Streptococcus pyogenes flexor tenosynovitis

Group A Streptococcus (GAS) is a well-known pathogen that causes diseases ranging from cellulitis and scarlet fever to necrotizing fasciitis. It is highly prevalent in developing countries and populations with a low socioeconomic status. Children, the immunocompromised and the elderly are at greatest risk of GAS infections and their sequelae (Avire et al., 2021). There have been recent reports of ‘outbreaks’ of GAS in the USA, Canada and Europe (Garancini et al., 2023).

Although this pathogen has been described as causing hand infections, including invasion of the tendons and tendon sheaths, it is very rare for GAS to present as isolated finger flexor tenosynovitis (FTS) (Hankins and Southern, 2008). We report a rare case of a rapidly progressing FTS caused by GAS in an otherwise healthy individual.

A 50-year-old woman with no past medical history presented with rapidly progressing right index finger pain, swelling and erythema over a 12-hour period. She reported no history of penetrating trauma or other inciting event. On examination, there was no skin involvement, but all four Kanavel signs were present with pain radiating to the central palm. She was systemically sick, with a white blood cell count of 18,000/mm², C-reactive protein of 44 and a tachycardia of 100 beats/minute, raising concern about sepsis. An ultrasound examination revealed a large fluid collection in the flexor tendon sheath, indicating FTS. Urgent surgery revealed murky fluid within the tendon sheath and an inflamed tenosynovium, a biopsy of which was sent for pathology and culture. Distally there was frank pus and more murky fluid. The flexor tendon sheath was thoroughly irrigated. Aerobic cultures were positive for streptococcus pyogenes (GAS). Pathology reported inflammatory synovitis. A 3-week course of amoxicillin 1 g three times a day was started, according to the sensitivity.

Skin involvement developed rapidly despite no initial skin signs and treatment with antibiotics and surgical drainage (Figure 1). Some bullae progressed to necrosis and eschar formation.

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Figure 1.

The finger 1 day after surgery. After surgery, the finger quickly developed skin involvement with erythema and bullae, first along the volar surface of the finger and then dorsally.

By 10 days postoperatively, areas of eschar had developed on the palmar aspect of the finger. The finger gradually improved although despite antibiotic treatment there was further necrosis and at times some areas had recurrent erythema, swelling and discomfort. Local bacitracin ointment was added to address the skin condition. At 11 weeks postoperatively, the necrotic area changed to healthy granulation tissue. Despite some functional improvement, osteomyelitis occurred in the tuft of the terminal phalanx with bony lysis.

The initial presentation of isolated FTS in this patient differs from other descriptions of FTS in that systemic symptoms and signs were prominent but the patient developed skin involvement typical of GAS. As with other GAS infections, rapidly advancing local and general involvement is a hallmark of the infection (Avire et al., 2021). FTS caused by GAS requires swift identification to avoid serious and potentially life-threatening effects. A high index of suspicion must be maintained to prevent these complications. Furthermore, recent reports of GAS outbreaks in developed countries underscore the need for vigilance. Severe infections, such as necrotizing fasciitis and toxic shock syndrome, are being documented with increasing frequency, particularly in children.(Garancini et al., 2023). These outbreaks may be related to specific bacterial mutations (Bah et al., 2023; Davies et al., 2023).

In summary, this was a rare initial presentation for an otherwise ubiquitous bacterium. There is documentation of epidemiological changes of GAS, which surgeons should be aware of, along with the treatment options that are available.