ABSTRACT
Objective: To observe the effect of the (p)ppGpp synthase gene (relA) on the heteroresistance of colistin against Acinetobacter baumannii. Methods: The relA gene in Acinetobacter baumannii ATCC19606 was knocked out by Red homologous recombination technique. The biofilm formation of Acinetobacter baumannii was observed by crystal violet staining. The change of heterogeneous colonies of Acinetobacter baumannii under the action of colistin was detected by population analysis profiles (PAP) and the heterogeneity was calculated. The killing curve was used to detect the formation of persistent bacteria in Acinetobacter baumannii under the action of colistin. Results: The relA gene in Acinetobacter baumannii was successfully knocked out, and the relA knockout strain ATCC19606-ΔrelA was obtained. After relA gene knockout, the biofilm formation of Acinetobacter baumannii decreased significantly. After relA gene knockout, Acinetobacter baumannii significantly reduced the heterogeneous colonies and persistent bacteria formation under the action of colistin. Conclusion: The bacterial stringent reaction (p) ppGpp synthase relA may be an important factor affecting the heteroresistance of Acinetobacter baumannii to colistin.