Enhanced textile dye removal from wastewater using natural biosorbent and Shewanella algae B29: Application of Box Behnken design and genomic approach.

In this study, Box-Behnken design combining seven factors at three levels were used to optimize the elimination of CI Reactive Red 66 in artificial seawater, by the combination of eco-friendly bio-sorbents and acclimated halotolerant microbial strain. Results showed that macro-algae and cuttlebone (2 %) were the best natural bio-sorbent. Additionally, the selected halotolerant strain able to rapidly remove dye was identified as Shewanella algae B29. The optimization process revealed that decolourization of CI Reactive Red 66 yields reached 91.04 % under the following variable values: dyes concentration (100 mg/l), salinity (30 g/l), peptone (2 %), pH (5), algae C (3 %), cuttlebone (1.5 %) and agitation (150 rpm). The whole genome analysis of S. algae B29 demonstrated the presence of several genes coding for valuable enzymes involved in textile dyes biotransformation, adaptation to stress as well as biofilm formation implying its potential use in biological textile wastewater treatment.

Computational screening of natural compounds as putative quorum sensing inhibitors targeting drug resistance bacteria: Molecular docking and molecular dynamics simulations.

Quorum sensing (QS) is a bacterial communication strategy controlling cells density, biofilm formation, virulence, sporulation, and survival. Since QS is considered a virulence factor in drug-resistant pathogenic bacteria, inhibition of QS can contribute to control the spread of these bacteria. We propose in this study to test in silico, 19 natural compounds for their potential to inhibit QS transcriptional regulators of Pseudomonas aeruginosa (LasR and PqsE) and Chromobacterium violaceum (CviR and CviR'). Molecular docking was performed to explore the binding energies between selected compounds, and QS signaling proteins. Additionally, molecular dynamics (MD) simulations of the complexes protein-ligand were tested to evaluate the stability of the complexs throughout the simulation process. The simulation interaction diagram (SID) was achieved to compute the radius of gyration (rGyr), solvent accessible surface area (SASA), intramolecular HBs, molecular surface area (MolSA), and polar surface area (PSA). Additionally, the physicochemical properties, pharmacokinetics, drug-likeness, and toxicity analysis of the best-selected compounds were determined. Among these compounds, catechin and nakinadine B were identified as potent QS antagonists that showed the best XP GScore and stable interaction during molecular dynamic simulation. Catechin interacts with LasR and CviR' displaying XP GScore -10.969 kcal/mol and -9.936 kcal/mol respectively. Additionally, nakinadine B interacts with PqsE and CviR giving XP GScore -7.442 kcal/mol and -10.34 kcal/mol respectively. RMSD plot analysis showed that both catechin and nakinadine B were stable during 50 ns simulation time with the tested target proteins. The predictive result of toxicity demonstrated that catechin and nakinadine B doesn't induce cytotoxicity, immunotoxicity, carcinogenicity, mutagenicity, hepatotoxicity and were at medium risk for hERG inhibition. Also they were found to be inactive for androgen receptor and aromatase. These results imply that catechin and nakinadine B may be suggested as QS modulators, which may reduce the virulence factors of drug-resistant bacteria.

Aflatoxin B1 degradation by microorganisms isolated from Kombucha culture.

Aflatoxin B1 (AFB1) is the most harmful mycotoxin. Aflatoxin occurrence in tea makes this beverage unsuitable for consumption and presented risks to human health. Therefore, researches in aflatoxin microbial degradation are necessary to overcome this problem. Kombucha beverage is associated with health promoting effects. Thus, novel strains (Lactic acid bacteria and yeasts) were isolated from a Kombucha culture and assessed for AFB1 degradation in the liquid medium (Man Rogosa and Sharpe broth, yeast extract peptone dextrose broth and black tea). The main strains involved in AFB1 decontamination were identified based on DNA sequencing and the toxicity of the new products was evaluated on Hep2 cells and on Brine shrimp (Artemia salina). Our results showed that after 7 days of fermentation, kombucha was able to degrade 97% of AFB1 in black tea. Moreover, the effective yeasts present in Kombucha were identified as Pichia occidentalis, Candida sorboxylosa and Hanseniaspora opuntiae and the highest AFB1 degradation capacity was accorded to P. occidentalis (59%) when cultivated in black tea. Data on cytotoxicity tests on Hep2 cells and Brine shrimp (Artemia salina) showed that the biodegraded products were less toxic than pure AFB1. These findings suggest that, kombucha isolated strains could be potential candidates for application in the food and feed industry with a potential aflatoxin B1 detoxification properties.

Virucidal Effect of Guggulsterone Isolated from Commiphora gileadensis.

Commiphora gileadensis, locally known as becham, is a plant used in traditional Arabian medicine for treating headache, constipation, stomach, joint pain, and inflammatory disorders. Several studies have reported its antibacterial properties; however, no study has demonstrated its antiviral activity. This study aimed to evaluate the antiviral activity of C. gileadensis as well as to isolate its active compound and investigate its mode of action. This activity was evaluated using 4 viruses, herpes simplex virus type 2 (HSV-2), respiratory syncytial virus type B (RSV-B), coxsackie virus B type 3, and adenovirus type 5 by performing the plaque reduction assay and the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays for enveloped and nonenveloped viruses, respectively. The methanol extract of C. gileadensis leaves only showed antiviral activity against enveloped viruses with a selectivity index of 11.19 and 10.25 for HSV-2 and RSV-B, respectively. The study of the mechanism underlying antiviral activity demonstrated a virucidal effect by direct contact with these target viruses. The active compound, isolated using bio-guided assays involving TLC, was identified as guggulsterone by HPLC-diode array detection coupled with electrospray ionization mass spectrometry. Guggulsterone is an antagonist of the bile acid receptor and a modulator of cholesterol metabolism; however, its antimicrobial properties have been reported for the first time in this study.

Analysis of a long term starved Pseudomonas aeruginosa ATCC27853 in seawater microcosms.

The persistence of pathogenic bacteria in the marine environment has been thoroughly investigated. The potential threat that these microorganisms pose to public health in recreational waters has always been a concern. In this study, the persistence and the response of Pseudomonas aeruginosa ATCC27853 to starvation and osmotic stress were studied after its incubation in sterilized seawater during 12 months. Three different colonial variants were isolated: A7 after one month, and A81 and A82 after 8 months of incubation period. The incubation effect on the bacterial phenotype and genotype were studied by analyzing modifications in morphology, antibiotic and metal resistance, molecular typing (PFGE and MLST), pigment production and virulence factors. The starved variants showed three different colony forms, but an indistinguishable PFGE pattern and belonged to ST155, as P. aeruginosa ATCC27853. The starved variants maintained the susceptibility to the 13 tested antibiotics, with the exception of the imipenem-resistant A82 strain, which also showed a small colony variant phenotype and the highest values of tolerance to the CuSO4 + NaCl combination. Significant differences were detected in the pigment production, the elastase activity and cytotoxic potential of the starved isolates in comparison to P. aeruginosa ATCC27853. Long-term exposure to stress, such as the incubation in seawater, was shown to induce different responses in P. aeruginosa, including virulent and resistant phenotypes.

Use of lactic acid bacteria for the inhibition of Aspergillus flavus and Aspergillus carbonarius growth and mycotoxin production.

Almonds and peanuts are a rich source of proteins, vitamins and unsaturated fatty acids. However, they can be also contaminated by mycotoxigenic fungi; a reason that has enhanced to investigate efficient strategies of management of these fungal contaminations. Some Lactic acid bacteria have been proven capable of inhibiting growth and mycotoxin production in livestock and transform it into nontoxic derivatives. In this work, four lactic acid bacteria (LAB) were tested for their abilities to inhibit the growth and mycotoxin production of Aspergillus flavus and Aspergillus carbonarius. Antifungal activity was evaluated in agar medium as well as in almonds and peanuts. Results showed that LAB significantly inhibited Aspergillus flavus and Aspergillus carbonarius in agar medium but none of the strains were able to completely inhibit fungal growth. The highest fungal growth inhibition was obtained using L. kefiri FR7 (51.67% and 45.56% growth inhibition of A. flavus and A. carbonarius, respectively). The cell-free supernatants (CFS) from LAB reduced fungal growth with average growth inhibitions ranging from 13.33% to 40.56% and 12.78% to 37.78% for A. flavus and A. carbonarius, respectively. We noted also that cell-free supernatants at pH7 (CFS-pH7) from the entire tested LAB did not inhibit fungal growth. L. kefiri FR7 was the most effective strain in mycotoxin suppression with a reduction percentage reaching 97.22%, 95.27% and 75.26% for AFB1, AFB2 and OTA respectively. Moreover, the inoculation of L. kefiri FR7 in almonds artificially contaminated with A. flavus decrease 85.27% of AFB1 and 83.94% of AFB2 content after 7 days of incubation. On the other hand, application of L. kefiri FR7 in peanuts artificially contaminated with A. carbonarius reduced OTA content to 25%. Our study revealed the potential use and application of L. kefiri FR7 in the control of fungi growth and mycotoxins production in almonds and peanuts.

Review: Biotechnology of mycotoxins detoxification using microorganisms and enzymes.

Mycotoxins are secondary metabolites produced by various toxigenic fungi belonging to the genera Aspergillus, Fusarium and Penicillium. They have mutagenic, teratogenic, carcinogenic, immunosuppressive and endocrine disrupting effects on both humans and animals. The ubiquitous occurrence and heat stability of these mycotoxins during food and feed processing pose serious health problems in human and animals. Therefore successful biotechnological detoxification tools are in great demand. Recently, the use of bacteria, yeast, moulds and enzymes to mitigate/bind or biodegrade various mycotoxins is a novel strategy used for mycotoxins removal. In this review, recent development in biological control of mycotoxins removal and detoxification will be discussed.

Use of extracellular polysaccharides, secreted by Lactobacillus plantarum and Bacillus spp., as reducing indole production agents to control biofilm formation and efflux pumps inhibitor in Escherichia coli.

The overuse of antibiotics and biofilm formation ability has led to the emergence of bacterial resistant strains. The combined use of several antibiotics has been found as an efficient strategy to overcome this resistance. In this study, two exopolysaccharides (EPS) obtained from Lactobacillus plantarum (EPS-Lp) and Bacillus spp. (EPS-B), isolated from a traditional Tunisian food "ricotta cheese" and hypersaline environment respectively, were used to counteract the biofilm formation and efflux pumps activities in Escherichia coli ATCC35218. The obtained results revealed that the tested EPSs can be effective against E. coli at a concentration > 1 mg/ml and were able to modulate biofilm formation by 50%. Moreover, at a concentration of 512 µg/ml, the tested EPSs inhibit the EtBr efflux in the tested bacteria and no significant difference was shown compared to cells treated with reserpine (P > 0.05). The positive effect of the tested EPSs may be due to the decrease of Indole production level proposed as a signal involved in quorum sensing and through the significant reduction of the hydrophobicity percentage between the treated and untreated cells. Overall, EPS-Lp and EPS-B, when used at appropriate concentration, may inhibit biofilm formation and reduce efflux pumps implicated in bacterial adhesion and antimicrobial resistance. These results make them an interesting candidate in the design of a new strategies to control bacterial biofilm-associated infections.

Synthesis and evaluation of antibacterial and antibiofilm activities of pyridin-2-yl hexanoate.

Synthesized Pyridin-2-yl hexanoate was screened for its antibacterial and antibiofilm activities using the broth microdilution method and XTT assay respectively. The obtained results revealed that synthesized molecule inhibited the growth of pathogenic bacteria (MICs value ranged from 80 to 640 µg ml-1). Moreover, it induced a strong antibiofilm effect against Gram positive cocci (BIC50 was 366, 378 and 412 µg ml-1 for Streptococcus mutans ATCC 25175, Streptococcus salivarius ATCC 13419 and Streptococcus oralis ATCC 6249 respectively). Basis on these results, pyridin-2-yl hexanoate may be considered as effective compound with antibacterial and antibiofilm activities.

Synergistic effect of eugenol, carvacrol, thymol, p-cymene and γ-terpinene on inhibition of drug resistance and biofilm formation of oral bacteria.

Dental caries remains the most prevalent oral infectious disease worldwide. In this study, the antibacterial and the antibiofilm activities of five essential oils (EO's): eugenol (EUG), carvacrol (CAR), thymol (TYH), p-cymene (CYM) and γ-terpinene (TER) were tested (alone or in combinaison with tetracycline) against oral bacteria. In addition, their potential roles to enhance the accumulation of ethidium bromide (EtBr) in bacterial cells were tested. Our results indicated that EO's induced a selective antimicrobial activity. A synergistic effect of EO's and tetracycline (TET) was noticed with a reduction rate ranged from 2 to 8-fold. In addition, the efflux of EtBr was inhibited with a decrease in loss of EtBr from the bacteria. On the other hand a significant anti-biofilm activities of EO's (alone or combined with antibiotics) was noticed. In conclusion the tested EO's may be considered as a potential natural source with a resistance-modifying activity and may be applied to eradicate bacterial biofilm.

Adsorption of aflatoxin B1, zearalenone and ochratoxin A by microorganisms isolated from Kefir grains.

A strategy to reduce the deleterious effects of mycotoxins is to use dietary supplements that contain microorganisms that bind mycotoxins and decrease their gastrointestinal absorption. Novel strains were isolated from a Kefir culture and assessed for their mycotoxin adsorption and biotransformation ability. The most active strains were identified using DNA sequencing, and the stability of microorganism/mycotoxin complexes was evaluated using buffer solutions to simulate the pH conditions in the gastrointestinal tract. Our results showed that the microorganism consortium of Kefir grains adsorbed 82 to 100% of aflatoxin B1 (AFB1), zearalenone (ZEA) and ochratoxin A (OTA) when cultivated in milk. The main strains that were capable of mycotoxin adsorption were identified as Lactobacillus kefiri, Kazachstania servazzii and Acetobacter syzygii. The strain L. kefiri KFLM3 was the most active, adsorbing 80 to 100% of the studied mycotoxins when cultivated in milk. Nonetheless, the strain K. servazzii KFGY7 retained more mycotoxin after the desorption experiments (65, 69 and 67% for AFB1, OTA and ZEA, respectively). These findings suggest that Kefir consumption may help to reduce gastrointestinal absorption of these mycotoxins and consequently reduce their toxic effects. The isolated strains may be of interest for the development of fermented dairy products for human consumption that have a new probiotic characteristic, the adsorption of mycotoxins.

Modulation of drug resistance and biofilm formation of Staphylococcus aureus isolated from the oral cavity of Tunisian children

Abstract Objectives: This study aims to investigate the antimicrobial and the anti-biofilm activities of Lactobacillus plantarum extract (LPE) against a panel of oral Staphylococcus aureus (n = 9) and S. aureus ATCC 25923. The in vitro ability of LPE to modulate bacterial resistance to tetracycline, benzalchonium chloride, and chlorhexidine were tested also. Methods: The minimum inhibitory concentrations (MICs) and the minimal bactericidal concentrations of Lactobacillus plantarum extract, tetracycline, benzalchonium chloride and clohrhexidine were determined in absence and in presence of a sub-MIC doses of LPE (1/2 MIC). In addition, the LPE potential to inhibit biofilm formation was assessed by microtiter plate and atomic force microscopy assays. Statistical analysis was performed on SPSS v. 17.0 software using Friedman test and Wilcoxon signed ranks test. These tests were used to assess inter-group difference (p < 0.05). Results: Our results revealed that LPE exhibited a significant antimicrobial and anti-biofilm activities against the tested strains. A synergistic effect of LPEs and drug susceptibility was observed with a 2–8-fold reduction. Conclusion: LPE may be considered to have resistance-modifying activity. A more detailed investigation is necessary to determine the active compound responsible for therapeutic and disinfectant modulation.

Use of carvacrol, thymol, and eugenol for biofilm eradication and resistance modifying susceptibility of Salmonella enterica serovar Typhimurium strains to nalidixic acid.

The Aims of the study was to evaluate the antibacterial susceptibility and the biofilm eradication of three natural compounds carvacrol (CAR), thymol (TH) and eugenol (EUG), alone or in combination with nalidixic acid (NA) against twelve Salmonella Typhimurium strains. The minimum inhibitory concentration (MIC) and the minimum biofilm eradication concentration (BEC50) of the tested compounds (CAR, TH and EUG) and their combinations with NA were evaluated. In order to assess whether these bacteria had active efflux pumps, ethidium bromide (EtBr) accumulation assays was achieved using spectrophotometric accumulation assays. Moreover, scanning electron microscopy was used to visualize the bacterial biofilm formation on stainless steel surfaces after exposed to NA, CAR, TH and EUG alone and in combination. TH was the most effective essential oil, with the lowest MICs values ranging from 32 to 128 µg/mL followed by EUG and CAR. In addition, the combination of NA with the different compounds enhances antibiotic susceptibility of the tested bacterial strains. These results were confirmed by EtBr accumulation assays. A pronounced effect in decreasing biofilm mass was also noticed. Moreover, SEM revealed that bacterial membrane was disrupted and a complete loss of membrane integrity was also evident. The combination of natural compounds with antibiotic enhances bacterial susceptibility to NA. This combination ameliorates eradication of biofilm formed by S. Typhimurium on polystyrene microtitre plates. Additionally, this synergy induces an alteration of the bacterial cell surface visualized by SEM.

Modulation of drug resistance and biofilm formation of Staphylococcus aureus isolated from the oral cavity of Tunisian children.

OBJECTIVES: This study aims to investigate the antimicrobial and the anti-biofilm activities of Lactobacillus plantarum extract (LPE) against a panel of oral Staphylococcus aureus (n=9) and S. aureus ATCC 25923. The in vitro ability of LPE to modulate bacterial resistance to tetracycline, benzalchonium chloride, and chlorhexidine were tested also. METHODS: The minimum inhibitory concentrations (MICs) and the minimal bactericidal concentrations of Lactobacillus plantarum extract, tetracycline, benzalchonium chloride and clohrhexidine were determined in absence and in presence of a sub-MIC doses of LPE (1/2 MIC). In addition, the LPE potential to inhibit biofilm formation was assessed by microtiter plate and atomic force microscopy assays. Statistical analysis was performed on SPSS v. 17.0 software using Friedman test and Wilcoxon signed ranks test. These tests were used to assess inter-group difference (p<0.05). RESULTS: Our results revealed that LPE exhibited a significant antimicrobial and anti-biofilm activities against the tested strains. A synergistic effect of LPEs and drug susceptibility was observed with a 2-8-fold reduction. CONCLUSION: LPE may be considered to have resistance-modifying activity. A more detailed investigation is necessary to determine the active compound responsible for therapeutic and disinfectant modulation.

Use of juglone as antibacterial and potential efflux pump inhibitors in Staphylococcus aureus isolated from the oral cavity.

In this study the minimal inhibitory concentration (MICs) of tetracycline (Tet), erythromycin (Ery) and benzalkonium chloride (BC) in absence and in presence of a sub-MIC of juglone (Jug) were determined. In addition, the Ethidium bromide (EtBr) efflux assay was performed to assess the effect of Jug on EtBr cells accumulation. Our results showed a selective antimicrobial activity of Jug against the tested strains. A synergistic effect of Jug, drugs (Tet and Ery) and disinfectant (BC) was noticed with a reduction rate varied from 2 to 16-fold. In addition, the efflux of EtBr was inhibited depending on the Jug concentration. In the presence of Jug, a decrease in loss of EtBr from bacteria was observed. The concentration inducing 50 % of EtBr efflux inhibition after 15 min was about 182 µg ml-1 for S. aureus ATCC 25923, 236 µg ml-1 for S. aureus B193 and 195 µg ml-1 for S. aureus B456. It appears from this study that Jug may be used as a natural source for resistance-modifying activity in same bacteria.

Anti-bacterial and anti-biofilm activity of probiotic bacteria against oral pathogens.

In this study, three lactic acid bacteria (LAB), isolated from barley, traditional dried meat and fermented olive were characterized and tested for their anti-bacterial and anti-biofilm activities against oral bacteria. Our results revealed that the tested LAB were γ-hemolytic and were susceptible to four antibiotics. All the strains were resistant to low pH, bile salt, pepsin and pancreatin. Furthermore, FB2 displayed a high aut-oaggregative phenotype (99.54%) while FF2 exhibited the best co-aggregation rate. Concerning the microbial adhesion to solvent, FB2 was the most hydrophobic strain (data obtained with chloroform and n-hexadecane). In addition Pediococcus pentosaceus FB2 and Lactobacillus brevis FF2 displayed a significant inhibitory effect against Streptococcus salivarius B468 (MIC = 10%). Moreover the selected strains were able to inhibit biofilm formation of Bacillus cereus ATCC14579 (MBIC50 = 28.16%) and S. salivarius B468 (MBIC50 = 42.28%). The selected LAB could be considered as candidate probiotics for further application in functional food and mainly in the prevention of oral diseases.

Molecular identification of potential denitrifying bacteria and use of D-optimal mixture experimental design for the optimization of denitrification process.

Three bacterial strains (TE1, TD3 and FB2) were isolated from date palm (degla), pistachio and barley. The presence of nitrate reductase (narG) and nitrite reductase (nirS and nirK) genes in the selected strains was detected by PCR technique. Molecular identification based on 16S rDNA sequencing method was applied to identify positive strains. In addition, the D-optimal mixture experimental design was used to optimize the optimal formulation of probiotic bacteria for denitrification process. Strains harboring denitrification genes were identified as: TE1, Agrococcus sp LN828197; TD3, Cronobacter sakazakii LN828198 and FB2, Pedicoccus pentosaceus LN828199. PCR results revealed that all strains carried the nirS gene. However only C. sakazakii LN828198 and Agrococcus sp LN828197 harbored the nirK and the narG genes respectively. Moreover, the studied bacteria were able to form biofilm on abiotic surfaces with different degree. Process optimization showed that the most significant reduction of nitrate was 100% with 14.98% of COD consumption and 5.57 mg/l nitrite accumulation. Meanwhile, the response values were optimized and showed that the most optimal combination was 78.79% of C. sakazakii LN828198 (curve value), 21.21% of P. pentosaceus LN828199 (curve value) and absence (0%) of Agrococcus sp LN828197 (curve value).

Drug resistance of bacterial dental biofilm and the potential use of natural compounds as alternative for prevention and treatment.

Oral diseases, such as dental caries and periodontal disease are directly linked with the ability of bacteria to form biofilm. The development of dental caries involves acidogenic and aciduric Gram-positive bacteria colonizing the supragingival biofilm (Streptococcus, Lactobacillus and Actinomycetes). Periodontal diseases have been linked to anaerobic Gram-negative bacteria forming a subgingival plaque (Porphyromonas gingivalis, Actinobacillus, Prevotella and Fusobacterium). Cells embedded in biofilm are up to 1000-fold more resistant to antibiotics compared to their planctonic ones. Several mechanisms have been proposed to explain biofilms drug resistance. Given the increased bacterial resistance to antibiotics currently used in dentistry, a great importance is given to natural compounds for the prevention of oral bacterial growth, adhesion and colonization. Over the past decade, interest in drugs derived from medicinal plants has markedly increased. It has been well documented that medicinal plants and natural compounds confer considerable antibacterial activity against various microorganisms including cariogenic and periodontal pathogens. This paper provides a review of the literature focusing on the studies on (i) biofilm in the oral cavity, (ii) drug resistance of bacterial biofilm and (iii) the potential use of plant extracts, essential oils and natural compounds as biofilm preventive agents in dentistry, involving their origin and their mechanism of biofilm inhibition.

Molecular detection of bacteria associated to dental caries in 4-12-year-old Tunisian children.

The occurrence of several microbial species in the oral cavity of 4-12-year-old Tunisian children was investigated. Samples were taken from 158 children (81 caries actives and 77 caries free). Genomic DNA was extracted and analyzed for the presence of 17 microbial species using a polymerase chain reaction assay. All samples were positive for at least one of the target microbial strains. Streptococcus mutans was the most prevalent species (76.5%) detected in genomic DNA collected from carious lesions. Other prevalent species were Candida spp (63%), Streptococcus salivarius (59%) and Streptococcus oralis (42%). The frequency of Lactobacillus acidophilus, Lactobacillus plantarum, and Lactobacillus casei-group in caries lesions was 29.5%, 34.5% and 22% respectively. Pathogenic bacteria such as Staphylococcus aureus was found in 28.5% of carious lesion samples compared to 15.5% in the control. Frequency of Porphyromonas endodontali, Actinomyces radicidentis and Treponema denticola recovery did not differ significantly between origins of samples. PCR analysis of genomic DNA detect various oral bacteria that differ between caries actives and caries-free children. In addition, the association of same aciduric bacteria (S. mutans, S. salivarius, L. acidophilus) and caries formation was noticed.

Detection of macrolide and disinfectant resistance genes in clinical Staphylococcus aureus and coagulase-negative staphylococci.

BACKGROUND: Staphylococcus aureus and Coagulase-negative staphylococci (CoNS) are a major source of infections associated with indwelling medical devices. Many antiseptic agents are used in hygienic handwash to prevent nosocomial infections by Staphylococci. Our aim was to determine the antibiotic susceptibility and resistance to quaternary ammonium compound of 46 S. aureus strains and 71 CoNS. METHODS: S. aureus (n = 46) isolated from auricular infection and CoNS (n = 71), 22 of the strains isolated from dialysis fluids and 49 of the strains isolated from needles cultures were investigated. Erythromycin resistance genes (ermA, ermB, ermC, msrA and mef) were analysed by multiplex PCR and disinfectant-resistant genes (qacA, qacB, and qacC) were studied by PCR-RFLP. RESULTS: The frequency of erythromycin resistance genes in S. aureus was: ermA+ 7.7%, ermB+ 13.7%, ermC+ 6% and msrA+ 10.2%. In addition, the number of positive isolates in CoNS was respectively ermA+ (9.4%), ermB+ (11.1%), ermC+ (27.4%), and msrA+ (41%). The MIC analyses revealed that 88 isolates (74%) were resistant to quaternary ammonium compound-based disinfectant benzalkonium chloride (BC). 56% of the BC-resistant staphylococcus isolates have at least one of the three resistant disinfectants genes (qacA, qacB and qacC). Nine strains (7.7%) among the CoNS species and two S. aureus strains (2%) harboured the three-qac genes. In addition, the qacC were detected in 41 strains. CONCLUSIONS: Multi-resistant strains towards macrolide and disinfectant were recorded. The investigation of antibiotics and antiseptic-resistant CoNS may provide crucial information on the control of nosocomial infections.