SLR - March 2011 - David Pougatsch
Reference: Senneville E, Morant H, Descamps D, Dekeyser S, Beltrand E, Singer B, Caillaux M, Boulogne A, Legout L, Lemaire X, Lemaire C, and Yazdanpanah Y. Needle Puncture and Transcutaneous Bone Biopsy Cultures Are Inconsistent in Patients with Diabetes and Suspected Osteomyelitis of the Foot. Clinical Infectious Diseases. (2009). 48:888-93.
Scientific Literature Review
Reviewed by: David Pougatsch, DPM
Residency Program: Cedars-Sinai Medical Center; Los Angeles, CA
Podiatric Relevance:
This multi-center, prospective trial attempts to find another way of obtaining specimen for culture, namely needle puncture, to aid in diagnosing osteomyelitis in diabetic foot infections other than the widely-used culture swab and the more invasive bone biopsy. Although the bone biopsy is still the gold standard for diagnosing osteomyelitis, the means of obtaining it are usually via surgical debridement. The authors attempted to present another means of collecting specimens which could be used to diagnose osteomyelitis in non-surgical cases of diabetic foot ulcerations.
Methods:
Inclusion criteria were patients a minimum of 18 years of age, with a diagnosis of type 2 diabetes mellitus, with a foot ulcer over a bony prominence, and with radiological abnormality suggestive of osteomyelitis. Exclusion criteria were previous antibiotic therapy within the last 2 weeks, gangrene, having immediate need for amputation, or lacking palpable pedal pulses. Over a 20 month period, 451 patients presented with diabetic foot ulcers, of which only 31 patients qualified to be part of the study group.
Patients underwent multiple methods of testing to determine osteomyelitis within their diabetic foot wounds. Swab samples were collected by first cleansing wound with iodine and normal saline prior to sample being obtained, so as to not swab potential contaminants. Needle puncture sample was collected transcutaneously from the site of the radiographic abnormality at the bony prominence. The needle was inserted at least 20mm from the periphery of the ulceration to avoid colonizing flora and then directed towards the site of the bony abnormality utilizing radiography. Then utilizing at an 18-gauge needle attached to a syringe with 1mL of sterile saline, fluid from the affected area was aspirated. Transcutaneous bone biopsies were performed in an identical fashion by both an orthopedist and radiologist in surgical and radiological environments, respectively. After disinfecting the surrounding skin, an 11-gauge biopsy needle was inserted into an incision made 20mm from the periphery of the ulcer. All samples were sent for aerobic and anaerobic culture.
Results:
Culture results were positive in 18 (58%) of the needle puncture specimens, 21 (68%) of the bone biopsy specimens, and 30 (97%) of the culture swab specimens. All needle puncture and bone biopsy specimens had negative Gram stain results. Of the culture positive bone biopsy specimens, only 13 also had culture positive needle punctures. Only 10 patients had identical bone biopsy and needle puncture specimen culture results. Bone bacteria were isolated in only 7 of 21 bone biopsy specimens with positive culture results. If needle puncture alone were used to determine osteomyelitis, 5 (16%) patients with negative bone biopsy specimen cultures would have received unnecessary antibiotic therapy, while 8 (38%) patients with positive bone biopsy specimen culture results would not have been treated, as their needle puncture was considered negative. Most of the inconsistencies were associated with Gram-negative rods such as Pseudomonas and Proteus species. The number of bacterial isolates were 1.35, 1.32, and 2.51 for bone biopsy, needle puncture, and culture swab methods, respectively.
Conclusion:
While needle puncture aspiration might be a good technique and can localize nearly the same amount of bacterial isolates as bone biopsy, the affinity for determining the actual bone quality and the likelihood of osteomyelitis, is unreliable. The amount of variability seen with the considerably high percentage of false positives and false negatives warrants that this technique not be used to solely assist in diagnosing osteomyelitis in diabetic foot ulcerations. The gold standard continues to be bone biopsy.