Minimum Biofilm Eradication Concentration Research Articles

Antibiofilm Activity and Synergistic Effects of Thymol-Loaded Poly (Lactic-Co-Glycolic Acid) Nanoparticles with Amikacin against Four Salmonella enterica Serovars.

Salmonella species are frequently linked to biofilm-associated infections. Biofilm formation intensively reduces the efficacy of antibiotics and the host immune system. Therefore, new therapeutic strategies are needed. Thymol, the main monoterpene phenol found in Thymus vulgaris, has been shown to possess potent antibiofilm activity. Our previous findings showed that thymol enhanced the antibiofilm activity of aminoglycosides against Salmonella enterica serovars. However, the clinical potential of thymol has not yet been realized due to its low aqueous solubility and high volatility. Nano-based drug delivery systems have emerged as a novel strategy to resolve these problems. This study aimed to investigate the antibiofilm activity of thymol-loaded poly (lactic-co-glycolic acid) nanoparticles (TH-NPs) and their synergism when used in combination with amikacin antibiotics. The antibacterial activity of TH-NPs was evaluated using the broth microdilution method. Biofilm formation and antibiofilm assays were performed by the miniaturized microtiter plate method. Interaction studies between TH-NPs and amikacin against biofilm were determined using the checkerboard method. TH-NPs exhibited antibacterial activity against planktonic cells of S. enterica serovars that were more efficient (8 to 32 times) than free thymol alone. S. Typhimurium and S. Choleraesuis isolates were considered strong biofilm producers. The combination of TH-NPs with amikacin showed synergistic activity in the inhibition and eradication of S. enterica serovar biofilm. The minimum biofilm inhibitory concentration (MBIC) and minimum biofilm eradication concentration (MBEC) of amikacin were reduced by 32 to 128-fold when used in combination with TH-NPs. Time-kill kinetic studies showed that the combination of TH-NPs with amikacin possesses bactericidal action. This study suggests that the combination of TH-NPs with amikacin can be an alternative to overcome biofilm-associatedSalmonella diseases and therefore should be further explored as a model to search for new antibiofilm drugs.

Exploration of a W/O Nanoemulsion for Antibiofilm Activity against Cariogenic Enterococcus faecalis.

A ciprofloxacin-loaded water-in-oil nanoemulsion (CPX-NE) was prepared and evaluated for the antimicrobial effect against oral biofilms produced by Enterococcus faecalis. CPX-NE was prepared by ultrasonication using functional excipients oleic acid (oil phase), Span 80 (surfactant), and Transcutol P (cosurfactant). Rheological parameters (viscosity = 20 ± 1.24 cp) confirmed optimum values for CPX-NE, a pH of 6.5 ± 0.23 suggested the simulation of CPX-NE with the pH of the mouth cavity, refractive index (1.46 ± 0.22), and % transmittance (92.34 ± 0.02) indicated the isotropic nature of the NE. The droplet size (72.19 ± 1.68 nm), polydispersity index (0.142 ± 0.02), and ζ potential (-28 mV) demonstrated a narrow size distribution and electrostatically stabilized NE. The morphology of the optimized formulation showed uniform spherical nanodroplets, as seen in fluorescence microscopy. In vitro drug release showed an initial burst effect followed by sustained release for 48 h, following Fick's diffusion. The minimum biofilm inhibitory and eradication concentration (MBIC/MBEC) was determined to compare CPX-NE with ciprofloxacin plain drug solution (CPX-PS) for their efficacy. CPX-NE demonstrated a significant inhibitory and eradication effect compared to CPX-PS. It was concluded that the developed CPX-NE has effective antibiofilm activity against E. faecalis and may be useful in the prevention and treatment of dental caries.

Antibacterial and Anti-biofilm Efficiency of Twenty Algerian Plants Essential Oils Against Resistant Acinetobacter baumannii

The present study evaluated the antibacterial activity of twenty essential oils from Algerian plants against the multi-drug resistant (MDR), the extended-drug resistant (XDR), the pan-drug resistant (PDR) and the wild strains of Acinetobacter baumannii: a major human pathogen for which only a few effective treatments are nowadays available. Special attention was also given to their effect on A. baumannii biofilm formation. The chemical composition of the essential oils was determined by gas chromatography and gas chromatography-mass spectrometry analysis, while the antibacterial activity was determined by disc diffusion and microdilution broth sensitivity assays. Microscopic visualization highlighted the effect of the most active essential oils on biofilm formation. Molecular docking was performed to investigate the binding mode of imipenem, thymol and cinnamaldehyde against target proteins (PBP1, OMPA and IMP2). Eight of the twenty essential oils showed very good activities against resistant A.baumannii with inhibition zones greater than 20 mm. Ammoides verticillata essential oil recorded the lowest minimum inhibitory concentrations, biofilm inhibition and biofilm eradication concentrations values no more than 0.217 mg/mL, 0.48 mg/mL, and 0.48 mg/mL, respectively. A. verticillata and C. cassia not only inhibited biofilm formation but also weakened and dissolved pre-formed biofilms. The in-silico and in-vitro studies showed that phytochemical analogues, thymol and cinnamaldehyde had improved physicochemical characteristics, greater binding affinities and, a better anti-Acinetobacter activity comapared to imipenem. The results of this study suggest that essential oils and their individual components can be used as therapeutic substances and as cleaning products since they are effective and eco-friendly.

Bioactivity Tracing of the Ethanol Extract of Bajakah Tampala (Spatholobus littoralis Hassk.) Typical Plant of Kalimantan Island as Antibiofilm of Staphylococcus aureus

BACKGROUND: Free radicals (oxidants) can cause skin irritation/damage which can be a manifestation of minor skin infections. Not only that, one of the complications of the disease that can arise is diabetes mellitus (DM) with diabetic foot ulcers (LKD). LKD is very susceptible to exposure to microorganisms and develops into diabetic foot infection (DFI). DFI is associated with the presence of biofilms in wounds especially those caused by Staphylococcus aureus infection. Bajakah tampala (Spatholobus littoralis hassk) is one of the native plants of Indonesia which has been known to have antibacterial activity, while its antibiofilm activity has not been studied. Evaluation of antibiofilms from the tampala bajakah plant can be of good novelty value, as well as support success in the treatment of infectious. AIM: This study aims to determine the effectiveness of the ethanol extract of the Bajakah tampala plant from East Kalimantan in inhibiting and eradicating the formation of S. aureus biofilms. MATERIALS AND METHODS: The planktonic and biofilm inhibition tests were carried out using the microtiter broth method. Antibiofilm activity of Bajakah tampala ethanol extract against S. aureus was analyzed by calculating the minimum biofilm inhibitor concentration (MBIC50) and the biofilm eradication activity calculating the minimum biofilm eradication concentration (MBEC50). In addition, we also carried out additional verification tests using the DPPH method by calculating the inhibitory concentration (IC50) parameter value. RESULTS: The results showed that the 1% bajakah tampala extract gave mid-phase antibiofilm activity of 80.23% w/v ± 0.01, maturation phase of 77.23% w/v ± 0.01 and eradication with a large inhibition of 75.56% w/v ± 0.01. In the DPPH test, the IC50 value was 5.9 ppm with a very strong category. CONCLUSION: Thus, it can be concluded that the ethanolic extract of the Bajakah tampala plant has a high potential to be developed as a candidate for new antibiofilm drugs against S. aureus biofilms.

Effect of Cymbopogon citratus on biofilm production by multidrug resistant Acinetobacter baumannii

Introduction and Aim: Acinetobacter baumannii, is the cause of many nosocomial infections which poses a serious threat to patients. Being a highly resistant organism, it has been placed in the critical priority list by WHO in 2017, thereby requiring newer effective drugs and alternative strategies. Increased antibiotic resistance has made it difficult to treat patients infected with this organism. The study aimed to find the biofilm forming ability of multidrug resistant A.baumannii causing respiratory tract infections, to find the genes responsible for biofilm production and to find the effect of Cymbopogon citratus (lemon grass) extract on biofilm. Materials and Methods: The antibiogram profile was studied for the Acinetobacter isolates obtained from endotracheal aspirates, endotracheal tubing tips by antibiotic susceptibility testing and Vitek-2. Genes known to be associated with biofilm production, (AbOmpA, Bap) in Acinetobacter were detected by Polymerase chain reaction (PCR). The Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), Minimum Biofilm Inhibitory Concentration (MBIC), Minimum Biofilm Eradication Concentration (MBEC) of Cymbopogon citratus essential oil was determined by microtiter plate method. Results: Isolates that were tested were found to be Multidrug resistant (MDR) and Extremely drug resistant (XDR) with highest resistance to Carbapenems (95.83%). Activity of Cymbopogon citratus EO was determined. The isolates predominantly showed MIC of 2% and MBC was 8%. MBIC was found to be 1%. However, Cymbopogon citratus EO did not eradicate the preformed biofilms. All 24 isolates showed AbOmpA gene and six showed presence of Bap gene. Conclusion: This study demonstrated that isolates that produced the Bap gene were Extremely drug resistant (XDR). Biofilm formation was inhibited by Lemongrass essential oil (EO) but it did not eradicate the preformed biofilms.

Biofilm and pathogenic factor analysis of Gardnerella vaginalis associated with bacterial vaginosis in Northeast China.

Gardnerella vaginalis is a major pathogen responsible for bacterial vaginosis (BV). However, the recurrence of infection and the antibiotic resistance of biofilms remain significant challenges for the treatment of BV. In this study, we aimed to analyze the pathogenic factors and drug sensitivity associated with the clinical treatment of BV in Northeast China. Subgroups were identified by clade-specific polymerase chain reaction (PCR). Biofilm formation was measured by crystal violet staining, confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). The inhibition and eradication of biofilm formation were measured by XTT and broth recovery-based methods. Of the 24 samples of G. vaginalis, 11 samples and American Type Culture Collection (ATCC) 14018 formed biofilms; the remainder did not. The positive rates of detection for the sialidase A and vly genes in the 24 G. vaginalis samples were 100% and 79.2%, respectively. Moreover, 21 samples (87.5%) showed resistance to metronidazole and 16 (66.7%) presented with sensitivity towards clindamycin. The biofilm MIC80 (BMIC80) of metronidazole for ATCC14018 was 16 μg/ml while that of clindamycin was 0.125 μg/ml. The minimum biofilm eradication concentration (MBEC) of metronidazole was > 256 μg/ml while that of clindamycin was > 2 μg/ml. Our results revealed that G. vaginalis is more resistant to metronidazole than clindamycin and neither metronidazole nor clindamycin are able to effectively eradicate vaginal biofilms. Thus, the role of antibiotics and biofilms in BV requires further investigation.

Antimicrobial and Antibiofilm Effects of Combinatorial Treatment Formulations of Anti-Inflammatory Drugs-Common Antibiotics against Pathogenic Bacteria.

With the spread of multi-drug-resistant (MDR) bacteria and the lack of effective antibiotics to treat them, developing new therapeutic methods and strategies is essential. In this study, we evaluated the antibacterial and antibiofilm activity of different formulations composed of ibuprofen (IBP), acetylsalicylic acid (ASA), and dexamethasone sodium phosphate (DXP) in combination with ciprofloxacin (CIP), gentamicin (GEN), cefepime (FEP), imipenem (IPM), and meropenem (MEM) on clinical isolates of Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) as well as the transcription levels of biofilm-associated genes in the presence of sub-MICs of IBP, ASA, and DXP. The minimal inhibitory concentrations (MICs), minimal biofilm inhibitory concentrations (MBICs), and minimum biofilm eradication concentrations (MBECs) of CIP, GEN, FEP, IPM, and MEM with/without sub-MICs of IBP (200 µg/mL), ASA (200 µg/mL), and DXP (500 µg/mL) for the clinical isolates were determined by the microbroth dilution method. Quantitative real-time-PCR (qPCR) was used to determine the expression levels of biofilm-related genes, including icaA in S. aureus and algD in P. aeruginosa at sub-MICs of IBP, ASA, and DXP. All S. aureus isolates were methicillin-resistant S. aureus (MRSA), and all P. aeruginosa were resistant to carbapenems. IBP decreased the levels of MIC, MBIC, and MBEC for all antibiotic agents in both clinical isolates, except for FEP among P. aeruginosa isolates. In MRSA isolates, ASA decreased the MICs of GEN, FEP, and IPM and the MBICs of IPM and MEM. In P. aeruginosa, ASA decreased the MICs of FEP, IPM, and MEM, the MBICs of FEP and MEM, and the MBEC of FEP. DXP increased the MICs of CIP, GEN, and FEP, and the MBICs of CIP, GEN, and FEP among both clinical isolates. The MBECs of CIP and FEP for MRSA isolates and the MBECs of CIP, GEN, and MEM among P. aeruginosa isolates increased in the presence of DXP. IBP and ASA at 200 µg/mL significantly decreased the transcription level of algD in P. aeruginosa, and IBP significantly decreased the transcription level of icaA in S. aureus. DXP at 500 µg/mL significantly increased the expression levels of algD and icaA genes in S. aureus and P. aeruginosa isolates, respectively. Our findings showed that the formulations containing ASA and IBP have significant effects on decreasing the MIC, MBIC, and MBEC levels of some antibiotics and can down-regulate the expression of biofilm-related genes such as icaA and algD. Therefore, NSAIDs represent appropriate candidates for the design of new antibacterial and antibiofilm therapeutic formulations.

Evaluation of the Efficacy of Organic Peroxyacids for Eradicating Dairy Biofilms Using an Approach Combining Static and Dynamic Methods.

The presence of biofilms in the dairy industry is of major concern, as they may lead to the production of unsafe and altered dairy products due to their high resistance to most clean-in-place (CIP) procedures frequently used in processing plants. Therefore, it is imperative to develop new biofilm control strategies for the dairy industry. This protocol is aimed at evaluating the efficacy of organic peroxyacids (peracetic, perpropionic, and perlactic acids and a commercial peracetic acid-based disinfectant) for eradicating dairy biofilms using a combination of static and dynamic methods. All the disinfectants were tested on the strongest biofilm-producing bacteria in either a single or a mixed biofilm using the minimum biofilm eradication concentration (MBEC) assay, a static high-throughput screening method. A contact time of 5 min with the disinfectants at the recommended concentrations successfully eradicated both the single and mixed biofilms. Studies are currently ongoing to confirm these observations using the Center for Disease Control (CDC) biofilm reactor, a dynamic method to mimic in situ conditions. This type of bioreactor enables the use of a stainless-steel surface, which constitutes most industrial equipment and surfaces. The preliminary results from the reactor appear to confirm the efficacy of organic peroxyacids against biofilms. The combined approach described in this study may be used to develop and test new biological or chemical formulations for controlling biofilms and eradicating microorganisms.

Anti-Biofilm Effect of Bacteriophages and Antibiotics against Uropathogenic Escherichia coli.

Escherichia coli is a common cause of biofilm-associated urinary tract infections. Bacteria inside the biofilm are more resistant to antibiotics. Six E. coli strains isolated from patients with urinary tract infections were screened for biofilm-forming capability and antimicrobial susceptibility. Two of the most significant biofilm-producing strains were selected for minimal inhibitory concentration and minimal biofilm eradication concentration in vitro testing using amoxicillin-clavulanic acid, ciprofloxacin, and three commercial bacteriophage cocktails (Pyobacteriophag, Ses, and Intesti). In case of a low phage effect, an adaptation procedure was performed. Although the biofilms formed by strain 021UR were resistant to amoxicillin-clavulanic acid and ciprofloxacin, the three phage cocktails were able to reduce biofilm formation. In contrast, phages did not affect the 01206UR strain against planktonic and biofilm-forming cells. After Pyobacteriophag adaptation, the effect improved, and, regardless of the concentration, the adapted phage cocktail could destroy both planktonic cells and the biofilm of strain 01206UR. Bacteriophages capable of killing bacteria in biofilms can be used as an alternative to antibiotics. However, each case should be considered individually due to the lack of clinical trials for phage therapy. Antimicrobial and phage susceptibility should be determined in biofilm models before treatment to achieve the desired anti-biofilm effect.

Efficacy of Propolis Gel on Mature Biofilm Formed by Neocosmospora keratoplastica Isolated from Onychomycosis.

This article describes Neocosmospora keratoplastica as an etiological onychomycosis agent. Ex vivo studies were initially performed to demonstrate the ability of this species to grow and form a well-organized characteristic biofilm on sterilized healthy nails. Based on the history of excellent results, both for antifungal and antibiofilm, of propolis resin gum, we evaluated its activity using artificially formed biofilm. In vitro, the minimal biofilm eradication concentration of the propolis extract (PE) was 375 µg of total polyphenol content (TPC) per mL, while for the propolis gel (PG) it was 450 µg of TPC per mL. In biofilm exposed to the propolis products, a decrease in hyphae and conidia was evident, accompanied by a disorganization of the extracellular matrix. Additionally, this low concentration of PE was able to significantly reduce the number of colony-forming units and the metabolic activity. Furthermore, the treatment of a 15-year nail infection due to N. keratoplastica was carried out exclusively using a topical treatment with a gel containing propolis (30%) with a daily dosage. This treatment achieved complete remission of the onychomycosis in 12 months. It is important to point out that some inconveniences previously reported by other patients treated with propolis extract were eliminated, increasing adherence to treatment.

TA-AgNPs/Alginate Hydrogel and Its Potential Application as a Promising Antibiofilm Material against Polymicrobial Wound Biofilms Using a Unique Biofilm Flow Model.

The presence of biofilm within a chronic wound may delay the healing process. Thus, control of biofilm formation and providing bactericidal effect are crucial factors for wound healing management. Alginate-based nanocomposite hydrogels have been suggested as dressing materials for wound treatment, which are employed as a biocompatible matrix. Therefore, in this study, we aimed to develop a biocompatible antimicrobial wound dressing containing AgNPs and demonstrate its efficacy against polymicrobial wound biofilms by using a biofilm flow device to simulate a chronic infected, exuding wound and specific wound environment. The results from agar well diffusion, the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) assays showed that TA-AgNPs exhibited antibacterial activity against wound pathogens. Additionally, the Minimum Biofilm Eradication Concentration assay (MBEC) demonstrated it could impair biofilm formation. Importantly, our TA-AgNPs/Alginate hydrogel clearly showed antibacterial activities against Streptococcus pyogenes, Staphylococcus aureus and Pseudomonas aeruginosa. Furthermore, we used the biofilm flow device to test the topical antimicrobial hydrogel against a three-species biofilm. We found that TA-AgNPs/Alginate hydrogel significantly showed a 3-4 log reduction in bacterial numbers when applied with multiple doses at 24 h intervals, and was especially effective against the chronic wound pathogen P. aeruginosa. This work highlighted that the TA-AgNPs/Alginate hydrogel is a promising material for treating complex wound biofilms.

Quaternary Phosphonium Compound Unveiled as a Potent Disinfectant against Highly Resistant Acinetobacter baumannii Clinical Isolates.

Acinetobacter baumannii is classified as a highest threat pathogen, urgently necessitating novel antimicrobials that evade resistance to combat its spread. Quaternary ammonium compounds (QACs) have afforded a valuable first line of defense against antimicrobial resistant pathogens as broad-spectrum amphiphilic disinfectant molecules. However, a paucity of innovation in this space has driven the emergence of QAC resistance. Through this work, we sought to identify next-generation disinfectant molecules with efficacy against highly resistant A. baumannii clinical isolates. We selected 12 best-in-class molecules from our previous investigations of quaternary ammonium and quaternary phosphonium compounds (QPCs) to test against a panel of 35 resistant A. baumannii clinical isolates. The results highlighted the efficacy of our next-generation compounds over leading commercial QACs, with our best-in-class QAC (2Pyr-11,11) and QPC (P6P-10,10) displaying improved activities with a few exceptions. Furthermore, we elucidated a correlation between colistin resistance and QAC resistance, wherein the only pan-resistant isolate of the panel, also harboring colistin resistance, exhibited resistance to all tested QACs. Notably, P6P-10,10 maintained efficacy against this strain with an IC90 of 3 μM. In addition, P6P-10,10 displayed minimum biofilm eradication concentrations as low as 32 μM against extensively drug resistant clinical isolates. Lastly, examining the development of disinfectant resistance and cross-resistance, we generated QAC-resistant A. baumannii mutants and observed the development of QAC cross-resistance. In contrast, neither disinfectant resistance nor cross-resistance was observed in A. baumannii under P6P-10,10 treatment. Taken together, the results of this work illustrate the need for novel disinfectant compounds to treat resistant pathogens, such as A. baumannii, and underscore the promise of QPCs, such as P6P-10,10, as viable next-generation disinfectant molecules.

Identification and characterization of bacteria isolated from patients with cystic fibrosis in Jordan

Background Notable emergence of multidrug-resistant bacteria has become increasingly problematic worldwide. Most patients with cystic fibrosis (CF) suffer from chronic persistent infections with frequent occurrence of acute exacerbations. Routine screening of bacterial strains, epidemiological characteristics, and resistance patterns are particularly useful for patient management and maintenance of infection control procedures Methods In this study, 43 pharyngeal samples were taken from patients with CF. Microbiological bacterial culture and identification, antimicrobial susceptibility testings, biofilm formation, including minimum biofilm eradication concentration (MBEC) and PCR for detecting resistance genes were performed. Results All samples were positive for bacterial growth. The predominant species were Staphylococcus aureus (41.86%; n = 18) and Pseudomonas aeruginosa (39.53%; n = 17). 30% of isolated bacteria were multidrug-resistant, resisting high concentrations of tested antibiotics. Among the 42 biofilm-forming isolates, 23.8% (n = 10) were strong biofilm formers. The occurance of resistance genes varied with blaKPC detected in 71% (n = 17) of all Gram-negative isolates and mecA found in 61% (n = 11) of all S. aureus strains. Conclusions The majority of isolated bacteria were S. aureus and P. aeruginosa. The high frequency of antimicrobial resistance, the presence of resistance genes, and biofilm formation highlight the challenge in treatment and infection control measures in patients with CF. KEY MESSAGES Staphylococcus aureus and Pseudomonas aeruginosa are the most prevalent pathogens found in patients with CF in Jordan. Detection of antimicrobial resistance genes in patients with CF confirms that antimicrobial resistance patterns must always be monitored. Biofilm formation significantly increases the tolerance of bacteria to antimicrobial agents.

Microbiological Characterization of Cutibacterium acnes Strains Isolated from Prosthetic Joint Infections.

Aims: This study aimed to characterize 79 Cutibacterium acnes strains isolated from prosthetic joint infections (PJIs) originated from eight European hospitals. Methods: Isolates were phylotyped according to the single-locus sequence typing (SLST) scheme. We evaluated the ability of the biofilm formation of C. acnes strains isolated from PJIs and 84 isolates recovered from healthy skin. Antibiotic susceptibility testing of planktonic and biofilm cells of PJI isolates and skin isolates was performed. Results: Most of the isolates from PJIs belonged to the SLST class H/phylotype IB (34.2%), followed by class D/phylotype IA1 (21.5%), class A/phylotype IA1 (18.9%), and class K/phylotype II (13.9%). All tested isolates were biofilm producers; no difference in biofilm formation was observed between the healthy skin group and the PJI group of strains. Planktonic and sessile cells of C. acnes remained highly susceptible to a broad spectrum of antibiotics, including beta-lactams, clindamycin, fluoroquinolones, linezolid, rifampin, and vancomycin. The minimal inhibitory concentrations (MICs) for planktonic and biofilm states coincided in most cases. However, the minimal biofilm eradication concentration (MBEC) was high for all antimicrobial drugs tested (>32 mg/L), except for rifampin (2 mg/L). Conclusions: C. acnes strains isolated from healthy skin were able to produce biofilm to the same extent as isolates recovered from PJIs. All C. acnes strains in planktonic and sessile states were susceptible to most antibiotics commonly used for PJI treatment, although rifampin was the only antimicrobial agent able to eradicate C. acnes embedded in biofilm.

The Efficacy of Colistin Combined with Amikacin or Levofloxacin against Pseudomonas aeruginosa Biofilm Infection.

ABSTRACTPseudomonas aeruginosa (PA) biofilm infection is clinically prevalent and difficult to eradicate. In the present work, we aimed to evaluate the in vitro and in vivo efficacy of colistin (COL)-based combinations against PA biofilm. MICs and fractional inhibitory concentration indexes (FICIs) of four antibiotics (COL, amikacin, levofloxacin, and meropenem) to bioluminescent strain PAO1, carbapenem-resistant PAO1 (CRPAO1), and clinically isolated strains were assessed. Minimal biofilm eradication concentrations (MBECs) of monotherapy and combinations were examined by counting the live bacteria in biofilm, accompanied by visual confirmation using confocal laser-scanning microscopy. An animal biofilm infection model was established by implanting biofilm subcutaneously, and the therapeutic effect was evaluated according to the change in luminescence through a live animal bio-photonic imaging system. In vitro, even combined with 4 or 8 mg/L COL, meropenem needed to reach 128 or 256 mg/L to eradicate the biofilm. Moreover, 2 mg/L COL combined with 32 mg/L amikacin or 4-8 mg/L levofloxacin could kill the PAO1 and CRPAO1 in biofilm within 24 h. In vivo, COL combined with amikacin or levofloxacin could shorten the eradication time of biofilm than monotherapy. For PAO1 biofilm, combination therapy could eradicate the biofilm in all mice on the 5th day, whereas monotherapy only eradicated biofilms in almost half of the mice. For CRPAO1 biofilm, the biofilm eradication rate on the 6th day in the COL+ amikacin, amikacin, or COL alone regimen was 90%, 10%, or 40%, respectively. COL combined with levofloxacin did not show a better effect than each individual antibiotic. COL-based combinations containing levofloxacin or amikacin were promising choices for treating PA biofilm infection.IMPORTANCE Infections associated with PA biofilm formation are extremely challenging. When monotherapy fails to achieve optimal efficacy, combination therapy becomes the last option. After evaluating multiple drug combinations through a series of experiments in vitro and in vivo, we confirmed that colistin-based combinations containing levofloxacin or amikacin were promising choices for treating PA biofilm infection. The efficacy of these combinations derives from the different bactericidal mechanisms and the bacterial susceptibility to each antibiotic. This study provided a new regimen to solve the incurable problem of biofilm by using COL combined with other antibiotics.

Investigation of the Antibiofilm Activity of Some Spices and Medicinal Plants Essential Oils

Biofilms are the structure microbial that attach to different surfaces and enclave microorganisms in a matrix composed, protecting them from harsh conditions, including immune effectors and antibiotics. Therefore, this study aimed to assess the anti-biofilm activity of lavender, cloves, eucalyptus, rosemary, thyme, and oregano commercial essential oils, known for their biocidal properties against Gram-positive and Gram-negative ESKAPE isolates, exhibiting multiple drug resistance. The most efficient proved to be the oregano, thyme, and clove essential oils, which exhibited the lowest minimal biofilm eradication concentrations values against all bacterial species. Although lavender, eucalyptus, and rosemary had a weaker effect than the first three oils, they have also inhibited biofilm development at concentrations low enough to be considered effective. This experimental approach may open new perspectives for developing efficient strategies to combat the emergent threat of antibiotic resistance and to control the formation of microbial biofilms, being also a valuable source of bioactive compounds and new anti-biofilm drugs.

Molasses-Silver Nanoparticles: Synthesis, Optimization, Characterization, and Antibiofilm Activity

Biofilms are matrix-enclosed communities of bacteria that are highly resistant to antibiotics. Adding nanomaterials with antibacterial activity to the implant surfaces may be a great solution against biofilm formation. Due to its potent and widespread antibacterial effect, silver nanoparticles were considered the most potent agent with different biological activities. In the present investigation, silver nanoparticles (AgNPs) were newly synthesized as antibiofilm agents using sugarcane process byproduct (molasses) and named Mo-capped AgNPs. The synthesized nanoparticles showed promising antimicrobial activity against S. aureus ATCC 6538 and C. albicans DAY185. Statistically designed optimization through response surface methodology was evaluated for maximum activity and better physical characteristics, namely the nanoparticles’ size and polydispersity index (PDI), and it was revealed that molasses concentration was the main effective factor. Minimal biofilm eradication concentration (MBEC) of Mo-capped AgNPs against S. aureus ATCC 6538 and C. albicans DAY185 was 16 and 32 µg/mL, respectively. Scanning electron microscope study of Mo-capped AgNP-treated biofilm revealed that AgNPs penetrated the preformed biofilm and eradicated the microbial cells. The optimally synthesized Mo-capped AgNPs were spherically shaped, and the average size diameter ranged between 29 and 88 nm with high proportions of Ag+ element (78.0%) recorded. Fourier-transform infrared spectroscopy (FTIR) analysis indicated the importance of molasses ingredients in capping and stabilizing the produced silver nanoparticles.

Antimicrobial effects of Melaleuca alternifolia (tea tree) essential oil against biofilm-forming multidrug-resistant cystic fibrosis-associated Pseudomonas aeruginosa as a single agent and in combination with commonly nebulized antibiotics.

Broth microdilution assays were used to determine minimum inhibitory concentrations (MICs) and fractional inhibitory concentration indices (FICIs) of tea tree oil (TTO), tobramycin, colistin and aztreonam (ATM) against clinical cystic fibrosis-associated Pseudomonas aeruginosa (CFPA) isolates (n = 20). The minimum biofilm eradication concentration (MBEC) and fractional biofilm eradication concentration index (FBECI) were also determined using a similar microbroth dilution checkerboard assay, with biofilms formed using the MBEC device® . TTO was effective at lower concentrations against multidrug-resistant (MDR) CFPA isolates (n = 3) in a biofilm compared to in a planktonic state (MBEC 18·7-fold lower than MIC). CFPA within biofilm was less susceptible to ATM, colistin and tobramycin compared to planktonic cells (MBEC 6·3-fold, 9·3-fold, and 2·1-fold higher than MIC respectively). All combinations of essential oil and antibiotic showed indifferent relationships (FICI 0·52-1·72) when tested against planktonic MDR CFPA isolates (n = 5). Against CFPA isolates (n = 3) in biofilm, combinations of TTO/aztreonam and TTO/colistin showed indifferent relationships (mean FBECI 0·85 and 0·60 respectively), whereas TTO/tobramycin showed a synergistic relationship (mean FBECI 0·42). The antibiofilm properties of TTO and the synergistic relationship seen between TTO and tobramycin against CFPA invitro make inhaled TTO a promising candidate as a potential therapeutic agent.

Treatment of periprosthetic joint infections guided by minimum biofilm eradication concentration (MBEC) in addition to minimum inhibitory concentration (MIC): protocol for a prospective randomised clinical trial

IntroductionProsthetic joint infections (PJIs) are disastrous complications for patients and costly for healthcare organisations. They may promote bacterial resistance due to the extensive antibiotic use necessary in the PJI treatment....

Impact of biofilm on cefotaxime killing effect against Escherichia coli

Biofilms cause chronic infections that are difficult to treat because of the resistance of microorganisms inside them. The goal is to assess the killing potential of cefotaxime against Escherichia coli in biofilms obtained from clinical isolates kept in the clinical microbiology laboratory of Dr. Soetomo Surabaya Hospital. The study was conducted by laboratory experimental design. Two steps challenged the bacterial isolates by applying cefotaxime to the planktonic bacterial state and the biofilm state. Minimum inhibitory concentration (MIC), minimum biofilm inhibitory concentration (MBIC), minimum bactericidal concentration (MBC) and minimum biofilm eradication concentration (MBEC) were used as an indicator for comparison. Nineteen isolates of E coli were used for this experiment, 7 isolates with MIC of 0.125-0.25 μg/ml (36,84%), 6 isolates with MBC value 0.25-0.5 μg/ml (31,57%). The MBIC > 128 μg/ml is 6 isolates (31,57%), MBEC > 128 μg/ml is 14 isolates (73,68%). Cefotaxime had lower killing efficacy against E. coli in biofilm than in the planktonic phase. MBIC of E. coli requires cefotaxime at minimal 5 times two-fold increase from MIC, with an average 7-8 times. MBEC of E. coli requires cefotaxime concentration minimal 5 times two-fold dilution increase from MBC, with an average 8 - 9 times.