Susceptibility of catheter-related Klebsiella pneumoniae strains to quaternary ammonium compounds under biofilm and planktonic conditions

Canadian Journal Infection Control 33 (4):215-219 (2018)
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Background: The aim of this study was to evaluate the susceptibility of catheter-related Klebsiella pneumoniae isolates to two biocides (benzalkonium chloride and Deconex) under biofilm and planktonic conditions. Methods: A total of 85 strains of K. pneumoniae were isolated from catheters of inpatients hospitalized in four hospitals in Kerman, Iran. Susceptibility to antibiotics and biocides under biofilm and planktonic growths was performed using the microdilution method. Antibiofilm activity of the biocides was determined by microtiter assay. Biofilm eradication was carried out at different periods of time. The presence of cepA and qacEΔ1 genes were detected by polymerase chain reaction (PCR). Results: We found that 15% (n = 12) of the isolates showed strong biofilm activity, 40% (n = 35) displayed moderate activity, 30% (n = 26) demonstrated weak activity, and 15% (n = 12) showed no attachment to microtiter wells. Both the biocides had profound inhibitory activities on planktonic cells (average minimum inhibitory concentration [MIC] 0.06 ± 0.2 mg/ml for Deconex and 0.03 ± 0.1 mg/ml for benzalkonium chloride). They exerted the least antibiofilm activity at a sub-MIC concentration of 0.015 mg/ml. The isolates that formed high biofilm also harboured the cepA gene. Furthermore, a considerable increase in MIC to piperacillin/tazobactam, tetracycline, and cefotaxime was observed for cells grown in biofilm conditions for 24 hours, but all the isolates were sensitive to colistin and tigecycline. These differences were statistically significant, with a p-value of < 0.05. Most of the biofilms were eradicated from the microtiter plate within 30 minutes’ exposure to these biocides. Conclusions: As the data indicates, benzalkonium chloride and Deconex have good potential as hospital disinfectants for catheter-related infections caused by K. pneumoniae in planktonic conditions. Antimicrobial stewardship programs must be performed weekly in our hospitals to improve the quality of antimicrobial use, reduce the use of antibiotics, and shorten the length of hospital stay without increasing mortality rates.
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First archival date: 2019-02-27
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