Name: discovery of new intracellular pathogens by amoebal coculture and amoebal enrichment approaches
Uploaded: 2013-10-27T23:00:00
Description: Watch this Scientific Journal Video about Discovery of New Intracellular Pathogens by Amoebal Coculture and Amoebal Enrichment Approaches at JoVE.com

We thank Pr. Bernard La Scola for helpful technical advices and interesting discussion on amoebal coculture and amoebal enrichment. We also thank Dr Vincent Thomas for his help in implementing the technique in our laboratory.

1. Amoebal Coculture
1.1 Sample preparation
<ol>
	<li>Environmental sample
	<ol>
		<li>Water samples 
		Filter the water sample (500 ml to 1 L) through a 0.22 &#956;m pore size membrane. Then, shake the membrane in Page&#39;s amoeba saline medium PAS (120 mg of NaCl, 4 mg of MgSO4&#8226;7H2O, 4 mg of CaCl2&#8226;2H2O, 142 mg of Na2HPO4, and 136 mg of KH2PO4 in 1 L of di...

<ol>
	<li>Fraser, D. W., 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=Legionnaires'+disease:+description+of+an+epidemic+of+pneumonia.">Legionnaires' disease: description of an epidemic of pneumonia.</a> New Engl. J. Med. 297, 1189-1197 (1977).</li><li>McDade, J. E., 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=Legionnaires'+disease:+isolation+of+a+bacterium+and+demonstration+of+its+role+in+other+respiratory+disease.">Legionnaires' disease: isolation of a bacterium and demonstration of its role in other respiratory disease.</a> New Engl. J. Med. 297, 1197-1203 (1977).</li><li>Rowbotham, T. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preliminary+report+on+the+pathogenicity+of+Legionella+pneumophila+for+freshwater+and+soil+amoebae.">Preliminary report on the pathogenicity of Legionella pneumophila for freshwater and soil amoebae.</a> J. Clin. Pathol. 33, 1179-1183 (1980).</li><li>Rodriguez-Zaragoza, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ecology+of+free-living+amoebae.">Ecology of free-living amoebae.</a> Crit. Rev. Microbiol. 20, 225-241 (1994).</li><li>Booton, G. C., Visvesvara, G. S., Byers, T. J., Kelly, D. J., Fuerst, P. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+and+distribution+of+Acanthamoeba+species+genotypes+associated+with+nonkeratitis+infections.">Identification and distribution of Acanthamoeba species genotypes associated with nonkeratitis infections.</a> J Clin. Microbiol. 43, 1689-1693 (2005).</li><li>Brussow, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bacteria+between+protists+and+phages:+from+antipredation+strategies+to+the+evolution+of+pathogenicity.">Bacteria between protists and phages: from antipredation strategies to the evolution of pathogenicity.</a> Molecular microbiology. 65, 583-589 (2007).</li><li>Greub, G., Raoult, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microorganisms+resistant+to+free-living+amoebae.">Microorganisms resistant to free-living amoebae.</a> Clin. Microbiol. Rev. 17, 413-433 (2004).</li><li>Thomas, V., McDonnell, G., Denyer, S. P., Maillard, J. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Free-living+amoebae+and+their+intracellular+pathogenic+microorganisms:+risks+for+water+quality.">Free-living amoebae and their intracellular pathogenic microorganisms: risks for water quality.</a> FEMS Microbiol Rev. 34, 231-259 (2010).</li><li>Birtles, R. J., Rowbotham, T. J., Storey, C., Marrie, T. J., Raoult, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chlamydia-like+obligate+parasite+of+free-living+amoebae.">Chlamydia-like obligate parasite of free-living amoebae.</a> Lancet. 349, 925-926 (1997).</li><li>Amann, R., 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=Obligate+intracellular+bacterial+parasites+of+acanthamoebae+related+to+Chlamydia+spp.">Obligate intracellular bacterial parasites of acanthamoebae related to Chlamydia spp.</a> Appl. Environ. Microbiol. 63, 115-121 (1997).</li><li>Birtles, R. 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=Candidatus+Odyssella+thessalonicensis'+gen.+nov.,+sp.+nov.,+an+obligate+intracellular+parasite+of+Acanthamoeba+species.">Candidatus Odyssella thessalonicensis' gen. nov., sp. nov., an obligate intracellular parasite of Acanthamoeba species.</a> Int. J. Syst. Evol. Microbiol. 50, 63-72 (2000).</li><li>Thomas, V., Casson, N., Greub, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Criblamydia+sequanensis,+a+new+intracellular+Chlamydiales+isolated+from+Seine+river+water+using+amoebal+co-culture.">Criblamydia sequanensis, a new intracellular Chlamydiales isolated from Seine river water using amoebal co-culture.</a> Environ. Microbiol. 8, 2125-2135 (2006).</li><li>Pagnier, I., Raoult, D., La Scola, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+and+identification+of+amoeba-resisting+bacteria+from+water+in+human+environment+by+using+an+Acanthamoeba+polyphaga+co-culture+procedure.">Isolation and identification of amoeba-resisting bacteria from water in human environment by using an Acanthamoeba polyphaga co-culture procedure.</a> Environ. Microbiol. 10, 1135-1144 (2008).</li><li>Thomas, V., Loret, J. F., Jousset, M., Greub, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biodiversity+of+amoebae+and+amoebae-resisting+bacteria+in+a+drinking+water+treatment+plant.">Biodiversity of amoebae and amoebae-resisting bacteria in a drinking water treatment plant.</a> Environ. Microbiol. 10, 2728-2745 (2008).</li><li>Corsaro, D., 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=Novel+Chlamydiales+strains+isolated+from+a+water+treatment+plant.">Novel Chlamydiales strains isolated from a water treatment plant.</a> Environ. Microbiol. 11, 188-200 (2009).</li><li>Goy, G., Croxatto, A., Greub, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Waddlia+chondrophila+enters+and+multiplies+within+human+macrophages.">Waddlia chondrophila enters and multiplies within human macrophages.</a> Microbes Infect. 10, 556-562 (2008).</li><li>Kebbi-Beghdadi, C., Cisse, O., Greub, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Permissivity+of+Vero+cells,+human+pneumocytes+and+human+endometrial+cells+to+Waddlia+chondrophila.">Permissivity of Vero cells, human pneumocytes and human endometrial cells to Waddlia chondrophila.</a> Microbes Infect. 13, 566-574 (2011).</li><li>Kebbi-Beghdadi, C., Batista, C., Greub, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Permissivity+of+fish+cell+lines+to+three+Chlamydia-related+bacteria:+Waddlia+chondrophila,+Estrella+lausannensis+and+Parachlamydia+acanthamoebae.">Permissivity of fish cell lines to three Chlamydia-related bacteria: Waddlia chondrophila, Estrella lausannensis and Parachlamydia acanthamoebae.</a> FEMS Immunol. Med. Microbiol. 63, 339-345 (2011).</li><li>Fry, N. K., Rowbotham, T. J., Saunders, N. A., Embley, T. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+amplification+and+sequencing+of+the+16S+ribosomal+DNA+of+an+intracellular+Legionella+species+recovered+by+amoebal+enrichment+from+the+sputum+of+a+patient+with+pneumonia.">Direct amplification and sequencing of the 16S ribosomal DNA of an intracellular Legionella species recovered by amoebal enrichment from the sputum of a patient with pneumonia.</a> FEMS Microbiol. Lett. 67, 165-168 (1991).</li><li>Rowbotham, T. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+of+Legionella+pneumophila+serogroup+1+from+human+feces+with+use+of+amebic+cocultures.">Isolation of Legionella pneumophila serogroup 1 from human feces with use of amebic cocultures.</a> Clin. Infect. Dis. 26, 502-503 (1998).</li><li>Greub, G., La Scola, B., Raoult, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Amoebae-resisting+bacteria+isolated+from+human+nasal+swabs+by+amoebal+coculture.">Amoebae-resisting bacteria isolated from human nasal swabs by amoebal coculture.</a> Emerging Infect. Dis. 10, 470-477 (2004).</li><li>Isenberg, H. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Clinical microbiology procedures handbook. , (1992).</li><li>Gimenez, D. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Staining+Rickettsiae+in+Yolk-Sac+Cultures.">Staining Rickettsiae in Yolk-Sac Cultures.</a> Stain Technol. 39, 135-140 (1964).</li><li>Thomas, V., Herrera-Rimann, K., Blanc, D. S., Greub, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biodiversity+of+amoebae+and+amoeba-resisting+bacteria+in+a+hospital+water+network.">Biodiversity of amoebae and amoeba-resisting bacteria in a hospital water network.</a> Appl. Environ. Microbiol. 72, 2428-2438 (2006).</li><li>Miyamoto, H., 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=Development+of+a+new+seminested+PCR+method+for+detection+of+Legionella+species+and+its+application+to+surveillance+of+legionellae+in+hospital+cooling+tower+water.">Development of a new seminested PCR method for detection of Legionella species and its application to surveillance of legionellae in hospital cooling tower water.</a> Appl. Environ. Microbiol. 63, 2489-2494 (1997).</li><li>Lienard, 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=Development+of+a+new+chlamydiales-specific+real-time+PCR+and+its+application+to+respiratory+clinical+samples.">Development of a new chlamydiales-specific real-time PCR and its application to respiratory clinical samples.</a> J. Clin. Microbiol. 49, 2637-2642 (2011).</li><li>Wang, Y., Ogawa, M., Fukuda, K., Miyamoto, H., Taniguchi, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+and+identification+of+mycobacteria+from+soils+at+an+illegal+dumping+site+and+landfills+in+Japan.">Isolation and identification of mycobacteria from soils at an illegal dumping site and landfills in Japan.</a> Microbiol. Immunol. 50, 513-524 (2006).</li><li>Corsaro, D., Pages, G. S., Catalan, V., Loret, J. F., Greub, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biodiversity+of+amoebae+and+amoeba-associated+bacteria+in+water+treatment+plants.">Biodiversity of amoebae and amoeba-associated bacteria in water treatment plants.</a> Int. J. Hygiene Environ. Health. 213, 158-166 (2010).</li><li>La Scola, B., 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=Legionella+drancourtii+sp.+nov.,+a+strictly+intracellular+amoebal+pathogen.">Legionella drancourtii sp. nov., a strictly intracellular amoebal pathogen.</a> Int. J. Syst. Evol. Microbiol. 54, 699-703 (2004).</li><li>Thomas, V., Casson, N., Greub, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+Afipia+and+Bosea+strains+isolated+from+various+water+sources+by+amoebal+co-culture.">New Afipia and Bosea strains isolated from various water sources by amoebal co-culture.</a> Syst. Appl. Microbiol. 30, 572-579 (2007).</li><li>La Scola, B., 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=Amoeba-resisting+bacteria+and+ventilator-associated+pneumonia.">Amoeba-resisting bacteria and ventilator-associated pneumonia.</a> Emerging Infect. Dis. 9, 815-821 (2003).</li><li>Collingro, 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=Recovery+of+an+environmental+Chlamydia+strain+from+activated+sludge+by+co-cultivation+with+Acanthamoeba+sp.">Recovery of an environmental Chlamydia strain from activated sludge by co-cultivation with Acanthamoeba sp.</a> Microbiology. 151, 301-309 (2005).</li><li>Lienard, J., Croxatto, A., Prod'hom, G., Greub, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Estrella+lausannensis,+a+new+star+in+the+Chlamydiales+order.">Estrella lausannensis, a new star in the Chlamydiales order.</a> Microbes Infect. 13, 1232-1241 (2011).</li><li>La Scola, B., 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=A+giant+virus+in+amoebae.">A giant virus in amoebae.</a> Science. 299, 2033 (2003).</li><li>Boyer, M., 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=Giant+Marseillevirus+highlights+the+role+of+amoebae+as+a+melting+pot+in+emergence+of+chimeric+microorganisms.">Giant Marseillevirus highlights the role of amoebae as a melting pot in emergence of chimeric microorganisms.</a> Proc. Natl. Acad. Sci. U.S.A. 106, 21848-21853 (2009).</li><li>Thomas, V., 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=Lausannevirus,+a+giant+amoebal+virus+encoding+histone+doublets.">Lausannevirus, a giant amoebal virus encoding histone doublets.</a> Environ. Microbiol. 13, 1454-1466 (2011).</li><li>Raoult, D., Renesto, P., Brouqui, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laboratory+infection+of+a+technician+by+mimivirus.">Laboratory infection of a technician by mimivirus.</a> Ann. Internal Med. 144, 702-703 (2006).</li><li>Greub, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Parachlamydia+acanthamoebae,+an+emerging+agent+of+pneumonia.">Parachlamydia acanthamoebae, an emerging agent of pneumonia.</a> Clin. Microbiol. Infect. 15, 18-28 (2009).</li><li>Lamoth, F., Greub, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Amoebal+pathogens+as+emerging+causal+agents+of+pneumonia.">Amoebal pathogens as emerging causal agents of pneumonia.</a> FEMS Microbiol. Rev. 34, 260-280 (2010).</li><li>Lienard, J. G., Ashbolt, K., Sen, N. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ch.+6.">Ch. 6.</a> Environmental microbiology, current technology and water applications. , 143-162 (2011).</li><li>Boughalmi, M., 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=High-throughput+isolation+of+giant+viruses+of+the+Mimiviridae+and+Marseilleviridae+families+in+the+Tunisian+environment.">High-throughput isolation of giant viruses of the Mimiviridae and Marseilleviridae families in the Tunisian environment.</a> Environ. Microbiol. , (2012).</li><li>Ovrutsky, A. R., 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=Cooccurrence+of+Free-Living+Amoebae+and+Nontuberculous+Mycobacteria+in+Hospital+Water+Networks,+and+Preferential+Growth+of+Mycobacterium+avium+in+Acanthamoeba+lenticulata.">Cooccurrence of Free-Living Amoebae and Nontuberculous Mycobacteria in Hospital Water Networks, and Preferential Growth of Mycobacterium avium in Acanthamoeba lenticulata.</a> Appl. Environ. Microbiol. 79, 3185-3192 (2013).</li></ol>

Amoebal coculture and amoebal enrichment are efficient methods that allowed the isolation of many new bacterial and amoebal species. Results obtained with these methods confirm the ubiquitous presence of both amoebae and amoeba-resisting bacteria in the environment, and most interestingly in manmade water networks that are considered to be controlled by chemical treatments such as chlorination and ozonation. Amoebal coculture and amoebal enrichment are essential tools to isolate and cultivate these potentially pathogenic...

Before the advent of molecular diagnosis, microorganisms present in environmental niches or in clinical samples were often detected by cultivating them on different selective media, mainly on agar in Petri dishes. The phenotype of the bacterial colonies and their metabolic activity then allowed bacterial classification at species level. Broth may also be used to increase the sensitivity of detection. However, both techniques do not allow the recovery of bacteria that grow slowly or not at all on these media. This is the reason why molecular approaches are so widely used nowadays. Nevertheless, detection of DNA provides no clue on the viability of the bacteria. Moreover, contrarily to culture, molecular approaches do not result in a strain that can be further characterized.
Studying pathogens that grow poorly on solid media or that need cells to grow is complicated. Most of these &#34;difficult to grow&#34; bacteria are fastidious intracellular bacteria, often discovered and characterized following large outbreaks as it was the case for Legionella pneumophila. This bacterium was characterized following an outbreak that occurred during an American Legion convention. As many as 182 persons were infected and 29 died due to a severe pneumonia1,2. It was later demonstrated that amoebae were the natural hosts of this bacterium and that their presence in the hotel air-conditioning system and water networks was at the origin of the outbreak of the so-called Legionnaire&#39;s disease3.
Amoebae are present worldwide and were isolated from soil, air, water and the nasal mucosa of human volunteers (reviewed in 4). These &#34;free-living&#34; amoebae are generally dividing autonomously in the environment but may occasionally invade permissive hosts5. Amoebae feed on various microorganisms through phagocytosis and subsequent lysosomal digestion by hydrolases6. Many facultative or obligate intracellular bacteria are able to resist digestion and thus infect and divide in amoebae as for example Legionella, Chlamydia-related bacteria or mycobacteria (reviewed in 7 and 8). Free-living amoebae likely represent an important potential reservoir for intracellular bacteria that have yet not been discovered. This led our group to implement in Lausanne two main techniques, called amoebal coculture and amoebal enrichment, which allowed different groups to isolate several new obligate intracellular microorganisms from various environmental samples9-15.
Since amoebae are professional phagocytes grazing on bacteria, a bacterium able to resist phagocytosis and to grow inside these protists might also colonize human phagocytes and be pathogenic towards humans. This was partially demonstrated for some Chlamydia-related bacteria, such as Waddlia chondrophila. W. chondrophila can grow not only in amoebae but also in several cell types such as mammalian epithelial cells, macrophages, and fish cell lines16-18. The amoebal coculture also appears relevant for detecting intracellular bacteria in clinical samples19,20, including stools which are heavily contaminated with different bacterial species21.
Here we describe the major steps of amoebal coculture and amoebal enrichment, including (a) treatment of environmental or clinical samples; (b) the growth of amoebae on axenic media and on a bacterial lawn of Escherichia coli and (c) the selection and characterization of intracellular bacteria.

<table border="1">
	<tbody>
		<tr>
			<td>Name of Reagent/ Equipment</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments/Description</td>
		</tr>
		<tr>
			<td>Glucose monohydrate</td>
			<td>Merck, Darmstadt, Germany</td>
			<td>108342</td>
			<td></td>
		</tr>
		<tr>
			<td>0.22 &#956;m pore size membrane</td>
			<td>Merck Millipore, Darmstadt, Germany</td>
			<td>SCVPU11RE</td>
			<td></td>
		</tr>
		<tr>
			<td>proteose peptone</td>
			<td>Becton-Dickinson, Franklin Lakes, NJ</td>
			<td>211693</td>
			<td></td>
		</tr>
		<tr>
			<td>yeast extract</td>
			<td>Becton-Dickinson, Franklin Lakes, NJ</td>
			<td>212750</td>
			<td></td>
		</tr>
		<tr>
			<td>Cell culture flasks</td>
			<td>Becton-Dickinson, Franklin Lakes, NJ</td>
			<td>353135</td>
			<td></td>
		</tr>
		<tr>
			<td>Kova slide</td>
			<td>Hycor, Indianapolis, IN</td>
			<td>87144</td>
			<td></td>
		</tr>
		<tr>
			<td>cell culture microplates</td>
			<td>Corning Inc, Corning, NY</td>
			<td>3524</td>
			<td></td>
		</tr>
		<tr>
			<td>Diff-Quik staining kit</td>
			<td>Siemens Healthcare diagn., Munich, Germany</td>
			<td>130832</td>
			<td></td>
		</tr>
		<tr>
			<td>Ziehl fuchsin</td>
			<td>Fluka, St-Louis, MI</td>
			<td>21820</td>
			<td></td>
		</tr>
		<tr>
			<td>basic fuchsin</td>
			<td>Sigma, St-Louis, MI</td>
			<td>857843</td>
			<td></td>
		</tr>
		<tr>
			<td>Phenol</td>
			<td>Sigma, St-Louis, MI</td>
			<td>P1037</td>
			<td>Corrosive and mutagenic</td>
		</tr>
		<tr>
			<td>malachite green oxalate</td>
			<td>Fluka, St-Louis, MI</td>
			<td>63160</td>
			<td></td>
		</tr>
		<tr>
			<td>Paraformaldehyde 16% solution</td>
			<td>Electron Microscopy Sciences, Hatfield, PA</td>
			<td>15710</td>
			<td></td>
		</tr>
		<tr>
			<td>Saponin</td>
			<td>Sigma, St-Louis, MI</td>
			<td>84510</td>
			<td></td>
		</tr>
	</tbody>
</table>

discovery of new intracellular pathogens by amoebal coculture and amoebal enrichment approaches

Intracellular pathogens such as legionella, mycobacteria and Chlamydia-like organisms are difficult to isolate because they often grow poorly or not at all on selective media that are usually used to cultivate bacteria. For this reason, many of these pathogens were discovered only recently or following important outbreaks. These pathogens are often associated with amoebae, which serve as host-cell and allow the survival and growth of the bacteria. We intend here to provide a demonstration of two techniques that allow isolation and characterization of intracellular pathogens present in clinical or environmental samples: the amoebal coculture and the amoebal enrichment. Amoebal coculture allows recovery of intracellular bacteria by inoculating the investigated sample onto an amoebal lawn that can be infected and lysed by the intracellular bacteria present in the sample. Amoebal enrichment allows recovery of amoebae present in a clinical or environmental sample. This can lead to discovery of new amoebal species but also of new intracellular bacteria growing specifically in these amoebae. Together, these two techniques help to discover new intracellular bacteria able to grow in amoebae. Because of their ability to infect amoebae and resist phagocytosis, these intracellular bacteria might also escape phagocytosis by macrophages and thus, be pathogenic for higher eukaryotes.

Using amoebal coculture and amoebal enrichment, a whole range of environmental and/or pathogenic bacteria were discovered (Table 1).
Amoebal coculture was used by our group and others to analyze environmental samples, water treatment plants and water distribution systems. A broad range of microorganisms could be isolated with this technique. The most common bacteria isolated by amoebal coculture are members of the Mycobacterium genus that could be recovered from water...

Watch this Scientific Journal Video about Discovery of New Intracellular Pathogens by Amoebal Coculture and Amoebal Enrichment Approaches at JoVE.com

Discovery of New Intracellular Pathogens by Amoebal Coculture and Amoebal Enrichment Approaches

Amoebal coculture is a cell culture system using adherent amoebae to selectively grow intracellular pathogens able to resist phagocytic cells such as amoebae and macrophages. It thus represents a key tool to discover new infectious agents. Amoebal enrichment allows discovery of new amoebal species and of their specific intracellular bacteria.

Intracellular pathogens such as legionella, mycobacteria and Chlamydia-like organisms are difficult to isolate because they often grow poorly or not at ...

Research

JoVE Journal

Immunology and Infection

Infection of Zebrafish Embryos with Intracellular Bacterial Pathogens

Zebrafish (Danio rerio) embryos are increasingly used as a model for studying the function of the vertebrate innate immune system in host-pathogen ...

Single Cell Measurements of Vacuolar Rupture Caused by Intracellular Pathogens

Shigella flexneri are pathogenic bacteria that invade host cells entering into an endocytic vacuole. Subsequently, the rupture of this membrane-enclosed ...

Monitoring Changes in Membrane Polarity, Membrane Integrity, and Intracellular Ion Concentrations in Streptococcus pneumoniae Using Fluorescent Dyes

Monitoring Changes in Membrane Polarity, Membrane Integrity, and Intracellular Ion Concentrations in Streptococcus pneumoniae Using Fluorescent Dyes

Membrane depolarization and ion fluxes are events that have been studied extensively in biological systems due to their ability to profoundly impact ...

Rapid Analysis of Chromosome Aberrations in Mouse B Lymphocytes by PNA-FISH

Defective DNA repair leads to increased genomic instability, which is the root cause of mutations that lead to tumorigenesis. Analysis of the frequency ...

Biolistic Transformation of a Fluorescent Tagged Gene into the Opportunistic Fungal Pathogen Cryptococcus neoformans

Biolistic Transformation of a Fluorescent Tagged Gene into the Opportunistic Fungal Pathogen Cryptococcus neoformans

The basidiomycete Cryptococcus neoformans, an invasive opportunistic pathogen of the central nervous system, is the most frequent cause of fungal ...

Identification of Rare Bacterial Pathogens by 16S rRNA Gene Sequencing and MALDI-TOF MS

There are a number of rare and, therefore, insufficiently described bacterial pathogens which are reported to cause severe infections especially in ...

High-throughput Detection of Respiratory Pathogens in Animal Specimens by Nanoscale PCR

Nanoliter scale real-time PCR uses spatial multiplexing to allow multiple assays to be run in parallel on a single plate without the typical drawbacks of ...

Visualizing Intracellular SNARE Trafficking by Fluorescence Lifetime Imaging Microscopy

Soluble N-ethylmaleimide sensitive fusion protein (NSF) attachment protein receptor (SNARE) proteins are key for membrane trafficking, as they catalyze ...

Zika Virus Specific Diagnostic Epitope Discovery

High-density peptide microarrays allow screening of more than six thousand peptides on a single standard microscopy slide. This method can be applied for ...

Human Colonoid Monolayers to Study Interactions Between Pathogens, Commensals, and Host Intestinal Epithelium

Human 3-dimensional (3D) enteroid or colonoid cultures derived from crypt base stem cells are currently the most advanced ex vivo model of the intestinal ...