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

Biocides are extensively used in pharmaceutical facilities to control the bioburden level in different areas. An example of active efflux mechanisms are qac A / B proteins and nor A gene which mediate resistance to quaternary ammonium compounds (QACs) in staphylococci. The aim of the present work is to investigate resistance to QACs in staphylococcus isolates recovered from a pharmaceutical facility and to test for the possible interconnection between antibiotic and biocide resistance. A total of 144 isolates identified as Staphylococcus spp were collected from different sterile and non-sterile (non-antibiotic) areas in a pharmaceutical facility in Egypt over a period of 10 months. Screening for biocide resistance was carried out by determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for cetrimide and chlorhexidine by broth microdilution according to CLSI (2009) guidelines. PCR detection of the efflux genes qac A / B and nor A genes was done and showed that 11 isolates were positive for qacAB gene, 2 isolates were positive for norA gene. Inhibition of the efflux pump activity using chlorpromazine was evaluated in qacAB positive isolates where at least 2 fold decrease in their MIC values for both cetrimide and chlorhexidine was observed. The antibiotic susceptibility profile of the biocide resistant isolates was carried out by antibiotic disc diffusion susceptibility testing

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