gram positive bacteria

Finish Your Antibiotics

I’m sorry, this isn’t Jojo at all but I think I’ve had it for today. As a pharmacy tech, I’m tired of hearing “Well, I started to feel better so I didn’t finish them.” I always knew this but now as a Molecular and Cellular Biology major, I not only know why but how. If you’re willing to heed my advice from the title, good; be on your way. If you need to know more, keep reading.

It’s widely known–to some extent–that not completing a regiment of antibiotics can result in resistant bacteria, or even super bacteria.

But in an infection, you already have resistant bacteria lurking. Not taking antibiotics doesn’t literally create resistant bacteria. So how, then, do the antibiotics take care of the resistant ones?

A lot of antibiotics aren’t bacterialcidal: They don’t actually kill them. Many inhibit growth by some mechanism depending if the bacteria is gram negative or gram positive. For example, penicillin inhibits growth by disrupting the formation of a peptidoglycan layer on gram positive bacteria. Others target the LPS layer on gram negative ones. This keeps the non resistant bacteria at bay. So what kills the resistant ones? Your immune system. Antibiotics buy time and energy for your immune system to recognize and destroy the resistant strains. Your immune system is intelligent in that sense and can form antibodies for new illnesses. It’s important to give your immune system this time because bacteria grow, mutate, and transfer genetic material at astonishing rates. If you wanted to look at a microcosm of the mechanics that go into evolution, you’ve got it with bacteria. 

There are three methods aside from binary fission in which they transfer genes (I won’t get into the minutia of the form of informational material): Transformation, transduction and conjugation.

In transformation, a bacteria can pickup lost genes from a ruptured and dead cell.

Transduction is a way to transfer information via a viral vector.

In conjugation, genes are transferred through something called a pilus: It’s a bridge between two cells that pipes a copy of the information from one cell to another receptive cell and is the only method that doesn’t involve killing either cells. Resistant bacteria like to give around that resistance information like they’re burning a CD for their friends.

So please finish your antibiotics if you’ve been given them. It doesn’t matter if you’ve started to feel better or even great. Finish them.

(Hey science people, If I’ve missed anything or even got something wrong, help me out. There’s obviously lengthy stuff I’ve left out but I think I got the basics).


Penicillin is a widely used antibiotic prescribed to treat staphylococci and streptococci bacterial infections. 

  • beta-lactam family 
  • Gram-positive bacteria = thick cell walls containing high levels of peptidoglycan
  • gram-negative bacteria = thinner cell walls with low levels of peptidoglycan and surrounded by a lipopolysaccharide (LPS) layer that prevents antibiotic entry 
  • penicillin is most effective against gram-positive bacteria where DD-transpeptidase activity is highest.

Examples of penicillins include:

  • amoxicillin
  • ampicillin
  • bacampicillin
  • oxacillin
  • penicillin


  • Penicillin inhibits the bacterial enzyme transpeptidase, responsible for catalysing the final peptidoglycan crosslinking stage of bacterial cell wall synthesis.
  • Cells wall is weakened and cells swell as water enters and then burst (lysis)
  • Becomes permanently covalently bonded to the enzymes’s active site (irreversible)

Alternative theory: penicillin mimics D-Ala D-Ala

Or may act as an umbrella inhibitor


  • production of beta-lactamase - destroys the beta-lactam ring of penicillin and makes it ineffective (eg Staphylococcus aureus - most are now resistant)
  • In response, synthetic penicillin that is resistant to beta-lactamase is in use including egdicloxacillin, oxacillin, nafcillin, and methicillin. 
  • Some is resistant to methicillin - methicillin-resistant Staphylococcus aureus (MRSA).  
  • Demonstrating blanket resistance to all beta-lactam antibiotics -extremely serious health risk.

anonymous asked:

Hola mi amor~can you pls explain the translation to Jimin's Serendipity on this part, "You're my penicilium (blue mold)" I think I'm missing something because it doesn't sound romantic to me at all lol but the music video is so lovely~

hyee ;DD 

so 넌 내 푸른 곰팡이 can be literally translated to ‘you are my blue mould’

넌 you are
내 my
푸른 bluish/of azure 
곰팡이 mould

but 푸른 곰팡이 is also the korean word for a type of fungus called ‘penicillium’ ^^ now there are many type of species of penicillium, some are pathogens, and some are of great economical values, the greatest being those species that can produce ‘penicillin’, a group of antibacterial substances that has powerful effect in destructing or inhibitng growth of common bacteria that infect men, its what we use today to make antibiotics. scientists considered the discovery of penicillin a miracle because it changes the diagnostic distribution for psychiatric patients back in the 1940s since it has therapeutic effect

alexander flemming, the scientist who made the discovery called it a ‘serendipitous’ discovery because it wasn’t his original intention, his research was on staphylococcus, gram positive bacteria that at that time, had caused bacterial infections amonsgts men that could have been fatal. long story short he came to his lab one mornign (his lab is known often for being untidy and stuff, which is a big no no) and found one of his plates containing bacterial culture which he was working on, was contaminated with fungus, he thought it was weird because for some reasons, the bacterial infected area was ‘cleared’ meaning the fungus or sth that the fungus produced destroyed those bacteria.

he didn’t plan on making the discovery but his accidental chance upon this miraculous organism had lead to world’s first antibiotic, a start of many, many other discoveries, revolutionizing all medicine <3

so really when jimin says ‘넌 내 푸른 곰팡이’ he means ‘you’re like the blue night sky that blankets my world, the one who protects me, my angel, you’re my world. the universe moved its axis to make us aligned, and nothing not even the slightest was out of place. our happiness was meant to be, cos you love me and i love you.’

in a way, jimin is asking us to be happy too, cos if anything, our existence itself is happiness. we are a serendipity, and i think that’s really soft

Types of Pathogenic Microorganisms

The average human body contains about 10 trillion cells. Imagine how much that is! If our population was 1400 times greater in the entire world, then we still would not be more than the number of cells in the entire body. Amazing isn’t it? 

But what if I tell you the gut alone, contains 100 trillion microorganisms living within it this very minute? And hence the picture above, our world is really a microorganism’s world, we are simply the ones large enough to be seen. 

And thus we see the importance of microbiology, how exactly are these microorganisms affecting our lives? 

Most of these microorganisms are actually beneficial to our body, for example, by aiding in the process of digestion, however, there are microorganisms that are damaging to their host, either by the production of toxic products, or direct infection, and these microorganisms are termed pathogenic. 

To have an idea of this, let us talk about the types of microorganisms, and the pathogenic ones in each type, that is, the one that can give us a disease. 

Microbes that Cause Diseases

Microbes that cause diseases can be divided into 5 groups of organisms:

  1. Bacteria
  2. Fungi
  3. Protozoa
  4. Helminths and Rotifiers
  5. Viruses

There is also a recently discovered type of microbe that can cause a disease, known as a prion. 

Of these microbes, we can classify them in several different ways. 

Classification of Microbes:

Firstly, it is important to consider the status of prions and viruses. Technically, these “microbes” are not living. Prions are simply misfolded proteins, and viruses are only “alive” when they infect an organism. Thus, both prions and viruses have their own classifications. 

As for the other organisms, we can classify them in several ways:

  • Eukaryote vs Prokaryote
    • In this classification scheme, all bacteria are prokaryotes, and fungi, protozoa, helminths and rotifers are eukaryotes. 
      • The prokaryotes are further subdivided into eubacteria and archaebacteria. Eubacteria are the medically important bacteria, while archaebacteria are a group of evolutionarily distinct bacteria. 

Differences between Eukaryotes and Prokaryotes:

  • General Size
    • Eukaryotes are much larger than Prokaryotes, being about 10-100mm in diameter. 
    • Prokaryotes are much smaller, being about only 0.2-2mm in diameter. 
  • Nucleus vs Nucleoid: 
    • Eukaryotic cells contain a true nucleus, with multiple chromosomes, linear DNA, and a nuclear membrane, using mitotic apparatus to ensure chromosomes are equally distributed to the daughter cells. 
    • Prokaryotic cells contain a nucleoid, which is an area of loosely organized, circular supercondensed DNA, lacking nuclear membrane and mitotic apparatus.

Keep reading

Bacterial Taxonomy 1 - Classification Based on Morphology and the Gram Stain. 

Taxonomy, is literally the science of classification. Look at the picture above, and imagine that all those little divisions, like “firmicutes” are different phyla under the kingdom of bacteria. Then those phyla are further subdivided into different classes, then orders, then families, then genera, and then finally species! Take a look at how this works for one particular bacteria, called streptococcus mutans. 

Wow, there’s a lot to classify, probably why it’s taxonomy: it’s such a taxing job.

Ahem, right, so. As you’ve probably noticed, Streptococcus mutans is named using its Genera and its Species name. Similarly, all organisms have a scientific name comprising of two parts: The genus, followed by the species. It is very important to classify organisms in this way because: 

  1. It establishes criteria for identifying organisms. 
  2. Allows arrangement of related organisms into groups. 
  3. Provides important information on how organisms evolved.  

Bacteria are classified, usually, according to their morphological, metabolic and biochemical differences, although genetic and immunologic factors are also now being considered. 

One of the earliest, and most fundamental methods of classifying bacteria depended on the use of the Gram Stain. 

Gram Stain

Unlike large organisms like humans, parrots and dra-, erm, Komodo Dragons, which are easy to spot and have a distinct appearance to the eye, bacteria are colourless and invisible to light microscopy. Thus, gram staining had to be developed to give bacteria a colour, and visualize them. Since bacteria would either respond to the stain, or not, all bacteria were subsequently classified into gram-positive and gram-negative bacteria. 

There are 4 steps to the Gram Stain Procedure. 

  1. Pour crystal violet stain (a blue dye) and wait for 60 seconds. 
  2. Wash off with water and flood with iodine solution. Wait for 60 seconds. 
  3. Wash off with water and then “decolourize” with 95% alcohol solution. 
  4. Counter-stain with safranin (a red dye). Wait 30 seconds and then wash off with water. 

Basically, when viewed under the microscope, cells that absorb the crystal violet dye and hold on to it become blue: These are gram-positive. Alternatively, if the crystal violet is washed off by the 95% alcohol, the cells absorb the safranin and appear red. These are gram-negative. 

Gram Positive = Blue 

Imagine yourself sitting by the beach, opposite crystal blue waters, or kayaking across deep waters, or even river tubing across the bluest of rivers.. won’t you say yes to that? So, Blue = Positive. Note that Gram-Positive bacteria may also appear purple if the red safranin is not effectively washed off. This is because blue + red is purple. 

Gram Negative = Red

Now you’re sitting in sweltering red heat, sweat pouring down your body, the sun red in the sky. You don’t want that, do you? Or for comic book fans, you can picture Superman’s face when he sees a Red Sun in the sky. NOPE, thinks Superman. So Red = Negative. 

This difference occurs due to a difference in morphology of the bacteria. 

Gram Positive vs Gram Negative Bacteria 

Unlike eukaryotic animal cells which contain only one cell membrane composed of phospholipid separating the nucleus from the ECF, both gram-positive and gram negative bacteria contain more than 1 layer: the layer outside the bacterial cytoplasmic membrane is the peptidoglycan layer. 

Keep reading

I understand Infectious Agents is a super important class. Heck, most of the problems in vet med are probably caused by some pathogen or another. However…. holy cow there’s so much information. 

Like for this exam we’ve got about 30 species of bacteria, their virulence factors, what diseases and symptoms they cause, layman’s names, vaccines, spores, growth requirements, motility, diagnosis, hosts, and more.

And this is only gram positive bacteria.

And I don’t think we’ve finished gram positives.

This exam tomorrow is not gonna be great.

New Antibiotic That Fights Resistant Bacteria Found

by Michael Keller

Scientists combing through soil have found a potential new class of antibiotics that appear to stop infections from drug-resistant microbes, an international team announced today.

The work, though still early in its development, is a bit of good news during a time when global health authorities warn about the dangers of more microbial species developing resistance to drugs. The World Health Organization, for instance, has sounded the alarm about a “post-antibiotic era, in which common infections and minor injuries, which have been treatable for decades, can once again kill.”

Discovery of the drug, now being called teixobactin, came after screening 10,000 compounds produced by soil-dwelling bacteria that had never been cultured. In a study published in the journal Nature, the team writes that the drug works by disrupting the construction of bacterial cell walls. They were pleasantly surprised to find that the way the drug worked didn’t seem to be stopped by bacterial strains that had evolved the ability to survive antibiotic attack.

“Early on, we saw that there was no resistance development to teixobactin,” said study coauthor Kim Lewis, the director of Northeastern University’s Antimicrobial Discovery Center. “This was, of course, an unusual and intriguing feature of the compound.”

Keep reading


History Meme. 3 inventions → [2/3] Penicillin (1928)

The discovery of penicillin is attributed to Scottish scientist and Nobel laureate Alexander Fleming in 1928.[16] He showed that, if Penicillium rubens[17] were grown in the appropriate substrate, it would exude a substance with antibiotic properties, which he dubbed penicillin. This serendipitous observation began the modern era of antibiotic discovery. The development of penicillin for use as a medicine is attributed to the Australian Nobel laureate Howard Walter Florey, together with the German Nobel laureate Ernst Chain and the English biochemist Norman Heatley.

Fleming recounted that the date of his discovery of penicillin was on the morning of Friday, September 28, 1928. It was a fortuitous accident: in his laboratory in the basement of St. Mary’s Hospital in London (now part of Imperial College), Fleming noticed a Petri dish containing Staphylococcus plate culture he mistakenly left open, was contaminated by blue-green mould, which formed a visible growth. There was a halo of inhibited bacterial growth around the mould. Fleming concluded the mould released a substance that repressed the growth and lysing the bacteria. He grew a pure culture and discovered it was a Penicillium mould, now known to be Penicillium notatum. Charles Thom, an American specialist working at the U.S. Department of Agriculture, was the acknowledged expert, and Fleming referred the matter to him. Fleming coined the term “penicillin” to describe the filtrate of a broth culture of the Penicillium mould. Even in these early stages, penicillin was found to be most effective against Gram-positive bacteria, and ineffective against Gram-negative organisms and fungi. He expressed initial optimism that penicillin would be a useful disinfectant, being highly potent with minimal toxicity compared to antiseptics of the day, and noted its laboratory value in the isolation of Bacillus influenzae (now Haemophilus influenzae). After further experiments, Fleming was convinced penicillin could not last long enough in the human body to kill pathogenic bacteria, and stopped studying it after 1931. He restarted clinical trials in 1934, and continued to try to get someone to purify it until 1940.[read more]

Txch This Week: Building A Better Future

by Michael Keller

For the last three days, we all have been forced to absorb the tragic news coming out of France. The attack on cartoon journalists and police in Paris has hit hard everyone who holds liberty and the freedoms of speech and of the press dear.

It has reminded us of the terrible, irrational things that people are capable of doing to each other. It also made us here at Txchnologist thankful to be spending our days bringing our readers news from the other side of the spectrum. In times of darkness, it helps to be reminded that light is flickering every minute of every day around the world. Artists, writers, musicians, inventors, healthcare providers, scientists and others are at work right now in every country saving lives, expressing themselves or in some meaningful way striving to better the human condition.

Here is just a brief recap of the scientists and engineers working to make the world a better place that we reported on this week. There are many, many more who we couldn’t get to—on every continent and from the spectrum of cultural, religious and political backgrounds. We hope it reminds you of the good in the world and helps fortify your faith in humanity.

Keep reading