A typical Presentation of Haemophilus influenzae Septic Arthritis: A Case Report

Abstract

Septic arthritis (SA) caused by Haemophilus influenzae (H. influenzae)is amonga few known orthopedic emergencies that can result in significant joint and cartilage destruction. H.influenza is a small, non-motile, Gram-negative, pleomorphic opportunistic bacterium, a strict human pathogen that commonly inhabits the upper respiratory tract and istransmitted via airborne droplets or direct contact with respiratory secretions. It can exist both as encapsulated and non-encapsulated (non-typeable) strains, latter being associated with most of the non-invasive infections. Based on the unique polysaccharide capsule of encapsulated strains, they are divided into 6distinct serotypes, “a” through “f.” H. influenzae type b (Hib) is most known for causing severe invasive diseases, including acute epiglottitis, meningitis, pneumonia, septic arthritis, and bacteremia, particularly in non-immunized pediatric populations [1]. Infections due to other encapsulated serotypes (e.g., types a, c, d, e, and f) and non-typeable strains have been increasingly reported, particularly in immunocompromised individuals and older adults. Septic arthritis can be caused secondary to bacterial, viral or fungal infections, Staphylococcus aureusimplicated as the most common cause among bacterial etiological agent [2].  Less commonly, it can be caused by bacteria such as Kingellakingae, Group A Streptococcus, H. influenzae non-type b (NTHi), Neisseria gonorrhoeae, and Mycobacterium tuberculosis [3]. While most cases of septic arthritis occur in previously healthy individuals, immunodeficiency significantly increases the risk of infection, especially with less common organisms. Patients with conditions such as Combined Variable Immunodeficiency (CVID) or other agammaglobulinemia are particularly vulnerable due to their impaired ability to produce antibodies [4]. Risk factors for H.influenzae infection includeextremes of age, underlying immunocompromising conditions (ie, complement deficiency, hypogammaglobulinemia, sickle cell anemia, functional asplenia, HIV, malignancy), chronic pulmonary disease, smoking, HIV, alcoholism during pregnancy [5].