A Case Report & Literature Review Glenohumeral Joint Sepsis Caused by Streptococcus mitis: A Case Report Oren I. Feder, BS, and Konrad I. Gruson, MD In this article, we report a case of glenohumer- Abstract al joint septic arthritis caused by S mitis. To our Septic arthritis of the shoulder girdle knowledge, such a case has not been previously remains relatively uncommon, with reported in the English literature. Given the low Staphylococcus aureus and β-hemolytic virulence of this orally based bacterium, treating streptococci the typical offending organ- physicians must maintain clinical suspicion for the isms in adult patients. Rare cases of Strep- organism in the setting of persistent joint effusion tococcus viridans, an oral bacterium with and pain in association with periodontal disease low virulence, have been reported in the or trauma. The patient provided written informed setting of septic arthritis, mostly involving consent for print and electronic publication of this the knee joint or the sternoclavicular joint. case report. In this article, we report a case of Streptococcus mitis infection of the Case Report glenohumeral joint that likely resulted A right-hand-dominant 54-year-old man presented from hematogenous spread after oral to Dr. Gruson with complaints of persistent right trauma in a patient with poor underlying shoulder pain associated with worsening range dentition. Prompt diagnosis followed by of motion (ROM). Three weeks earlier, the patient arthroscopic irrigation and débridement reported being assaulted and noted progressive of the glenohumeral joint resulted in a swelling about the right shoulder. He denied fevers, chills, or prior shoulder problems. Although satisfactory clinical outcome. his past medical history was remarkable for hepa- titis C and diabetes, he was not taking any diabetic medications at that time. A review of systems eptic arthritis predominantly involves the was remarkable for poor dental hygiene, and the weight-bearing joints of the hip and knee, patient was missing several teeth, which he said S which account for nearly 60% of cases.1 In had been knocked out during the assault. Physical contrast, the shoulder joint is involved in 10% to examination revealed diffuse tenderness about 15% of cases, though this number may be higher the right shoulder and severe pain with all passive among intravenous (IV) drug users.2 The most movement. The shoulder was pseudoparalyzed. common causative organisms are the Staphylo- There were no subcutaneous collections, wounds, coccus species, followed closely by β-hemolytic or ecchymosis about the shoulder. Mild calor was streptococci, with these 2 groups accounting for noted on the right shoulder relative to the left. Ra- more than 90% of all cases.3 The Streptococcus diographs of the right shoulder showed no acute viridans group belongs to normal oral flora residing osseous abnormalities. predominantly on the surface of teeth. Although Magnetic resonance imaging (MRI), which well known for its ability to colonize heart valves was urgently obtained to assess the integrity of and frequently cause bacterial endocarditis, this the rotator cuff and the location of the effusion, group has rarely been associated with septic showed a large subacromial and glenohumeral arthritis. Furthermore, Streptococcus mitis, a joint effusion as well as diffuse muscular edema subgroup of S viridans, has been implicated even (Figures 1A-1C). At follow-up, the patient reported less commonly. having lost 10 pounds since his assault, as well Authors’ Disclosure Statement: The authors report no actual or potential conflict of interest in relation to this article. www.amjorthopedics.com September/October 2016 The American Journal of Orthopedics ® E343 Glenohumeral Joint Sepsis Caused by Streptococcus mitis: A Case Report as new-onset fevers and chills. C-reactive protein resulted in egress of turbid fluid, which was sent (CRP) level was 5.2 mg/dL (reference, <0.9 mg/ for culture. The subacromial space and the gle- dL), and erythrocyte sedimentation rate (ESR) was nohumeral joint were thoroughly lavaged and the 48 mm/h (reference, <21 mm/h). White blood cell copious hemorrhagic synovitis débrided (Figures count was normal. Fluoroscopy-guided aspiration 2A, 2B). Chondral surfaces appeared grossly intact. of the glenohumeral joint, performed under sterile All cultures from the surgery ultimately yielded S conditions, yielded only 4 cc of hematoma. Gram mitis. A peripherally inserted central catheter line stain was negative; though there was no growth was started, as was a 4-week course of IV ceftri- on the primary plates, broth cultures grew S mitis. axone, as recommended by an infectious disease Repeat bloodwork demonstrated persistently in- consultant. At postoperative visits in the orthopedic creased CRP level (6.4 mg/dL) and ESR (55 mm/h). clinic, a new-onset right axillary abscess consist- In light of the elevated infection findings of the ing of purulent material and organized hematoma laboratory tests and the positive culture, urgent was drained. After the ceftriaxone regimen was arthroscopic irrigation and débridement of the completed, a 4-week course of oral amoxicillin was right shoulder were indicated. Given the organism started. identified, transesophageal echocardiography was The 8-week course of antibiotics normalized the performed; there were no valvular vegetations. patient’s ESR to 13 mm/h. Follow-up MRI showed Creation of the posterior glenohumeral portal improvement in the soft-tissue edema. Clinically, A B C Figure 1. Proton density-weighted coronal oblique (A, B) and axial (C) magnetic resonance imaging shows large glenohumeral joint and subacromial space effusion with adjacent muscular edema. Rotator cuff appears thin but intact. A B Figure 2. (A) Arthroscopic view from posterior portal demonstrating intact nature of articular cartilage with hemorrhagic synovitis overlying anterior capsule. (B) Arthroscopic view of subacromial space from lateral portal. Diffuse hemorrhagic bursitis overlying posterior-superior rotator cuff was exten- sively débrided. E344 The American Journal of Orthopedics ® September/October 2016 www.amjorthopedics.com O. I. Feder and K. I. Gruson the patient reported minimal shoulder pain. He nous spread. was undergoing physical therapy to regain strength There should be no delay in diagnosing septic and ROM. arthritis, and infected material should be removed from the joint. In animal models, complete joint Discussion destruction occurred only 5 weeks after inocula- Staphylococcus aureus is the leading causative tion with Staphylococcus aureus.10 Garofalo and organism of septic arthritis, accounting for more colleagues18 reported a trend toward improved than 60% of all cases.4 Conversely, the Strepto- functional outcomes after earlier operative coccus viridans group is rarely implicated in septic treatment. The choice of open surgical drainage arthritis, accounting for <1% of cases.4 S viridans vs repeat needle aspiration seems to be of little is part of the commensal oral flora and has low consequence, as both have good long-term out- virulence. This heterogeneous group is subdivided comes, but open surgical drainage seems to result into S mitis, S salivarius, S anginosus, S mutans, in better long-term functional ROM.2,9 However, and S bovis. The S mitis group is further subdivided results of a recent study suggested surgical treat- into S sanguinis (formerly known as S sanguis) and ment is not always superior to medical treatment S mitis. Infection by an organism of the S viridans for septic arthritis in native joints.19 In some cases group usually occurs on a previously injured focus, involving S viridans species, treatment consisted and the organism is a causative agent of bacterial of a combination of IV antibiotics and onetime or endocarditis.5 Reported cases of septic arthritis repeat aspiration;6,12-15 treatment in the remaining caused by S viridans have predominantly involved cases was surgical débridement.5,7,16,17 Given that the knee joint—with severe osteoarthritis, poor S viridans is associated with bacterial endocarditis, dental hygiene, and prior IV drug use identified as echocardiography is essential if this organism is to risk factors.5-7 The shoulder joint is seldom involved be identified. Medical management and antibiotic in septic arthritis; estimated incidence is under treatment should be initiated after consultation 8%.8 Although overall incidence may rise in an with medical and infectious disease specialists.19 increasingly elderly patient population, incidence of We have reported a case of septic shoulder shoulder infection remains low.2,9 caused by S mitis, a low-virulence organism The main routes for developing septic arthritis seldom associated with joint infection. The include direct inoculation secondary to penetrating patient’s infection likely resulted from hematog- trauma or hematologic spread.10 Coatsworth and enous spread from the oral cavity (dentition was colleagues11 reported on iatrogenic S mitis septic poor). Urgent aspiration of the joint and baseline arthritis of a shoulder arthroplasty during ultraso- infection laboratory tests are recommended. MRI nography-guided aspiration by a technician who of the shoulder may show an effusion. Urgent was not wearing a mask. Our institutional policy arthroscopic irrigation and débridement can yield is to perform joint aspiration under strictly sterile good clinical outcomes. conditions, which were adhered to in the present case. We surmise our patient