Thesis (Ph.D.) - Cairo University - Faculty of Pharmacy - Department of Microbiology and Immunology

The present study was performed on 150 non-duplicate A. baumannii clinical isolates collected from July 2012 to September 2013. Biochemical identification was done and identification to species level was performed by Vitek-2c automatic system and confirmed by MALDI-TOF MS then molecular confirmation was done via PCR amplification and sequencing of the intrinsic blaOXA51-like gene. Antimicrobial susceptibility testing was performed and MIC was determined by VITEK-2 and confirmed for imipenem, amikacin and tigecycline by Etest strips. Real time PCR was done to screen for the presence of blaNDM-1, blaOXA23-like, blaOXA24-like, blaOXA58-like, blaIMP, blaVIM and blaKPC genes expression. Carbapenems and aminoglycosides-resistance encoding genes were detected by Multiplex PCR amplification and sequencing. ISAba1 was detected in all our isolates. Genes encoding resistance to aminoglycosides detected were as follows: armA, aac6, aac3, aac8, aph, aad, and ant-2. Other genes of resistance were detected by standard PCR and sequencing as ESBLs. The sequencing results for the QRDRs of gyrA revealed the presence of single mutation Gly145Asp in the gyrA subunits and double mutations Ser81Leu and Gly145Asp in the gyrA subunits. Genetic mapping of carbapenemases, AME, and armA was performed. MLST allowed us to identify 27 different sequence types (STs), 11 of which were novel. It was found that the ST2 clonal group predominated. Our results revealed that different clonal lineages are circulating among Egyptian hospitals. Additionally four clonal complexes (CCs) were identified. The main CC was CC2

Issued also as CD