Investigation of pathotype, resistotype and genotype clustering in acinetobacter baumannii isolates of clinical origin

ABSTRACT Deniz, İ. (2018). Investigation of Pathotype, Resistotype and Genotype Clustering in Acinetobacter baumannii Isolates of Clinical Origin. Yeditepe University, Institute of Health Sciences, Department of Molecular Medicine, M.Sc. Thesis, İstanbul. Acinetobacter baumannii is a nonfermentative, Gram-negative bacterium that has been shown to be a multidrug resistant pathogen responsible for severe infectious diseases such as pneumonia, urinary tract infections, septicemia and meningitis. The aim of this study was to investigate the aggregation properties of A. baumannii in terms of infectious (pathotype), antimicrobial resistance phenotype (resistotype) and genotype. A total of 36 A. baumannii bacterial isolates collected between July to November 2015 from the patients who were hospitalized in eight hospitals representing the biogeography of Istanbul.Specimen-level bacterial identification and antibiotic susceptibility tests were performed respectively in MALDI-TOF-MS and VITEK2 automated systems and molecular epidemiological typing tests were performed in automated DiversiLab rep-PCR system. The single sample chi-square test and Fisher's exact test were used in statistical analysis. In pathotype analysis, 10 (10/36, 27.7%) were identified as infectious agents and 26 (26/36, 72.2%) were colonization. A total of 25 resistotypes were detected. Resistance to carbapenem antibiotics was 88.8% (32/36). A total of eight genotypes (GC01-GC08) were identified. GC01 contained 30 isolates (83.3%, 30/36). In GC01, four genotypes (G01-G04) were detected. All of the infection isolates (10/10, 100%) were in GC01. A total of 11 genotypes (G01-G11) were detected. Among the genotypes, G01 (14/36, 38.8%) was found to be dominant. In conclusion, the prevalent GC01 genotype cluster of A. baumannii isolates collected from eight major hospitals in İstanbul were significantly associated with infection pathotype (p=0.021). In the study isolates, pathotype-genotype clustering (i.e. infectivity and GC01) was detected, however, resistotype diversity was found to be high and did not show any clustering. "Pathotype-Resistotype-Genotype" data indicated that GZT hospital might be a "source" for spread, whereas FSM and HNH might be of "sink-reciprocal type", and other hospitals of "sink-black hole type". Key Words: Acinetobacter baumannii, repetitive-PCR typing, molecular epidemiological typing, source-sink dynamic