Two cases of diskitis attributable to anaerobic bacteria in children

Diskitis, an inflammation of the intervertebral disk, is generally attribut able to Staphylococcus aureus and rarely Staphylococcus epidermidis, Kingel la kingae, Enterobacteriaciae, and Streptococcus pneumoniae. In many cases, no bacterial growth is obtained from infected intervertebral discs. Althou gh anaerobic bacteria were recovered from adults with spondylodiscitis, the se organisms were not reported before from children. The recovery of anaero bic bacteria in 2 children with diskitis is reported. Patient 1. A 10-year-old male presented with 6 weeks of low back pain and 2 weeks of low-grade fever and abdominal pain. Physical examination was norm al except for tenderness to percussion over the spine between thoracic vert ebra 11 and lumbar vertebra 2. The patient had a temperature of 104 degrees F. Laboratory tests were within normal limits, except for erythrocyte sedim entation rate (ESR), which was 58 mm/hour. Blood culture showed no growth. Magnetic resonance imaging with gadolinium contrast revealed minimal inflam matory changes in the 12th thoracic vertebra/first lumbar vertebra disk. Th ere was no other abnormality. A computed tomography (CT)-guided aspiration of the disk space yielded bloody material, which was sent for aerobic and a naerobic cultures. Gram stain showed numerous white blood cells and Gram-po sitive cocci in chains. Cultures for anaerobic bacteria yielded heavy growt h of Peptostreptococcus magnus, which was susceptible to penicillin, clinda mycin, and vancomycin. The patient was treated with intravenous penicillin 600 000 units every 6 hours for 3 weeks, and then oral amoxicillin, 500 mg every 6 hours for 3 weeks. The back pain resolved within 2 weeks, and the E SR returned to normal at the end of therapy. Follow-up for 3 years showed c omplete resolution of the infection. Patient 2. An 8-year-old boy presented with low back pain and low-grade fev er, irritability, and general malaise for 10 days. He had had an upper resp iratory tract infection with sore throat 27 days earlier, for which he rece ived no therapy. The patient had a temperature of 102 degreesF, and physica l examination was normal except for tenderness to percussion over the spine between the second and fourth lumbar vertebrae. Laboratory tests were norm al, except for the ESR (42 mm/hour). Radiographs of the spine showed narrow ing of the third to fourth lumbar vertebra disk space and irregularity of t he margins of the vertebral endplates. A CT scan revealed a lytic bone lesi on at lumbar vertebra 4, and bone scan showed an increase uptake of (99m)te chnetium at the third to fourth lumbar vertebra disk space. CT-guided aspir ation of the disk space yielded cloudy nonfoul-smelling material, which was sent for aerobic and anaerobic cultures. Gram stain showed numerous white blood cells and fusiform Gram-negative bacilli. Anaerobic culture grew ligh t growth of Fusobacterium nucleatum. The organism produced beta -lactamase and was susceptible to ticarcillin-clavulanate, clindamycin, metronidazole, and imipenem. Therapy with clindamycin 450 mg every 8 hours was given pare nterally for 3 weeks and orally for 3 weeks. Back pain resolved within 2 we eks. A 2-year follow-up showed complete resolution and no recurrence. This report describes, for the first time, the isolation of anaerobic bacteria f rom children with diskitis. The lack of their recovery in previous reports and the absence of bacterial growth in over two third of these studies may be caused by the use of improper methods for their collection, transportati on, and cultivation. Proper choice of antimicrobial therapy for diskitis ca n be accomplished only by identification of the causative organisms and its antimicrobial susceptibility. This is of particular importance in infectio ns caused by anaerobic bacteria that are often resistant to antimicrobials used to empirically treat diskitis. This was the case in our second patient , who was infected by F nucleatum, which was resistant to beta -lactam anti biotics. The origin of the anaerobic bacteria causing the infection in our patient is probably of endogenous nature. The presence of abdominal pain in the first child may have been attributable to a subclinical abdominal path ology. The preceding pharyngitis in the second patient may have been associ ated with a potential hematogenous spread of F nucleatum. P magnus has been associated with bone and joint infections. This report highlights the impo rtance of obtaining disk space culture for aerobic and anaerobic bacteria f rom all children with diskitis. Future prospective studies are warranted to elucidate the role of anaerobic bacteria in diskitis in children.