Emendation of the description of the species Corynebacterium propinquum to include strains which produce urease

Abstract

Corynebacterium propinquum is a Gram-positive rod occasionally recovered from clinical infections which, according to 16S rRNA gene sequencing, is most closely related (>99 % sequence similarity) to Corynebacterium pseudodiphtheriticum . The two species are very similar biochemically, commonly differentiated by a single test, the detection of urease, where strains of C. propinquum are described as being urease-non-producing and strains of C. pseudodiphtheriticum are described as urease-producing. In this study, historical and contemporary strains of C. propinquum and C. pseudodiphtheriticum from this laboratory were definitively characterized, which included use of rpoB sequencing. Urease-producing strains of C. propinquum as well as typical urease-non-producing isolates were identified after rpoB sequencing, with six of these being originally identified as C. pseudodiphtheriticum . Based on these observations, we propose emendation of the description of C. propinquum to include strains which produce urease. MALDI-TOF analysis may be a useful tool to differentiate these taxa. Existing commercial databases should be updated to include urease-positive strains of C. propinquum .

Contact Lens-Related Infectious Keratitis with White Plaque Formation Caused by Corynebacterium propinquum

“…The isolate MGJ001 also was resistant to macrolides and lincosamides, strongly suggesting the presence of erm(X). The strain MGJ001 exhibited susceptibility to novel antibiotics, including daptomycin and tigecycline, consistent with susceptibilities observed in a previous report (18). Keratitis is a corneal infection that usually develops after ocular trauma, contact lens wear, or various predisposing corneal diseases.…”

“…However, a recent report reveals the existence of urease-producing strains of C. propinquum; this observation means that C. propinquum isolates may have been misidentified as C. pseudodiphtheriticum and that full differentiation will require sequencing of the rpoB locus (18). Indeed, in the case described in the present work, neither API Coryne nor the 16S rRNA gene sequence was sufficient to accurately identify the isolate to the species level; rpoB gene sequence was needed to demonstrate that the causative strain was C. propinquum.…”

“…In this case, we empirically selected topical GAT and cefmenoxime; intravenous ampicillin subsequently was added in response to a previous report suggesting susceptibility of this species to penicillin (4,18). The majority of C. propinquum strains are constitutively resistant to the macrolides, lincosamides, and streptogramin B as a result of the presence of the erm(X) gene (19).…”

“…propinquum is typically a harmless commensal of human nasopharynx and skin (18,19). This species has been implicated in various opportunistic infections, such as respiratory infection (17,(20)(21)(22)(23)(24), bacteremia (17,25,26), endocarditis (27), osteitis (28), pleural effusion (29), rhino-sinusal infection (30), infection after osteosynthesis (31), trichomycosis axillaris (32), and nongonococcal urethritis (33).…”

Corynebacterium propinquum Keratitis Identified Using MALDI-TOF

“…In one study, C. propinquum was misidentified as C. pseudodiphtheriticum in 10 of 140 MALDI-TOF (Bruker) assays involving 14 strains. 3 Thus, we performed further tests to confirm the identification. A broth assay for urease 4 was negative; some C. propinquum isolates lack this activity, but C. pseudodiphtheriticum strains are positive.…”