High rate of MRSA isolates from chlorhexidine-impregnated catheter-related bloodstream infections


Intravenous literature: Ho, C.M., Li, C.Y., Ho, M.W., Lin, C.Y. and Lu J.J. (2012) High rate of qacA/B-positive methicillin-resistant Staphylococcus aureus isolates from chlorhexidine-impregnated catheter-related bloodstream infections. Antimicrobial Agents and Chemotherapy. Aug 20. .


Chlorhexidine has been widely used for infection controls. Although the use of chlorhexidine-impregnated catheters has reduced catheter-related infections, chlorhexidine-resistant Staphylococcus aureus has emerged. The correlation between the existence of the chlorhexidine-resistant genes qacA/B in methicillin-resistant Staphylococcus aureus (MRSA) isolates and the effectiveness of chlorhexidine-impregnated catheters in the prevention of MRSA infections are unknown. Sixty methicillin-sensitive Staphylococcus aureus (MSSA) and 96 MRSA isolates from the blood cultures of different patients were collected, and a case control study was conducted to determine whether more clinical S. aureus isolates from chlorhexidine-impregnated catheter-related bloodstream infections (CRBSI) have the biocide-resistant genes (qacA/B or smr) than those from other infections. The chlorhexidine MIC(50) of MSSA and MRSA isolates were 1 μg/ml and 2 μg/ml, respectively. Results of PCR analyses showed that 3.3% (n=2) of MSSA and 43.8% (n=42) of MRSA isolates harbored qacA/B, and 5% (n=3) of MSSA and 25% (n=24) of MRSA isolates contained smr. With multivariate logistic regression analyses, the significant risk factors for definite CRBSI with chlorhexidine-impregnated catheters were determined to be S. aureus isolates with qacA/B and a chlorhexidine MIC ≥ 2 ug/ml (OR = 9.264 and 8.137, respectively in all 156 S. aureus isolates; OR = 6.097 and 4.373, respectively in the 96 MRSA isolates). Further prospective studies are needed to investigate the transmission of these biocide resistant genes.

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