The Effects of Growth Rate on Antibiotic Resistance in Pseudomonas aeruginosa

The Effects of Growth Rate on Antibiotic Resistance in Pseudomonas aeruginosa

Antibiotic resistance is a global health crisis. The overuse of antibiotics to treat bacterial infections has led to rapid pathogen adaptation, which has resulted in reduced treatment efficacy. This, in turn, can lead to adverse consequences such as prolonging the duration and expense of a patient’s hospital stay,infecting immunocompromised individuals leading to further health complications, and increasing the occurrence and severity of side effects due to necessitated use of higher doses of medications. One opportunistic pathogen that has shown increased resistance to several antibiotics is the biofilm forming bacteria Pseudomonas aeruginosa. In order to grow, and resist antibiotics, P. aeruginosa engages in cooperative behaviors, including the release of pyoverdine, a siderophore that promotes growth. Recent findings have suggested that the growth rates of some bacteria are directly linked to antibiotic resistance. Higher growth rates facilitate resistance; however, this has yet to be shown for P. aeruginosa. To address this open question, we used microplate reader assays to examine the effect of growth rate on minimum inhibitory concentrations (MIC) of ampicillin and kanamycin. Furthermore, we used a series of serial dilutions to demonstrate that, not only does growth impact MIC, but MIC is intrinsically tied to initial bacterial density. Overall, our results suggest that manipulating the growth rate of P. aeruginosacan influence its ability to be killed by antibiotics.