Prophylaxis antibiotics in colorectal surgery By: Hanaa Tashkandi

introduction *25 % of all nosocomial infections are wound infections and their costs are greater than one billion dollar per year in the United states.

No (gold standard) regimen can be identified. *contamination by bacteria from the content of the large bowel means that colorectal surgery is associated with a particularly high risk of surgical wound infection.

*If antimicrobial prophylaxis is not used,about 40% of patients will develop wound infection after colorectal surgery. *This figure is reduced to around 11% when patients receive some form of antimicrobial prophylaxis.

* In colorectal surgery,the prophylactic regimen should include broad spectrum cover for both aerobic and anaerobic organisms. *To prevent post operative infections, it is crucial that the concentration of antibiotics in the tissue surrounding the surgical wound is sufficient at the time of bacterial contamination.

A recent study done on the use of prophylactic antibiotics orally in colorectal surgery. (department of surgery hospital valle de hebron.University of Barcelona) -300 consequative colorectal resections were studied and all the patients received mechanical bowel preparation with intravenous antibiotics.

-the intravenous antibiotics in the study was (cefoxitin)..one pre operative at the time of skin incision..two post operative doses.

*three groups: -1-three doses of (neomycin & metronidazole) -2-one oral dose. -3-no oral dose.

Conclusion of this study Addition of oral antibiotic in all patient prophylaxis is associated with lower patient tolerance in terms of increase nausea, vomiting and abdominal pain with no advantages in preventing of post operative complications. *so the recommendation was not to give oral antibiotics Int. J colorectal disease.2005 Nov 20(6):542-6

A more recent survey of United Kingdom antibiotic policies demonstrated a similar pattern with Cefuroxime plus Metronidazol. -this combination is the most frequently recommended policy.

-the BNF currently recommends either : *a single dose of Gentamycin plus metronidazole. or *Cefuroxime plus Metronidazole given in two hours prior to surgery.

Timing of antibiotics prophylaxis Current recommendations are that the parental antibiotics used in prophylaxis should be given in sufficient dosage within 30 minutes preceding incision. (this is also depend on the half life of the antibiotics and the pharmacokinetics)

Factors associated with an increased risk of surgical wound infection colorectal surgery *duration of the operation. *obesity. *presence of drains. *left sided colonic resection. * inflammatory bowel disease. * preoperative blood transfusion was also found to be associated with an increased risk of surgical wound infection in two trials.

** A study regarding the comparison of the prophylactic efficacy of Ceftriaxone and Ceferuxime in colorectal surgry. (John c woodfield, andre M van rij, Ross a pettigew, dome Bott)

y * prospective, randomized,double blind study of 1013 patients undergoing abdominal surgery, *the prophylactic use of Ceftriaxone and Cefotaxime were compared.

The result: both antibiotics provide comparable wound prophylaxis as long as metronidazole is added for colorectal and appendeceal surgery.

Ceftriaxone is having an additional apparent benefits of reducing other post operative infections, being less depandant on metronidazole as an adjuvant and providing a more effective prophylactic cover against staphylococcus aureus.

((2000 J chemother)) A multicenter randomized trial of prophylaxis with intravenous -cefepine + metronidazole. Or -ceftriaxone + metronidazole. In colorectal surgery.

The two prophylactic antimicrobial regimens in 615 patients undergoing elective colorectal surgical procedures. -patients ranged in age from 19 – 92 years (median 66 year ).

All patients underwent mechanical bowel preparation. -patients were randomized to receive preoperative infusions of 2 grams cefepime or 2 grams ceftriaxone, followed by 500 mg metronidazole. -patients were followed for up to 6 weeks after surgery.

-antimicrobial prophylaxis was successful in preventing primary site infection 92.8% of patients in the cefepine + metronidazole group. And 92.9 % of patients in the ceftriaxone + metronidazole group.

ha So A single dose of cefepime + metronidazole Seems to be a very useful alternative to other regimens for prophylaxis in patients undergoing colorectal surgery.

h There was another American study, its goal was based on if single dose prophylaxis given just before the start of surgery is as effective as multiple doses in preventing surgical wound infection and is also associated with less toxicity,fewer adverse events and lower costs.

This study involved 414 patients. -one group had no post surgical prophylaxis. -one group had antibiotics continued for up to 24 hours -one group had antibiotics usage for up to 48 hours. -one group had antibiotics usage exceed 48 hours after surgery.

and there was essentially no change.

(song and glenny performe an extensive systemic review and meta-analysis on colorectal antibiotics prophylaxis. -their analysis of 147 randomized clinical trials concluded that :

Single dose antibiotic regimens were effective preventing surgical wound infection except for the possible inadequacy of the antibiotics, example : Doxycycline, pipracillin, or metronidazole used alone.

The meta analysis demonstrated that single dose regimen were as effective as regimens with post operative doses and \ or multiple drug regimens.