No abstract

Purpose Rising Antibiotic Resistance has put the world in real threat. Methicillin resistant Staphylococcus aureus (MRSA), is a predominant cause of suppurative chronic skin and soft-tissue infections. Novel insights have focused the light on plant extracts. In this study, Ruta graveolens ethanolic active extract was tested for its potential anti-virulence activities in MRSA. Materials and Methods A total of 100 MRSA strains causing skin and soft tissue infections were isolated and antibiotic susceptibility testing was done. Ability to form biofilm was tested phenotypically. Furthermore, the antimicrobial activity of Ruta graveolens was evaluated followed by detection of its Minimum inhibitory concentration (MIC). The inhibitory activity of this extract on biofilm formation was investigated. Afterwards, we investigated its effect on the transcription of biofilm-related genes and mecA gene. Results All tested isolates were sensitive to Vancomycin and Linezolid while high resistance was noted with both Fusidic acid (83%) and Gentamicin (68%). (83%) of the isolates were biofilm producers. Ruta graveolens extract showed strong antimicrobial activity against the MRSA strains with MIC 0.78 mg/mL. At subinhibitory concentration (1/2 MIC), the extract had high biofilm inhibitory effects with mean inhibition (70%). Moreover, transcriptional analysis results showed that the mean percentages of inhibition in expression of mecA, icaA and icaD genes were 52.3%, 34.8% and 33.7%, respectively, in which all showed statistically significant difference ( p ≤ 0.05). Conclusion The current study proposes the ability of Ruta graveolens extract to reduce the biofilm formation and antibiotic resistance of MRSA through downregulation of some biofilm forming genes and mecA gene which confers resistance to B-lactam antibiotics. This may decrease our reliance on antibiotics and improve our ability to effectively treat biofilm-related skin and soft-tissue infections caused by MRSA.

Background: Klebsiella pneumoniae (K. pneumoniae) is a significant contributor to nosocomial infections in neonates and children. This is due to a variety of virulence mechanisms, such as the ability to form biofilms and antibiotic resistance. Hence, this study aimed to evaluate the prevalence of K. pneumoniae infections among children, to determine the association of their antimicrobial resistance patterns, biofilm formation ability, and their molecular genotypes. Methods: Forty-six K. pneumoniae isolates were collected from a pediatric hospital in Alexandria, Egypt. After being identified by conventional methods, they were tested for their susceptibility to different classes of antibiotics, biofilm formation ability, and were genotyped by enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR). Results: Klebsiella pneumoniae was the most prevalent bacteria isolated from children (36%). Antimicrobial susceptibility testing revealed that the majority of our isolates (47.8%) were extensively drug-resistant (XDR) and 41.3 % were multi-drug resistant (MDR). Among the isolates, 80.4% were biofilm producers. No statistically significant association was noticed between the biofilm-producing ability and the drug-resistance type. Based on ERIC-PCR profile results, isolates were classified into 3 main clusters and 30 different ERIC genotypes. Moreover, no statistically significant association was found between ERIC-PCR clusters and neither the ability to produce biofilm nor the drugresistance type. Conclusions: The results of this study indicate an alarming increase in the antimicrobial resistance patterns among K. pneumoniae isolated from neonates and children. ERIC-PCR typing showed high