Pyogenic spondylitis caused by Streptococcus dysgalactiae subspecies equisimilis in a patient with nasopharyngeal cancer

Empyema caused by Streptococcus dysgalactiae subsp. equisimilis subsequently to bacteraemia

Streptococcus dysgalactiae subsp. equisimilis (SDSE) commonly causes a variety of infections in older individuals. However, respiratory infections are uncommon. We present the case of an older man with empyema due to SDSE subsequently to bacteraemia. He presented with a 1-day history of fever and laboratory findings revealed an increased white blood cell count and C- reactive protein (CRP) level. Chest CT revealed no infiltration and no pleural effusion. SDSE was detected in the blood cultures. Primary bacteraemia was suspected and antibiotic administration was initiated; however, 2 days later, his right breath sound diminished, and chest radiography revealed right pleural effusion. Thoracentesis yielded cloudy fluid with frank pus; thus, he was diagnosed with empyema due to SDSE, and a drainage tube was placed. Thereafter, his fever improved, and his CRP level decreased. Thus, SDSE can cause empyema probably by haemotological spread of SDSE to the pleura.

Group A Streptococcus dysgalactiae subspecies equisimilis vertebral osteomyelitis accompanied by progressive atlantoaxial subluxation: A case report and literature review

RATIONALE

Clinically, vertebral osteomyelitis commonly occurs in immunocompromised individuals, such as people with diabetes, immunosuppression, chronic liver disease, and malignancy. Microbiologically, vertebral osteomyelitis is commonly caused by Staphylococcus aureus; however, Streptococcus dysgalactiae subspecies equisimilis (SDSE) may also potentially cause vertebral osteomyelitis, albeit rarely. Since no case reports have documented the occurrence of SDSE cervical osteomyelitis accompanied by progressive atlantoaxial subluxation, its clinical characteristics remain uncertain. Herein, we report the first case of progressive atlantoaxial subluxation in addition to cervical osteomyelitis due to septic atlantoaxial arthritis caused by SDSE in an immunocompetent individual, and provide a review of the relevant literature.

PATIENT CONCERNS

A 63-year-old man with hypertension but no history of trauma or musculoskeletal disorders presented with worsening neck pain for 1 month without fever. Physical examination revealed neck pain due to neck retroflexion and tenderness with swelling of the upper cervical spine. No neurological deficit was observed. Magnetic resonance imaging revealed low-intensity areas on a T1-weighted image and high-intensity areas on a short tau inversion recovery image at the C2, C5, and C6 vertebral bodies with atlantoaxial subluxation. Two sets of blood culture tests (aerobic and anaerobic) were performed.

DIAGNOSES

The anaerobic blood culture bottle showed the presence of beta-hemolytic pyrrolidonyl arylamidase-negative SDSE expressing Lancefield group A antiserum. Hence, the patient was diagnosed with SDSE cervical osteomyelitis with atlantoaxial subluxation; intensive intravenous ampicillin (2 g every 6 hours) - which is effective against SDSE - was administered.

INTERVENTIONS

Posterior fusion (occipital bone, C4) was performed on day 33 because a follow-up magnetic resonance imaging on day 31 revealed progression of atlantoaxial subluxation with thickened atlantodental soft tissue.

OUTCOMES

The patient's neck pain was completely relieved after treatment with intravenous ampicillin for 6 weeks, followed by oral amoxicillin (1500 mg) daily for an additional 4 weeks. The patient did not experience recurrence or sequelae during the 2-year follow-up period.

LESSONS

SDSE expressing Lancefield group A antiserum can cause afebrile vertebral osteomyelitis and progressive atlantoaxial subluxation due to the occurrence of septic atlantoaxial arthritis in immunocompetent individuals. Spinal instrumentation for vertebral osteomyelitis may be acceptable after 6 weeks of antimicrobial therapy.