It depends on the reason you want germ-free mice to begin with. Just like someone who's loved and lost love is not the same as someone who has never loved at all, a host who has had a microflora and lost components of the microflora (via antibiotics or whatever) is not the same as a host who has never had the microflora to begin with. Some bacterial flora prime the immune system during development, and these effects can be permanent or transient. However, if you are simply trying to decrease the microbial load to mitigate the effects of radiation or some other inflammatory stimulus, or to deplete the endogenous microflora to enhance growth of a new bacterial species (which is essentially what happens in patients who get C. difficile colitis), then antibiotics are certainly used.

The issue is you have a pseudo germ free animal not a totally germ free animal. There is most likely supression of the bacteria not elimination. May depend on the antibiotics and protocol. Also the anitbiotics themselves may change gut function and metabolism in general. The model is useful but you need to consider the side effects. There are several papers published with such a model eg Chromatogr B Analyt Technol Biomed Life Sci. 2012 Mar 1;887-888:8-18.

Thank you for the feedback.

The lungs of animals are essentially 'germ' free. However the gut has tremendous numbers of microorganisms and it is almost impossible to wipe out all those.

If by gem-free you mean free of human pathogens, it is possible to decrease the microbial load with antibiotics but this will alter the gut flora and raising the possibility of increasing yeasts in the gut as well as the potential for developing antibiotic resistant organisms.

Gnotobiotic organisms are essentially different from normal animals and their immune functions are very different.

I know gnotobiotics are expensive but it may the only way to go if you truly want germ-free animas.

I'd like to recommend You the best specialist in field of germ-free animals - prof.Gennady Podoprigora.

e-mail [email protected]

Hi Jeffrey,

We did a depletion of gut bacteria in MyD88−/− mice few years ago.

In conventional C57BL/6 MyD88−/− mice, the microbiota was eliminated as described in [21]. Briefly, mice were provided ampicilin (1 g/L, Sigma), vancomycin (500 mg/L, Sigma), neomycin sulphate (1 g/L, Sigma) and metronidazole (1 g/L, Sigma) in drinking water for three weeks prior to colonization with the E. coli MG1655 strain. Animal experiments were carried out in accordance with the European guidelines for the care and use of laboratory animals.

21.Cell. 2004 Jul 23;118(2):229-41.Recognition of commensal microflora by toll-like receptors is required for intestinal homeostasis. Rakoff-Nahoum S, Paglino J, Eslami-Varzaneh F, Edberg S, Medzhitov R.

http://www.ncbi.nlm.nih.gov/pubmed?cmd=Search&doptcmdl=Citation&defaultField=Title%20Word&term=Recognition%20of%20commensal%20microflora%20by%20toll-like%20receptors%20is%20required%20for%20intestinal%20homeostasis.

answer part2

The mice were housed in isolator and manipulated as we do for germfree mice (with sterile cage bedding food and water, that were changed frequently during the treatment) . The decontamination protocol was adapted from the link i send just before.

It works to decontaminate mice, you have to keep them in gremfree environment.

However as such mice had been in contact with bacteria and have been through all the physiological adaptations induced by life in a germfull environment.

The paper with the decontaminated MyD88-/- mice is the following:

M. De Paepe, V. Gaboriau-Routhiau, D. Rainteau, S. Rakotobe, F. Taddei, N. Cerf-Bensussan. Trade-off between bile resistance and nutritional competence drives Escherichia coli diversification in the mouse gut. PLoS Genet., 7 (2011), p. e1002107

http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.1002107

I suppose what you mean by 'relatively' is important. As others have said, you can certainly repress the microbes (nearly all of them anyway), but you will almost certianly have a rebound of some sort after the antibiotic treatment ends.

It depends on the reason you want germ-free mice to begin with. Just like someone who's loved and lost love is not the same as someone who has never loved at all, a host who has had a microflora and lost components of the microflora (via antibiotics or whatever) is not the same as a host who has never had the microflora to begin with. Some bacterial flora prime the immune system during development, and these effects can be permanent or transient. However, if you are simply trying to decrease the microbial load to mitigate the effects of radiation or some other inflammatory stimulus, or to deplete the endogenous microflora to enhance growth of a new bacterial species (which is essentially what happens in patients who get C. difficile colitis), then antibiotics are certainly used.

Thank you for the additional feedback. All of you present very important points to consider.

It is not recommended. Firstly, it is not easy to remove 100% of micribiota including fungi, virus, bacteria etc by using couples of antibiotics. Secondly, sometimes this alteration is reversible as a result of microbiota transmission from other sites of body to gastrointestinal and lung system (for examle we know the bridge of bacterial diversity between nasal and skin microbiota).

I agree with the answer of Cyrus Toorkey of Burlington County College

Unfortunately not. You can get reduction up to 99.9% but not 100%. The only way ist to do cesarean section at birth and keep the pups in a sterile environment.

@Jane C Deng. How to differentiate the role of gut microbes Vs lung microbes by using antibiotic treatment. As antibiotic treatment would also effect the lung microbes, So how one can be sure that the observed effect is due to depletion of gut microbes or lung microbes?

Hi,

try this paper:

 Pham LN, 2008. Methods for generating and colonizing gnotobiotic zebrafish. Nat. Protoc. 3:1862–1875.

Hopefully, it can help you, 

O.A.