shigella

see also:

• gastroenteritis
• traveller's diarrhoea

• Shigellosis is an infectious gastroenteritis usually causing dysentery-type pattern
• Shigella are Gram-negative, facultative anaerobes
  • it is endemic in developing countries were sanitation is poor resulting in around half of cases of bloody diarrhoea / dysentery in young children in those areas
  • in developed countries, single-source, food or water-borne outbreaks occur sporadically
• transmission of Shigella is by the faecal-oral route
• ingestion of a very low number of bacteria can cause infection
• incubation period is usually one to three days
• cases remain infectious while bacteria are continuing to be shed in the faeces, which can last for up to four weeks after symptoms resolve, although rarely, the carrier state may persist for months or longer
• appropriate antibiotic treatment usually reduces the duration of carriage to a few days and is an appropriate public health measure

• men who have sex with men
• travelers from overseas

• two main presentations with onset within 24-48hrs of ingestion:
  • watery diarrhea associated with vomiting and mild to moderate dehydration
  • dysentery characterized by a small volume of bloody, mucoid stools, and abdominal pain (cramps and tenesmus)
    • this may be preceded by a watery diarrhoea prodrome
• typically, stools contain blood, mucus and pus
• some people will present with watery diarrhoea without these features
• convulsions have been reported in up to 25% of Shigella infections involving children under the age of 4 years
• symptoms generally last 7 days untreated and perhaps 2 days less if antibiotics are used to which the organism is sensitive
• sigmoidoscopic examination of a shigellosis patient reveals a diffusely erythematous mucosal surface with small ulcers and resemble those of ulcerative colitis
• Ekiri syndrome, an extremely rare, fatal encephalopathy has also been described in Japanese children with S sonnei or S flexneri infections
• self-limiting reactive arthritis may occur in 2% of S flexneri infections of individuals expressing the HLA-B27 histocompatibility antigen
• rarely, haemolytic-uraemic syndrome, characterized by a triad of microangiopathic haemolytic anemia, thrombocytopaenia, and acute renal failure, is a rare complication in children infected with S dysenteriae serotype 1
• may also cause:
  • raised WCC with left shift
  • leukopenia
  • anaemia
  • thrombocytopenia
  • hyponatraemia
  • hypoglycaemia
  • raised C reactive protein (CRP)
  • raised erythrocyte sedimentation rate (ESR)
  • acute kidney injury (AKI) / acute renal failure (ARF)
  • mildly raised bilirubin

• stool culture - ensure stool samples are sent for culture and antibiotic sensitivity testing in order to guide appropriate antibiotic treatment as antibiotic resistance is increasing

• supportive care
• gastro precautions
• prevent transmission to others
  • it is a notifiable disease in Victoria!
    • medical practitioners must notify the department of all cases of suspected and confirmed shigellosis, and should advise confirmed cases who are food handlers, child care workers and health care workers not to work pending further advice from the department.
  • because of the small infectious dose, people with shigellosis who work as food handlers, childcare workers, health care workers, or workers in a residential facility should be excluded from work until advised by the Local Public Health Unit
  • thoroughly wash hands after going to the toilet and before eating or preparing food
  • not prepare food for others until 48 hours after symptoms completely resolve
  • avoid having sex for seven days after symptoms completely resolve
  • given the increasing antibiotic resistance, although antibiotics can be used to reduce stool shedding, they should now be reserved for those with severe disease
    • in Victoria, 2016, resistance levels were: 64% resistant to ampicillin, 87% to trimethoprim, 49% to azithromycin and 20% to ciprofloxacin ¹⁾
    • check sensitivities BEFORE starting Rx