October 2005

This is a composite of two nearly identical patients.

A 16-year-old boy is admitted for evaluation and treatment of some drainage from a site of recent surgery. His past medical history is significant for having been diagnosed with bone cancer after a pathologic fracture of the distal left femur several months earlier (figures 1 & 2) and underwent a limb-sparing procedure using an artificial knee and distal femur (figure 3). He had no fever or chills. He is receiving chemotherapy for the cancer, and is otherwise stable.

Examination revealed normal vital signs and some yellowish material draining from the scar (figure 4) that could be expressed with gentle pressure (figure 5). A complete blood count was normal and cultures of drainage material are pending.

What’s Your Diagnosis (Cause)?

1. Sterile abscess
2. Pseudomonas aeruginosa
3. Eikenella corrodens
4. Staphylococcus aureus

Answer

This turned out to be chronic osteomyelitis, which is usually due to Staphylococcus aureus, D. It is usually associated with trauma and/or implanted hardware, such as prosthetic devices. Uncommonly, it may occur as a result of inadequate therapy (dose too low/duration too short or the wrong antibiotic).

One must now consider methicillin-resistant Staphylococcus aureus (MRSA) with all these infections when considering choice of empiric therapy. In some patients, especially trauma patients and cancer patients, gram-negative rods and unusual organisms may be recovered.

Even though S. aureus is most common in the patient presented, Escherichia coli was recovered. These infections usually become apparent after a few weeks following surgery; however, months to years may pass before symptoms are noted. The patient may complain of intermittent dull pain and drainage from the incision site. Blood tests such as cultures and complete blood counts are of little value.

However, plain radiographs will often reveal bone destruction from necrosis. One may see an abscess develop at the site called a Brodie’s abscess (figure 6), named for Sir Benjamin Collins Brodie (1783-1862), an English surgeon. Treatment generally involves removal of any remaining hardware and debridement of necrotic bone (figure 7), along with prolonged antibiotics in order to clear the infection. Of course, removing the hardware in a patient like the one presented might mean loss of the limb. However, in this case, the prosthesis was removed and a spacer was used while the patient underwent prolonged IV antibiotic therapy, and another prosthesis was successfully reimplanted with good long-term follow-up.

Other methods of treatment have included irrigation with antibiotic-containing solutions and implanting antibiotic-impregnated polymethylmethacrylate beads. However, these techniques have not been shown to add benefit to conventional therapy.

Regarding the other choices, Pseudomonas aeruginosa is always a concern in cancer patients, but is still not nearly as likely as S. aureus. Eikenella corrodens, a gram-negative mouth anaerobe, is a member of the HACEK group of organisms, which are known to have similar growth characteristics and mostly cause endocarditis. However, it is possible for these organisms to also cause bone infections.

An excellent, brief review of chronic osteomyelitis can be found by Otto M. Ramos. (Pediatr Infect Dis J. 2002;21:431-432.)

Thoughts on the Gulf Coast

I’m sure most of you have friends and/or family in the Gulf Coast area affected by Hurricane Katrina. All of my surviving relatives on my father’s side are in Houma, just south of New Orleans and I have a maternal aunt in Brookhaven, Mississippi, just about 100 miles due north of New Orleans. Surprisingly, all came through it well. They are the lucky ones. We have all seen up close and in painful detail the effect on many others displaced by the storm. Many of you had plans on vacationing or attending meetings in the area that are now cancelled or at least on hold.

One of my favorite meetings, the Uniformed Services Pediatric Seminar (USPS), an AAP-sponsored meeting and hosted next year by the department of pediatrics at Keesler Air Force Base, was to be held in Biloxi, Miss., next March. However, it may or may not happen now. You can probably find out by checking it out on the AAP CME Web site. I will also update the USPS situation in this column each month.

By the way, the best information I can find indicates that during the time that the storm dominated the news, 10 more soldiers were killed in action, nine in Iraq and one in Afghanistan. This has taken such a back seat that I had to seek out the information by scrolling the various Internet news sources.

Lastly, I hope my old friend Russ Steele, vice chairman of pediatrics at Louisiana State University School of Medicine in New Orleans, will soon be back out in the French Quarter, playing trombone with his jazz band, Doctor Jazz (figure 8). That’s when I’ll know things have gotten back to normal in the Crescent City.