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Document Type |
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Thesis |
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Document Title |
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PHENOTYPIC AND MOLECULAR CHARACTERIZATION OF ACINETOBACTER BAUMANNII CLINICAL ISOLATES FROM SAUDI ARABIA. التوصيف الظاهري والجزيئي لعزلات سريرية لراكدة بومانية من المملكة العربية السعودية |
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Subject |
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Faculty of Applied Medical Sciences |
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Document Language |
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Arabic |
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Abstract |
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Multidrug-resistant Acinetobacter baumannii has emerged as one of the most troublesome pathogens for healthcare institutions worldwide. However, limited information is collected on the antimicrobial resistance rates among clinical isolates in Saudi Arabia. Here we aim to characterize a nationally representative collection of isolates.
Isolates (n=200) were collected between March-2018 and March-2019 from five National Guard-Health Affairs hospitals covering the eastern, western and central regions of Saudi Arabia. Identification and antimicrobial susceptibility testing (AST) were determined using VITEK II system. In addition, the identification and AST were confirmed using PCR-based methods. Mechanisms of resistance were also identified using PCR-based methods.
A subset of isolates (n=120) was further characterized by multi-locus sequence typing (MLST) (n=77) using the Oxford scheme or by whole genome sequencing (n=43) on the MiSeq instrument. The Phylogeny was defined by single nucleotide polymorphism (SNP) analysis.
Majority (61%) of the isolates were resistant to carbapenems among which most (96.8%) encoded oxacillinase )OXA(-23-like; the remaining produced OXA-24-like. Isolates were variably resistant to gentamicin (36.5%) and tobramycin (42.4%) but remained mostly susceptible to colistin (93.7%) and tigecycline (78.8%). MLST and genome sequences identified 44 different sequence types (ST) among carbapenem-resistant (n=90) and -sensitive (n=24) isolates. STs of carbapenem-sensitive isolates were highly diverse whereas most (88.9%) of resistant isolates were single or double locus variants of each other and comprised ST557 (n=25), ST218 (n=23), ST195 (n=13), ST1286 (n=8), ST451 (n=4), ST208 (n=2), ST444 (n=2), ST214 (n=1) and ST1050 (n=1), all of which belonged to ST2 (Pasteur scheme). Overall, phylogenetic analysis clustered carbapenem-resistant ST2 isolates according to their Oxford STs, but these were hundreds of SNPs apart. Among most common STs, SNP analysis identified close relatedness between collected isolates suggesting inter- and intra-hospital transmission.
Our results showed a high prevalence rate of carbapenem resistance among A. baumannii in Saudi Arabia that was mainly associated with the acquisition of OXA-23-like carbapenemase. Majority of carbapenem-resistant isolates belonged to ST2 (Pasteur scheme), but these were highly diverse at the whole-genome level. |
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Supervisor |
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Dr. Turki Abu Jamel |
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Thesis Type |
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Master Thesis |
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Publishing Year |
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1441 AH
2020 AD |
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Added Date |
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Tuesday, July 28, 2020 |
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Researchers
| ريما علي باوزير | Bawazeer, Rima Ali | Researcher | Master | |
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