Efficacy of Some Antibiotics and Essential Oils Against Acinetobacter baumannii: An in Vitro Study

Abstract

Background Acinetobacter baumannii (A. baumannii) is a bacterium that is classified as opportunistic pathogens in hospitals, especially in immunocompromised patients and children. Regarding their role as pathogens, some studies in the last two decades have shown their involvement in many human infections, especially in intensive care units (1,2). A. baumannii colonizes the skin and upper respiratory tracts. It is isolated from urine, sputum, blood, and feces. In addition, it is usually found in hospitals on different surfaces. In other words, they are isolated from different locations within the hospitals (e.g., air, water faucets, bedsides, gloves, and catheters). Historically, this type of infection is associated with war-wounded due to the direct contamination of wounds in the surrounding environment. For example, it was the most isolated Gramnegative bacterium from the wounds of those wounded in the Vietnam War, as well as the case with those wounded in the US war in Iraq. Recent reports indicate an increased incidence of septicemia in military hospital patients (2). A. baumannii exhibits high resistance against most antibiotic groups because it owns genes that encode inhibitory enzymes (3). For example, carbapenemresistant A. baumannii strains show high resistance to most antibiotics, particularly beta-lactamase groups (4), because these strains own bla OXA-51-like and bla OXA-23-like genes which encode enzymes that inhibit the action of these antibiotics (5). Further, other studies demonstrated that most clinical isolates of A. baumannii were resistant to most cephalosporins (6), and this bacterium was also completely resistant to aztreonam, cefotaxime in addition to amoxicillin-clavulanic acid combination (7). Essential oils and plant extracts are used as new sources of antibacterial and antimicrobial agents in many fields (8), which include food preservation (9), pharmaceuticals, alternative medicine, and natural treatments (10-11). Furthermore, many plant extracts and oils are commonly used as medicinal plants in Syria for several purposes, especially for respiratory and gastrointestinal disorders. Considering the above-mentioned explanations, this study aimed to conduct a survey on the antibacterial activity of several antibiotics and essential oils, in vitro, against the isolates of A. baumannii obtained from children. Materials and Methods Identification of Bacteria Two hundred and one samples were collected from Children's Hospital of Damascus, Damascus, Syria from different sources (e.g., skin abscesses, bronchial secretions, urine, pharyngeal smears, and blood) during