Thesis (M.Sc.) - Cairo University - Faculty of Pharmacy - Department of Microbiology and Immunology

Acinetobacter baumannii is a remarkable hospital pathogen, notably due to the dissemination of highly multidrug resistant isolates and the treatment options for infections caused by multi-drug resistant (MDR) A. baumannii strains constitute a strong challenge. The virulence factors of this organism such as biofilm formation, bacterial adherence, and bacterial invasion and efflux pumps help the bacterium to survive in diverse environmental conditions and facilitate the development of an infection. Antiseptics are frequently used for the management of MDR pathogens in hospitals and their consistent use in hospitals has elevated concerns about its resistance. The aim of this study was to determine the effect of subminimum inhibitory concentrations (sub-MICs) of selected antimicrobial agents (amikacin, imipenem, benzalkonium chloride (BZC), and chlorhexidine) and natural product (garlic) on biofilm formation, bacterial adherence and invasion and the emergence of resistance among A. baumannii clinical isolates. Susceptibility profiles of 50 non-repetitive A. baumannii isolated from admitted patients in two tertiary care hospitals in Cairo, Egypt to eight different antibiotics were investigated. MIC of various antibiotics, antiseptics and garlic were determined by the broth microdilution method. Quantification of biofilm formation was carried out using a microtiter plate assay. The ability of test compounds to affect the bacterial adherence and invasion was investigated using Type II pneumocyte cell line A549 derived from a human lung carcinoma and the bacterial cells count was determined in each well using flow cytometer. Screening for the presence of antiseptic resistance gene qacA/B was done using PCR

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