Introduction

Post spinal surgery infection is not uncommon and is considered as one of the most annoying complication following surgery on the spine. It ranged from 0 to 17% [1, 2]. Many risk factors may predispose to the development and worsening of post-operative infection. Patient’s related factors are diabetes, rheumatoid, obesity, renal failure, old age, alcohol addiction, pre-operative epi-dural steroid injection and smoking. These form the most important risk factors [3,4,5]. Pre-operative knowledge about these factors, especially if treatable, can greatly modify the post-operative results. Intraoperative complications, foreign body implantation, excessive tissue devascularization, haemorrhage, dural injury, esophageal perforation and prolonged procedures can result in post-operative infection [6, 7]. The major burdens of post spinal surgery infection are time and money consuming effects. Infections have a considerable effect on post-operative morbidity and mortality [8]. Recently, post spinal surgery infection was subtyped into superficial, deep and organ space infection. Infections of the skin and subcutaneous tissues are considered as superficial infections which may occur within 1 month from surgery and associated with infected discharge which gives positive results on cultures. Infections of the fascia and muscles are the targets of deep infection with infected discharge or abscess formation. Infections deep to the muscles are considered as organ space infection with psoas abscess, discitis, spondylitis, or epi-dural abscess formation [9]. The gold standard is to prevent post-operative infection but if it occurs, early diagnosis and ideal management are mandatory to achieve a good recovery. Early diagnosis depends on clinical evaluation, laboratory and radiological investigations [10]. The aim of this study was to identify the possible risk factors, preventive measures, diagnostic tools and the ideal management procedures.

Materials and methods

This is a retrospective study which was carried out on 35 patients operated upon (either primary or revision) for variable spinal lesions from 2006 till 2016 and complicated by post spinal surgery infection. No patient was operated upon for primary pre-existing spinal infection or congenital lesions. On presentation, the patients were diagnosed to have post-operative infection by clinical examination, laboratory and radiological investigation. All patients were re-admitted to the hospital even those with superficial infections for fear of spread of infection to the deep layers where the urgent management was done. During the hospital stay, the patients were followed up laboratory and radiological investigations. The laboratory investigations included complete blood picture, blood sugar, culture and sensitivity from the wound, renal and liver function tests and C-reactive protein. The radiological investigations included plain X-ray, CT scan and MRI. After complete healing of infection, the patients were followed up for at least 6 months after discharge from the hospital for fear or recurrence of infection. Summary of the clinical data of cervical, dorsal and lumbar patients was categorized in Tables 1, 2 and 3 respectively.

Table 1 Summary of the clinical data of cervical patients
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Table 2 Summary of the clinical data of dorsal patients
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Table 3 Summary of the clinical data of lumbar patients
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Results

As regard:

The level of affection: 13 patients had cervical lesions, 4 had dorsal lesions and 18 had lumbar affection.

The age ranged from 22 to 76 years with mean of 52.7 years.

The sex: The patients were 20 males and 15 females.

Pre-operative risk factors were evident in 27 patients. Diabetes (in 12 patients) and obesity (in 8 patients) were the most common risk factors.

Primary lesion: cervical disc prolapse (8 patients) was the most common lesion in the cervical region group, whereas lumbar disc prolapse (12 patients) was the most common lesion in lumbar group.

Duration and type of operation: ranged from 45 to 200 min. Discectomy either cervical or lumbar (20 patients) was the most common operative technique in the infected group.

Intra-operative complications: 6 patients suffered from complications (durotomy in 5 patients and right common iliac artery injury in one patient).

Foreign body implantation: was done in 19 patients. Cages, plates and screws were the most common foreign body implanted.

Post-operative complications: were observed in 13 patients. Esophageal perforation was the most dangerous and devastation complication and was faced after tracheostomy.

Lucid interval (between the primary surgery and the diagnosis of infection): ranged from 5 days to 4 months.

Type of infection: superficial infection was encountered in 12 patients and deep infection was diagnosed in 19 patients, whereas combined infection occurred in 4 patients.

Management: surgical management that needs general anaesthesia was done in 22 patients whereas conservative management was provided to 13 patients. The plates were removed in 3 cases in which poor response to suction irrigation was encountered. We observed that the use of irrigation with CSF leak would not delay the healing or prolong the leak.

Re-hospitalization stay: ranged from 10 days to 3 months.

Fate: out of 35 cases, only one patient died from the complications of infection.

Discussion

The number of spinal operations had greatly increased due to many factors. Increased awareness about the spine biomechanics and development of many devices that facilitate and increase the accuracy and safety of new techniques are among these factors [11]. Consequently, the post-operative complications including post spinal surgery infections have increased. Post spinal surgery infections result from reaction and integration of patient, hospital and surgery team factors. Great efforts should be directed to prevent the morbidity and mortality sequelae of infections [12]. The great importance of post spinal infection is the economic burdens related to re-admission of the patients or revision surgeries [13, 14].

The mean age in this study is 52.7 years which is comparable with the age of patients with post spinal infections in literature which is above 48 years, and this may be due to decreased immunity with age [15, 16].

Pre-operative risk factors played a very significant role in the occurrence, type and management of post spinal infections. Diabetes and obesity were the most common risk factors detected in our study, and this observation is matching with other authors. Some authors reported increased incidence of post-operative infection with previous history of epidural corticosteroid injection, rheumatoid, renal failure, old age and alcohol addiction [5, 17, 18].

Increased incidence of infection with foreign body implantation was observed, and this infection is more resistant to treatment. This observation was explained in a study proofed that these organisms are firmly adherent to the surface of the foreign body forming the biofilm leading to colonization of organisms leading to antimicrobial resistance [19].

In many studies, post-operative infection usually occur in the first 4 weeks after surgery but late superficial or deep infections may occur even after 1 year from surgery [20,21,22].

Intra- or post-operative complications may be the precipitating factors and largely affect the development of post-operative infections especially if being major or devastating complications. In our study, we faced one major intra-operative complication in the form of right common iliac artery injury in a case operated upon for recurrent lumbar disc prolapse causing massive bleeding in the surgical site and forming a large retro-peritoneal haematoma. We immediately turned the patient to his left side, and a right retro-peritoneal approach was done. Direct compression was applied on the site of the tear, evacuation of the haematoma and blood transfusion. Within 30 min, the vascular surgeon reached the operating room and successful repair of the arterial tear was done. The patient was saved but suffered from right lower limb mono-paresis immediate postoperative. Two weeks post-operatively, the patient suffered from discitis and retroperitoneal abscess. The patient was operated upon through the retro-peritoneal approach to evacuate the abscess and do curettage of disc space and insertion of irrigation suction system. The infection healed after 5 weeks, and the paresis improved within 2 months.

Two patients suffered from post-operative esophageal perforation as a complication of tracheostomy. The first one was managed conservatively at the start by insertion of nasogastric tube and total parenteral nutrition and antibiotics for 3 weeks which failed to control the infection. Under general anaesthesia, removal of plate and screws, insertion of suction-irrigation system and feeding gastrostomy were done. Despite of all these, the patient deteriorated till death occurred after 3 months from perforation. The second one was managed surgically from the start by direct esophageal repair by cardiothorathic team, insertion of irrigation-suction system and total parenteral nutrition for 25 days. Complete healing of infection was encountered in this patient without the need to remove the plate and screws.

In our study, we managed patients with post-operative superficial infections by re-hospitalization, radiological and laboratory investigations especially blood picture, C-reactive protein and culture and sensitivity from the wound. Maximum dose combination parenteral antibiotics according to results of culture and sensitivity were given for at least 2 weeks. Local application of Betadine and Rifamycin powder was done in all patients. Patients with deep infections were managed surgically by opening the surgical site, evacuation of the abscess, curettage of the disc space if no cage was present, removal of implants (only in 3 cases), extensive wash with betadine and saline, application of antibiotic powder and insertion of irrigation-suction system. Five hundred cubic centimeter normal saline with 1 g vancomycin and 80 mg gentamycin was infused through the irrigation system every 6 h and kept inside for 1 h then drained. These cycles of irrigation followed by suctions were repeated for at least 2 weeks. From the start, maximum dose combination-sensitive parenteral antibiotics were given for at least 1 month followed by intra-muscular and oral antibiotics for another 2 months. We faced one case with fungal discitis that need parenteral antifungal and antibiotics for 11 weeks followed by oral treatment for 3 months. We found that Staphylococcus aureus was the most common organism causing post-operative infection (Table 4).

Table 4 Bacterial cultures
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Prophylactic measures directed for prevention of post spinal surgery infection were proved to decrease the incidence of infection by many authors. Our usual plan for prophylaxis is to follow these measures. These include sterile operating rooms, pre-operative microbial screening of patients and decolonization of any septic focus, glycemic control, smoking stoppage, antiseptic showers, pre-operative antibiotics, Betadine and saline irrigation at the surgical site and Vancomycin topical application [23,24,25]. Some authors used the peri-operative (intra-operative and post-operative) local antibiotics irrigation for 1–7 days and proved the decrease in the rate of post-operative infections [26,27,28].

Conclusion

Post spinal surgery infection is a devastating complication that needs multi-modalities for prevention and control. Neutralization of the pre-operative risk factors can dramatically reduce the post-operative infections. Once diagnosed, the patients with infection must be hospitalized and extensive management should be applied. Irrigation-suction application is a very effective and safe measure in treating infections, so the need to remove the implanted grafts is limited.