Effect of Sub-Inhibitory Concentrations of Ciprofloxacin, Curcumin, and Capsaicin on Quorum Sensing Gene Expression in Acinetobacter Baumannii Isolates

Abstract

Acinetobacter baumannii is a common Gram –negative, non-fermenting coccobacillus. Bacteria can live in blood, urine, skin, soft tissues, lungs, digestive tract, wounds, and brain. Form a biofilm and efflux pumps and is quite resistant to several drugs. The study proposed to consider the A. baumanni prevalence in different infections, to determine the MIC of ciprofloxacin, use molecular methods (PCR) to find genes, effect of ciprofloxacin, curcumin, and Capsaicin on Ggene expression of Quorum Sensing (QS). From October 8, 2025, to January 1, 2026, 160 l specimens were taken from different infections at Iraq's Baqubah Teaching Hospital.

The results showed that 20 of the isolates (12.5% of the total) had a positive growth rate for A. baumannii. The samples were sorted by where they came from: wounds, sputum, burns, and urine were 15%, 45%, 30%, 10% respectively. The study found the fold change values following treatment with ciprofloxacin, curcumin, and capsaicin, for the abaI gene were 0.7239, 0.0236, and 0.1453, respectively, while the change for abaR gene was 0.7100, 0.0122, and 0.3927, respectively. The effect of sub-MIC combination of ciprofloxacin with curcumin was more than with capsaicin, where the fold change values were recorded 0.0528 and 1.6353, respectively for abaI, while 0.0729   and 2.0507 for abaR gene.

The conclusion of this study is that the fold change value of quorum sensing abaI, abaR genes significantly changed, and after treatment with ciprofloxacin, curcumin, and capsaicin, in addition, the significant effect of ciprofloxacin and curcumin mixture gives promising ideas for suggesting alternative strategies to lowering the virulence factors controlled by QS, such as biofilm formation to resolve the antibiotics resistance problem for A . Baumannii isolates