Septic Arthritis due to Neisseria meningitidis in the Absence of Meningitis

Introduction Septic arthritis is an inflammation of a joint space usually secondary to a bacterial infection. The route of infection is usually hematogenous, however, it may occur through direct inoculation from an adjacent site of infected tissue or during trauma. Staphylococcus aureus is the most common organism, affecting 44% of patients, followed by streptococcal and other staphylococcal species. E. coli and Pseudomonas also have been described, but are more common in neonates and in people with immunodeficiency. N. gonorrhea presents mainly in young adults. Meningococcal arthritis associated with meningitis has been reported since the 19 century. Primary meningococcal arthritis is rare with only 1% being isolated from synovial fluid. Most cases usually involve the knee. This case is a female patient who presented with right elbow arthritis with N. meningitides as the infecting pathogen.


Introduction
Septic arthritis is an inflammation of a joint space usually secondary to a bacterial infection. 1The route of infection is usually hematogenous, however, it may occur through direct inoculation from an adjacent site of infected tissue or during trauma.Staphylococcus aureus is the most common organism, affecting 44% of patients, followed by streptococcal and other staphylococcal species.E. coli and Pseudomonas also have been described, but are more common in neonates and in people with immunodeficiency.N. gonorrhea presents mainly in young adults. 2eningococcal arthritis associated with meningitis has been reported since the 19 th century. 3Primary meningococcal arthritis is rare with only 1% being isolated from synovial fluid.Most cases usually involve the knee. 4This case is a female patient who presented with right elbow arthritis with N. meningitides as the infecting pathogen.

Case Report
A 46-year-old female patient presented to the emergency department with a 24-hour onset of painful swelling of the right elbow with decreased range of motion.She denied any recent febrile illness, headache, or sick contacts.She had no history of trauma to the elbow.In the emergency department, she had low grade fever of 100.6 o F. Physical examination of her right upper extremity revealed a minimal effusion, with swelling and warmth around the elbow.No ecchymosis or abrasion was noted.Her lateral epicondyle was tender to palpation.Neurological exam was intact and no meningismus was noted.Her skin examination was normal with no notable rash.
A complete blood count showed leukocytosis at 17,900 with 74% neutrophils.
She had an elevated sedimentation rate (56 mm/hr) and C reactive protein (7.1 mg/L).Plain film of the right elbow revealed a small anterior fat pad sign indicative of effusion but no fracture or dislocation (Figure 1).An arthrocentesis revealed 96,000 nucleated cells and 50,000 red blood cells, with 60% neutrophils and 20% bands but no crystals.Gram stain revealed innumerable white blood cells and few gram negative diplococci.
She underwent an arthrotomy with irrigation and debridement of the right elbow.Intraoperative cultures as well as synovial fluid cultures grew N. meningitides.Blood cultures taken prior to antibiotic administration remained negative.Human immunodeficiency virus antibody was negative and complement levels were normal.The patient received a four week course of ceftriaxone one gram daily.She had complete resolution and full range of motion of her elbow.

Discussion
Incidence of meningococcal disease is low, ranging from 2.5 to 6 per 100,000 in developing countries. 5N. meningitides most commonly presents as meningitis in 50% of patients, followed by meningococcemia.Less common presentations include pneumonia, epiglottitis, otitis media, conjunctivitis, urethritis, pericarditis, and arthritis. 6eningococcal arthritis occurs via direct inoculation to the synovium or a hypersensitivity reaction where an antigen antibody reaction results in a sterile effusion. 5It can present in three clinical scenarios.One presentation would be a complication of acute meningitis.It can lead to either a septic or aseptic arthritis, secondary to deposition of immune complexes.It also could be associated with chronic meningococcemia, a rare entity that presents with rash and fever, and leads to migratory arthritis or arthralgias.[6] A review of literature revealed 46 cases of patients with meningococcal joint infection without meningeal signs.Of those, only 19 patients had an isolated joint infection with 10 cases being children less than four years old.In addition, three other patients had an associated immune suppressive state: lupus, multiple myeloma, and leukemia.The remaining seven were healthy men with ages ranging from 50 to 60. 3 A multilingual review of literature revealed seven cases of females with an isolated joint infection (Table 1).9][10][11] Those cases easily can be misdiagnosed as disseminated gonococcus prior to final culture results.Neisseria gonorrhea is the most common cause of septic arthritis in sexually active young adults, with four times preponderance in females. 8It is difficult to separate the two Neisseria species on microscopy as both are morphologically indistinguishable. 11Differentiating the two species is important, especially in regards to Table 1.Multilingual review of literature resulting in seven cases of females with isolated joint infection.
antimicrobial prophylaxis of close contacts; airborne for meningococcus and sexual for gonococcus.
The knee joint is affected most commonly, followed by the ankle. 3,5The patient described in our report was immunocompetent and presented with elbow involvement which had not been described previously.The yield of culture specimens is highest from the synovial fluid (70 to 90%), followed by blood and pharynx.These numbers highlight the importance of performing an arthrocentesis to establish a diagnosis, preferably prior to antibiotic administration. 5reatment is challenging due to lack of evidence based literature.Intravenous penicillin or cephalosporins have been used with good outcomes.The duration of treatment varied from 7 to 42 days. 8Surgical debridement should be considered as part of the treatment plan due to the high rate of complications associated meningococcal arthritis where bone and joint destruction has been described.N. meningitides also may lead to serious systemic manifestations such as meningitis, pericardial effusion, ventricular enlargement, and acute respiratory distress.This is in contrast to N. gonorrhea that has been associated with only small damage to joint surfaces and has less frequent end organ complications.
Our case highlighted the systemic nature of N. meningitidis infection, causing disease in a native joint of an immunocompetent patient.The elbow being the infected joint is rare.Obtaining fluid or tissue culture prior to administration of antibiotics is critical for diagnosis.Surgical debridement should be an adjunct to antibiotic therapy.Microbiology support is essential to differentiate from N. gonorrhea, as approach and duration of treatment is affected.

Figure 1 .
Figure 1.A small anterior fat pad sign is indicative of effusion but no fracture or dislocation.