Next-generation sequencing technologies and their application to the study and control of bacterial infections

Genomics for antimicrobial resistance-progress and future directions

Antimicrobial resistance (AMR) is a critical global public health threat, with bacterial pathogens of primary concern. Pathogen genomics has revolutionized the study of bacterial pathogens and provided deep insights into the mechanisms and dissemination of AMR, with the precision of whole-genome sequencing informing better control strategies. However, generating actionable data from genomic surveillance and diagnostic efforts requires integration at the public health and clinical interface that goes beyond academic efforts to identify resistance mechanisms, undertake post hoc analyses of outbreaks, and share data after research publications. In addition to timely genomics data, consideration also needs to be given to epidemiological sampling frames, analysis, and reporting mechanisms that meet International Organization for Standardization (ISO) standards and generation of reports that are interpretable and actionable for public health and clinical "end-users." Importantly, ensuring all countries have equitable access to data and technology is critical, through timely data sharing following the FAIR principles (findable, accessible, interoperable, and re-usable). In this review, we describe (i) advances in genomic approaches for AMR research and surveillance to understand emergence, evolution, and transmission of AMR and the key requirements to enable this work and (ii) discuss emerging and future applications of genomics at the clinical and public health interface, including barriers to implementation. Harnessing advances in genomics-enhanced AMR research and embedding robust and reproducible workflows within clinical and public health practice promises to maximize the impact of pathogen genomics for AMR globally in the coming decade.

Compatibility of whole-genome sequencing data from Illumina and Ion Torrent technologies in genome comparison analysis of Listeria monocytogenes

Whole-genome sequencing (WGS) has become the key approach for molecular surveillance of Listeria monocytogenes. Genome comparison analysis can reveal transmission routes that cannot be found with classic epidemiology. A widespread standard for use in genome comparison analysis involves data from short-read sequencing, generated on Illumina or Ion Torrent devices. To date, little is known about the compatibility of data from both platforms. This knowledge is essential when it comes to the central analysis of data, for example, in the case of outbreaks. We used WGS data from 47 L. monocytogenes isolates of the strain collection of the German National Reference Laboratory for L. monocytogenes, generated on either Illumina or Ion Torrent devices, to analyse the impact of the sequencing technology on downstream analyses. In our study, only the assembler SPAdes delivered qualitatively comparable results. In the gene-based core genome multilocus sequence typing (cgMLST), the same-strain allele discrepancy between the platforms was 14.5 alleles on average, which is well above the threshold of 7 alleles routinely used for cluster detection in L. monocytogenes. An application of a strict frameshift filter in cgMLST analysis could push the mean discrepancy below this threshold but reduced discriminatory power. The impact of the platform on the read-based single nucleotide polymorphism analysis was lower than that on the cgMLST. Overall, it was possible to improve compatibility in various ways, but perfect compatibility could not be achieved.

Lessons from 5 Years of Routine Whole-Genome Sequencing for Epidemiologic Surveillance of Shiga Toxin-Producing Escherichia coli, France, 2018-2022

Whole-genome sequencing (WGS) is routine for surveillance of Shiga toxin-producing Escherichia coli human isolates in France. Protocols use EnteroBase hierarchical clustering at <5 allelic differences (HC5) as screening for cluster detection. We assessed current implementation after 5 years for 1,002 sequenced isolates. From genomic distances of serotypes O26:H11, O157:H7, O80:H2, and O103:H2, we determined statistical thresholds for cluster determination and compared those with HC5 clusters. Thresholds varied by serotype, 5-16 allelic distances and 15-20 single-nucleotide polymorphisms, showing limits of a single-threshold approach. We confirmed validity of HC5 screening for 3 serotypes because statistical thresholds had limited effect on isolate clustering (high sensitivity and specificity). For O80:H2, results suggest that HC5 is less reliable, and other approaches should be explored. Public health officials should regularly assess WGS used for Shiga toxin-producing E. coli surveillance to account for serotype and genomic evolution and to interpret WGS-linked isolates in light of epidemiologic data.

Whole-Genome Shotgun Sequencing from Chicken Clinical Tracheal Samples for Bacterial and Novel Bacteriophage Identification

A whole-genome shotgun sequencing (sWGS) approach was applied to chicken clinical tracheal swab samples during metagenomics investigations to identify possible microorganisms among poultry with respiratory diseases. After applying shotgun sequencing, Ornithobacterium rhinotracheale (ORT) and a putative prophage candidate were found in one of the swab samples. A multi-locus sequence typing (MLST) scheme of the ORT genome involved the adk, aroE, fumC, gdhA, pgi, and pmi genes. Antibiotic resistant analysis demonstrated tetracycline-resistan t ribosomal protection protein, tetQ, the aminoglycoside-(3)-acetyltransferase IV gene, aminoglycoside antibiotic inactivation and macrolide resistance, and the ermX gene in the ORT genome. A putative prophage candidate was predicted using Prophage Hunter and PHAST, while BLAST analyses were utilized to identify genes encoding bacteriophage proteins. Interestingly, genes encoding endolysins were detected in bacteriophage genomes. The gene products encoded in the prophage sequence were most closely related to bacteriophages in the N4-like family among the Authographiviridae in the Caudovirales. This study demonstrates the potential of sWGS for the rapid detection and characterization of etiologic agents found in clinical samples.

Assessing the Influence of Selected Permeabilization Methods on Lymphocyte Single-Cell Multi-Omics

(1) Background: Single-cell multi-omics is a powerful method for the dissection and detection of complicated immunologic functions and synapses. However, most currently available technologies merge datasets of different omics from separate portions of the same sample to generate combined multi-omics. This process is a source of bias, mainly in the field of immunology on cells originating from pluripotent hematopoietic stem cells with high flexibility during maturation. (2) Methods: Although new multi-omics approaches have been developed to use the advantages of cellular and molecular barcoding and next-generation sequencing to solve this issue, one of the main current challenges is intracellular proteomics, which should be combined with other omics data with high importance for immune system studies. We designed this study to evaluate previously recommended minimal permeabilization and fixation methods on the quality and quantity of transcriptomics and proteomics data generated by the BD Rhapsody™ Single-Cell Analysis System. (3) Results: Our findings showed that high-throughput sequencing with advanced quality and read-out is required for the combination of multi-omics outcomes from a permeabilized single cell. Therefore, the HiseqX platform was selected for further analysis. The effect of immune stimulation was observed clearly as the separated clusters of helper and cytotoxic T cells using unsupervised clustering. Importantly, fixation and permeabilization did not affect the general expression profile of unstimulated cells. However, fixation and permeabilization were proved to negatively impact the detection of the whole transcriptome for single-cell assay. Nevertheless, about 60% of the transcriptomic signature of the stimulation was detected. If the measurement of combined surface and intracellular markers is required to be achieved, the modified fixation and permeabilization method is recommended because of a lower transcriptomic loss and more precise proteomic fingerprint detected. (4) Conclusions: The findings of this study support the potential possibility for integrating intracellular proteomics, which needs to be optimized and tested with newly designed oligonucleotide-tagged antibodies targeting intracellular proteins.

Comparison of commercial next-generation sequencing assays to conventional culture methods for bacterial identification and antimicrobial susceptibility of samples obtained from clinical cases of canine superficial bacterial folliculitis

BACKGROUND

Bacterial identification and antimicrobial susceptibility testing is an important step in timely therapeutic decisions for canine superficial bacterial folliculitis (SBF), commonly caused by Staphylococcus pseudintermedius. Next-generation sequencing (NGS) offers the appeal of potentially expedited results with complete detection of bacterial organisms and associated resistance genes compared to culture. Limited studies exist comparing the two methodologies for clinical samples.

HYPOTHESIS/OBJECTIVES

To compare and contrast genotypic and phenotypic methods for bacterial identification and antimicrobial susceptibility from cases of canine SBF.

ANIMALS

Twenty-four client-owned dogs with lesions consistent with SBF were enrolled.

MATERIALS AND METHODS

A sterile culturette swab was used to sample dogs with SBF lesions. The swab was rinsed in 0.9 mL of sterile phosphate-buffered saline and vortexed to create a homogenous solution. Two swabs for NGS laboratories (Labs) and one swab for culture (Culture Lab) were randomly sampled from this solution and submitted for bacterial identification and antimicrobial susceptibility.

RESULTS

No statistical difference regarding turnaround time for NGS Labs compared to Culture Lab was found. NGS Lab 1 identified more organisms than NGS Lab 2 and Culture Lab, which were both statistically significant. There was no statistical difference in detection frequency for Staphylococcus spp. among all laboratories. There was poor agreement for the presence of meticillin resistance and most antimicrobials among all laboratories.

CONCLUSIONS AND CLINICAL RELEVANCE

Utilisation of NGS as a replacement for traditional culture when sampling canine SBF lesions is not supported at this time.

Analysis of the efficacy of MALDI-TOF MS technology in identifying microorganisms in cancer patients and oncology hospital environment

Rapid diagnostics of microbes in hospitals are crucial for promptly identifying infections, enabling timely and appropriate treatment. The study was conducted to evaluate the effectiveness of the matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI TOF MS) technology in the microbial profiling of hospital environments and patient samples. The objective was to determine the microbial landscape in swabs collected from hospitalized patients and their immediate environments, using MALDI to compare the capabilities of two systems: BRUKER and ZYBIO. The analysis resulted in 1012 microbial identifications from patient samples (N = 81), encompassing 96 species, and 1496 identifications from hospital surface samples (N = 108), covering 124 species. Predominantly identified microorganisms in patients' samples included Staphylococcus epidermidis, Staphylococcus aureus, Staphylococcus capitis, Steptococcus salivarius, and Micrococcus luteus, whereas environmental samples chiefly yielded S. epidermidis, Staphylococcus hominis, Staphylococcus warneri, and Microcccus luteus. 33 species were found in both types of samples, highlighting a significant microbial interchange within hospital settings. Both MALDI systems showed high consistency in results at both genus and species levels. Nevertheless, mismatches in identification between both MALDI systems were noted, particularly within Brevibacterium, Streptococcus, Bacillus, Staphylococcus, and Neisseria genera. This study presents the precision of MALDI technology in microbial identification and highlights the need for ongoing enhancements, especially in the expansion and updating of databases, to bolster its diagnostic effectiveness further.

Disseminated organ and tissue infection secondary to carbapenem-resistant Klebsiella pneumoniae bloodstream infection for acute lymphoblastic leukemia treated with ceftazidime-avibactam: Two case reports

RATIONALE

Carbapenem-resistant Klebsiella pneumoniae (CRKP) bloodstream infections are a severe complication resulting from granulocyte deficiency following chemotherapy for hematologic malignancies and have a high mortality rate. However, reports of disseminated organ infections secondary to bloodstream infections are rare.

PATIENT CONCERNS AND DIAGNOSES

We report 2 cases of patients with acute lymphoblastic leukemia who both developed CRKP bloodstream infections during the granulocyte deficiency stage following chemotherapy, with 1 case of secondary bacterial liver abscess and 1 case of secondary septic arthritis.

INTERVENTIONS AND OUTCOMES

Based on the results of drug sensitivity testing, both patients were treated with ceftazidime-avibactam, and the infections were rapidly and effectively controlled without significant adverse effects.

LESSONS

Ceftazidime-avibactam exhibited satisfactory efficacy and safety in the 2 cases of disseminated organ infection secondary to CRKP bloodstream infection following chemotherapy for acute lymphoblastic leukemia.

Virtual Gram staining of label-free bacteria using dark-field microscopy and deep learning

Gram staining has been a frequently used staining protocol in microbiology. It is vulnerable to staining artifacts due to, e.g., operator errors and chemical variations. Here, we introduce virtual Gram staining of label-free bacteria using a trained neural network that digitally transforms dark-field images of unstained bacteria into their Gram-stained equivalents matching bright-field image contrast. After a one-time training, the virtual Gram staining model processes an axial stack of dark-field microscopy images of label-free bacteria (never seen before) to rapidly generate Gram staining, bypassing several chemical steps involved in the conventional staining process. We demonstrated the success of virtual Gram staining on label-free bacteria samples containing Escherichia coli and Listeria innocua by quantifying the staining accuracy of the model and comparing the chromatic and morphological features of the virtually stained bacteria against their chemically stained counterparts. This virtual bacterial staining framework bypasses the traditional Gram staining protocol and its challenges, including stain standardization, operator errors, and sensitivity to chemical variations.

First report on comprehensive genomic analysis of a multidrug-resistant Enterobacter asburiae isolated from diabetic foot infection from Bangladesh

Enterobacter asburiae (E. asburiae) is a gram-negative rod-shaped bacterium which has emerging significance as an opportunistic pathogen having high virulence pattern and drug resistant properties. In this study, we present the detailed analysis of the whole genome sequence of a multidrug-resistant (MDR) E. asburiae strain BDW1M3 from Bangladesh. The isolate was collected from an infected foot wound of a diabetic foot ulcer patient. Through sophisticated genomic techniques encompassing whole genome sequencing and in-depth bioinformatic analyses, this research unveils a profound understanding of the isolate's antimicrobial resistance patterns, virulence determinants, biosynthetic gene clusters, metabolic pathways and pathogenic potential. The isolate displayed resistance to Ampicillin, Fosfomycin, Cefoxitin, Tigecycline, Meropenem, Linezolid, Vancomycin antibiotics and demonstrated the capacity for biofilm formation. Several antimicrobial resistance genes such as blaACT-2,fosA2, baeR, qnrE2, vanA and numbers of virulence genes including ybaJ, csrA, barA, uvrY, pgaD, hlyD, hlyC, terC, purD were detected. Metal resistance genes investigation revealed the presence of cusCFBA operon system, and many other genes including zntA, zitB, czrB. Prophage region of Myoviridae was detected. Comparative genomics with 47 whole genome sequence (n = 47) shed light on the genetic diversity of E. asburiae strains from diverse sources and countries, with a notable observation that strains from both human and non-human origins exhibited significant pathogenicity potential, genomic and phylogenomic relations hinting at potential cross-species transmission. Pangenome analysis indicated toward an expanding pangenome of E. asburiae. Further research and in-depth comprehensive studies are required to investigate the prevalence of E. asburiae in Bangladesh and emphasize towards unraveling the bacterium's inherent pathogenic potential and the intricate molecular mechanisms that underlie its resistance traits and virulence properties.

Host associations of Campylobacter jejuni and Campylobacter coli isolates carrying the L-fucose or d-glucose utilization cluster

Campylobacter was considered asaccharolytic, but is now known to carry saccharide metabolization pathways for L-fucose and d-glucose. We hypothesized that these clusters are beneficial for Campylobacter niche adaptation and may help establish human infection. We investigated the distribution of d-glucose and L-fucose clusters among ∼9600 C. jejuni and C. coli genomes of different isolation sources in the Netherlands, the United Kingdom, the United States of America and Finland. The L-fucose utilization cluster was integrated at the same location in all C. jejuni and C. coli genomes, and was flanked by the genes rpoB, rpoC, rspL, repsG and fusA, which are associated with functions in transcription as well as translation and in acquired drug resistance. In contrast, the flanking regions of the d-glucose utilization cluster were variable among the isolates, and integration sites were located within one of the three different 16S23S ribosomal RNA areas of the C. jejuni and C. coli genomes. In addition, we investigated whether acquisition of the L-fucose utilization cluster could be due to horizontal gene transfer between the two species and found three isolates for which this was the case: one C. jejuni isolate carrying a C. coli L-fucose cluster, and two C. coli isolates which carried a C. jejuni L-fucose cluster. Furthermore, L-fucose utilization cluster alignments revealed multiple frameshift mutations, most of which were commonly found in the non-essential genes for L-fucose metabolism, namely, Cj0484 and Cj0489. These findings support our hypothesis that the L-fucose cluster was integrated multiple times across the C. coli/C. jejuni phylogeny. Notably, association analysis using the C. jejuni isolates from the Netherlands showed a significant correlation between human C. jejuni isolates and C. jejuni isolates carrying the L-fucose utilization cluster. This correlation was even stronger when the Dutch isolates were combined with the isolates from the UK, the USA and Finland. No such correlations were observed for C. coli or for the d-glucose cluster for both species. This research provides insight into the spread and host associations of the L-fucose and d-glucose utilization clusters in C. jejuni and C. coli, and the potential benefits in human infection and/or proliferation in humans, conceivably after transmission from any reservoir.

Antimicrobial susceptibility and resistome of Actinobacillus pleuropneumoniae in Taiwan: a next-generation sequencing analysis

Actinobacillus pleuropneumoniae infection causes a high mortality rate in porcine animals. Antimicrobial resistance poses global threats to public health. The current study aimed to determine the antimicrobial susceptibilities and probe the resistome of A. pleuropneumoniae in Taiwan. Herein, 133 isolates were retrospectively collected; upon initial screening, 38 samples were subjected to next-generation sequencing (NGS). Over the period 2017-2022, the lowest frequencies of resistant isolates were found for ceftiofur, cephalexin, cephalothin, and enrofloxacin, while the highest frequencies of resistant isolates were found for oxytetracycline, streptomycin, doxycycline, ampicillin, amoxicillin, kanamycin, and florfenicol. Furthermore, most isolates (71.4%) showed multiple drug resistance. NGS-based resistome analysis revealed aminoglycoside- and tetracycline-related genes at the highest prevalence, followed by genes related to beta-lactam, sulfamethoxazole, florphenicol, and macrolide. A plasmid replicon (repUS47) and insertion sequences (IS10R and ISVAp11) were identified in resistant isolates. Notably, the multiple resistance roles of the insertion sequence IS10R were widely proposed in human medicine; however, this is the first time IS10R has been reported in veterinary medicine. Concordance analysis revealed a high consistency of phenotypic and genotypic susceptibility to florphenicol, tilmicosin, doxycycline, and oxytetracycline. The current study reports the antimicrobial characterization of A. pleuropneumoniae for the first time in Taiwan using NGS.

A Systematic Review and Meta-Analysis of Molecular Characteristics on Colistin Resistance of Acinetobacter baumannii

BACKGROUND

This study aimed to determine the molecular epidemiology of colistin-resistant A. baumannii in the last ten years and the frequency of gene regions related to pathogenesis, to compare the methods used to detect genes, and to confirm colistin resistance.

METHODS

This meta-analysis study was conducted under Preferred Reporting Items for Systematic Reviews and Meta-Analysis Guidelines. In the meta-analysis, research articles published in English and Turkish in electronic databases between January 2012 and November 2023 were examined. International Business Machines (IBM) Statistical Package for the Social Sciences (SPSS) Statistics for Macbook (Version 25.0. Armonk, NY, USA) was used for statistical analysis. The Comprehensive Meta-Analysis (CMA) (Version 3.0. Biostat, NJ, USA) program was used for heterogeneity assessment in the articles included in the meta-analysis.

RESULTS

After evaluating the studies according to the elimination criteria, 18 original articles were included. Among colistin-resistant strains, blaOXA-51 positivity was 243 (19.61%), blaOXA-23 was 113 (9.12%), blaOXA-58 was 7 (0.56%), blaOXA-143 was 15 (1.21%), and blaOXA-72 was seen in two (0.16%) strains. The positivity rates of pmrA, pmrB, and pmrC were found to be 22 (1.77%), 26 (2.09%), and 6 (0.48%). The mcr-1 rate was found to be 91 (7.34%), the mcr-2 rate was 78 (6.29%), and the mcr-3 rate was 82 (6.61%).

CONCLUSIONS

The colistin resistance rate in our study was found to be high. However, only some research articles report and/or investigate more than one resistance gene together. Additionally, it may be challenging to explain colistin resistance solely by expressing resistance genes without discussing accompanying components such as efflux pumps, virulence factors, etc.

Advancing pathogen and tumor copy number variation detection through simultaneous metagenomic next-generation sequencing: A comprehensive review

In clinical practice, timely and accurate diagnosis can effectively reduce unnecessary treatment, avoid high medical costs, and prevent adverse prognoses. However, some patients with malignant tumors and those with infection often exhibit similar symptoms, which are difficult to distinguish, posing challenges in accurate clinical diagnosis. Metagenomic next-generation sequencing (mNGS) technology has been widely applied to confirm the source of infection. Recent studies have shown that for pathogen detection, mNGS technology can be used to perform chromosomal copy number variations (CNVs) analysis in two different analytical pipelines using the same wet test. mNGS technology has further demonstrated its utility in not only the determination of pathogenic microorganisms but also of CNVs, thereby facilitating early differential diagnosis for malignant tumors. In this review, we aim to analyze the diagnostic performance of mNGS technology in the simultaneous detection of pathogenic microorganisms and CNVs in current clinical practice and discuss the advantages and limitations of mNGS-CNV dual-omics detection technology. Our review highlights the need for more large-scale prospective research data on current mNGS-CNV dual-omics detection technology to provide more evidence-based results for researchers and clinicians and to promote the greater role of this technology in future clinical practice.

Metagenomic next-generation sequencing of osteoarticular tissue for the diagnosis of suspected osteoarticular tuberculosis

The objective of the study is to determine the accuracy of metagenomic next-generation sequencing (mNGS) in diagnosing osteoarticular tuberculosis (TB) infection and to compare it with mycobacteria growth indicator tube (MGIT) and Xpert assays. We retrospectively analyzed 162 patients admitted with suspected osteoarticular TB. Osteoarticular tissue (66.67%) and abscess specimens (33.33%) from patients were tested for MGIT, GeneXpert/RIF, and mNGS. mNGS assay detected 76 cases (46.9%) with bacterial, 63 cases (38.9%) with mycobacterial, 22 cases (13.6%) with fungal, and 1 case (0.6%) with actinomycetal organisms. These 162 pathogens were classified into 21 species. The most frequent species detected was Mycobacterium tuberculosis complex (29.0%), followed by Staphylococcus aureus (20.4%), Mycobacterium abscessus (5.6%), and Candida albicans (5.6%). Taking the "gold standard" TB diagnosis as the standard, the positive predictive values of mNGS, Xpert, and MGIT culture were both 100.00%. The negative predictive values of mNGS, Xpert, and MGIT culture and assays were 94.26%, 98.29%, and 88.46%, respectively. The sensitivity of mNGS detection (85.11%) was similar to that of Xpert (95.74%) and higher than that of MGIT culture (68.08%). The specificities of mNGS detection, Xpert, and MGIT culture were both 100.00%. The area under the curve value of the mNGS assay was 0.895 (95% CI: 0.830, 0.960), which was greater than that of the MGIT culture-based assay of 0.840 (95% CI: 0.757, 0.924), which was similar to 0.979 (95% CI: 0.945, 1.000) for Xpert assay. The pathogen detection rate of mNGS in diagnosing suspected osteoarticular TB exceeded that of conventional methods.

IMPORTANCE

In the detection of unknown infectious disease pathogens, the overall efficacy of traditional detection methods, such as culture, is low, and traditional PCR testing is also limited to the gene sequences of known pathogenic microorganisms. Metagenomic next-generation sequencing (mNGS) performs DNA sequencing by studying the entire microbial community genome in a given sample, without the need for isolation and culture. Previous studies have shown that mNGS performs better on pulmonary and extrapulmonary samples when compared with Xpert, traditional pathogenetic tests, and even parallel diagnostics. However, it should be emphasized that only a few studies have explored the performance of mNGS in detecting Mycobacterium tuberculosis in clinical samples associated with bone and joint infections. We conducted this retrospective study to provide additional data to support the use of mNGS in the clinical setting to identify pathogens within abscesses or tissue samples associated with bone and joint infections.

Metagenomic analysis of pathogenic bacteria and virulence factor genes in coastal sediments from highly urbanized cities of India

A metagenomic approach was employed to investigate the diversity and distribution of Virulence Factors Genes (VFGs) and Pathogenic Bacteria (PB) in sediment samples collected from highly urbanized cities along the Indian coastline. Among the study locations, Mumbai, Veraval and Paradeep showed a higher abundance of PB, with Vibrio and Pseudomonas as dominant at the genus level, and Escherichia coli and Pseudomonas aeruginosa at the species level. In total, 295 VFGs were detected across all sediment samples, of which 40 VFGs showed a similarity of ≥90 % with the Virulence Database (VFDB) and were focused in this study. Among the virulent proteins, twitching motility protein and flagellar P-ring were found to be prevalent and significantly associated with Vibrio spp., and Pseudomonas spp., indicating potential bacterial pathogenicity. This investigation serves as the basis for future studies and provides insights into the comprehensive taxonomic profiles of PB, VFGs and their associated PB in the coastal sediments of India.

Exploring microbial worlds: a review of whole genome sequencing and its application in characterizing the microbial communities

The classical microbiology techniques have inherent limitations in unraveling the complexity of microbial communities, necessitating the pivotal role of sequencing in studying the diversity of microbial communities. Whole genome sequencing (WGS) enables researchers to uncover the metabolic capabilities of the microbial community, providing valuable insights into the microbiome. Herein, we present an overview of the rapid advancements achieved thus far in the use of WGS in microbiome research. There was an upsurge in publications, particularly in 2021 and 2022 with the United States, China, and India leading the metagenomics research landscape. The Illumina platform has emerged as the widely adopted sequencing technology, whereas a significant focus of metagenomics has been on understanding the relationship between the gut microbiome and human health where distinct bacterial species have been linked to various diseases. Additionally, studies have explored the impact of human activities on microbial communities, including the potential spread of pathogenic bacteria and antimicrobial resistance genes in different ecosystems. Furthermore, WGS is used in investigating the microbiome of various animal species and plant tissues such as the rhizosphere microbiome. Overall, this review reflects the importance of WGS in metagenomics studies and underscores its remarkable power in illuminating the variety and intricacy of the microbiome in different environments.

Oral microbial profiles of extrinsic black tooth stain in primary dentition: A literature review

The extrinsic black tooth stain (EBS) is commonly found in primary dentition. Patients cannot clean the EBS; this can only be done by professional scaling and debridement. It also has a tendency to reform, which significantly compromises children's aesthetics and even affects their quality of life. However, there is no conclusive evidence on the etiology of the EBS. The associations between the EBS and related oral microbial features is one of the research hot topics. No literature review summarized these research progresses in this area. Therefore, we reviewed the literature on the microbiology of the EBS since 1931 and reported as the following 5 aspects: molecular biotechnology, morphological structure and physiochemical characteristics, microbial etiology hypothesis and core microbial characteristics. The EBS is a special dental plaque mainly composed of Gram-positive bacilli and cocci with scattered calcium deposits that acquired salivary pellicle activates. Early studies showed that the Actinomyces was the main pathogenic bacteria. With advances in biological research techniques, the 'core microbiome' was proposed. The potential pathogenic genera were Actinomyces, Prevotella nigrescens, Pseudotropinibacterium, Leptotrichia, Neisseria and Rothia. However, the pathogenic species of the above genera were still unclear. Currently, it is believed that the EBS consists of iron compounds or black substances that oral bacterial metabolism produces or that the bacterial metabolites formed after chemical reactions in the micro-ecological environment.

The impact of neutrophil count on the results of metagenomic next-generation sequencing in immunocompromised febrile children

Metagenomic next-generation sequencing (mNGS) has revolutionized the detection of pathogens, particularly in immunocompromised individuals such as pediatric patients undergoing intensive chemotherapy and hematopoietic stem cell transplantation. This study aims to explore the impact of neutrophil count on the diagnostic efficacy of mNGS in diagnosing infections in pediatric patients with febrile diseases. We conducted a retrospective analysis of pediatric patients with febrile diseases in the hematology/oncology department from January 2019 to September 2022. The study included 387 patients with 516 febrile episodes. Analyzing data from 516 pediatric cases, our study found that 70.7 % had febrile neutropenia (FN) and 29.3 % had febrile without neutropenia (FWN). mNGS demonstrated a high positive detection rate of 84.9 %, compared to 29.7 % for conventional microbiological tests (CMT). While the positive detection rates of mNGS were similar in both FN and FWN groups, bacterial pathogens were more frequently detected in FN patients. Furthermore, the rate of identifying a "probable" microbial etiology was lower in the FN group (46.8 %) compared to the FWN group (65.6 %, p＜0.001). When analyzing the types of organisms and specimens, the "probable" identification rates were particularly lower for viruses and fungi detected by mNGS, as well as in blood and nasopharyngeal swab samples. These findings underscore the significant influence of neutrophil counts on mNGS results in pediatric febrile patients and highlight the necessity for tailored diagnostic approaches in this population.

Disseminated Acanthamoeba castellanii infection in a patient with AIDS: a case report and literature review

Background

Acanthamoeba castellanii infection is a rare condition primarily occurring in immunocompromised patients with extremely high mortality. Currently, there is no standard treatment for this condition, and successful treatment reports are scarce.

Case presentation

We present a case of Acanthamoeba castellanii infection in a 63-year-old female patient with AIDS, who was admitted to our hospital with symptoms of fever, skin ulcers, subcutaneous nodules, and food regurgitation from the nose while eating. After initial empirical treatment failed, a biopsy of the subcutaneous nodule was performed, and metagenomic next-generation sequencing (mNGS) technology was used to detect pathogenic microorganisms in both the biopsy specimen and blood samples. The results revealed Acanthamoeba castellanii infection. Additionally, histopathological examination of the biopsy specimen and cytological examination of the secretions from the ulcer surface also confirmed this pathogenic infection. The patient's symptoms significantly improved upon discharge after adjusting the treatment regimen to a combination of anti-amebic therapy.

Conclusion

Immunocompromised patients presenting with unexplained fever and skin or sinus lesions should be evaluated for Acanthamoeba castellanii infection. Multi-drug combination therapy is required for this organism infection, and a standard treatment protocol still needs further research. Metagenomic next-generation sequencing is a valuable tool for early diagnosis of unknown pathogen infections.

Comparison of plasma and blood cell samples in metagenomic next-generation sequencing for identification of the causative pathogens of fever

Background

Metagenomic next-generation sequencing (mNGS) of plasma DNA has become an attractive diagnostic method for infectious diseases; however, the rate of false-positive results is high. This study aims to evaluate the diagnostic accuracy of mNGS in plasma versus blood cell samples for immunocompromised children with febrile diseases.

Methods

The results of conventional microbiological test (CMT) and mNGS using plasma and blood cells in 106 patients with 128 episodes of febrile diseases from the Department of Hematology/Oncology were analyzed and described.

Results

The positivity rates for CMT and mNGS of plasma and blood cells were 35.9 %, 84.4 % and 46.9 %, respectively (P < 0.001). Notably, mNGS identified multiple pathogens in a single specimen in 68.5 % of plasma samples and 38.3 % of blood cell samples (P < 0.001). Furthermore, plasma and blood cell mNGS identified causative pathogens in 58 and 46 cases, accounting for 53.7 % and 76.7 % of the mNGS-positive cases for each sample type, respectively (P = 0.002). By integrating results from both plasma and blood cell samples, causative pathogens were identified in 77 cases (60.2 %), enhancing sensitivity to 87.5 % but reducing specificity to 15.0 %, compared to plasma (65.9 % sensitivity and 20.0 % specificity) and blood cell samples (52.3 % sensitivity and 80.0 % specificity).

Conclusions

mNGS of plasma is sensitive but has a high false-positive rate, while mNGS of blood cells has low sensitivity but higher specificity.

Complete circular assembly of Histophilus somni PDS1537697-81-1 genome and phenotypic characterization of its antibiotic susceptibility

A Histophilus somni isolate from a clinically healthy, fall-placed calf was obtained upon arrival to a commercial feedlot. Fall-placed calves are commonly viewed to be at high risk for the development of bovine respiratory disease. The isolate was phenotyped for antimicrobial susceptibility and sequenced to obtain a complete, circular, genome assembly.

Occurrence and genomic characterization of antimicrobial-resistant and potential pathogenic Escherichia coli from Italian artisanal food productions of animal origin

Escherichia coli can harbor a broad repertoire of virulence and antimicrobial resistance (AMR) genes, which can be exchanged across the human gastrointestinal microflora, thus posing a public health risk. In this study, 6 batches of artisanal soft cheese and a 6-month ripened fermented dried sausage were investigated to assess the occurrence, phylogeny, and genomic traits (AMR, virulence, and mobilome) of E. coli. 30 and 3 strains isolated from salami and cheese food chains, respectively, were confirmed as E. coli by whole genome sequencing. The accumulation of single nucleotide polymorphism differences within small clusters of strains encompassing batches or processing stages, combined with high serotype and phylogroup diversity, suggested the occurrence of different contamination phenomena among the facilities. A total of 8 isolates harbored plasmid-mediated resistance genes, including one cheese strain that carried an IncQ1 plasmid carrying AMR determinants to macrolides [mph(B)], sulfonamides (sul1, sul2), trimethoprim (dfrA1), and aminoglycosides [aph(3")-Ib and aph(6)-Id]. A pool of virulence-associated genes in the class of adhesion, colonization, iron uptake, and toxins, putative ColV-positive iron uptake systems sit, iro, or iuc (8 salami and 2 cheese), plasmid-encoded hemolysin operon hlyABCD (one salami), and potential atypical enteropathogenic E. coli (3 salami environment) were reported. Overall, our findings underscore the importance of routine surveillance of E. coli in the artisanal food chain to prevent the dissemination of AMR and virulence.

Omics technology draws a comprehensive heavy metal resistance strategy in bacteria

The rapid industrial revolution significantly increased heavy metal pollution, becoming a major global environmental concern. This pollution is considered as one of the most harmful and toxic threats to all environmental components (air, soil, water, animals, and plants until reaching to human). Therefore, scientists try to find a promising and eco-friendly technique to solve this problem i.e., bacterial bioremediation. Various heavy metal resistance mechanisms were reported. Omics technologies can significantly improve our understanding of heavy metal resistant bacteria and their communities. They are a potent tool for investigating the adaptation processes of microbes in severe conditions. These omics methods provide unique benefits for investigating metabolic alterations, microbial diversity, and mechanisms of resistance of individual strains or communities to harsh conditions. Starting with genome sequencing which provides us with complete and comprehensive insight into the resistance mechanism of heavy metal resistant bacteria. Moreover, genome sequencing facilitates the opportunities to identify specific metal resistance genes, operons, and regulatory elements in the genomes of individual bacteria, understand the genetic mechanisms and variations responsible for heavy metal resistance within and between bacterial species in addition to the transcriptome, proteome that obtain the real expressed genes. Moreover, at the community level, metagenome, meta transcriptome and meta proteome participate in understanding the microbial interactive network potentially novel metabolic pathways, enzymes and gene species can all be found using these methods. This review presents the state of the art and anticipated developments in the use of omics technologies in the investigation of microbes used for heavy metal bioremediation.

Legionella pneumophila exploits the endo-lysosomal network for phagosome biogenesis by co-opting SUMOylated Rab7

Legionella pneumophila strains harboring wild-type rpsL such as Lp02rpsLWT cannot replicate in mouse bone marrow-derived macrophages (BMDMs) due to induction of extensive lysosome damage and apoptosis. The bacterial factor directly responsible for inducing such cell death and the host factor involved in initiating the signaling cascade that leads to lysosome damage remain unknown. Similarly, host factors that may alleviate cell death induced by these bacterial strains have not yet been investigated. Using a genome-wide CRISPR/Cas9 screening, we identified Hmg20a and Nol9 as host factors important for restricting strain Lp02rpsLWT in BMDMs. Depletion of Hmg20a protects macrophages from infection-induced lysosomal damage and apoptosis, allowing productive bacterial replication. The restriction imposed by Hmg20a was mediated by repressing the expression of several endo-lysosomal proteins, including the small GTPase Rab7. We found that SUMOylated Rab7 is recruited to the bacterial phagosome via SulF, a Dot/Icm effector that harbors a SUMO-interacting motif (SIM). Moreover, overexpression of Rab7 rescues intracellular growth of strain Lp02rpsLWT in BMDMs. Our results establish that L. pneumophila exploits the lysosomal network for the biogenesis of its phagosome in BMDMs.

Variability and bias in microbiome metagenomic sequencing: an interlaboratory study comparing experimental protocols

Several studies have documented the significant impact of methodological choices in microbiome analyses. The myriad of methodological options available complicate the replication of results and generally limit the comparability of findings between independent studies that use differing techniques and measurement pipelines. Here we describe the Mosaic Standards Challenge (MSC), an international interlaboratory study designed to assess the impact of methodological variables on the results. The MSC did not prescribe methods but rather asked participating labs to analyze 7 shared reference samples (5 × human stool samples and 2 × mock communities) using their standard laboratory methods. To capture the array of methodological variables, each participating lab completed a metadata reporting sheet that included 100 different questions regarding the details of their protocol. The goal of this study was to survey the methodological landscape for microbiome metagenomic sequencing (MGS) analyses and the impact of methodological decisions on metagenomic sequencing results. A total of 44 labs participated in the MSC by submitting results (16S or WGS) along with accompanying metadata; thirty 16S rRNA gene amplicon datasets and 14 WGS datasets were collected. The inclusion of two types of reference materials (human stool and mock communities) enabled analysis of both MGS measurement variability between different protocols using the biologically-relevant stool samples, and MGS bias with respect to ground truth values using the DNA mixtures. Owing to the compositional nature of MGS measurements, analyses were conducted on the ratio of Firmicutes: Bacteroidetes allowing us to directly apply common statistical methods. The resulting analysis demonstrated that protocol choices have significant effects, including both bias of the MGS measurement associated with a particular methodological choices, as well as effects on measurement robustness as observed through the spread of results between labs making similar methodological choices. In the analysis of the DNA mock communities, MGS measurement bias was observed even when there was general consensus among the participating laboratories. This study was the result of a collaborative effort that included academic, commercial, and government labs. In addition to highlighting the impact of different methodological decisions on MGS result comparability, this work also provides insights for consideration in future microbiome measurement study design.

Illumina and Nanopore sequencing in culture-negative samples from suspected lower respiratory tract infection patients

Objective

To evaluate the diagnostic value of metagenomic sequencing technology based on Illumina and Nanopore sequencing platforms for patients with suspected lower respiratory tract infection whose pathogen could not be identified by conventional microbiological tests.

Methods

Patients admitted to the Respiratory and Critical Care Medicine in Shanghai Ruijin Hospital were retrospectively studied from August 2021 to March 2022. Alveolar lavage or sputum was retained in patients with clinically suspected lower respiratory tract infection who were negative in conventional tests. Bronchoalveolar lavage fluid (BALF) samples were obtained using bronchoscopy. Sputum samples were collected, while BALF samples were not available due to bronchoscopy contraindications. Samples collected from enrolled patients were simultaneously sent for metagenomic sequencing on both platforms.

Results

Thirty-eight patients with suspected LRTI were enrolled in this study, consisting of 36 parts of alveolar lavage and 2 parts of sputum. According to the infection diagnosis, 31 patients were confirmed to be infected with pathogens, while 7 patients were diagnosed with non-infectious disease. With regard to the diagnosis of infectious diseases, the sensitivity and specificity of Illumina and Nanopore to diagnose infection in patients were 80.6% vs. 93.5% and 42.9 vs. 28.6%, respectively. In patients diagnosed with bacterial, Mycobacterium, and fungal infections, the positive rates of Illumina and Nanopore sequencer were 71.4% vs. 78.6%, 36.4% vs. 90.9%, and 50% vs. 62.5%, respectively. In terms of pathogen diagnosis, the sensitivity and specificity of pathogens detected by Illumina and Nanopore were 55.6% vs. 77.8% and 42.9% vs. 28.6%, respectively. Among the patients treated with antibiotics in the last 2 weeks, 61.1% (11/18) and 77.8% (14/18) cases of pathogens were accurately detected by Illumina and Nanopore, respectively, among which 8 cases were detected jointly. The consistency between Illumina and diagnosis was 63.9% (23/36), while the consistency between Nanopore and diagnosis was 83.3% (30/36). Between Illumina and Nanopore sequencing methods, the consistency ratio was 55% (22/42) based on pathogen diagnosis.

Conclusion

Both platforms play a certain value in infection diagnosis and pathogen diagnosis of CMT-negative suspected LRTI patients, providing a theoretical basis for clinical accurate diagnosis and symptomatic treatment. The Nanopore platform demonstrated potential advantages in the identification of Mycobacterium and could further provide another powerful approach for patients with suspected Mycobacterium infection.

Comparative whole genome analysis of face-derived Streptococcus infantis CX-4 unravels the functions related to skin barrier

BACKGROUND

The skin microbiome is essential in guarding against harmful pathogens and responding to environmental changes by generating substances useful in the cosmetic and pharmaceutical industries. Among these microorganisms, Streptococcus is a bacterial species identified in various isolation sources. In 2021, a strain of Streptococcus infantis, CX-4, was identified from facial skin and found to be linked to skin structure and elasticity. As the skin-derived strain differs from other S. infantis strains, which are usually of oral origin, it emphasizes the significance of bacterial variation by the environment.

OBJECTIVE

This study aims to explore the unique characteristics of the CX-4 compared to seven oral-derived Streptococcus strains based on the Whole-Genome Sequencing data, focusing on its potential role in skin health and its possible application in cosmetic strategies.

METHODS

The genome of the CX-4 strain was constructed using PacBio Sequencing, with the assembly performed using the SMRT protocol. Comparative whole-genome analysis was then performed with seven closely related strains, utilizing web-based tools like PATRIC, OrthoVenn3, and EggNOG-mapper, for various analyses, including protein association analysis using STRING.

RESULTS

Our analysis unveiled a substantial number of Clusters of Orthologous Groups in diverse functional categories in CX-4, among which sphingosine kinase (SphK) emerged as a unique product, exclusively present in the CX-4 strain. SphK is a critical enzyme in the sphingolipid metabolic pathway, generating sphingosine-1-phosphate. The study also brought potential associations with isoprene formation and retinoic acid synthesis, the latter being a metabolite of vitamin A, renowned for its crucial function in promoting skin cell growth, differentiation, and maintaining of skin barrier integrity. These findings collectively suggest the potential of the CX-4 strain in enhancing of skin barrier functionality.

CONCLUSION

Our research underscores the potential of the skin-derived S. infantis CX-4 strain by revealing unique bacterial compounds and their potential roles on human skin.

Genomic revisitation and reclassification of the genus Providencia

Members of Providencia, although typically opportunistic, can cause severe infections in immunocompromised hosts. Recent advances in genome sequencing provide an opportunity for more precise study of this genus. In this study, we first identified and characterized a novel species named Providencia zhijiangensis sp. nov. It has ≤88.23% average nucleotide identity (ANI) and ≤31.8% in silico DNA-DNA hybridization (dDDH) values with all known Providencia species, which fall significantly below the species-defining thresholds. Interestingly, we found that Providencia stuartii and Providencia thailandensis actually fall under the same species, evidenced by an ANI of 98.59% and a dDDH value of 90.4%. By fusing ANI with phylogeny, we have reclassified 545 genomes within this genus into 20 species, including seven unnamed taxa (provisionally titled Taxon 1-7), which can be further subdivided into 23 lineages. Pangenomic analysis identified 1,550 genus-core genes in Providencia, with coenzymes being the predominant category at 10.56%, suggesting significant intermediate metabolism activity. Resistance analysis revealed that most lineages of the genus (82.61%, 19/23) carry a high number of antibiotic-resistance genes (ARGs) and display diverse resistance profiles. Notably, the majority of ARGs are located on plasmids, underscoring the significant role of plasmids in the resistance evolution within this genus. Three species or lineages (P. stuartii, Taxon 3, and Providencia hangzhouensis L12) that possess the highest number of carbapenem-resistance genes suggest their potential influence on clinical treatment. These findings underscore the need for continued surveillance and study of this genus, particularly due to their role in harboring antibiotic-resistance genes.

IMPORTANCE

The Providencia genus, known to harbor opportunistic pathogens, has been a subject of interest due to its potential to cause severe infections, particularly in vulnerable individuals. Our research offers groundbreaking insights into this genus, unveiling a novel species, Providencia zhijiangensis sp. nov., and highlighting the need for a re-evaluation of existing classifications. Our comprehensive genomic assessment offers a detailed classification of 545 genomes into distinct species and lineages, revealing the rich biodiversity and intricate species diversity within the genus. The substantial presence of antibiotic-resistance genes in the Providencia genus underscores potential challenges for public health and clinical treatments. Our study highlights the pressing need for increased surveillance and research, enriching our understanding of antibiotic resistance in this realm.

Enhancing Clinical Utility: Utilization of International Standards and Guidelines for Metagenomic Sequencing in Infectious Disease Diagnosis

Metagenomic sequencing has emerged as a transformative tool in infectious disease diagnosis, offering a comprehensive and unbiased approach to pathogen detection. Leveraging international standards and guidelines is essential for ensuring the quality and reliability of metagenomic sequencing in clinical practice. This review explores the implications of international standards and guidelines for the application of metagenomic sequencing in infectious disease diagnosis. By adhering to established standards, such as those outlined by regulatory bodies and expert consensus, healthcare providers can enhance the accuracy and clinical utility of metagenomic sequencing. The integration of international standards and guidelines into metagenomic sequencing workflows can streamline diagnostic processes, improve pathogen identification, and optimize patient care. Strategies in implementing these standards for infectious disease diagnosis using metagenomic sequencing are discussed, highlighting the importance of standardized approaches in advancing precision infectious disease diagnosis initiatives.

Whole Genome Sequencing: Applications in Clinical Bacteriology

The success in determining the whole genome sequence of a bacterial pathogen was first achieved in 1995 by determining the complete nucleotide sequence of Haemophilus influenzae Rd using the chain-termination method established by Sanger et al. in 1977 and automated by Hood et al. in 1987. However, this technology was laborious, costly, and time-consuming. Since 2004, high-throughput next-generation sequencing technologies have been developed, which are highly efficient, require less time, and are cost-effective for whole genome sequencing (WGS) of all organisms, including bacterial pathogens. In recent years, the data obtained using WGS technologies coupled with bioinformatics analyses of the sequenced genomes have been projected to revolutionize clinical bacteriology. WGS technologies have been used in the identification of bacterial species, strains, and genotypes from cultured organisms and directly from clinical specimens. WGS has also helped in determining resistance to antibiotics by the detection of antimicrobial resistance genes and point mutations. Furthermore, WGS data have helped in the epidemiological tracking and surveillance of pathogenic bacteria in healthcare settings as well as in communities. This review focuses on the applications of WGS in clinical bacteriology.

Genome-based assessment of antimicrobial resistance reveals the lineage specificity of resistance and resistance gene profiles in Riemerella anatipestifer from China

Riemerella anatipestifer (R. anatipestifer) is an important pathogen that causes severe systemic infections in domestic ducks, resulting in substantial economic losses for China's waterfowl industry. Controlling R. anatipestifer with antibiotics is extremely challenging due to its multidrug resistance. Notably, large-scale studies on antimicrobial resistance (AMR) and the corresponding genetic determinants in R. anatipestifer remain scarce. To solve this dilemma, more than 400 nonredundant R. anatipestifer isolates collected from 22 provinces in China between 1994 and 2021 were subjected to broth dilution antibiotic susceptibility assays, and their resistance-associated genetic determinants were characterized by whole-genome sequencing. While over 90% of the isolates was resistant to sulfamethoxazole, kanamycin, gentamicin, ofloxacin, norfloxacin, and trimethoprim, 88.48% of the isolates was resistant to the last-resort drug (tigecycline). Notably, R. anatipestifer resistance to oxacillin, norfloxacin, ofloxacin, and tetracycline was found to increase relatively over time. Genome-wide analysis revealed the alarmingly high prevalence of blaOXA-like (93.05%) and tet(X) (90.64%) genes and the uneven distribution of resistance genes among lineages. Overall, this study reveals a serious AMR situation regarding R. anatipestifer in China, with a high prevalence and high diversity of antimicrobial resistance genes, providing important data for the rational use of antibiotics in veterinary practice.IMPORTANCERiemerella anatipestifer (R. anatipestifer), an important waterfowl pathogen, has caused substantial economic losses worldwide, especially in China. Antimicrobial resistance (AMR) is a major challenge in controlling this pathogen. Although a few studies have reported antimicrobial resistance in R. anatipestifer, comprehensive data remain a gap. This study aims to address the lack of information on R. anatipestifer AMR and its genetic basis. By analyzing more than 400 isolates collected over two decades, this study reveals alarming levels of resistance to several antibiotics, including drugs of last resort. The study also revealed the lineage-specificity of resistance profiles and resistance gene profiles. Overall, this study provides new insights and updated data support for understanding AMR and its genetic determinants in R. anatipestifer.

Revealing the seed microbiome: Navigating sequencing tools, microbial assembly, and functions to amplify plant fitness

Microbial communities within seeds play a vital role in transmitting themselves to the next generation of plants. These microorganisms significantly impact seed vigor and early seedling growth, for successful crop establishment. Previous studies reported on seed-associated microbial communities and their influence on processes like dormancy release, germination, and disease protection. Modern sequencing and conventional methods reveal microbial community structures and environmental impacts, these information helps in microbial selection and manipulation. These studies form the foundation for using seed microbiomes to enhance crop resilience and productivity. While existing research has primarily focused on characterizing microbiota in dried mature seeds, a significant gap exists in understanding how these microbial communities assemble during seed development. The review also discusses applying seed-associated microorganisms to improve crops in the context of climate change. However, limited knowledge is available about the microbial assembly pattern on seeds, and their impact on plant growth. The review provides insight into microbial composition, functions, and significance for plant health, particularly regarding growth promotion and pest control.

Antimicrobial resistance in multistate outbreaks of nontyphoidal Salmonella infections linked to animal contact-United States, 2015-2018

Animal contact is an established risk factor for nontyphoidal Salmonella infections and outbreaks. During 2015-2018, the U.S. Centers for Disease Control and Prevention (CDC) and other U.S. public health laboratories began implementing whole-genome sequencing (WGS) of Salmonella isolates. WGS was used to supplement the traditional methods of pulsed-field gel electrophoresis for isolate subtyping, outbreak detection, and antimicrobial susceptibility testing (AST) for the detection of resistance. We characterized the epidemiology and antimicrobial resistance (AMR) of multistate salmonellosis outbreaks linked to animal contact during this time period. An isolate was considered resistant if AST yielded a resistant (or intermediate, for ciprofloxacin) interpretation to any antimicrobial tested by the CDC or if WGS showed a resistance determinant in its genome for one of these agents. We identified 31 outbreaks linked to contact with poultry (n = 23), reptiles (n = 6), dairy calves (n = 1), and guinea pigs (n = 1). Of the 26 outbreaks with resistance data available, we identified antimicrobial resistance in at least one isolate from 20 outbreaks (77%). Of 1,309 isolates with resistance information, 247 (19%) were resistant to ≥1 antimicrobial, and 134 (10%) were multidrug-resistant to antimicrobials from ≥3 antimicrobial classes. The use of resistance data predicted from WGS increased the number of isolates with resistance information available fivefold compared with AST, and 28 of 43 total resistance patterns were identified exclusively by WGS; concordance was high (>99%) for resistance determined by AST and WGS. The use of predicted resistance from WGS enhanced the characterization of the resistance profiles of outbreaks linked to animal contact by providing resistance information for more isolates.

The pangenome analysis of the environmental source Salmonella enterica highlights a diverse accessory genome and a distinct serotype clustering

Salmonella remains the leading cause of foodborne infections globally. Environmental reservoirs, particularly aquatic bodies, serve as conduits for the fecal-oral transmission of this pathogen. While the gastrointestinal tract is traditionally considered the primary habitat of Salmonella, mounting evidence suggests the bacterium's capacity for survival in external environments. The application of advanced technological platforms, such as next-generation sequencing, facilitates a comprehensive analysis of Salmonella's genomic features. This study aims to characterize the genomic composition of Salmonella isolates from river water, contributing to a potential paradigm shift and advancing public health protection. A total of 25 river water samples were collected and processed, followed by microbiological isolation of Salmonella strains, which were then sequenced. Genomic characterization revealed adaptive mechanisms, including gene duplication. Furthermore, an open pangenome, predisposed to incorporating foreign genetic material, was identified. Notably, antibiotic resistance genes were found to be part of the core genome, challenging previous reports that placed them in the accessory genome.

The important lessons lurking in the history of meningococcal epidemiology

INTRODUCTION

The epidemiology of invasive meningococcal disease (IMD), a rare but potentially fatal illness, is typically described as unpredictable and subject to sporadic outbreaks.

AREAS COVERED

Meningococcal epidemiology and vaccine use during the last ~ 200 years are examined within the context of meningococcal characterization and classification to guide future IMD prevention efforts.

EXPERT OPINION

Historical and contemporary data highlight the dynamic nature of meningococcal epidemiology, with continued emergence of hyperinvasive clones and affected regions. Recent shifts include global increases in serogroup W disease, meningococcal antimicrobial resistance (AMR), and meningococcal urethritis; additionally, unvaccinated populations have experienced disease resurgences following lifting of COVID-19 restrictions. Despite these changes, a close analysis of meningococcal epidemiology indicates consistent dominance of serogroups A, B, C, W, and Y and elevated IMD rates among infants and young children, adolescents/young adults, and older adults. Demonstrably effective vaccines against all 5 major disease-causing serogroups are available, and their prophylactic use represents a powerful weapon against IMD, including AMR. The World Health Organization's goal of defeating meningitis by the year 2030 demands broad protection against IMD, which in turn indicates an urgent need to expand meningococcal vaccination programs across major disease-causing serogroups and age-related risk groups.

Advanced design and applications of digital microfluidics in biomedical fields: An update of recent progress

Significant breakthroughs have been made in digital microfluidic (DMF)-based technologies over the past decades. DMF technology has attracted great interest in bioassays depending on automatic microscale liquid manipulations and complicated multi-step processing. In this review, the recent advances of DMF platforms in the biomedical field were summarized, focusing on the integrated design and applications of the DMF system. Firstly, the electrowetting-on-dielectric principle, fabrication of DMF chips, and commercialization of the DMF system were elaborated. Then, the updated droplets and magnetic beads manipulation strategies with DMF were explored. DMF-based biomedical applications were comprehensively discussed, including automated sample preparation strategies, immunoassays, molecular diagnosis, blood processing/testing, and microbe analysis. Emerging applications such as enzyme activity assessment and DNA storage were also explored. The performance of each bioassay was compared and discussed, providing insight into the novel design and applications of the DMF technology. Finally, the advantages, challenges, and future trends of DMF systems were systematically summarized, demonstrating new perspectives on the extensive applications of DMF in basic research and commercialization.

Rapid identification of enteric bacteria from whole genome sequences using average nucleotide identity metrics

Identification of enteric bacteria species by whole genome sequence (WGS) analysis requires a rapid and an easily standardized approach. We leveraged the principles of average nucleotide identity using MUMmer (ANIm) software, which calculates the percent bases aligned between two bacterial genomes and their corresponding ANI values, to set threshold values for determining species consistent with the conventional identification methods of known species. The performance of species identification was evaluated using two datasets: the Reference Genome Dataset v2 (RGDv2), consisting of 43 enteric genome assemblies representing 32 species, and the Test Genome Dataset (TGDv1), comprising 454 genome assemblies which is designed to represent all species needed to query for identification, as well as rare and closely related species. The RGDv2 contains six Campylobacter spp., three Escherichia/Shigella spp., one Grimontia hollisae, six Listeria spp., one Photobacterium damselae, two Salmonella spp., and thirteen Vibrio spp., while the TGDv1 contains 454 enteric bacterial genomes representing 42 different species. The analysis showed that, when a standard minimum of 70% genome bases alignment existed, the ANI threshold values determined for these species were ≥95 for Escherichia/Shigella and Vibrio species, ≥93% for Salmonella species, and ≥92% for Campylobacter and Listeria species. Using these metrics, the RGDv2 accurately classified all validation strains in TGDv1 at the species level, which is consistent with the classification based on previous gold standard methods.

Effectiveness of Self-Collected, Ambient Temperature-Preserved Nasal Swabs Compared to Samples Collected by Trained Staff for Genotyping of Respiratory Viruses by Shotgun RNA Sequencing: Comparative Study

BACKGROUND

The SARS-CoV-2 pandemic has underscored the need for field specimen collection and transport to diagnostic and public health laboratories. Self-collected nasal swabs transported without dependency on a cold chain have the potential to remove critical barriers to testing, expand testing capacity, and reduce opportunities for exposure of health professionals in the context of a pandemic.

OBJECTIVE

We compared nasal swab collection by study participants from themselves and their children at home to collection by trained research staff.

METHODS

Each adult participant collected 1 nasal swab, sampling both nares with the single swab, after which they collected 1 nasal swab from 1 child. After all the participant samples were collected for the household, the research staff member collected a separate single duplicate sample from each individual. Immediately after the sample collection, the adult participants completed a questionnaire about the acceptability of the sampling procedures. Swabs were placed in temperature-stable preservative and respiratory viruses were detected by shotgun RNA sequencing, enabling viral genome analysis.

RESULTS

In total, 21 households participated in the study, each with 1 adult and 1 child, yielding 42 individuals with paired samples. Study participants reported that self-collection was acceptable. Agreement between identified respiratory viruses in both swabs by RNA sequencing demonstrated that adequate collection technique was achieved by brief instructions.

CONCLUSIONS

Our results support the feasibility of a scalable and convenient means for the identification of respiratory viruses and implementation in pandemic preparedness for novel respiratory pathogens.

Applications of genome-scale metabolic models to investigate microbial metabolic adaptations in response to genetic or environmental perturbations

Environmental perturbations are encountered by microorganisms regularly and will require metabolic adaptations to ensure an organism can survive in the newly presenting conditions. In order to study the mechanisms of metabolic adaptation in such conditions, various experimental and computational approaches have been used. Genome-scale metabolic models (GEMs) are one of the most powerful approaches to study metabolism, providing a platform to study the systems level adaptations of an organism to different environments which could otherwise be infeasible experimentally. In this review, we are describing the application of GEMs in understanding how microbes reprogram their metabolic system as a result of environmental variation. In particular, we provide the details of metabolic model reconstruction approaches, various algorithms and tools for model simulation, consequences of genetic perturbations, integration of '-omics' datasets for creating context-specific models and their application in studying metabolic adaptation due to the change in environmental conditions.

Role of circulating biomarkers in spinal muscular atrophy: insights from a new treatment era

Spinal muscular atrophy (SMA) is a lower motor neuron disease due to biallelic mutations in the SMN1 gene on chromosome 5. It is characterized by progressive muscle weakness of limbs, bulbar and respiratory muscles. The disease is usually classified in four different phenotypes (1-4) according to age at symptoms onset and maximal motor milestones achieved. Recently, three disease modifying treatments have received approval from the Food and Drug Administration (FDA) and the European Medicines Agency (EMA), while several other innovative drugs are under study. New therapies have been game changing, improving survival and life quality for SMA patients. However, they have also intensified the need for accurate biomarkers to monitor disease progression and treatment efficacy. While clinical and neurophysiological biomarkers are well established and helpful in describing disease progression, there is a great need to develop more robust and sensitive circulating biomarkers, such as proteins, nucleic acids, and other small molecules. Used alone or in combination with clinical biomarkers, they will play a critical role in enhancing patients' stratification for clinical trials and access to approved treatments, as well as in tracking response to therapy, paving the way to the development of individualized therapeutic approaches. In this comprehensive review, we describe the foremost circulating biomarkers of current significance, analyzing existing literature on non-treated and treated patients with a special focus on neurofilaments and circulating miRNA, aiming to identify and examine their role in the follow-up of patients treated with innovative treatments, including gene therapy.

Performance of targeted next-generation sequencing in the detection of respiratory pathogens and antimicrobial resistance genes for children

Introduction. Respiratory tract infection, which is associated with high morbidity and mortality, occurs frequently in children. At present, the main diagnostic method is culture. However, the low pathogen detection rate of the culture approach prevents timely and accurate diagnosis. Fortunately, next-generation sequencing (NGS) can compensate for the deficiency of culture, and its application in clinical diagnostics has become increasingly available.Gap Statement. Targeted NGS (tNGS) is a platform that can select and enrich specific regions before data enter the NGS pipeline. However, the performance of tNGS in the detection of respiratory pathogens and antimicrobial resistance genes (ARGs) in infections in children is unclear.Aim and methodology. In this study, we estimated the performance of tNGS in the detection of respiratory pathogens and ARGs in 47 bronchoalveolar lavage fluid (BALF) specimens from children using conventional culture and antimicrobial susceptibility testing (AST) as the gold standard.Results. RPIP (Respiratory Pathogen ID/AMR enrichment) sequencing generated almost 500 000 reads for each specimen. In the detection of pathogens, RPIP sequencing showed targeted superiority in detecting difficult-to-culture bacteria, including Mycoplasma pneumoniae. Compared with the results of culture, the sensitivity and specificity of RPIP were 84.4 % (confidence interval 70.5-93.5 %) and 97.7 % (95.9 -98.8%), respectively. Moreover, RPIP results showed that a single infection was detected in 10 of the 47 BALF specimens, and multiple infections were detected in 34, with the largest number of bacterial/viral coinfections. Nevertheless, there were also three specimens where no pathogen was detected. Furthermore, we analysed the drug resistance genes of specimens containing Streptococcus pneumoniae, which was detected in 25 out of 47 specimens in the study. A total of 58 ARGs associated with tetracycline, macrolide-lincosamide-streptogramin, beta-lactams, sulfonamide and aminoglycosides were identified by RPIP in 19 of 25 patients. Using the results of AST as a standard, the coincidence rates of erythromycin, tetracycline, penicillin and sulfonamides were 89.5, 79.0, 36.8 and 42.1 %, respectively.Conclusion. These results demonstrated the superiority of RPIP in pathogen detection, particularly for multiple and difficult-to-culture pathogens, as well as in predicting resistance to erythromycin and tetracycline, which has significance for the accurate diagnosis of pathogenic infection and in the guidance of clinical treatment.

Introduction and benchmarking of pyMLST: open-source software for assessing bacterial clonality using core genome MLST

Core genome multilocus sequence typing (cgMLST) has gained in popularity for bacterial typing since whole-genome sequencing (WGS) has become affordable. We introduce here pyMLST, a new complete, stand-alone, free and open source pipeline for cgMLST analysis. pyMLST can create or import a core genome database. For each gene, the first allele is aligned against the bacterial genome of interest using BLAT. Incomplete genes are aligned using MAFT. All data are stored in a SQLite database. pyMLST accepts assembly genomes or raw data (with the option pyMLST-KMA) as input. To evaluate our new tool, we selected three genome collections of major bacterial pathogens (Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus) and compared them with pyMLST, pyMLST-KMA, ChewBBACA, SeqSphere and the variant calling approach. We compared the sensitivity, precision and false-positive rate for each method with those of the variant calling approach. Minimal spanning trees were generated with each type of software to evaluate their interest in the context of a bacterial outbreak. We found that pyMLST-KMA is a convenient screening method to avoid assembling large bacterial collections. Our data showed that pyMLST (free, open source, available in Galaxy and pipeline ready) performed similarly to the commercial SeqSphere and performed better than ChewBBACA and pyMLST-KMA.

Legionella pneumophila exploits the endo-lysosomal network for phagosome biogenesis by co-opting SUMOylated Rab7

L. pneumophila strains harboring wild-type rpsL such as Lp02rpsLWT cannot replicate in mouse bone marrow-derived macrophages (BMDMs) due to induction of extensive lysosome damage and apoptosis. The mechanism of this unique infection-induced cell death remains unknown. Using a genome-wide CRISPR/Cas9 screening, we identified Hmg20a and Nol9 as host factors important for restricting strain Lp02rpsLWT in BMDMs. Depletion of Hmg20a protects macrophages from infection-induced lysosomal damage and apoptosis, allowing productive bacterial replication. The restriction imposed by Hmg20a was mediated by repressing the expression of several endo-lysosomal proteins, including the small GTPase Rab7. We found that SUMOylated Rab7 is recruited to the bacterial phagosome via SulF, a Dot/Icm effector that harbors a SUMO-interacting motif (SIM). Moreover, overexpression of Rab7 rescues intracellular growth of strain Lp02rpsLWT in BMDMs. Our results establish that L. pneumophila exploits the lysosomal network for the biogenesis of its phagosome in BMDMs.

Current Uses and Future Perspectives of Genomic Technologies in Clinical Microbiology

Recent advancements in sequencing technology and data analytics have led to a transformative era in pathogen detection and typing. These developments not only expedite the process, but also render it more cost-effective. Genomic analyses of infectious diseases are swiftly becoming the standard for pathogen analysis and control. Additionally, national surveillance systems can derive substantial benefits from genomic data, as they offer profound insights into pathogen epidemiology and the emergence of antimicrobial-resistant strains. Antimicrobial resistance (AMR) is a pressing global public health issue. While clinical laboratories have traditionally relied on culture-based antimicrobial susceptibility testing, the integration of genomic data into AMR analysis holds immense promise. Genomic-based AMR data can furnish swift, consistent, and highly accurate predictions of resistance phenotypes for specific strains or populations, all while contributing invaluable insights for surveillance. Moreover, genome sequencing assumes a pivotal role in the investigation of hospital outbreaks. It aids in the identification of infection sources, unveils genetic connections among isolates, and informs strategies for infection control. The One Health initiative, with its focus on the intricate interconnectedness of humans, animals, and the environment, seeks to develop comprehensive approaches for disease surveillance, control, and prevention. When integrated with epidemiological data from surveillance systems, genomic data can forecast the expansion of bacterial populations and species transmissions. Consequently, this provides profound insights into the evolution and genetic relationships of AMR in pathogens, hosts, and the environment.

A Comprehensive Bioinformatics Resource Guide for Genome-Based Antimicrobial Resistance Studies

The use of high-throughput sequencing technologies and bioinformatic tools has greatly transformed microbial genome research. With the help of sophisticated computational tools, it has become easier to perform whole genome assembly, identify and compare different species based on their genomes, and predict the presence of genes responsible for proteins, antimicrobial resistance, and toxins. These bioinformatics resources are likely to continuously improve in quality, become more user-friendly to analyze the multiple genomic data, efficient in generating information and translating it into meaningful knowledge, and enhance our understanding of the genetic mechanism of AMR. In this manuscript, we provide an essential guide for selecting the popular resources for microbial research, such as genome assembly and annotation, antibiotic resistance gene profiling, identification of virulence factors, and drug interaction studies. In addition, we discuss the best practices in computer-oriented microbial genome research, emerging trends in microbial genomic data analysis, integration of multi-omics data, the appropriate use of machine-learning algorithms, and open-source bioinformatics resources for genome data analytics.

Heterogeneity and transmission of food safety-related enterotoxigenic Staphylococcus aureus in pig abattoirs in Hubei, China

The dissemination of Staphylococcus aureus in the pork production chain is a major food safety concern. Abattoirs can serve both as disruptor and transmitter for S. aureus. In this study, we conducted a systematic genomic epidemiology research on the prevalence, heterogeneity, and transmission of S. aureus in 3,638 samples collected from four pig abattoirs in Hubei province, China. Our findings revealed substantial heterogeneity between S. aureus recovered from samples collected at upstream (from stunning step to head-removal step) and downstream (from splitting step to chilling step) locations within the slaughter process. Overall, 966 (26.6%) samples were positive for S. aureus, with significantly higher overall prevalence for upstream samples (29.0%, 488/1,681) compared to downstream samples (24.4%, 478/1,957). Antimicrobial susceptibility testing demonstrated that the isolates from the upstream exhibited significantly higher resistance proportions to different antimicrobials than those from the downstream. Whole-genome sequencing of 126 isolates revealed that ST398 (32.9%, 23/70) and ST9 (22.9%, 16/70) were more common among upstream isolates, while ST7 (35.7%, 20/56) and ST97 (28.6%, 16/56) were most frequently observed among downstream isolates. Additionally, molecular characterization analysis demonstrated that upstream isolates possessed significantly higher enterotoxigenic potential, more antimicrobial resistance genes, and S. aureus pathogenicity islands than downstream isolates. Notably, we discovered that enterotoxigenic S. aureus could be transmitted across different slaughter stages, with knives, water, and air serving as vectors. Although slaughtering processes had a substantial effect on reducing the food safety risk posed by enterotoxigenic S. aureus, the possibility of its widespread transmission should not be disregarded. IMPORTANCE Staphylococcus aureus (S. aureus) is one of the most important foodborne pathogens, and can cause foodborne poisoning by producing enterotoxins. Pork is a preferable reservoir and its contamination often occurs during the slaughter process. Our findings revealed significant differences in the prevalence, antimicrobial resistance, and enterotoxigenic potential between the upstream and downstream isolates within the slaughter process. Also, it is imperative not to overlook enterotoxigenic S. aureus transmitted across all stages of the slaughter process, with notable vectors being knives, water, and air. These findings hold significant implications for policy-makers to reassess their surveillance projects, and underscore the importance of implementing effective control measures to minimize the risk of S. aureus contamination in pork production. Moreover, we provide a more compelling method of characterizing pathogen transmission based on core-SNPs of bacterial genomes.

Micro- and nanosystems for the detection of hemorrhagic fever viruses

Hemorrhagic fever viruses (HFVs) are virulent pathogens that can cause severe and often fatal illnesses in humans. Timely and accurate detection of HFVs is critical for effective disease management and prevention. In recent years, micro- and nano-technologies have emerged as promising approaches for the detection of HFVs. This paper provides an overview of the current state-of-the-art systems for micro- and nano-scale approaches to detect HFVs. It covers various aspects of these technologies, including the principles behind their sensing assays, as well as the different types of diagnostic strategies that have been developed. This paper also explores future possibilities of employing micro- and nano-systems for the development of HFV diagnostic tools that meet the practical demands of clinical settings.

Evaluation of whole and core genome multilocus sequence typing allele schemes for Salmonella enterica outbreak detection in a national surveillance network, PulseNet USA

Salmonella enterica is a leading cause of bacterial foodborne and zoonotic illnesses in the United States. For this study, we applied four different whole genome sequencing (WGS)-based subtyping methods: high quality single-nucleotide polymorphism (hqSNP) analysis, whole genome multilocus sequence typing using either all loci [wgMLST (all loci)] and only chromosome-associated loci [wgMLST (chrom)], and core genome multilocus sequence typing (cgMLST) to a dataset of isolate sequences from 9 well-characterized Salmonella outbreaks. For each outbreak, we evaluated the genomic and epidemiologic concordance between hqSNP and allele-based methods. We first compared pairwise genomic differences using all four methods. We observed discrepancies in allele difference ranges when using wgMLST (all loci), likely caused by inflated genetic variation due to loci found on plasmids and/or other mobile genetic elements in the accessory genome. Therefore, we excluded wgMLST (all loci) results from any further comparisons in the study. Then, we created linear regression models and phylogenetic tanglegrams using the remaining three methods. K-means analysis using the silhouette method was applied to compare the ability of the three methods to partition outbreak and sporadic isolate sequences. Our results showed that pairwise hqSNP differences had high concordance with cgMLST and wgMLST (chrom) allele differences. The slopes of the regressions for hqSNP vs. allele pairwise differences were 0.58 (cgMLST) and 0.74 [wgMLST (chrom)], and the slope of the regression was 0.77 for cgMLST vs. wgMLST (chrom) pairwise differences. Tanglegrams showed high clustering concordance between methods using two statistical measures, the Baker's gamma index (BGI) and cophenetic correlation coefficient (CCC), where 9/9 (100%) of outbreaks yielded BGI values ≥ 0.60 and CCCs were ≥ 0.97 across all nine outbreaks and all three methods. K-means analysis showed separation of outbreak and sporadic isolate groups with average silhouette widths ≥ 0.87 for outbreak groups and ≥ 0.16 for sporadic groups. This study demonstrates that Salmonella isolates clustered in concordance with epidemiologic data using three WGS-based subtyping methods and supports using cgMLST as the primary method for national surveillance of Salmonella outbreak clusters.