Molecular detection of antiseptic resistance genes among clinical staphylococcus aureus isolates / Noha Yousry Elsaid ; Supervised Abdelfattah Mohamed Hassan Attia , Hala Elsayed Badawi , Alaa Mohamed Reda

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

Disinfectants and antiseptics are biocides widely used in hospitals and community to prevent spread of pathogens. It has been reported that antiseptic resistance genes, qac{u2019}s, caused tolerance to a variety of biocidal agents, such chlorhexidine digluconate in Staphylococcus spp. isolates. The aim of this study was to detect presence of antiseptic resistance genes (qac A/B and qac C) among MSSA and MRSA clinical isolates. As well as Studying the association between the presence of mecA gene and different antiseptic resistance genes (qac A/B and qac C) in MRSA isolates and determination of the correlation between presence of qac A/B and qac C genes and susceptibility to chlorhexidine. One hundred S. aureus clinical isolates from inpatients and outpatients admitted to Theodor Bilharz Research were defined to the genus and species level and AST was done by Vitek2 system and MRSA was determined.The (MICs) of chlorhexidine were determined. PCR was done to detect presence of mecA gene as well as quaternary ammonium resistance genes qacA/B and qacC among all isolated S. aureus. Out of 100 S. aureus 84/100 (84%) isolates were MRSA from which 52 (61.9%) isolates were considered susceptible to chlorhexidine (MIC < 4 mg/L) while 32 (38.1%) had reduced susceptibility (MIC {u2265}4 mg/L). On the other hand, 11(68.8%) MSSA isolates were considered susceptible to chlorhexidine while 5 (31.2%) had reduced susceptibility. QacA/B gene was more dominant being detected 34/100 (34%) of S. aureus isolates [MRSA = 29 (34.5%), MSSA = 5(31.2%)], while qacC was less common, only detected in 5/100(5%) of S. aureus isolates [MRSA = 5(5.95%), MSSA = 0(0%)]. We anticipate that clinical use of chlorhexidine will continue to increase and it will be important to be alert to the possibility that this may lead to the emergence of new clones with reduced susceptibility. The overuse of antiseptics in the absence of efficacy data should be discouraged

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