Abstract
We report the rare case of a patient presenting with bacteremia caused by Paenibacillus pasadenensis. A 78-year-old female with 30 years’ history of hypertension was admitted because of chest discomfort on exertion. She was diagnosed as having sick sinus syndrome and implanted with a pacemaker. She developed a fever of over 100 °F on day 2 after the procedure. After 48 hours of incubation, blood cultures were positive for a Gram-“negative” Bacillus sp., which remained unidentified by conventional bacteriological methods because the biochemical profiling data did not match any preexisting pattern. The bacterial colonies tested “partly positive” by Gram staining and appeared to be forming spores, and Ryu’s method using 3% KOH did not show any evidence of stickiness, which indicated that further biochemical and molecular analyses should be performed. Mass spectrometry and 16S rRNA gene sequencing finally enabled the identification of the pathogenic bacterium as P. pasadenensis. The patient did not respond to cefazolin, requiring the temporary removal of the pacemaker on day 12. She then responded to cefmetazole, ceftazidime and levofloxacin despite the pacemaker reimplantation on day 20 and was discharged on day 37. P. pasadenensis was first isolated from clinical samples and described in 2010 and was mainly associated with bloodstream infection. This is, to the best of our knowledge, the first description in the Japanese literature. Modern biochemical and molecular analyses of bacterial colonies are very powerful tools for the identification of otherwise unknown species, whereas basic procedures such as Gram staining or Ryu’s method could also provide us with important clues toward precise diagnosis.
