“The effectiveness of a particular antimicrobial drug depends on the etiologic agent and its antibiotic sensitivity. As empiric therapy or to treat a specific bacterial pathogen, first-line antibiotics have traditionally been the fluoroquinolones, such as ciprofloxacin or levofloxacin. Increasing microbial resistance to the fluoroquinolones, especially among Campylobacter isolates, may limit their usefulness in many destinations, particularly South and Southeast Asia, where both Campylobacter infection and fluoroquinolone resistance is prevalent. Increasing fluoroquinolone resistance has been reported from other destinations and in other bacterial pathogens, including in Shigella and Salmonella. In addition, the use of fluoroquinolones has been associated with tendinopathies and the development of C. difficile infection. FDA warns that the potentially serious side effects of fluoroquinolones may outweigh their benefit in treating uncomplicated respiratory and urinary tract infections; however, because of the short duration of therapy for TD, these side effects are not believed to be a significant risk.”
https://wwwnc.cdc.gov/travel/yellowbook/2018/the-pre-travel-consultation/travelers-diarrhea