Diagnostic low-dose X-ray radiation induces fluoroquinolone resistance in pathogenic bacteria.

PURPOSE

The crisis of antibiotic resistance has been attributed to the overuse or misuse of these medications. However, exposure of bacteria to physical stresses such as X-ray radiation, can also lead to the development of resistance to antibiotics. The present study aimed to investigate the effect of exposure to diagnostic low-dose X-ray radiation on the bacterial response to antibiotics in two pathogenic bacteria, including the Gram-positive and Gram-negative .

METHODS

The bacterial strains were exposed to diagnostic X-ray doses of 5 and 10 mGy, which are equivalent to the doses delivered to patients during conventional radiography X-ray examinations in accordance with the European guidelines on quality criteria for diagnostic radiographic images. Following exposure to X-ray radiation, the samples were used to estimate bacterial growth dynamics and perform antibiotic susceptibility tests.

RESULTS

The results indicate that exposure to diagnostic low-dose X-ray radiation increased the number of viable bacterial colonies of both and and caused a significant change in bacterial susceptibility to antibiotics. For instance, in , the diameter of the inhibition zones for marbofloxacin decreased from 29.66 mm before irradiation to 7 mm after irradiation. A significant decrease in the inhibition zone was also observed for penicillin. In the case of , the diameter of the inhibition zone for marbofloxacin was 29 mm in unexposed bacteria but decreased to 15.66 mm after exposure to 10 mGy of X-ray radiation. Furthermore, a significant decrease in the inhibition zone was detected for amoxicillin and amoxicillin/clavulanic acid (AMC).

CONCLUSION

It is concluded that exposure to diagnostic X-ray radiation can significantly alter bacterial susceptibility to antibiotics. This irradiation decreased the effectiveness of fluoroquinolone and β-lactam antibiotics. Specifically, low-dose X-rays made resistant to marbofloxacin and increased its resistance to penicillin. Similarly, Enteritidis became resistant to both marbofloxacin and enrofloxacin, and showed reduced sensitivity to amoxicillin and AMC.