Rheumatology 2001; 40: 112-113
© 2001 British Society for Rheumatology
Letters to the Editor |
Salmonella enteritidis infection in total knee replacement
Departments of Orthopaedics and
1 Rheumatology, Royal Bournemouth Hospital, Bournemouth, UK
SIR, Salmonella enteritidis infection of the joints is very rare and only a handful cases have been reported [1–3]. Non-typhoid salmonella infection is more common in Western countries because animals are carriers of the bacteria [4]. Immunosuppression is said to be a major contributing factor in the majority of these cases. We present a case of total knee replacement in which infection developed 8 yr after the original operation.
A 75-yr-old diabetic lady underwent total arthroplasty of the left knee in March 1990 for rheumatoid arthritis. Her postoperative recovery was uneventful, and her knee remained symptom-free for 8 yr. However, in February 1998 she was admitted with a painful, swollen left knee. This happened a week after an episode of diarrhoea and vomiting, which the patient attributed to a meal of fish and chips. She had been on oral steroids for several years (deflazacort). On admission she was febrile (38°C) and had a swollen and tender left knee. The blood tests showed a high white blood cell count (21.4x103/µl) and the erythrocyte sedimentation rate was 108 mm in the first hour. There was no growth from stool culture. Gram-negative bacilli grew from a blood culture and the knee aspirate showed growth of S. enteritidis (phage type 4) on enrichment culture. Although plain X-rays of the knee were unremarkable (Fig. 1
), bone scanning revealed increased technetium radioisotope uptake around the tibial and patellar prosthesis, suggestive of infection (Fig. 2). The patient received ciprofloxacin (500 mg b.d.) for 6 weeks, which controlled her symptoms well. She developed a further flare-up of the symptoms 15 months later and the knee aspirate again grew Salmonella species (09:G). She was given ciprofloxacin for 3 months, which made her symptom-free. Radiographs of the knee showed no changes suggestive of loosening of the implant or bone infection. No further recurrence of symptoms has been reported. We plan to treat her conservatively until she is asymptomatic, although further intervention in the form of removal of metalwork from her knee may have to be considered if the symptoms recur.
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Although haematogenous infection of a joint prosthesis can occur any time after surgery, Gram-negative organisms are rare as a cause of joint infection. S. choleraesuis and S. typhimurium are the most common species of salmonella causing joint infection [5]. Even in areas where salmonellosis is endemic, S. enteritidis is a rare cause of septic arthritis [1]. Diabetes mellitus, immunosuppressed states and malignancy are definite risk factors for the development of this infection. Infection of eggs and poultry was blamed for the development of infection in few of the early reports [2].
As a prosthetic joint is at risk of bacterial infection during an episode of bacteraemia, it is vital to confirm the diagnosis by growing the bacteria from a joint aspirate in order to differentiate true infection from reactive arthritis. Our patient gave a history suggestive of salmonella gastroenteritis, although this could not be confirmed by stool culture. However, there is no doubt that the infection in the present case occurred through the haematogenous route. The likelihood of peroperative contamination is very unlikely, as the patient presented 8 yr after surgery. Immunosuppression due to long-term steroid therapy for rheumatoid arthritis may have played a part in the development of infection in our patient. Protracted conservative treatment was justified as the virulence of the organism was low. Fluoroquinolones (ciprofloxacin, ofloxacin) possess pharmacological properties that are ideal for the treatment of such infections, because they have low minimum inhibitory and minimum bactericidal concentrations for most bone and joint pathogens [6]. Because the organisms persist in the synovial cavity, prolonged treatment is necessary for complete recovery.
This report is of interest not only because Gram-negative organisms are rare as a cause of septic arthritis but also because it highlights the role of bone scanning and microbiological testing in diagnosing an infected joint replacement when the X-ray is normal.
Notes
Correspondence to: S. Madan, Flat 2, Elmwood Court, 7–11 Laundry Road, Shirley, Southampton SO16 6AQ UK. 
References
- John R, Mathai D, Daniel AJ, Lalitha MK. Bilateral septic arthritis due to Salmonella enteritidis. Diagn Microbiol Infect Dis1993;17:167–9.[Medline]
- Kyle V, Chard M, Ramsey S, Cawston TE, Hazleman BE. Salmonella enteritidis causing joint sepsis. Clin Rheumatol1990;9:411–3.[Medline]
- Romero J, Schreiber A, Binswanger U. Late complications after total hip replacement in renal allograft recipients. Int Orthop1994;18:368–71.[Medline]
- Carlson DA, Dobozi WR. Haematogenous Salmonella typhi osteomyelitis of the radius. A case report. Clin Orthop Relat Res1994;308:187–91.
- Cohen JI, Bartlett JA, Corey GR. Extra-intestinal manifestations of salmonella infection. Medicine1987;66:349–88.[Medline]
- Waldvogel FA. Use of quinolones for the treatment of osteomyelitis and septic arthritis. Rev Infect Dis1989;11:1259–63.
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