Bacterial bloodstream infections (BSI) form a large public health threat worldwide. Current routine diagnosis is based on blood culture (BC) but this technique suffers from limited sensitivity. Molecular diagnostic tools have been developed for identification of bacteria in the blood of BSI patients. 16S metagenomics is an open-ended technique that can detect simultaneously all bacteria in a given sample based on PCR amplification of the 16S ribosomal RNA gene (rDNA) followed by sequencing of the PCR amplicons and taxonomic labeling of the sequence reads at genus or species level. Areas covered: Here we review the studies that have used 16S metagenomics for the identification of bacteria in human blood samples. We also discuss the potential added value of 16S metagenomics in the diagnosis of BSI, challenges as well as future directions for implementation in clinical settings. Expert commentary: 16S metagenomics has the potential to complement conventional BC; however, the technique currently suffers from several technical limitations jeopardizing implementation in routine clinical microbiology laboratories. Further studies are required to assess the cost-efficiency and clinical impact of 16S metagenomics in comparison to BC which remains the gold standard diagnostic method for BSI.

Bacterial bloodstream infection (bBSI) represents any form of invasiveness of the blood circulatory system caused by bacteria and can lead to death among critically ill patients. Thus, there is a need for rapid and accurate diagnosis and treatment of patients with septicemia. So far, different molecular diagnostic tools have been developed. The majority of these tools focus on amplification based techniques such as polymerase chain reaction (PCR) which allows the detection of nucleic acids (both DNA and small RNAs) that are specific to bacterial species and sequencing or nucleic acid hybridization that allows the detection of bacteria in order to reduce delay of appropriate antibiotic therapy. However, there is still a need to improve sensitivity of most molecular techniques to enhance their accuracy and allow exact and on time antibiotic therapy treatment. In this regard, we conducted a systematic review of the existing studies conducted in molecular diagnosis of bBSIs, with the main aim of reporting on clinical significance and benefits of molecular diagnosis to patients. We searched both Google Scholar and PubMed. In total, eighteen reviewed papers indicate that shift from conventional diagnostic methods to molecular tools is needed and would lead to accurate diagnosis and treatment of bBSI.

The Global Typhoid Genomics Consortium was established to bring together the typhoid research community to aggregate and analyseSalmonella entericaserovar Typhi (Typhi) genomic data to inform public health action. This analysis, which marks twenty-one years since the publication of the first Typhi genome, represents the largest Typhi genome sequence collection to date (n=13,000), and provides a detailed overview of global genotype and antimicrobial resistance (AMR) distribution and temporal trends, generated using open analysis platforms (GenoTyphi and Pathogenwatch). Compared with previous global snapshots, the data highlight that genotype 4.3.1 (H58) has not spread beyond Asia and Eastern/Southern Africa; in other regions, distinct genotypes dominate and have independently evolved AMR. Data gaps remain in many parts of the world, and we show potential of travel-associated data to provide informal ″sentinel″ surveillance for such locations. The data indicate ciprofloxacin non-susceptibility (> 1 resistance determinant) is widespread across geographies and genotypes, with high-level resistance (≥3 determinants) reaching 20% prevalence in South Asia. Extensively drug-resistant (XDR) typhoid has become dominant in Pakistan (70% in 2020), but has not yet become established elsewhere. Ceftriaxone resistance has emerged in eight non-XDR genotypes, including a ciprofloxacin-resistant lineage (4.3.1.2.1) in India. Azithromycin resistance mutations were detected at low prevalence in South Asia, including in two common ciprofloxacin-resistant genotypes. The Consortium's aim is to encourage continued data sharing and collaboration to monitor the emergence and global spread of AMR Typhi, and to inform decision-making around the introduction of typhoid conjugate vaccines (TCVs) and other prevention and control strategies.