African Journal of

  • Abbreviation: Afr. J. Biotechnol.
  • Language: English
  • ISSN: 1684-5315
  • DOI: 10.5897/AJB
  • Start Year: 2002
  • Published Articles: 12172

Full Length Research Paper

Genetic basis of carbapenem resistance in Acinetobacter clinical isolates in Saudi Arabia

Abdullah A. Al-Arfaj1, Abdelnasser S.S. Ibrahim2*, Ali Mohammed Somily3 and Ali A. Al-Salamah2
1Department of Medical laboratory, College of Health Science, King Saud University, Riyadh 11416, Kingdom of Saudi Arabia. 2Department of Botany and Microbiology, College of Science, King Saud University, P.O. 2455 Riyadh 11351, Kingdom of Saudi Arabia. 3Department of Pathology, College of Medicine, King Saud University, Riyadh 1146,Saudi Arabia.
Email: [email protected]

  •  Accepted: 12 October 2011
  •  Published: 26 October 2011


Carbapenem-hydrolyzing oxacillinases are reported increasingly in Acinetobacter baumannii. Here we report the contribution of carbapenem-hydrolyzing oxacillinases genes to carbapenem resistance in clinical Acinetobacter baumannii strains in Saudi Arabia. Forty non-repetitive clinical A. baumannii strains were isolated and identified from 40 patients, hospitalized in various wards in King Khalid University and Armed Forces Hospitals (Riyadh, Saudi Arabia). Antibiotic susceptibility testing indicated that most isolates (65 to 100% of the total strains) were resistant to β-lactams antibiotics with minimum inhibitory concentrations (MICs) ranged from low to very high values. In addition, 65 and 67.5% of the total isolated clinical strains were resistant to carbapenem antibiotics, including imipenem and meropenem, respectively. Based on antibiotic susceptibility, it was possible to divide the isolated clinical A. baumannii strains into four phenotypes clusters, I, II, III and IV, with multiple antibiotic resistance of > 90% (with very high MICs), 80 to 89% (with high MICs), 70 to 79% (with moderate MICs), and 40 to 69 (with moderate to low MICs), of the total antibiotics (n = 17), respectively. The results of polymerase chain reaction (PCR) products analysis reveals that the major groups of oxacillinases genes including blaOXA-23blaOXA-24, and blaOXA-58 were detected in 72.5% (n = 29), 45% (n = 18) and 37.5% (n = 15) of the isolated Abaumannii strains, respectively. In addition, analysis of the prevalence of different oxacillinases genes in different antibiotics-based phenotypes clusters, revealed that cluster I harbored the highest distribution of resistant genes, which could explain the extremely multiple antibiotic resistance phenotype within the strains of this cluster.


Key words: Acinetobacter baumannii, oxacillinases, multi drug resistance, β-lactam.


MICS, Minimum inhibitory concentrations; PCRpolymerase chain reaction; ICUs, Intensive Care Units; MDR, multidrug resistant; CHDLs,carbapenem-hydrolyzing oxacillinases; CLSI, Clinical and Laboratory Standard Institute.

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