Br. J. Surg. Vol. 63 (1976) 969-972
An elemental diet as preoperative preparation of the colon J . F. G U R R Y A N D R . B . E L L I S - P E G L E R * SUMMARY
In a study comparing patients prepared for colonic surgery with an elemental diet (Vivonex) with a control group there was no significant difference in incidence of wound infection or other complications between groups. Furthermore, there was no change in the population levels of the colonic microflora nor were the numbers of species decreased after 2-4 days on the diet. Although in most cases aiding in the mechanical preparation of the colon, the elemental diet has not been shown to confer any other advantage. THE best method of preparing the colon for surgery remains unresolved. It is agreed that the reduction of the faecal colonic mass preoperatively and the avoidance of peritoneal soilage during operation result in a decreased incidence of complications (Nichols and Condon, 1971; Rosenberg et al., 1971; Herter, 1972). However, the use of preoperative oral antibacterial regimes is controversial, although some regimes significantly alter the faecal flora (Nichols et al., 1972). The clinical relevance of this is uncertain, but a recent prospective study shows the efficacy of oral neomycin/tetracycline used for 48 hours preoperatively (Washington et al., 1974). The occasional selective overgrowth of bacteria leading to enterocolitis and the enhancement of drug-resistant organisms in a hospital community are nevertheless generally regarded as complications arising from this form of preparation. Further, experimental and clinical evidence indicates that suture line recurrence of tumour is more common when antibiotics are used to prepare the bowel for surgery (Vink, 1954; Herter and Slanetz, 1968). Winitz et al. in 1965 first suggested using a minimal residue diet as a preoperative bowel preparation; as the bulk of this diet is presumably absorbed before entering the colon, the faecal mass is markedly reduced. I n 1970 Winitz et al. showed changes in the faecal flora in 8 subjects fed a glucose-based elemental diet for 4 days and given an enema after 24 hours of the diet. A marked reduction in the faecal microbial population occurred and there was simplification of the flora to essentially three groups : bacteroides, coliforms and enterococci. The present investigation has been undertaken to study the effects of such a diet in association with the administration of an enema on the preparation of the bowel for surgery, the postoperative sepsis rate and the faecal microbial populations. Patients and methods Vivonex (Eaton Laboratories) is a commercial preparation containing 300 kcal per packet and is a
water-soluble powder. Each patient received 6 packets per day which supplies 5.88 g of available nitrogen (in the form of pure amino acids), 2.61 g fat (principally triglyceride of linoleic acid) and 407.4 g carbohydrate (glucose only). Vitamins and electrolytes are included. Patients were willing to take Vivonex in all cases, but generally complained of the taste; acceptability improved later in the study when commercial fruit drink in powder form was used as flavouring. Patients for elective colonic surgery were allocated randomly into three groups; patients with clinical evidence of obstruction were excluded. All the patients were in hospital for 5 days preoperatively, receiving an enema 24 hours after admission and were fasted for 12 hours before operation. Group 1 patients were treated as controls and had a normal ward diet during their preoperative hospital stay; group 2 patients had a normal ward diet for 2 days and Vivonex for the next 2 days; group 3 patients received Vivonex for 4 days. The presence of pus constituted the evidence of wound infection, as did the drainage of faecal material from an anastomotic leak. The quality of bowel preparation in terms of faecal content was assessed by the surgeon at operation, in ignorance of the group to which the patient belonged. From the first 8, 7 and 9 patients from groups 1, 2 and 3 respectively, a sample of the first stool passed in hospital was cultured, as was a specimen of bowel content taken from the resected specimen at surgery. Colonic contents were cultured within 15 minutes of removal from the gut, while solid faeces were cultured within 24 hours of being passed, as described elsewhere (Ellis-Pegler et al., 1975). Bacterial groups identified were enterobacteria, staphylococci, streptococci, bacilli, lactobacilli, yeasts, bifidobacteria, bacteroides, clostridia and veilIonellae. Colonies were counted and the concentrations of organisms expressed as log,, organisms/g of specimen (wet weight). The lower limit for the detection of bacteria by this method is lo2organisms/g. Results 1. Clinical Altogether 24, 7 and 20 patients were included in groups 1 , 2 and 3 respectively. After a total of 20 cases had been admitted to the trial, assessment showed that the regime of 2 days of Vivonex was not providing
* Department of Surgery and Communicable Disease Unit, St George’s Hospital, London. Present addresses: J. F. Gurry, Department of Surgery, Toronto Western Hospital, Canada. R. B. Ellis-Pegler, Clinical Microbiologist, Auckland Hospital, New Zealand. 969
J. F. Gurry and R. B. Ellis-Pegler Table I: CLINICAL RESULTS Group 1 No. Number of patients Acceptable bowel preparation Incidence of wound infection Incidence of anastomotic leakage Mortality Duration of postoperative ileus (d) Mean Range Postoperative hospital siay (d) Mean Range
%,
Group 2
Group 3
No. 7 2
28
No. 20 16
80
%,
%
24 6
25
11
45.8
3
43
10
50
3
12.5
1
14
3
15
2
8.3
1
14
2
10
3.6 2-6
4.2 3-5
14.2 a-22
13.1 9-1 7
4.3 2-7
:;:d
acceptable mechanical bowel preparation ; no further patients were therefore admitted to group 2. The groups were comparable as regards age, sex and the primary procedure needing surgery. Eleven patients had colonic Crohn’s disease, 2 had diverticular disease and the remaining 38 had carcinoma of colon or rectum. Eleven right hemicolectornies, 3 transverse colectomies, 6 left hemicolectomies, 15 sigmoid colectomies, 14 anterior resections and 2 total colectomies were performed. The clinical results are shown in Table I. N o significant differences between the groups were apparent, except for the effectiveness of 4 days’ Vivonex and an enema on the preparation of the bowel. The overall mortality of 9.8 per cent probably reflects the age of the patients. Excluding the 11
patients with Crohn’s disease (no mortality in this group), 60 per cent were over 70 and 15 per cent were over 80 years. Two deaths, one from each of groups 1 and 2, were directly attributable t o surgery as both died of sepsis associated with anastomotic dehiscence; both were over 80 years. Postoperative myocardial infarction in 2 patients and respiratory failure in onc were responsible for the remaining deaths who were all patients over 70. Seven patients had an anastomotic leak; 2 were over 80 years and are those recorded as dying of sepsis. Two patients with Crohn’s colitis had a transient leak, and 3 patients after low anterior resection develoDed minor dehiscence of their anastomosis. Although ‘adequate bowel preparation’ is widely accepted as desirable, the incidence of wound infection in those described as achieving this was not significantly different from in the remainder: 11 out of 24 (45.7 per cent) and 13 out of 27 (48 per cent) respectively . 2. Microbiological The results of the microbiological study are tabulated in Table 11. Although the number of patients studied was small, there were n o significant differences between the median concentrations of any bacterial group (or of total aerobic or anaerobic organisms) on admission and at operation in each of the three groups. In the faecal specimens cultured o n admission from the 24 patients, bifidobacteria were present in lower concentrations than in a normal but younger population drawn from the same environment; for all other bacterial groups the concentrations of organisms were similar to normal (Ellis-Pegler et al., 1975).
Table 11: RESULTS OF MICROBIOLOGICAL STUDY Grouo 1 Bacterial moue Enterobacteria Staphylococci Streptococci Bacilli Lactobacilli Yeasts Total aerobes Bifidobacteria Bacteroides Clostridia Veillonellae Total anaerobes
Preoo. 7.6 (n-9.0) 3.2 (2,043) 7.5 (6.6-8.1) 2.2 (n-3.4) 4.7 (n-5.9) X (n-4.2) 8.3 (7.0-9.0) 6.6 (n-9.3)
00.
7.5 (n-9.4) 3.6 (n-4.0) 7.0 (648.6) 2.4 (n-3.6) 4.4 (n-5.9) X (n-4.7)
GrouD 3
GrouD 2
Preop. 8.2 (7.0-9.1) 4.1 (n-4.9) 7.0 (6.7-8.4) 3.1 (2.3-3.9) 4.8 (n-6.5) 3.1 fn-3.7)
OP. 8.3 (7.7-9.0) 3.0 (n-5.9) 8.1 (5’5-8.2)
2.7 (11-3.5) 4.8 (3.3-6.2) X (n-4.2)
(9.4-10.3) 8.4 (7.6-9.5) 4.8 (n-7.6)
7.9 (7.0-9.5) 6.0 (n-8.2) 9.7 (8.0-1 0.3) 7.4 (n-9.2) 4.3 (n-6.7)
8.3 (7.1 1-9.1) 7.2 (n-9.5) 9.4 (8.2-10.2) 7.5 (5.3-8.4) (n4.9)
(6.8-9.4) 6.1 (n-8.3) 9.3 (8.5-10.3) 8.3 (7.6-9.1) X (n-5.0)
10.1 (94-10.3)
9.8 (8.1-1 0.5)
9.5 (8.2-10.2)
9.3 (8.7-10.3)
10.1
x
8.5
Preop. 7.7 (6.1-8‘7) 3.8 (2.0-5.8) 7.7 (11-9.6) 2.3 (n-2.8) 4.4 (n-6.3) X (n-4.7)
OP. 7.7 (6.0-9.0) 2.7 (11-5.6) 6.9 (n-7.6) X (n-3.0) 4.0 (2.0-5.3) 3.0 fn-5.4)
7.9 (7.4-9.2) 7.2 (n-9.5) 9.7 (9.1-10.4) 7.3 (n-9.3) X (11-6.6)
7.8 (6.0-9.0) 8.1 (n-9.4) 9.0 (3.2-1 0.I ) 8.1 (n-8.6) X (11-6.5)
9.8 (9.1-10.4)
9.3 (3.3-10.4)
Results given as the median concentration with the range in parentheses; all concentrations expressed as log,, organisrns/g of specimen (wet weight). n, Not detected; X, median value not determinable.
970
Elemental diet as preoperative colon preparation Discussion We have confirmed the findings of others (Winitz et al., 1966; Glotzer et al., 1973) that Vivonex for several days results in a large bowel relatively free of faeces. All 4 patients with inadequate preparation after 4 days of Vivonex had a tightly stenosing carcinoma which may have contributed to this finding. In contrast, 2 days of Vivonex clearly does not provide adequate preparation. In a clinical study Johnson (1974) compared preoperative Vivonex with preoperative antibiotics, neomycin and phthalylsulphathiazole and mechanical cleansing and found no difference in the incidence of wound infection (33 per cent overall). Cooney et al. (t974), in a n experimental study on rats undergoing colonic surgery, found elemental diets as effective in decreasing postoperative sepsis as the oral antibiotics neomycin and lincomycin, but no more so than mechanical preparation alone. In addition, these elemental diets did not prevent anastomotic leakage. Our study agrees with these findings in that we found no benefit from Vivonex in reduction of wound infection, duration of ileus or hospital stay, although the last is a very crude indication of the complication rate. Mortality and anastomotic leakage were too infrequent for this study to assess. The rate of wound infection was high at 47 per cent, comparing unfavourably with reported rates of 5 per cent (Nichols and Condon, 1971) and 30 per cent (Herter, 1972), although similar to those reported by Hughes (1967), Everett et al. (1969) and Burton (1973). Four days of Vivonex with an enema, and indeed the enema alone, are inadequate preparation for colonic surgery if wound infection is the determinant of efficacy. Like other workers (Attebery et al., 1972; Crowther et al., 1973; Glotzer et al., 1973; Bounous and Devroede, 1974), we failed to confirm the impressive reductions in bacterial concentrations described by Winitz et al. (1970) with an elemental diet. However, smaller reductions in ‘extremely oxygen-sensitive anaerobes’ and enterococci and minor increases in enterobacteria have been recorded. Alterations in faecal neutral steroids while on Vivonex have also been ascribed to possible changes in microbial flora undetected by present culturing techniques (Crowther et al., 1973). We did not speciate enterococci and changes in this group could have gone undetected. A comparison of preoperative faecal specimens and operative colonic specimens assumes that the colonic is the same as the faecal flora. Although they may not be identical (Hawksworth et al., 1971; Nichols et al., 1971), the differences are not great. Our concern was whether an elemental diet induced important changes in the flora of the large bowel at the site of operation-the site of potential peritoneal contamination-and it does not do this. It would be possible to use this diet with more vigorous mechanical preparation and a short course of oral or perioperative antibacterial agents. A multifaceted approach such as this might result in the
most effectively prepared patients with the lowest infection rate postoperatively.
Acknowledgements We wish to thank Eaton Laboratories for providing Vivonex, Mrs C. Crabtree for technical microbiological assistance and Mr R. F. Galbraith, University of London, for assistance with statistical interpretation. R. B. Ellis-Pegler was the recipient of a research grant from the Wellcome Trust. References and FINEGOLD S. M. (1972) Effect of a partially chemically defined diet on normal faecal flora. Am. J. Cfin. Nutr. 25, 1391-1398. BOUNOUS G . and DEVROEDE G . J . (1974) Effects of an elemental diet on human faxal flora. Gastroenterology 662, 210-214. BURTON R. c . (1973) Postoperative wound infection in colonic and rectal surgery. Br. J. Surg. 60, 363365. COONEY D . R., WASSNER J. D . , GROSFELD J. L. et d. (1974) Are elemental diets useful in bowel preparation? Arch. Surg. 109, 206-210. CROWTHER J. s., DRASAR B. s., GODDARD P. et al. (1973) The effect of a chemically defined diet on the faecal flora and faecal steroid concentration. Gut 14, 790-793. ELLIS-PEGLER R. B., CRABTREE c. and LAMBERT H. P. (1975) The faecal flora of children in the United Kingdom. J . Hyg. (Camb.) 75, 135-142. EVERETT M. T., BROGAN J . D. and NETTLETON J. (1969) The place of antibiotics in colonic surgery: a clinical study. Br. J. Surg. 56, 679-684. GLOTZER D. J., BOYLE P. L. and SILEN w . s. (1973) Preoperative preparation of the colon with an elemental diet. Surgery 745, 703-707. HAWKSWORTH G . , DRASAR B. s. and HILL M. J. (1971) Intestinal bacteria and the hydrolysis of glycosidic bonds, J . Med. Microbiol. 4,451459. HERTER F. P. (1972) Preparation of the bowel for surgery. Surg. Clin. North Am. 52, 859-870. HERTER F. P. and SLANETZ c. A . (1968) Preoperative intestinal preparation in relation to subsequent development of cancer at the suture line. Surg. Gynecol. Obstet. 127, 49-56. HUGHES E. s. R. (1967) Asepsis in large bowel surgery. Med. J . Aust. 2, 663-686, JOHNSON w . c . (1974) Oral elemental diet: a new bowel preparation. Arch. Surg. 108, 32-34. NICHOLS R. L. and CONDON R. E. (1971) Preoperative preparation of the colon. Surg. Gynecol. Obstet. 132, 323-337. NICHOLS R. L., CONDON R . E., GORBACH s. L. et al. (1972) Efficacy of preoperative antimicrobial preparation of the bowel. Ann. Surg. 176, 227-232. NICHOLS R. L., GORBACH s. L. and CONDON R. E. (1971) Alteration of intestinal microflora following preoperative mechanical preparation of the colon. Dis. Colon Rectum 14. 123-127. ATTEBERY H. R., SUTTER V. L.
971
J. F. Gurry and R. B. Ellis-Pegler et al. (1971) Preparation of the intestine in patients undergoing major large bowel surgery, mainly for neoplasms of the colon and rectum. Rr. J. Surg. 58, 266-269. VINK M. (1954) Local recurrence of cancer in the large bowel : the role of implantation metastases and bowel disinfection. BY.J. Suvg. 41, 431-433. WASHINGTON J. A., DEARING w. H., JUDD E. s. et al. (1974) Effect of preoperative antibiotic regimen on development of infection after intestinal surgery: prospective, randomized, double-blind study. Ann. Surg. 180, 567-572.
ROSENBERG I. L., GRAHAM N. G., DE DOMBAL F. T.
972
et al. (1966) Regulation of intestinal flora patterns with chemical diets. Fed. Proc. 25, 343. WINITZ M., ADAMS R. F., SEEDMAN D. A. et al (1970) Studies in metabolic nutrition employing chemically defined diets: 11. Effect on gut microflora populations. Am. J. Clin. Nutr. 23, 546-559. WINITZ M., GRAFF J., GALLAGHER N. et al. (1965) Evaluation of chemical diets as nutrition for man-in-space. Nature (Lond.) 205, 741-743, WINITZ M., ADAMS R . F., SEEDMAN D. A.
An elemental diet as preoperative preparation of the colon J . F. G U R R Y A N D R . B . E L L I S - P E G L E R * SUMMARY
In a study comparing patients prepared for colonic surgery with an elemental diet (Vivonex) with a control group there was no significant difference in incidence of wound infection or other complications between groups. Furthermore, there was no change in the population levels of the colonic microflora nor were the numbers of species decreased after 2-4 days on the diet. Although in most cases aiding in the mechanical preparation of the colon, the elemental diet has not been shown to confer any other advantage. THE best method of preparing the colon for surgery remains unresolved. It is agreed that the reduction of the faecal colonic mass preoperatively and the avoidance of peritoneal soilage during operation result in a decreased incidence of complications (Nichols and Condon, 1971; Rosenberg et al., 1971; Herter, 1972). However, the use of preoperative oral antibacterial regimes is controversial, although some regimes significantly alter the faecal flora (Nichols et al., 1972). The clinical relevance of this is uncertain, but a recent prospective study shows the efficacy of oral neomycin/tetracycline used for 48 hours preoperatively (Washington et al., 1974). The occasional selective overgrowth of bacteria leading to enterocolitis and the enhancement of drug-resistant organisms in a hospital community are nevertheless generally regarded as complications arising from this form of preparation. Further, experimental and clinical evidence indicates that suture line recurrence of tumour is more common when antibiotics are used to prepare the bowel for surgery (Vink, 1954; Herter and Slanetz, 1968). Winitz et al. in 1965 first suggested using a minimal residue diet as a preoperative bowel preparation; as the bulk of this diet is presumably absorbed before entering the colon, the faecal mass is markedly reduced. I n 1970 Winitz et al. showed changes in the faecal flora in 8 subjects fed a glucose-based elemental diet for 4 days and given an enema after 24 hours of the diet. A marked reduction in the faecal microbial population occurred and there was simplification of the flora to essentially three groups : bacteroides, coliforms and enterococci. The present investigation has been undertaken to study the effects of such a diet in association with the administration of an enema on the preparation of the bowel for surgery, the postoperative sepsis rate and the faecal microbial populations. Patients and methods Vivonex (Eaton Laboratories) is a commercial preparation containing 300 kcal per packet and is a
water-soluble powder. Each patient received 6 packets per day which supplies 5.88 g of available nitrogen (in the form of pure amino acids), 2.61 g fat (principally triglyceride of linoleic acid) and 407.4 g carbohydrate (glucose only). Vitamins and electrolytes are included. Patients were willing to take Vivonex in all cases, but generally complained of the taste; acceptability improved later in the study when commercial fruit drink in powder form was used as flavouring. Patients for elective colonic surgery were allocated randomly into three groups; patients with clinical evidence of obstruction were excluded. All the patients were in hospital for 5 days preoperatively, receiving an enema 24 hours after admission and were fasted for 12 hours before operation. Group 1 patients were treated as controls and had a normal ward diet during their preoperative hospital stay; group 2 patients had a normal ward diet for 2 days and Vivonex for the next 2 days; group 3 patients received Vivonex for 4 days. The presence of pus constituted the evidence of wound infection, as did the drainage of faecal material from an anastomotic leak. The quality of bowel preparation in terms of faecal content was assessed by the surgeon at operation, in ignorance of the group to which the patient belonged. From the first 8, 7 and 9 patients from groups 1, 2 and 3 respectively, a sample of the first stool passed in hospital was cultured, as was a specimen of bowel content taken from the resected specimen at surgery. Colonic contents were cultured within 15 minutes of removal from the gut, while solid faeces were cultured within 24 hours of being passed, as described elsewhere (Ellis-Pegler et al., 1975). Bacterial groups identified were enterobacteria, staphylococci, streptococci, bacilli, lactobacilli, yeasts, bifidobacteria, bacteroides, clostridia and veilIonellae. Colonies were counted and the concentrations of organisms expressed as log,, organisms/g of specimen (wet weight). The lower limit for the detection of bacteria by this method is lo2organisms/g. Results 1. Clinical Altogether 24, 7 and 20 patients were included in groups 1 , 2 and 3 respectively. After a total of 20 cases had been admitted to the trial, assessment showed that the regime of 2 days of Vivonex was not providing
* Department of Surgery and Communicable Disease Unit, St George’s Hospital, London. Present addresses: J. F. Gurry, Department of Surgery, Toronto Western Hospital, Canada. R. B. Ellis-Pegler, Clinical Microbiologist, Auckland Hospital, New Zealand. 969
J. F. Gurry and R. B. Ellis-Pegler Table I: CLINICAL RESULTS Group 1 No. Number of patients Acceptable bowel preparation Incidence of wound infection Incidence of anastomotic leakage Mortality Duration of postoperative ileus (d) Mean Range Postoperative hospital siay (d) Mean Range
%,
Group 2
Group 3
No. 7 2
28
No. 20 16
80
%,
%
24 6
25
11
45.8
3
43
10
50
3
12.5
1
14
3
15
2
8.3
1
14
2
10
3.6 2-6
4.2 3-5
14.2 a-22
13.1 9-1 7
4.3 2-7
:;:d
acceptable mechanical bowel preparation ; no further patients were therefore admitted to group 2. The groups were comparable as regards age, sex and the primary procedure needing surgery. Eleven patients had colonic Crohn’s disease, 2 had diverticular disease and the remaining 38 had carcinoma of colon or rectum. Eleven right hemicolectornies, 3 transverse colectomies, 6 left hemicolectomies, 15 sigmoid colectomies, 14 anterior resections and 2 total colectomies were performed. The clinical results are shown in Table I. N o significant differences between the groups were apparent, except for the effectiveness of 4 days’ Vivonex and an enema on the preparation of the bowel. The overall mortality of 9.8 per cent probably reflects the age of the patients. Excluding the 11
patients with Crohn’s disease (no mortality in this group), 60 per cent were over 70 and 15 per cent were over 80 years. Two deaths, one from each of groups 1 and 2, were directly attributable t o surgery as both died of sepsis associated with anastomotic dehiscence; both were over 80 years. Postoperative myocardial infarction in 2 patients and respiratory failure in onc were responsible for the remaining deaths who were all patients over 70. Seven patients had an anastomotic leak; 2 were over 80 years and are those recorded as dying of sepsis. Two patients with Crohn’s colitis had a transient leak, and 3 patients after low anterior resection develoDed minor dehiscence of their anastomosis. Although ‘adequate bowel preparation’ is widely accepted as desirable, the incidence of wound infection in those described as achieving this was not significantly different from in the remainder: 11 out of 24 (45.7 per cent) and 13 out of 27 (48 per cent) respectively . 2. Microbiological The results of the microbiological study are tabulated in Table 11. Although the number of patients studied was small, there were n o significant differences between the median concentrations of any bacterial group (or of total aerobic or anaerobic organisms) on admission and at operation in each of the three groups. In the faecal specimens cultured o n admission from the 24 patients, bifidobacteria were present in lower concentrations than in a normal but younger population drawn from the same environment; for all other bacterial groups the concentrations of organisms were similar to normal (Ellis-Pegler et al., 1975).
Table 11: RESULTS OF MICROBIOLOGICAL STUDY Grouo 1 Bacterial moue Enterobacteria Staphylococci Streptococci Bacilli Lactobacilli Yeasts Total aerobes Bifidobacteria Bacteroides Clostridia Veillonellae Total anaerobes
Preoo. 7.6 (n-9.0) 3.2 (2,043) 7.5 (6.6-8.1) 2.2 (n-3.4) 4.7 (n-5.9) X (n-4.2) 8.3 (7.0-9.0) 6.6 (n-9.3)
00.
7.5 (n-9.4) 3.6 (n-4.0) 7.0 (648.6) 2.4 (n-3.6) 4.4 (n-5.9) X (n-4.7)
GrouD 3
GrouD 2
Preop. 8.2 (7.0-9.1) 4.1 (n-4.9) 7.0 (6.7-8.4) 3.1 (2.3-3.9) 4.8 (n-6.5) 3.1 fn-3.7)
OP. 8.3 (7.7-9.0) 3.0 (n-5.9) 8.1 (5’5-8.2)
2.7 (11-3.5) 4.8 (3.3-6.2) X (n-4.2)
(9.4-10.3) 8.4 (7.6-9.5) 4.8 (n-7.6)
7.9 (7.0-9.5) 6.0 (n-8.2) 9.7 (8.0-1 0.3) 7.4 (n-9.2) 4.3 (n-6.7)
8.3 (7.1 1-9.1) 7.2 (n-9.5) 9.4 (8.2-10.2) 7.5 (5.3-8.4) (n4.9)
(6.8-9.4) 6.1 (n-8.3) 9.3 (8.5-10.3) 8.3 (7.6-9.1) X (n-5.0)
10.1 (94-10.3)
9.8 (8.1-1 0.5)
9.5 (8.2-10.2)
9.3 (8.7-10.3)
10.1
x
8.5
Preop. 7.7 (6.1-8‘7) 3.8 (2.0-5.8) 7.7 (11-9.6) 2.3 (n-2.8) 4.4 (n-6.3) X (n-4.7)
OP. 7.7 (6.0-9.0) 2.7 (11-5.6) 6.9 (n-7.6) X (n-3.0) 4.0 (2.0-5.3) 3.0 fn-5.4)
7.9 (7.4-9.2) 7.2 (n-9.5) 9.7 (9.1-10.4) 7.3 (n-9.3) X (11-6.6)
7.8 (6.0-9.0) 8.1 (n-9.4) 9.0 (3.2-1 0.I ) 8.1 (n-8.6) X (11-6.5)
9.8 (9.1-10.4)
9.3 (3.3-10.4)
Results given as the median concentration with the range in parentheses; all concentrations expressed as log,, organisrns/g of specimen (wet weight). n, Not detected; X, median value not determinable.
970
Elemental diet as preoperative colon preparation Discussion We have confirmed the findings of others (Winitz et al., 1966; Glotzer et al., 1973) that Vivonex for several days results in a large bowel relatively free of faeces. All 4 patients with inadequate preparation after 4 days of Vivonex had a tightly stenosing carcinoma which may have contributed to this finding. In contrast, 2 days of Vivonex clearly does not provide adequate preparation. In a clinical study Johnson (1974) compared preoperative Vivonex with preoperative antibiotics, neomycin and phthalylsulphathiazole and mechanical cleansing and found no difference in the incidence of wound infection (33 per cent overall). Cooney et al. (t974), in a n experimental study on rats undergoing colonic surgery, found elemental diets as effective in decreasing postoperative sepsis as the oral antibiotics neomycin and lincomycin, but no more so than mechanical preparation alone. In addition, these elemental diets did not prevent anastomotic leakage. Our study agrees with these findings in that we found no benefit from Vivonex in reduction of wound infection, duration of ileus or hospital stay, although the last is a very crude indication of the complication rate. Mortality and anastomotic leakage were too infrequent for this study to assess. The rate of wound infection was high at 47 per cent, comparing unfavourably with reported rates of 5 per cent (Nichols and Condon, 1971) and 30 per cent (Herter, 1972), although similar to those reported by Hughes (1967), Everett et al. (1969) and Burton (1973). Four days of Vivonex with an enema, and indeed the enema alone, are inadequate preparation for colonic surgery if wound infection is the determinant of efficacy. Like other workers (Attebery et al., 1972; Crowther et al., 1973; Glotzer et al., 1973; Bounous and Devroede, 1974), we failed to confirm the impressive reductions in bacterial concentrations described by Winitz et al. (1970) with an elemental diet. However, smaller reductions in ‘extremely oxygen-sensitive anaerobes’ and enterococci and minor increases in enterobacteria have been recorded. Alterations in faecal neutral steroids while on Vivonex have also been ascribed to possible changes in microbial flora undetected by present culturing techniques (Crowther et al., 1973). We did not speciate enterococci and changes in this group could have gone undetected. A comparison of preoperative faecal specimens and operative colonic specimens assumes that the colonic is the same as the faecal flora. Although they may not be identical (Hawksworth et al., 1971; Nichols et al., 1971), the differences are not great. Our concern was whether an elemental diet induced important changes in the flora of the large bowel at the site of operation-the site of potential peritoneal contamination-and it does not do this. It would be possible to use this diet with more vigorous mechanical preparation and a short course of oral or perioperative antibacterial agents. A multifaceted approach such as this might result in the
most effectively prepared patients with the lowest infection rate postoperatively.
Acknowledgements We wish to thank Eaton Laboratories for providing Vivonex, Mrs C. Crabtree for technical microbiological assistance and Mr R. F. Galbraith, University of London, for assistance with statistical interpretation. R. B. Ellis-Pegler was the recipient of a research grant from the Wellcome Trust. References and FINEGOLD S. M. (1972) Effect of a partially chemically defined diet on normal faecal flora. Am. J. Cfin. Nutr. 25, 1391-1398. BOUNOUS G . and DEVROEDE G . J . (1974) Effects of an elemental diet on human faxal flora. Gastroenterology 662, 210-214. BURTON R. c . (1973) Postoperative wound infection in colonic and rectal surgery. Br. J. Surg. 60, 363365. COONEY D . R., WASSNER J. D . , GROSFELD J. L. et d. (1974) Are elemental diets useful in bowel preparation? Arch. Surg. 109, 206-210. CROWTHER J. s., DRASAR B. s., GODDARD P. et al. (1973) The effect of a chemically defined diet on the faecal flora and faecal steroid concentration. Gut 14, 790-793. ELLIS-PEGLER R. B., CRABTREE c. and LAMBERT H. P. (1975) The faecal flora of children in the United Kingdom. J . Hyg. (Camb.) 75, 135-142. EVERETT M. T., BROGAN J . D. and NETTLETON J. (1969) The place of antibiotics in colonic surgery: a clinical study. Br. J. Surg. 56, 679-684. GLOTZER D. J., BOYLE P. L. and SILEN w . s. (1973) Preoperative preparation of the colon with an elemental diet. Surgery 745, 703-707. HAWKSWORTH G . , DRASAR B. s. and HILL M. J. (1971) Intestinal bacteria and the hydrolysis of glycosidic bonds, J . Med. Microbiol. 4,451459. HERTER F. P. (1972) Preparation of the bowel for surgery. Surg. Clin. North Am. 52, 859-870. HERTER F. P. and SLANETZ c. A . (1968) Preoperative intestinal preparation in relation to subsequent development of cancer at the suture line. Surg. Gynecol. Obstet. 127, 49-56. HUGHES E. s. R. (1967) Asepsis in large bowel surgery. Med. J . Aust. 2, 663-686, JOHNSON w . c . (1974) Oral elemental diet: a new bowel preparation. Arch. Surg. 108, 32-34. NICHOLS R. L. and CONDON R. E. (1971) Preoperative preparation of the colon. Surg. Gynecol. Obstet. 132, 323-337. NICHOLS R. L., CONDON R . E., GORBACH s. L. et al. (1972) Efficacy of preoperative antimicrobial preparation of the bowel. Ann. Surg. 176, 227-232. NICHOLS R. L., GORBACH s. L. and CONDON R. E. (1971) Alteration of intestinal microflora following preoperative mechanical preparation of the colon. Dis. Colon Rectum 14. 123-127. ATTEBERY H. R., SUTTER V. L.
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