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Title: Evolution of carbapenem-resistant Acinetobacter baumannii in immuno-compromised patients with diabetes mellitus in Eastern Saudi Arabian hospitals
Author: Alsultan, A. A.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2009
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The prevalence of carbapenem resistance was investigated in A. baumannii strains isolated from diabetic patients in Saudi Arabia. 32% were resistant to imipenem (MIC 16-64 mg/L) and meropenem (MIC 4-64 mg/L). However, all isolates were sensitive to colistin and tigecycline. All isolates were highly resistant (MIC >128mg/L) to all remaining antimicrobial agents used in this study. Eleven imipenem-resistant isolates (MIC 16 – 64 mg/L) possessed the insertion sequence ISAba1; six of them possess blaOXA-23 gene, and four also had ISAba2. One isolate (MIC 16mg/L) had blaOXA-40 and ISAba1 and one imipenem-sensitive isolate (MIC 0.25mg/L) harboured ISAba2, ISAba3 and IS18. Twenty-three (61%) of both imipenem-sensitive and resistant isolates had ISAba1 whereas 28 (74%) clinical isolates had blaampC. All imipenem-resistant isolates were positive with amplification of the blaVIM gene by PCR and this was confirmed by sequencing where the gene was confirmed as blaVIM-2. Ten strains possessed four novel blaOXA-51-like genes encoding ß–lactamases deposited in the GenBank nucleotide database under accession numbers: EU547443(OXA-90), EU547445 (OXA-130), EU547446 (OXA-131) and EU547447 (OXA-132). The multi-drug-resistance A. baumannii (MdRAB) strains from the diabetic patients showed the highest and broadest growth capabilities, multiplying equally well at critically high glucose levels as well as at low levels. That was in direct comparison with seven control strains, A. baumannii from non diabetics. A. baumannii sensitive strain, MRSA-15, MRSA-16, S. aureus, P. aeruginosa and E. coli. These results suggest that MdRAB has the ability not only to grow successfully in the presence of glucose but also to maintain this capability at all concentrations found within the fluctuating levels of diabetic patients. This suggests the condition of diabetes may preferentially select MdRAB over sensitive strains and also over other multiresistant pathogens. The blaOXA-23 genes were more frequent (16%) than blaOXA-40 (2.6%) and no blaOXA-58 were identified. All blaOXA-23 strains also harboured blaVIM-2 enzymes.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available