Effect of N-acetylcystein on Antibiofilm Efficiency of Antibiotics in Staphylococci Isolates

Abstract

Biofilms are often responsible for the difficulties in the treatment of infectious diseases due to their properties that facilitate escape from antibiotic effect and their antiphagocytic effects. At least 65% of all infectious diseases are associated with biofilm-forming bacteria. As Staphylococcus aureus and Staphylococcus epidermidis are among the most common agents of hospital infections and the infections are mostly biofilm-related, they pose an important problem. In infectious isolates, the minimum biofilm eradication concentration (MBEK) values of biofilm forms are much higher than the minimum inhibition concentration (MIC) values of planktonic forms. This situation requires the use of much higher doses of antibiotics in the treatment of infections and causes an increase in antibiotic resistance. The N-acetylcysteine (NAC) molecule is known to be effective against biofilm by disrupting mature biofilms and reducing the adhesion of bacteria to surfaces. In this study, it was aimed to demonstrate i) the biofilm-forming abilities ii) the change in ampicillin and vancomycin MIC values in the presence of NAC molecules, iii) the change in the MBEK values of these antibiotics in the presence of NAC molecule and iv) the change in the expression levels of genes thought to be related to biofilm formation in the presence of the NAC molecule among S.aureus (n= 38) and S.epidermidis (n= 12) isolates isolated from various clinical specimens in Trakya University Health Research and Application Center. In this study, microplate crystal violet method was used to demonstrate the biofilm formation in staphylococci. Broth microdilution and checkerboard method were used to demonstrate the change in the presence of NAC molecule of the MIC and MBEC values of ampicillin and vancomycin. The effect of NAC on the expression of intercellular binding proteins A and D (icaA, icaD) and Staphylococcus regulatory protein A (sarA) genes, which are the genes involved in biofilm formation in staphylococci, was determined by quantitative real-time Polymerase Chain Reaction (qRt-PCR) method. The Student-t test was used to compare the control and experimental groups (concentrations detected with synergy and additive effect); p˂ 0.05 was accepted as the limit value of significance. In this study, when the NAC molecule was used together with ampicillin and vancomycin, it was determined that this combination lowers the MIC values of staphylococcus isolates and staphylococcal biofilm MBEK values; and also the expression levels of icaA, icaD and sarA which were effective in biofilm formation in staphylococci have not changed and decreased. As a result, in this study, it has been determined that the NAC molecule can be a new alternative for combined drug therapy and is promising in terms of bringing a new approach to treatment. In addition, it is thought that it is possible to use the NAC molecule together with different microorganisms and antimicrobial agents, and the results obtained in this study are considered to be guiding for further studies on this subject.