Rat bite fever as a presenting illness in a patient with AIDS

Area of Science:

• Microbiology
• Infectious Diseases
• Molecular Diagnostics

Background:

• Septic arthritis in human immunodeficiency virus (HIV)-infected individuals often presents diagnostic challenges due to culture-negative results.
• The etiology of culture-negative septic arthritis in this population remains poorly understood.
• Advancements in molecular techniques offer potential solutions for identifying pathogens in sterile site infections.

Observation:

• A case of septic arthritis was observed in a patient recently diagnosed with HIV.
• The patient presented with symptoms suggestive of septic arthritis, but initial cultures were negative.
• The infection was ultimately attributed to Streptobacillus moniliformis, the causative agent of rat bite fever.

Findings:

• 16S rRNA sequence analysis definitively identified Streptobacillus moniliformis as the pathogen responsible for the septic arthritis.
• This represents the first documented instance of septic arthritis caused by this bacterium in a patient with HIV.
• Molecular confirmation was crucial in establishing the diagnosis due to the failure of traditional culture methods.

Implications:

• This case underscores the utility of molecular diagnostic methods, such as 16S rRNA sequencing, in identifying fastidious or unculturable organisms in culture-negative infections.
• It expands the known spectrum of infectious agents associated with septic arthritis in HIV-positive individuals.
• Further research into the role of rat bite fever in HIV-associated joint infections may be warranted.