Effects of Magnesium and Calcium Cations on Antibiotic Susceptibility of Pseudomonas aeruginosa.

Background/

Objectives

Pseudomonas aeruginosa is an opportunistic Gram-negative bacterium and a major cause of healthcare-associated infections worldwide, exhibiting intrinsic antimicrobial resistance and readily acquiring novel resistance mechanisms. Divalent cations such as Mg2+ and Ca2+ in the culture environment can influence bacterial antibiotic susceptibility. This study evaluated the impact of varying concentrations of Mg2+ and Ca2+ on the antibiotic susceptibility of P. aeruginosa to tobramycin and ciprofloxacin under both planktonic and biofilm growth modes.

Methods

The study determined the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimum biofilm eradication concentration (MBEC) to compare alterations in antibiotic susceptibility across different ion conditions and bacterial growth patterns.

Results

Our findings suggest that elevated concentrations of Mg2+ and Ca2+ significantly modulate bacterial antibiotic susceptibility.

Conclusions

The results of our study has implications for limitations in standardised antibiotic susceptibility tests and to therapeutic strategies in cation-rich environments such as cystic fibrosis airways.