The incidence of ciprofloxacin-resistant Salmonella has increased considerably over the past decade. This study aimed to explore interactions among genetic determinants defining ciprofloxacin resistance in Salmonella including the efflux pump and plasmids. After treatment with PAβN (a resistance nodulation-division efflux pump inhibitor), a decline ranging from 4–32-fold in minimum inhibitory concentration (MIC) was observed in all 18 ciprofloxacin-resistant Salmonella isolates tested. Particularly, all the strains without point mutations changed from resistance to sensitivity. Moreover, the efflux pump is critical for fluoroquinolone resistance development in serovar Enteritidis because of a larger range reduction (16 or 32-fold) caused by the inhibition in the five S. Enteritidis strains carrying a GyrA (Asp87Tyr) mutation with relatively high MICs (8 μg/mL). Genes oqxAB and aac(6′)-Ib-cr located on incompatibility (Inc) F-type plasmids in S. Enteritidis, IncA /C in S. Typhimurium and Inc HI2 in S. Virchow were transferable, while qnrS1 and/or qepA were driven by the Inc A/C type in S. Thompson. Whole-genome sequencing showed that an oqxAB module was detected in the chromosomal DNA of S. Derby. Moreover, the MIC of ciprofloxacin in the transconjugants/transformants remained low (1-4 μg/mL) but was above the breakpoint level, implying that plasmid-borne determinants might confer relatively low-level resistance to allow their host to survive long enough to develop high level resistance. These findings emphasize that both the efflux pump and the transmission of plasmid-borne resistance mechanisms could contribute to the sharp increase in the occurrence of ciprofloxacin resistance and pose a considerable threat to food safety.