Molecular effects of silver nanoparticles on virulence factors in acinetobacter Baumannii isolated from diyala province, Iraq

Acinetobacter baumannii is a Gram-negative bacterium that has been linked to an increasing number of illnesses and outbreaks in hospitals. The continuous emergence of strains resistant to various drugs makes it difficult to effectively prevent and manage these diseases. At least 33 different Acinetobacter genotypes have been identified using molecular techniques, especially DNA-DNA hybridization. The aim of this study was to isolate A. baumannii from different clinical samples and to investigate the effect of silver nanoparticles on the expression level of virulence genes. A total of 175 clinical specimens were obtained from individuals of various ages and genders who were hospitalized or treated as outpatients for wounds and burns at Baquba Teaching Hospital and Al-Batoul Teaching Hospital in Diyala Province, Iraq. All bacterial isolates of A. baumannii were characterized using morphological, microscopic, biochemical tests and VITEK-2 method. Identification of A. baumannii was carried out using bacteriological methods including microscopic analysis including examination of colony morphology on blood agar, including shape and color, as well as Gram staining to assess cell morphology, arrangement and type of reaction to stain. Molecular analysis including DNA sequencing and expression of virulence genes was performed using RT-PCR method. The results revealed that Acenitobacter baumanni isolates were identified using morphological, microscopic, biochemical tests and VITEK-2 method. The BlaOXA-51-like carbapenemase gene can be identified by PCR as a simple and effective molecular tool to identify A. baumannii isolates. A. baumannii isolates produce β-lactamases, including ESBLs and CHDLs such as OXA-23, OXA-24 and OXA-58. Most A. baumannii isolates are resistant to routinely administered antibiotics, including Ceftazidime, Ceftriaxone, Cefepime (cephalosporins), Ampicillin-sulbactam, Tigecycline and Amikacin. The results showed that all A. baumannii isolates were susceptible to Tobramycin and Trimethoprim/Sulfamethoxazole before and after AgNP treatment. The findings demonstrated that all isolates of A. baumannii were sensitive to Tobramycin and Trimethoprim/Sulfamethoxazole before and after AgNP treatment. Our findings demonstrated that AgNPs treatment was effective in inhibiting biofilms produced by various microorganisms and eradicating MDR A. baumannii strains, as well as revealing a clear effect of silver nanoparticles on the mechanism of antibiotic action on these multi-drug resistant pathogenic bacteria. It can be concluded from the current study that treatment of A. baumannii with Ag nanoparticles was shown to be effective. Most A. baumannii isolates were resistant to routinely administered antibiotics. All isolates of A. baumannii were sensitive to Tobramycin and Trimethoprim/Sulfamethoxazole before and after AgNP treatment. There are mounting evidence that A. baumannii has blaOXA-51 like gene, which is naturally occurring gene intrinsically present in this species only.