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Osteomyelitis * chance of therapeutic success. Parenteral antimicrobial agents "b are usually chosen initially; the efficacy of oral agents, espe- E cially those with high bioavailability, is increasingly reported. ii Rifampin should be used in combination with another antistaphylococcal agent to manage Staphglococcus aureus '.t- infections in the setting of orthopedic hardware if the hard- :: ... ware cannot be removed. Little evidence is available to guide recommendations on therapy duration; 4to 6 weeks of antibi- otics is considered sufficient for acute infections, whereas longer courses maybe required for chronic infections. In some circumstances, especially when hardware cannot be removed, indefinite suppressive therapy may be required. Relapse can occur many years after therapy completion.

* chance of therapeutic success. Parenteral antimicrobial agents "b are usually chosen initially; the efficacy of oral agents, espe- E cially those with high bioavailability, is increasingly reported. ii Rifampin should be used in combination with another antistaphylococcal agent to manage Staphglococcus aureus '.t- infections in the setting of orthopedic hardware if the hard- :: ... ware cannot be removed. Little evidence is available to guide recommendations on therapy duration; 4to 6 weeks of antibi- otics is considered sufficient for acute infections, whereas longer courses maybe required for chronic infections. In some circumstances, especially when hardware cannot be removed, indefinite suppressive therapy may be required. Relapse can occur many years after therapy completion. rEY POtflTS . Unless systemic signs of sepsis or concomitant soft tis- sue infection or bacteremia are present, empiric antibi- otics should be withheld in suspected osteomyelitis until a bone biopsy is obtained. o Surgical debridement is indicated for osteomyelitis if bone necrosis is extensive. FIGURE 2 6. The MRI scan shows gadolinium enhancement on theTl-weighted o Four to six weeks of antibiotic therapy is usually suffi- images at the inferior endplate of L4 and the superior endplate of L5 with loss of endplate definition. cient for acute osteomyelitis; longer courses are required for chronic infections.

rEY POtflTS . Unless systemic signs of sepsis or concomitant soft tis- sue infection or bacteremia are present, empiric antibi- otics should be withheld in suspected osteomyelitis until a bone biopsy is obtained. o Surgical debridement is indicated for osteomyelitis if bone necrosis is extensive. FIGURE 2 6. The MRI scan shows gadolinium enhancement on theTl-weighted o Four to six weeks of antibiotic therapy is usually suffi- images at the inferior endplate of L4 and the superior endplate of L5 with loss of endplate definition. cient for acute osteomyelitis; longer courses are required for chronic infections. Bone Biopsy Obtaining biopsy material for culture and pathologic exami- Evaluation and Management nation is essential to evaluating suspected osteomyelitis. of Osteomyelitis in Diabetic Confirming the presence of a pathogen maximizes the chance that the chosen antibiotic therapy will be successful. Foot Ulcers Specimens may be obtained at surgery or by image-guided Diabetic foot infections are the most frequent diabetes-related biopsy. A bone biopsy is generally not required in persons with complication necessitating hospitalization, cause significant positive blood culture results. Persons who inject drugs are a morbidity (limb amputation), and are associated with increased possible exception because the organism in the blood culture mortality. Nonhealing ulcers are a source of infection and may may not represent the pathogen in the bone. In culture- spread contiguously to bone. negative disease, additional testing of biopsy material with Osteomyelitis should be considered when a diabetic foot nucleic acid amplification techniques may yield the causative ulcer is deep (presence of exposed bone), Iarge (>2 cm in organism, although these techniques will not provide infor- diameter), or chronic (nonhealing after 6 weeks of standard mation regarding antimicrobial susceptibilities. care). Up to two thirds of affected patients do not have leuko- cytosis or elevated inflammatory markers. A probe-to-bone I(EY POITI test (sterile probe inserted into the ulcer base to evaluate pen- o Obtaining biopsy material for culture and pathologic etration to bone or joint capsule) should be performed. In a examination is essential to the evaluation and treatment clinically infected ulcer (pus present), the positive predictive of suspected osteomyelitis. value of the probe-to-bone test is high; in a noninfected ulcer, the negative predictive value is high. Imaging options are as described for other causes of osteomyelitis. All patients with a Treatment new diabetic foot infection should have plain radiography to Susceptibility testing from bone or blood culture isolates and assess for bony abnormalities, soft tissue gas, and foreign knowledge of antibiotic levels achievable in bone for the bodies. selected agent should guide antibiotic therapy for osteomyeli- Bone samples for histologic confirmation of diagnosis and tis. Unless systemic signs of sepsis or concomitant soft tissue for culture can be obtained during bone debridement or bone infection or bacteremia are present, empiric antibiotics should biopsy. The correlation with deep wound cultures and bone be withheld until a bone biopsy is obtained. Surgical debride- biopsy samples is variable, and bone biopsy remains the rec- ment is indicated if bone necrosis is extensive. Orthopedic ommended modality for microbiologic diagnosis. S. cureus hardware should be removed, if possible, to increase the and streptococcal species account for most osteomyelitis

Bone Biopsy Obtaining biopsy material for culture and pathologic exami- Evaluation and Management nation is essential to evaluating suspected osteomyelitis. of Osteomyelitis in Diabetic Confirming the presence of a pathogen maximizes the chance that the chosen antibiotic therapy will be successful. Foot Ulcers Specimens may be obtained at surgery or by image-guided Diabetic foot infections are the most frequent diabetes-related biopsy. A bone biopsy is generally not required in persons with complication necessitating hospitalization, cause significant positive blood culture results. Persons who inject drugs are a morbidity (limb amputation), and are associated with increased possible exception because the organism in the blood culture mortality. Nonhealing ulcers are a source of infection and may may not represent the pathogen in the bone. In culture- spread contiguously to bone. negative disease, additional testing of biopsy material with Osteomyelitis should be considered when a diabetic foot nucleic acid amplification techniques may yield the causative ulcer is deep (presence of exposed bone), Iarge (>2 cm in organism, although these techniques will not provide infor- diameter), or chronic (nonhealing after 6 weeks of standard mation regarding antimicrobial susceptibilities. care). Up to two thirds of affected patients do not have leuko- cytosis or elevated inflammatory markers. A probe-to-bone I(EY POITI test (sterile probe inserted into the ulcer base to evaluate pen- o Obtaining biopsy material for culture and pathologic etration to bone or joint capsule) should be performed. In a examination is essential to the evaluation and treatment clinically infected ulcer (pus present), the positive predictive of suspected osteomyelitis. value of the probe-to-bone test is high; in a noninfected ulcer, the negative predictive value is high. Imaging options are as described for other causes of osteomyelitis. All patients with a Treatment new diabetic foot infection should have plain radiography to Susceptibility testing from bone or blood culture isolates and assess for bony abnormalities, soft tissue gas, and foreign knowledge of antibiotic levels achievable in bone for the bodies. selected agent should guide antibiotic therapy for osteomyeli- Bone samples for histologic confirmation of diagnosis and tis. Unless systemic signs of sepsis or concomitant soft tissue for culture can be obtained during bone debridement or bone infection or bacteremia are present, empiric antibiotics should biopsy. The correlation with deep wound cultures and bone be withheld until a bone biopsy is obtained. Surgical debride- biopsy samples is variable, and bone biopsy remains the rec- ment is indicated if bone necrosis is extensive. Orthopedic ommended modality for microbiologic diagnosis. S. cureus hardware should be removed, if possible, to increase the and streptococcal species account for most osteomyelitis 52

Osteomyelitis complicating diabetic foot ulcers; gram-negative organisms when accompanied by elevated inflammatory marker levels, are found in as many as 25% of infections. Anaerobes are much neurologic findings, or unexplained fever. Neurologic findings less common. Infections may be polymicrobial. can include sensory loss, weakness, or radiculopathy and are If infected but viable bone is present, a 4- to 6-week reported in up to one third of patients. Point tenderness is course of parenteral or oral antibiotic therapy is recom- present in only one third of patients. mended. Prolonged oral therapy is indicated if residual MRI is the preferred imaging modality. Blood cultures necrotic bone is present. should be performed in all patients before antibiotics are Indications for amputation include persistent sepsis, started. Testing for My cobacterium tuberculosis infection, inability to tolerate antibiotic therapy, progressive bone fungal blood cultures, and serologic tests for Brucello species destruction despite appropriate therapy, or bone destruction are appropriate for patients at risk for these pathogens (see that compromises the mechanical integrity of the foot. The My cobacterium tuberculosis Infection, Fungal Infections, patient may also choose amputation over prolonged antibi- and Travel Medicine). A positive Brucella serologic result in otic therapy. However, limb salvage may be possible when the correct epidemiologic setting is considered diagnostic, treatment is directed by a multidisciplinary team consisting and biopsy is unnecessary. Otherwise, image-guided biopsy of a foot surgeon, a vascular surgeon, an internist, an infec- has a diagnostic yield of approximately 60% and should be tious diseases specialist, nurses, and a physical therapist. used in patients with negative blood culture results. A sec- Hyperbaric oxygen therapy, growth factors, and topical neg- ond biopsy should be obtained if the first is not diagnostic. ative pressure therapy have insufficient evidence of benefit Nucleic acid amplification techniques can increase biopsy to recommend their use. yield; specimens should also be sent for pathologic examina- tion. Open biopsy or percutaneous endoscopic diskectomy r(EY P0t1{TS and drainage may be considered if the microbiologic diagno- o Osteomyelitis should be considered when a diabetic sis remains elusive after a second image-guided biopsy foot ulcer is deep (presence of exposed bone), Iarge attempt. (>z cm in diameter), or chronic (nonhealing after 6 weeks Patients with neurologic compromise or evidence of spi- ofstandard care). nal instability should undergo evaluation for immediate surgi . Bone samples for diagnosis and guidance of antimicro- cal intervention. Patients with severe sepsis, progressive bial therapy should be obtained in patients with osteo- neurologic deficit, spinal instability, or epidural abscess should myelitis during bone debridement or by bone biopsy. receive empiric antibiotic therapy. Otherwise, initiation of o If infected but viable bone is present in patients with antibiotic therapy for uncomplicated vertebral osteomyelitis is diabetes mellitus-associated osteomyelitis, a 4- to based on culture results. Parenteral therapy is generally rec 6-week course of antibiotic therapy is recommended; ommended, especially for S. oureus. However, oral agents with prolonged oral therapy is indicated for patients with high bioavailability and good bone penetration (such as fluo- residual necrotic bone. roquinolones) may be used, especially for Enterobacteriaceae. Antibiotic therapy duration is typically 6 weeks. Infections caused by MRSA, those associated with undrained paraverte- bral or psoas abscess, and those in persons with end stage Evaluation and Management of kidney disease may require more prolonged therapy. Repeat Vertebra I Osteomyelitis imaging, especially MRI, should be reserved for patients who Vertebral osteomyelitis is almost exclusively secondary to do not respond clinically. hematogenous dissemination. Risk factors include older age, r(EY POtl{TS immunocompromise, indwelling catheters, hemodialysis, and injection drug use. Infection occurs in the intervertebral . New-onset back or neck pain or progressive worsening disk space and then spreads to the adjacent vertebral bodies of chronic pain that is unresponsive to conservative (spondylodiskitis). The lumbar spine is most frequently management should raise concern for vertebral osteo- involved, followed by the thoracic and then the cervical myelitis, especially when accompanied by elevated spine. Positive blood cultures may obviate the need for bone inflammatory markers, neurologic findings, or unex- plained fever. biopsy. Most infections are caused by S. oureus, but persis- tent bacteremia with coagulase-negative staphylococci may o The diagnostic evaluation of vertebral osteomyelitis also be the result of osteomyelitis. Enterobacteriaceae, should include blood cultures for all patients. Pseudomonas aeruginosa (especially in persons who inject . Parenteral antibiotic therapy chosen based on culture drugs), and Candida species may also cause vertebral results is recommended for uncomplicated vertebral osteomyelitis. osteomyelitis, although oral agents with high bioavaila- New-onset back or neck pain or progressive worsening of bility and good bone penetration can be used; treatment chronic pain that is unresponsive to conservative management duration is typicallY 6 weeks. should raise concern for vertebral osteomyelitis, especially

complicating diabetic foot ulcers; gram-negative organisms when accompanied by elevated inflammatory marker levels, are found in as many as 25% of infections. Anaerobes are much neurologic findings, or unexplained fever. Neurologic findings less common. Infections may be polymicrobial. can include sensory loss, weakness, or radiculopathy and are If infected but viable bone is present, a 4- to 6-week reported in up to one third of patients. Point tenderness is course of parenteral or oral antibiotic therapy is recom- present in only one third of patients. mended. Prolonged oral therapy is indicated if residual MRI is the preferred imaging modality. Blood cultures necrotic bone is present. should be performed in all patients before antibiotics are Indications for amputation include persistent sepsis, started. Testing for My cobacterium tuberculosis infection, inability to tolerate antibiotic therapy, progressive bone fungal blood cultures, and serologic tests for Brucello species destruction despite appropriate therapy, or bone destruction are appropriate for patients at risk for these pathogens (see that compromises the mechanical integrity of the foot. The My cobacterium tuberculosis Infection, Fungal Infections, patient may also choose amputation over prolonged antibi- and Travel Medicine). A positive Brucella serologic result in otic therapy. However, limb salvage may be possible when the correct epidemiologic setting is considered diagnostic, treatment is directed by a multidisciplinary team consisting and biopsy is unnecessary. Otherwise, image-guided biopsy of a foot surgeon, a vascular surgeon, an internist, an infec- has a diagnostic yield of approximately 60% and should be tious diseases specialist, nurses, and a physical therapist. used in patients with negative blood culture results. A sec- Hyperbaric oxygen therapy, growth factors, and topical neg- ond biopsy should be obtained if the first is not diagnostic. ative pressure therapy have insufficient evidence of benefit Nucleic acid amplification techniques can increase biopsy to recommend their use. yield; specimens should also be sent for pathologic examina- tion. Open biopsy or percutaneous endoscopic diskectomy r(EY P0t1{TS and drainage may be considered if the microbiologic diagno- o Osteomyelitis should be considered when a diabetic sis remains elusive after a second image-guided biopsy foot ulcer is deep (presence of exposed bone), Iarge attempt. (>z cm in diameter), or chronic (nonhealing after 6 weeks Patients with neurologic compromise or evidence of spi- ofstandard care). nal instability should undergo evaluation for immediate surgi . Bone samples for diagnosis and guidance of antimicro- cal intervention. Patients with severe sepsis, progressive bial therapy should be obtained in patients with osteo- neurologic deficit, spinal instability, or epidural abscess should myelitis during bone debridement or by bone biopsy. receive empiric antibiotic therapy. Otherwise, initiation of o If infected but viable bone is present in patients with antibiotic therapy for uncomplicated vertebral osteomyelitis is diabetes mellitus-associated osteomyelitis, a 4- to based on culture results. Parenteral therapy is generally rec 6-week course of antibiotic therapy is recommended; ommended, especially for S. oureus. However, oral agents with prolonged oral therapy is indicated for patients with high bioavailability and good bone penetration (such as fluo- residual necrotic bone. roquinolones) may be used, especially for Enterobacteriaceae. Antibiotic therapy duration is typically 6 weeks. Infections caused by MRSA, those associated with undrained paraverte- bral or psoas abscess, and those in persons with end stage Evaluation and Management of kidney disease may require more prolonged therapy. Repeat Vertebra I Osteomyelitis imaging, especially MRI, should be reserved for patients who Vertebral osteomyelitis is almost exclusively secondary to do not respond clinically. hematogenous dissemination. Risk factors include older age, r(EY POtl{TS immunocompromise, indwelling catheters, hemodialysis, and injection drug use. Infection occurs in the intervertebral . New-onset back or neck pain or progressive worsening disk space and then spreads to the adjacent vertebral bodies of chronic pain that is unresponsive to conservative (spondylodiskitis). The lumbar spine is most frequently management should raise concern for vertebral osteo- involved, followed by the thoracic and then the cervical myelitis, especially when accompanied by elevated spine. Positive blood cultures may obviate the need for bone inflammatory markers, neurologic findings, or unex- plained fever. biopsy. Most infections are caused by S. oureus, but persis- tent bacteremia with coagulase-negative staphylococci may o The diagnostic evaluation of vertebral osteomyelitis also be the result of osteomyelitis. Enterobacteriaceae, should include blood cultures for all patients. Pseudomonas aeruginosa (especially in persons who inject . Parenteral antibiotic therapy chosen based on culture drugs), and Candida species may also cause vertebral results is recommended for uncomplicated vertebral osteomyelitis. osteomyelitis, although oral agents with high bioavaila- New-onset back or neck pain or progressive worsening of bility and good bone penetration can be used; treatment chronic pain that is unresponsive to conservative management duration is typicallY 6 weeks. should raise concern for vertebral osteomyelitis, especially 53