The indiscriminate use of antibiotics for the treatment of human and animal infections has led to the rise of resistance in pathogens and in commensal bacteria. In particular, farm animals may act as vectors for the dissemination of drug-resistant genes because of the intensive use of antibiotics in animal production, enabling resistance to a wide range of antimicrobial agents, including those normally used in human medicine. Escherichia coli, being a widespread commensal, is considered a good indicator of antibiotic use. Ultimately, it is emerging as a global threat, developing dramatically high levels of antibiotic resistance to multiple classes of drugs. Its prevalence in food animals is hence alarming, and more studies are needed in order to ascertain the spread dynamics between the food chain and humans. In this context, great attention should be paid to the accurate detection of resistance by conventional and molecular methods. In this review, a comprehensive list of the most widely used testing methods is also addressed.