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Pathological Fracture of the Right Distal Radius Caused by Enterobacter aerogenes Osteomyelitis in an Adult
CASE REPORT
Pathological Fracture of the Right Distal Radius Caused by Enterobacter aerogenes Osteomyelitis in an Adult Te-Yu Lin, MD, Hung-Wei Chi, MD and Ning-Chi Wang, MD
Abstract: A pathological fracture is a break in a diseased bone caused by weakening of the bone structure by a pathological process with no identifiable trauma. Acute bacterial osteomyelitis that results in pathological fractures in the extremities is rare in adults. To our knowledge, we report the first case of Enterobacter aerogenes osteomyelitis of the right distal radius, complicated with a pathological fracture, in a 79-year-old man with diabetes, which was diagnosed by radiological, microbiological, and histopathological examinations. He recovered well after an 8-week course of antibiotics and surgical debridement. This highlights the fact that radial osteomyelitis should be included in the differential diagnosis when an elderly diabetic patient with no history of trauma presents with pain in the forearm. Key Indexing Terms: Pathological fracture; Enterobacter aerogenes; Osteomyelitis. [Am J Med Sci 2010;339(5):493–494.]
A
pathological fracture is a break in a diseased bone caused by weakening of the bone structure by a pathological process (eg, primary or metastatic tumor, infection, osteomalacia, osteoporosis, osteogenesis imperfecta, fibrous dysplasia, bone cyst, and Paget’s disease) with no identifiable trauma.1 Acute bacterial osteomyelitis that results in pathological fractures in the extremities is rare in adults. We present, to our knowledge, the first reported case of a pathological fracture of the distal radius caused by Enterobacter aerogenes osteomyelitis in a 79-year-old man with diabetes, who was successfully treated with antibiotics and surgical intervention.
CASE REPORT A 79-year-old man presented with a 2-week history of painful sensations in the right forearm. There was no history of trauma before the symptom occurred. He had a history of hypertension and type 2 diabetes; in addition, he had been eating sashimi for 10 years. During the preceding 2 weeks, he experienced pain in the right forearm, requiring increasing analgesia. He visited the emergency department at our hospital and was admitted. He denied any antibiotic exposure before admission. On admission, his blood pressure was 108/70 mm Hg; pulse rate, 75 beats/min; respiratory rate, 18/min; and body temperature, 36.6°C. Physical examination revealed tenderness over the distal portion of the right forearm. Laboratory studies revealed the following values: hemoglobin, 8.3 g/dL; white blood cell count, 15.5 cells/mm3; platelets, 274 cells/mm3; erythrocyte sedimentation rate, 100 mm/h; and C-reactive protein, 9.6 mg/dL. Radiography of the right forearm revealed a complete fracture of the distal radius
Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan. Submitted January 10, 2010; accepted in revised form February 16, 2010. Correspondence: Te-Yu Lin, Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, No. 325, Section 2, Cheng-Kung Road, Neihu 114, Taipei, Taiwan, Republic of China (E-mail: [email protected]).
associated with osteoporotic change and an irregular periosteal reaction (Figure 1). Cast immobilization was then performed. A pathological fracture was suspected, and magnetic resonance imaging of the right upper forearm was done, which revealed a long-segment osteolytic lesion and a lobulated soft tissue infiltration mass, with cortical destruction over the right radial bone (Figure 2). A bone biopsy was conducted, and a purulent discharge with necrotic tissue was noted. A histopathological examination of the biopsy specimen revealed granulation tissue but no evidence of malignancy. E aerogenes was found in the bacterial culture, which was susceptible to piperacillin-tazobactam, ceftazidime, ciprofloxacin, imipenem, and ertapenem. Thus, E aerogenes osteomyelitis of the right distal radius was diagnosed, based on these radiological, microbiological, and histopathological findings. The patient received intravenous ertapenem (1 g daily) for 2 weeks and oral ciprofloxacin (750 mg twice daily) for 6 weeks. Two months subsequent to the completion of antibiotic therapy, the patient’s erythrocyte sedimentation rate had returned to normal, and the patient recovered fully.
DISCUSSION The genus Enterobacter has 14 species, and E aerogenes and Enterobacter cloacae are by far the most frequently encountered human pathogens.2 Enterobacter species have been implicated in a broad range of clinical syndromes, such as bacteremia; skin and soft tissue infections; and respiratory tract, urinary tract, bone and joints, central nervous system, and gastrointestinal tract infections. Among these clinical syndromes, osteomyelitis is rarely encountered. There are a few case reports of osteomyelitis caused by Enterobacter species over the past 3 decades.3– 6 The most common pathogen was E cloacae. In this case, magnetic resonance imaging of the right upper forearm showed cortical destruction over the right radial bone, and E aerogenes grew in the bone biopsy culture. To our knowledge, this is the first reported case of E aerogenes osteomyelitis. Osteomyelitis is an acute or chronic inflammatory process of the bone from infection with pyogenic organisms. In children, acute osteomyelitis most commonly occurs in the distal femur and proximal tibia. However, in adults, the most common sites are the vertebrae, sternoclavicular joint, sacroiliac joint, and symphysis pubis.7 In addition, acute bacterial osteomyelitis complicated with a pathological fracture of a long bone is rare in adults. Most cases reported in the medical literature have occurred in children, including those with an underlying sickle cell disease.8 Our case was of an adult, and the location is different from that of previous reports. Osteomyelitis can occur because of contiguous spread from adjacent soft tissues and joints, hematogenous seeding, or direct inoculation of the microorganism into the bone as a result of trauma or surgery. Our case had no history of trauma or adjacent soft tissue or joints infection. Thus, we suggest that its etiology involved hematogenous seeding. Enterobacter species
The American Journal of the Medical Sciences • Volume 339, Number 5, May 2010
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Lin et al
FIGURE 1. Radiography of the right forearm shows a complete fracture of the right distal radius, with osteoporotic change and irregular periosteum reaction.
can be found in the feces of humans and animals and in water, plants and plant materials, insects, and dairy products.9 In this case, the scenario for osteomyelitis caused by E aerogenes is summarized as follows. The patient ate sashimi often, and therefore E aerogenes could have colonized in the gastrointestinal tract. Furthermore, diabetic patients might have some mucosal defect, providing a portal of entry for bacteremia and seeding to the radius, thus resulting in acute osteomyelitis.10
Early diagnosis, adequate drainage of the purulent material, and use of appropriate antibiotics therapy are the cornerstones of successful treatment.11 The usual microbial cause of osteomyelitis is Staphylococcus aureus and coagulase-negative Staphylococci; they account for 60% to 70% of cases, and Enterobacter species are occasionally encountered.12 Initial antibiotic therapy for osteomyelitis should include a broadspectrum agent with good S aureus coverage with subsequent modification, based on culture and sensitivity results. In the case of osteomyelitis, treatment with an intravenous agent followed by an oral agent, when clinical improvement has occurred, for a total of 42 to 56 days seems to be appropriate. The fact that the microbial cause of osteomyelitis in this case was a Gram-negative bacillus, rather than the usual Grampositive cocci, should remind physicians that the empirical coverage of Gram-negative organisms should also be considered in diabetic patients. Pathological fracture is a rare complication of acute bacterial osteomyelitis in adults. This case shows us that radial osteomyelitis should be considered in the differential diagnosis when an elderly diabetic patient with no history of trauma presents with the pain in the forearm. Radiological examinations must be performed, and if osteomyelitis is highly suspected, a microbiological culture of the surgical specimen must be obtained to determine the pathogen. Both adequate antibiotics and surgical intervention are important for the successful treatment of pathological fractures caused by acute bacterial osteomyelitis. REFERENCES 1. Siber HR. Pathological fractures. In: Connolly JF, editor. Depalma’s the management of fractures and dislocations. 3rd ed. Philadelphia (PA): W.B. Saunders; 1993. p. 2088 –90. 2. Chow JW, Yu VL, Shlaes DM. Epidemiologic perspectives on Enterobacter for the infection control professional. Am J Infect Control 1994;22:195–201. 3. John JF, Sharbaugh RJ, Bannister ER. Enterobacter cloacae: bacteremia, epidemiology, and antibiotic resistance. Rev Infect Dis 1982; 4:13–28. 4. Marce S, Antoine JF, Schaeverbeke T, et al. Enterobacter cloacae vertebral infection in a heroin addict with HIV infection. Ann Rheum Dis 1993;52:695. 5. Solans R, Simeon P, Cuenca R, et al. Infectious discitis caused by Enterobacter cloacae. Ann Rheum Dis 1992;51:906 –7. 6. Westbloom TU, Coggins ME. Osteomyelitis caused by Enterobacter taylorae, formerly enteric group 19. J Clin Microbiol 1987;25:2432–3. 7. Waldvogel FA. Osteomyelitis. In: Gorbach SL, editor. Infectious diseases. 2nd ed. Philadelphia (PA): W.B. Saunders; 1998. p. 1339 – 44. 8. Ebong WW. Pathological fracture complicating long bone osteomyelitis in patients with sickle cell disease. J Pediatr Orthop 1986;6:177– 81. 9. Sanders WE Jr, Sanders CC. Enterobacter spp.: pathogens poised to flourish at the turn of the century. Clin Microbiol Rev 1997;4:220 – 41. 10. De Las Casas LE, Finley JL. Diabetic microangiopathy in the small bowel. Histopathology 1999;35:267–70. 11. Lew DP, Waldvogel FA. Osteomyelitis. Lancet 2004;364:369 –79.
FIGURE 2. Magnetic resonance imaging shows a long-segment osteolytic lesion and a lobulated soft tissue infiltration mass with cortex destruction, encasing the right radial bone.
494
12. Berbari EF, Steckelberg JM, Osmon DR. Osteomyelitis. In: Mandell GL, Bennett JE, Dolin R. editors. Mandell, Douglas, and Bennett’s principles and practice of infectious disease. 6th ed. Philadelphia (PA): Churchill Livingstone; 2005. p. 1322–32.
Volume 339, Number 5, May 2010
Pathological Fracture of the Right Distal Radius Caused by Enterobacter aerogenes Osteomyelitis in an Adult Te-Yu Lin, MD, Hung-Wei Chi, MD and Ning-Chi Wang, MD
Abstract: A pathological fracture is a break in a diseased bone caused by weakening of the bone structure by a pathological process with no identifiable trauma. Acute bacterial osteomyelitis that results in pathological fractures in the extremities is rare in adults. To our knowledge, we report the first case of Enterobacter aerogenes osteomyelitis of the right distal radius, complicated with a pathological fracture, in a 79-year-old man with diabetes, which was diagnosed by radiological, microbiological, and histopathological examinations. He recovered well after an 8-week course of antibiotics and surgical debridement. This highlights the fact that radial osteomyelitis should be included in the differential diagnosis when an elderly diabetic patient with no history of trauma presents with pain in the forearm. Key Indexing Terms: Pathological fracture; Enterobacter aerogenes; Osteomyelitis. [Am J Med Sci 2010;339(5):493–494.]
A
pathological fracture is a break in a diseased bone caused by weakening of the bone structure by a pathological process (eg, primary or metastatic tumor, infection, osteomalacia, osteoporosis, osteogenesis imperfecta, fibrous dysplasia, bone cyst, and Paget’s disease) with no identifiable trauma.1 Acute bacterial osteomyelitis that results in pathological fractures in the extremities is rare in adults. We present, to our knowledge, the first reported case of a pathological fracture of the distal radius caused by Enterobacter aerogenes osteomyelitis in a 79-year-old man with diabetes, who was successfully treated with antibiotics and surgical intervention.
CASE REPORT A 79-year-old man presented with a 2-week history of painful sensations in the right forearm. There was no history of trauma before the symptom occurred. He had a history of hypertension and type 2 diabetes; in addition, he had been eating sashimi for 10 years. During the preceding 2 weeks, he experienced pain in the right forearm, requiring increasing analgesia. He visited the emergency department at our hospital and was admitted. He denied any antibiotic exposure before admission. On admission, his blood pressure was 108/70 mm Hg; pulse rate, 75 beats/min; respiratory rate, 18/min; and body temperature, 36.6°C. Physical examination revealed tenderness over the distal portion of the right forearm. Laboratory studies revealed the following values: hemoglobin, 8.3 g/dL; white blood cell count, 15.5 cells/mm3; platelets, 274 cells/mm3; erythrocyte sedimentation rate, 100 mm/h; and C-reactive protein, 9.6 mg/dL. Radiography of the right forearm revealed a complete fracture of the distal radius
Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan. Submitted January 10, 2010; accepted in revised form February 16, 2010. Correspondence: Te-Yu Lin, Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, No. 325, Section 2, Cheng-Kung Road, Neihu 114, Taipei, Taiwan, Republic of China (E-mail: [email protected]).
associated with osteoporotic change and an irregular periosteal reaction (Figure 1). Cast immobilization was then performed. A pathological fracture was suspected, and magnetic resonance imaging of the right upper forearm was done, which revealed a long-segment osteolytic lesion and a lobulated soft tissue infiltration mass, with cortical destruction over the right radial bone (Figure 2). A bone biopsy was conducted, and a purulent discharge with necrotic tissue was noted. A histopathological examination of the biopsy specimen revealed granulation tissue but no evidence of malignancy. E aerogenes was found in the bacterial culture, which was susceptible to piperacillin-tazobactam, ceftazidime, ciprofloxacin, imipenem, and ertapenem. Thus, E aerogenes osteomyelitis of the right distal radius was diagnosed, based on these radiological, microbiological, and histopathological findings. The patient received intravenous ertapenem (1 g daily) for 2 weeks and oral ciprofloxacin (750 mg twice daily) for 6 weeks. Two months subsequent to the completion of antibiotic therapy, the patient’s erythrocyte sedimentation rate had returned to normal, and the patient recovered fully.
DISCUSSION The genus Enterobacter has 14 species, and E aerogenes and Enterobacter cloacae are by far the most frequently encountered human pathogens.2 Enterobacter species have been implicated in a broad range of clinical syndromes, such as bacteremia; skin and soft tissue infections; and respiratory tract, urinary tract, bone and joints, central nervous system, and gastrointestinal tract infections. Among these clinical syndromes, osteomyelitis is rarely encountered. There are a few case reports of osteomyelitis caused by Enterobacter species over the past 3 decades.3– 6 The most common pathogen was E cloacae. In this case, magnetic resonance imaging of the right upper forearm showed cortical destruction over the right radial bone, and E aerogenes grew in the bone biopsy culture. To our knowledge, this is the first reported case of E aerogenes osteomyelitis. Osteomyelitis is an acute or chronic inflammatory process of the bone from infection with pyogenic organisms. In children, acute osteomyelitis most commonly occurs in the distal femur and proximal tibia. However, in adults, the most common sites are the vertebrae, sternoclavicular joint, sacroiliac joint, and symphysis pubis.7 In addition, acute bacterial osteomyelitis complicated with a pathological fracture of a long bone is rare in adults. Most cases reported in the medical literature have occurred in children, including those with an underlying sickle cell disease.8 Our case was of an adult, and the location is different from that of previous reports. Osteomyelitis can occur because of contiguous spread from adjacent soft tissues and joints, hematogenous seeding, or direct inoculation of the microorganism into the bone as a result of trauma or surgery. Our case had no history of trauma or adjacent soft tissue or joints infection. Thus, we suggest that its etiology involved hematogenous seeding. Enterobacter species
The American Journal of the Medical Sciences • Volume 339, Number 5, May 2010
493
Lin et al
FIGURE 1. Radiography of the right forearm shows a complete fracture of the right distal radius, with osteoporotic change and irregular periosteum reaction.
can be found in the feces of humans and animals and in water, plants and plant materials, insects, and dairy products.9 In this case, the scenario for osteomyelitis caused by E aerogenes is summarized as follows. The patient ate sashimi often, and therefore E aerogenes could have colonized in the gastrointestinal tract. Furthermore, diabetic patients might have some mucosal defect, providing a portal of entry for bacteremia and seeding to the radius, thus resulting in acute osteomyelitis.10
Early diagnosis, adequate drainage of the purulent material, and use of appropriate antibiotics therapy are the cornerstones of successful treatment.11 The usual microbial cause of osteomyelitis is Staphylococcus aureus and coagulase-negative Staphylococci; they account for 60% to 70% of cases, and Enterobacter species are occasionally encountered.12 Initial antibiotic therapy for osteomyelitis should include a broadspectrum agent with good S aureus coverage with subsequent modification, based on culture and sensitivity results. In the case of osteomyelitis, treatment with an intravenous agent followed by an oral agent, when clinical improvement has occurred, for a total of 42 to 56 days seems to be appropriate. The fact that the microbial cause of osteomyelitis in this case was a Gram-negative bacillus, rather than the usual Grampositive cocci, should remind physicians that the empirical coverage of Gram-negative organisms should also be considered in diabetic patients. Pathological fracture is a rare complication of acute bacterial osteomyelitis in adults. This case shows us that radial osteomyelitis should be considered in the differential diagnosis when an elderly diabetic patient with no history of trauma presents with the pain in the forearm. Radiological examinations must be performed, and if osteomyelitis is highly suspected, a microbiological culture of the surgical specimen must be obtained to determine the pathogen. Both adequate antibiotics and surgical intervention are important for the successful treatment of pathological fractures caused by acute bacterial osteomyelitis. REFERENCES 1. Siber HR. Pathological fractures. In: Connolly JF, editor. Depalma’s the management of fractures and dislocations. 3rd ed. Philadelphia (PA): W.B. Saunders; 1993. p. 2088 –90. 2. Chow JW, Yu VL, Shlaes DM. Epidemiologic perspectives on Enterobacter for the infection control professional. Am J Infect Control 1994;22:195–201. 3. John JF, Sharbaugh RJ, Bannister ER. Enterobacter cloacae: bacteremia, epidemiology, and antibiotic resistance. Rev Infect Dis 1982; 4:13–28. 4. Marce S, Antoine JF, Schaeverbeke T, et al. Enterobacter cloacae vertebral infection in a heroin addict with HIV infection. Ann Rheum Dis 1993;52:695. 5. Solans R, Simeon P, Cuenca R, et al. Infectious discitis caused by Enterobacter cloacae. Ann Rheum Dis 1992;51:906 –7. 6. Westbloom TU, Coggins ME. Osteomyelitis caused by Enterobacter taylorae, formerly enteric group 19. J Clin Microbiol 1987;25:2432–3. 7. Waldvogel FA. Osteomyelitis. In: Gorbach SL, editor. Infectious diseases. 2nd ed. Philadelphia (PA): W.B. Saunders; 1998. p. 1339 – 44. 8. Ebong WW. Pathological fracture complicating long bone osteomyelitis in patients with sickle cell disease. J Pediatr Orthop 1986;6:177– 81. 9. Sanders WE Jr, Sanders CC. Enterobacter spp.: pathogens poised to flourish at the turn of the century. Clin Microbiol Rev 1997;4:220 – 41. 10. De Las Casas LE, Finley JL. Diabetic microangiopathy in the small bowel. Histopathology 1999;35:267–70. 11. Lew DP, Waldvogel FA. Osteomyelitis. Lancet 2004;364:369 –79.
FIGURE 2. Magnetic resonance imaging shows a long-segment osteolytic lesion and a lobulated soft tissue infiltration mass with cortex destruction, encasing the right radial bone.
494
12. Berbari EF, Steckelberg JM, Osmon DR. Osteomyelitis. In: Mandell GL, Bennett JE, Dolin R. editors. Mandell, Douglas, and Bennett’s principles and practice of infectious disease. 6th ed. Philadelphia (PA): Churchill Livingstone; 2005. p. 1322–32.
Volume 339, Number 5, May 2010