Transmission of ESBL-producing bacteria mainly through pollution

Human contamination is probably the most frequent transmission route of ESBL-producing bacteria. Transmission through the food chain hardly seems to play a role. Researchers from the European MODERN WP3 study group conclude that after analyzing samples from sewers, polluted rivers and food. The research was published in Clinical Microbiology and Infection.

Extended-spectrum β-lactamase productionende Enterobacterales (ESBL-PE) are a major cause of the spread of antibiotic resistance. Escherichia coli (ESBL-Ec) and Klebsiella pneumoniae (ESBL-Kp) are two bacterial species that play an important role in this. These cause infections with third-generation cephalosporin-resistant bacteria in humans. This limits the treatment options for patients.

Food as a source?

The aim of the study was to find out to what extent food is a source of ESBL-Ec and ESBL-Kp. For this purpose, 122 polluted environments (sewers and polluted rivers) and 714 foodstuffs were sampled. This happened in 5 European cities: Besançon (France), Geneva (Switzerland), Seville (Spain), Tübingen (Germany) and Utrecht (Netherlands). Thus, 254 ESBL-Ec and 39 ESBL-Kp isolates were cultured. The genomes of these were completely sequenced in order to compare sequence types and genetic profiles. The distribution of . was also examined bla_ESBL genes and their carriers (chromosome or plasmid).
The sequence data showed that isolates of ESBL-Ec and ESBL-Kp from contaminated environments are genetically different from isolates from food. For example, isolate ESBL-Ec ST131 was widespread in contaminated environments, but did not occur in tested foods. Also the distribution of bla_ESBL genes differed between polluted environment and food.

Hardly any connection

The researchers conclude that there is hardly any association between ESBL-Ec and ESBL-Kp populations from food and from contaminated environments. This suggests that in Western countries, not the food chain, but rather human-to-human contamination is probably the most frequent route of transmission of ESBL-Ec and ESBL-Kp.

Bron:
Martak D, Guther J, Verschuuren TD, et al. Populations of extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae are different in human-polluted environment and food items: a multicentre European study. Clin Microbiol Infect, 2022;28:447.e7-447.e14.