Evaluation of antibacterial activity of five biocides and the synergistic effect of biocide/EDTA combinations on biofilm-producing and non-producing Stenotrophomonas maltophilia strains isolated from clinical specimens in Iran

Abstract

Background The overuse of biocides in healthcare-facilities poses risk for emergence and spread of antibiotic resistance among nosocomial pathogens. Hospital-acquired infections due to S. maltophilia have been increased in the recent years and with its various resistance mechanisms contribute to patient morbidity and mortality in hospitals. The current study aimed to evaluate the susceptibility of biofilm-producing and non-producing S. maltophilia clinical isolates to five commonly used hospital biocides, alone and in combination with EDTA to examine the synergistic effect of combining EDTA on the bactericidal activity of them by microbroth dilution method. As well as the frequency of efflux genes encoding resistance to biocides among isolates. This study also intended to assess the effect of exposure of S. maltophilia isolates to sub-inhibitory concentrations of sodium hypochlorite upon the antimicrobial susceptibility patterns. Results Based on minimum inhibitory and bactericidal concentrations of biocides sodium hypochlorite 5% (w/v) and ethyl alcohol 70% (v/v) were the strongest and weakest biocides against S. maltophilia isolates, respectively. The combination of EDTA with biocides significantly increased the effectiveness of the studied biocides. Exposure to sub-inhibitory concentration of sodium hypochlorite showed a significant change in the susceptibility of isolates towards ceftazidime (p = 0.019), ticarcillin/clavulanate (p = 0.009), and chloramphenicol (p = 0.028). As well as among the isolates examined, 94 (95%) were able to produce biofilm. The frequency of sugE1 resistance genes was found in 90.7% of our clinical S. maltophilia isolates. None of the isolates carried qacE and qacEΔ1 gene. Conclusions The current study recommended that using the mixture of biocides with EDTA can be effective in reducing nosocomial infections. Also, this study demonstrated that exposure to sub-inhibitory concentrations of sodium hypochlorite leads to reduced antibiotic susceptibility and development of multidrug-resistant S. maltophilia strains.

The Mla system and its role in maintaining outer membrane barrier function in Stenotrophomonas maltophilia

“…For example, a drug aimed at inhibiting this system could mimic the known synergistic effects of EDTA with antibiotics. EDTA in combination with antibiotics of various classes or disinfectants has been shown to be effective against clinical strains of S. maltophilia or for the decontamination of medical devices ( Passerini de Rossi et al., 2012 ; Anari et al., 2022 ). An antimicrobial therapy based on the MlaC transporter is also very attractive to eradicate polymicrobial biofilms formed by Gram-negative pathogens.…”

Optimisation and identification of anchovy antimicrobial peptides by enzymolysis and untargeted proteomic profiling

“…The 96‐well plate was incubated at 37 °C for 24 h. The absorbance was measured at wavelength of 600 nm. The lowest concentration that showed no increase in the optical density read on microplate reader was considered as MIC and the lowest concentration at which the bacteria did not grow obviously was considered as MBC (Anari et al ., 2022; Jam et al ., 2022). Each test was performed three times.…”

Metabolic Changes in Pseudomonas oleovorans Isolated from Contaminated Construction Material Exposed to Varied Biocide Treatments

“…The type of mutation that can render microorganisms less susceptible to biocides over time is often referred to as antimicrobial resistance (AMR) [ 19 ]. Antimicrobial resistance occurs when microorganisms, such as bacteria, undergo genetic changes that enable them to survive exposure to the biocidal agents that were once effective against them [ 20 , 21 ]. Pseudomonas species are notorious for their ability to form biofilms, which provide a protective matrix and resist the effects of biocides [ 22 , 23 ].…”