Identification and Clinical Significance of Helcococcus species, with Description of Helcococcus seattlensis sp. nov. from a Patient with Urosepsis

Abstract

Helcococcus spp. are Gram-positive, catalase-negative, facultatively anaerobic cocci that are associated with wound and prosthetic joint infections as well bacteremia and empyema. Five Helcococcus spp. strains were isolated from our patient population, including 2 strains of Helcococcus kunzii from trauma-associated wounds, 2 Helcococcus sueciensis strains from blood and abscess, and a novel Helcococcus spp. strain from blood associated with urosepsis. Based on the phenotypic and phylogenetic evidence, we propose that the unknown bacterium be classified as Helcococcus seattlensis sp. nov. We found that all 5 tested Helcococcus strains grew as satellite colonies around Staphylococcus aureus and, interestingly, both H. kunzii strains were isolated together with S. aureus. In addition to 16S rRNA gene sequencing, conventional methods for leucine aminopeptidase (LAP) and pyrrolidonyl arylamidase (PYR) testing can be cost-effective and efficient for differentiation of Helcococcus spp. from Abiotrophia and Granulicatella species. Using nonstandard methods, we found that all tested Helcococcus spp. had high MICs of >4/76 g/ml for trimethoprim-sulfamethoxazole, an antibiotic commonly used to treat urinary tract infections. High MICs for erythromycin, azithromycin, and clindamycin, and intermediate to high MICs for moxifloxacin, levofloxacin, and gentamicin were also observed among the Helcococcus strains.

Identification and Clinical Significance of Helcococcus kunzii in Human Samples

“…This predominance of H. kunzii was also demonstrated in venous leg ulcers where it was the fourth most frequently seen bacterial species (22%) in patient wounds, after Staphylococcus aureus (64%), Corynebacterium striatum (61%), and Pseudomonas aeruginosa (33%) (27). As reported here, patients are usually older than 57 years of age (5,13,16,17,19,21,23,24). H. kunzii was mostly isolated with concomitant bacteria (95% of cases), particularly staphylococci, Enterobacteriaceae, and anaerobes, as previously described (5,13,(15)(16)(17).…”

“…As part of the human skin flora, H. kunzii is primarily recovered from infected wounds of the lower limbs, particularly foot ulcers with cellulitis in diabetic patients (1,5,(13)(14)(15)(16)(17). It has also been found in cultures of skin/soft tissue abscesses (1,6,16,18,19).…”

“…H. ovis has been described from different animals but never from humans (3,(6)(7)(8)(9)(10)(11). H. sueciensis has been isolated only in humans from two wound infections and one bacteremia infection (4,5). H. seattlensis has been isolated once in blood from a patient suffering from urosepsis (5).…”

“…To date, four species have been described: Helcococcus kunzii (1993) (1), Helcococcus ovis (1999) (3), Helcococcus sueciensis (2004) (4), and Helcococcus seattlensis (2014) (5). H. ovis has been described from different animals but never from humans (3,(6)(7)(8)(9)(10)(11).…”

“…H. sueciensis has been isolated only in humans from two wound infections and one bacteremia infection (4,5). H. seattlensis has been isolated once in blood from a patient suffering from urosepsis (5). A fifth species, Helcococcus pyogenes, involved in a unique human case of prosthetic joint infection was proposed, but its name has not been validated yet (12).…”