Subscapular abscess is a rare surgical diagnosis, where a collection of pus forms between the subscapularis muscle and the chest wall. It has been described in only a few case reports. Predisposing conditions for this type of abscess include an immunocompromised state, recent infection, diabetes, end-stage renal disease, IV drug use, and trauma to the shoulder area causing hematoma formation [1–4]. In a subscapular abscess, S. aureus is most commonly identified. The organism was S. aureus in four cases [1–4], methicillin-resistant S. aureus in three cases [5–7], Panton-Valentine leucocidin positive S. aureus in one case [8], H. influenza in one case [9], and no organism was grown in the last case [11].
To the best of our knowledge, this is the first report of a subscapular abscess caused by E. coli, which is a common gram-negative bacterium and the most common cause of bloodstream infection. However, the epidemiology has not been well defined in the non-selected population. A cohort study showed that infants and elderly were at highest risk for E. coli infection [12]. Hematogenous transmissions of E. coli usually occur as a complication of focal infections of the urinary or gastrointestinal tracts, but occasionally also can occur as IV drug use [13].
Our patient did not have any known immunocompromising condition, diabetes, or renal disease. However, he had been treated with IV antibiotics for six weeks for recent pneumonia in the upper left lobe of the lung. The cultures from the abscess fluid as well as blood cultures obtained at the time of admission revealed extended-spectrum beta-lactamases (-) E. coli. However, urinalysis and urine culture results were negative. We believe that the patient might have been vulnerable to transient bacteremia, allowed translocation of E.coli from the IV injection route, ultimately resulting in an E.coli subscapular abscess.
Meanwhile, manual therapy and exercise, usually delivered together as components of a physical therapy intervention, are commonly used interventions for frozen shoulder. It includes any clinician-applied movement of the joints and other structures, for example, mobilization or manipulation. Mobilization is employed to reduce pain by stimulating peripheral mechanoreceptors and inhibiting nociceptors, and to increase joint mobility by enhancing exchange between synovial fluid and cartilage matrix [14, 15]. Manual therapy and stretching exercises have been demonstrated to reduce pain and improve function in a frozen shoulder [10]. Düzgün et al.[16] reported that manual therapy may be safely applied in frozen shoulder. He also suggested that manual therapy has a positive effect on pain, range of motion, muscular strength and level of the functional activity on frozen shoulders following intervention by physiotherapists. However, manual or massage therapy can cause complications, such as muscle bleeding, muscle rupture, or myositis ossificans [17, 18]. Sasanuma et al.[19] reported that MRI in patients with severe frozen shoulder after manipulation showed capsule tears, labrum tears, and bone bruises in the humeral head.
In present case, the patient complained of experiencing severe pain with popping sound during a manual therapy of the left shoulder for frozen shoulder. MRI was observed with abscess in subscapularis. The minor trauma caused by manual therapy in severe frozen shoulder may have led to a small hematoma in the subscapular space that subsequently was seeded by extended-spectrum beta-lactamases (-) E. coli.
In summary, hematogenous transmissions of E. coli may occur as a complication of long-term intravenous drug use. Surgeons and physiotherapists should pay attention to the subscapular abscess as a rare complication of manual therapy in severe frozen shoulder.