CASE REPORT * ETUDE DE CAS
Anaerobic vertebral osteomyelitis Jamin Feng, MD; Thomas W. Austin, MD, FRCPC H
ematogenous vertebral osteomyelitis has been considered a monomicrobial infection. Blood culture is usually sufficient to identify organisms for treatment.' This case report illustrates the need for fine-needle aspiration to obtain samples for anaerobic culture when treatment chosen on the basis of blood culture results fails. It is only the second reported case of hematogenous vertebral osteomyelitis caused by Bacteroides fragilis; previous cases of anaerobic vertebral osteomyelitis have been almost exclusively secondary to contiguous infection, notably decubitus ulcers.2
Case report A 68-year-old man presented with a 5-day history of fever, diaphoresis and intermittent chills. An empiric trial of erythromycin, 500 mg orally four times a day, was begun 2 days before presentation but had no effect. The patient denied bony pain or any other symptoms to suggest a focus of infection. His temperature was 38°C. Deep palpation revealed tenderness in the right upper qudrant. His prostate was normal; his stool was positive for occult blood. There were no further significant findings at that time. The patient's leukocyte count was 5.4 X 109/L (65% neutrophils, 21% lymphocytes, 14% band cells and 1+ toxic granulations), the blood hemoglobin level 138 g/L and the platelet count 67 X 109/L. The zeta sedimentation rate (ZSR) was 0.73 (normally 0.4 to 0.54). Urinalysis gave normal results; culture results of urine were also normal. Chest roentgenography, including a lateral view, showed no bony abnormalities. Cholelithiasis without biliary obstruction was found on ultrasound. The day after presentation intravenous therapy with ampicillin (1 g every 6 hours), metronidazole
(500 mg every 8 hours) and tobramycin (80 mg every 8 hours) was started. Blood samples taken on admission grew Proteus mirabilis in both aerobic and anaerobic bottles, which were subsequently discarded. Ogilvie's syndrome with colonic distention to the splenic flexure developed on the third day. No abscesses were seen on computed tomography (CT) of the abdomen. On the same day the patient complained of thoracic back pain. A bone scan and an indium- 111-labelled leukocyte scan showed increased uptake at the 10th and 1 1th thoracic vertebrae and in the intervening disc space. A presumptive diagnosis of vertebral osteomyelitis secondary to P. mirabilis was made; the patient received ampicillin, 6 g/d intravenously for 3 weeks, and then amoxicillin, 1500 mg/d orally for 3 weeks. The platelet count returned to normal, and the colonic distention resolved with conservative therapy. Seventeen days after admission colonoscopy demonstrated diverticulosis. The patient's fever subsided, and he remained asymptomatic until the sixth week of therapy, when his thoracic back pain recurred. He had tenderness with gibbus formation at the 10th thoracic vertebra. His leukocyte count was 8.2 x 109/L with a normal differential count. One week later the ZSR was 0.64. Plain x-ray films showed loss of the 10th thoracic disc space and vertebral compression at that level. In addition, there was sclerosis from the 7th to the 11th thoracic vertebrae. A CT scan revealed soft-tissue swelling anterior to the lower thoracic vertebrae. A sample obtained through fine-needle aspiration of the 10th thoracic disc space grew B. fragilis positive for j-lactamase in anaerobic culture. No other organisms were identified. Cultures were negative for tubercle bacilli, and cytologic examination showed no signs of malignant disease. After 3 weeks of intravenous therapy with cefa-
Dr. Feng is a resident in internal medicine, University of Western Ontario, London, Ont., and Dr. Austin is infectious diseases consultant, Victoria Hospital, London, Ont.
Reprint requests to: Dr. Thomas W. Austin, Infectious diseases consultant, Victoria Hospital, PO Box 5375, London, ON N6A 4G5 132
CAN MED ASSOC J 1991; 145 (2)
LE 1S JUILLET 1991
zolin, 1 g every 8 hours, and metronidazole, 500 mg every 8 hours, the regimen was changed to oral therapy with amoxicillin-potassium clavulanate, 500 and 125 mg respectively every 8 hours for 3 months. The patient remained afebrile, and there was no further progression of the vertebral compression.
Comments We suspect that our patient initially had polymicrobial bacteremia (likely of colonic origin) that went unnoticed because the blood cultures were discarded after isolation of P. mirabilis. His initial response to the ampicillin may have represented eradication of this more virulent organism, the subsequent deterioration representing the slower-acting B. fragilis infection. B. fragilis has been associated with osteomyelitis in various locations,2 but the first report of its association with hematogenous vertebral osteomyelitis was not until 1979.3 A MEDLINE search failed to produce cases reported since then. The implication of multiple organisms in hematogenous vertebral osteomyelitis is rare; infection of the urinary tract was the cause in one case.3 Our patient had no evidence of a urinary source of infection, and B. fragilis would be a rare urinary pathogen.4 This case demonstrates the importance of fineneedle aspiration of the intervertebral disc space if antimicrobial therapy based solely on blood culture results is inadequate. Failure of therapy should be suspected with recurrent back pain or radiographic evidence of progression. In addition, a decrease in the erythrocyte sedimentation rate to half or less than half of the pretherapy rate may indicate successful treatment.3 Fine-needle aspiration of the thoracic spine is a relatively safe procedure - a pneumothorax was the sole complication of 12 aspirations in a recent series.5 Anaerobic culture should be carried out routinely on all aspirates.
References 1. Sapico FL, Montgomerie JZ: Vertebral osteomyelitis. Dis Clin North Am 1990; 4: 539-550
Infect
2. Lewis RP, Sutter VL, Finegold SM: Bone infections involving anaerobic bacteria. Medicine 1978; 57: 279-298 3. Sapico FL, Montgomerie JZ: Pyogenic vertebral osteomyelitis: report of nine cases and review of the literature. Rev Infect Dis 1979; 1: 754-775 4. Siroky MB, Moylan RA, Austen G et al: Metastatic infection secondary to genitourinary tract sepsis. Am J Med 1976; 61:
35 1-360 5. El-Khoury GY, Terepka RH, Mickelson MR et al: Fine-needle aspiration biopsy of bone. J Bone Joint Surg [Am] 1983; 65: 522-525 JULY 15, 1991
Conferences continued from page 129 Oct. 2-4, 1991: Canadian Psychiatric Association 41 st Annual Meeting Saskatoon Inez Hoey, manager, Administrative Services, Canadian Psychiatric Association, 204-294 Albert St., Ottawa, ON KIP 6E6; (613) 234-2815, fax (613) 234-9857 Oct. 4, 1991: Clinical Hyperbaric and Diving Medicine (sponsored by the Hyperbaric Department, Toronto Hospital, and the Department of Anaesthesia, University of Toronto) Toronto General Division, Toronto Hospital Dr. G.H. Koch, CCRW G-821, 200 Elizabeth St., Toronto, ON M5G 2C4; (416) 340-4131, fax (416) 340-3698 Oct. 5, 1991: Canadian Council on Smoking and Health Annual Meeting Ottawa Andree Dumulon, national coordinator, Canadian Council on Smoking and Health, 400-1565 Carling Ave., Ottawa, ON K1Z 8R1; (613) 722-3419, fax (613) 725-9826 Du 9 au 11 oct. 1991 : Colloque international promouvoir la sante en francophonie - Au dela des cultures: des outils a partager (sous le parrainage du ministere de la Sante et des Services sociaux du Quebec) H6tel Bonaventure Hilton, Montreal Association pour la sante publique du Quebec, 3958, rue Dandurand, Montreal, QC HIX IP7; (514) 593-9939, fax (514) 725-2796
Oct. 23-26, 1991: American Medical Writers Association 51 st Annual Conference - World Class: Worldwide Biomedical Communications Royal York Hotel, Toronto American Medical Writers Association, 9650 Rockville Pike, Bethesda, MD 20814; (301) 493-0003 Nov. 1-2, 1991: Women, Food and Weight - New Perspectives 519 Church Street Community Centre, Toronto National Eating Disorder Information Centre, 200 Elizabeth St., Ste. CW1-328, Toronto, ON M5G 2C4; (416) 340-4156 Nov. 24-27, 1991: 4th Annual OPTIMA Conference Building Bridges to Well-being Radisson Hotel, Toronto Patti Etkin, conference coordinator, Donwood Institute, 175 Brentcliffe Rd., Toronto, ON M4G 3ZI; (416) 425-3930, fax (416) 425-7896 Dec. 11-15, 1991: American Back Society Fall Symposium on Back Pain San Francisco Marriott Hotel Dr. Aubrey A. Swartz, executive director, American Back Society, Ste. 401, 2647 E 14th St., Oakland, CA 94601; (415) 536-9929, fax (415) 536- 1812 CAN MED ASSOC J 1991; 145 (2)
133
Anaerobic vertebral osteomyelitis Jamin Feng, MD; Thomas W. Austin, MD, FRCPC H
ematogenous vertebral osteomyelitis has been considered a monomicrobial infection. Blood culture is usually sufficient to identify organisms for treatment.' This case report illustrates the need for fine-needle aspiration to obtain samples for anaerobic culture when treatment chosen on the basis of blood culture results fails. It is only the second reported case of hematogenous vertebral osteomyelitis caused by Bacteroides fragilis; previous cases of anaerobic vertebral osteomyelitis have been almost exclusively secondary to contiguous infection, notably decubitus ulcers.2
Case report A 68-year-old man presented with a 5-day history of fever, diaphoresis and intermittent chills. An empiric trial of erythromycin, 500 mg orally four times a day, was begun 2 days before presentation but had no effect. The patient denied bony pain or any other symptoms to suggest a focus of infection. His temperature was 38°C. Deep palpation revealed tenderness in the right upper qudrant. His prostate was normal; his stool was positive for occult blood. There were no further significant findings at that time. The patient's leukocyte count was 5.4 X 109/L (65% neutrophils, 21% lymphocytes, 14% band cells and 1+ toxic granulations), the blood hemoglobin level 138 g/L and the platelet count 67 X 109/L. The zeta sedimentation rate (ZSR) was 0.73 (normally 0.4 to 0.54). Urinalysis gave normal results; culture results of urine were also normal. Chest roentgenography, including a lateral view, showed no bony abnormalities. Cholelithiasis without biliary obstruction was found on ultrasound. The day after presentation intravenous therapy with ampicillin (1 g every 6 hours), metronidazole
(500 mg every 8 hours) and tobramycin (80 mg every 8 hours) was started. Blood samples taken on admission grew Proteus mirabilis in both aerobic and anaerobic bottles, which were subsequently discarded. Ogilvie's syndrome with colonic distention to the splenic flexure developed on the third day. No abscesses were seen on computed tomography (CT) of the abdomen. On the same day the patient complained of thoracic back pain. A bone scan and an indium- 111-labelled leukocyte scan showed increased uptake at the 10th and 1 1th thoracic vertebrae and in the intervening disc space. A presumptive diagnosis of vertebral osteomyelitis secondary to P. mirabilis was made; the patient received ampicillin, 6 g/d intravenously for 3 weeks, and then amoxicillin, 1500 mg/d orally for 3 weeks. The platelet count returned to normal, and the colonic distention resolved with conservative therapy. Seventeen days after admission colonoscopy demonstrated diverticulosis. The patient's fever subsided, and he remained asymptomatic until the sixth week of therapy, when his thoracic back pain recurred. He had tenderness with gibbus formation at the 10th thoracic vertebra. His leukocyte count was 8.2 x 109/L with a normal differential count. One week later the ZSR was 0.64. Plain x-ray films showed loss of the 10th thoracic disc space and vertebral compression at that level. In addition, there was sclerosis from the 7th to the 11th thoracic vertebrae. A CT scan revealed soft-tissue swelling anterior to the lower thoracic vertebrae. A sample obtained through fine-needle aspiration of the 10th thoracic disc space grew B. fragilis positive for j-lactamase in anaerobic culture. No other organisms were identified. Cultures were negative for tubercle bacilli, and cytologic examination showed no signs of malignant disease. After 3 weeks of intravenous therapy with cefa-
Dr. Feng is a resident in internal medicine, University of Western Ontario, London, Ont., and Dr. Austin is infectious diseases consultant, Victoria Hospital, London, Ont.
Reprint requests to: Dr. Thomas W. Austin, Infectious diseases consultant, Victoria Hospital, PO Box 5375, London, ON N6A 4G5 132
CAN MED ASSOC J 1991; 145 (2)
LE 1S JUILLET 1991
zolin, 1 g every 8 hours, and metronidazole, 500 mg every 8 hours, the regimen was changed to oral therapy with amoxicillin-potassium clavulanate, 500 and 125 mg respectively every 8 hours for 3 months. The patient remained afebrile, and there was no further progression of the vertebral compression.
Comments We suspect that our patient initially had polymicrobial bacteremia (likely of colonic origin) that went unnoticed because the blood cultures were discarded after isolation of P. mirabilis. His initial response to the ampicillin may have represented eradication of this more virulent organism, the subsequent deterioration representing the slower-acting B. fragilis infection. B. fragilis has been associated with osteomyelitis in various locations,2 but the first report of its association with hematogenous vertebral osteomyelitis was not until 1979.3 A MEDLINE search failed to produce cases reported since then. The implication of multiple organisms in hematogenous vertebral osteomyelitis is rare; infection of the urinary tract was the cause in one case.3 Our patient had no evidence of a urinary source of infection, and B. fragilis would be a rare urinary pathogen.4 This case demonstrates the importance of fineneedle aspiration of the intervertebral disc space if antimicrobial therapy based solely on blood culture results is inadequate. Failure of therapy should be suspected with recurrent back pain or radiographic evidence of progression. In addition, a decrease in the erythrocyte sedimentation rate to half or less than half of the pretherapy rate may indicate successful treatment.3 Fine-needle aspiration of the thoracic spine is a relatively safe procedure - a pneumothorax was the sole complication of 12 aspirations in a recent series.5 Anaerobic culture should be carried out routinely on all aspirates.
References 1. Sapico FL, Montgomerie JZ: Vertebral osteomyelitis. Dis Clin North Am 1990; 4: 539-550
Infect
2. Lewis RP, Sutter VL, Finegold SM: Bone infections involving anaerobic bacteria. Medicine 1978; 57: 279-298 3. Sapico FL, Montgomerie JZ: Pyogenic vertebral osteomyelitis: report of nine cases and review of the literature. Rev Infect Dis 1979; 1: 754-775 4. Siroky MB, Moylan RA, Austen G et al: Metastatic infection secondary to genitourinary tract sepsis. Am J Med 1976; 61:
35 1-360 5. El-Khoury GY, Terepka RH, Mickelson MR et al: Fine-needle aspiration biopsy of bone. J Bone Joint Surg [Am] 1983; 65: 522-525 JULY 15, 1991
Conferences continued from page 129 Oct. 2-4, 1991: Canadian Psychiatric Association 41 st Annual Meeting Saskatoon Inez Hoey, manager, Administrative Services, Canadian Psychiatric Association, 204-294 Albert St., Ottawa, ON KIP 6E6; (613) 234-2815, fax (613) 234-9857 Oct. 4, 1991: Clinical Hyperbaric and Diving Medicine (sponsored by the Hyperbaric Department, Toronto Hospital, and the Department of Anaesthesia, University of Toronto) Toronto General Division, Toronto Hospital Dr. G.H. Koch, CCRW G-821, 200 Elizabeth St., Toronto, ON M5G 2C4; (416) 340-4131, fax (416) 340-3698 Oct. 5, 1991: Canadian Council on Smoking and Health Annual Meeting Ottawa Andree Dumulon, national coordinator, Canadian Council on Smoking and Health, 400-1565 Carling Ave., Ottawa, ON K1Z 8R1; (613) 722-3419, fax (613) 725-9826 Du 9 au 11 oct. 1991 : Colloque international promouvoir la sante en francophonie - Au dela des cultures: des outils a partager (sous le parrainage du ministere de la Sante et des Services sociaux du Quebec) H6tel Bonaventure Hilton, Montreal Association pour la sante publique du Quebec, 3958, rue Dandurand, Montreal, QC HIX IP7; (514) 593-9939, fax (514) 725-2796
Oct. 23-26, 1991: American Medical Writers Association 51 st Annual Conference - World Class: Worldwide Biomedical Communications Royal York Hotel, Toronto American Medical Writers Association, 9650 Rockville Pike, Bethesda, MD 20814; (301) 493-0003 Nov. 1-2, 1991: Women, Food and Weight - New Perspectives 519 Church Street Community Centre, Toronto National Eating Disorder Information Centre, 200 Elizabeth St., Ste. CW1-328, Toronto, ON M5G 2C4; (416) 340-4156 Nov. 24-27, 1991: 4th Annual OPTIMA Conference Building Bridges to Well-being Radisson Hotel, Toronto Patti Etkin, conference coordinator, Donwood Institute, 175 Brentcliffe Rd., Toronto, ON M4G 3ZI; (416) 425-3930, fax (416) 425-7896 Dec. 11-15, 1991: American Back Society Fall Symposium on Back Pain San Francisco Marriott Hotel Dr. Aubrey A. Swartz, executive director, American Back Society, Ste. 401, 2647 E 14th St., Oakland, CA 94601; (415) 536-9929, fax (415) 536- 1812 CAN MED ASSOC J 1991; 145 (2)
133
