The most common organism causing acute osteomyelitis is

Microorganisms that Cause OsteomyelitisOrganismCommentFrequently Encountered BacteriaStaphylococcus aureusMost likely bacterial pathogen. Aggressive, invasive. Often metastatic foci with bacteremia Consider surgery earlyStaphylococci other than S. aureus (coagulase-negative) Usually associated with foreign material or implantsBiofilm productionStreptococciMay spread rapidly through soft tissuesEnterobacteriaceae (Escherichia coli, Klebsiella spp., others) Considerable variation in antibiotic susceptibility Increasing antibiotic resistance with overuse May become resistant to antibiotics during therapyPseudomonas aeruginosaIncreasingly resistant to the antibiotics. The frequent successor to other bacteria when initial therapy fails. Maybe related to contaminationUnusual OrganismsAnaerobic bacteriaUsually mixed with aerobic bacteriaMay be synergisticSurvival dependent on devitalized tissue Baonella henselaeAssociated with cat scratches and probably with fleasBrucella speciesProminent in developing countries, especially with unpasteurized milkFungiCandida the most likely genusConsiderable variation in susceptibility, depending on species Surgery may be helpful if the infection is invasiveMycobacterium tuberculosisMay involve any boneVeebral osteomyelitis common in some countriesMycobacteria other than M. tuberculosisNeed special culture media to recoverVirusesAssociated with some viral infections, including varicella and variolaRef: Harrison's infectious disease 2nd edition, p260