A Rare Case Of Joint Infection Due To Raoultella Planticola
Abstract
Raoultella planticola, a rare gram-negative bacterium, was previously associated with the genus Klebsiella. There are two known species of Raoultella, Raoultella planticola and Raoultella ornithinolytica responsible for numerous infections including cystitis, pneumonia, and bacteremia. To date, only one other case of joint or bone infection due to Raoultella planticola has been reported. Evolution was favorable after arthroscopic lavage and antibiotic therapy with fluoroquinolones. We describe the first case of septic arthritis due to Raoultella planticola involving a native knee joint following synovectomy during arthroscopy.
Introduction
Post-surgical knee infections are uncommon but when they occur should be monitored very closely. Patients who undergo arthroplasty and receive an artificial knee versus patients who undergo arthroplasty in an attempt to repair the knee are said to be at higher risk for developing infections. This can be explained by the simple fact that the normal healthy functional immune system does not react the same way with the artificial knee vs the anatomical knee, leaving the artificial knee vulnerable for bacteria to adhere to it and cause infection at a rapid rate. Individuals that pose a higher risk for knee replacement surgery are typically ones that are obese, suffer from diabetes, encounter common urinary tract infections, or have rheumatoid arthritis. In addition, individuals that smoke, have had prior surgeries or been administered corticosteroids are vulnerable for developing infections.
The most common knee infections are from the bacteria Staphylococcus aureus and Streptococcus species. However, it should also be noted that although uncommon, other bacteria can cause knee infections. Uncommonly, Raoultella Planticola, a gram-negative bacterium pathogen found in soil, plant, and water settings. Individuals that are immunocompromised are more vulnerable to Raoultella Planticola. This is significant because it gives rise to a variety of infections such as gastrointestinal infections, urinary tract infections, and particularly, joint infections. Here, we report the case of a 77-year-old man who had septic arthritis due to Raoultella planticola involving a native knee joint following synovectomy during arthroscopy. To the best of our knowledge, no other case of bone or joint infection has occurred due to Raoultella planticola in the United States.
Case Report
A 77-year-old man with a past medical history of: infected prosthetic knee joint, right knee arthroplasty, left knee arthroplasty total revision, left knee arthroplasty total revision stage 1, inflammatory arthritis, infected prosthetic knee joint, diabetes mellitus and obesity presented to his primary care provider with inflamed left knee pain. Patient was alert and oriented and in apparent distress with severe pain. Upon referral to orthopedic surgery, patient was treated for left knee arthroplasty during arthroscopic exploration. Patient had several elevated lab values indicating infection including white blood cell count of 11K/ul (reference range 4.2-9.1 K/ul) C-Reactive Protein (CRP) of 264.9 mg/L (reference range <5.0 mg/L) and erythrocyte sedimentation rate of 109mm/hr (reference range 0-22 mm/hr.). Due to the infected prosthetic knee joint, a removal of infected left total knee arthroplasty with placement of articulating antibiotic spacer was performed. Patient was then admitted at hospital for inpatient stay. Upon admission, DVT prophylaxis at inpatient stay with acetylsalicylic acid was administered. Patient received peripherally inserted central catheter, 6 weeks of intravenous and oral Vancomycin 1,500 mg. Patient was discharged given IV antibiotics and scheduled for follow up visit in six weeks with primary care physician. Patient returned to orthopedic surgeon for follow up visit six weeks after arthroscopy for checkup after antibiotic spacer procedure was performed. Patient had elevated C-reactive protein level at 10 mg/L and elevated erythrocyte sedimentation rate of 50 mm/hr. Upon examination, patient’s wound healed, and an aspiration of left knee was attempted but there was no drainage available. Patient was administered antibiotic for two weeks, with repeat tests of C-reactive protein and erythrocyte sedimentation rate to follow.
Two weeks later, an anaerobic/aerobic culture with gram staining was ordered and the results indicated no anaerobic growth but confirmed 1+ or few Raoultella planticola. Patient had significant lymphedema and drainage from left leg; purulence was drained and cultured, and patient underwent a stage 1 spacer. A week later, patient presented with a severity of 7/10, increasing pain with weight bearing and activity, his pain interfered with activities of daily living, decreased mobility, passive range of motion, pain with functional disability, stiffness, left-knee joint due to septic arthritis. Infectious Disease was consulted for suspected Raoultella planticola prosthetic left knee infection. A left knee arthroplasty revision stage 1 procedure was later performed that same day. One day post-operation, patient’s wound was drained, and he continued to have poor knee mobility. Patient was administered high dose intravenous Levofloxacin 750mg/150mL every 24 hours for six weeks. Two days post operation, patient was on wound vac at upper part of left lower leg and physical exam revealed arthralgia and shortness of breath. One-week post-operation, patient’s CRP level was 131.7 mg/L while 2 weeks post-operation the patient’s CRP was 48.7 mg/L. Patient was given Xarelto for deep vein thrombosis prophylaxis and was placed in Long Term Acute Care (LTAC). Patient was scheduled for another follow up visit with orthopedic surgeon in 4-6 weeks. Patient received physical therapy daily. Patient was discharged three weeks after admission to LTAC and sent to a nursing home for further treatment.
Discussion
Raoultella planticola is a gram-negative bacterium that first emerged in the late 1900’s as Klebsiella planticola but was later renamed as Raoultella planticola in 2001. Raoultella planticola, from the genus Raoultella, is a potentially fatal opportunistic bacterium rarely involved in clinical infections and found in environments containing soil, plant, and water. Other potential sources of infection come from enteric translocation and invasive medical procedures.
This facultative anaerobic bacterium is most commonly found in cases of pneumonia, cystitis, urinary tract infections, gastrointestinal infections, and bacteremia. Of these cases, numerous reports have been documented regarding in relation to infection due to Raoultella planticola. There have been numerous cases with Raoultella planticola involving cystitis. However, the case presented here is currently the only reported case of joint infection due to Raoultella planticola involving a knee joint during arthroscopy. The patient in this case was at a higher risk for developing an infection as this was an obesely diabetic individual with a prior extensive surgical history including several arthroplasties.
Several lab tests were compiled to evaluate the spectrum of antibiotics that work best in this case. The evaluations of blood cultures made it apparent that Raoultella planticola was susceptible to a variety of antibiotics, specifically cefepime, ertapenem, levofloxacin, meropenem, and piperacillin – tazobactam. Simultaneously, it was also resistant against beta-lactams, ampicillin, sulbactam, cephazolin, ceftriaxone, gentamicin and trimethoprim-sulfamethoxazole.
Bonnet et al. reported the first definitive case for a joint infection due to Raoultella planticola following synovectomy and intra-articular injection of corticosteroid during arthroscopy. Interestingly, Raoultella planticola was susceptible to beta lactams and all other antibiotics tested. Results were confirmed through synovial fluid collection and mass spectrometry while the results pertaining to this case were validated via blood cultures, lab tests, and Acid-Fast Bacteria (AFB) staining.
Raoultella infections are usually treated with beta-lactams; however, in the present case, Levofloxacin, a fluoroquinolone was introduced for 6 weeks. Rapid improvement was observed. Patient was monitored for length of antibiotic duration and further discharged to a nursing home for follow-up care. The patient is stable and there are no signs of recurring infection. Raoultella planticola is becoming a more common environmental bacterium, new cases of bone and/or joint infection should be expected in the future, especially in patients with foreign bodies, such as immunocompromised patients and joint prosthesis.
