Cause:
Staph. aureus(60%), tuberculosis, group A strep, haemophilus, pneumococcus, salmonella, gonorrhea, enterobacter group, fungal; in neonates, group B strep, E. coli; pseudomonas in drug addicts, in sneaker wearers who step on nails
Pathophys:Bacteremia results in bacteria picked up by slow blood flow area of metaphysis; infection can’t penetrate epiphysis so moves down bone via haversian and Volkmann’s canals; may rupture through thin metaphyseal cortical bone; sequestration of dead bone prolongs recovery. Persistence may be a result of intracellular survival, esp w tuberculosis
85% of cases are children; salmonella osteomyelitis very frequent in sickle disease; also common in diabetics w foot ulcers (Nejm 1994;331:854) and pts w decubitus ulcers (Arch IM 1983;143:683)
Sx:Localized pain; antalgic use of limb; fever
Si:Often nothing besides fever; may have local redness, swelling, drainage; if can probe an ulcer to bone, likelihood increased
Altered (increased or decreased) epiphyseal growth of 1 limb due to changes in blood supply, Brodie’s abscess, sequestration and reactivation years later, acute glomerulonephritis (Ann IM 1969;71:335), amyloidosis, local epidermoid carcinoma in 0.5%
Lab:
Bact:Blood cultures; if neg, bone aspiration positive in 60%, bone biopsy positive in 90%. Culture of draining sinus unreliable
Hem:ESR >70 (but not always—Nejm 1987;316:763)
Xray:MRI 90% sens and specif; or CT very sensitive, esp early before changes on plain films
Plain films may show gross deformities with lytic and blastic activity after 2-4 wk
Bone scan positive within weeks, 50-75% false pos, 70-90% sens (J Gen Int Med 1992;7:158)
Rx:Appropriate long-term parenteral antibiotics (see Table 18.2) and surgical removal of sequestrum
Table 18.2 Antibiotic Treatment of Osteomyelitis in Adults
| Microorganisms Isolated | Treatment of Choice | Alternatives |
|---|---|---|
| S. aureus | ||
| Penicillin-sensitive | Penicillin G (4 million units every 6 hr) | First-generation cephalosporin (e.g., cefazolin, 2 g every 6 hr), clindamycin (600 mg every 6 hr), or vancomycin (1 g every 12 hr) |
| Penicillin-resistant | Nafcillin (2 g every 6 hr) | First-generation cephalosporin, clindamycin (as above), or vancomycin (as above) |
| Methicillin-resistant | Vancomycin (1 g every 12 hr) | Teicoplanin (400 mg every 24 hr; first day, every 12 hr intravenously or intramuscularly)‡ |
| Various streptococci (group A or B ß-hemolytic or Streptococcuspneumoniae) | Penicillin G (4 million units every 6 hr) | Clindamycin (as above), erythromycin (500 mg every 6 hr), vancomycin (as above), or ceftriax-one (2 g once a day) |
| Enteric gram-negative rods | Quinolone (ciprofloxacin, 750 mg every 12 hr orally) | Third-generation cephalosporin (e.g., ceftriaxone, 2 g every 24 hr) |
| Serratia or Pseudomonas aeruginosa | Ceftazidime (2 g every 8 hr) (with aminoglycosides for at least the first 2 wk)§ | Imipenem (500 mg every 6 hr), piperacillin–tazobactam (4 g and 0.5 g, respectively, every 8 hr), or cefepime (2 g every 12 hr) (with aminoglycosides for at least the first 2 wk)§ |
| Anaerobes | Clindamycin (600 mg every 6 hr intravenously or orally) | Amoxicillin–clavulanic acid (2.0 and 0.2 g, respectively, every 8 hr) or metronidazole for gram-negative anaerobes (500 mg every 8 hr) |
| Mixed aerobic and anaerobic microorganisms | Amoxicillin–clavulanic acid (2.0 and 0.2 g, respectively, every 8 hr) | Imipenem (500 mg every 6 hr)¶ |
* All antibiotic treatments are given intravenously unless otherwise stated.
† In Europe, fludoxacillin is the treatment of choice.
‡ Teicoplanin is currently available only in Europe.
§ Aminoglycosides may be given once a day or in multiple doses.
¶ Imipenem should be given when infection is due to aerobic gram-negative microorganisms resistant to amoxicillin–clavulanic acid.
Reproduced with permission from Lew DP, Waldvogel FA. Osteomyelitis. Nejm 1997;336:999–1007. Copyright 1997, Mass. Medical Society, all rights reserved.