April 28, 2015

60% of US raw shrimp contaminated with bacteria, study finds

A study by US-based consumer NGO Consumer Reports found that 60% of raw shrimp at retail outlets tested positive for bacteria.

The motivation for the study was the fact that the Food and Drug Administration tested only 0.7% of foreign shrimp shipments last year.

The NGO tested for bacteria such as salmonella, vibrio, Staphylococcus aureus, and E. coli. It also looked for drug residues to see whether antibiotics were used in raising the shrimp.

Antibiotics, of which none are approved by the US for shrimp farming and which are illegal in imported shrimp, are problematic because their use can ultimately lead to bacteria becoming antibiotic-resistant.

Consumer Reports says its findings provided some cause for concern. In 16% of cooked, ready-to-eat shrimp, it found several bacteria, including vibrio and E. coli. In 11 samples of raw imported farmed shrimp, it detected antibiotics. And in seven raw shrimp samples, it found MRSA - methicillin-resistant Staphylococcus aureus, a bacteria that can cause infections that are often difficult to treat with some antibiotics.

While 60% of raw shrimp tested positive for bacteria, Consumer Reports highlighted the importance to keep those findings in perspective. By comparison, in 2013, when the NGO tested raw chicken breasts, 97% of the samples contained bacteria.

Compared with the chicken samples, far fewer shrimp contained salmonella, which is often responsible for outbreaks of food poisoning. But of concern, it found vibrio on many shrimp samples.

"Vibrio is the most common cause of food poisoning from eating raw oysters," says Urvashi Rangan, Ph.D., executive director of the Consumer Reports Food Safety and Sustainability Centre. "And even though most bacteria on shrimp would be killed during the cooking process, our test results raise real questions about how shrimp is raised, processed, and regulated."

The organisation's experts also say more should be done to prevent contamination, but note that cooking should kill bacteria.