Chinese scientists have investigated the presence of a rare but dangerous bacteria in mushroom products.
Burkholderia gladioli pathovar cocovenenans can cause lethal poisoning. Most cases have been reported in China, primarily from fermented cereal products.
Symptoms include abdominal pain, diarrhea, vomiting, weakness, and palpitations. From 2005 to 2020, 30 foodborne outbreaks were reported, resulting in 85 deaths.
Burkholderia gladioli pathovar cocovenenans causes poisoning by producing bongkrekic acid, which cannot be destroyed by cooking.
The study, published in China CDC Weekly, details contamination in commercial fungi and analyzed the environmental conditions for bongkrekic acid production.
Detection rate in samples
Dried black fungus and dried Tremella fuciformis, an edible mushroom, were soaked in sterile water for a range of time periods and temperatures. Scientists said people should avoid eating fungi products soaked 24 hours or more, no matter the temperature.
A total of 85 food samples were collected from Shanghai markets in 2023. Sixty were purchased from markets in Xuhui, Changning, and Minhang Districts, while 25 were from online shops in Shanghai.
Overall, in 38 of 85 samples, Burkholderia gladioli was detected. The highest detection rate was in dried black fungus with 34 of 36 positives, followed by fresh Tremella fuciformis with two of 12 positives, and fresh black fungus and dried Tremella fuciformis with one positive each.
Burkholderia gladioli pathovar cocovenenans was found in 14 of 36 samples of dried black fungus. A range of bongkrekic acid concentrations were found.
Previous research found the optimal temperature and pH for Burkholderia gladioli pathovar cocovenenans growth are 37 degrees C (98.6 degrees F) and pH of 6, while for bongkrekic acid, these figures are 30 degrees C (86 degrees F) and a pH of 7.
Findings indicate that Burkholderia gladioli pathovar cocovenenans isolates possess varying capabilities for bongkrekic acid production.
“Controlling contamination in raw materials is crucial for preventing Burkholderia gladioli contamination in dried black fungus and Tremella fuciformis,” said scientists.
Citrobacter risk
Meanwhile, another study has linked Citrobacter to two incidents in East China in August 2022 and October 2023.
Scientists investigated the role of Citrobacter portucalensis and Citrobacter freundii as opportunistic pathogens in foodborne diarrhea outbreaks. Results were published in the journal Food Microbiology.
Two food poisoning incidents were reported by the local Centers for Disease Control and Prevention in East China. One outbreak caused diarrhea and vomiting in 23 employees of two companies, and the other affected high school students, with no common pathogens isolated in the initial test.
“This study underscores the importance of monitoring Citrobacter species in the context of food safety and emphasizes the neglected emerging pathogens implicated in these outbreaks in the region,” said researchers.
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