Neurosurgery surgical site infections remain an intense reason for morbidity and mortality11. The quoted infection rate ranges from 5-27% with most between 5% and 15%7,11. The variations in infection rates may be due to different study designs. The incidence of infection is either related to the number of patients, types of surgeries and presence of implants. Clearly, infection rates per patient will be higher than infection rates per procedure, as with any series many patients will have multiple procedures12. In our study, we included all neurosurgical procedures without any sub-categorization.
Different studies have pointed to a variety of factors that play a role in post-operative infection. Age, gender, skin condition, pathology, aetiology and immunological status of the patient have all been implicated7. Surgical factors that have been studied are the length of postoperative hospitalization3,10, duration and type of surgery, number of revisions, and type of suture material used, the presence of implants, aseptic technique and prophylactic antibiotics7. We had covered all factors in our study.
The role of prophylactic antibiotics remains ambiguous and undefined. In a recent control study7, the infection rate was 6.25% in patients without antibiotic prophylaxis as compared with 2.56% in patients with antibiotic prophylaxis7, 9. This difference was not found to be statistically significant. At present, the benefit of perioperative antibiotic prophylaxis remains unestablished5, but most of the Neurosurgical centres have standard preoperative antibiotic policies9. Our patients were given one dose of antibiotic pre-operatively and three doses post-operatively for cranial cases, one dose of antibiotic pre-operatively and one dose of antibiotic post-operatively for spinal cases.
The duration of surgery had no effect on infection rates as reported in the literature. The duration of the surgery in our infected patient was around two and half hours, whereas other patients with longer duration of surgery did not contract any infection.
The role of strict aseptic pre-operative and operative practices in preventing post-operative infections were demonstrated in the study published by Choux et al13. In his study, the infection rate in shunt surgery in the same hospital with the same staff between two periods 1978-1982 and 1983 were demonstrated13. The only difference being strict aseptic precautions and limited theatre personnel. There was a significant difference in post-operative infection rates 15.56% in 1978-82 and 0.33% in 198313..All remaining parameters such as age, gender, pathology, type of shunt, shunt material, surgeon and a number of revisions caused no significant differences. Choux et al13 also stated that it was possible to reach a nearly zero shunt infection rate.
The association between re-surgery and post-operative infection rates is unsettled in literature. Some series reported that there was no difference in infection rate amongst initial and redo procedures14. However, especially surgery involving CSF diversion, re-do rates are associated with increased infection as reported by Odio et al15. In our study, the one patient with post-operative infection and fever after 48 hours of surgery (positive CSF, blood culture and swab culture) was a re-do surgery for spinal dysraphism(Table 1). The culture grew Streptococcus spp, which was sensitive to Ceftriaxone. Post-operative stay was increased by 14 days and antibiotic regime extended by 14 days. After the completion of antibiotic regime, the patient recovered, incision healed well and discharged without any new neurological deficit.
Various studies report the most common organisms in surgical site infections of neurosurgery procedures are the coagulase-negative staphylococci spp16. The occurrence of Staphylococcus epidermidis and Staphylococcus aureus varies from 62-90%7. Infections due to gram negative bacteria are less common, but essential, because mortality is very high at 40-90%7. As reported by Choux et al13, simple and effective strategies of strict adherence to sterile techniques and rigorous operation theatre protocols enabled to obtain near-complete prevention of post-operative infections. With this protocol, the need for antibiotics can be reduced to minimum 6. With these simple steps, world standard infection control rates can be obtained in all centres. Re-do surgery carries higher post-op infections especially CSF diversion procedures as endorsed by other studies17.
Prevention of post-op infections in Neurosurgery is of prime importance in reducing morbidity and mortality3. A near total eradication of post-op infection does need extensive and elaborate structured protocols with or without antibiotics6. Re-do surgeries and especially CSF diversion procedures and post-op CSF leak needs more vigilance as they are associated with increased rate of infection17. Simple and effective aseptic protocols, and theatre etiquette combined with adequate antibiotic prophylaxis can achieve near zero post-op infection rate18