Following are the causes of repeated infection at the surgical site which is difficult to eradicate till the primary cause is taken care of;
1) An unabsorbable suture; this acts as a foreign body and any infection would not be eradicated in it's presence. So wound would need an exploration and removal of suture.
2) An infection like tuberculosis, which is not uncommon in his age group, and may get better by antibiotics, but would need specific treatment for it. A specific culture for the tuberculosis need to be done to confirm the cause.
3) An infection like MRSA; a culture test identifies it.
4) A sinus formation; this is a pocket of infection and bacteria stay in the cavity underneath the deeper tissue. This also need surgical exploration.
As you mentioned a second opinion may be sought or you may discuss these possibilites with his surgeon.
Please feel free for your follow up questions.
Various blood tests have been undertaken to try and identify the cause of infection so I hope MRSA, Tuberculosis and/or other infections would have been spotted.
I am not sure what suturs were used but there was a disc replacement and possibly fusing of one spinal joint.
If the original syst had not been fully removed could this also be the source of ongoing infection?
Since the CT scan is normal, a residual cyst is quite unlikely. A cyst would also not be likely to be responsible for the recurrent infection. The sutures are used for closing the soft tissue (muscles and fascia) in the disc surgery and they are not uncommon cause for the recurrent infection.
It is privilege assisting you.
One last question.
In the UK the NHS advocate a conservative approach/policy and tend to wait and see what happens rather than undertake further surgeries. As it has been 18 months since the operation should e be insisting of a more proactive approach include further exploration or other surgery?
Yes, Definitely. He needs more proactive approach like re-exploration as any further antibiotic course is not much likely to stop the recurrence.
It is pleasure and privilege assisting you.