Rapid Diagnosis of Septic Arthritis by Quantitative Analysis

Transcription

1 JOURNAL OF CLINICAL MICROBIOLOGY, Dec. 1978, p /78/ $02.00/0 Copyright C 1978 American Society for Microbiology Vol. 8, No. 6 Printed in U.S.A. Rapid Diagnosis of Septic Arthritis by Quantitative Analysis of Joint Fluid Lactic Acid with a Monotest Lactate Kit ITZHAK BROOK* AND GUIDO CONTRONI Infectious Disease and Clinical Microbiology Laboratory, Children's Hospital National Medical Center, George Washington University, Washington, D.C Received for publication 29 August 1978 The Monotest Lactate Kit (MLT) was compared with gas-liquid chromatography (GLC) for the rapid detection of septic arthritis. A total of 36 joint fluids were tested. Specimens were obtained from patients with septic arthritis (17 cases), inflammatory arthritis (18 cases), and degenerative arthritis (1 case). Specimens from 15 patients with bacterial arthritis had lactate levels above 65 mg/dl (mean, 318 mg/dl with the GLC method and 378 mg/dl with the MLT method). Three specimens from patients with gonococcal arthritis had levels that were not above 30 mg/dl (mean, 21 mg/dl with either the GLC or the MLT method). Patients with inflammatory or degenerative disease yielded levels lower than 65 mg/dl (mean, 48 mg/dl with the GLC method and 46 mg/dl with the MLT method). Both methods proved to be equally reliable in detecting septic arthritis, except for the gonococcal cases. Both methods are fast and easily adaptable to clinical laboratories; however, MLT was more definitive when quantitation was needed, required less fluid per specimen, and could be readily done at the bedside. The early and accurate diagnosis of septic arthritis is of great clinical importance. Differentiation of an infectious arthritis from a noninfectious inflammatory synovitis is a frequent diagnostic problem for physicians (12). Furthermore, synovial fluid analysis often fails to yield a diagnosis, despite careful bacteriological examination (10). Measurement of synovial fluid lactic acid concentrations in various pathological conditions have been attempted in the past (13). However, almost all of the data collected was related to patients suffering from noninfectious inflammatory processes (7). A small increase in the amount of lactic acid was noted in patients with rheumatoid arthritis (when measured under low oxygen tension) (9). Furthermore, in vitro studies revealed that bacterial endotoxins may cause an increase in the amount of synovial fluid lactate (3). Recent work done by various investigators has demonstrated that elevations of lactic acid in cerebrospinal fluid may indicate the presence of bacterial meningitis (1, 2, 4) and septic arthritis (I. Brook, M. J. Reza, S. M. Bricknell, R. Bluestone, and S. M. Finegold, Abstr. Annu. Meet. Am. Soc. Microbiol. 1977, C203, p. 69). These studies have shown that the measurement of lactic acid is very reliable in the differentiation between aseptic and bacterial meningitis, even in partially treated cases, and between septic and nonseptic arthritis, except for gonococcal cases. Gas-liquid chromatography (GLC) was used in previous studies (1, 2, 4) for the measurement of lactic acid levels. This method, although accurate, is not always available in small bacteriology laboratories. In our present study we evaluated a simplified, enzymatic method for the measurement of lactate levels of body fluids, using the Monotest Lactate Kit (MLT; Boehringer Mannheim Corp., Bio Dynamics Inc., Indianapolis, Ind.) (5). (This work was presented in part at the 78th Annual Meeting of the American Society for Microbiology, Las Vegas, Nev., May 1978.) MATERIALS AND METHODS Synovial fluid was obtained from patients with a diagnosis of untreated, acute monoarticular arthritis. Twenty-four of the patients were males, and 12 were females. Their ages ranged from 4 to 54 years; the average age was 32 years. The patients were divided into three major subgroups: septic, inflammatory, and degenerative arthritis, each of which was further subdivided into specific diagnostic entities. Group A: septic arthritis. Patients in group A had positive synovial fluid bacterial cultures. The patients with nongonococcal septic arthritis (14 cases) had leukocyte counts in the joint fluid ranging from 31,500 to 186,000 cells per mm;3 (mean, 98,600 cells per mm3), and their joint fluid glucose ranged from 5 to 32 mg/dl (mean, 22 mg/dl). The patients with gonococcal 676 Downloaded from on September 23, 2017 by guest

2 VOL. 8, 1978 septic arthritis (three cases) had leukocyte counts in their joint fluid ranging from 24,500 to 68,000 cells per mm3 (mean, 38,000 cells per mm3), and their glucose ranged from 8 to 42 mg/dl (mean, 20 mg/dl). Groups B and C: inflammatory and degenerative arthritis. Patients in groups B and C presented with an acute exacerbation of inflammatory or degenerative arthritis, with negative bacterial cultures. The leukocyte counts in their joint fluids ranged from 126 to 33,500 cells per mm3 (mean, 4,655 cells per mm'), and their joint fluid glucose ranged from 29 to 125 mg/dl (mean, 88 mg/dl). They had clinical and laboratory evidence of the following conditions: (i) rheumatoid arthritis (11) (12 patients); (ii) chronic inflammatory bowel disease (3 patients); (iii) acute gout and pseudogout (crystal proven; 2 patients); (iv), traumatic arthritis (patient with this diagnosis had acute trauma to the joint within 48 h before the tap and presented with joint effusion; 1 patient); (v) osteoarthritis (degenerative joint disease; 1 patient). The synovial fluid was obtained by direct puncture of the affected joints, using the aseptic technique. Specimens were placed in a sterile tube and frozen immediately at -20 C until analyzed. GLC lactic acid was measured as described previously (K. S. Bricknell, P. T. Sugihara, and I. Brook, Abstr. Annu. Meet. Am. Soc. Microbiol. 1976, C108, p. 44). After methylation, 10 1pl of the chloroform extract was injected into a stainless steel Resoflex column (OD, 6 feet by ' inch [ca. 1.8 m by 0.32 cm]; Gurrell Co., Pittsburgh, Pa.), using a thermal conductivity detector (Varian Aerograph, Sunnyvale, Calif.). Hehum carrier gas at 60 ml/min was used. The injector block temperature was 155 C, the column temperature was 145 C, and the detector block temperature was 160 C. MLT measurements were carried out following directions of the manufacturer (Boehringer Mannheim). The MLT test is based on the lactate dehydrogenasecatalyzed oxidation of lactate to pyruvate. During the oxidation of lactate, an equimolar concentration of nicotinamide adenine dinucleotide is produced, which is determined spectrophotometrically. The entire assay requires 15 min to complete. RESULTS Thirty-six patients were studied (Table 1). There were 17 patients in the septic arthritis group, including 3 with gonococcal arthritis, and 19 in the nonseptic arthritis group. There was no difference in the distribution of age and sex between the groups studied. Comparisons of lactic acid levels, obtained by both methods, were similar in the results. There was no statistical difference between the data obtained in all groups of patients. The lactic acid measurements are given in Table 1. All patients with gonococcal arthritis had lactic acid concentrations in the synovial fluid lower than 31 mg/dl with both methods. Patients with gram-negative bacillary infections also had lactic acid levels higher than 180 mg/dl with both methods. There were seven patients RAPID DIAGNOSIS OF SEPTIC ARTHRITIS 677 TABLE 1. Synovial fluid lactic acid concentration in acute monoarticular arthritis: comparison of GLC with MLT No. Avg lactic Range of of acid level lactic acid Diagnosis pa (mg/dl) with: (mg/dl) with: tients GLC MLT GLC MLT Bacterial (non gonococcal) Bacterial (gon ococcal) Inflammatory and degenerative with gram-positive coccal infections. In all of these, lactic acid concentrations were higher than 54 mg/dl. In the group of patients with nonseptic effusions, synovial lactate concentrations were all below 59 mg/dl. Statistical analysis with the Student t test showed that synovial lactic acid concentrations from patients with gram-negative bacilli and gram-positive coccal septic arthritis were significantly higher than those from both the gonococcal septic arthritis group and the nonseptic inflammatory and degenerative arthritis groups (P < 0.001). The distribution of the individual lactic acid values is shown in Table 2. There was no overlap between lactic acid values in the gram-negative bacillary and gram-positive coccal group, as opposed to the patients with gonococcal arthritis in whom lactic acid concentrations were uniformly lower than 30 mg/dl. When only lactic acid measurements were used, patients with gonococcal arthritis could not be differentiated from those with inflammatory and noninflammatory arthritis. DISCUSSION The data presented suggest that lactic acid measurements may clearly differentiate between septic arthritis, other than gonococcal arthritis, and other sterile inflammatory and noninflammatory conditions in the joints. Furthermore, elevation in the levels of lactic acid in the synovial fluid can alert physicians to the presence of bacterial infection in patients suffering from any of the types of chronic polyarthritis. The mechanism of lactic acid formation in the joints has been studied in the past. Studies of synovial membrane metabolism as reflected by oxygen and bicarbonate tension, ph, and lactic acid formation showed that decrements in oxygen and partial pressures in rheumatoid arthritis joint fluids were accompanied by a decrease in Downloaded from on September 23, 2017 by guest

3 678 BROOK AND CONTRONI TABLE 2. Synovial flu,id lactic acid concentration acid, which is converted to lactic acid, which is in acute monoarticular arthritis in the two methods a "metabolic blind alley" under anaerobic con- 36 patients ditions. Lactic acid concentrations in these stud- employed iwith Lactic acid ies of patients with rheumatoid arthritis were 40. level usually in the range of 15 to 55 mg/dl. Lactic Diagnosis Cof Age Sex (mg/dl) acid concentrations in bacterial inflammatory patiients (yr) with: arthritis have not been hitherto studied. Septic (17 cases) N. gonorrhoeae Staphylococcus aureus Pseudomonas aeruginosa Klebsiella pneumoniae Escherichia coli Proteus mirabilis Haemophilus influenzae Anaerobic grampositive cocci Candida albicans Inflammatory cases) Rheumatoid thritis (18 ar- Ulcerative colitis Crohn's disease Acute gout Traumatic ] GLC MLT In vitro experiments studying the effects of bacterial products on selected synovial fibroblast 3 25 M functions have been reported (13). Extracts of 30 M gram-negative bacteria applied to fibrobast cul- 21 M tures markedly increased hyaluronic acid pro F duction, glucose utilization, and lactate produc- 32 F tion. On the other hand, extracts of gram-posi- 8 M tive cocci (staphylococci and streptococci) and 28 M Neisseria gonorrhoeae had no stimulating ca M pabilities. These data correlate with the elevated 44 M lactic acid concentrations in patients with gram- 59 M negative bacillary arthritis reported here. They do not, however, explain the elevated synovial 1 63 F lactate which we noted in staphylococcal and 1 50 M other gram-positive coccal infections. However, 1 6 M since only bacterial products were used in the above experiments, the participation of other 2 47 F constituents of the whole bacteria may contrib- 64 M ute an additional stimulus of other unidentified bioactive materials which produce the increase in lactic acid. The lack of significant lactic acid elevation in gonococcal arthritis may signify the inability of bacterial products of this organism 2 68 M to cause the metabolic changes capable of pro- 49 M ducing excess lactate. 55 M Lactic acid measurements, therefore, appear 56 F to be a valuable diagnostic tool in the early 62 F differentiation between bacterial septic arthritis, 58 M except for gonococcal cases, and nonseptic ar- 70 M thritis before bacterial cultures are available. 64 F Lactic acid levels higher than 65 mg/dl with 58 M either the GLC or the MLT method should be 45 F considered as highly suggestive of the presence 60 M of an inflammatory process. Determination of 1 22 M synovial fluid lactic acid concentrations with 2 28 M MLT is a rapid, relatively simple, reproducible 39 F test, which could be done at the patient's bedside 57 F and provide the clinician with important clinical 1 20 M formation. Degenerative (1 case) Osteoarthritis 1 60 F ph and an increase in pco2 and lactic acid concentration (13). These changes signified the changeover of local tissues from mainly aerobic to largely anaerobic (glycolytic) metabolism. Other investigators have found an inverse relationship between lactic acid synovial levels and glucose (6, 8). Glucose is metabolized to pyruvic ACKNOWLEDGMENT We thank H. Tager for her assistance. J. CLIN. MICROBIOL. LITERATURE CITED 1. Bland, R. D., R. D. Lester, and J. P. Ries Cerebrospinal fluid lactic acid and ph in meningitis. Am. J. Dis. Child. 128: Brook, I., K. S. Bricknell, G. D. Overturf, and S. M. Finegold Measurement of lactic acid in cerebrospinal fluid of patients with infections of the central nervous system. J. Infect. Dis. 137: Buckingham, R. B., C. V. Custer, and P. F. Hoag The effect of bacterial products on synovial fibroblast function: hypermetabolic changes induced by Downloaded from on September 23, 2017 by guest

4 VOL. 8, 1978 RAPID DIAGNOSIS OF SEPTIC ARTHRITIS 679 endotoxin. J. Clin. Invest. 51: Controni, G., W. J. Rodriguez, C. Dean, S. Ross, W. Khan, and J. R. Puig Rapid diagnosis of meningitis by gas liquid chromatographic analysis of cerebrospinal fluid lactic acid. Clin. Proc. Child. Hosp. Natl. Med. Cent. 31: Controni, G., W. J. Rodriguez, J. M. Hicks, M. Ficke, S. Ross, G. Friedman, and W. Khan Cerebrospinal fluid lactic acid levels in meningitis. J. Pediatr. 91: Falchuk, K. H., E. J. Goetzl, and J. R. Kulka Respiratory gases of synovial fluids, an approach to synovial time circulatory metabolic imbalance in rheumatoid arthritis. Am. J. Med. 49: Goetzl, E., R. I. Rynes, and S. Stillman Abnormalities of respiratory gases in synovial fluid of patients with juvenile rheumatoid arthritis. Arthritis Rheum. 17: Lund-Olsen, K Oxygen tension in synovial fluids. Arthritis Rheum. 13: Roberts, J. E., B. D. MeLess, and G. P. Werley Pathways of glucose metabolism in rheumatic and nonrheumatoid synovial membrane. J. Lab. Clin. Med. 70: Ropes, M. W., and W. Bauer Synovial fluid changes in joint disease. Harvard University Press, Cambridge, Mass. 11. Ropes, M. W., G. A. Bennett, and S. Cobb Revision of diagnostic criteria from rheumatoid arthritis. Bull. Rheum. Dis. 9: Steinbrocker, O., and D. H. Neustadt Aspiration and injection therapy in arthritis musculoskeletal disorders. Harper & Row, Hagerstown. 13. Treuhalt, P. S., and D. J. McCarty Synovial fluid ph, lactate, oxygen and carbon dioxide partial pressure in various joint diseases. Arthritis Rheum. 14: Downloaded from on September 23, 2017 by guest

5 ERRATUM Rapid Diagnosis of Septic Arthritis by Quantitative Analysis of Joint Fluid Lactic Acid with a Monotest Lactate Kit ITZHAK BROOK AND GUIDO CONTRONI Infectious Disease and Clinical Microbiology Laboratory, Children's Hospital National Medical Center, George Washington University, Washington, D.C Vol. 8, no. 6, p. 676, Abstract, line 5: "15 patients" should read "14 patients." Page 676, column 2, line 20: "4 to 54" should read "6 to 70." Page 676, column 2, line 26: "synovial fluid bacterial cultures" should read "synovial fluid cultures." Page 677, Table 1, column 6: "84-972" should read " " Page 677, Table 1, colunm 2: "18" should read "19." Page 677, column 2, line 3: "54" should read "84." Page 677, column 2, ine 5: "59" should read "64." Page 678, Table 2, column 1: "Acute gout" should read "Acute gout and pseudogout." 559