Comments on: Bacteria in phase contrast

By: Oliver

Oliver — Fri, 20 May 2011 12:12:41 +0000

Sorry to disappoint you, but the type of investigations that you want to do are not possible with a microscope. The shape of bacteria can only be used in very rare cases for identification purposes. How do you want to identify Clostridium difficile in a mix of thousands of different kinds of bacteria? Concerning biological danger: yes. You are working with unknown bacteria of human origin, which are (potentially) pathogenic. This belongs to an elevated security level. Medical diagnostics is based on biochemical reactions or the analysis of DNA, but not microscopy. There are some cases when microscopes can be used, but this requires culturing the bacteria. Generally the bacteria do have to be cultured and then isolated. This takes time, experience and extensive laboratory equipment. The cultured bacteria are then chemically analyzed. If you take a stool sample and culture the bacteria on agar plates, then you will receive thousands of different kinds of bacterial colonies. Which one is C. difficile? You would have to analyze each one of them. There is also another problem: Clostridia are anaerobic, this means that they do not grow in presence of oxygen. You need a special incubation chamber, in which there is no air.

In short: I would not do any form of self-diagnosis, simply because it does not work. If you want to go into microscopy because of a hobby (and not for medical reasons), then I have to say that there are far more interesting things to observe than bacteria. Have a look at plain yogurt to observe bacteria. The maximum useful magnification of a light microscope is about 1000x, everything above this is empty magnification.

If you want to study the demographics ob bacteria (which bacteria occur where), then you would be better off doing a PCR study….. And as a matter of fact, this is indeed done. Simply because different bacteria have the same shape under the microscope does not mean that they are related, so the microscopic appearance is often pretty meaningless.

I know that this is kind of ironic. In the past, the microscope contributed greatly for understanding the microbial world, but nowadays the microscope only plays a minor role when doing bacteriological work.

Greetings, Oliver.

By: Haresh Patel

Haresh Patel — Sun, 15 May 2011 17:45:04 +0000

I want to find what kind of bacteria are present in my stools and in particular, observe the presence of C-diff bacteria but also study the demographics of the bacteria as much as possible. I am considering buying a 1000x-2000x compound microscope with phase contrast optics. I need some guidance about how to prepare the specimen and is there in biological danger in doing this. I am a retired electronics engineer.
I hope the bacteria do not have to be cultured because I do not understand the process and may not be practical for home use. Can anybody help?

By: Oliver Kim

Oliver Kim — Wed, 25 Aug 2010 18:27:03 +0000

Thanks for the feedback. I teach both middle and high school Biology.

By: charlie guevara,fingerlakes/NY

charlie guevara,fingerlakes/NY — Thu, 24 Jun 2010 21:03:46 +0000

Thanks for you enthusiastic web microscopy resource…sweet!!

I don’t know what level biology you teach, but your students must be lucky to engage your lecture/lab efforts.

Somewhere I once read that thanks to inter-net/online resources and technologies..’ a science of everything’ is really approaching educators/researchers/pupils/life-time learners. By contrast with my childhood nature/science/home hobbies/microscopy path to ‘life-time learning’…your interactive web site has everything but ‘the masses of real-time pupils and visitors talking to one another…your website is a self-contained first stop for a young student microscopist!

BRAVO…charlie guevar,fingerlakes/US