Acute diarrhoea For Fourth- year Medical students Dr: Hussein Mohammed Jumaah CABM Mosul Medical College 28/11/2013

Diarrhoea Passage of abnormally liquid stools at an increased frequency. For adults stool weight 200 g/d. Infective diarrhoea Is usually short-lived lasting <10 days.

Causes of infectious gastroenteritis Toxin in food: < 6 hours incubation Bacillus cereus Staph. Aureus Clostridium spp. enterotoxin Bacterial: 12-72 hours incubation Vibrio cholerae Enterotoxigenic E. coli Shiga toxin-producing E. coli Enteroinvasive E. coli Salmonella Shigella Campylobacter Clostridium difficile Viral: short incubation Rotavirus Norovirus "winter vomiting disease" Protozoal: long incubation Giardiasis Cryptosporidium Microsporidiosis Amoebic dysentery Isosporiasis The majority of episodes are due to infections spread by the faecal-oral route .

The clinical features depend on the Organisms , Bacillus cereus, S.aureus and Vibrio cholerae, elute exotoxins, which exert their major effects on the stomach and small bowel, and produce vomiting and/or so-called secretory diarrhoea, watery without blood or faecal leucocytes. The incubation period is short and little systemic upset occurs.

Shigella, Campylobacter and enterohaemorrhagic E Shigella, Campylobacter and enterohaemorrhagic E. coli (EHEC) ,may directly invade the mucosa of the small bowel or produce cytotoxins that cause mucosal ulceration, typically affecting the terminal small bowel and colon. The incubation period is longer and more systemic upset occurs, with prolonged bloody diarrhoea.

Salmonella spp. are capable of invading enterocytes, and of causing both a secretory response and invasive disease with systemic features. This is seen with Salmonella typhi and S. paratyphi (enteric fever), and, in the immunocompromised host, with non-typhoidal Salmonella spp.

Clinical assessment The history ,include foods ingested, duration and frequency of diarrhoea, the presence of blood, abdominal pain and tenesmus, and whether other members have been affected. Fever and bloody diarrhoea suggest an invasive disease.

Examination Assessment of the degree of dehydration by skin turgor, pulse and blood pressure, urine output. Investigations Stool inspection for blood and microscopy for leucocytes, and also an examination for ova, cysts and parasites . Stool culture should be performed. FBC and serum electrolytes indicate the degree of inflammation and dehydration.

Management Patients with acute, potentially infective diarrhoea should be appropriately isolated to minimise spread. If the history suggests a food-borne source, public health measures must be implemented to identify the source .

Fluid replacement The fluid lost in diarrhoea is isotonic. Absorption of electrolytes from the gut is an active process requiring energy. Infected mucosa is capable of very rapid fluid and electrolyte transport if carbohydrate is available as an energy source.Oral rehydration solutions (ORS) therefore contain sugars, as well as water and electrolytes . Intravenous fluid if there is vomiting. Those with cardiac or renal disease, monitoring of urine output and central venous pressure may be necessary.

The volume of fluid replacement Replacement of established deficit. After 48 hours of moderate diarrhoea (6-10 stools per 24 hours) the average adult will lose 1-2 L, vomiting will compound this, rapid replacement of 1-1.5 L, either orally (ORS) or by IV normal saline, within the first 2-4 hours Replacement of ongoing losses. The average adult's diarrhoeal stool accounts for a loss of 200 mL of isotonic fluid. Rehydration sachets provide 200 mL of ORS; one sachet per diarrhoea stool is an appropriate replacement. Replacement of normal daily requirement Adult daily requirement of 1-1.5 L of fluid,increased substantially in fever or a hot environment.

Antimicrobial agents In non-specific gastroenteritis, antibiotics have been shown to shorten symptoms by only 1 day. This benefit, when related to the potential for the development of antimicrobial resistance or side-effects, does not justify treatment. Evidence suggests that, in EHEC infections, the use of antibiotics may make the complication of haemolytic uraemic syndrome more likely due to increased toxin release. Antibiotics should therefore not be used routinely in bloody diarrhoea.

Conversely, antibiotics are indicated in Sh. dysenteriae infection and invasive salmonellosis, in particular typhoid fever. Antibiotics may also be advantageous in cholera epidemics, reducing infectivity and controlling the spread of infection. If there is systemic involvement and a host with immunocompromise or significant comorbidity. Antidiarrhoeal, antimotility and antisecretory agents are not recommended in acute infective diarrhoea and their use may even be contraindicated.

Bacillary dysentery (shigellosis)

Bacillary dysentery (shigellosis) Gram-negative rods. Four main groups: Sh. dysenteriae, flexneri, boydii and sonnei. In the tropics bacillary dysentery is usually caused by Sh. flexneri. The organism only infects humans and its spread is facilitated by its low infecting dose of around 10 organisms. Spread may occur via contaminated food or flies, but transmission by unwashed hands after defecation is by far the most important factor. Outbreaks occur in mental hospitals, and other closed institutions.

Clinical features Disease severity varies from mild Sh. sonnei infections that may escape detection to more severe Sh. flexneri infections, while those due to Sh. dysenteriae may be fulminating and cause death within 48 hours.

In a moderately severe illness, the patient complains of diarrhoea, colicky abdominal pain and tenesmus. Stools are small, and after a few evacuations contain blood and purulent exudate with little faecal material. Fever, dehydration and weakness occur, with tenderness over the colon. Arthritis or iritis may occasionally complicate bacillary dysentery (Reiter's syndrome), associated with HLA-B27.

Management Oral rehydration therapy or, if diarrhoea is severe, intravenous replacement of water and electrolyte loss is necessary. Antibiotic therapy with ciprofloxacin (500 mg 12-hourly for 3 days). Antidiarrhoeal medication should be avoided. prevention The prevention of faecal contamination of food and milk. The isolation of cases may be difficult, except in limited outbreaks. Hand-washing is very important.

Differences Between Amebic &Bacillary Dysentery