A Brief Synopsis of AFP's "Diagnosis and Management of Osteomyelitis"

A synopsis of: Diagnosis and Management of Osteomyelitis
JOHN HATZENBUEHLER, MD, and THOMAS J. PULLING, MD, Maine Medical Center, Portland, Maine
 http://www.aafp.org/afp/2011/1101/p1027.pdf
Am Fam Physician. 2011 Nov 1;84(9):1027-1033.

     I was gonna read a different article today, but in the spirit of twitter, I am going to read the article the AFP just tweeted the link to...
     Osteomyelitis can be separated into acute or chronic, and also by mechanism of infection. Acute osteomyelitis presents within the first two weeks after an infection. Inflammatory changes are seen. In chronic osteomyelitis, necrotic bone is seen after 6 weeks. The infection can come from an open wound, exposed bone, or hematogenous spread. The most common bug is Staphylococcus aureus, followed by Group A strep, Streptococcus pneumoniae, and Kingella kingae. Groups B strep is seen mostly in newborns. Some other notable bugs are S. epidermidis,  P. aeruginosa, S. marcescens, E. coli,  as well as fungi and mycobacteria.
     Acute hematogenous osteomyelitis is most common in children (5 years old and younger) due to bacterial seeding of the highly vascular metaphyseal bone. Patients will present with systemic symptoms such as fever irritability, swelling, erythema, or tenderness over the infected bone. It will occur about two weeks after onset.  These patients usually require a shorter course of antibiotics (4 days IV, then 4 weeks PO). Immunocompromised patients may need up to 6 weeks of treatment.
     Chronic osteomyelitis will be seen with exposed bone, open fractures, bacteremia, and soft tissue infections. These are common in patients who are bedridden, in diabetic neuropathy, peripheral vascular disease, or condition with slow wound healing. This takes about three months to be an issue. It is rare for a prosthetic joint to be infected. The recurrence rate of chronic osteomyelitis is about 30%  a year. Those infected with P. aeruginosa have an even high recurrence rate. Parenteral antibiotics are recommended for 4-6 weeks in patients with chronic osteomyelitis. They will then be transitioned to oral medications for another two weeks.
     Hematogenous osteomyelitis is seen with patients who have an underlying disease, such as diabetes, chronic renal disease, IVDA or cancer. It is more common in adults. It affects the vertebrae, long bones, pelvis, and clavicle.
    Symptoms of osteomyelitis include fever, irritability, and lethargy. On physical exam, there should be a site of infection with swelling, bony tenderness, or erythema.  The lab work will show elevated WBC, CRP and ESR. Blood cultures may or may not be positive. Wound cultures are often times polymicrobial. A bone biopsy that correlates with the blood culture would be nice, but it happens less than half of the time.
 Imaging can be helpful. X ray will show osteomyelitis or a periosteal reaction after about 2 weeks and 50% bone loss. MRI can detect osteomyelitis within 3-5 days of infection. It can find necrotic bone, sinus tracts, and abscesses. Three-phase technetium-99 bone scintigraphy can also find osteomyelitis within a few days of disease onset. PET is affective as well, but expensive and not widely available.
   Treatment would ideally be driven by culture results. Often times this information is not available and broad spectrum empiric antibiotics are used. Children should be covered for S. aureus, or MRSA, if suspected. S. aureus can be treated with nafcillin, oxacillin, or cefazolin. MRSA can be treated with vancomycin. Clindamycin can be used in anaerobes. Ticarcillin/clavulanate can be used for enterobacteriaceae (E. coli) and anaerobes. Piperacillin/tazobactam can be used for enterobacteriaceae and P.aeruginosa. Fluoroquinolones are used in patients with penicillin allergies or diabetic foot ulcers.