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>

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	<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. 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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 products creates inherent variability on the experiment due to the fact that the sputum of each patient has a unique microbiome. To adjust for this, we have used pooled sputum samples to avoid patient specific results. Additionally, the choice of appropriate media is important when using any model system. Standard media for biofilm growth of the intended organism are recommended for initial setup of the system. If the goal of the experiment is to identify how exogenous products are affecting biofilm formation, a nutrient rich media that provides adequate biofilm formation is suggested. This will allow sufficient nutrition for growth while determining how exogenous factors may affect the biofilm. Other media, such as minimal or defined media, can be used to better mimic certain conditions. Other media have been used with good results in this system (data not shown). The attachment of the biofilms to the chambered coverglass is robust, however great care must be taken when removing/adding media or during washing steps of the biofilms to prevent disrupting the biofilms.
The use of the live-dead stain as per manufacturer&#39;s protocol has yielded good results for the system described. A number of factors can affect the fluorescence ratio of the images (including dye uptake of bacteria, relative density of biofilm and detector gain settings), however, this method should relate to what is observed in the images. Other measures may be used to represent the relative amount of dead/live biofilm, such as the biomass from the dead cells as a ratio of the total biomass present in the biofilm (as derived from COMSTAT). Using bacterial counts to confirm biofilm viability in repeated experiments is recommended to confirm the visual observations of this model. Due to inherent heterogeneity of biofilms, multiple images from each chamber and multiple chambers should be used for each condition in an experiment. This adds to the cost and duration of these experiments.
The acquisition of images is important prior to the analysis of data from these experiments. Care must be taken to not over saturate images and when determining the microscope setup. Depending on the level of detail required and the microscope available, a number of different objectives (10X, 25X, 40X and 63X) can be used to acquire images, though we find that 25X objective gives better images. The thickness of the Z-stack can also affect overall image quality and level of detail. Having images taken every 0.5-1 &#956;m seems to provide clear images at 25X objective, while keeping the Z-stack images at a size that can be analyzed by COMSTAT on standard computer systems.
These experiments are more costly and time consuming than other attachment assays, and cannot be done in a high throughput manner. In this procedure, bacteria attach to a borosilicate surface, which is not reflective of an in vivo condition and may affect biofilm formation and development. However, they provide additional information and can generate hypotheses for mechanism related to biofilm antibiotic resistance and physiological response to exogenous signal. If the goal of the experiment is to understand how biofilms change in response to different factors, rather than identifying anti-biofilm compounds using high-throughput methods for instance, the additional information gained using this technique makes the method worthwhile. Thus the current method is a significant advancement over previous limited attachment assays such as the crystal violet assay, which is most commonly used to study biofilms.
Critical steps to this procedure include: 1) Ensuring timely processing of sputum samples to avoid degradation; 2) Being gentle with media changes on the biofilms to avoid disruption of the biofilm and 3) Doing repeated measurements of biofilm imaging to ensure an accurate representation of the biofilm thickness due to the heterogeneity of biofilm formation.
Once the system is set-up for a given bacterial species, one can test a number of different conditions, including the effects of exogenous factors on multiple clinical isolates. This system has been used to study the effect of antibiotics on biofilms exposed to human sputum16 and to compare highly resistant and intermediately resistant clinical isolates.17 Modifications to the chambered coverglass, such as coating the bottom with mucin or collagen micro-scaffold (e.g., puracol), can further extend the range of experiments possible. It may be possible to adapt this system to study direct interactions, such as those between epithelial cells and bacteria, or between different bacterial species. This is an expansion of the model described by Jurcisek et al.20 The method uses slide chamber growth similar to that described here and uses formalin to fix biofilms prior to visualization. Alternatively, in this method we visualize biofilms immediately after staining and do not use a fixative. In addition, we add exogenous factors to test the effect of antibiotic on biofilms. This model thus has the potential to considerably further our understanding of bacterial biofilms in human disease.

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 border="0" cellpadding="0" cellspacing="0" width="1270">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:247px;">Lab-Tek II Chambered coverglass, #1.5 borosilicate, 8-well</td>
			<td style="width:159px;">Thermo Sicher Scientific</td>
			<td style="width:136px;">155409</td>
			<td style="width:729px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:247px;">Filmtracer Live/Dead Biofilm Viabilty Kit</td>
			<td style="width:159px;">Thermo Fisher Scientific</td>
			<td style="width:136px;">L10316</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:247px;">Blood agar plates</td>
			<td style="width:159px;">Thermo Fisher Scientific</td>
			<td style="width:136px;">R10215</td>
			<td>Confirming viability via CFU counts or selecting colonies for innoculation</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:247px;">COMSTAT</td>
			<td style="width:159px;">Availble software online</td>
			<td style="width:136px;"></td>
			<td>COMSTAT is software to analyze biofilm images. Available www.comstat.dk&#160;</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:247px;">Millers LB Broth</td>
			<td style="width:159px;">Thermo Fisher Scientific</td>
			<td>12780-052</td>
			<td style="width:729px;">Standard media for overnight gowth/biofilm growth</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Millex-GV Syringe Filters</td>
			<td style="width:159px;">Millipore</td>
			<td>SLGV013SL</td>
			<td>Filtering of sputum supernants</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:247px;">Phosphate Buffered Saline (Dulbecco A)</td>
			<td style="width:159px;">Oxoid</td>
			<td style="width:136px;">BR0014G</td>
			<td>Washing of biofilm chambers after media removal</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Zeiss AxioVert 200M</td>
			<td style="width:159px;">Carl Zeiss</td>
			<td style="width:136px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Hamamatsu C9100-13 EM-CCD</td>
			<td style="width:159px;">QS Technologies Inc.</td>
			<td style="width:136px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Spectral Borealis</td>
			<td style="width:159px;">Qs Technologies Inc.</td>
			<td style="width:136px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Perkin Elmer Volocity</td>
			<td style="width:159px;">QS Technologies Inc.</td>
			<td style="width:136px;"></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 (Figure 2A, lower panels).16 These images can be analyzed using COMSTAT software to obtain key biofilm matrices, including average thickness of the biofilm, total biomass and surface coverage. This is reflected in an overall increase in biofilm thickness (Figures 2B, and 3).16 The effects of antibiotics on biofilms in the presence sputum is shown in Figure 3. By visualizing the changes in biofilm development, one can better appreciate how different factors can affect biofilm growth, to a much better extent than traditional biofilm assays, such as crystal violet staining.
<img alt="Figure 1" src="/files/ftp_upload/54819/54819fig1.jpg" /> 
Figure 1: Overall design of experiment. Flow diagram of basic protocol. An overnight (O/N) culture is diluted 1/1,000 and allowed to grow to a final OD600 of 0.5. This is further diluted 1/1,000 and 200 &#181;l is seeded into well of chambered coverglass and allowed to attach for 3-4 hr. Following this, media is removed and replaced with fresh media. Biofilms are allowed to grow for desired time. Media, exogenous products or antibiotics can be added to the biofilms. Following growth, media is removed, biofilms are stained and confocal imaging is performed. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54819/54819fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" src="/files/ftp_upload/54819/54819fig2.jpg" /> 
Figure 2: Representative images of biofilm development following exposure to sputum filtrates. (A) Representative images of Burkholderia cepacia complex (BCC) clinical isolates following 48 hr of growth in chambered coverglass with media alone (top panels) or in the presence of 10% sputum filtrates (lower panels) followed by staining with biofilm viability kit. 1 scale unit represent 19.68 &#956;m. (B-C) Average thickness of isolates (B) and dead:live ratio (C) of multiple images of BCC isolates grown for 48 hr in slide chambers in the absence (white bars) or presence (black bars) of sputum filtrates . Each bar represents the mean of 45 images plotted with the standard error of the mean. **p &#60;0.001 compared to control (media alone) using Kruskal-Wallis test. Figure adapted from Kennedy et al.16 <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54819/54819fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" src="/files/ftp_upload/54819/54819fig3.jpg" /> 
Figure 3: Representative images of antibiotic treatment on biofilms exposed to sputum filtrate. (A) Images of Burkholderia vietnamiensis clinical isolates following 48 hr of growth in chambered coverglass with media alone (left) or in the presence of 10% sputum filtrates (right) with or without 1,000 &#956;g/m of tobramycin. Biofilms were grown for 24 hr in media alone or media supplemented with 10% (v/v) sputum filtrates. After 24 hr, media was removed and replaced with media (+/- sputum) containing antibiotics. 1 scale unit represent 19.68 &#956;m. (B-C) Average thickness of isolates (B) and dead:live ratio (C) of multiple images (n = 9) of B. vietnamiensis isolates grown for 48 hr in slide chambers in the absence or presence of sputum filtrates . Each bar represents the mean of 45 images plotted with the standard error of the mean. **p &#60;0.001 compared to control (0 &#181;g/ml) using Kruskal-Wallis test. Figure adapted from Kennedy et al.16 <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54819/54819fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

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 ...

visualizing-effects-sputum-on-biofilm-development-using-chambered

Nanyang Technological University

Research

JoVE Journal

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

Microtiter Dish Biofilm Formation Assay

Biofilms are communities of microbes attached to surfaces, which can be found in medical, industrial and natural settings. In fact, life in a biofilm probably represents the predominate mode of growth for microbes in most environments. Mature biofilms have a few distinct characteristics. Biofilm microbes are typically surrounded by an extracellular matrix that provides structure and protection to the community. Microbes growing in a biofilm also have a characteristic architecture generally comprised of macrocolonies (containing thousands of cells) surrounded by fluid-filled channels. Biofilm-grown microbes are also notorious for their resistance to a range of antimicrobial agents including clinically relevant antibiotics.
The microtiter dish assay is an important tool for the study of the early stages in biofilm formation, and has been applied primarily for the study of bacterial biofilms, although this assay has also been used to study fungal biofilm formation. Because this assay uses static, batch-growth conditions, it does not allow for the formation of the mature biofilms typically associated with flow cell systems. However, the assay has been effective at identifying many factors required for initiation of biofilm formation (i.e, flagella, pili, adhesins, enzymes involved in cyclic-di-GMP binding and metabolism) and well as genes involved in extracellular polysaccharide production. Furthermore, published work indicates that biofilms grown in microtiter dishes do develop some properties of mature biofilms, such a antibiotic tolerance and resistance to immune system effectors.
This simple microtiter dish assay allows for the formation of a biofilm on the wall and/or bottom of a microtiter dish. The high throughput nature of the assay makes it useful for genetic screens, as well as testing biofilm formation by multiple strains under various growth conditions. Variants of this assay have been used to assess early biofilm formation for a wide variety of microbes, including but not limited to, pseudomonads, Vibrio cholerae, Escherichia coli, staphylocci, enterococci, mycobacteria and fungi.
In the protocol described here, we will focus on the use of this assay to study biofilm formation by the model organism Pseudomonas aeruginosa. In this assay, the extent of biofilm formation is measured using the dye crystal violet (CV). However, a number of other colorimetric and metabolic stains have been reported for the quantification of biofilm formation using the microtiter plate assay. The ease, low cost and flexibility of the microtiter plate assay has made it a critical tool for the study of biofilms.

The assay describes a rapid means to measure early biofilm formation in bacteria and fungi. This method uses a microtiter plate as the substratum for microbial biofilm formation, and the biofilm is visualized using crystal violet strain. The assay provides either a qualitative or quantitative assay for early biofilm formation.

Biofilms are communities of microbes attached to surfaces, which can be found in medical, industrial and natural settings.  In fact, life in a biofilm ...

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. ...

A Microplate Assay to Assess Chemical Effects on RBL-2H3 Mast Cell Degranulation: Effects of Triclosan without Use of an Organic Solvent

Mast cells play important roles in allergic disease and immune defense against parasites. Once activated (e.g. by an allergen), they degranulate, a process that results in the exocytosis of allergic mediators. Modulation of mast cell degranulation by drugs and toxicants may have positive or adverse effects on human health. Mast cell function has been dissected in detail with the use of rat basophilic leukemia mast cells (RBL-2H3), a widely accepted model of human mucosal mast cells3-5. Mast cell granule component and the allergic mediator &#946;-hexosaminidase, which is released linearly in tandem with histamine from mast cells6, can easily and reliably be measured through reaction with a fluorogenic substrate, yielding measurable fluorescence intensity in a microplate assay that is amenable to high-throughput studies1. Originally published by Naal et al.1, we have adapted this degranulation assay for the screening of drugs and toxicants and demonstrate its use here.
Triclosan is a broad-spectrum antibacterial agent that is present in many consumer products and has been found to be a therapeutic aid in human allergic skin disease7-11, although the mechanism for this effect is unknown. Here we demonstrate an assay for the effect of triclosan on mast cell degranulation. We recently showed that triclosan strongly affects mast cell function2. In an effort to avoid use of an organic solvent, triclosan is dissolved directly into aqueous buffer with heat and stirring, and resultant concentration is confirmed using UV-Vis spectrophotometry (using &#949;280 = 4,200 L/M/cm)12. This protocol has the potential to be used with a variety of chemicals to determine their effects on mast cell degranulation, and more broadly, their allergic potential.

Mast cell degranulation, the release of allergic mediators, is important in allergy, asthma, and parasite defense. Here we demonstrate techniques1 for assessing effects of drugs and toxicants on degranulation, methodology recently utilized to exhibit the powerful inhibitory effect of antibacterial agent triclosan2.

Mast cells play important roles in allergic disease and immune defense against parasites. Once activated (e.g. by an allergen), they degranulate, a ...

Using Click Chemistry to Measure the Effect of Viral Infection on Host-Cell RNA Synthesis

Many RNA viruses have evolved the ability to inhibit host cell transcription as a means to circumvent cellular defenses. For the study of these viruses, it is therefore important to have a quick and reliable way of measuring transcriptional activity in infected cells. Traditionally, transcription has been measured either by incorporation of radioactive nucleosides such as 3H-uridine followed by detection via autoradiography or scintillation counting, or incorporation of halogenated uridine analogs such as 5-bromouridine (BrU) followed by detection via immunostaining. The use of radioactive isotopes, however, requires specialized equipment and is not feasible in a number of laboratory settings, while the detection of BrU can be cumbersome and may suffer from low sensitivity.
The recently developed click chemistry, which involves a copper-catalyzed triazole formation from an azide and an alkyne, now provides a rapid and highly sensitive alternative to these two methods. Click chemistry is a two step process in which nascent RNA is first labeled by incorporation of the uridine analog 5-ethynyluridine (EU), followed by detection of the label with a fluorescent azide. These azides are available as several different fluorophores, allowing for a wide range of options for visualization.
This protocol describes a method to measure transcriptional suppression in cells infected with the Rift Valley fever virus (RVFV) strain MP-12 using click chemistry. Concurrently, expression of viral proteins in these cells is determined by classical intracellular immunostaining. Steps 1 through 4 detail a method to visualize transcriptional suppression via fluorescence microscopy, while steps 5 through 8 detail a method to quantify transcriptional suppression via flow cytometry. This protocol is easily adaptable for use with other viruses.

This method describes the use of click chemistry to measure changes in host cell transcription after infection with the Rift Valley fever virus (RVFV) strain MP-12. Results can be visualized qualitatively via fluorescence microscopy or obtained quantitatively through flow cytometry. This method is adaptable for use with other viruses.

Many RNA viruses have evolved the ability to inhibit host cell transcription as a means to circumvent cellular defenses. For the study of these viruses, ...

Investigating the Effects of Probiotics on Pneumococcal Colonization Using an In Vitro Adherence Assay

Adherence of Streptococcus pneumoniae (the pneumococcus) to the epithelial lining of the nasopharynx can result in colonization and is considered a prerequisite for pneumococcal infections such as pneumonia and otitis media. In vitro adherence assays can be used to study the attachment of pneumococci to epithelial cell monolayers and to investigate potential interventions, such as the use of probiotics, to inhibit pneumococcal&#160;colonization.&#160;The protocol described here is used to investigate the effects of the probiotic Streptococcus salivarius on the adherence of pneumococci to the human epithelial cell line CCL-23 (sometimes referred to as HEp-2 cells). The assay involves three main steps: 1) preparation of epithelial and bacterial cells, 2) addition of bacteria to epithelial cell monolayers, and 3) detection of adherent pneumococci by viable counts (serial dilution and plating) or quantitative real-time PCR (qPCR). This technique is relatively straightforward and does not require specialized equipment other than a tissue culture setup. The assay can be used to test other probiotic species and/or potential inhibitors of pneumococcal colonization and can be easily modified to address other scientific questions regarding pneumococcal adherence and invasion.

Investigating the Effects of Probiotics on Pneumococcal Colonization Using an In Vitro Adherence Assay

In vitro adherence assays can be used to study the attachment of Streptococcus pneumoniae to epithelial cell monolayers and to investigate potential interventions such as the use of probiotics for inhibiting pneumococcal colonization.

Adherence of Streptococcus pneumoniae (the pneumococcus) to the epithelial lining of the nasopharynx can result in colonization and is considered a ...

Analyzing the Effects of Stromal Cells on the Recruitment of Leukocytes from Flow

Stromal cells regulate the recruitment of circulating leukocytes during inflammation through cross-talk with neighboring endothelial cells. Here we describe two in vitro &#8220;vascular&#8221; models for studying the recruitment of circulating neutrophils from flow by inflamed endothelial cells. A major advantage of these models is the ability to analyze each step in the leukocyte adhesion cascade in order, as would occur in vivo. We also describe how both models can be adapted to study the role of stromal cells, in this case mesenchymal stem cells (MSC), in regulating leukocyte recruitment.
Primary endothelial cells were cultured alone or together with human MSC in direct contact on Ibidi microslides or on opposite sides of a Transwell filter for 24 hr. Cultures were stimulated with tumor necrosis factor alpha (TNF&#945;) for 4 hr and incorporated into a flow-based adhesion assay. A bolus of neutrophils was perfused over the endothelium for 4 min. The capture of flowing neutrophils and their interactions with the endothelium was visualized by phase-contrast microscopy.
In both models, cytokine-stimulation increased endothelial recruitment of flowing neutrophils in a dose-dependent manner. Analysis of the behavior of recruited neutrophils showed a dose-dependent decrease in rolling and a dose-dependent increase in transmigration through the endothelium. In co-culture, MSC suppressed neutrophil adhesion to TNF&#945;-stimulated endothelium.
Our flow based-adhesion models mimic the initial phases of leukocyte recruitment from the circulation. In addition to leukocytes, they can be used to examine the recruitment of other cell types, such as therapeutically administered MSC or circulating tumor cells. Our multi-layered co-culture models have shown that MSC communicate with endothelium to modify their response to pro-inflammatory cytokines, altering the recruitment of neutrophils. Further research using such models is required to fully understand how stromal cells from different tissues and conditions (inflammatory disorders or cancer) influence the recruitment of leukocytes during inflammation.

The ability of inflamed endothelium to recruit leukocytes from flow is regulated by mesenchymal stromal cells. We describe two in vitro models incorporating primary human cells that can be used to assess neutrophil recruitment from flow and examine the role that mesenchymal stromal cells play in regulating this process.

Stromal cells regulate the recruitment of circulating leukocytes during inflammation through cross-talk with neighboring endothelial cells. Here we ...

Flow Cytometric Analysis of Particle-bound Bet v 1 Allergen in PM10

Flow cytometry is a method widely used to quantify suspended solids such as cells or bacteria in a size range from 0.5 to several tens of micrometers in diameter. In addition to a characterization of forward and sideward scatter properties, it enables the use of fluorescent labeled markers like antibodies to detect respective structures. Using indirect antibody staining, flow cytometry is employed here to quantify birch pollen allergen (precisely Bet v 1)-loaded particles of 0.5 to 10 &#181;m in diameter in inhalable particulate matter (PM10, particle size &#8804;10 &#181;m in diameter). PM10 particles may act as carriers of adsorbed allergens possibly transporting them to the lower respiratory tract, where they could trigger allergic reactions.
So far the allergen content of PM10 has been studied by means of enzyme linked immunosorbent assays (ELISAs) and scanning electron microscopy. ELISA measures the dissolved and not the particle-bound allergen. Compared to scanning electron microscopy, which can visualize allergen-loaded particles, flow cytometry may additionally quantify them. As allergen content of ambient air can deviate from birch pollen count, allergic symptoms might perhaps correlate better with allergen exposure than with pollen count. In conjunction with clinical data, the presented method offers the opportunity to test in future experiments whether allergic reactions to birch pollen antigens are associated with the Bet v 1 allergen content of PM10 particles &#62;0.5 &#181;m.

Here, we present a protocol to quantify allergen-loaded particles by flow cytometry. Ambient particulate matter particles may act as carriers of adsorbed allergens. We show here that flow cytometry, a method widely used to characterize suspended solids &#62;0.5 &#181;m in diameter, can be used to measure these allergen-loaded particles.

Flow cytometry is a method widely used to quantify suspended solids such as cells or bacteria in a size range from 0.5 to several tens of micrometers in ...

Real-time Imaging and Quantification of Fungal Biofilm Development Using a Two-Phase Recirculating Flow System

In oropharyngeal candidiasis, members of the genus Candida must adhere to and grow on the oral mucosal surface while under the effects of salivary flow. While models for the growth under flow have been developed, many of these systems are expensive, or do not allow imaging while the cells are under flow. We have developed a novel apparatus that allows us to image the growth and development of Candida albicans cells under flow and in real-time. Here, we detail the protocol for the assembly and use of this flow apparatus, as well as the quantification of data that are generated. We are able to quantify the rates that the cells attach to and detach from the slide, as well as to determine a measure of the biomass on the slide over time. This system is both economical and versatile, working with many types of light microscopes, including inexpensive benchtop microscopes, and is capable of extended imaging times compared to other flow systems. Overall, this is a low-throughput system that can provide highly detailed real-time information on the biofilm growth of fungal species under flow.

We describe the assembly, operation, and cleaning of a flow apparatus designed to image fungal biofilm formation in real time while under flow. We also provide and discuss quantitative algorithms to be used on the acquired images.

In oropharyngeal candidiasis, members of the genus Candida must adhere to and grow on the oral mucosal surface while under the effects of salivary flow. ...

An In Vitro Batch-culture Model to Estimate the Effects of Interventional Regimens on Human Fecal Microbiota

The emerging role of the gut microbiome in several human diseases demands a breakthrough of new tools, techniques and technologies. Such improvements are needed to decipher the utilization of microbiome modulators for human health benefits. However, the large-scale screening and optimization of modulators to validate microbiome modulation and predict related health benefits may be practically difficult due to the need for large number of animals and/or human subjects. To this end, in vitro or ex vivo models can facilitate preliminary screening of microbiome modulators. Herein, it is optimized and demonstrated an ex vivo fecal microbiota culture system that can be used for examining the effects of various interventions of gut microbiome modulators including probiotics, prebiotics and other food ingredients, aside from nutraceuticals and drugs, on the diversity and composition of the human gut microbiota. Inulin, one of the most widely studied prebiotic compounds and microbiome modulators, is used as an example here to examine its effect on the healthy fecal microbiota composition and its metabolic activities, such as fecal pH and the fecal levels of organic acids including lactate and short-chain fatty acids (SCFAs). The protocol may be useful for studies aimed at estimating the effects of different interventions of modulators on fecal microbiota profiles and at predicting their health impacts.

This protocol describes an in vitro batch-culture fermentation system of human fecal microbiota, using inulin (a well-known prebiotic and one of the most widely studied microbiota modulators) to demonstrate the use of this system in estimating effects of specific interventions on fecal microbiota composition and metabolic activities.

The emerging role of the gut microbiome in several human diseases demands a breakthrough of new tools, techniques and technologies. Such improvements are ...

Mechanistic Insight into the Development of TNBS-Mediated Intestinal Fibrosis and Evaluating the Inhibitory Effects of Rapamycin

Significant studies have been carried out to understand effective management of intestinal fibrosis. However, the lack of better knowledge of fibrosis has hindered the development of a preventative drug. Primarily, finding a suitable animal model is challenging in understanding the mechanism of Crohn&#39;s-associated intestinal fibrosis pathology. Here, we adopted an effective method where TNBS chemical exposure to mice rectums produces substantially deep ulceration and chronic inflammation, and the mice then chronically develop intestinal fibrosis. Also, we describe a technique where a rapamycin injection shows inhibitory effects on TNBS-mediated fibrosis in the mouse model. To assess the underlying mechanism of fibrosis, we methodically discuss a procedure for purifying Cx3Cr1+ cells from the lamina propria of TNBS-treated and control mice. This detailed protocol will be helpful to researchers who are investigating the mechanism of fibrosis and pave the path to find a better therapeutic invention for Crohn&#39;s-associated intestinal fibrosis.

In this study, we describe a detailed procedure of TNBS-mediated intestinal fibrosis, which exhibits comparable pathophysiology to Crohn&#39;s fibrosis. We also discuss this approach in light of rapamycin facilitated inhibitory effects on intestinal fibrosis.

Significant studies have been carried out to understand effective management of intestinal fibrosis. However, the lack of better knowledge of fibrosis has ...