The colorectal biopsy specimens from 30 patients with chronic watery diarrhoea but normal endoscopic and radiographic findings were studied by light microscopy, morphometry, immunohistochemistry, and two patients with electron microscopy. The histological changes in the colorectum were originally diagnosed in six patients as lymphocytic colitis and in 24 patients as collagenous colitis. The analysis of the specimens for this study could delineate three distinct groups of microscopic colitis: lymphocytic colitis (six patients), collagenous colitis without lymphocytic attack on the surface epithelium (seven patients), and a mixed form presenting with both thickening of the collagen plate and increased number of intraepithelial lymphocytes (17 patients).No transformation was seen from one type to another during follow up of six patients for four to seven years. Increased numbers of active pericryptal myofibroblasts were found with the electron microscope in one patient with mixed microscopic colitis showing also myofibroblasts entrapped within the collagen layer. Hitherto undescribed flat mucosa of the ileum was found in one patient with lymphocytic colitis and both flat mucosa and thickening of the collagen plate in the ileum were seen in one patient with the mixed form of the disease. In another patient with mixed microscopic colitis, normalisation of the colorectal morphology occurred after temporary loop ileostomy, followed by the reappearance of both diarrhoea, inflammation, and thickening of the collagen plate after the ileostomy was reversed. No association was found between non-steroid anti-inflammatory drug (NSAID) consumption and collagenous or mixed microscopic colitis. The primary cause of microscopic colitis is probably an immunological reaction to luminal antigenls, perhaps of ileal origin.

In order to compare the clinical and microbiological efficacies and safety of piperacillin plus tazobactam with those of imipenem plus cilastatin, 134 patients with intra-abdominal infections ( (11,14).Tazobactam is a newly developed P-lactamase inhibitor of the penicillanic acid sulfone class. Its structure is similar to that of sulbactam, except that one of the methyl groups of sulbactam is replaced by a triazolylmethyl group. It is more active than sulbactam against enterobacteria that produce class III and V plasmid-mediated 3-lactamases and is more active than clavulanic acid against those that produce class I chromosomal 3-lactamases (2,7,9).Piperacillin is an extended-spectrum penicillin which has been widely used in the treatment of serious infections. It is active against most enterobacteria and also shows good activity against enterococci and most anaerobic bacteria (5). * Corresponding author. t Scientific coordinators.Recently, the spread of 3-lactamase-producing organisms has raised concerns about the future utility of piperacillin and suggested that it should be used in combination with a 1-lactamase inhibitor such as tazobactam. In vitro studies have shown that piperacillin plus tazobactam is one of the most active penicillin-inhibitor combinations against a wide variety of resistant gram-negative aerobic and anaerobic bacteria (7,9

In order to compare the clinical and microbiological efficacy and safety of meropenem with imipenem/cilastatin, 249 patients with intra-abdominal infections participated in an open randomised comparative multicentre trial. Seventy-five men and 57 women (mean age 51 years) were enrolled in the meropenem group and 67 men and 50 women (mean age 52 years) in the imipenem/cilastatin group. The patients received either meropenem, 500 mg q 8 h, or imipenem/cilastatin, 500 mg/500 mg q 8 h by intravenous infusion for up to 17 days (mean 5 days). Ninety-seven of 99 patients (98%) receiving meropenem were clinically cured while 86 of 90 patients (96%) in the imipenem/cilastatin group were clinically cured. The microbiological response was satisfactory in 89 of 94 evaluable patients (95%) receiving meropenem and in 78 of 81 evaluable patients (96%) receiving imipenem/cilastatin. There was no significant difference in clinical and microbiological efficacy between the two treatment groups. Adverse reactions were noted in 26 patients receiving meropenem and in 36 patients receiving imipenem/cilastatin. The present study shows that meropenem is effective and well tolerated in the treatment of intra-abdominal infections.

The effect of cisapride on postoperative colonic motility was studied in 40 patients undergoing cholecystectomy under randomized, double-blind conditions. The patients received 10 mg of cisapride or placebo by intravenous injection starting on the day of surgery and repeated every 12 h until the 3rd postoperative day. The return of propagative motility in the colon was visualized by means of radiopaque markers and serial abdominal radiographs. Cisapride induced a significantly earlier return of propulsive motility in the right colon, as indicated by the propagation of markers from the ascending colon to the transverse colon (p less than 0.05). Radiopaque markers reached the descending colon (p less than 0.05) and the rectosigmoid colon (p less than 0.05) significantly earlier in the cisapride group than in controls. The first passage of feces occurred significantly earlier in cisapride-treated patients than in controls (p less than 0.05). The first passage of gas after surgery did not differ significantly between the groups. Our results suggest that cisapride can be used to induce earlier return of propagative motility in the colon after major abdominal surgery.