Invasive Group B Streptococcus Infection associated with Sequence Type 283 (ST283)

Causative agent

Group B Streptococcus (GBS), Streptococcus agalactiae, is an encapsulated gram-positive non-motile coccus bacterium. It is widely distributed among diverse species including humans, mammalian animals, amphibians, reptiles and fishes. A specific strain of GBS, the Sequence Type 283 (ST283), was among the more virulent strains of GBS and caused invasive diseases in many otherwise healthy adults or adults with relatively few underlying comorbidities.

Presence of GBS ST283 was reported in freshwater fish, in particular farmed fish, in Southeast Asian countries with prevalence reported to be ranging from 12.5% to 100%. In 2015, GBS ST283 caused a major invasive foodborne outbreak involving at least 146 people in Singapore. Epidemiological investigations showed that the outbreak had a strong link with the consumption of raw freshwater fish and this has led to a ban in the use of raw freshwater fish in all ready-to-eat raw fish dishes in Singapore since December 2015. Thereafter, invasive GBS ST283 disease has also been reported in other countries and areas in and around Southeast Asia including the Mainland China, Hong Kong SAR, Lao People’s Democratic Republic, Thailand, and Vietnam.

Clinical features

Invasive GBS infection may present as sepsis, meningitis, septic arthritis, infective endocarditis and even death.

Mode of transmission

The sources of invasive Group B Streptococcal infection associated with ST283 are mostly unclear. Literature reported that it relates to eating or improper handling of contaminated food, and some even reported that invasive Group B Streptococcus ST283 exists in freshwater fish, especially cultured fish.

High risk groups

Generally speaking, the elderlies and immunocompromised people may be at higher risk.

Management

Invasive Group B Streptococcus infection can be treated with antibiotics.

Prevention

To prevent Group B Streptococcus (ST283) infection, members of the public are reminded to maintain personal, food and environmental hygiene and should keep their hands clean and practice good wound care at all times, especially:

• To minimise the infection risks, workers of aquatic products or restaurants must wear gloves when handling aquatic products and avoid direct contact with aquatic products or dirty water with bare hands;
• When buying aquatic products, the public must avoid direct contact with the aquatic products or use any towel provided by the stalls. They should wash hands with liquid soap and water as soon as possible if having contact with aquatic products which are not fully cooked. When handling aquatic products at home, the public should also wear gloves and wash hands thoroughly afterwards;
• Members of the public must not eat any freshwater fish sashimi, raw or undercooked freshwater aquatic products. When consuming hot pot food or congee items which consist of aquatic products, they should ensure that the food is thoroughly cooked in which the centre of the food should reach a temperature of at least 75 degrees Celsius so as to destroy pathogen; and
• People must not touch aquatic products directly whenever there is a wound on hands. If a wound is sustained during handling aquatic products, the wound must be cleaned immediately and properly covered with waterproof adhesive dressings. Individuals should seek medical advice promptly when wound infection is found.

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