SHM Converge Scientific Abstract ePoster Gallery-An Unusual Invasive Poly-Articular Septic Arthritis Case by Haemophilus Influenzae

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This case describes an unusual invasive infection in a healthy, fully immunized 17-year-old male who developed bacteremia and polyarticular septic arthritis caused by beta-lactamase–negative <em>Haemophilus influenzae</em>. He presented with two days of worsening left hip and right wrist pain, along with chills and night sweats, but no fever. Exam showed marked tenderness and limited range of motion in the right wrist/thumb and left sacroiliac/hip region.

Laboratory studies revealed elevated inflammatory markers, leukocytosis, and microcytic anemia. Blood cultures grew <em>H. influenzae</em> within 20 hours. MRI showed left sacroiliac joint synovitis/capsulitis with associated pelvic phlegmon and surrounding myositis, plus a large inflammatory wrist effusion with synovial thickening and enhancement. Joint aspirations were non-diagnostic, and the staphylococcal growth from one sample was felt to be a contaminant.

Treatment started with vancomycin, then switched to IV ceftriaxone after the blood culture result. He underwent prolonged therapy with 3 weeks of IV ceftriaxone followed by 4 weeks of oral cefdinir and ultimately achieved complete remission. CRP was monitored serially and normalized by the end of treatment.

The discussion emphasizes that vaccine-preventable organisms like <em>H. influenzae</em> are still important causes of invasive disease, even in immunized individuals. Non-type b and non-typeable strains appear to be increasingly responsible for invasive infections, but bacteremic polyarticular septic arthritis remains rare in adolescents. The case also highlights that standard empiric septic arthritis regimens may not cover <em>H. influenzae</em>, so culture results should prompt serotyping and consideration of underlying immunodeficiency. Early MRI, repeat imaging if not improving in 24–48 hours, and serial CRP monitoring are recommended to guide management.

Asset Subtitle

Divya Singh

Meta Tag

Author List Aline Tanios, Divya Singh, Luke Stephens

Category Clinical Vignettes

Concept Haemophilus influenzae

Concept Septic Arthritis

Concept Polyarticular septic arthritis

Concept Bacteremia

Concept Empiric Antimicrobial Regimen

Distinguished Non-Finalist

Presenter Organization St Louis University

Presenting Author Divya Singh

Track Pediatric

Keywords

Haemophilus influenzae

bacteremia

polyarticular septic arthritis

adolescent infection

beta-lactamase negative

ceftriaxone

cefdinir

MRI

C-reactive protein

invasive disease

Haemophilus influenzae

Septic Arthritis

Polyarticular septic arthritis

Bacteremia

Empiric Antimicrobial Regimen