The Brief Case: Nontoxigenic Corynebacterium diphtheriae in a Nonhealing Wound

Abstract

A 46-year-old homeless man was transported to the emergency department (ED) after being found minimally responsive outside a public building. Upon evaluation in the ED, the patient was obtunded. He appeared to have sepsis with fever to 39.4°C and tachycardia to 168 bpm, but without hypotension. The patient had a full-thickness wound measuring 6 cm by 5 cm on the dorsal aspect of the distal left forearm with a pink wound bed and overlying purulent, yellowish exudate. The surrounding forearm was erythematous and edematous, with marked edema of the hand distal to the wound and decreased range of motion in the wrist and digits due to stiffness from swelling. There was no area of fluctuance, no bullae, no crepitus, and no exposed bone (Fig. 1). X ray of the extremity showed soft tissue swelling without bony erosion or subcutaneous gas. The patient reported he injects heroin and methamphetamines intravenously, intramuscularly, and intradermally multiple times a day. He has a history of chronic untreated hepatitis C infection and reported the wound on his left dorsal forearm was chronic, having been present for over 10 years with associated chronic osteomyelitis of the underlying radius. The patient had declined deep/surgical culture on multiple occasions. Previous superficial swabs of the wound bed had grown methicillin-resistant Staphylococcus aureus, Streptococcus pyogenes, and diphtheroids. At this encounter, exudative material in the wound bed was once again swabbed and sent for culture prior to starting empirical antibiotic therapy. No organisms or polymorphonuclear cells were observed on Gram stain of the exudate. Blood and urine cultures were negative for growth, and the suspected source of sepsis was superinfection of the chronic left upper extremity wound. The patient was treated empirically with intravenous vancomycin and cefazolin, which he received for 48 h. He had a brisk clinical improvement with normalization of his mental status and marked decrease in edema and erythema of the left upper extremity. He was discharged with prescriptions for doxycycline and cephalexin to complete a planned 14-day course of therapy. Cultures of the exudate collected from the wound grew equal quantities of S. aureus, S. pyogenes, and a diphtheroid (Fig. 2). Previous studies have found an association between S. aureus, S. pyogenes, and the presence of Corynebacterium diphtheriae in wounds; therefore, our standard laboratory practice is to identify diphtheroids, of any quantity, from wound cultures mixed with S. aureus and S. pyogenes (1). The diphtheroid was identified as Corynebacterium diphtheriae by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS; Bruker MALDI Biotyper, BDAL library with 7,311 main spectra [MSP]). Additional testing performed at the Washington State Public Health Laboratories confirmed the identification using traditional biochemical methods, and the Centers for Disease Control and Prevention (CDC) determined this was a nontoxigenic strain.

An infant with nasal vestibulitis and paronychia

“…4,5 If caused by toxigenic strains, ulcers may be covered by a grayish pseudomembrane and may present with more systemic manifestations such as fever and inflammation. 4 Diphtheria infections have been reemerging and causing multiple outbreaks in developed countries. 3,5,7,8 Reports have shown increasing colonization with nontoxigenic strains in different populations including healthy individuals, immunocompromised, and those exposed to poor hygiene, intravenous drug use, and travelers returning from endemic areas.…”

“…diphtheriae using an anti‐toxin vaccine, there have been increasing reports of nontoxigenic strains, mostly causing mild illnesses, 2,3 although severe infections by nontoxigenic strains have been reported 3 . Cutaneous diphtheria tends to be more chronic and may present as nonhealing skin lesions or ulcers 4,5 . If caused by toxigenic strains, ulcers may be covered by a grayish pseudomembrane and may present with more systemic manifestations such as fever and inflammation 4 …”

“…3 Cutaneous diphtheria tends to be more chronic and may present as nonhealing skin lesions or ulcers. 4,5 If caused by toxigenic strains, ulcers may be covered by a grayish pseudomembrane and may present with more systemic manifestations such as fever and inflammation. 4 Diphtheria infections have been reemerging and causing multiple outbreaks in developed countries.…”

“…3,5,7,8 Reports have shown increasing colonization with nontoxigenic strains in different populations including healthy individuals, immunocompromised, and those exposed to poor hygiene, intravenous drug use, and travelers returning from endemic areas. 4,5,7,8 According to recent UK surveillance data from 2009 to 2017, most toxigenic C. diphtheriae were isolated from children with cutaneous manifestations. 8 Transmission is through close contact with infectious material from skin lesions or respiratory secretions.…”

“…Diphtheria infections have been reemerging and causing multiple outbreaks in developed countries 3,5,7,8 . Reports have shown increasing colonization with nontoxigenic strains in different populations including healthy individuals, immunocompromised, and those exposed to poor hygiene, intravenous drug use, and travelers returning from endemic areas 4,5,7,8 . According to recent UK surveillance data from 2009 to 2017, most toxigenic C .…”