Hand tendon abscess due to Staphylococcus condimenti

Dear Editor,

Coagulase-negative staphylococci are commensals of human skin and mucous membranes.¹ More than 45 species of these microorganisms have been identified to date.²Staphylococcus condimenti (S. condimenti) is a coagulase-negative staphylococcus, described in 1998,³ generally considered to be non-pathogenic.⁴ This microorganism is not part of the human skin microbiota, but has been found in fermented foods and soy sauce.¹ Its genome contains several virulence factors, including leukocidin-like proteins.⁵ The first documented case of infection with this organism was a catheter-related bacteraemia in a patient with severe dilated cardiomyopathy.⁶ Other reported cases have included severe skin and soft tissue infection,⁵ meningitis,⁴ surgical site infection⁷ and spondylodiscitis.¹

We present a case of tenosynovitis due to S. condimenti in a 43-year-old woman, a teacher by profession, who had no contact with pets or involvement with rural activities or gardening, who came to Accident and Emergency with a four-day history of pain and loss of function, inflammation, heat and flushing of the third finger of her left hand. The onset of symptoms had been sudden, with no prior trauma, insect bite or foreign body, although they seemed to stem from a nodular lesion that the patient had developed five months previously. She had no fever or other accompanying symptoms. The patient had no immunosuppression or other risk factors, but her previous history included the fact that she had morbid obesity.

She had initially consulted her health centre, where she was prescribed antimicrobial treatment with amoxicillin/clavulanic acid (875/125 mg 3 times a day) with adequate adherence. In the absence of improvement, she went to Accident and Emergency where, after ruling out bone involvement with a plain X-ray, she was discharged with the same treatment. However, she returned to Accident and Emergency 48 h later as the condition had become worse. At this point, she had leucocytosis with a left shift (21.80 × 10³/µl), elevated C-reactive protein (3.60 mg/dl) and procalcitonin at normal levels (0.02 ng/ml).

Physical examination revealed slight swelling with oedema in the middle and proximal phalanges of her third finger which prevented flexion and full extension, with local pain on palpation, slight increase in temperature, but no oozing or wound. After assessment, the diagnosis was established as tenosynovitis of the third finger of her left hand, and admission for surgery was recommended.

During the surgical procedure, which consisted of draining the abscess and the tendon sheath, three samples were taken from the lesion and sent to the microbiology laboratory in a sterile container. Gram staining was performed and samples were seeded on blood agar, chocolate agar, MacConkey agar and Sabouraud agar, which were incubated in CO₂ atmosphere and on Brucella agar and BBE-amikacin agar plates in anaerobiosis. Gram-positive cocci with staphylococcal morphology were observed in the Gram stain.

After 48 h incubation, whitish colonies grew on blood agar and chocolate agar which were catalase positive, oxidase negative and non-haemolytic. By MALDI-TOF mass spectrometry (Becton Dickinson^TM Bruker MALDI Biotyper® CA System) they were identified as S. condimenti with a score of 2.50. This microorganism was isolated in pure culture from the three samples sent to the laboratory. The microorganism was sent to Spain's National Microbiology Centre where identification was confirmed by PCR and sequencing of the 16S rRNA and tuf genes. The antibiotic sensitivity study was performed using broth microdilution panels (MicroScan WalAway96 plus System Beckman Coulter®), being sensitive to penicillin, oxacillin, cefoxitin, gentamicin, levofloxacin, moxifloxacin, vancomycin, teicoplanin, erythromycin, clindamycin, linezolid and trimethoprim/sulfamethoxazole, using the cut-off points established by the European Committee on Antimicrobial Susceptibility Testing (EUCAST; www.eucast.org). A commercial PCR (GeneXpert powered by Cepheid innovation: Xpert® MRSA/SA SSTI [REF: GXMRSA/SA-SSTI-10]) was performed and detection of the mecA gene was negative.

We emphasise the aggressive and invasive nature of this infection since, despite drainage and adequate antibiotic therapy with amoxicillin/clavulanic acid, a second surgical intervention was necessary due to the poor outcome, probably due to the residual presence of the microorganism at the focus. In the end, the postoperative period was uneventful and the patient was discharged from hospital after two weeks.

This case demonstrates, as has been done in other studies,⁵ the pathogenicity of multiple antimicrobial-sensitive S. condimenti as a causative agent of skin and soft tissue infections in patients without immunosuppression.

We believe that the prolonged course of the infection, which required several surgical interventions, may have been due to the aggressiveness of the microorganism and the failure to completely eliminate the focus. S. condimenti infection is rare, but it can cause serious infections in healthy people. The isolation of new species of coagulase-negative staphylococci from surgical specimens, which are not part of the skin microbiota and in pure culture, means we have to consider these new pathogens in the aetiology of skin and soft tissue infections. However, at the same time, availability of new diagnostic methods such as mass spectrometry (MALDI-TOF) means we are able to effectively identify these microorganisms at an early stage.

Funding

The authors declare that they received no funding to conduct this study.

Conflicts of interest

The authors declare that they have no conflicts of interest.

Acknowledgement

To Dr María-José Medina Pascual, Centro Nacional de Microbiología [Spanish National Microbiology Centre] (ISCIII, Majadahonda, Madrid), for the sequencing of the isolate.