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Summary of all the lectures of pharmaceutical microbiology
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Pharmaceutical microbiologyLecture 1 Introduction
03/02/2020 Visser
Microbial contamination of pharmaceutical preparations may cause:
- Health hazard to the patient
- Altered therapeutic activity of the product
- Decrease in quality
Not all microorganisms are hazardous.
Chemical, physical and microbiological stability in compounds determine the stability.
Microorganisms need an environment that is comfortable to them (food, temperature). There are
extrinsic (temperature) and intrinsic factors (product composition and physico-chemical properties).
The combination of intrinsic and extrinsic factors will determine the types and number of
microorganisms that will develop in a product or on a surface.
Two types of microorganisms: the ones that use oxygen for growth and the ones that can live
without it (aerobic/anaerobic).
Longer ago most people died of influenza, nowadays not anymore. Heart diseases and cancers now
are the main causes of death. This change is because of increased hygiene, development of
antibiotics and we live longer (cancer and heart diseases develop at a later age).
There are microorganisms which are very helpful to us. Most microorganisms are not harmful.
With microscopes you can visualize microorganisms. Robert Hook described the first
microorganisms. Antoni van Leeuwenhoek discovered the first bacteria. This was done with a light
microscope. In a light microscope the sample is illuminated with visible light. Magnification is the
capacity of a microscope to enlarge an image. The limiting factor in seeing small objects however is
not magnification but resolution. Resolution is the ability to distinguish two adjacent objects as
distinct and separate. Light microscopes have some limitations so there also are some other
microscopes.
To study living organisms you need to use a phase contrast microscope. In other microscopes you
have to stain the bacteria, causing them to die.
Examples of microscopes are: light, phase contrast, fluorescence, electron, bright-field, dark-field and
differential interference contrast microscope.
Louis Pasteur proved that there was no spontaneous generation of microorganisms. Using the
zwanenhals, microorganisms were not able to enter the flask and contaminate (liquid kept sterile).
But when you let the liquid comes in contact with the contamination you could see growth.
Robert Koch proved that some microorganisms can cause harm. Colonies were found in a diseased
animals and injected in the healthy animal. If you transfer a microorganism to another animal (from
the same species) it will cause the same disease.
LUCA = last universal common ancestor; all three domains have this ancestor. Bacteria, archaea and
eukaryotes. All these domains have connections with each other some genes are in common.
There also are differences in the genes and in the cell wall.
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,Archaea live under extreme conditions. They are not pathogenic.
Bacteria and eukaryotes (including plants, yeasts and fungi) are the majority of the pathogenic and
spoilage organisms.
Prokaryotic cells: very simple cells. They have few internal structures. The genetic material is at
random in the cell no nucleus. They lack organelles.
Eukaryotic cells: membrane enclosed, DNA containing nucleus. Organelles are present.
Not every microorganism has a cell wall. Under influence of antibiotics you interfere with the cell
wall, so if you want to treat a microorganism without a cell wall you cannot use antibiotics.
Common factor of all cells:
- Cytoplasmic membrane forming a permeability barrier to separate the inside from the
outside.
- Protein synthesis by ribosomes
- DNA genome. In prokaryotes the genome is located in closed circular chromosomes. In
eukaryotes the genome is in linear molecules within the nucleus.
All cells show some form of metabolism (cell growth, cell division) and evolution. Some cells show
differentiation, communication, genetic exchange or motility.
Bacteria form spores under extreme conditions as a defence mechanism. This is also a problem when
you want to sterilize preparations. You need to treat under harsh conditions and high temperature in
order to sterilize them.
Bacteria are 0.2 to 10 um. They lack a nucleus and have a prokaryotic cell structure. They can adapt
themselves to a large variety of environments (aerobic/anaerobic) and have the capacity to grow
extremely fast (E. coli can divide every 20 seconds). Bacteria have different morphologies/different
forms such as coccus, filamentous, rod, spirillum, spirochete and budding and appendaged. Some
bacteria can change shape during division. Their shape has something to do with osmotic pressure.
Human bacterial infections are caused by strict pathogenic species and opportunistic pathogens. In
some cases you only need a few of certain microorganisms to get sick but in other cases you need a
lot. Depending on the type and amount of microorganism you can develop certain diseases.
Bacterial endospores are highly differentiated cells that are extremely resistant to heat, harsh
chemicals and radiation. They enable the organisms to endure unfavourable growth conditions.
Mollicutes or mycoplasmas smallest free-living prokaryotic organisms. They are widespread in
nature. They lack a cell wall so if antibiotics act on the cell wall they will not affect these
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, microorganisms. One of the dangerous mycoplasmas is one that causes infections in the upper
respiratory tract.
Fungi (molds, mushrooms, yeasts) have different ways of growing; most of them grow on surfaces.
Some fungi are pathogenic to humans or produce toxic substances. they can cause contamination
and spoilage. Molds are aerobic and grow on the surface or in the uppermost layers of a substrate.
Yeasts are typically unicellular and undergo budding.
Viruses are 20 to 300 nm. They are not able to divide by themselves and lack independent
metabolism; they require a host. They have a core of genetic material which is in the form of DNA or
RNA. Viruses often are dangerous and difficult to treat. Most common one is the influenza, but also
AIDS, SARS, Ebola and corona.
Prions are very dangerous and cause neurodegenerative disorders. Prion infections can cause gekke
koeien ziekte/Creutzfeldt-Jacob disease. You develop holes in your brain which will cause several
symptoms. At the moment you have these symptoms it is most of the time fatal. Prions cannot
replicate well.
You do not want viruses and prions in your preparations.
Usually a filter is used to remove the microorganisms from pharmaceutical preparations. There will
always be a few present. The limits are described in the pharmacopoeia.
Microbial contamination can be a direct hazard to the patient. Whether an infections or disease is
triggered depends on the number of microorganisms, the ability of the contaminant to grow,
properties of the strain, route of administration and the immunocompetence of the patient.
We have natural barriers to defend ourselves from illness by microorganisms, such as the skin and
mucosa. There will be some competition between external microorganisms and the ones that you
already have on your skin. Also ciliated epithelium, stomach, enzymes in the GI tract, microbiota and
the immune system form barriers against contamination.
In the stomach the pH is very low, resulting in not much microorganisms being able to survive.
You also have to look at the presence of oxygen. When microorganisms need oxygen they cannot live
in anaerobic places (mouth, intestines, skin, genitals, biofilms). The skin, nose, mouth and lungs are
aerobic.
Contamination can be primary of secondary. Primary contamination occurs at the premises or during
preparation. Secondary contamination occurs during storage, transport or administration of the
product.
You can prevent contamination by working sterile. You can also mitigate the risk by wearing
dedicated gowning, hygiene, controlling the environment, cleaning and disinfection, qualified
employees, etc.
Microorganisms are able to release very toxic products. These toxins can cause fever.
Lecture 2 Cell wall
04/02/2020 Visser
Not all cells have a cell wall. The most essential structures of a cell are the cytoplasmic membrane
and the cell wall. The cell wall gives structural strength to the cell so that it does not burst due to
osmotic pressure.
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