Background: Blood cultures are essential for diagnosing bloodstream infections, but current phenotypic tests for antimicrobial resistance (AMR) provide limited information. Oxford Nanopore Technologies introduces nanopore sequencing with adaptive sampling, capable of real-time host genome depletion, yet its application directly from blood cultures remains unexplored. This study aimed to identify pathogens and predict AMR using nanopore sequencing. Methods: In this cross-sectional genomic study, 458 positive blood cultures from bloodstream infection patients in central Taiwan were analyzed. Parallel experiments involved routine microbiologic tests and nanopore sequencing with a 15-h run. A bioinformatic pipeline was proposed to analyze the real-time sequencing reads. Subsequently, a comparative analysis was performed to evaluate the performance of species identification and AMR prediction. Results: The pipeline identified 76 species, with 88 Escherichia coli, 74 Klebsiella pneumoniae, 43 Staphylococcus aureus, and 9 Candida samples. Novel species were also discovered. Notably, precise species identification was achieved not only for monomicrobial infections but also for polymicrobial infections, which was detected in 23 samples and further confirmed by full-length 16S rRNA amplicon sequencing. Using a modified ResFinder database, AMR predictions showed a categorical agreement rate exceeding 90% (3799/4195) for monomicrobial infections, with minimal very major errors observed for K. pneumoniae (2/186, 1.1%) and S. aureus (1/90, 1.1%). Conclusions: Nanopore sequencing with adaptive sampling can directly analyze positive blood cultures, facilitating pathogen detection, AMR prediction, and outbreak investigation. Integrating nanopore sequencing into clinical practices signifies a revolutionary advancement in managing bloodstream infections, offering an effective antimicrobial stewardship strategy, and improving patient outcomes.

We aimed to determine susceptibilities of Elizabethkingia spp. to 25 commonly tested and 8 novel antibiotics, and to compare the performance of different susceptibility testing methods. Clinical isolates of Elizabethkingia spp., Chryseobacterium spp. and Flavobacterium spp. collected during 2002–18 (n = 210) in a nationwide surveillance programme in Taiwan were speciated by 16S rRNA sequencing. MICs were determined by broth microdilution. The broth microdilution results of 18 common antibiotics were compared with those obtained by the VITEK 2 automated system. Among the Elizabethkingia spp. identified (n = 108), Elizabethkingia anophelis was the most prevalent (n = 90), followed by Elizabethkingia meningoseptica (n = 7) and Elizabethkingia miricola cluster [E. miricola (n = 6), Elizabethkingia bruuniana (n = 3) and Elizabethkingia ursingii (n = 2)]. Most isolates were recovered from respiratory or blood specimens from hospitalized, elderly patients. PFGE showed two major and several minor E. anophelis clones. All isolates were resistant to nearly all the tested β-lactams. Doxycycline, minocycline and trimethoprim/sulfamethoxazole inhibited >90% of Elizabethkingia spp. Rifampin inhibited E. meningoseptica (100%) and E. anophelis (81.1%). Fluoroquinolones and tigecycline were active against E. meningoseptica and E. miricola cluster isolates. Novel antibiotics, including imipenem/relebactam, meropenem/vaborbactam, ceftazidime/avibactam, cefepime/zidebactam, delafloxacin, eravacycline and omadacycline were ineffective but lascufloxacin inhibited half of Elizabethkingia spp. The very major discrepancy rates of VITEK 2 were >1.5% for ciprofloxacin, moxifloxacin and vancomycin. Major discrepancy rates were >3% for amikacin, tigecycline, piperacillin/tazobactam and trimethoprim/sulfamethoxazole. MDR, absence of standard interpretation criteria and poor intermethod concordance necessitate working guidelines to facilitate future research of emerging Elizabethkingia spp.

Multilocus sequence typing (MLST) is one of the most commonly used methods for studying microbial lineage worldwide. However, the traditional MLST process using Sanger sequencing is time-consuming and expensive. We have designed a workflow that simultaneously sequenced seven full-length housekeeping genes of 96 meticillin-resistant Staphylococcus aureus isolates with dual-barcode multiplexing using just a single flow cell of an Oxford Nanopore Technologies MinION system, and then we performed bioinformatic analysis for strain typing. Fifty-one of the isolates comprising 34 sequence types had been characterized using Sanger sequencing. We demonstrate that the allele assignments obtained by our nanopore workflow (nanoMLST, available at https://github.com/jade-nhri/nanoMLST) were identical to those obtained by Sanger sequencing (359/359, with 100 % agreement rate). In addition, we estimate that our multiplex system is able to perform MLST for up to 1000 samples simultaneously; thus, providing a rapid and cost-effective solution for molecular typing.

Elizabethkingia anophelis is inherently resistant to multiple antibiotics, except minocycline. This study aimed to determine the in vitro and in vivo efficacy of minocycline monotherapy and combination therapy against susceptible strains and the impact of reduced minocycline susceptibility. Three clinical isolates and one laboratory-induced mutant with reduced minocycline susceptibility were included. Time-kill and checkerboard assays were used to assess in vitro efficacy and synergy, respectively. Galleria mellonella infection and mouse pneumonia models were used to assess in vivo efficacy, and a mouse thigh infection model was used to determine the bacterial load. Minocycline monotherapy exerted a modest inhibitory effect on three clinical minocycline-susceptible E. anophelis isolates in vitro, but delayed G. mellonella death and improved infected mouse survival; it also significantly reduced the in vivo bacterial load. Minocycline had decreased efficacy on G. mellonella and mice infected by the mutant with reduced minocycline susceptibility. Genome comparison revealed several spontaneous mutations associated with reduced minocycline susceptibility. Among eight antibiotics tested in combination with minocycline, rifampin consistently showed in vitro synergy. The addition of rifampin (1 mg/L) reduced the mutant prevention concentration of minocycline from 2-4 mg/L to < 0.5 mg/L. However, compared with monotherapy, the combination of rifampin and minocycline did not further reduce the bacterial load or improve the survival of G. mellonella or mice. Minocycline monotherapy was in vivo effective against susceptible E. anophelis. Reduced minocycline susceptibility due to spontaneous mutation decreased its therapeutic efficacy. In combination with rifampin, it prevented the in vitro emergence of reduced susceptibility but did not provide additional in vivo survival benefit.

Recent advances in whole-genome sequencing (WGS) have increased the accessibility of this tool, offering substantial potential for pathogen surveillance, outbreak response, and diagnostics. However, the routine clinical adoption of WGS is hindered by factors such as high costs, technical complexity, and the requirement for bioinformatics expertise for data analysis. To address these challenges, we propose RapidONT, a workflow designed for cost-effective and accessible WGS-based pathogen analysis. RapidONT employs a mechanical shearing–based DNA extraction protocol, followed by library construction by using a multiplexing Oxford nanopore technologies (ONT) rapid barcoding kit. Flye software is used for de novo assembly without manual intervention, followed by basic assembly polishing using Medaka and Homopolish. The polished assemblies are then analyzed using the user-friendly web-based platform Pathogenwatch, which facilitates species identification, molecular typing, and antimicrobial resistance (AMR) prediction, all while requiring minimal bioinformatics expertise. The efficacy of RapidONT was evaluated using nine clinically relevant pathogens, encompassing a total of 90 gram-positive and gram-negative bacterial strains. The workflow demonstrated high accuracy in critical tasks such as multilocus sequence typing (MLST) and AMR identification, using only ONT R9.4.1 flowcell data. Notably, limitations were observed with Salmonella spp. and Neisseria gonorrhoeae. Furthermore, RapidONT enabled the generation of genomic information for 48 bacterial isolates by using a single flow cell, significantly reducing sequencing costs. This approach eliminates the need for extensive experimentation in obtaining crucial genomic information. This workflow facilitates broader WGS implementation in clinical pathogen analysis and diagnostics.

For tiling of the SARS-CoV-2 genome, the ARTIC Network provided a V4 protocol using 99 pairs of primers for amplicon production and is currently the widely used amplicon-based approach. However, this technique has regions of low sequence coverage and is labour-, time-, and cost-intensive. Moreover, it requires 14 pairs of primers in two separate PCRs to obtain spike gene sequences. To overcome these disadvantages, we proposed a single PCR to efficiently detect spike gene mutations. We proposed a bioinformatic protocol that can process FASTQ reads into spike gene consensus sequences to accurately call spike protein variants from sequenced samples or to fairly express the cases of missing amplicons. We evaluated the in silico detection rate of primer sets that yield amplicon sizes of 400, 1200, and 2500 bp for spike gene sequencing of SARS-CoV-2 to be 59.49, 76.19, and 92.20%, respectively. The in silico detection rate of our proposed single PCR primers was 97.07%. We demonstrated the robustness of our analytical protocol against 3000 Oxford Nanopore sequencing runs of distinct datasets, thus ensuring high-integrity sequencing of spike genes for variant SARS-CoV-2 determination. Our protocol works well with the data yielded from versatile primer designs, making it easy to determine spike protein variants.