Prevotella bivia Septic Arthritis in an Immunocompetent Adult: A Case Report and Review of Literature

Abstract

Septic arthritis is a medical emergency that requires prompt diagnosis to prevent long-term intra-articular complications. Prevotella bivia is an anaerobic gram-negative rod which has been infrequently reported to cause septic arthritis. We present a 49-year-old female that presented with spontaneous left knee pain and swelling without history of insult to the knee. She was initially misdiagnosed with patellar tendinitis and gout but later underwent joint aspiration due to worsening symptoms, which demonstrated 60 800/µL nucleated cells with a polymorphonuclear burden consistent with septic arthritis. Arthroscopy with irrigation and drainage was subsequently performed, and the patient was started on empiric antibiotics while awaiting cultures. Cultures grew Prevotella bivia, and antibiotics were deescalated to ertapenem alone followed by oral metronidazole. Prevotella species as a source of septic arthritis is rare, and its occurrence in a patient without known insult to the knee is even more uncommon. It is essential that it is recognized to treat appropriately and prevent long-term loss of function in the joint.

Introduction

Prevotella bivia is an anaerobic gram-negative rod that was previously classified as Bacteroides bivia. It is a microorganism commonly isolated from the female genital tract and can cause urinary tract infections and pelvic inflammatory disease. ¹ It is also associated with preterm premature rupture of membranes (PPROM) and is infrequently seen in oral infections. ²

Septic arthritis is recognized as a medical emergency that requires prompt hospitalization and rapid diagnosis to prevent long-term intra-articular complications. The incidence of septic arthritis arising in native joint spaces is estimated between 4 and 12 per 100 000 patient-years. ³ Mortality is still 2% to 14% despite the prevalence of antibiotic use, and close to one-third of survivors suffer from long-term functional impairment secondary to joint destruction and deterioration. ³ Septic arthritis due to Prevotella infection is rare.

Case Presentation

A 49-year-old female with a past medical history of right hip arthroplasty 8 years prior presented with a one-and-a-half-week history of left knee pain and swelling with no preceding trauma, tick bites, sexually transmitted infections, or personal history of autoimmune or inflammatory conditions.

Five days prior, she was seen by her primary-care provider who suspected patellar tendonitis and recommended conservative management. Owing to worsening pain, she presented to urgent care the following day where C-reactive protein (CRP) was found to be elevated at 256 mg/dL, while a complete blood count, basic metabolic panel, and uric acid level were normal. She was given the presumptive diagnosis of gout and was prescribed prednisone and hydrocodone.

Her condition continued to deteriorate which prompted a subsequent visit to the orthopaedic walk-in clinic a few days later. At this time, she exhibited leukocytosis with a white blood cell count of 11.8 K/µL, and CRP was still elevated at 239 mg/dL. She was subsequently admitted and underwent aspiration of the knee joint which demonstrated 60 800/µL nucleated cells with 89% polymorphonuclear cell burden and no crystals.

The patient underwent arthroscopy with irrigation and debridement. Antibiotic treatment was initiated with intravenous (IV) vancomycin and was subsequently transitioned by infectious disease to 500 mg daptomycin and ertapenem. Culture of the aspirate later grew Prevotella bivia.

The antibiotic regimen was deescalated to ertapenem alone. Following completion of intravenous antibiotics, the patient was treated with oral metronidazole.

Three weeks following discharge from the hospital, the patient’s condition had improved significantly with only mild pain and joint stiffness. At that point, her CRP at this point had been trending downward, and her leukocytosis had resolved. Five weeks following discharge, the patient no longer had knee pain or swelling, and her CRP had normalized. She was encouraged to follow-up with physical therapy to improve mild stiffness and work on regaining minimal losses in range of motion and strength.

Discussion

Diagnosis of septic arthritis is often challenging as its clinical presentation has considerable overlap with other noninfectious inflammatory articular conditions such as gout, pseudogout, rheumatoid arthritis, and osteoarthritis. These diseases themselves increase the risk of developing septic arthritis, so clinicians ought to have a high index of suspicion in someone with a medical history of the aforementioned conditions that is presenting with acute onset mono-articular pain, swelling, and deficits in range of motion. Common microbiological isolates in adults with septic arthritis of native joints include Staphylococcus aureus, Streptococcus species., Enterococcus species., Escherichia coli, Salmonella species., Pseudomonas aeruginosa, and Candida species. ⁴ To our knowledge, there are only 3 other case reports in the literature of patients with Prevotella bivia septic arthritis and 5 patients with septic arthritis secondary to other Prevotella species (Table 1). Two of the cases of Prevotella bivia infection are confounded by some other associated risk factor such as recent intra-articular hip injection and rheumatoid arthritis.^5,6 Our patient presented with involvement of a native knee joint, no medical history of arthropathies, no inciting trauma, and immunocompetency, similar to one previously reported case of a 76-year-old male. ⁷ Anaerobic organisms such as Prevotella bivia are uncommon isolates in septic arthritis, and the presented patient’s unremarkable history made this an unusual case.

Table 1.

Previously Reported Cases of Septic Arthritis Secondary to Prevotella Species.

Case	Age/sex	Joint infected	Cultured organism	Preceding insult	Treatment	Outcome
Our patient	49, F	Left knee	Prevotella bivia	None	Arthroscopy with irrigation and debridement; ertapenem for 4 weeks followed by oral metronidazole	Resolution at completion of antibiotics
Salman and Baharoon 7	76, M	Left knee	Prevotella bivia	None	Joint drainage and debridement; metronidazole for 4 weeks	Resolution at completion of antibiotics
Laiho and Kotilainen 5	23, F	Left hip	Prevotella bivia	Destructive seronegative polyarthritis; intra-articular injection 3 weeks prior	Surgical drainage; imipenem for 19 days then oral amoxicillin-clavulanic acid for 2 weeks	Inflammatory synovitis with aseptic necrosis of caput femoris (secondary to underlying polyarthritis)
Alegre-Sancho et al 6	77, M	Left knee	Prevotella bivia	Rheumatoid arthritis treated with low-dose corticosteroids	Surgical drainage and debridement; metronidazole for 4 weeks	Patient expired from gastrointestinal bleed (unrelated to infection)
Ely 8	50, F	Right sterno-clavicular joint	Prevotella melaninogenicus	Proximal clavicle osteomyelitis with unknown source of infection	Surgical debridement and irrigation; ciprofloxacin and metronidazole then ampicillin-sulbactam for 6 weeks	Resolution at completion of antibiotics
Fe Marques et al 9	75, M	Left knee	Prevotella loescheii	Dental root extraction 2 weeks prior	Joint washout; amoxicillin-clavulanic acid for 4 weeks	Resolution at completion of antibiotics
Tibrewal and Kenwrigh 10	56, M	Left hip	Bacteroides melaninogenicus (Prevotella melaninogenicus)	4-year history of symptomatic osteoarthritis	Joint washout and removal of necrotic femoral head; metronidazole and piperacillin and gentamycin	Resolution at completion of antibiotics
Dodd et al 11	63, F	Left knee	Bacteroides melaninogenicus (Prevotella melaninogenicus)	Rheumatoid arthritis: dental root infection later identified	Metronidazole for 3 months	Resolution at completion of antibiotics
Harch et al 12	52, M	Left knee	Prevotella intermedia	None	Piperacillin/tazobactam and oral metronidazole for 5 weeks followed by oral clindamycin	Resolution at completion of antibiotics

Septic arthritis typically develops secondary to hematogenous spread of a pathogenic organism to the involved joint. When anaerobic bacteria are implicated, Bacteroides fragilis is the most commonly isolated microorganism. ¹³ Other means of dissemination, however, are commonly seen including contiguous spread from a neighboring infection or direct inoculation following procedures such as intra-articular injections and arthroscopies. Prevotella bivia typically has an insidious pathological evolution. Most isolates are β-lactamase positive with elastolytic activity that drives destruction of host tissue. ² Moreover, Prevotella bivia generally requires the presence of an aerobic organism as this increases its pathogenicity. ³ This aerobic organism serves as the predominant pathogenic species in the early stages of infection. ² As the infection progresses, however, Prevotella bivia replaces the aerobic organism as the predominant pathogenic organism. ² In our patient, the only microbiological isolate was Prevotella bivia, which is supported by the timeline as our patient presented several days after the onset of her symptoms.

It is common practice for clinicians to recommend arthrocentesis with gram stain and culture for diagnosis, empiric antibiotic implementation, and joint drainage via serial closed-needle aspiration, arthroscopy with irrigation and debridement, or arthrotomy. ³ Patients such as the one presented above pose challenges to clinicians as benign medical histories coupled with significant overlap in clinical and laboratory presentations between septic arthritis and other noninfectious inflammatory articular conditions can create difficulty in rapid diagnosis and treatment. Of note, it is important to appreciate that gram-negative septic arthritis is reported to have worse outcomes than septic arthritis caused by gram-positive organisms. ¹⁴ Within the realm of gram-negative bacillary septic arthritis, lower cure rates, worse therapeutic outcomes, recurrent infections, secondary osteomyelitis, long-term effusions, flexion contractures, and joint ankylosis have been observed. ¹⁵

Conclusion

Septic arthritis secondary to Prevotella bivia is rare and can present a diagnostic dilemma, as demonstrated in the presented case. Although Prevotella infection is typically preceded by some insult to the joint, the patient presented above had no history of arthropathy or joint injury. Early consideration and diagnostic investigation of septic arthritis when patients present with acute or subacute signs and symptoms of underlying articular inflammation is essential for decreasing the likelihood of destruction and long-term disability in these patients. Review of previous cases suggest good outcomes following recognition and appropriate treatment.