Biocide’s susceptibility and frequency of biocide resistance genes and the effect of exposure to sub-inhibitory concentrations of sodium hypochlorite on antibiotic susceptibility of Stenotrophomonas maltophilia

Abstract

Background: The overused of biocides in healthcare-facilities poses risk for emergence and spread of antibiotic resistance among nosocomial pathogens. Hospital-acquired infections due to S. maltophilia particularly in the immunocompromised patients have been increased. The objective of this study was to evaluate the susceptibility of S. maltophilia clinical isolates to commonly used biocides in hospitals, as well the frequency of biocides resistance gene among them. 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. Methods: This study included 97 S. maltophilia isolates. Biofilm formation was determined by microtiter plate assay. The susceptibility tests of five biocides were studied against all S. maltophilia isolates by microbroth dilution method. Susceptibility of isolates to antibiotics by disk diffusion method were compared before and after exposure to sub-inhibitory concentrations of sodium hypochlorite. Presence of qacE, qacEΔ1, SugE genes was screened by PCR. Results: Based on minimum inhibitory and bactericidal concentrations of biocides sodium hypochlorite 5% and ethyl alcohol 70% were the strongest and weakest against S. maltophilia isolates, respectively. The frequency of sugE gene resistance genes was found to be high (90.7%) in our clinical S. maltophilia isolates. None of the isolates carried qacE and qacEΔ1 gene. Exposure to sub-inhibitory concentration of sodium hypochlorite showed significantly change the susceptibility of isolates towards ceftazidime (P = .019), ticarcillin/clavulanate (P = .009). and chloramphenicol (P = .028). Conclusions: This study demonstrated that exposure to sub-inhibitory concentration of sodium hypochlorite leads to reduced antibiotic susceptibility and development of multidrug-resistant S. maltophilia strains.

Evaluating the effectiveness of Chlorhexidine on Gram-positive and Gram-negative bacteria in Iran: a systematic review

“…One of the 15 full-text examined papers had a sample size of fewer than 10 isolates and also, two studies were performed just on non-clinical isolates so, did not meet our inclusion criterion. Finally, 12 papers met the inclusion criteria and were submitted to our evaluation (1,(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18). A owchart of the literature search, the selection procedures and reasons for exclusion are presented in Figure 1.…”