Scandinavian Journal of Rheumatology
ISSN: 0300-9742 (Print) 1502-7732 (Online) Journal homepage: http://www.tandfonline.com/loi/irhe20
Synovial Fluid Leukocytosis in Bacterial Arthritis vs. Reactive Arthritis and Rheumatoid Arthritis in the Adult Knee P. Kortekangas, H. T. Aro, J. Tuominen & A. Toivanen To cite this article: P. Kortekangas, H. T. Aro, J. Tuominen & A. Toivanen (1992) Synovial Fluid Leukocytosis in Bacterial Arthritis vs. Reactive Arthritis and Rheumatoid Arthritis in the Adult Knee, Scandinavian Journal of Rheumatology, 21:6, 283-288 To link to this article: http://dx.doi.org/10.3109/03009749209099243
Published online: 12 Jul 2009.
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Date: 19 January 2016, At: 01:10
Synovial Fluid Leukocytosis in Bacterial Arthritis vs. Reactive Arthritis and Rheumatoid Arthritis in the Adult Knee P. Kortekangas*, H. T. Aro*, J. Tuominen**, A. Toivanen*** Departments of Surgery*, Biostatistics**, and Medicine and Medical Microbiology***, University of Turku, Turku, Finland
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Kortekangas P, Aro H T , Tuorninen J , Toivanen A . Synovial Fluid Leukocytosis in Bacterial Arthritis vs. Reactive Arthritis and Rheumatoid Arthritis in the Adult Knee. Scand J Rheumatol 1992; 21: 283-288.
In this comparative analysis of laboratory data, we examined the characteristics of synovial fluid leukocytosis in eighty adult patients with bacterial arthritis, reactive arthritis o r rheumatoid arthritis of the knee joint. Synovial fluid leukocyte count and the pcrccntage of polyrnorphonuclear cells seemed to perform well as a discriminator between bacterial infection and acute flare of the underlying disease in patients with rheumatoid arthritis. In contrast, there were n o definite difference in the intensity of synovial tluid leukocytosis between patients with bacterial arthritis caused by living bacteria and patients with reactive arthritis probably caused hy bacterial antigens.
Key words: joint fluid, infectious arthritis, bacterial arthritis.
Suspicion of a bacterial joint infection is a diagnostic emergency. The key to the diagnosis is immediate aspiration and proper analysis of the synovial fluid. The only definitive diagnostic test is either the demonstration of bacteria by Gram stain or isolation of bacteria from the synovial fluid culture. Unfortunately, the Gram stain does not show any organism in approximately 40 per cent of cases. The rate of negative stain varies with the microbial agent causing the infectious arthritis (1). If the Gram stain is negative, clinical decisions must rely on indirect laboratory evidence suggesting bacterial etiology. Bacterial arthritis usually causes intense synovial fluid leukocytosis, with 50, 000 to 200, 000 cells/mm' and usually over 90% polymorphonuclear leukocytes (1). Some patients with bacterial arthritis may show a less intense synovial leukocytosis (2, 3 , 4) when the synovial fluid finding may overlap with those of crystal-induced arthritides and rheumatoid arthritis (2). A major clinical problem is related to the differential diagnosis between bacterial arthritis and reactive arthritis. The clinical presentations of the two disease states frequently are the same. Reactive arthritis develops as a late complication after certain infections, especially in susceptible people positive for HLA B27. The combination of culture-negative arthritis, positive serology for a prePirkko Kortekangas, Department of Surgery, University of Turku, SF-20520 Turku, Finland Received 22 April 1992 Accepted 30 September 1992
ceding infection and microbial antigens in synovial cells has been demonstrated to follow Yersinia enterocolitica, Salmonella enteritidis and Salmonellu typhirnurium gastrointestinal infections, and Chlamydia trachomatis urogenital infection ( 5 , 6, 7). None of the earlier large-scale studies of synovial fluid findings in bacterial arthritis have included a control group of patients with reactive arthritis. In addition, most of the previous studies have been based on analyses of heterogeneous patient populations including adult and pediatric patients and patients with different joint affections. In this study, we sought characteristic synovial fluid findings in bacterial arthritis of the adult knee as compared with those found in reactive arthritis and rheumatoid arthritis. Patients and methods
Synovial fluid findings of 80 adult patients treated in our institution for acute arthritis of the knee joint (Table I and 11) were analyzed. The results were analyzed retrospectively in 72 patients. Eight patients were included in a prospective clinical trial o n bacterial arthritis. All the patients fulfilled the following criteria for inclusion in the study: (a) age of 16 years or older, (b) no penetrating joint injury, (c) no history of knee joint surgery within one year, (d) no prosthetic knee surgery, and (e) the joint was aspirated on admission and the leukocyte count of the synovial fluid was recorded. All patients with rheumatoid arthritis fulfilled the American College of Rheumatology (ACR) criteria for classic or definite RA (8). 283
Kortekangas et al. Table I. Characteritics of patients with bacterial and reactive arthritis of the knee joint Bacterial arthritis (n=20)*
Probable bacterial arthritis (n=13)
Reactive arthritis (n=20)
9: 11
8: 5
6: 14
57 (21-95)
60 (17-79)
15 (75%)
9 (69%)
Gender (F:M) Median age (range) (years) Symptoms less than a week
I%)
Fever (%) over 37.5"C
16 (80%)
10 (50%)
8 (62%)
13 (65%)
11.6 (4.5-32.5)
10.0 (4.6-16.5)
9.9 (7.3-16.1 1
Median (range) erythrocyte sedimentation rate mm/h**
78 (16145) (n=19)
59 (20-128) (n=11)
79 (27-121) (n=18)
Median (range) C-reactive protein g/l**
125 (47-266) (n=12)
89 (5-160) (n=10)
129 (32-280) (n=15)
Median (range) peripheral leukocytesx 109/1
Downloaded by [NUS National University of Singapore] at 01:10 19 January 2016
36 (17-SO)***
* Eight patients with underlying rheumatoid arthritis not included (see Table 2) ** The number of patients studied shown in parenthesis *** p
ISSN: 0300-9742 (Print) 1502-7732 (Online) Journal homepage: http://www.tandfonline.com/loi/irhe20
Synovial Fluid Leukocytosis in Bacterial Arthritis vs. Reactive Arthritis and Rheumatoid Arthritis in the Adult Knee P. Kortekangas, H. T. Aro, J. Tuominen & A. Toivanen To cite this article: P. Kortekangas, H. T. Aro, J. Tuominen & A. Toivanen (1992) Synovial Fluid Leukocytosis in Bacterial Arthritis vs. Reactive Arthritis and Rheumatoid Arthritis in the Adult Knee, Scandinavian Journal of Rheumatology, 21:6, 283-288 To link to this article: http://dx.doi.org/10.3109/03009749209099243
Published online: 12 Jul 2009.
Submit your article to this journal
Article views: 40
View related articles
Citing articles: 6 View citing articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=irhe20 Download by: [NUS National University of Singapore]
Date: 19 January 2016, At: 01:10
Synovial Fluid Leukocytosis in Bacterial Arthritis vs. Reactive Arthritis and Rheumatoid Arthritis in the Adult Knee P. Kortekangas*, H. T. Aro*, J. Tuominen**, A. Toivanen*** Departments of Surgery*, Biostatistics**, and Medicine and Medical Microbiology***, University of Turku, Turku, Finland
Downloaded by [NUS National University of Singapore] at 01:10 19 January 2016
Kortekangas P, Aro H T , Tuorninen J , Toivanen A . Synovial Fluid Leukocytosis in Bacterial Arthritis vs. Reactive Arthritis and Rheumatoid Arthritis in the Adult Knee. Scand J Rheumatol 1992; 21: 283-288.
In this comparative analysis of laboratory data, we examined the characteristics of synovial fluid leukocytosis in eighty adult patients with bacterial arthritis, reactive arthritis o r rheumatoid arthritis of the knee joint. Synovial fluid leukocyte count and the pcrccntage of polyrnorphonuclear cells seemed to perform well as a discriminator between bacterial infection and acute flare of the underlying disease in patients with rheumatoid arthritis. In contrast, there were n o definite difference in the intensity of synovial tluid leukocytosis between patients with bacterial arthritis caused by living bacteria and patients with reactive arthritis probably caused hy bacterial antigens.
Key words: joint fluid, infectious arthritis, bacterial arthritis.
Suspicion of a bacterial joint infection is a diagnostic emergency. The key to the diagnosis is immediate aspiration and proper analysis of the synovial fluid. The only definitive diagnostic test is either the demonstration of bacteria by Gram stain or isolation of bacteria from the synovial fluid culture. Unfortunately, the Gram stain does not show any organism in approximately 40 per cent of cases. The rate of negative stain varies with the microbial agent causing the infectious arthritis (1). If the Gram stain is negative, clinical decisions must rely on indirect laboratory evidence suggesting bacterial etiology. Bacterial arthritis usually causes intense synovial fluid leukocytosis, with 50, 000 to 200, 000 cells/mm' and usually over 90% polymorphonuclear leukocytes (1). Some patients with bacterial arthritis may show a less intense synovial leukocytosis (2, 3 , 4) when the synovial fluid finding may overlap with those of crystal-induced arthritides and rheumatoid arthritis (2). A major clinical problem is related to the differential diagnosis between bacterial arthritis and reactive arthritis. The clinical presentations of the two disease states frequently are the same. Reactive arthritis develops as a late complication after certain infections, especially in susceptible people positive for HLA B27. The combination of culture-negative arthritis, positive serology for a prePirkko Kortekangas, Department of Surgery, University of Turku, SF-20520 Turku, Finland Received 22 April 1992 Accepted 30 September 1992
ceding infection and microbial antigens in synovial cells has been demonstrated to follow Yersinia enterocolitica, Salmonella enteritidis and Salmonellu typhirnurium gastrointestinal infections, and Chlamydia trachomatis urogenital infection ( 5 , 6, 7). None of the earlier large-scale studies of synovial fluid findings in bacterial arthritis have included a control group of patients with reactive arthritis. In addition, most of the previous studies have been based on analyses of heterogeneous patient populations including adult and pediatric patients and patients with different joint affections. In this study, we sought characteristic synovial fluid findings in bacterial arthritis of the adult knee as compared with those found in reactive arthritis and rheumatoid arthritis. Patients and methods
Synovial fluid findings of 80 adult patients treated in our institution for acute arthritis of the knee joint (Table I and 11) were analyzed. The results were analyzed retrospectively in 72 patients. Eight patients were included in a prospective clinical trial o n bacterial arthritis. All the patients fulfilled the following criteria for inclusion in the study: (a) age of 16 years or older, (b) no penetrating joint injury, (c) no history of knee joint surgery within one year, (d) no prosthetic knee surgery, and (e) the joint was aspirated on admission and the leukocyte count of the synovial fluid was recorded. All patients with rheumatoid arthritis fulfilled the American College of Rheumatology (ACR) criteria for classic or definite RA (8). 283
Kortekangas et al. Table I. Characteritics of patients with bacterial and reactive arthritis of the knee joint Bacterial arthritis (n=20)*
Probable bacterial arthritis (n=13)
Reactive arthritis (n=20)
9: 11
8: 5
6: 14
57 (21-95)
60 (17-79)
15 (75%)
9 (69%)
Gender (F:M) Median age (range) (years) Symptoms less than a week
I%)
Fever (%) over 37.5"C
16 (80%)
10 (50%)
8 (62%)
13 (65%)
11.6 (4.5-32.5)
10.0 (4.6-16.5)
9.9 (7.3-16.1 1
Median (range) erythrocyte sedimentation rate mm/h**
78 (16145) (n=19)
59 (20-128) (n=11)
79 (27-121) (n=18)
Median (range) C-reactive protein g/l**
125 (47-266) (n=12)
89 (5-160) (n=10)
129 (32-280) (n=15)
Median (range) peripheral leukocytesx 109/1
Downloaded by [NUS National University of Singapore] at 01:10 19 January 2016
36 (17-SO)***
* Eight patients with underlying rheumatoid arthritis not included (see Table 2) ** The number of patients studied shown in parenthesis *** p
