Next-generation sequencing technology for the diagnosis of microbial infections in hard-to-heal wounds

A hard-to-heal wound does not usually progress through the normal wound repair process and remains in an inflammatory state. The aetiology of a hard-to-heal wound may be varied but they are generally recurrent in patients predisposed to certain conditions, including diabetes. Hard-to-heal wounds associated with diabetic foot ulcers are a significant cause of morbidity and mortality. Microbial infections further delay the healing process, contributing to its chronicity and influence the pathogenicity of infection-causing bacteria. Traditionally, culture-based methods have been employed to study microbial communities within the hard-to-heal wound. This method underestimates or excludes most of the dominant species and is oversensitive towards others. These limitations in the culture-based methods can be overcome by advanced molecular technologies, such as next-generation sequencing (NGS), which has significantly broadened our view of the wound-associated microbiome. Sequencing of genes coding for small subunit ribosomal RNA and internal transcribed spacer locus for identification of bacteria and fungi, respectively, has provided more quantitative data in a faster, more cost-effective manner and has resulted in better microbial characterisation of wounds. In this review, we have examined in detail the NGS-based molecular characterisation of wound-associated microbes and its impact on modalities for effective treatment of hard-to-heal wound ulcers. The aim of the review was to highlight the advantages and disadvantages associated with traditional and advanced molecular technologies, such as NGS, to study the wound-associated microbiome. A full understanding of the complete diversity of the wound microbiome will help in devising effective treatment regimens for hard-to-heal wounds.