Mycobacterium phlei Vertebral Osteomyelitis

Objective: A report of an instance of vertebral osteomyelitis secondary to an uncommon pathogen, Mycobacterium phlei. Summary: Mycobacterium phlei is a rapidly growing nontuberculous osteomyelitis which is typically nonpathogenic with only four reported cases of human infection. Diagnosing infections related to nontuberculous mycobacteria (NTM) is difficult and can often be delayed as conventional microbiologic tests are inadequate. Currently, there are no consensus guidelines concerning the treatment of vertebral osteomyelitis caused by NTM. A 45-year-old man presented with chronic back pain and bilateral lower extremity radicular symptoms status-post lumbar fusion with previous deep infection. CT scan demonstrated incomplete union after fusion. He underwent irrigation and débridement on March 15, 2016, with tissue culture and biopsy. Given negative cultures and completion of a 6-week course of intravenous antibiotics, on May 3, 2016, he went for implant removal and repeat instrumentation. During the same hospitalization, deep spinal fluid acid-fast bacilli culture from March 15, 2016, came back positive at 8 weeks, identified as Mycobaterium phlei. He was started on an empiric 4-drug regimen for NTM which he continued for 12 months. There has been no recurrence of infection to date. Discussion: This case serves as the first description of M. phlei osteomyelitis of the spine and as a reminder that proper diagnosis of infectious etiologies is necessary for adequate treatment.