The Conundrum of the Gram-Positive Rod: Are We Missing Important Pathogens in Complicated Skin and Soft-Tissue Infections? A Case Report and Review of the Literature

Abstract

At our facility, diphtheroids are generally considered non-pathogenic contaminants in skin and soft tissue infections. The finding of A. bernardiae in necrotizing fasciitis is unusual and clinically important but would have been missed using conventional methods. As the "gram-positive bacillus" comes to include an ever-increasing number of organisms, genetic sequencing will probably be required more regularly for species identification. Furthermore, given that these genera are similar, often mistaken as contaminants, and difficult to differentiate using standard assays, they may often be missed and are possibly a more-frequent cause of complicated skin and soft tissue infections than the literature would suggest.

A case of diabetic foot ulcers complicated by severe infection and sepsis with Trueperella bernardiae

“…In general, patients have severe comorbidities, co-infections with other bacteria are often observed and the infections progress slowly. In the most severe case reported to date, T. bernardiae together with Morganella morganii were isolated from an abdominal necrotizing fasciitis in the lower left abdominal quadrant in a patient with several co-morbidities including advanced diabetic mellitus type II, morbid obesity and chronic obstructive pulmonary disease (Clarke et al, 2010). After several surgical debridements down to the necrotic fascia, the patient was left with a 30645 cm defect, which resolved.…”

“…bernardiae has been described as a pathogen in urinary tract infections (Ieven et al, 1996;Lepargnear et al, 1998), joint infections (Adderson et al, 1998;Bemer et al, 2009;Lo ez et al, 2009), skin and soft-tissue infections (Weitzel et al, 2011;Otto et al, 2013), necrotizing fasciitis (Clarke et al, 2010) and a case of eye infection (Funke et al, 1995). Six strains of T. bernardiae have been cultured from blood specimens, but no deaths due to T. bernardiae have been reported.…”

Clinical impact of the use of 16S rRNA sequencing method for the identification of “difficult‐to‐identify” bacteria in immunocompromised hosts

“…Data have been published evaluating the application of the broad‐range 16S rRNA sequencing method in clinical settings (Table ) . Table A lists several publications demonstrating the utility of 16S rRNA polymerase chain reaction (PCR) method to identify organisms cultured from clinical specimens . The molecular method helped accurately identify several isolates to a genus or species level when the conventional methods failed .…”

“…Multiple case reports in the literature have described the use of the broad‐range 16S rRNA PCR method for accurate identification of the organism. “Diphtheroid” was correctly identified as Arcanobacterium bernardiae in a patient with necrotizing fasciitis . Vancomycin‐resistant gram‐positive bacilli recovered from blood were identified as Weissella confusa in 2 patients, one in an allogeneic stem cell recipient and the other in a “burned” patient .…”

Trueperella bernardiae: first report of wound infection post laparoscopic surgery

“…Trueperella bernardiae was previously identified from blood culture, abscesses, and eye infections [3]. There are case reports of severe urinary tract infections complicated by septicemia [6], septic arthritis [7], coinfection with Staphylococcus aureus from chronic osteitis [8], prosthetic joint infection [9], necrotizing fasciitis [10], bacteremia secondary to soft tissue infection [11], bacteremia due to chronic ulcers of the lower limbs [5], diabetic foot infection, and sepsis [12].…”