النشاط المضاد للغشاء الحيوي للميلتين المشتق من سم النحل ضد انواع بكتريا الراكدة : تثبيط تكوين الغشاء الحيوي و التعبير الجيني المرتبط به

Anti-Biofilm Activity of Bee Venom-Derived Melittin Against Acinetobacter spp : Suppression of Biofilm Formation and Related Gene Expression

The increasing antibiotic resistance to Acinetobacter spp, is more sophisticated problem in public health. Collected two hundred clinical specimens from various sources from patient who admitted to Imam Hussein Medical City, the study beginning from January 2024 till August 2024. The specimens with risk factor group which included sputum, wound, urine, blood and fluid and all specimens were collected as 40 positive cases.
Melittin was extracted from honey bee venom samples (Apis mellifera carnica) ,Venom samples were collection during March of 2024 in Al-Kut and Kerbala governorate (Iraq) and evaluated from local bee venom via High-Performance Liquid Chromatography (HPLC) and detection of the standard compound and the isolated compound was performed, along with Fourier transform infrared spectroscopy (FTIR) spectrum analysis.
Detection of biofilm formation before and after melittin treatment by quantitative assay via Micro-titer plate method was divided into three groups(strong biofilm, moderate biofilm and weak biofilm). Also done estimating the effectiveness of melittin extract through genetic expression of the Bap, AbaR, adaRS genes by using qRT-PCR.
The collection specimens from patients included 40(20%) positive specimens distributed as 25 (62%) from females, and 15 (38%) from males and the highest infection percentage was in sputum specimens reaching 17(42.5%). After cultured on Blood and MacConkey agar, the isolates were identified via VITIK 2 compact system. All isolates were tested for their resistance to 18 different antibiotics and the results exhibited that highest level of resistance in Acinetobacter spp isolates to total antibiotics used in this study except Colistin, Minocycline and Tigecycline were sensitive in the rate36 (90%), 35 (87.5)and 30(75%) respectively.
After melittin treatment the absorbance value for strong biofilm formation decreased to 52%, absorbance value for moderate biofilm formation was reduced to %55 indicating a substantial decrease in biofilm density and absorbance value for weak biofilm formation was recorded 24% showing a slight reduction compared to the pre-treatment measurements.
The present study included the gene expression of the three genes responsible for bacterial virulence before and after the addition of melittin and the study investigated the impact of melittin, a bee venom component, on Acinetobacter spp biofilm formation and Bap ,AbaR, adaRS genes expression, there was a significant reductions were observed post-treatment.
In strong biofilms Bap gene folding dropped from 28.04 ± 4.67 to 6.37 ± 1.73 , and on moderate biofilms showed declining gene folding declining from 10.05 ± 2.86 to 4.28 ± 0.93, while the weak biofilms exhibited reductions in gene folding 7.91 ± 1.53 to 2.03 ± 0.13. These results suggest melittin inhibits biofilm formation by down regulating Bap gene expression. Similarly adeRS gene expression, strong biofilms declined from 16.83 ± 4.56 to 5.92 ± 1.02, moderate from 12.42± 3.16 to 4.68± 1.33, and weak from 6.84± 2.71 to 2.08 ± 0.94, post-treatment. For, abaR gene expression decreased in strong biofilms from 20.27 ± 5.73 to 8.34 ± 1.82 and in moderate biofilms from 15.03 ± 3.37 to 6.50 ± 1.19, while weak biofilms decreased from 11.46 ± 2.48 to 3.58 ± 0.85. indicating melittin’s effectiveness against both biofilm formation and gene expression.
The study concluded that the most common cases of infection with Acinetobacter spp bacteria in sputum, and that this bacteria has a high resistance to most antibiotics. Melittin has an actual effect to inhibitors bacteria growth.