**7.2 Microbial agents**

The most common causative agents of spinal infections are *Staphylococcus aureus* and *Staphylococcus epidermidis*, gram negative organisms and in general anaerobe bacteria. In infants the most common agents are *Staphylococcus aureus*, *Streptococcus agalactiae* and *Escherichia coli* and in childhood *Staphylococcus aureus*, Staphylococcus pyogenes and Hemophilus influenzae. *Staphylococcus aureus* is the most common causative agent in hematogenous osteomyelitis in patients of all ages [19]. *Mycobacterium tuberculosis* can cause Pott's disease and skeletal tuberculosis which nowadays are extremely rare. Fungal origin of spinal infection is rarely found and particularly include Aspergillus spp., Candida spp., and *Cryptococcus neoformans* [17].
