PO:11:175 | Dermatomyositis and immunosuppressant treatment: a case of Staphylococcus aureus pneumonia in a hospitalized patient

Simona Fichera¹, Andrea Cito¹, Martina Vigilia¹, Maria Morrone¹, Teresa Caferri¹, Crescenzio Scioscia¹, Simone Perniola¹, Giuseppe Lopalco¹, Florenzo Iannone¹. | ¹Unit of Rheumatology, Department of Precision and Regenerative Medicine, Area Jonica, University of Bari, Bari, Italy.

Background. Dermatomyositis (DM) is an autoimmune connective tissue disorder characterized by cutaneous manifestations and muscular involvement. Staphylococcus aureus nosocomial pneumonia is an infection with a high mortality rate, typically characterized by lower respiratory tract symptoms, pulmonary infiltrates on chest X-ray, and at least one positive blood culture in the absence of other sources of bacteremia.

Clinical case. At the time of admission, the 49-year-old male patient exhibited a heliotrope rash on the face and 'V' of the neck, shawl sign, and Gottron's papules (Figure 1.d). He also experienced progressive proximal muscle weakness affecting the shoulder and pelvic girdles, along with new-onset dysphagia (Dysphagia Risk Assessment Scale [DRAS]: 10), confirmed by fibrolaryngoscopy exam. Autoimmunological workup revealed positive antinuclear antibodies (ANA) at a titer of 1/640 and positive anti-fibrillarin autoantibodies. Thigh MRI showed diffuse inflammatory oedema of the pelvic girdle muscles (Figure 1.c). Inflammatory markers were within normal limits, while creatine phosphokinase (CPK) was 579 U/L, aspartate aminotransferase (AST) was 73 U/L, and alanine aminotransferase (ALT) was 66 U/L. On these bases, a diagnosis of DM was established. Treatment was initiated with Methotrexate (MTX) 15 mg/week and Methylprednisolone (MPDN) 1 mg/kg. This regimen led to an improvement in the cutaneous manifestations and partial remission of asthenia, though dysphagia persisted. Consequently, off-label intravenous immunoglobulin (IVIG) at 2 g/kg was requested. Concurrently, approximately two weeks into MTX + MPDN treatment and prior to the first IVIG administration, the patient developed productive cough, general clinical deterioration, episodes of pyrexia (max 38.5°C), and a painful oedematous-pustular lesion on the right hand at a venous access site. Concomitantly, inflammatory markers rose (C-reactive protein [CRP] 77 mg/L, procalcitonin [PCT] 0.19 ng/mL), and blood cultures were positive for Staphylococcus aureus. A chest X-ray revealed an excavated nodule in the right subclavian region (Figure 1.b), which was confirmed by computed tomography (CT) of the chest (Figure 1.a), showing multiple excavated nodules consistent with Staphylococcus aureus infection. Empirical antibiotic therapy was initiated with Ceftriaxone 2g, subsequently adjusted to Piperacillin and Tazobactam 4/0.5g and Linezolid 600mg for 10 days. During treatment, the patient showed progressive clinical and laboratory improvement. Upon completion of antibiotic therapy and confirmation of negative blood cultures and negative echocardiogram exam for endocarditis, the first cycle of IVIG was commenced.

Conclusion. This case highlights the critical importance of accurate infectious risk assessment and its management in immunocompromised patients, such as those with DM, who often undergo invasive supportive procedures and receive high-dose immunosuppressive therapies. It also underscores the necessity of promptly initiating broad-spectrum empirical antibiotic therapy upon the identification of positive blood cultures.