A rare case of primary meningococcal knee arthritis
A 60-year-old man presented to the emergency department complaining of severe pain in the left knee joint for last two days, which was also accompanied by swelling, warmth, and tenderness. The severity of the pain and the joint stiffness was severe enough to restrict him from walking or even bending the knee joint. Although none of the other joints were affected this severe, he had visited the outpatient department few months back, complaining mild-to-moderate pain in multiple joints. The intensity of the pain was consistently increasing for the past two weeks and there was no relief even after taking multiple doses of over-the-counter pain relievers. Although he was a well-built person, he seemed to be very weak and dehydrated; may be due to decreased appetite.
The most likely diagnosis of this presentation is
- Disseminated gonococcal disease
- Knee arthritis/Gonarthrosis
Primary meningococcal arthritis (PMA) represents an uncommon form of septic arthritis caused by N. meningitides that affects as little as 1% of meningococcal infections.1, 2 Meningococcal arthritis prominently affects larger joints like knee and elbow joints. It may be often linked to history or on-going upper respiratory infections (50–55% ) or psoriasis and usually doesn’t show other signs of meningococcal disease such as meningitis, fever, rash, and hemodynamic instability.3,1 Septic arthritis is caused by variety of other microorganisms, including Staphylococcus aureus, which accounts for almost 44% of cases, Escherichia coli, Pseudomonads and N. gonorrhea which is the most common cause in adults.2 Studies have also indicated the role of low socioeconomic status, drug abuse, weak immunity and history of trauma in the development of septic arthritis.1, 2 Inappropriate diagnosis and/or management may lead to local destruction of the joint and peripheral spread of infection. Thus, septic arthritis is considered as a medical emergency and needs prompt diagnosis and effective treatment to avoid further complications. 2
Patient had a history of type II diabetes, but was not on any anti-diabetic medications until he diagnosed with retinitis few months back. He also recollected a history of an accident that had injured his both the knees and he was on bed rest for almost a week. He was recently diagnosed with high blood pressure and elevated lipids.
Examinations and Laboratory Investigations
A physical examination clearly showed the signs of arthritis, including swollen, reddened, and tender knee joint. Imaging studies showed an effusion of the synovial fluid, inflamed joint-lining, and loss of cartilage causing degenerative changes in the joint. Microscopic assessment of the synovial fluid from the diseased knee revealed the presence of gram-negative diplococci (which is further identified as N. meningitides) that indicated PMA. Blood examinations ruled out the increased levels of white blood cells (WBCs), and sodium (due to dehydration). Urine analysis showed an increased levels of albumin and urine protein indicating diabetic nephropathy.
Immediately after the hospitalization, intravenous injection of ampicillin/sulbactam (2:1, w/w ratio; 5 g, four times a day) was administered, and continued for 18 days. Insulin detemir and a special (calorie-limited) diet plan was considered as a part of the treatment regimen to manage diabetes. An electrolyte replenishment was undertaken to overcome the dehydration. A non-steroidal anti-inflammatory drug, was given to relieve the local pain and inflammation. The severity of symptoms decreased gradually with the treatment for 1-2 weeks and movement of the knee was significantly improved. Reexamination of the synovial culture (after two weeks of hospitalization) turned out to be negative for meningococcus.
Although PMA is uncommon, immunocompromised patients have a greater risk of developing this disease.1 Infection of N. Meningitidis is supposed to affect almost 5 million cases per year across the world, among which, about 10% of cases are estimated to develop arthritis complications. In this case, the patient did not show any symptoms of meningococcemia and blood culture/sputum analysis turned out to be negative, therefore the possibility of having meningococcemia was eliminated. It is important to begin an appropriate antibiotic regimen (first-line treatment) to treat meningococcal arthritis at an early stage to avoid further complications like degenerative damage.4 Since most of the septic arthric cases have gram-positive organisms as an underlying cause, the most appropriate first-line antibiotic choice would be penicillin or first-generation cephalosporin. However, if Neisseria gonorrhoeae is suspected, a third-generation cephalosporin is the recommended choice. Moreover, in case of methicillin-resistant S. aureus or opportunistic infection, vancomycin is preferred. Penicillin administered as an intravenous injection is the smart choice to treat PMA and other forms of meningococcal infection. After antibiotics, aggressive open irrigation of the diseased joint is the recommended therapy for septic arthritis. Further, considering the meningococcal conjugate vaccine as a preventive measure may play an important role in the disease management.2
Since PMA can be mistakenly diagnosed as a disseminated gonococcal disease, assessment of the synovium and blood cultures is important to rule out the cause of septic arthritis. Identification of underlying cause helps the experts to design the most effective treatment regimen at an early stage of the disease.
Michel M D, Kao L W, and Sloan B K. Primary Meningococcal Arthritis Leading to Neisseria Meningitidies Purpura Fulminans. West J Emerg Med. 2013 Mar; 14(2): 165–167.
Harwood M I, Womack J, and Kapur R. Primary Meningococcal Arthritis. J Am Board Fam Med January-February 2008 vol. 21 no. 166-69.
Andersson S, Krook A. Primary meningococcal arthritis. Scand J Infect Dis. 1987;19(1):51-4.
Nihonyanagi S, Sunakawa K, Cui L, et al. A very rare case of primary meningococcal arthritis in an adult male. Clin Case Rep. 2015 Feb;3(2):76-80.