What is "retail food chain"?

Context:

Advanced cephalosporins can no longer be used as empirical therapy in many countries. Hence, carbapenems, an antibiotic class that represents the last available weapon against many gram-negative bacilli, are being used increasingly for empirical therapy. Resistance to these agents will accelerate if carbapenems become standard first-line therapy worldwide, particularly in intensive care, where selective pressure and transmission risks are highest. Pseudomonas aeruginosa and Acinetobacter species can be highly resistant to ceftazidime, fluoroquinolones, and carbapenems. An increasing number of organisms are resistant to all antibiotics, including colistin12. K pneumoniae and E coli will probably become increasingly resistant to carbapenems by harbouring carbapenemases or nucleoside diphosphate enzymes, such as the New Delhi metallo-betalactamase (NDM1) 13. The spread of these resistant gram-negative organisms should be regarded as a growing but insufficiently publicised pandemic.Some drug resistance among Enterobacteriaceae came from the use of antibiotics in animals in the retail food chain. E coli and Salmonella strains resistant to fluoroquinolones and third-generation cephalosporins 14 have been associated with meat and poultry products.