TB acknowledges a research fellowship from Cystic Fibrosis Canada.

Note that Research Ethics Board (REB) is required to collect and store sputum samples from human subjects. These studies were approved by the Hospital for Sick Children REB#1000019444.
1. Preparing CF Sputum Samples
<ol>
	<li>Collect sputum sample from patients during routine visits to the cystic fibrosis clinic and keep on ice.</li>
	<li>Transport sputum sample on ice within the first hour of collection, to the research laboratory, to undergo processing.</li>
</ol>
2. Sputum Processing
<ol>
	<li>Record the volume of the sputum sample obtained. Add phosphate buffered saline (PBS) to 2x the volume of the sample (i.e., 2 parts PBS, 1 part sample).</li>
	<li>Mix the sample well with a transfer pipette. Vortex the sample on the highest setting for 1 min to mix completely.</li>
	<li>Aliquot 1 ml of the above mixture into the appropriate number 1.5 ml microcentrifuge tubes and spin down at 5,000 x g for 20 min at 4 &#176;C.</li>
	<li>Following centrifugation, remove the supernatant and discard the pellet.</li>
	<li>Filter sterilize the supernatant through a 0.22 &#181;m filter and collect in a clean microcentrifuge tube. 
	NOTE: Sterility of filtrate is tested by plating on LB agar and inoculating liquid media.</li>
	<li>Store sputum supernatant at -80 &#176;C for future use. 
	NOTE: Sputum from multiple patients can also be pooled following filtration.</li>
	<li>Prior to use, dilute sputum filtrate 1/10 v/v (100 &#956;l of sputum, 900 &#956;l of media) in desired media. 
	NOTE: Here, standard lysogeny broth (LB) media was used.</li>
</ol>
3. Chambered Coverglass Method for Biofilm Formation
<ol>
	<li>Grow bacterial isolate of interest overnight in desired media at 37 &#176;C with shaking (200 rpm). 
	Note: A number of different bacteria were used, including clinical isolates Pseudomonas aeruginosa, Staphylococcus aureus, Burkholderia cepacia complex and Achromobacter xylosoxidans. Choice of media depends on strains and conditions of interest, however LB media can be used for initial experiments.</li>
	<li>From overnight culture, place 40 &#956;l of culture into 4 ml of fresh media and grow for 3-4 hr at 37 &#176;C with shaking (200 RPM) to obtain a culture with an optical density at 600 nm (OD600) of approximately 0.5-0.6.</li>
	<li>Dilute the culture from step 3.2 to 1/5 in desired media with 10% sputum filtrate or without sputum filtrate (as control). Other concentration of sputum filtrate can be tested (i.e., 50% or 100%).</li>
	<li>Use 200 &#956;l of the dilution to seed wells of slide chambers.</li>
	<li>Allow bacteria to attach for 4 hr at 37 &#176;C without shaking.</li>
	<li>After 4 hr, remove the media and gently wash the biofilm with 1x fresh media. Replace with 200 &#956;l fresh media. 
	NOTE: To study the effects of sputum on the biofilm, the fresh media should contain sputum supernatant.</li>
	<li>Allow biofilms to grow for desired amount of time at 37 &#176;C without shaking, replacing media every 12 hr, without washing until the time for microscopy. 
	NOTE: To study the effect of sputum supernatants on biofilm antibiotic susceptibility, antibiotics are added to the media following 24 hr of biofilm growth and are maintained in the media until staining and imaging of biofilms.</li>
</ol>
4. Staining Biofilms and Confocal Microscopy
<ol>
	<li>Following desired growth time (24-48 hr works best), remove media from chamber wells and gently wash each chamber twice with 300 &#956;l of sterile PBS.</li>
	<li>Prepare staining mixture for biofilm by mixing 1 &#181;l of each dye (provided in the viability kit) for each ml of solution needed. Make dye in water or media solution. 
	NOTE: Water is recommended by the manufacturer.</li>
	<li>Add 200 &#181;l of dye mixture to each well of chambered coverglass and incubate at room temperature, in the dark for 45 min.</li>
	<li>Remove staining mixture from chambers and wash each well with 300 &#956;l of sterile PBS. Remove PBS and replace with fresh water or media.</li>
	<li>Proceed with visualization of biofilms via confocal microscopy.</li>
</ol>
5. Visualizing Biofilms with Confocal Microscopy
<ol>
	<li>Read stained biofilms in chambers immediately after staining (within 1 hr). Minimize delay in visualization of the slides by staining 1 to 2 8-well chambers at a time.</li>
	<li>Perform imaging using confocal microscope with lasers for excitation and filter sets for acquisition. 
	NOTE: Here, the spinning disk confocal system with spectral borealis lasers (Green: 491nm, Red: 561 nm) were used for excitation. Emission filter sets of 515/40 and 624/40 were used to visualize the stains from the biofilm viability kit.</li>
	<li>Take images using a 25X water objective on confocal microscope with camera.</li>
	<li>Use Z-Stacks to model the biofilm. Take images every 0.5-1 &#956;m starting from the first in-focus plane to the last in-focus frame of the biofilm (typically spanning 30-80 &#956;m for 48 hr biofilms)</li>
	<li>Take 3-5 images from each well. 
	NOTE: Thus for an 8 well chambered coverglass, 24-40 images will be generated.</li>
	<li>Save images for analysis. 
	NOTE: Images should be saved as OME-TIFF files to be analyzed using COMSTAT18,19. Instructions for biofilm image analysis can be found at http://www.comstat.dk/. Once images are imported, parameters such as average thickness, biomass and surface coverage for each channel (red and green) can be analyzed.</li>
</ol>

<ol>
	<li>Beaudoin, T., Waters, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Infections+with+biofilm+formation:+selection+of+antimicrobials+and+role+of+prolonged+antibiotic+therapy.">Infections with biofilm formation: selection of antimicrobials and role of prolonged antibiotic therapy.</a> Pediatr.Infect.Dis.J. , (2016).</li><li>Donlan, R. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biofilms:+microbial+life+on+surfaces.">Biofilms: microbial life on surfaces.</a> Emerg.Infect.Dis. 8 (9), 881-890 (2002).</li><li>Hobley, L., Harkins, C., MacPhee, C. E., Stanley-Wall, N. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Giving+structure+to+the+biofilm+matrix:+an+overview+of+individual+strategies+and+emerging+common+themes.">Giving structure to the biofilm matrix: an overview of individual strategies and emerging common themes.</a> FEMS Microbiol.Rev. 39 (5), 649-669 (2015).</li><li>Katharios-Lanwermeyer, S., Xi, C., Jakubovics, N. S., Rickard, A. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mini-review:+Microbial+coaggregation:+ubiquity+and+implications+for+biofilm+development.">Mini-review: Microbial coaggregation: ubiquity and implications for biofilm development.</a> Biofouling. 30 (10), 1235-1251 (2014).</li><li>Donlan, R. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biofilm+formation:+a+clinically+relevant+microbiological+process.">Biofilm formation: a clinically relevant microbiological process.</a> Clin.Infect.Dis. 33 (8), 1387-1392 (2001).</li><li>Bjarnsholt, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+in+vivo+biofilm.">The in vivo biofilm.</a> Trends Microbiol. 21 (9), 466-474 (2013).</li><li>Mah, T. F., Pitts, B., Pellock, B., Walker, G. C., Stewart, P. S., O'Toole, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+genetic+basis+for+Pseudomonas+aeruginosa+biofilm+antibiotic+resistance.">A genetic basis for Pseudomonas aeruginosa biofilm antibiotic resistance.</a> Nature. 426 (6964), 306-310 (2003).</li><li>Mah, T. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biofilm-specific+antibiotic+resistance.">Biofilm-specific antibiotic resistance.</a> Future Microbiol. 7 (9), 1061-1072 (2012).</li><li>Beaudoin, T., Zhang, L., Hinz, A. J., Parr, C. J., Mah, T. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+biofilm-specific+antibiotic+resistance+gene+ndvB+is+important+for+expression+of+ethanol+oxidation+genes+in+Pseudomonas+aeruginosa+biofilms.">The biofilm-specific antibiotic resistance gene ndvB is important for expression of ethanol oxidation genes in Pseudomonas aeruginosa biofilms.</a> J. Bacteriol. 194 (12), 3128-3136 (2012).</li><li>Beaudoin, T., Aaron, S. D., Giesbrecht-Lewis, T., Vandemheen, K., Mah, T. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+clonal+strains+of+Pseudomonas+aeruginosa+isolated+from+cystic+fibrosis+patients+in+Ontario,+Canada.">Characterization of clonal strains of Pseudomonas aeruginosa isolated from cystic fibrosis patients in Ontario, Canada.</a> Can. J. Microbiol. 56 (7), 548-557 (2010).</li><li>Vidya, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chronic+infection+phenotypes+of+Pseudomonas+aeruginosa+are+associated+with+failure+of+eradication+in+children+with+cystic+fibrosis.">Chronic infection phenotypes of Pseudomonas aeruginosa are associated with failure of eradication in children with cystic fibrosis.</a> Eur.J.Clin.Microbiol.Infect.Dis. , (2015).</li><li>Beaudoin, T., Lafayette, S., Nguyen, D., Rousseau, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mucoid+Pseudomonas+aeruginosa+caused+by+mucA+mutations+result+in+activation+of+TLR2+in+addition+to+TLR5+in+airway+epithelial+cells.">Mucoid Pseudomonas aeruginosa caused by mucA mutations result in activation of TLR2 in addition to TLR5 in airway epithelial cells.</a> Biochem.Biophys.Res.Commun. 428 (1), 150-154 (2012).</li><li>Beaudoin, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+level+of+p38alpha+mitogen-activated+protein+kinase+activation+in+airway+epithelial+cells+determines+the+onset+of+innate+immune+responses+to+planktonic+and+biofilm+Pseudomonas+aeruginosa.">The level of p38alpha mitogen-activated protein kinase activation in airway epithelial cells determines the onset of innate immune responses to planktonic and biofilm Pseudomonas aeruginosa.</a> J.Infect.Dis. 207 (10), 1544-1555 (2013).</li><li>LaFayette, S. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cystic+fibrosis-adapted+quorum+sensing+mutants+cause+hyperinflammatory+responses.">Cystic fibrosis-adapted quorum sensing mutants cause hyperinflammatory responses.</a> Sci.Adv. 1 (6), e1500199 (2015).</li><li>Staudinger, B. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conditions+associated+with+the+cystic+fibrosis+defect+promote+chronic+Pseudomonas+aeruginosa+infection.">Conditions associated with the cystic fibrosis defect promote chronic Pseudomonas aeruginosa infection.</a> Am.J.Respir.Crit.Care Med. 189 (7), 812-824 (2014).</li><li>Kennedy, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Activity+of+Tobramycin+against+Cystic+Fibrosis+Isolates+of+Burkholderia+cepacia+Complex+Grown+as+Biofilms.">Activity of Tobramycin against Cystic Fibrosis Isolates of Burkholderia cepacia Complex Grown as Biofilms.</a> Antimicrob.Agents Chemother. 60 (1), 348-355 (2015).</li><li>Tom, S. K., Yau, Y. C., Beaudoin, T., LiPuma, J. J., Waters, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+High-Dose+Antimicrobials+on+Biofilm+Growth+of+Achromobacter+Species+Isolated+from+Cystic+Fibrosis+Patients.">Effect of High-Dose Antimicrobials on Biofilm Growth of Achromobacter Species Isolated from Cystic Fibrosis Patients.</a> Antimicrob.Agents Chemother. 60 (1), 650-652 (2015).</li><li>Heydorn, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantification+of+biofilm+structures+by+the+novel+computer+program+COMSTAT.">Quantification of biofilm structures by the novel computer program COMSTAT.</a> Microbiology. 146 (Pt 10), 2395-2407 (2000).</li><li>Vorregaard, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Informatics and Mathematical Modelling. , (2008).</li><li>Jurcisek, J. A., Dickson, A. C., Bruggeman, M. E., Bakaletz, L. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vitro+Biofilm+Formation+in+an+8-well+Chamber+Slide.">In vitro Biofilm Formation in an 8-well Chamber Slide.</a> J. Vis. Exp. (47), e2481 (2011).</li></ol>

The methods described herein allow for visualization of bacterial biofilms grown in the presence of exogenous products. Not surprisingly, the production of the exoproducts is of importance when using this type of system. For instance, Dithiothreitol (DTT), is often used on human sputum samples to help liquefy the samples. However, the effect of DTT alone can decrease biofilm development and viability (data not shown). Thus, proper controls for all conditions are necessary. Furthermore, the addition of human sputum produc...

Bacterial biofilms are groups of microorganisms that are attached to one another and encased in a self-secreted matrix.1,2 Classically, they represent bacteria physically attached to an abiotic or biotic surface formed under conditions of flow. Biofilms have also been shown to grow in static conditions (absence of flow) and distal from surfaces, such as at the air-liquid interface of thermal pools or pellicles formed in test tubes. These biofilms have long been recognized in the environment and are a major detriment to industrial processes, as they can form in water reservoirs or in pipes, resulting in biofouling, corrosion and blockages.3,4
Biofilms are also critical in healthcare settings, as they have been shown be involved in catheter related infections, pulmonary infections in cystic fibrosis patients, as well as in numerous other infections.5,6 One of the hallmarks of biofilm infections is the decreased susceptibility of bacteria to antibiotics and impaired clearance by the innate immune system.7-9 The most well studied, clinically relevant scenarios involving biofilm-based infection occurs in patients with cystic fibrosis (CF), who are chronically infected with Pseudomonas aeruginosa biofilms. P. aeruginosa can undergo a number of changes during establishment of chronic infection that make it very difficult to treat.10,11 Biofilms can differentially activate innate immunity and drive inflammation.12-14 As these infections lead to increased morbidity and mortality in CF patients, it is crucial to understand factors that can affect biofilm development in this context.
A recent study suggests that host-factors are critical in the formation of P. aeruginosa biofilm aggregates.15 These biofilms contribute to reduced susceptibility to antibiotics and host defense mechanisms. The presence of host-derived factors, such as neutrophil elastase, as well as secreted products from microorganisms present in the CF lung, have the potential to greatly modulate biofilm formation and development.16 Additionally, biofilms interact with the host to modulate expression of numerous pathways and initiate inflammation. While high throughput methods, such as the standard crystal violet assay, can provide some information with regards to the biofilm process, visualization of the biofilm in response to these factors provide more in-depth information.
In this manuscript we describe a method for using factors from the sputum of patients with CF to study the development of biofilms in vitro. This method allows for rapid visualization of biofilms exposed to sputum containing host factors using a commercial biofilm viability kit. This technique can be used to visually identify changes that occur during biofilm growth in the presence of exogenous products, and represents an improved method to analyze the changes in biofilm development under various conditions.

<table><tbody><tr><td>Lab-Tek II Chambered coverglass, #1.5 borosilicate, 8-well</td><td>Thermo Sicher Scientific</td><td>155409</td><td></td></tr><tr><td>Filmtracer Live/Dead Biofilm Viabilty Kit</td><td>Thermo Fisher Scientific</td><td>L10316</td><td></td></tr><tr><td>Blood agar plates</td><td>Thermo Fisher Scientific</td><td>R10215</td><td>Confirming viability via CFU counts or selecting colonies for innoculation</td></tr><tr><td>COMSTAT</td><td>Availble software online</td><td></td><td>COMSTAT is software to analyze biofilm images. Available www.comstat.dk&amp;nbsp;</td></tr><tr><td>Millers LB Broth</td><td>Thermo Fisher Scientific</td><td>12780-052</td><td>Standard media for overnight gowth/biofilm growth</td></tr><tr><td>Millex-GV Syringe Filters</td><td>Millipore</td><td>SLGV013SL</td><td>Filtering of sputum supernants</td></tr><tr><td>Phosphate Buffered Saline (Dulbecco A)</td><td>Oxoid</td><td>BR0014G</td><td>Washing of biofilm chambers after media removal</td></tr><tr><td>Zeiss AxioVert 200M</td><td>Carl Zeiss</td><td></td><td></td></tr><tr><td>Hamamatsu C9100-13 EM-CCD</td><td>QS Technologies Inc.</td><td></td><td></td></tr><tr><td>Spectral Borealis</td><td>Qs Technologies Inc.</td><td></td><td></td></tr><tr><td>Perkin Elmer Volocity</td><td>QS Technologies Inc.</td><td></td><td>Instructions for this software can be found at: http://cellularimaging.perkinelmer.com/pdfs/manuals/VolocityuserGuide.pdf</td></tr></tbody></table>

visualizing the effects of sputum on biofilm development using a chambered coverglass model

Biofilms consist of groups of bacteria encased in a self-secreted matrix. They play an important role in industrial contamination as well as in the development and persistence of many health related infections. One of the most well described and studied biofilms in human disease occurs in chronic pulmonary infection of cystic fibrosis patients. When studying biofilms in the context of the host, many factors can impact biofilm formation and development. In order to identify how host factors may affect biofilm formation and development, we used a static chambered coverglass method to grow biofilms in the presence of host-derived factors in the form of sputum supernatants. Bacteria are seeded into chambers and exposed to sputum filtrates. Following 48 hr of growth, biofilms are stained with a commercial biofilm viability kit prior to confocal microscopy and analysis. Following image acquisition, biofilm properties can be assessed using different software platforms. This method allows us to visualize key properties of biofilm growth in presence of different substances including antibiotics.

The overall design of the experiment is represented in Figure 1. The use of this protocol provides a convenient method to visualize the changes in biofilms grown for different periods of time (e.g., 24, 48 or 72 hr). Importantly, exogenous signals, such as sputum filtrates, can be added to visualize the changes in biofilm development. As seen in Figure 2, the presence of 10% sputum filtrates can change the architecture of the biofilm (Fig...

Watch this Scientific Journal Video about Visualizing the Effects of Sputum on Biofilm Development Using a Chambered Coverglass Model at JoVE.com

Visualizing the Effects of Sputum on Biofilm Development Using a Chambered Coverglass Model

This protocol describes the visualization of biofilm development following exposure to host-factors using a slide chamber model. This model allows for direct visualization of biofilm development as well as analysis of biofilm parameters using computer software programs.

Biofilms consist of groups of bacteria encased in a self-secreted matrix. They play an important role in industrial contamination as well as in the ...

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Universidad de Cartagena UDEC

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Immunology and Infection

8.3K Views.  Hospital for Sick Children. This protocol describes the visualization of biofilm development following exposure to host-factors using a slide chamber model. This model allows for direct visualization of biofilm development as well as analysis of biofilm parameters using computer software programs.

Video: Visualizing the Effects of Sputum on Biofilm Development Using a Chambered Coverglass Model

Co-culture Models of Pseudomonas aeruginosa Biofilms Grown on Live Human Airway Cells

Bacterial biofilms have been associated with a number of different human diseases, but biofilm development has generally been studied on non-living surfaces. In this paper, we describe protocols for forming Pseudomonas aeruginosa biofilms on human airway epithelial cells (CFBE cells) grown in culture. In the first method (termed the Static Co-culture Biofilm Model), P. aeruginosa is incubated with CFBE cells grown as confluent monolayers on standard tissue culture plates. Although the bacterium is quite toxic to epithelial cells, the addition of arginine delays the destruction of the monolayer long enough for biofilms to form on the CFBE cells. The second method (termed the Flow Cell Co-culture Biofilm Model), involves adaptation of a biofilm flow cell apparatus, which is often used in biofilm research, to accommodate a glass coverslip supporting a confluent monolayer of CFBE cells. This monolayer is inoculated with P. aeruginosa and a peristaltic pump then flows fresh medium across the cells. In both systems, bacterial biofilms form within 6-8 hours after inoculation. Visualization of the biofilm is enhanced by the use of P. aeruginosa strains constitutively expressing green fluorescent protein (GFP). The Static and Flow Cell Co-culture Biofilm assays are model systems for early P. aeruginosa infection of the Cystic Fibrosis (CF) lung, and these techniques allow different aspects of P. aeruginosa biofilm formation and virulence to be studied, including biofilm cytotoxicity, measurement of biofilm CFU, and staining and visualizing the biofilm.

Co-culture Models of Pseudomonas aeruginosa Biofilms Grown on Live Human Airway Cells

This paper describes different methods of growing Pseudomonas aeruginosa biofilms on cultured human airway epithelial cells. These protocols can be adapted to study different aspects of biofilm formation, including visualization of the biofilm, staining of the biofilm, measuring the colony forming units (CFU) of the biofilm, and studying biofilm cytotoxicity.

Bacterial biofilms have been associated with a number of different human diseases, but biofilm development has generally been studied on non-living ...

In vitro Biofilm Formation in an 8-well Chamber Slide

The chronic nature of many diseases is attributed to the formation of bacterial biofilms which are recalcitrant to traditional antibiotic therapy. Biofilms are community-associated bacteria attached to a surface and encased in a matrix. The role of the extracellular matrix is multifaceted, including facilitating nutrient acquisition, and offers significant protection against environmental stresses (e.g. host immune responses). In an effort to acquire a better understanding as to how the bacteria within a biofilm respond to environmental stresses we have used a protocol wherein we visualize bacterial biofilms which have formed in an 8-well chamber slide. The biofilms were stained with the BacLight Live/Dead stain and examined using a confocal microscope to characterize the relative biofilm size, and structure under varying incubation conditions. Z-stack images were collected via confocal microscopy and analyzed by COMSTAT. This protocol can be used to help elucidate the mechanism and kinetics by which biofilms form, as well as identify components that are important to biofilm structure and stability.

In vitro Biofilm Formation in an 8-well Chamber Slide

This article describes the procedure for the formation and visualization of a bacterial biofilm grown within an 8-well chamber slide

The chronic nature of many diseases is attributed to the formation of bacterial biofilms which are recalcitrant to traditional antibiotic therapy. ...

Growth of Mycobacterium tuberculosis Biofilms

Mycobacterium tuberculosis, the etiologic agent of human tuberculosis, has an extraordinary ability to survive against environmental stresses including antibiotics. Although stress tolerance of M. tuberculosis is one of the likely contributors to the 6-month long chemotherapy of tuberculosis 1, the molecular mechanisms underlying this characteristic phenotype of the pathogen remain unclear. Many microbial species have evolved to survive in stressful environments by self-assembling in highly organized, surface attached, and matrix encapsulated structures called biofilms 2-4. Growth in communities appears to be a preferred survival strategy of microbes, and is achieved through genetic components that regulate surface attachment, intercellular communications, and synthesis of extracellular polymeric substances (EPS) 5,6. The tolerance to environmental stress is likely facilitated by EPS, and perhaps by the physiological adaptation of individual bacilli to heterogeneous microenvironments within the complex architecture of biofilms 7.
In a series of recent papers we established that M. tuberculosis and Mycobacterium smegmatis have a strong propensity to grow in organized multicellular structures, called biofilms, which can tolerate more than 50 times the minimal inhibitory concentrations of the anti-tuberculosis drugs isoniazid and rifampicin 8-10. M. tuberculosis, however, intriguingly requires specific conditions to form mature biofilms, in particular 9:1 ratio of headspace: media as well as limited exchange of air with the atmosphere 9. Requirements of specialized environmental conditions could possibly be linked to the fact that M. tuberculosis is an obligate human pathogen and thus has adapted to tissue environments. In this publication we demonstrate methods for culturing M. tuberculosis biofilms in a bottle and a 12-well plate format, which is convenient for bacteriological as well as genetic studies. We have described the protocol for an attenuated strain of M. tuberculosis, mc27000, with deletion in the two loci, panCD and RD1, that are critical for in vivo growth of the pathogen 9. This strain can be safely used in a BSL-2 containment for understanding the basic biology of the tuberculosis pathogen thus avoiding the requirement of an expensive BSL-3 facility. The method can be extended, with appropriate modification in media, to grow biofilm of other culturable mycobacterial species.
Overall, a uniform protocol of culturing mycobacterial biofilms will help the investigators interested in studying the basic resilient characteristics of mycobacteria. In addition, a clear and concise method of growing mycobacterial biofilms will also help the clinical and pharmaceutical investigators to test the efficacy of a potential drug.

Growth of Mycobacterium tuberculosis Biofilms

Mycobacterium tuberculosis forms drug tolerant biofilms when cultured in certain conditions. Here we describe methods for culturing M. tuberculosis biofilms and determining the frequency of drug tolerant persisters. These protocols will be useful for further studies into the mechanisms of drug tolerance in M. tuberculosis.

Mycobacterium tuberculosis, the etiologic agent of human tuberculosis, has an extraordinary ability to survive against environmental stresses including ...

Use of Artificial Sputum Medium to Test Antibiotic Efficacy Against Pseudomonas aeruginosa in Conditions More Relevant to the Cystic Fibrosis Lung

There is growing concern about the relevance of in vitro antimicrobial susceptibility tests when applied to isolates of P. aeruginosa from cystic fibrosis (CF) patients. Existing methods rely on single or a few isolates grown aerobically and planktonically. Predetermined cut-offs are used to define whether the bacteria are sensitive or resistant to any given antibiotic1. However, during chronic lung infections in CF, P. aeruginosa populations exist in biofilms and there is evidence that the environment is largely microaerophilic2. The stark difference in conditions between bacteria in the lung and those during diagnostic testing has called into question the reliability and even relevance of these tests3.
 Artificial sputum medium (ASM) is a culture medium containing the components of CF patient sputum, including amino acids, mucin and free DNA. P. aeruginosa growth in ASM mimics growth during CF infections, with the formation of self-aggregating biofilm structures and population divergence4,5,6. The aim of this study was to develop a microtitre-plate assay to study antimicrobial susceptibility of P. aeruginosa based on growth in ASM, which is applicable to both microaerophilic and aerobic conditions.
 An ASM assay was developed in a microtitre plate format. P. aeruginosa biofilms were allowed to develop for 3 days prior to incubation with antimicrobial agents at different concentrations for 24 hours. After biofilm disruption, cell viability was measured by staining with resazurin. This assay was used to ascertain the sessile cell minimum inhibitory concentration (SMIC) of tobramycin for 15 different P. aeruginosa isolates under aerobic and microaerophilic conditions and SMIC values were compared to those obtained with standard broth growth. Whilst there was some evidence for increased MIC values for isolates grown in ASM when compared to their planktonic counterparts, the biggest differences were found with bacteria tested in microaerophilic conditions, which showed a much increased resistance up to a &gt;128 fold, towards tobramycin in the ASM system when compared to assays carried out in aerobic conditions.
 The lack of association between current susceptibility testing methods and clinical outcome has questioned the validity of current methods3. Several in vitro models have been used previously to study P. aeruginosa biofilms7, 8. However, these methods rely on surface attached biofilms, whereas the ASM biofilms resemble those observed in the CF lung9 . In addition, reduced oxygen concentration in the mucus has been shown to alter the behavior of P. aeruginosa2 and affect antibiotic susceptibility10. Therefore using ASM under microaerophilic conditions may provide a more realistic environment in which to study antimicrobial susceptibility.

Use of Artificial Sputum Medium to Test Antibiotic Efficacy Against Pseudomonas aeruginosa in Conditions More Relevant to the Cystic Fibrosis Lung

Current diagnostic antimicrobial susceptibility testing relies on the planktonic growth of isolates in nutrient rich, aerobic conditions. Here, we employ an alternative artificial sputum medium to study antimicrobial susceptibility of Pseudomonas aeruginosa biofilms under both aerobic and microaerophilic conditions more representative of the cystic fibrosis lung.

There  is growing concern about the relevance of in vitro antimicrobial  susceptibility tests when applied to isolates of P. aeruginosa from  cystic ...

Methodologies for Studying B. subtilis Biofilms as a Model for Characterizing Small Molecule Biofilm Inhibitors

This work assesses different methodologies to study the impact of small molecule biofilm inhibitors, such as D-amino acids, on the development and resilience of Bacillus subtilis biofilms. First, methods are presented that select for small molecule inhibitors with biofilm-specific targets in order to separate the effect of the small molecule inhibitors on planktonic growth from their effect on biofilm formation. Next, we focus on how inoculation conditions affect the sensitivity of multicellular, floating B. subtilis cultures to small molecule inhibitors. The results suggest that discrepancies in the reported effects of such inhibitors such as D-amino acids are due to inconsistent pre-culture conditions. Furthermore, a recently developed protocol is described for evaluating the contribution of small molecule treatments towards biofilm resistance to antibacterial substances. Lastly, scanning electron microscopy (SEM) techniques are presented to analyze the three-dimensional spatial arrangement of cells and their surrounding extracellular matrix in a B. subtilis biofilm. SEM facilitates insight into the three-dimensional biofilm architecture and the matrix texture. A combination of the methods described here can greatly assist the study of biofilm development in the presence and absence of biofilm inhibitors, and shed light on the mechanism of action of these inhibitors.

Methodologies for Studying B. subtilis Biofilms as a Model for Characterizing Small Molecule Biofilm Inhibitors

This study presents the development of reproducible methodologies to study biofilm inhibitors and their effects on Bacillus subtilis multicellularity.

This work assesses different methodologies to study the impact of small molecule biofilm inhibitors, such as D-amino acids, on the development and ...

The WinCF Model - An Inexpensive and Tractable Microcosm of a Mucus Plugged Bronchiole to Study the Microbiology of Lung Infections

Many chronic airway diseases result in mucus plugging of the airways. Lungs of an individual with cystic fibrosis are an exemplary case where their mucus-plugged bronchioles create a favorable habitat for microbial colonization. Various pathogens thrive in this environment interacting with each other and driving many of the symptoms associated with CF disease. Like any microbial community, the chemical conditions of their habitat have a significant impact on the community structure and dynamics. For example, different microorganisms thrive in differing levels of oxygen or other solute concentrations. This is also true in the CF lung, where oxygen concentrations are believed to drive community physiology and structure. The methods described here are designed to mimic the lung environment and grow pathogens in a manner more similar to that from which they cause disease. Manipulation of the chemical surroundings of these microbes is then used to study how the chemistry of lung infections governs its microbial ecology. The method, called the WinCF system, is based on artificial sputum medium and narrow capillary tubes meant to provide an oxygen gradient similar to that which exists in mucus-plugged bronchioles. Manipulating chemical conditions, such as the media pH of the sputum or antibiotics pressure, allows for visualization of the microbiological differences in those samples using colored indicators, watching for gas or biofilm production, or extracting and sequencing the nucleic acid contents of each sample.

The mucus plugged airways of cystic fibrosis (CF) patients are an ideal environment for microbial pathogens to thrive. The manuscript describes a novel method for studying the CF lung microbiome in an environment that mimics where they cause disease and how alterations of chemical conditions can drive microbial dynamics.

Many chronic airway diseases result in mucus plugging of the airways. Lungs of an individual with cystic fibrosis are an exemplary case where their ...

Quantifying the Effects of Antimicrobials on In vitro Biofilm Architecture using COMSTAT Software

Biofilms are aggregates of microorganisms that rely on a self-produced matrix of extracellular polymeric substance for protection and structural integrity. The nosocomial pathogen, Pseudomonas aeruginosa, is known to adopt a biofilm mode of growth, causing chronic pulmonary infection in patients with cystic fibrosis (CF). The computer program, COMSTAT, is a useful tool for quantifying antimicrobial-induced changes in P. aeruginosa biofilm architecture by extracting data from three-dimensional confocal images. However, standardized operation of the software is less commonly addressed, which is important for optimal reporting of biofilm behavior and cross-center comparison. Thus, the aim of this protocol is to provide a simple and reproducible framework for quantifying in vitro biofilm structures under varying antimicrobial conditions via COMSTAT. The technique is modeled using a CF P. aeruginosa isolate, grown in the form of biofilm replicates, and exposed to tobramycin and the anti-Psl monoclonal antibody, Psl0096. The step-by-step approach aims to reduce user ambiguity and minimize the chance of overlooking crucial image-processing steps. Specifically, the protocol emphasizes the elimination of subjective variations associated with the manual operation of COMSTAT, including image segmentation and the selection of appropriate quantitative analysis functions. Although this method requires users to spend additional time processing confocal images prior to running COMSTAT, it helps minimize misrepresented biofilm heterogenicity in automated outputs.

Quantifying the Effects of Antimicrobials on In vitro Biofilm Architecture using COMSTAT Software

Antimicrobial-induced changes to Pseudomonas aeruginosa biofilm architecture differ among clinical isolates cultured from patients with cystic fibrosis and chronic pulmonary infection. Following confocal microscopy, COMSTAT software can be utilized to quantify variations in biofilm architecture (e.g., surface area, thickness, biomass) for individual isolates to assess the efficacy of anti-infective agents.

Biofilms are aggregates of microorganisms that rely on a self-produced matrix of extracellular polymeric substance for protection and structural ...

Antibiotic Efficacy Testing in an Ex vivo Model of Pseudomonas aeruginosa and Staphylococcus aureus Biofilms in the Cystic Fibrosis Lung

The effective prescription of antibiotics for the bacterial biofilms present within the lungs of individuals with cystic fibrosis (CF) is limited by a poor correlation between antibiotic susceptibility testing (AST) results using standard diagnostic methods (e.g., broth microdilution, disk diffusion, or Etest) and clinical outcomes after antibiotic treatment. Attempts to improve AST by the use of off-the-shelf biofilm growth platforms show little improvement in results. The limited ability of in vitro biofilm systems to mimic the physicochemical environment of the CF lung and, therefore bacterial physiology and biofilm architecture, also acts as a brake on the discovery of novel therapies for CF infection. Here, we present a protocol to perform AST of CF pathogens grown as mature, in vivo-like biofilms in an ex vivo CF lung model comprised of pig bronchiolar tissue and synthetic CF sputum (ex vivo&#160;pig lung, EVPL).
Several in vitro&#160;assays exist for biofilm susceptibility testing, using either standard laboratory medium or various formulations of synthetic CF sputum in microtiter plates. Both growth medium and biofilm substrate (polystyrene plate vs. bronchiolar tissue) are likely to affect biofilm antibiotic tolerance. We show enhanced tolerance of clinical Pseudomonas aeruginosa and Staphylococcus aureus isolates in the ex vivo model; the effects of antibiotic treatment of biofilms is not correlated with the minimum inhibitory concentration (MIC) in standard microdilution assays or a sensitive/resistant classification in disk diffusion assays.
The ex vivo platform could be used for bespoke biofilm AST of patient samples and as an enhanced testing platform for potential antibiofilm agents during pharmaceutical research and development. Improving the prescription or acceleration of antibiofilm drug discovery through the use of more in vivo-like testing platforms could drastically improve health outcomes for individuals with CF, as well as reduce the costs of clinical treatment and discovery research.

Antibiotic Efficacy Testing in an Ex vivo Model of Pseudomonas aeruginosa and Staphylococcus aureus Biofilms in the Cystic Fibrosis Lung

This workflow can be used to perform antibiotic susceptibility testing using an established&#160;ex vivo model of bacterial biofilm in the lungs of individuals with cystic fibrosis. Use of this model could enhance the clinical validity of MBEC (minimal biofilm eradication concentration) assays.

The effective prescription of antibiotics for the bacterial biofilms present within the lungs of individuals with cystic fibrosis (CF) is limited by a ...

Adaptable CF Model for Antimicrobial Testing and Microbial Dynamics Analysis

Development of a Polymicrobial Colony Biofilm Model to Test Antimicrobials in Cystic Fibrosis

A range of bacteria biofilm models exist for the testing of antibiotics. However, many of these are limited to a single experimental output, such as colony-forming units or metabolic activity. Furthermore, many biofilm models do not reflect the biological and physiochemical properties of the human host environment. This is an important issue in many conditions, but most noticeably in cystic fibrosis (CF). A large proportion of people with CF suffer from both chronic and intermittent infections, and in vitro, antibiotic susceptibility testing poorly correlates with patient treatment outcomes. Some biofilm models incorporate CF lung-relevant media, including synthetic sputum mimics, but do not consider the polymicrobial nature of the environment, which alters biofilm architecture, physiology, and the way microbes respond to treatment. The solid-air interface colony biofilm model described here is highly adaptable and incorporates both CF-relevant media and a polymicrobial context. This model can also be used for mid-throughput screening of antimicrobials and to study their effect on polymicrobial dynamics. Output measurements from the model can be colony-forming units, metabolic activity, and confocal microscopy analysis. The model can easily be adapted to different microorganisms, media, temperatures, and variable oxygen conditions and can be used to test a wide range of chemical, biological, and physical treatments.

This methodology allows for the establishment of a polymicrobial biofilm model in cystic fibrosis for antimicrobial sensitivity testing in research and clinical laboratories. This model provides accurate and reliable results over a range of outputs.

A range of bacteria biofilm models exist for the testing of antibiotics. However, many of these are limited to a single experimental output, such as ...

Developing and Assessing Pellicle Biofilms in Mycobacteria

Growing Mycobacterial Biofilm as a Model to Study Antimicrobial Resistance

Many bacteria thrive in intricate natural communities, exhibiting key attributes of multicellularity such as communication, cooperation, and competition. The most prevalent manifestation of bacterial multicellular behavior is the formation of biofilms, often linked to pathogenicity. Biofilms offer a haven against antimicrobial agents, fostering the emergence of antimicrobial resistance. The conventional practice of cultivating bacteria in shake flask liquid cultures fails to represent their proper physiological growth in nature, consequently limiting our comprehension of their intricate dynamics. Notably, the metabolic and transcriptional profiles of bacteria residing in biofilms closely resemble those of naturally growing cells. This parallelism underscores the significance of biofilms as an ideal model for foundational and translational research. This article focuses on utilizing Mycobacterium smegmatis as a model organism to illustrate a technique for cultivating pellicle biofilms. The approach is adaptable to various culture volumes, facilitating its implementation for diverse experimental objectives such as antimicrobial studies. Moreover, the method&#39;s design enables the qualitative or quantitative evaluation of the biofilm-forming capabilities of different mycobacterial species with minor adjustments.

Author Spotlight: Advancing Mycobacterial Biofilm Protocols for Enhanced Bacterial Metabolism Research

This protocol describes a robust method for developing pellicle biofilm. The method is scalable to different culture volumes, allowing easy adoption for various experimental objectives. The method's design enables qualitative or quantitative assessment of the biofilm-forming potential of several mycobacterial species.

Many bacteria thrive in intricate natural communities, exhibiting key attributes of multicellularity such as communication, cooperation, and competition. ...

Visualizing the Effects of Sputum on Biofilm Development Using a Chambered Coverglass Model

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Use of Artificial Sputum Medium to Test Antibiotic Efficacy Against Pseudomonas aeruginosa in Conditions More Relevant to the Cystic Fibrosis Lung

Methodologies for Studying B. subtilis Biofilms as a Model for Characterizing Small Molecule Biofilm Inhibitors

The WinCF Model - An Inexpensive and Tractable Microcosm of a Mucus Plugged Bronchiole to Study the Microbiology of Lung Infections

Quantifying the Effects of Antimicrobials on In vitro Biofilm Architecture using COMSTAT Software

Antibiotic Efficacy Testing in an Ex vivo Model of Pseudomonas aeruginosa and Staphylococcus aureus Biofilms in the Cystic Fibrosis Lung

Development of a Polymicrobial Colony Biofilm Model to Test Antimicrobials in Cystic Fibrosis

Growing Mycobacterial Biofilm as a Model to Study Antimicrobial Resistance