# The Invisible Threat of Antibiotic Resistance in Food
## 2 Antibiotics and Their Effects on Bacterial Resistance
It was demonstrated that the number of _Staphylococcus_ and _Enterobacteriaceae_ resistant to streptomycin, methicillin, tetracycline, and gentamicin is high in meat, meat products, and the milk of cows treated with sub-therapeutic concentrations of antibiotics in South Africa [33]. Several other studies also confirm the link between low antibiotic exposure and the development of resistance. These include many milk-related publications. In a Greek study, tetracycline resistance was 50% in _E. coli_ strains isolated from cheese [34]. A Chinese study reported the resistance of _Bacillus cereus_ strains isolated from milk to ampicillin (99%), penicillin (99%), and cefoxitin (95%) [35]. In an assay of Iranian milk samples, pathogenic _E. coli_ isolates showed high resistance to tetracycline(84%) and penicillin (46%) [36]. Likewise, high levels of resistance of pathogenic isolates were found in milk samples from other areas of Iran [37]. _Salmonella_ isolates were highly resistant to penicillin (100%), cephalexin (100%), and amoxicillin (71.42%), while isolates of _S. aureus_ were highly resistant to amoxicillin (100%), cephalexin (100%), and penicillin (84.00%). Moreover, 67% of pasteurized and unpasteurized milk samples from Kenya [38] contained ampicillin- and/or tetracycline-resistant _E. coli_. In the case of milk samples examined in Indonesia [39], the prevalence of _S. aureus_ was 55.2%, and that of _E. coli_ was 70.4%. A total of 7.4% of the isolates contained the _mecA_ gene (MRSA) and 100% of the _E. coli_ strains were EBL producers. During the investigation of the antibiotic resistance profile of milk sample isolates carried out in Egypt, it was found that 86.11% of the strains were multi-resistant [40]. In the study of [PERSON] et al. [41], 44 _Salmonella_ isolates were recovered from 280 Egyptian cheese samples. All isolates harbored virulence genes of _invA_, _stn_, and _hillA_. The highest resistance was found to be erythromycincin and clindamycin (90.91%), as well as ceftazidime and cephalothin (84.09%). The majority of MDR isolates (79.55%) showed narrow spectrum (NS), had extended-spectrum (ES), and _AmpC-BLR_ genes. Table 1 summarizes the types of food products that were reported to contain antibiotic-resistant bacteria. In Table 2, the most frequent and hazardous foodborne pathogenic bacteria are presented, which highlights their broadspectrum antibiotic resistance. They are among the top five foodborne pathogens that cause illnesses in the U.S. [42; 43; 44]. These were nontynboidal _Salmonella_ spp. (11%), _Clostridium perfingens_ (10%), and _Campylobacter_ spp. (9%). Those foodborne pathogenic bacteria among the top five foodborne pathogens reported to cause the highest number of death cases in the U.S. [42; 43] were nontynboidal _Salmonella_ spp. (28%) and _Listeria monocytogenes_ (19%). The top five confirmed foodborne infections, hospitalizations, and case fatalities were caused by _Campylobacter_ spp., _Salmonella_ spp., _Yersinia_ spp., VTEC, and _Listeria monocytogenes_ in the European Union and the U.S. [43].