed. RESULTS:The positive detection rate of MP was 25.8%, and it decreased from 30.3% in the fourth quarter of 2023 (Q4 2023) to 10.1% in the fourth quarter of 2024 (Q4 2024). The highest positive rate of MP detection was among children aged 5-9 years, followed by those aged 10-14 years and 1-4 years. The detection rate of MRMP in MP-positive cases was 49.4%, and it rose from 37.8% in Q4 2023 to 61.9% in Q4 2024. Among the 1905 pneumonia inpatients who tested positive for MP, 7.4% (141/1905) were found to have co-infection with other common respiratory pathogens. The most prevalent co-infecting pathogens were human rhinovirus (RHV), human adenovirus (HADV), and influenza A virus (IAV). Detection of MRMP (OR = 1.833, 95% CI: 1.189-2.824, p = 0.006), presence of co-infection (OR = 2.209, 95% CI: 1.111-4.391, p = 0.024), and existence of comorbidities (OR = 4.431, 95% CI: 1.833-10.715, p = 0.001) were associated with an increased risk of SMPP. CONCLUSIONS:We reported that during the epidemic period of MP in children, the MRMP positive rate remained persistently high across all age groups in a cohort comprising both outpatients and inpatients. Among hospitalized children with MPP, those with MRMP detection, co-infection with other respiratory pathogens, or underlying comorbidities were more likely to develop severe conditions. These findings suggest that monitoring MRMP in children at potential high risk, particularly those who requiring hospitalization, may be essential for the development of effective prevention and treatment strategies.
Multidrug-resistant Mycobacterium tuberculosis complex (MTBC) remains a major global health challenge, yet the drug-specific evolutionary pathways through which resistance accumulates are not fully understood. Heterogeneous minor resistant variants (hSNPs) and compensatory mutations are increasingly recognized as important drivers of the emergence, stability, and transmission of drug-resistant strains. We analyzed 143 clinical MTBC isolates using whole-genome sequencing combined with phenotypic drug susceptibility testing to characterize lineage distribution, resistance-associated mutations, hSNPs, compensatory adaptations, and genomic clustering. We performed evolutionary accumulation modelling with HyperTraPS to infer the most probable order of resistance acquisition. Compensatory mutations in rpoA, rpoC, or the non-RRDR region of rpoB were detected in 73.1% of genotypic rifampicin-resistant isolates, with the rpoB p.Ser450Leu mutation showing the highest frequency of compensatory adaptation (92.2%). Drug-specific hSNP patterns were highly distinct. INH-, RIF-, and PZA-associated hSNPs typically occurred as multiple low-frequency variants, whereas FQ- and SM-associated hSNPs predominantly appeared as single-site variants. Evolutionary modelling indicated that resistance to INH and RIF is generally acquired early, followed by SM and EMB resistance. In the inferred resistance-acquisition pathways, INH resistance was frequently followed by EMB resistance, whereas RIF resistance was positively associated with subsequent SM resistance. In contrast, resistance to PZA, EMB, or SM was associated with a reduced probability of subsequent ETO resistance. The overall genomic clustering rate was 20.98%, and ongoing microevolution within transmission clusters was commonly observed, characterized by the emergence of new resistant variants. These findings elucidate the evolutionary dynamics of multidrug-resistant tuberculosis, emphasizing structured resistance accumulation and within-host heterogeneity with implications for surveillance and treatment optimization.
Background Staphylococcus argenteus (S. argenteus) is a recently described member of the Staphylococcus aureus complex (SAC) that is increasingly associated with human infections worldwide. To date, data on its prevalence and genomic characteristics in Saudi Arabia have not been investigated. This study aimed to determine the prevalence of S. argenteus in a tertiary care setting and characterize its genomic features. Methods Species identification and antimicrobial susceptibility testing were performed using the updated Bruker MALDI-TOF MS, BD Phoenix, and VITEK 2 systems as part of routine clinical microbiology diagnostics. Genome sequencing was conducted to define the genetic characteristics and assess phylogenetic relationships. Results Eight S. argenteus isolates were identified among 400 SAC isolates collected between July and September 2025, showing 2% prevalence. The isolates were recovered from diverse clinical specimens and remained largely susceptible to common antibiotics. All isolates harbored blaZ and fusB genes on rep20-containing plasmids, conferring penicillin and fusidic acid resistance, respectively, and had the fosfomycin resistance gene fosB chromosomally located. All isolates carried immune evasion genes (sak and scn) and lacked those encoding Panton-Valentine leukocidin (PVL) and toxic shock syndrome toxin (TSST-1). Phylogenetic analysis revealed high genetic diversity among the Saudi isolates, while still forming a distinct cluster within the global ST2250 population. Conclusion This study provides the first genomic insight into S. argenteus in Saudi Arabia and establishes a baseline for future surveillance to better define its regional epidemiology and clinical relevance.
Streptococcus mutans (S. mutans) is a major cariogenic bacterium. However, its geographic population structure remains poorly characterized. This study included 728 clinical strains collected by our team (339 from Bengbu and 389 from Guangzhou), of which 648 were newly isolated. Following sequence typing, 137 strains could not be assigned a sequence type (ST) due to genetic variations, whereas the remaining 591 strains were categorized into 153 STs, including 100 novel STs. These 591 strains (305 from Bengbu and 286 from Guangzhou isolates), together with 467 strains retrieved from the PubMLST database (5 Chinese strains with unspecified geographical location and 462 international strains from 13 countries), yielded 1,058 strains for genetic analysis. We found that the multilocus sequence typing (MLST) success rate was lower for strains from Guangzhou (73.5%) than for those from Bengbu (90.0%), with 27 STs shared between the two regions. The Guangzhou isolates exhibited significantly greater genetic diversity. Among the 462 international strains, 271 STs were identified. Although 23 STs were shared between Chinese and international isolates, considerable population stratification was observed. ST2 was the most prevalent ST. However, it was detected in only 35 of 1,058 strains (3.3%). Genetic variation was significantly associated with isolation site (plaque vs. saliva) and serotype (c/e vs. f/k), but not with caries status. Overall, the findings indicate a high level of population diversity in S. mutans, the absence of dominant global epidemic strains, and no association between ST and caries status.
Enterohemorrhagic Escherichia coli (EHEC) are important human pathogens causing serious human diseases such as bloody diarrhea, hemorrhagic colitis and hemolytic-uremic syndrome (HUS). In recent years, the consumption of minimally processed products, such as fresh produce, has been increasingly associated with outbreaks of E. coli O157:H7 involving the development of HUS. Alternatives to the classical preservatives for prevention of EHEC transmission to humans, such as the use of strictly lytic phages are considered as powerful tools for the biocontrol of EHEC. In the current study, the two tailed bacteriophages vB_EcoS_MM-1 (MM-1) and vB_EcoS_MM-2 (MM-2) were isolated from a local sewage water plant. Genome analysis revealed that both phages belong to the genus Tequintavirus and contain a double-stranded DNA genome of approximately 118,000 bp. Phenotypic characterization revealed that both phages infect important clinical EHEC, food-borne STEC and Salmonella enterica serotypes. MM-1 and MM-2 were infectious at a broad temperature (4°C to 60 °C) and pH range (pH 3-12). Both phages combine a short latent period of appr. 15-20 min with a burst size of appr. 100 PFU mL-1. Growth of E. coli O157:H7 strain EDL933 was inhibited effectively by both phages. The analysis of Shiga toxin 2a gene expression using different MOIs did not reveal significant upregulation after phage infection compared to the non-infected control, even in the presence of subinhibitory concentrations of the SOS response-inducing antibiotic norfloxacin. This study highlights that vB_EcoS_MM-1 and vB_EcoS_MM-2 are promising and effective biocontrol agents against EHEC for further use in food safety applications and phage therapy.
Epstein-Barr virus (EBV), a member of gamma herpesvirus subfamily, infects more than 90% of the people in the world. There are some studies on EBV-mediated regulation of type I interferon (IFN-I) signaling, however, the underlying mechanism is still not fully understood. In this study, we demonstrated that the EBV encoded tegument protein BKRF4 could suppress RIG-I-like receptor (RLR) signaling pathway-induced IFN-β promoter activity and the mRNA transcription of IFN-β and downstream IFN-stimulated genes, which is favorable for RNA and DNA viral replications. Mechanically, BKRF4 was shown to interact with IRF3 and restrain its phosphorylation, dimerization, and nuclear translocation. Specifically, aa71-95 of BKRF4 was essential for its association with IRF3 and the inhibition of IFN-β promoter activity. Moreover, BKRF4 also could interplay with activated IRF7 but didn’t affect the formation of IRF7 homodimer or IRF3/IRF7 heterodimer, yet it could impede the nuclear accumulation of IRF7. In addition, knockdown of BKRF4 during EBV lytic replication significantly enhanced IFN-β promoter activity and the phosphorylation and dimerization of IRF3. Taken together, our findings suggested that BKRF4 could negatively regulate the RLR-mediated IFN-β antiviral signaling, which provides new evidence for the molecular mechanism exploited by EBV to evade the host innate immunity.
Polymicrobial infections are known to be associated with increased infection severity and poor clinical outcomes. In this study, we investigated the effect of co-infection with Gram-negative bacteria on the survival of Staphylococcus aureus. In vitro time-kill assays were performed on S. aureus monoculture and co-cultures with three Gram-negative bacteria, Acinetobacter baumannii, Escherichia coli, and Klebsiella pneumoniae, treated with ciprofloxacin and vancomycin. Cultures of Gram-negative bacteria were separated into cell pellets and supernatant and the survival of S. aureus was measured in each fraction. The effect of cell density of Gram-negative bacteria on the survival of S. aureus was also investigated. Intracellular ATP concentration and expression of rsh were examined in surviving S. aureus cells from the in vitro time-kill assays. The survival of S. aureus against ciprofloxacin and vancomycin increased when co-cultured with the Gram-negative bacterial species. Enhanced survival was observed only in co-cultures containing cell pellets, not in cell-free culture medium. With increased cell density of Gram-negative bacteria, the survival of S. aureus tended to increase. Low intracellular ATP concentrations and increased rsh expression were detected when S. aureus was co-cultured with A. baumannii. S. aureus showed increased survival against antibiotics in co-culture with several Gram-negative bacterial pathogens compared to monoculture, which was not attributable to their secreted factors. Increased antibiotic persistence in polymicrobial infections may be a significant cause of antibiotic treatment failure.
