Pathogen of spondylodiscitis

Non-specific spondylodiscitis is primarily caused by the bacterium Staphylococcus aureus. The spread of the pathogen can occur either by the internal (endogenous) or external (exogenous) route.In the endogenous pathway, the bacteria move from an infection in the body, beyond the vertebral body, into the bloodstream and from there to the affected parts of the spine (hematogenic). The pathogens can be transmitted both through the venous (“leading to the heart“) and the arterial (“leading away from the heart”) bloodstream.

Inflammation can also be triggered by infected lymph fluid (lymphogenic). Endogenous excitation often occurs in patients with an immune system deficiency due to e.g. diabetes mellitus, chronic alcohol and drug abuse, tumor diseases or preceding chronic inflammation. In addition, there is the exogenous route.

Here, the source of infection lies in the affected vertebral body or the intervertebral disc itself. Impurities or non-sterile work during operations or injections close to the spinal column channel the pathogens directly into the body. In some cases (10-15%), exogenous infections involve an MRSA pathogen (methicillin-resistant staphylococcus aureus), which has become a major problem in many hospitals due to its insensitivity (resistance) to many antibiotics.

In addition to Staphylococcus aureus (36%), which belongs to the staphylococci, Gram-negative bacteria, such as Escheria coli (23%) or Pseudomonas aeruginosa (5%), which occur in the intestine, cause unspecific spondylodiscitis. Furthermore, streptococci such as Streptococcus sanguis are detectable in 19% of cases. Fungi and parasites are extremely rare as pathogens, and therefore not mentioned by name!

The clinical picture of specific spondylodiscitis is caused by tuberculosis pathogens, usually the mycobacterium tuberculosis. The infection always occurs via the endogenous route. HIV-positive patients with tuberculosis have a particularly high risk of contracting a specific spondylodiscitis.

Alcoholism, diabetes mellitus, tumor diseases are important concomitant diseases of a patient, which can promote the development of spondylodiscitis.

Open injuries that lead to local infection can cause bacteria to settle.
During spinal surgery, bacteria can enter the intervertebral disc or the vertebral body through the surgical access, e.g. during disc surgery, stiffening surgery (spondylodesis), discography and many more. Since such an infection can never be completely ruled out, even when all hygiene regulations are observed, a thorough explanation of the risk of infection during surgery and the possible consequences of such an infection is given in advance of a planned spinal surgery.
Fortunately, such infections are rare.
The bright representation of the vertebral body shows the pus
Discitis. The adjacent intervertebral discs are also affected by the infection.
Representation of a healthy vertebral body
Muscle ileopsoas; no abscess of subsidence visible yet
Spinal Canal
Healthy vertebral body
Spondylodiscitis. The collapse of the vertebral body is known to occur in severe infection

In addition to the symptoms described, the patient’s medical history (anamnesis) can provide decisive indications of the presence of spondylodiscitis.

In particular, it is important to find out whether infections have recently occurred in other organs of the body and how they have been treated. Furthermore, it is of particular interest whether a spinal operation was performed recently or even a long time ago. The standardized examination in case of an inflammatory process in the spinal column includes a blood test with determination of the inflammation values (see above).

If the symptoms (back pain and possibly fever) are consistent with the determination of elevated inflammation values, then there is a reasonable suspicion of a vertebral body infection. The x-ray of the suspected spinal section is also one of the initial diagnostic measures for spondylodiscitis. In very advanced cases of infection, changes in the normal radiological image of the vertebral body (shading, brightening) may be present.

The disc height may be reduced. In very advanced cases of spondylodiscitis, destruction of the vertebral body (osteolysis) or collapse of the vertebral body due to inflammation may be observed. These are very late signs of a severe vertebral body infection.In many cases the X-ray image can be completely inconspicuous.

In order to prevent such a degree of vertebral body destruction by timely therapeutic countermeasures, early diagnosis is of crucial importance. MRI (magnetic resonance imaging, NMR, especially of the lumbar spine) can reveal typical changes of a vertebral body and intervertebral disc infection much earlier than X-rays, as the pus that has formed can be detected as accumulation of fluid. It is also possible to assess the strength and spread of the infection. For this reason, if there is a justified suspicion of a vertebral body infection, an MRI examination of the respective region (cervical, thoracic, lumbar) should always be performed at an early stage.