Obligate anaerobes are abundant in human necrotizing soft tissue infection samples – a metagenomics analysis

Abstract

Necrotizing soft tissue infections (NSTIs) are associated with high morbidity and mortality and are increasing in incidence. Proper identification of the microbial causes of NSTIs is a crucial step in diagnosis and treatment, but the majority of data collected are culture based, which is biased against fastidious organisms, including obligate anaerobes. The goal of this study was to address this gap in knowledge by characterizing NSTI microbial communities through molecular diagnostics. We performed 16S rRNA sequencing on human NSTI samples and identified five genera most commonly found in NSTIs (Prevotella, Bacteroides, Peptoniphilus, Porphyromonas, and Enterococcus). We found that a >70% contribution of obligate anaerobes to the bacterial population distribution was associated with NSTI mortality, and that NSTI samples, from both survivors and non‐survivors, had an increased relative abundance of gram negative bacteria compared to those of abscess patients. Based on our data, we conclude that obligate anaerobes are abundant in NSTIs and a high relative abundance of anaerobes is associated with a worse outcome. We recommend increasing anaerobe antibiotic coverage during the treatment of NSTIs even when anaerobes are not found by traditional clinical microbiology methods, and especially when there is a clinical suspicion for anaerobe involvement.

Obesity Is Not an Independent Predictor of Necrotizing Soft Tissue Infection Outcomes

“…They can be further divided by tissue layer, such as necrotizing fasciitis when involving fascia or myositis when involving muscle, or by anatomic location, such as Fournier gangrene when present in the genitalia and perineum [1][2][3][4]. These infections are polymicrobial up to 80% of the time, with a predominance of group A Streptococcus (GAS), Staphylococcus aureus, Enterococcus, and multiple anaerobic bacterial species [2,[5][6][7].…”

Necrotizing Soft Tissue Infection After Intravenous Drug Injection: A Multidisciplinary Approach to Surgical Management at a Community Hospital

“…2 Prevotella denticola is an anaerobic gramnegative bacterium that is usually found in periodontal abscesses and head and neck necrotizing fasciitis. 3 These bacteria were sensitive to his antibiotic regimen, and repeat tissue cultures from serial wound debridement showed no bacteria growth. Therefore, antibiotics were not indicated at discharge, and plastic surgery was able to close the large wound defect.…”

Clinical Implications of Polymicrobial Synergism Effects on Antimicrobial Susceptibility

“…It was recently shown that necrotizing soft tissue infections (NSTIs), infamous for their high patient morbidity and mortality, contain several species of anaerobes, many of which are difficult to culture. Furthermore, 16s rRNA sequencing revealed a more diverse bacterial community than attempts at culturing displayed [ 8 ]. Bessa et al collected samples from 217 chronically infected wounds which showed infections from 28 different species of bacteria.…”