Ranko Ladavac1, Branka Bedenić2, Mirna Vranić-Ladavac3, Nada Barišić3, Natalie Karčić3, Karoline Pompe4, Antun Ferenčić5, Aleksandar Stojanović3, Harald Seifert6, Stjepan Katić7, Paul G Higgins6. 1. Department for Nephrology, General Hospital Pula, Pula, Croatia. 2. Department for Microbiology, School of Medicine, University of Zagreb, Zagreb, Croatia; Clinical Department for Clinical and Molecular Microbiology, University Hospital Center Zagreb, Zagreb, Croatia. Electronic address: branka.bedenic@kbc-zagreb.hr. 3. Department for Microbiology, Public Health Institute of Istria County, Pula, Croatia. 4. Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Goldenfelsstrasse 19-21, Cologne, Germany. 5. School of Medicin, University of Rijeka, Rijeka, Croatia. 6. Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Goldenfelsstrasse 19-21, Cologne, Germany; German Centre for Infection Research (DZIF), Partner Site Bonn-Cologne, Cologne, Germany. 7. Clinical Department for Clinical and Molecular Microbiology, University Hospital Center Zagreb, Zagreb, Croatia.
Abstract
OBJECTIVES: During routine diagnostic laboratory work, the clinical microbiologist observed an increase of Acinetobacter baumannii isolates with three different carbapenem susceptibility patterns: susceptible, intermediate and resistant. Isolates belonging to the same carbapenem susceptibility phenotype exhibited identical susceptibility/resistance patterns to non-β-lactam antibiotics. This prompted us to analyse the mechanisms of carbapenem-resistance and the molecular epidemiology of the isolates. A total of 59 A. baumannii isolates were analysed and grouped according to their susceptibility to imipenem: group 1 were susceptible (N=24), group 2 were intermediate (N=8) and group 3 were resistant (N=27) to imipenem. MATERIAL AND METHODS: PCR and sequencing was used to detect resistance genes. Genotyping of the isolates was performed by PFGE and MLST. RESULTS: Out of 27 resistant isolates, 20 harboured blaOXA-40-like and 7 blaOXA-23-like genes. ISAba1 was found upstream of blaOXA-51 and blaOXA-23 genes. PFGE genotyping demonstrated the existence of three major A. baumannii clones in GH Pula and determination of sequence groups showed that the isolates belonged to international clones commonly associated with multidrug-resistance. MLST (performed on six isolates) showed diverse population structure of isolates belonging to the same cluster, including ST 195, ST 231, ST 775 and ST 1095. CONCLUSIONS: A previous study conducted in 2009-2010 showed that reduced susceptibility to carbapenems in GH Pula was only associated with upregulation of the intrinsic OXA-51 β-lactamase. In this study a shift to isolates with acquired oxacillinases, belonging to two major clones was reported.
OBJECTIVES: During routine diagnostic laboratory work, the clinical microbiologist observed an increase of Acinetobacter baumannii isolates with three different carbapenem susceptibility patterns: susceptible, intermediate and resistant. Isolates belonging to the same carbapenem susceptibility phenotype exhibited identical susceptibility/resistance patterns to non-β-lactam antibiotics. This prompted us to analyse the mechanisms of carbapenem-resistance and the molecular epidemiology of the isolates. A total of 59 A. baumannii isolates were analysed and grouped according to their susceptibility to imipenem: group 1 were susceptible (N=24), group 2 were intermediate (N=8) and group 3 were resistant (N=27) to imipenem. MATERIAL AND METHODS: PCR and sequencing was used to detect resistance genes. Genotyping of the isolates was performed by PFGE and MLST. RESULTS: Out of 27 resistant isolates, 20 harboured blaOXA-40-like and 7 blaOXA-23-like genes. ISAba1 was found upstream of blaOXA-51 and blaOXA-23 genes. PFGE genotyping demonstrated the existence of three major A. baumannii clones in GH Pula and determination of sequence groups showed that the isolates belonged to international clones commonly associated with multidrug-resistance. MLST (performed on six isolates) showed diverse population structure of isolates belonging to the same cluster, including ST 195, ST 231, ST 775 and ST 1095. CONCLUSIONS: A previous study conducted in 2009-2010 showed that reduced susceptibility to carbapenems in GH Pula was only associated with upregulation of the intrinsic OXA-51 β-lactamase. In this study a shift to isolates with acquired oxacillinases, belonging to two major clones was reported.
Authors: Andrea J Grisold; Josefa Luxner; Branka Bedenić; Magda Diab-Elschahawi; Michael Berktold; Agnes Wechsler-Fördös; Gernot E Zarfel Journal: Int J Environ Res Public Health Date: 2021-02-23 Impact factor: 3.390