Adhesion and biofilm inhibiting properties of Chinese Herbal Formula SanHuang decoction against antibiotic resistant staphylococcal strains

Abstract Clinical study has shown that external socking and washing with the Chinese herbal SanHuang decoction (SH) can control the orthopedic-biofilm related infections. However, the antibiofilm activities of SH in vitro have not been investigated. The aim of the current study was to explore the effect of SH on adhesion and biofilm formation of antibiotic-resistant staphylococci on titanium surface, and to explore its probable mechanistic effects on staphylococcal strains. Biofilm-forming ATCC 35984 (methicillin-resistant Staphylococcus epidermidis, MRSE) and ATCC 43300 (methicillin-resistant Staphylococcus aureus, MRSA) strains were used in this study. The minimum inhibitory concentrations (MICs) of SH and vancomycin against planktonic bacterial strains were determined by the broth microdilution method. Different sub-MIC of SH with TSB (Tryptic soy broth) were used as the basis for experimental grouping (SH group). TSB culture medium alone (TSB group) or TSB containing vancomycin (vancomycin group) incubated with bacteria were considered as the negative or positive control group, respectively. The inhibitory effect of different treatment on bacterial adhesion and biofilm formation were observed by the spread plate method, CV (crystal violet) staining, scanning electron microscopy (SEM), and confocal laser scanning microscopy (CLSM). Real time PCR analysis was performed to determine the effect of SH on the expression levels of ica AD and ica R gene in ATCC 35984 during the biofilm formation. The strains were found to be susceptible to SH decoction with MIC and MBC values of 38.75 mg/ml and 77.5 mg/ml, respectively. The MIC values for vancomycin was 2.5 μg/ml. SH treatment with 1 MIC and 1/2 MIC could inhibit the bacteria adhesion on the titanium surface, showing only scattered bacterial adhesion from SEM. CLSM showed that SH with 1 MIC and 1/2 MIC could also inhibit the bacterial biofilm formation. The quantitative results of the spread plate method and CV staining showed that there was significant differences between the SH groups (P < 0.05). Further, with an increase in SH concentration, the inhibitory effect became more obvious at different culture time points, when compared with TSB control group (P < 0.05). Among the groups, vancomycin had the strongest inhibitory effect on bacterial adhesion and biofilm formation (P < 0.01). Meanwhile, with an increase in SH concentration, the expression levels of ica A and ica D decreased, and the expression of ica R increased correspondingly (P < 0.05). In conclusions, a certain concentration of SH can inhibit the adhesion and biofilm formation of antibiotic-resistant Staphylococcal strains on the titanium surface, but the effect was not as good as vancomycin. Its probable mechanistic activity may be through the inhibition of polysaccharide intercellular adhesin synthesis by down-regulating the expression of ica AD gene, thus inhibiting bacterial biofilm formation.

Download Full-text

Inhibitory properties of Chinese Herbal Formula SanHuang decoction on biofilm formation by antibiotic-resistant Staphylococcal strains

Scientific Reports ◽

10.1038/s41598-021-86647-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Shaoe Zhang ◽

Peizhao Wang ◽

Xiaotao Shi ◽

Honglue Tan

Keyword(s):

Bacterial Adhesion ◽

Biofilm Formation ◽

Inhibitory Effect ◽

Control Group ◽

Plate Method ◽

Antibiotic Resistant ◽

Expression Levels ◽

Chinese Herbal ◽

Broth Microdilution Method ◽

Sh Group

AbstractThe aim of this study was to explore the effect of Chinese herbal SanHuang decoction (SH) on biofilm formation of antibiotic-resistant Staphylococci on titanium surface, and to explore its mechanism. Biofilm-forming ATCC 35984, ATCC 43300 and MRSE 287 were used in this study. The MICs of SH and vancomycin against Staphylococci were determined by the broth microdilution method. Six groups were designed, namely control group (bacteria cultured with medium), 1/8MIC SH group (1MIC SH was diluted by 1/8 using TSB or saline), 1/4MIC SH group, 1/2MIC SH group, 1MIC SH group and vancomycin group (bacteria cultured with 1MIC vancomycin). The inhibitory effect on bacterial adhesion and biofilm formation were observed by the spread plate method, CV staining, SEM, and CLSM. Real-time PCR was performed to determine the effect of SH on the expression levels of ica AD and ica R gene in ATCC 35984 during the biofilm formation. The strains were found to be susceptible to SH and vancomycin with MIC of 38.75 mg/ml and 2.5 μg/ml, respectively. SH with 1 MIC and 1/2 MIC could inhibit the bacteria adhesion, showing only scattered adhesion from SEM. CLSM showed that SH with 1 MIC and 1/2 MIC inhibited the biofilm formation. The quantitative results of the spread plate method and CV staining showed that there was significant differences between the SH groups (P < 0.05). Further, with an increase in SH concentration, the inhibitory effect became more obvious when compared with control group. Among the groups, vancomycin had the strongest inhibitory effect on bacterial adhesion and biofilm formation (P < 0.01). With an increase in SH concentration, the expression levels of ica AD decreased, and the expression of ica R increased correspondingly (P < 0.05). In conclusions, SH can inhibit the biofilm formation of antibiotic-resistant Staphylococci. Its probable mechanistic activity may be through the inhibition of polysaccharide intercellular adhesin synthesis by down-regulating the expression of ica AD gene.

Download Full-text

A Real-Time Thermal Sensor System for Quantifying the Inhibitory Effect of Antimicrobial Peptides on Bacterial Adhesion and Biofilm Formation

Sensors ◽

10.3390/s21082771 ◽

2021 ◽

Vol 21 (8) ◽

pp. 2771

Author(s):

Tobias Wieland ◽

Julia Assmann ◽

Astrid Bethe ◽

Christian Fidelak ◽

Helena Gmoser ◽

...

Keyword(s):

Antimicrobial Peptides ◽

Real Time ◽

Bacterial Adhesion ◽

Biofilm Formation ◽

Pathogenic Bacteria ◽

Bovine Mastitis ◽

Inhibitory Effect ◽

Thermal Sensor ◽

Bacterial Cells ◽

Static Conditions

The increasing rate of antimicrobial resistance (AMR) in pathogenic bacteria is a global threat to human and veterinary medicine. Beyond antibiotics, antimicrobial peptides (AMPs) might be an alternative to inhibit the growth of bacteria, including AMR pathogens, on different surfaces. Biofilm formation, which starts out as bacterial adhesion, poses additional challenges for antibiotics targeting bacterial cells. The objective of this study was to establish a real-time method for the monitoring of the inhibition of (a) bacterial adhesion to a defined substrate and (b) biofilm formation by AMPs using an innovative thermal sensor. We provide evidence that the thermal sensor enables continuous monitoring of the effect of two potent AMPs, protamine and OH-CATH-30, on surface colonization of bovine mastitis-associated Escherichia (E.) coli and Staphylococcus (S.) aureus. The bacteria were grown under static conditions on the surface of the sensor membrane, on which temperature oscillations generated by a heater structure were detected by an amorphous germanium thermistor. Bacterial adhesion, which was confirmed by white light interferometry, caused a detectable amplitude change and phase shift. To our knowledge, the thermal measurement system has never been used to assess the effect of AMPs on bacterial adhesion in real time before. The system could be used to screen and evaluate bacterial adhesion inhibition of both known and novel AMPs.

Download Full-text

Inducible Clindamycin Resistance and Biofilm Production among Staphylococci Isolated from Tertiary Care Hospitals in Nepal

Infectious Disease Reports ◽

10.3390/idr13040095 ◽

2021 ◽

Vol 13 (4) ◽

pp. 1043-1052

Author(s):

Sarita Manandhar ◽

Raju Shrestha ◽

Ratna Shova Tuladhar ◽

Sunil Lekhak

Keyword(s):

Tissue Culture ◽

Biofilm Formation ◽

Tertiary Care ◽

Plate Method ◽

Methicillin Resistant ◽

Inducible Clindamycin Resistance ◽

Biofilm Production ◽

Resistant Strains ◽

Tissue Culture Plate ◽

Tertiary Care Hospitals

Resistance to antibiotics, biofilm formation and the presence of virulence factors play important roles in increased mortality associated with infection by staphylococci. The macrolide lincosamide streptogramin B (MLSB) family of antibiotics is commonly used to treat infections by methicillin-resistant isolates. Clinical failure of clindamycin therapy has been reported due to multiple mechanisms that confer resistance to MLSB. This study aims to find the incidence of different phenotypes of MLSB resistance and biofilm production among staphylococci. A total of 375 staphylococci were isolated from different clinical samples, received from two tertiary care hospitals in Nepal. Methicillin resistance was detected by cefoxitin disc diffusion method and inducible clindamycin resistance by D test, according to CLSI guidelines. Biofilm formation was detected by the tissue culture plate method and PCR was used to detect ica genes. Of the total staphylococci isolates, 161 (42.9%) were Staphylococcus aureus, with 131 (81.4%) methicillin-resistant strains, and 214 (57.1%) isolates were coagulase-negative staphylococci, with 143 (66.8%) methicillin-resistant strains. The overall prevalence of constitutive MLSB (cMLSB) and inducible MLSB (iMLSB) phenotypes was 77 (20.5%) and 87 (23.2%), respectively. Both iMLSB and cMLSB phenotypes predominated in methicillin-resistant isolates. The tissue culture plate method detected biofilm formation in 174 (46.4%) isolates and ica genes in 86 (22.9%) isolates. Among biofilm producing isolates, cMLSB and iMLSB phenotypes were 35 (20.1%) and 27 (15.5%), respectively. The cMLSB and iMLSB were 11 (12.8%) and 19 (22.1%), respectively, in isolates possessing ica genes. Clindamycin resistance in the form of cMLSB and iMLSB, especially among MRSA, emphasizes the need for routine D tests to be performed in the lab.

Download Full-text

Virulence of methicillin-resistant Staphylococcus aureus modulated by the YycFG two-component pathway in a rat model of osteomyelitis

Journal of Orthopaedic Surgery and Research ◽

10.1186/s13018-019-1508-z ◽

2019 ◽

Vol 14 (1) ◽

Author(s):

Shizhou Wu ◽

Yunjie Liu ◽

Lei Lei ◽

Hui Zhang

Keyword(s):

Staphylococcus Aureus ◽

Western Blot ◽

Rat Model ◽

Biofilm Formation ◽

Bacterial Biofilm ◽

Invasive Ability ◽

Methicillin Resistant ◽

Two Component ◽

Mrsa Strains

Abstract Objectives Methicillin-resistant Staphylococcus aureus (MRSA) strains present an urgent medical problem in osteomyelitis cases. Our previous study indicated that the YycFG two-component regulatory pathway is associated with the bacterial biofilm organization of MRSA strains. The aim of this study was to investigate the regulatory roles of ASyycG in the bacterial biofilm formation and the pathogenicity of MRSA strains using an antisense RNA strategy. Methods An ASyycG-overexpressing MRSA clinical isolate was constructed. The bacterial growth was monitored, and the biofilm biomass on bone specimens was examined using scanning electron microscopy and confocal laser scanning microscopy. Furthermore, quantitative RT-PCR (QRT-PCR) analysis was used to measure the expression of yycF/G/H and icaA/D in the MRSA and ASyycG strains. The expression of the YycG protein was quantified by Western blot assays. We validated the role of ASyycG in the invasive ability and pathogenicity of the strains in vivo using histology and peptide nucleic acid fluorescent in situ hybridization. Results The results showed that overexpression of ASyycG lead to a reduction in biofilm formation and exopolysaccharide (EPS) synthesis compared to the control MRSA strains. The ASyycG strains exhibited decreased expression of the yycF/G/H and icaA/D genes. Furthermore, Western blot data showed that the production of the YycG protein was inhibited in the ASyycG strains. In addition, we demonstrated that ASyycG suppressed the invasive ability and pathogenicity of the strain in vivo using an SPF (specific pathogen free) rat model. Conclusion In summary, the overexpression of ASyycG leads to a reduction in biofilm formation and bacterial pathogenicity in vivo, which provides a potential target for the management of MRSA-induced osteomyelitis.

Download Full-text

Effect of vancomycin-coated tympanostomy tubes on methicillin-resistant Staphylococcus aureus biofilm formation: in vitro study

The Journal of Laryngology & Otology ◽

10.1017/s0022215109992672 ◽

2010 ◽

Vol 124 (6) ◽

pp. 594-598 ◽

Cited By ~ 16

Author(s):

C H Jang ◽

H Park ◽

Y B Cho ◽

C H Choi

Keyword(s):

Staphylococcus Aureus ◽

Biofilm Formation ◽

Silver Oxide ◽

In Vitro Study ◽

Bacterial Biofilm ◽

Tube Placement ◽

Tympanostomy Tube ◽

Methicillin Resistant ◽

Tympanostomy Tubes

AbstractBackground and objective:Bacterial biofilm formation has been implicated in the high incidence of persistent otorrhoea after tympanostomy tube insertion. It has been suggested that the tube material may be an important factor in the persistence of such otorrhoea. Development of methicillin-resistant Staphylococcus aureus otorrhoea after tympanostomy tube placement is a growing concern. We evaluated the effect of using vancomycin and chitosan coated tympanostomy tubes on the incidence of methicillin-resistant Staphylococcus aureus biofilm formation in vitro.Materials and methods:Three sets each of vancomycin-coated silicone tubes (n = 5), commercial silver oxide coated silicone tubes (n = 5) and uncoated tympanostomy tubes (as controls; n = 5) were compared as regards resistance to methicillin-resistant Staphylococcus aureus biofilm formation after in vitro incubation.Results:Scanning electron microscopy showed that the surfaces of the silver oxide coated tubes supported the formation of thick biofilms with crusts, comparable to the appearance of the uncoated tubes. In contrast, the surface of the vancomycin-coated tympanostomy tubes was virtually devoid of methicillin-resistant Staphylococcus aureus biofilm.Conclusion:Vancomycin-coated tympanostomy tubes resist methicillin-resistant Staphylococcus aureus biofilm formation. Pending further study, such tubes show promise in assisting the control of methicillin-resistant Staphylococcus aureus biofilm formation.

Download Full-text

N-Acetyl-l-Cysteine Affects Growth, Extracellular Polysaccharide Production, and Bacterial Biofilm Formation on Solid Surfaces

Applied and Environmental Microbiology ◽

10.1128/aem.69.8.4814-4822.2003 ◽

2003 ◽

Vol 69 (8) ◽

pp. 4814-4822 ◽

Cited By ~ 133

Author(s):

Ann-Cathrin Olofsson ◽

Malte Hermansson ◽

Hans Elwing

Keyword(s):

Stainless Steel ◽

Bacterial Adhesion ◽

Biofilm Formation ◽

Paper Mill ◽

Bacterial Biofilm ◽

Extracellular Polysaccharides ◽

Positive Effects ◽

Initial Adhesion ◽

Interesting Candidate ◽

Steel Surfaces

ABSTRACT N-Acetyl-l-cysteine (NAC) is used in medical treatment of patients with chronic bronchitis. The positive effects of NAC treatment have primarily been attributed to the mucus-dissolving properties of NAC, as well as its ability to decrease biofilm formation, which reduces bacterial infections. Our results suggest that NAC also may be an interesting candidate for use as an agent to reduce and prevent biofilm formation on stainless steel surfaces in environments typical of paper mill plants. Using 10 different bacterial strains isolated from a paper mill, we found that the mode of action of NAC is chemical, as well as biological, in the case of bacterial adhesion to stainless steel surfaces. The initial adhesion of bacteria is dependent on the wettability of the substratum. NAC was shown to bind to stainless steel, increasing the wettability of the surface. Moreover, NAC decreased bacterial adhesion and even detached bacteria that were adhering to stainless steel surfaces. Growth of various bacteria, as monocultures or in a multispecies community, was inhibited at different concentrations of NAC. We also found that there was no detectable degradation of extracellular polysaccharides (EPS) by NAC, indicating that NAC reduced the production of EPS, in most bacteria tested, even at concentrations at which growth was not affected. Altogether, the presence of NAC changes the texture of the biofilm formed and makes NAC an interesting candidate for use as a general inhibitor of formation of bacterial biofilms on stainless steel surfaces.

Download Full-text

Composition Analysis and Inhibitory Effect ofSterculia lychnophoraagainst Biofilm Formation byStreptococcus mutans

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2016/8163150 ◽

2016 ◽

Vol 2016 ◽

pp. 1-9 ◽

Cited By ~ 2

Author(s):

Yang Yang ◽

Bok-Im Park ◽

Eun-Hee Hwang ◽

Yong-Ouk You

Keyword(s):

Biofilm Formation ◽

Ethanol Extract ◽

Inhibitory Effect ◽

Significant Inhibition ◽

Control Group ◽

Composition Analysis ◽

Phytochemical Analysis ◽

Chinese Drug ◽

Nutrient Contents ◽

Ethanol Extracts

Pangdahai is a traditional Chinese drug, specifically described in the Chinese Pharmacopoeia as the seeds ofSterculia lychnophoraHance. Here, we separatedS. lychnophorahusk and kernel, analyzed the nutrient contents, and investigated the inhibitory effects ofS. lychnophoraethanol extracts on cariogenic properties ofStreptococcus mutans, important bacteria in dental caries and plaque formation. Ethanol extracts ofS. lychnophorashowed dose-dependent antibacterial activity againstS. mutanswith significant inhibition at concentrations higher than 0.01 mg/mL compared with the control group (p<0.05). Furthermore, biofilm formation was decreased byS. lychnophoraat concentrations > 0.03 mg/mL, while bacterial viability was decreased dose-dependently at high concentrations (0.04, 0.08, 0.16, and 0.32 mg/mL). Preliminary phytochemical analysis of the ethanol extract revealed a strong presence of alkaloid, phenolics, glycosides, and peptides while the presence of steroids, terpenoids, flavonoids, and organic acids was low. TheS. lychnophorahusk had higher moisture and ash content than the kernel, while the protein and fat content of the husk were lower (p<0.05) than those of the kernel. These results indicate thatS. lychnophoramay have antibacterial effects againstS. mutans, which are likely related to the alkaloid, phenolics, glycosides, and peptides, the major components ofS. lychnophora.

Download Full-text

Biofilm Formation in Methicillin-Resistant Staphylococcus aureus Isolated in Cystic Fibrosis Patients Is Strain-Dependent and Differentially Influenced by Antibiotics

Frontiers in Microbiology ◽

10.3389/fmicb.2021.750489 ◽

2021 ◽

Vol 12 ◽

Author(s):

Agathe Boudet ◽

Pauline Sorlin ◽

Cassandra Pouget ◽

Raphaël Chiron ◽

Jean-Philippe Lavigne ◽

...

Keyword(s):

Cystic Fibrosis ◽

Staphylococcus Aureus ◽

Biofilm Formation ◽

Multidrug Resistant ◽

Inhibitory Effect ◽

Ring Test ◽

Methicillin Resistant ◽

Lung Dysfunction ◽

Chronic Colonization ◽

Strain Dependent

Cystic fibrosis (CF) is a genetic disease with lung abnormalities making patients particularly predisposed to pulmonary infections. Staphylococcus aureus is the most frequently identified pathogen, and multidrug-resistant strains (MRSA, methicillin-resistant S. aureus) have been associated with more severe lung dysfunction leading to eradication recommendations. Diverse bacterial traits and adaptive skills, including biofilm formation, may, however, make antimicrobial therapy challenging. In this context, we compared the ability of a collection of genotyped MRSA isolates from CF patients to form biofilm with and without antibiotics (ceftaroline, ceftobiprole, linezolid, trimethoprim, and rifampicin). Our study used standardized approaches not previously applied to CF MRSA, the BioFilm Ring test® (BRT®), the Antibiofilmogram®, and the BioFlux™ 200 system which were adapted for use with the artificial sputum medium (ASM) mimicking conditions more relevant to the CF lung. We included 63 strains of 10 multilocus sequence types (STs) isolated from 35 CF patients, 16 of whom had chronic colonization. The BRT® showed that 27% of the strains isolated in 37% of the patients were strong biofilm producers. The Antibiofilmogram® performed on these strains showed that broad-spectrum cephalosporins had the lowest minimum biofilm inhibitory concentrations (bMIC) on a majority of strains. A focus on four chronically colonized patients with inclusion of successively isolated strains showed that ceftaroline, ceftobiprole, and/or linezolid bMICs may remain below the resistance thresholds over time. Studying the dynamics of biofilm formation by strains isolated 3years apart in one of these patients using BioFlux™ 200 showed that inhibition of biofilm formation was observed for up to 36h of exposure to bMIC and ceftaroline and ceftobiprole had a significantly greater effect than linezolid. This study has brought new insights into the behavior of CF MRSA which has been little studied for its ability to form biofilm. Biofilm formation is a common characteristic of prevalent MRSA clones in CF. Early biofilm formation was strain-dependent, even within a sample, and not only observed during chronic colonization. Ceftaroline and ceftobiprole showed a remarkable activity with a long-lasting inhibitory effect on biofilm formation and a conserved activity on certain strains adapted to the CF lung environment after years of colonization.

Download Full-text

Disrupting Irreversible Bacterial Adhesion and Biofilm Formation with an Engineered Enzyme

Applied and Environmental Microbiology ◽

10.1128/aem.00265-21 ◽

2021 ◽

Author(s):

Holly M. Mayton ◽

Sharon L. Walker ◽

Bryan W. Berger

Keyword(s):

Listeria Monocytogenes ◽

Bacterial Adhesion ◽

Biofilm Formation ◽

Glycosyl Hydrolase ◽

Cell Surface Hydrophobicity ◽

Bacterial Biofilm ◽

Enzyme Treatment ◽

E Coli ◽

Initial Adhesion ◽

The Impact

Biofilm formation is often attributed to post-harvest bacteria persistence on fresh produce and food handling surfaces. In this study, a predicted glycosyl hydrolase enzyme was expressed, purified and validated for removal of microbial biofilms from biotic and abiotic surfaces under conditions used for chemical cleaning agents. Crystal violet biofilm staining assays revealed that 0.1 mg/mL of enzyme inhibited up to 41% of biofilm formation by E. coli O157:H7, E. coli 25922, Salmonella Typhimurium, and Listeria monocytogenes. Further, the enzyme was effective at removing mature biofilms, providing a 35% improvement over rinsing with a saline solution alone. Additionally, a parallel-plate flow cell was used to directly observe and quantify the impact of enzyme rinses on E. coli O157:H7 cells adhered to spinach leaf surfaces. The presence of 1 mg/L enzyme resulted in nearly 6 times greater detachment rate coefficients than a DI water rinse, while the total cells removed from the surface increased from 10% to 25% over the 30 minute rinse time, reversing the initial phases of biofilm formation. Enzyme treatment of all 4 cell types resulted in significantly reduced cell surface hydrophobicity, and collapse of negatively stained E. coli 25922 cells imaged by electron microscopy, suggesting potential polysaccharide surface modification of enzyme-treated bacteria. Collectively, these results point to the broad substrate specificity and robustness of the enzyme to different types of biofilm stages, solution conditions and pathogen biofilm types, and may be useful as a method for removal or inhibition of bacterial biofilm formation. IMPORTANCE In this study, the ability of an engineered enzyme to reduce bacterial adhesion and biofilm formation of several foodborne pathogens was demonstrated, representing a promising option for enhancing or replacing chlorine and other chemical sanitizers in food processing applications. Specifically, significant reductions of the pathogens Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes biofilms are observed, as well as reduction in initial adhesion. Enzymes have the added benefits of being green, sustainable alternatives to chemical sanitizers, as well as having minimal impact on food properties, in contrast with many alternative antimicrobial options such as bleach that aim to minimize food safety risks.

Download Full-text

Eradication of a Mature Methicillin-Resistant Staphylococcus aureus (MRSA) Biofilm From Acrylic Surfaces

Brazilian Dental Journal ◽

10.1590/0103-6440201302289 ◽

2013 ◽

Vol 24 (5) ◽

pp. 487-491 ◽

Cited By ~ 10

Author(s):

Karen Tereza Altieri ◽

Paula Volpato Sanitá ◽

Ana Lucia Machado ◽

Eunice Teresinha Giampaolo ◽

Ana Cláudia Pavarina ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Microwave Irradiation ◽

Sodium Hypochlorite ◽

Biofilm Formation ◽

Methicillin Resistant Staphylococcus Aureus ◽

Acrylic Resin ◽

Positive Control ◽

Chlorhexidine Gluconate ◽

Control Group ◽

Methicillin Resistant

Methicillin-resistant Staphylococcus aureus (MRSA) can grow as structured biofilm in different surfaces, including oral mucosa and denture surfaces. Such biofilms can be released into the oral fluids and aspirated, causing systemic infections such as aspiration pneumonia. This study evaluated the efficacy of two disinfectant solutions and microwave irradiation in disinfecting acrylic specimens contaminated with MRSA biofilm. Thirty-six acrylic specimens were made, sterilized and contaminated with MRSA (107 cfu/mL). After incubation (37 °C/48 h), the specimens were divided into 4 groups: not disinfected (positive control); soaking in 1% sodium hypochlorite for 10 min; soaking in 2% chlorhexidine gluconate for 10 min; and irradiating by microwave for 3 min at 650 W. The viability of cells was evaluated by XTT reduction method. All specimens from the positive control group showed biofilm formation after 48 h incubation. The mean absorbance value of the control specimens was 1.58 (OD at 492 nm). No evidence of biofilm formation was observed on specimens after the disinfection methods. Disinfection by soaking in 1% sodium hypochlorite and 2% chlorhexidine gluconate and irradiating by microwaves resulted in 100% reduction of MRSA biofilm metabolism. The use of chemical solutions and microwave irradiation was shown to be effective for eradicating mature MRSA biofilms on acrylic resin specimens.

Download Full-text