**1.5 Using microbiome science to develop bowel preparation**

Bowel preparation relies on the traditional paradigm [107, 108]. Still, there is a lack of recognition of the importance of normal microbiota in suppressing colonization resistance and promoting intestinal healing. The microbiota includes bacteria, viruses, fungi, and protozoans, which live symbiotically with humans. Gut microbiota (GM) are of two types. According to their location, they are named mucosal-associated microbiota (MAM) and luminal microbiota (LM). Bacteroidetes and Proteobacteria are representative of MAM, whereas Firmicutes and Actinobacteria are representative of the LM [109]. MAM stimulates the mucus secretion in the gut. It also produces short-chain fatty acids, acetate, butyrate, and propionate. These are the mediators of the host immune system. The LM, mainly Firmicutes, produces butyrate, which enhances intestinal barrier function and has anti-inflammatory and anticancer activity [110]. Studies lack how normal microbiota are reintroduced after surgery and provide health-promoting effects [111]. In the era of laparoscopic surgery, oral antibiotics may be less critical as the microbiota are minimally disturbed [94]. The intestinal decontamination, as complete as possible, should be the goal of adequate bowel preparation [112]. In current practice, by doing broad-based bowel preparation, decontamination of diverse GM happens. Diverse GM suppresses the development of potential harmful pathobionts and promotes intestinal healing. The next generation of bowel preparation using microbial metagenomics focuses on selective gut decontamination. Gentle bowel cleansing can begin with nutritional supplements and non-microbicidal

#### *Bowel Preparation before Elective Colorectal Surgery: Its Current Role DOI: http://dx.doi.org/10.5772/intechopen.107093*

anti-virulence agents. Here the nutritional supplement includes the nutrients known to suppress bacterial virulence without affecting their growth. Hence the normal GM proliferates but the virulence of pathogenic microbiota is suppressed [113]. Therefore, a balanced solution containing both nutrients and anti-virulence agents will be the next generation and more scientifically validated approach for bowel preparation before colorectal surgery that allows for targeted cleansing while preserving the vital function of the normal microbiota. However, evidence favored the MBP with POA before elective colorectal surgery. Now the time has come to allow the next-generation microbial science technology to recalibrate the traditional bowel preparation.

#### **1.6 Bowel preparation and surgical recovery**

The surgical recovery mainly focuses on the protective benefit of bowel preparation against SSI and anastomotic leak (AL), which in turn leads to increased intraabdominal collections, reoperation rate, length of hospital stays (LOS), and 30 days' morbidity. Following colorectal surgery, about 20% of patients may suffer from SSI [114]. SSIs are associated with increased morbidity and LOS and delayed recovery. A number of high-quality studies report a reduction in SSI rates after MBP and POA [8, 70, 76, 115]. Klinger et al. analyzed subjects from the American College of Surgeons–National Surgical Quality Improvement Program (ACS-NSQIP) database and observed its protective benefit against SSI and AL rates [4, 17]. ACS-NSQIP data analysis also demonstrated a significant reduction in the readmission rate and LOS in a patient with MBP plus POA [28]. Interestingly, also it has been observed that AL following elective surgery for colorectal cancer adversely affects overall survival. It is probably because of increased local cancer recurrence as well as delays in starting the chemotherapy. Although the risk of AL is 2.2 times higher with only MBP, it decreases with the addition of POA [116], probably because the addition of POA reduces bowel bacterial colonization, which might lead to a decrease in infectious complications. Similar observations on recovery from laparoscopic colorectal surgery indicate that the LOS, complication rate, and reoperation rate decrease after the use of MBP and POA.

The protocol of enhanced recovery after surgery (ERAS) is established on the principle of reduction in surgically induced physiological and metabolic stress. The benefit of MBP plus POA can be a pillar in the ERAS pathway. ERAS society also recommends using preoperative MBP plus POA before elective colorectal surgery [28] because it reduces postoperative ileus [117], non-SSI-related complications [76], the LOS, and hospital readmission rates [118]. The ACS-NSQIP data indicate a reduction in 30-day mortality with MBP plus POA than not having bowel preparation at all, which is likely due to an overall decrease in septic complications [76]. These data suggest that bowel preparation (MBP plus POA) has a significant advantage on surgical recovery by reducing the SSIs, anastomotic leak, postoperative ileus, reoperation, and readmission rate as well as LOS and 30-day mortality.
