Anaerobic Infections: 2017

Infections caused by anaerobic bacteria are common, and may be serious and life-threatening. Anaerobes predominant in the bacterial flora of normal human skin and mucous membranes, and are a common cause of bacterial infections of endogenous origin. Infections due to anaerobes can evolve all body systems and sites. The predominate ones include: abdominal, pelvic, respiratory, and skin and soft tissues infections. Because of their fastidious nature, they are difficult to isolate and are often overlooked. Failure to direct therapy against these organisms often leads to clinical failures. Their isolation requires appropriate methods of collection, transportation and cultivation of specimens. Treatment of anaerobic bacterial infection is complicated by the slow growth of these organisms, which makes diagnosis in the laboratory only possible after several days, by their often polymicrobial nature and by the growing resistance of anaerobic bacteria to antimicrobial agents.

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Monday, December 25, 2017

Establishing the bacterial etiology of necrotizing soft tissue infections using 16S sequencing detection

Necrotizing soft tissue infections (NSTIs) are the most severe and rapidly progressing class of skin and soft tissue infections (SSTIs). They are a surgical emergency and are associated with high mortality and morbidity. While NSTIs remain relatively rare, their incidence is steadily rising.

Earlier diagnosis and more focused antibiotic treatments can potentially improve patient outcome, but both of these solutions require a more accurate understanding of the microbial component of these infections.

Streptococcus and Staphylococcus species, especially S. aureus, are most commonly aerobic isolates and Clostridium spp. (C.perfringens and C. septicum) and Bacteroides fragilis group are the commonest anaerobes detected. Clostridium spp. are often found in monomicrobial infections and are associated with mortality rates greater than 50%. Certain gram negative rods, including Escherichia coli and Pseudomonas species, are also found,

While molecular detection methods, namely 16S sequencing, have not been traditionally used to identify the causative microorganisms in NSTIs, they are becoming more commonplace as a diagnostic tool for other types of SSTIs, especially for chronic wound infections. In chronic wound infections, 16S sequencing has revealed a higher than previously detected prevalence of obligate anaerobes. The use of 16S sequencing may lead to the detection of a higher than expected proportion of obligate anaerobes in NSTIs and consequently improve the care of patients with NSTIs.

Necrotizing fasciitis