Microbiology Test, and Antimicrobial Resistance… (Day 43)

Microbiology antimicrobials zone of inhibition

My day of Microbiology, and my first ever Microbiology test, I am slightly nervous as every professor has their own way of doing tests and so far it’s been pretty different in each case. We’ve been told that it is multiple choice however are not sure just what is going be in it as we have covered a ton of materials even in 5 weeks! It’s slightly daunting to think that this is just the start and they are warming us up slowly, I can now understand why people say that year 2 is the one that makes or breaks you.

Anyways after lecture we headed up to the microbiology lab, and walking in were separated around the room, and given a paper with 10 questions, 8 multiple choice and 2 short answer questions.  Here’s a couple of the questions from memory for you to try at home (you are free to ask Dr Google for help :))…

Q) Which type of microorganism is the Ziehl-Neelson staining method used for?
a) Mycobacterium
b) Brucella
c) Bacillus

Q) Describe the appearance of the R form of microorganism growth on solid agar.

Ok so feel free to free to leave your answer in a comment and I will follow up with my answers in a week or so. I managed to get 7 out of 10 correct (there were the typical MCQ trick questions) so ended up with my first C, not the best however it doesn’t count towards my final grade so with some work I am hopeful I can move it up to a B or even a A. I am definitely finding the understanding of why something works the way it does makes it so much interesting rather than just knowing that a certain test does x when y happens.

Anyways onto the practical, today was on antimicrobials and measuring their effectiveness. The most basic method of this is applying small paper discs soaked in the antimicrobial agent to a plate cultured with a bacteria and seeing if it grows around the disc or not. The bigger the area with no growth the more effective the microbial agent is, here’s my plate and I will show you the result next week.

Microbiology antimicrobials zone of inhibition
Testing different antimicrobial agents

Now Tuesday afternoon is my free time so I attempted to head to the library to get some studying in however they have some kind of book fair on and told me it was closed when I tried going in so I decided to head home and get some more Latin done.

The pretty colors of Microbiology… (Day 15)

The colorful microbiology practical

Today was pretty interesting, this mornings Microbiology lecture was on cell structure (I can see a theme for this week after Histology and Physiology yesterday also being on a similar topic. Going have to brush on my cell biology as if its getting this much attention then its gotta be pretty important! One of the things I consider most imporant within this is the difference between Gram positive and Gram negative bacteria. Most bacteria cells have a wall around them which controls the transfer of stuff in and out of the cell. This affects what types of antibiotics can be used in treatment, as to the diagnostic techniques used in the identification of it.

Anyways after this lecture it is time for a quick break and then onto the practical session, I was kinda excited to see how well I had done innoculating my plates in last weeks practical. Today we walked into a set up of loads of different coloured plates like this…

The colorful microbiology practicalSometimes I really do have to just stop and admire just how beautiful nature really is. Considering that all the bacteria on these plates can do harm to us its amazing how they manage to look so pretty.

Anyways enough of that, todays practical introduction was on the different mediums available to culture (grow) bacteria, how they are prepared and why they change the colours they do. Through my undergrad it had been a case of it just was, now I am learning the why and I am so much happier actually understanding this.

Culture media is important as when trying to determine a bacteria you basically test different properties to determine which it is. Within the selection we had today we had selective media (which restricts the type of bacteria that will grow on it), differentiative media (which tests a common property between negative and positive), and media specifically for the detection of pigment production by bacteria.

Basically agar is just a plain power that is mixed with water and then sets almost like Jelly. For selective media chemicals such as crystal violet and bile salts which restrict the growth of Gram positive bacteria (hence making it selective). For differentiative bacteria indicators are added to detect the presence of things such as pH or lactose which causes a change in color. And for special media chemicals are added to react with specific properties such as thiosulfate which is metabalised by Salmonella and forms colonies of bacteria with black centers.

Today we had prepared plates to examine the difference appearence of different bacteria on different culture media which was pretty cool. When you start to look at the differences you really do start to appreciate that a cell is alive, it eats, it puts out waste and its amazing how this happens with something so small.

Different types of microbiology agarWe then looked at the different types of growths, shapes of colonies, and then using liquid medium as well for growth in a test tube. The growth and culture of anaerobic (without oxygen) bacteria using oxidation-reduction and an anoxic jar.