Genetic diversity of OXA-51-like genes among multidrug-resistant Acinetobacter baumannii in Riyadh, Saudi Arabia

European Journal of Clinical Microbiology (Impact Factor: 2.54). 02/2014; 33(7). DOI: 10.1007/s10096-014-2068-0
Source: PubMed

ABSTRACT We explore the genetic diversity of class D oxacillinases, including OXA-23, -24 (-40), -58 and, particularly, the intrinsic OXA-51-like genes, among multidrug-resistant (MDR) Acinetobacter baumannii strains from inpatients at a tertiary care hospital in Riyadh, Saudi Arabia. Sequence-based typing (SBT) of the OXA-51-like gene was carried out on 253 isolates. Selected isolates (n = 66) were subjected to multilocus sequence typing (MLST). The polymerase chain reaction (PCR) typing results showed that all isolates (n = 253) contained the OXA-51-like and OXA-23 genes. However, the OXA-58 gene was detected in five isolates. Further, none of the isolates had the OXA-40 (identical to the OXA-24) gene. SBT revealed a high OXA-51-like genotypic diversity and showed that all isolates were clustered into four main groups: OXA-66 (62.3 %), followed by OXA-69 (19.1 %), OXA-132 (7.6 %) and other OXA-51-like genes (10.3 %), including OXA-79, -82, -92, -131 and -197. MLST revealed four main sequence types (STs), 2, 19, 20 and 25, among the isolates, in addition to six isolates with newly designated ST194-ST197 singletons. Further, a high prevalence (81.4 %) of OXA-66 and OXA-69-like genes in A. baumannii was identified. More studies are essential in order to explore the molecular mechanisms that confer carbapenem-resistant phenotypes for A. baumannii isolates and to investigate the genetic diversity of other OXA-D genes.

  • [Show abstract] [Hide abstract]
    ABSTRACT: We investigated the distribution of resistance genes and the clonal relationships among carbapenem-resistant Acinetobacter baumannii isolates from the intensive care unit wards of two hospitals in Guangzhou, China. From 2012 to 2013, 57 A. baumannii isolates were obtained from blood cultures from two hospitals in Guangzhou. The antibiotic resistance profiles were determined by using the Vitek2 system and Etest strips. PCR was used to detect the genes encoding OXA-type carbapenemases and metallo-β-lactamases and the presence of ISAba1 upstream of the blaOXA-51-like gene and the blaOXA-23-like gene. Multilocus sequence typing (MLST) and sequence-based typing of blaOXA-51-like genes (SBT-blaOXA-51-like genes) were performed to analyze the genetic relationship of the isolates. Among the 57 isolates, 46 were carbapenem-resistant A. baumannii (CRAB) isolates. The blaOXA-51-like gene was identified in all 57 isolates, while the blaOXA-23-like gene was present in all 46 CRAB isolates. The MLST analysis grouped the A. baumannii isolates into five existing sequence types (STs) and five new STs. Fifty-two isolates belonged to the worldwide spread of clonal complex 92 (CC92), among which ST195 and ST365 were the most common STs. The MLST data and SBT-blaOXA-51-like genes showed that all isolates harboring the major blaOXA-51-like alleles, such as blaOXA-66, belonged to CC92.
    Microbial drug resistance (Larchmont, N.Y.) 01/2015; DOI:10.1089/mdr.2014.0183 · 2.52 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A. baumannii has emerged as an important nosocomial pathogen with an outstanding ability to acquire multidrug resistant mechanisms. In this study, we investigate the molecular epidemiology and carbapenem resistance mechanisms of A. baumannii in Tripoli, Northern Lebanon. One hundred sixteen non-duplicate isolates isolated between 2011 and 2013 in different hospitals in Tripoli, Lebanon from Lebanese patients and wounded Syrian patients during Syrian war were studied. Antibiotic susceptibility testing was determined by agar disc diffusion and Etest. Carbapenemase-encoding genes were investigated by PCR. All isolates were typed by bla OXA-51-like sequence based typing (SBT) and 57 isolates were also analysed by MLST using Pasteur's scheme followed by eBURST analysis. Of the 116 isolates, 70 (60 %) showed a carbapenem resistance phenotype. The bla OXA-23 with an upstream insertion of ISAba1 was the major carbapenem resistance mechanism and detected in 65 isolates. Five isolates, including four from wounded Syrian patients and one from a Lebanese patient, were positive for bla NDM-1. bla OXA-51-like SBT revealed the presence of 14 variants, where bla OXA-66 was the most common and present in 73 isolates, followed by bla OXA-69 in 20 isolates. MLST analysis identified 17 sequence types (ST) and showed a concordance with bla OXA-51-like SBT. Each clonal complex (CC) had a specific bla OXA-51-like sequence such as CC2, which harboured bla OXA-66 variant, and CC1 harbouring bla OXA-69 variant. NDM-1 producing isolates belonged to ST85 (4 Syrian isolates) and ST25 (1 Lebanese isolate). Our results showed a successful predominance of international clone 2 with a widespread occurrence of OXA-23 carbapenemase in Lebanese hospitals. These findings emphasise the urgent need of effective measures to control the spread of A. baumannii in this country.
    BMC Microbiology 05/2015; 15(1):103. DOI:10.1186/s12866-015-0441-5 · 2.98 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The molecular epidemiology and mechanisms of resistance of carbapenem-resistant Acinetobacter baumannii (CRAB) were determined in hospitals in the countries of the Gulf Cooperation Council (GCC), namely, Saudi Arabia, United Arab Emirates, Oman, Qatar, Bahrain, and Kuwait. Isolates were subjected to PCR-based detection of antibiotic-resistance genes and repetitive sequence-based PCR (rep-PCR) assessments of clonality. Selected isolates were subjected to multilocus sequence typing (MLST). 117 isolates found resistant to carbapenem antibiotics (either imipenem or meropenem) were investigated. All isolates were positive for OXA-51. The most common carbapenemases were of the OXA-23-type in 107 isolates followed by OXA-40-type (OXA-24-type) in 5 isolates; 3 isolates were found to carry the ISAba1 element upstream of blaOXA-51-type. No OXA-58-type, NDM-type, VIM-type, or IMP-type producers were detected. Multiple clones were detected with 16 clusters of clonally related CRAB. Some clusters involved hospitals in different countries. MLST analysis of 15 representative isolates from different clusters identified seven different sequence types; ST195, ST208, ST229, ST436, ST450, ST452 and ST499, as well as three novel STs. The vast majority of the isolates in this study (84%) were associated with healthcare exposure. Awareness of multidrug resistant organisms in GCC countries has important implications for optimizing infection control practices, establishing antimicrobial stewardship programs within hospital, community, and agricultural settings, and reemphasizing the need for establishing regional active surveillance systems. This will help to control the spread of CRAB in the Middle East and in hospitals accommodating transferred patients from this region. Copyright © 2015, American Society for Microbiology. All Rights Reserved.
    Journal of Clinical Microbiology 01/2015; 53(3). DOI:10.1128/JCM.02784-14 · 4.23 Impact Factor