Infective colitides
Infective colitides
Infective causes may be classified as bacterial, protozoal, viral and fungal. Common infections include the following. Escherichia coli E. coli is a Gram-negative bacillus transmitted via the faeco - oral route from contaminated food or water. Symptoms vary according to strain, with the most common form – entero - toxigenic E. coli – causing ‘traveller’s’ diarrhoea (diarrhoea, vomiting and colicky pain). In adults, infection is usually brief and self-limiting. A more severe form – enteroinvasive - E. coli – causes a more systemic illness and haematochezia. A very severe form – enterohaemorrhagic E. coli – results in colonic oedema, ulceration and haemorrhage with the very ill requiring colectomy . Campylobacter Infection with Campylobacter jejuni (a Gram-negative rod with a distinctive spiral shape) is the most common form of gastro - enteritis in resource-rich countries, typically acquired from eating infected poultry . It causes diarrhoea and abdominal pain. Severe cases may resemble ulcerative colitis. The organism supportive as it usually resolves without antibiotics, but severe colitis and even perforation may occur. Salmonellosis, typhoid and paratyphoid Salmonella are a family of Gram-negative rods that can cause a range of enteric infections. Salmonella gastroenteritis is typically caused by Salmonella enteritidis from poultry and is most often a self-limiting illness comprising headache, fever and watery diarrhoea. When severe, antibiotics, hospitalisation and intravenous fluids may be needed. The diagnosis is based on stool culture. Shigella and enteropathogenic strains of may cause similar diarrhoeal illnesses. Typhoid fever is caused by Salmonella enterica Typhi and paratyphoid fever by Salmonella enterica Paratyphi A, B or C. The clinical di ff erences between these infections are subtle. They present with fever and abdominal pain after a 10- to 20-day incubation period. Over the next week, the patient can develop distension, diarrhoea, splenomegaly and characteristic ‘rose spots’ on the abdomen caused by a vasculitis. A number of surgical complications can result: /uni25CF paralytic ileus; /uni25CF intestinal haemorrhage; /uni25CF perforation; /uni25CF cholecystitis. In addition, invasion of the systemic circulation, which is a characteristic feature of salmonellosis, can cause severe Gram-negative sepsis and septic shock may develop. Occasion ally patients develop metastatic sepsis, including septic arthri tis, osteomyelitis, meningitis, encephalitis and pancreatitis. Ye r s i n i a Yersinia , Gram-negative coccobacilli, infection results from ingestion of contaminated food, typically meat, water and dairy products. Invasion typically occurs in the ileocaecal region and may mimic Crohn’s disease. Treatment is usually supportive with antibiotics reserved for severe infection or in the immunocompromised. Shigella (bacillary dysentery) Dysentery results from the ingestion of contaminated food or water, with only a small dose of infective agent required. The Gram-negative bacilli invade the colonic epithelium, causing cell death, ulceration and necrosis. Exotoxins cause a brief period of watery diarrhoea before the onset of classical severe, bloody diarrhoea. Clostridium difficile Clostridium di ffi cile is a toxin-producing Gram-positive bacillus that is of increasing concern in many hospitals. Although normally present in around 2% of the population, it proliferates after antibiotic treatment (especially with cephalosporins). Clinically , C. di ffi cile infection presents with diarrhoea, abdominal pain and fever. Infection may progress to pseudomembranous colitis, so called because on endoscopic Burrill Bernard Crohn , 1884–1983, gastroenterologist, Mount Sinai Hospital, New Y ork, NY , USA, described regional ileitis in 1932 along with Leon Ginzburg and Gordon Oppenheimer. between oedematous mucosa are seen. Diagnosis is usually made by detection of the toxin in stool samples, rather than by culture. Treatment is by metronidaz ole or vancomycin along - side supportive care. In refractory cases, faecal transplantation to restore a healthy microbiota may be tried. If toxic dilatation occurs, an emergency subtotal colectomy and ileostomy ma y be necessary . Recently more virulent strains have stressed the importance of prevention. Suspicion of the disease should prompt source isolation, protective equipment for health sta ff , vigorous disin - E. coli fection and scrupulous hand washing. Intestinal amoebiasis Entamoeba histolytica has a worldwide distribution and is trans - mitted mainly in contaminated drinking water. It can cause colonic ulcers, described as ‘bottlenecked’ because they have considerably undermined edges. The ulcers typically also have a yellow necrotic floor, from w hich blood and pus exude. In the majority they are confined to the distal sigmoid colon and the rectum. Clinically amoebiasis can mimic ulcerative colitis, most commonly causing bloody diarrhoea. Severe colonic compli - cations can occur, including haemorrhage, stricture formation or perforation. A pericolitis is not uncommon and results in adhesions that may cause intestinal obstruction. Amoebiasis may cause liver abscesses or an amoebic mass (‘amoeboma’) of the caecum or sigmoid, whic h is di ffi cult to distinguish from a carcinoma. Surgery is fraught with danger as the bowel is - extremely friable. - Endoscopic biopsies or fresh stools are examined to look for the presence of amoebae ( Figure 77.12 ). It is important to emphasise, however, that the presence of the parasite does not indicate that it is pa thogenic. It is especially important to exclude amoebic infection in patients suspected of having ulcerative colitis. Treatment is by metronidazole in the acute phase. Diloxanide furoate is e ff ective against chronic infections associated with the passage of cysts in stools.
Figure 77.12 An amoeba in a rectal biopsy (arrow).
Cytomegalovirus (CMV) is present asymptomatically in 40–100% of adults. It usually remains latent within the host but can reac tivate in immunocompromised patients. Commonly a ff ected are those with acquired immunodeficiency syndrome (AIDS) (where it is the most common indication for colectomy) and patients on imm unosuppressive therapy for IBD. Symptoms include profuse bloody diarrhoea and colicky pain. Severe disease may lead to perforation. Treatment is with ganciclovir with surgery necessary for severe disease or complications. Human immunodeficiency virus Intestinal complications are common after the develop ment of AIDS when opportunistic organisms can cause gas troenteritis ( Summary box 77.9 ). Human immunodeficiency virus 1 (HIV1) may also cause a specific enteropathy . Treat ment is directed towards the responsible organism and surgery should be a voided. Summary box 77.9 Opportunistic intestinal infections in patients with AIDS /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF
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