A surgical site infection (SSI) is defined as a wound infection that occurs following an invasive surgical procedure. Despite several advances made in surgical care over the past decades, patients undergoing abdominal surgeries continued for about one fourth of all postoperative surgical complications, with surgical site infections (SSI) are most predominant complications. One out of eight colon resections not only has a higher risk of adverse event compared to other procedures, but also has significantly high proportion of SSI that were otherwise avoided by available means of standard care. SSI accounts for more than 20% of all healthcare associated infections in postoperative period, and it has been estimated that more than one third of post operated deaths across the globe are related to SSI.Early diagnosis and management of the SSI is of paramount importance to prevent the postoperative surgical complications. Several biochemical markers have been used for early prediction of infections i.e. procalcitonin (PCT), C-reactive protein (CRP) and white blood cell (WBC). PCT known to be more sensitive and specific for the early prediction of infection and sepsis. However, the response of PCT in postoperative period especially in early diagnosis of SSI in contaminated types of bowel surgeries has not being studied yet. We believe that PCT is a reliable biochemical marker for early diagnosis of SSI.Management of SSI includes multimodal approaches, and interventions at preoperative, intraoperative and postoperative period. Several intraoperative strategies has been used to prevent the postoperative SSI, including preoperative bowel preparation, preoperative showering, used of antiseptic solutions, and bundle interventions which includes combination of all, however, none has been known to be a gold standard. Preoperative oral antibiotics (ABX) with mechanical bowel preparation (MBP) has been topic of debate for decades, and continues to be an area of profound misunderstanding of what the evidence tells us, and question remains about the futility of the intervention, we believe that preoperative oral antibiotics has a major role in prevention of postoperative SSI in contaminated types of bowel surgeries.Therefore, we undertook the study (1) diagnosis of SSI using PCT as a diagnostic tool, (2) pitfalls in the serum PCT level. (3) Preoperative oral antibiotics for prevention of SSI in contaminated types of bowel surgeries.PartⅠ PCT as a diagnostic maker of SSIBackground:Contaminated colorectal surgeries are associated with marked postoperative elevated level of biochemical markers (Procalcitonin, C-reactive protein) and this response shows similarity to those seen in sepsis which makes diagnosis difficult in the postoperative period.Methods:140 patients who underwent elective bowel surgery. Patients were divided into three groups (clean contaminated, contaminated, and dirty) types of surgeries. Procalcitonin, C-reactive protein and White blood cell count were measured at preoperative, postoperative day 1,3,5,7th day and every third day thereafter until hospital discharge or any other outcome.Results:A total of 140 patients were included for final analysis. The most common postoperative infectious complications were:Superficial SSI (n=20), deep SSI (n=5), and (intra-abdominal septic complications) (n=6). Early post-operative elevated Procalcitonin were proportional to the level of contamination on postoperative day 1-7, clean contaminated versus dirty ones (P=<0.01). Procalcitonin had better predictability than CRP for intra-abdominal septic complication on post-operative day 5 (AUC) of procalcitonin 0.89 and 0.79 respectively. A significant differences were achieved compared with the baseline level for postoperative C-reactive protein values in patients with and without incisional surgical site infection (P=0.002, P=0.015), however procalcitonin level were statistically non-significant (P=0.96, P=0.60).Conclusion:PCT is a good biochemical parameter for early prediction of deep SSI or IASCs, however, early post-operative elevated level of procalcitonin was proportional to the level of contamination. Serial monitoring of these biomarkers should be done in contaminated types of bowl surgeries to avoid unnecessary intervention.Part II Pitfalls in the measurement of serum PCTBackground:Several studies have claimed that procalcitonin (PCT) levels fluctuates according to the glomerular filtration rates (GFR), however, such changes in C-reactive protein (CRP) levels were not seen.Methods:This was a cross sectional study conducted from April 2013 to August 2015, a total of 740 patients who had PCT and CRP measured simultaneously during the first medical consultation were included. Patients were divided into infection and non-infection groups according to their GFR level. Pearson correlation were used to see the correlation between GFR and biomarkers, and the receiver operating characteristic (ROC) and under the curve (AUC) were measured.Results:PCT levels were inversely related to the GFR while CRP did not shown this correlation in patients with renal dysfunction in both types of patients with and without infection. In patients with renal dysfunction the AUC of PCT was 0.71 (95% CI:0.66-0.77) and CRP was 0.83 (95% CI:0.78-0.87) respectively. Pearson correlation revealed; in patients with infection the values of PCT (p=0.001), (r=0.-48) and CRP (p=0.93), (r=0.06) and in patients without infections the values of PCT (p=0.01), (r=0.-32), and CRP (p=0.24), (r=0.-07) respectively. CRP level varies according to the severity of the infection while PCT level were higher in more severe types of infections, sepsis and septic shock.Conclusion:PCT increases in parallel to the deterioration of renal function and shows inverse relation with the GFR, rendering this biomarker reliable in renal dysfunction. CRP level varies according to the severity of the infection while PCT level were higher in sepsis and septic shock patients.Part III Prevention of SSIBackground:Preoperative bowel preparation with or without oral antibiotics is a controversial issue for the outcome of postoperative SSI. We evaluated the efficacy of oral antibiotics adjunct to systemic antibiotics with mechanical bowel preparation for prevention of SSI in contaminated types of colorectal procedures.Methods:Patients undergoing abdominal surgeries with clean-contaminated contaminated and dirty wounds were included. The patients were to receive mechanical bowel preparation (MBP group) or to receive mechanical bowel preparation with oral antibiotics (MBP+ABX group).The primary outcome was the rate of SSI. The secondary outcomes included the extra abdominal complication, duration of postoperative ileus and readmission rate.Results:Study was conducted from July 15,2014 to January 20,2016,206 patients underwent colorectal surgeries and 190 patients were randomized into two groups,95 patients in MBP+ABX group, and 95 in MBP group. There were 8 SSI in MBP+ABX group and 26 in the MBP group (8.42% vs 27.3%, P= 0.004). Extra-abdominal complication were seen in 13 cases,6 in MBP+ABX group and 7 in MBP group (6.3% vs 7.3%, P=0.77). The duration of post-operative ileus between two groups were statistically non-significant, (P=0.23). There were no case of readmission in MBP+ABX group and two cases in MBP group (P=0.04). The multivariate logistic regression (adjusted) model revealed; blood loss≥500 mL (OR:3.54; 95% CI:1.36-9.18; P=0.009), ASA score≥3 (OR:5.10; 95%CI 2.14-12.1; P=0.001), and administration of preoperative oral ABX (OR:0.35; 95%CI 0.15-0.80; P=0.01) independently affected the incidence of SSI.Conclusion:Preoperative oral ABX adjunct to systemic antibiotics and MBP significantly reduces SSI, and minimize the readmission rates in contaminated types of colorectal surgery.