Screening honey for antibacterial activity against acinetobacter baumannii

Juraybi, Tawfiq 2023. Screening honey for antibacterial activity against acinetobacter baumannii. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Acinetobacter baumannii is a frequent cause of infections in hospitals around the world which are difficult to treat due to there inherent antibiotic resistance. It is particularly prevalent in intensive care units (ICUs) and around 19.5% of A. baumannii infections in the UK resulted in bacteraemia (mostly in infants and the elderly) in 2020. Due to the challenge in treating infections caused by this bacteria, there is considerable interest in exploring natural products for compounds with novel antimicrobial activity. Honey has been used for many centuries in traditional medicines to treat infections. In addition to its antibacterial activity honey possesses anti-oxidant and anti-inflammatory properties. The aim of this project is to screen our collection of 277 honey samples collected from across Wales for the presence of antibacterial compounds with activity against clinical isolates of A. baumannii with a particular focus on isolates resistant to multiple antibiotics. A total of 46 clinical isolates provided by Public Health Wales were characterised using a combination of phenotypic (biochemical, antibiotic and honey sensitivity testing) and genotypic (BlaOXA-51) methods. Using these approaches 35 isolates were identified as A. baumannii. Of this total 12 isolates were resistant to all of the antibiotics (Imipenem, Meropenem, Ciprofloxacin, Levofloxacin, Amikacin, Gentamicin, Netilmicin, Tobramycin) commonly used in hospitals to treat infections caused by this organism while a further 10 isolates were resistant to at least 3 of those antibiotics. To further characterise these isolates they were screened for the presence of additional A. baumannii specific genetic markers (BlaOXA-23 and Class 1 integrase (Int1)). Four different genotypes were identified: BlaOXA-51 positive22 (62.8%), BlaOXA-51 and BlaOXA-23 positive 11 (31.4%), BlaOXA-51, BlaOXA-23 and Int1 positive 1 (2.9%) and BlaOXA-51 and Int1 positive 1 (2.9%). To provide a group of A. baumannii isolates representative of the diversity of the species and which included antibiotic resistant and sensitive examples we assembled a panel of two control organisms and six clinical isolates. The 277 honey samples in our collection were first screened for antimicrobial activity against our control organisms, A. baumannii ATCC 19568 (antibiotic sensitive), OXA-23 clone 1 and OXA-23 clone 2 (antibiotic resistant isolates) using an agar well diffusion assay. Interestingly, we saw significant difference in the honey sensitivity of the antibiotic sensitive and resistant isolates. The 15 most active honey samples identified from this screen were selected for activity testing against our panel of genetically diverse, antibiotic resistant isolates of A. baumannii.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Pharmacy
Subjects:	Q Science > Q Science (General)
Date of First Compliant Deposit:	20 March 2024
Last Modified:	20 Mar 2024 13:05
URI:	https://orca.cardiff.ac.uk/id/eprint/167351

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