The emergence of multidrug-resistant (MDR) strains is a major health problem worldwide. There is an urgent need for novel strategies to combat bacterial infections caused by MDR strains like Pseudomonas aeruginosa and Acinetobacter baumannii. Quorum sensing (QS) is a critical communication system in bacterial community controlling survival and virulence. The awareness of the importance of QS in bacterial infections has stimulated research to identify QS inhibitors (QSIs) to defeat microbes. In this study, four FDA-approved drugs (besides azithromycin as positive QSI) were tested for potential QS inhibition against clinical A. baumannii isolates and P. aeruginosa (PAO1) standard strain. The inhibitory effect of these drugs on virulence factors of both microbes has been investigated. The studied virulence factors include biofilm formation, twitching and swarming motilities, proteolytic enzyme production, and resistance to oxidative stress. The four tested drugs (erythromycin, levamisole, chloroquine, and propranolol) inhibited QS in Chromobacterium violaceum by 84, 72, 55.1, and 37.3%, respectively. They also significantly inhibited virulence factors in both PAO1 and A. baumannii at sub-inhibitory concentrations. These findings were confirmed by qRT-PCR and mice mortality test, where tested drugs highly repressed the expression of abaI gene and showed significantly improved mice survival rates. In addition, molecular docking studies against AbaI and AbaR proteins of QS system in A. baumannii revealed the potential inhibition of QS by tested drugs. Beside their known activities, the tested drugs could be given new life as QSIs to combat A. baumannii nosocomial infections (alone or in combination with antimicrobials).

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A series of study aimed to improve egg production, egg quality and immunity resulted by cross-breeding with Arab chickens and laying chickens has been observed on 400 chickens of 5-month old of hens was used and treatment was divided into 2 groups: medium and heavy type hens. Randomized Block Design was used and hens were fed on a laying diet contained 18% of crude protein content and 2900 kcal/kg of metabolism energy. Parameters observed were the number of daily eggs (hen/day), clutch, egg weight, egg shape, shell thickness, Haugh unit (HU) and the total percentage of egg production during one production cycle. Immunity was observed by thymus size and time of thymus regression. The results showed that daily and total egg production, clutch spacing, egg weight, egg shape, hemp thickness, Haugh unit (HU) of egg in both heavy and medium type were significantly higher than pure local chicken. However, all the parameters of egg production and egg quality on the type of weight were significantly higher than the light type. In terms of immunity, time of thymus regression on crossbreed hen type occurred at 14-16 weeks of age. It concluded that crossbreeding between local chicken increased egg production and egg quality on derivatives of local chicken. It was also informed that the immunity of derivatives of local chicken resulted by crossbreeding against endemic diseases was better than that of in natural breed chicken.