scholarly journals Inhibitory Effects of Lipopeptides and Glycolipids on C. albicans–Staphylococcus spp. Dual-Species Biofilms

2021 ◽  
Vol 11 ◽  
Author(s):  
Chiara Ceresa ◽  
Maurizio Rinaldi ◽  
Francesco Tessarolo ◽  
Devid Maniglio ◽  
Emanuele Fedeli ◽  
...  

Microbial biofilms strongly resist host immune responses and antimicrobial treatments and are frequently responsible for chronic infections in peri-implant tissues. Biosurfactants (BSs) have recently gained prominence as a new generation of anti-adhesive and antimicrobial agents with great biocompatibility and were recently suggested for coating implantable materials in order to improve their anti-biofilm properties. In this study, the anti-biofilm activity of lipopeptide AC7BS, rhamnolipid R89BS, and sophorolipid SL18 was evaluated against clinically relevant fungal/bacterial dual-species biofilms (Candida albicans, Staphylococcus aureus, Staphylococcus epidermidis) through quantitative and qualitative in vitro tests. C. albicans–S. aureus and C. albicans–S. epidermidis cultures were able to produce a dense biofilm on the surface of the polystyrene plates and on medical-grade silicone discs. All tested BSs demonstrated an effective inhibitory activity against dual-species biofilms formation in terms of total biomass, cell metabolic activity, microstructural architecture, and cell viability, up to 72 h on both these surfaces. In co-incubation conditions, in which BSs were tested in soluble form, rhamnolipid R89BS (0.05 mg/ml) was the most effective among the tested BSs against the formation of both dual-species biofilms, reducing on average 94 and 95% of biofilm biomass and metabolic activity at 72 h of incubation, respectively. Similarly, rhamnolipid R89BS silicone surface coating proved to be the most effective in inhibiting the formation of both dual-species biofilms, with average reductions of 93 and 90%, respectively. Scanning electron microscopy observations showed areas of treated surfaces that were free of microbial cells or in which thinner and less structured biofilms were present, compared to controls. The obtained results endorse the idea that coating of implant surfaces with BSs may be a promising strategy for the prevention of C. albicans–Staphylococcus spp. colonization on medical devices, and can potentially contribute to the reduction of the high economic efforts undertaken by healthcare systems for the treatment of these complex fungal–bacterial infections.

2014 ◽  
Vol 58 (10) ◽  
pp. 5818-5830 ◽  
Author(s):  
Marc B. Habash ◽  
Amber J. Park ◽  
Emily C. Vis ◽  
Robert J. Harris ◽  
Cezar M. Khursigara

ABSTRACTPathogenic bacterial biofilms, such as those found in the lungs of patients with cystic fibrosis (CF), exhibit increased antimicrobial resistance, due in part to the inherent architecture of the biofilm community. The protection provided by the biofilm limits antimicrobial dispersion and penetration and reduces the efficacy of antibiotics that normally inhibit planktonic cell growth. Thus, alternative antimicrobial strategies are required to combat persistent infections. The antimicrobial properties of silver have been known for decades, but silver and silver-containing compounds have recently seen renewed interest as antimicrobial agents for treating bacterial infections. The goal of this study was to assess the efficacy of citrate-capped silver nanoparticles (AgNPs) of various sizes, alone and in combination with the monobactam antibiotic aztreonam, to inhibitPseudomonas aeruginosaPAO1 biofilms. Among the different sizes of AgNPs examined, 10-nm nanoparticles were most effective in inhibiting the recovery ofP. aeruginosabiofilm cultures and showed synergy of inhibition when combined with sub-MIC levels of aztreonam. Visualization of biofilms treated with combinations of 10-nm AgNPs and aztreonam indicated that the synergistic bactericidal effects are likely caused by better penetration of the small AgNPs into the biofilm matrix, which enhances the deleterious effects of aztreonam against the cell envelope ofP. aeruginosawithin the biofilms. These data suggest that small AgNPs synergistically enhance the antimicrobial effects of aztreonam againstP. aeruginosain vitro, and they reveal a potential role for combinations of small AgNPs and antibiotics in treating patients with chronic infections.


2021 ◽  
Author(s):  
Kanika Bhargava ◽  
K Gururaj ◽  
G. K. Aseri ◽  
Gopal Nath ◽  
Virendra Bahadur Yadav ◽  
...  

Abstract Due to the awareness and benefits of goat rearing in developing economies, goats' significance is increasing. Unfortunately, these ruminants are threatened via multiple bacterial pathogens such as enteropathogenic Escherichia coli (EPEC) and its pathotypes. In goat kids and lambs, EPEC causes gastrointestinal disease leading to substantial economic losses for farmers and may also pose a threat to public health via the spread of zoonotic diseases. Management of infection is primarily based on antibiotics, but the need for new therapeutic measures as an alternative to antibiotics is becoming vital because of the advent of antimicrobial resistance (AMR). The current study focuses on the prevalence of enteric diseases, their identification through various molecular techniques viz., SYBR green real-time PCR, conventional PCR based on bfpA gene, PCR based on uspA gene and isolation, purification of naturally occurring phages against three EPEC multi-drug resistant strains isolated from the neonatal goat. Bacteriophages are novel components that can be used to tackle bacterial infections and AMR, where host immune responses and antimicrobial agents become incompetent. It was observed that a PCR based approach is more effective and rapid as compared to phenotypic tests. It was also established that the isolated bacteriophages exhibited potent antibacterial efficacy in-vitro. Hence, bacteriophages, being a natural therapeutic biological agent docking bacterial host, may be explored as a potential alternative to antibiotics in managing public, livestock and environmental health in this troubling situation of AMR.


2020 ◽  
Vol 20 (3) ◽  
pp. 192-208 ◽  
Author(s):  
Talita Odriane Custodio Leite ◽  
Juliana Silva Novais ◽  
Beatriz Lima Cosenza de Carvalho ◽  
Vitor Francisco Ferreira ◽  
Leonardo Alves Miceli ◽  
...  

Background: According to the World Health Organization, antimicrobial resistance is one of the most important public health threats of the 21st century. Therefore, there is an urgent need for the development of antimicrobial agents with new mechanism of action, especially those capable of evading known resistance mechanisms. Objective: We described the synthesis, in vitro antimicrobial evaluation, and in silico analysis of a series of 1H-indole-4,7-dione derivatives. Methods: The new series of 1H-indole-4,7-diones was prepared with good yield by using a copper(II)- mediated reaction between bromoquinone and β-enamino ketones bearing alkyl or phenyl groups attached to the nitrogen atom. The antimicrobial potential of indole derivatives was assessed. Molecular docking studies were also performed using AutoDock 4.2 for Windows. Characterization of all compounds was confirmed by one- and two-dimensional NMR techniques 1H and 13C NMR spectra [1H, 13C – APT, 1H x 1H – COSY, HSQC and HMBC], IR and mass spectrometry analysis. Results: Several indolequinone compounds showed effective antimicrobial profile against Grampositive (MIC = 16 µg.mL-1) and Gram-negative bacteria (MIC = 8 µg.mL-1) similar to antimicrobials current on the market. The 3-acetyl-1-(2,5-dimethylphenyl)-1H-indole-4,7-dione derivative exhibited an important effect against different biofilm stages formed by a serious hospital life-threatening resistant strain of Methicillin-Resistant Staphylococcus aureus (MRSA). A hemocompatibility profile analysis based on in vitro hemolysis assays revealed the low toxicity effects of this new series. Indeed, in silico studies showed a good pharmacokinetics and toxicological profiles for all indolequinone derivatives, reinforcing their feasibility to display a promising oral bioavailability. An elucidation of the promising indolequinone derivatives binding mode was achieved, showing interactions with important sites to biological activity of S. aureus DNA gyrase. These results highlighted 3-acetyl-1-(2-hydroxyethyl)-1Hindole- 4,7-dione derivative as broad-spectrum antimicrobial prototype to be further explored for treating bacterial infections. Conclusion: The highly substituted indolequinones were obtained in moderate to good yields. The pharmacological study indicated that these compounds should be exploited in the search for a leading substance in a project aimed at obtaining new antimicrobials effective against Gram-negative bacteria.


Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2223
Author(s):  
Moises Bustamante-Torres ◽  
Victor H. Pino-Ramos ◽  
David Romero-Fierro ◽  
Sandra P. Hidalgo-Bonilla ◽  
Héctor Magaña ◽  
...  

The design of new polymeric systems for antimicrobial drug release focused on medical/surgical procedures is of great interest in the biomedical area due to the high prevalence of bacterial infections in patients with wounds or burns. For this reason, in this work, we present a new design of pH-sensitive hydrogels copolymerized by a graft polymerization method (gamma rays), intended for localized prophylactic release of ciprofloxacin and silver nanoparticles (AgNPs) for potential topical bacterial infections. The synthesized hydrogels were copolymerized from acrylic acid (AAc) and agar. Cross-linked hydrogel film formation depended on monomer concentrations and the degree of radiation used (Cobalt-60). The obtained hydrogel films were characterized by attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and mechanical testing. The swelling of the hydrogels was evidenced by the influence of their pH-sensitiveness. The hydrogel was loaded with antimicrobial agents (AgNPs or ciprofloxacin), and their related activity was evaluated. Finally, the antimicrobial activity of biocidal-loaded hydrogel was tested against Escherichia coli (E. coli) and methicillin-resistant Staphylococcus aureus (MRSA) on in vitro conditions.


2021 ◽  
Author(s):  
Zhexian Liu ◽  
Sarzana S. Hossain ◽  
Zayda Morales Moreira ◽  
Cara H. Haney

Pseudomonas aeruginosa , an opportunistic bacterial pathogen can synthesize and catabolize a number of small cationic molecules known as polyamines. In several clades of bacteria polyamines regulate biofilm formation, a lifestyle-switching process that confers resistance to environmental stress. The polyamine putrescine and its biosynthetic precursors, L-arginine and agmatine, promote biofilm formation in Pseudomonas spp. However, it remains unclear whether the effect is a direct effect of polyamines or through a metabolic derivative. Here we used a genetic approach to demonstrate that putrescine accumulation, either through disruption of the spermidine biosynthesis pathway or the catabolic putrescine aminotransferase pathway, promoted biofilm formation in P. aeruginosa . Consistent with this observation, exogenous putrescine robustly induced biofilm formation in P. aeruginosa that was dependent on putrescine uptake and biosynthesis pathways. Additionally, we show that L-arginine, the biosynthetic precursor of putrescine, also promoted biofilm formation, but via a mechanism independent of putrescine or agmatine conversion. We found that both putrescine and L-arginine induced a significant increase in the intracellular level of bis-(3′-5′)-cyclic dimeric guanosine monophosphate (c-di-GMP) (c-di-GMP), a bacterial second messenger widely found in Proteobacteria that upregulates biofilm formation. Collectively these data show that putrescine and its metabolic precursor arginine promote biofilm and c-di-GMP synthesis in P. aeruginosa . Importance: Biofilm formation allows bacteria to physically attach to a surface, confers tolerance to antimicrobial agents, and promotes resistance to host immune responses. As a result, regulation of biofilm is often crucial for bacterial pathogens to establish chronic infections. A primary mechanism of biofilm promotion in bacteria is the molecule c-di-GMP, which promotes biofilm formation. The level of c-di-GMP is tightly regulated by bacterial enzymes. In this study, we found that putrescine, a small molecule ubiquitously found in eukaryotic cells, robustly enhances P. aeruginosa biofilm and c-di-GMP. We propose that P. aeruginosa may sense putrescine as a host-associated signal that triggers a lifestyle switching that favors chronic infection.


Author(s):  
Na Li ◽  
Yigang Zeng ◽  
Rong Bao ◽  
Tongyu Zhu ◽  
Demeng Tan ◽  
...  

Klebsiella pneumoniae is a dominant cause of community-acquired and nosocomial infections, specifically among immunocompromised individuals. The increasing occurrence of multidrug-resistant (MDR) isolates has significantly impacted the effectiveness of antimicrobial agents. As antibiotic resistance is becoming increasingly prevalent worldwide, the use of bacteriophages to treat pathogenic bacterial infections has recently gained attention. Elucidating the details of phage-bacteria interactions will provide insights into phage biology and the better development of phage therapy. In this study, a total of 22 K. pneumoniae isolates were assessed for their genetic and phenotypic relatedness by multi-locus sequence typing (MLST), endonuclease S1 nuclease pulsed-field gel electrophoresis (S1-PFGE), and in vitro antibiotic susceptibility testing. In addition, the beta-lactamase gene (blaKPC) was characterized to determine the spread and outbreak of K. pneumoniae carbapenemase (KPC)-producing enterobacterial pathogens. Using these ST11 carbapenem-resistant K. pneumoniae isolates, three phages (NL_ZS_1, NL_ZS_2, and NL_ZS_3) from the family of Podoviridae were isolated and characterized to evaluate the application of lytic phages against the MDR K. pneumoniae isolates. In vitro inhibition assays with three phages and K. pneumoniae strain ZS15 demonstrated the strong lytic potential of the phages, however, followed by the rapid growth of phage-resistant and phage-sensitive mutants, suggesting several anti-phage mechanisms had developed in the host populations. Together, this data adds more comprehensive knowledge to known phage biology and further emphasizes their complexity and future challenges to overcome prior to using phages for controlling this important MDR bacterium.


2017 ◽  
Vol 61 (11) ◽  
Author(s):  
Marc B. Habash ◽  
Mara C. Goodyear ◽  
Amber J. Park ◽  
Matthew D. Surette ◽  
Emily C. Vis ◽  
...  

ABSTRACT Increasing antibiotic resistance among pathogenic bacterial species is a serious public health problem and has prompted research examining the antibacterial effects of alternative compounds and novel treatment strategies. Compounding this problem is the ability of many pathogenic bacteria to form biofilms during chronic infections. Importantly, these communities are often recalcitrant to antibiotic treatments that show effectiveness against acute infection. The antimicrobial properties of silver have been known for decades, but recently silver and silver-containing compounds have seen renewed interest as antimicrobial agents for treating bacterial infections. The goal of this study was to assess the ability of citrate-capped silver nanoparticles (AgNPs) of various sizes, alone and in combination with the aminoglycoside antibiotic tobramycin, to inhibit established Pseudomonas aeruginosa biofilms. Our results demonstrate that smaller 10-nm and 20-nm AgNPs were more effective at synergistically potentiating the activity of tobramycin. Visualization of biofilms treated with combinations of 10-nm AgNPs and tobramycin reveals that the synergistic bactericidal effect may be caused by disrupting cellular membranes. Minimum biofilm eradication concentration (MBEC) assays using clinical P. aeruginosa isolates shows that small AgNPs are more effective than larger AgNPs at inhibiting biofilms, but that the synergy effect is likely a strain-dependent phenomenon. These data suggest that small AgNPs synergistically potentiate the activity of tobramycin against P. aeruginosa in vitro and may reveal a potential role for AgNP/antibiotic combinations in treating patients with chronic infections in a strain-specific manner.


2017 ◽  
Vol 14 (2) ◽  
pp. 161-166 ◽  
Author(s):  
M. T. Hasan ◽  
M. R. Islam ◽  
N. S. Runa ◽  
M, N. Hasan ◽  
A. H. M. M. Uddin ◽  
...  

The study was conducted to find out the prevalence of sub-clinical mastitis (SCM) and antibiogram of the causative bacteria in dairy cows at the Sylhet govt. Dairy Farm (SGDF) and Local Farms of Sylhet (LFS) during the period of July2014 to June2015. These farms were selected to assess the predominant types of bacteria involved in causing sub-clinical mastitis and to know the in vitro antibiotic sensitivity spectrum of these bacterial isolates against the commonly used antibiotics and to study the economic effects due to SCM. Use of California Mastitis Test (CMT) for the detection of sub-clinical mastitis showed 42out of 100 samples were test positive, among which +(Trace) 22.0%, ++(Distinct) 12.0%, +++(Strong) 3.0%, ±(Doubtful) 5.0%.  Bacteriological examination of milk samples of 100 milch cows (400 quarters) revealed that 42 cows (42.0%) had suffering from SCM with different bacterial infection with 95% confidence limit was 32.1574-51.8426. Among 42 positive samples31 (31.0%) cows had mono-bacterial infection and 11 (11.0%) cows had mixed bacterial infections. Statistical analysis of the result of single and mixed bacterial infections in the milk of apparently healthy milch cows revealed that the single infection was significantly (P < 0.05) higher than mixed bacterial infection. Of the 31 mono-bacterial isolates, of which 23 (23.0%) isolates were Staphylococci, 3 (3.0%) isolates were Escherichia coli, 5 (5.0%) isolated Streptococcus spp. The 11 cows had mixed infection, of which 5 had Staphylococcus spp. + Streptococcus spp., 3 had E. coli + Staphylococcus spp., and 3 had Streptococcus spp. + E. coli. Of 42 positive cases of SCM Staphylococcus spp. isolated from 23 samples. Among these 23 positive samples 13 obtained from SGDF (37.14%) and 10 obtained from LFS (15.38%). Escherichia coli isolated from 3 samples. Among these 3 positive samples 3 obtained from LFS (4.62%). Streptococcus spp. isolated from 5 samples. Among these 5 positive samples 1 obtained from SGDF (2.86%) and 4 obtained from LFS (6.15%). Ceftriaxone, ciprofloxacin and gentamicin were the best drug for treating sub-clinical mastitis.


2019 ◽  
Vol 26 (14) ◽  
pp. 2529-2535 ◽  
Author(s):  
Anand Srinivasan ◽  
Anand K. Ramasubramanian ◽  
José L. Lopez-Ribot

Biofilms are the predominant mode of microbial growth and it is now fully accepted that a majority of infections in humans are associated with a biofilm etiology. Biofilms are defined as attached and structured microbial communities surrounded by a protective exopolymeric matrix. Importantly, sessile microorganisms growing within a biofilm are highly resistant to antimicrobial agents. Thus, there is an urgent need to develop new and improved anti-biofilm therapies. Unfortunately, most of the current techniques for in-vitro biofilm formation are not compatible with high throughput screening techniques that can speed up discovery of new drugs with anti-biofilm activity. To try to overcome this major impediment, our group has developed a novel technique consisting of micro-scale culture of microbial biofilms on a microarray platform. Using this technique, hundreds to thousands of microbial biofilms, each with a volume of approximately 30-50 nanolitres, can be simultaneously formed on a standard microscope slide. Despite more than three orders of magnitude of miniaturization over conventional biofilms, these nanobiofilms display similar growth, structural and phenotypic properties, including antibiotic drug resistance. These nanobiofilm chips are amenable to automation, drastically reducing assay volume and costs. This technique platform allows for true high-throughput screening in search for new anti-biofilm drugs.


2021 ◽  
Author(s):  
Bryan Garcia ◽  
Melissa S. McDaniel ◽  
Allister J. Loughran ◽  
J. Dixon Johns ◽  
Vidya Narayanaswamy ◽  
...  

Pseudomonas aeruginosa is a common opportunistic pathogen that can cause chronic infections in multiple disease states, including respiratory infections in patients with cystic fibrosis (CF) and non-CF bronchiectasis. Like many opportunists, P. aeruginosa forms multicellular biofilm communities that are widely thought to be an important determinant of bacterial persistence and resistance to antimicrobials and host immune effectors during chronic/recurrent infections. Poly (acetyl, arginyl) glucosamine (PAAG) is a glycopolymer which has antimicrobial activity against a broad range of bacterial species, and also has mucolytic activity which can normalize rheologic properties of cystic fibrosis mucus. In this study, we sought to evaluate the effect of PAAG on P. aeruginosa bacteria within biofilms in vitro, and in the context of experimental pulmonary infection in a rodent infection model. PAAG treatment caused significant bactericidal activity against P. aeruginosa biofilms, and a reduction in the total biomass of preformed P. aeruginosa biofilms on abiotic surfaces, as well as on the surface of immortalized cystic fibrosis human bronchial epithelial cells. Studies of membrane integrity indicated that PAAG causes changes to P. aeruginosa cell morphology and dysregulates membrane polarity. PAAG treatment reduced infection and consequent tissue inflammation in experimental P. aeruginosa rat infections. Based on these findings we conclude that PAAG represents a novel means to combat P. aeruginosa infection, which may warrant further evaluation as a therapeutic.


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