Abstract
Biocides are frequently used as preservative, disinfectant and sterilizer against many microorganisms in hospitals, industry and home. However, the reduced susceptibility rate of Pseudomonas aeruginosa (P. aeruginosa) strains to biocides is increasing. The aim of this study was to evaluate the antimicrobial activity of four frequently used biocides against P. aeruginosa and to determine the prevalence of genes involved in biocide resistance. A total of 76 clinical isolates of P. aeruginosa strains were used in the present study. The minimum inhibitory concentrations (MICs) of four biocides, i.e. chlorhexidine digluconate, benzalkonium chloride, triclosan and formaldehyde, against P. aeruginosa strains were determined using agar dilution method. In addition, the prevalence of biocide resistance genes was determined using the polymerase chain reaction (PCR) method. In the present study, the highest MIC90 and MIC95 (epidemiological cut-off) values were observed for benzalkonium chloride (1024μg/mL), followed by formaldehyde (512μg/mL), triclosan (512μg/mL) and chlorhexidine digluconate (64μg/mL). Furthermore, the prevalence of qacEΔ1, qacE, qacG, fabV, cepA and fabI genes were 73.7% (n = 56), 26.3% (n = 20), 11.8% (n = 9), 84.2% (n = 64), 81.5% (n = 62) and 0% (n = 0), respectively. A significant association was observed between the presence of biocide resistance genes and MICs (p < 0.05). Furthermore, there was no significant association between the presence of biocide resistance genes and antibiotic resistance (p > 0.05), except for levofloxacin and norfloxacin antibiotics and qacE and qacG genes (p < 0.05). Our results revealed that chlorhexidine digluconate is the most effective biocide against P. aeruginosa isolates in Ardabil hospitals. However, we recommend continuous monitoring of the antimicrobial activity of biocides and the prevalence of biocide-associated resistance genes for a better prevention of microorganism dissemination and infection control in hospitals.
Highlights
Pseudomonas aeruginosa (P. aeruginosa) is a Gram-negative bacillus, which is frequently isolated from hospital environments, especially from medical equipments used in intensive care units (ICUs) [1,2,3]
Our results revealed that chlorhexidine digluconate is the most effective biocide against P. aeruginosa isolates in Ardabil hospitals
The highest MIC90 was observed for benzalkonium chloride (MIC90=1024 μg/mL), followed by formaldehyde (MIC90=512 μg/mL), triclosan (MIC90=512 μg/mL) and chlorhexidine digluconate (MIC90=64 μg/mL), it seems that chlorhexidine digluconate and benzalkonium chloride had the highest and the lowest effects, respectively, in terms of growth inhibition of P. aeruginosa isolates in this study
Summary
Pseudomonas aeruginosa (P. aeruginosa) is a Gram-negative bacillus, which is frequently isolated from hospital environments, especially from medical equipments used in intensive care units (ICUs) [1,2,3]. The risk of P. aeruginosa infections in ICU-hospitalized patients is high (up to 30%) despite applying hygiene programs [5] Such a high prevalence can be attributed to the resistance of P. aeruginosa strains against a variety of antiseptics and disinfectants over time [6]. Several mechanisms of resistance to antibiotics and tolerance to biocides have been identified in P. aeruginosa strains including: 1) simple growth requirements and ability of biofilm formation, 2) enzymatic degradation, 3) target site modification, 4) outer membrane impermeability, and 5) presence of efflux pumps These properties are involved in bacterial persistence in medical environments and development of nosocomial infections [2, 8,9,10,11,12,13]. The aim of this study was to evaluate the antimicrobial activity of four frequently used biocides against P. aeruginosa and to determine the prevalence of genes involved in biocide resistance
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