The Dutch National Institute for Public Health and the Environment (RIVM) calculated to what degree different types of meat contribute to the exposure of humans to ESBL-producing bacteria.
They found beef was responsible for 78% of total exposure resulting from eating meat. This is due to some beef products being eaten raw such as steak tartare.
More bacteria on chicken
However, ESBL-producing bacteria are found most often on raw chicken meat.
As it is usually cooked before consumption, exposure via this pathway is much lower (18%).
RIVM said people can become exposed as a result of cross contamination in the kitchen, for example by cutting chicken and vegetables with the same knife and/or on the same cutting board.
ESBL is an enzyme produced by bacteria that breaks the structure of certain types of antibiotics (penicillins and cephalosporins).
Bacteria that are capable of producing ESBLs are often commensal intestinal bacteria (Klebsiella, E. coli). The ability to produce the ESBL enzyme does not increase a bacterium's pathogenic capability.
The extent of exposure via meat compared with other routes of infection is unknown and was not investigated in the study.
It is unclear if exposure leads to carriage of the bacteria or potential human health burden.
Calculations take into account various factors that affect the presence of bacteria on meat: pre-processing (heating, salting, drying/fermenting), storage conditions (room temperature, refrigerator, freezer), and method of preparation (raw, thoroughly cooked, half cooked, the degree of cross contamination, etc).
They were made using a risk model, sQMRA (swift Quantitative Microbiological Risk Assessment).
Data from the Dutch National Food Consumption Survey (Nederlandse Voedselconsumptiepeiling) 2005-2012 was used.
RIVM said there is no evidence that people who eat meat carry more ESBL-producing bacteria in their gut than those who do not.
About 5% of the Dutch population carries ESBL-producing bacteria in the gut.
Examples of other sources of exposure include contacts with animals, between people, other types of food such as raw vegetables and fruit and through the environment.
The study involved literature research and no new laboratory tests were performed.
RIVM recommended follow-up research aimed at estimating the human disease burden caused by ESBL and the relative contribution of food in relation to other transmission routes.