Association of Laribacter hongkongensis in community-acquired gastroenteritis with travel and eating fish: a multicentre case-control study.

BACKGROUND: Laribacter hongkongensis has been recovered from several patients with gastroenteritis. However, the causative role of this organism in human gastroenteritis is still unproven, and sources of the bacterium are unknown. We undertook a multicentre case-control study to investigate the association of L hongkongensis with gastroenteritis.
METHODS: Faecal samples from patients with community-acquired gastroenteritis and controls were cultured for L hongkongensis. Targeted food surveillance was done to identify potential sources of this bacterium. All isolates of this organism from patients and food items were characterised by pulsed-field gel electrophoresis and ribotyping.
FINDINGS: During a 4-month period, L hongkongensis was recovered from 17 of 3788 patients with community-acquired gastroenteritis, but was absent in 1894 controls (p=0.001). Those who were culture-positive for this bacterium had a recent history of travel (ten [59%] patients vs two [6%] of 34 matched controls, p<0.0001), of fish consumption (16 [94%] vs 19 [56%], p=0.009), and of eating minced freshwater fish meat (five [29%] vs one [3%], p=0.012). We recovered 25 L hongkongensis isolates from intestinal samples of freshwater fish and two from minced freshwater fish meat. Bacteria with the same pulsed-field gel electrophoretic pattern and ribotype were recovered from one patient and a sample of minced freshwater fish meat, which was from the same retail market recently visited by the patient. We did not see this particular combination of electrophoretic pattern and ribotype in any other isolates.
INTERPRETATION: L hongkongensis is associated with community-acquired gastroenteritis and traveller's diarrhoea. However, its causative role has not been shown. Freshwater fish is one source of this bacterium.