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Samenvatting pharmaceutical microbiology
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PHARMACEUTICAL MICROBIOLOGYLecture 1 – Introduction
Microbial contamination of pharmaceutical preparations may cause:
• Health hazard to the patient (e.g. infection or allergic reaction)
• Altered therapeutic activity of the product.
• Decrease in quality (turbidity, loss of consistency, altered pH)
But not all microorganisms are hazardous.
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.
• Extrinsic factors – temperature
• Intrinsic factors – product composition (how much water present) and physico-
chemical characteristics
Why pharmaceutical microbiology? → research and development of anti-infective
agents (antibiotics)
Infectious diseases were the leading causes of death in 1900, whereas today they
account for relatively few deaths. This is because of the development of antibiotics.
LUCA stands for "Last Universal Common Ancestor." It is
a hypothetical organism that is believed to be the most
recent common ancestor, before the divergence of the
three domains of life: Bacteria, Archaea, and Eukarya.
Archaea contains many microorganisms which grow under extreme conditions. They
are not pathogenic. Bacteria and Eukarya are the majority of the pathogenic and
spoilage organisms.
Prokaryotic cells have a simple structure without membrane-enclosed organelles.
Prokaryotic cells do not have a nucleus. Instead, their genetic material, typically a
single, circular DNA molecule, is found in a region of the cytoplasm called the
nucleoid. The DNA is not enclosed within a membrane.
• Bacteria, archaea
Eukaryotic cells have a more complex structure with
membrane-enclosed organelles, such as mitochondria
(responsible for energy production) and chloroplasts (in
plant cells, involved in photosynthesis). They possess a
DNA containing nucleus enclosed within a nuclear
envelope.
• Eukarya (plants, animals, algae, protozoa and
fungi)
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,All cells, regardless of whether they are prokaryotic or eukaryotic, have:
• Permeability barrier (cytoplasmic membrane) - this membrane separates the
interior of the cell (cytoplasm) from the external environment.
• Ribosomes - responsible for protein synthesis.
• DNA genome - every cell contains genetic material in the form of DNA. It is the
complement of all genes in the cell.
- Prokaryotic cells: closed circular chromosomes located in a region of the
cytoplasm called the nucleoid.
- Eukaryotic cells: linear DNA molecules within the nucleus.
Some cells possess additional structures, such as a cell wall. The cell wall provides
structural strength and protection to the cell.
Properties of all microbial cells:
• Metabolism
- Cell growth, cell division
• Evolution
Properties of some microbial cells:
• Differentiation (some cells can form new cell structures such as spores)
• Communication (cells interact with each other via chemical messengers)
• Genetic exchange (exchange of DNA/genes)
• Motility (some cells are capable of self-propulsion)
Bacteria have a prokaryotic cell structure, which lacks a nucleus. They are
undifferentiated single cells and they can adapt themselves to a large variety of
environments (anaerobic/aerobic). They have the
capacity to grow extremely fast!
Bacteria have different morphologies (structures):
Human bacterial infections are caused by strict
pathogenic species (<2% of bacterial species) or by
opportunistic pathogens. Opportunistic pathogens are microorganisms that typically
do not cause disease in healthy individuals but can become pathogenic under certain
circumstances. They can cause infections in individuals with weakened immune
systems.
The amount of cells needed for an infection varies: only 10 cells of Shigella
dysentriae to provoke dysentery, but at least 1000 cells of Vibrio cholera to provoke
cholera.
Bacterial endospores are highly differentiated cells that are extremely
resistant to heat, harsh chemicals and radiation. They are survival
structures and enable the organism to endure unfavorable growth
conditions. “dormant state” of the cell.
Life cycle of an endospore-forming bacterium →
2
,Mollicutes, also known as mycoplasmas, are the smallest free-living prokaryotic
organisms. They lack a cell wall. Despite lacking a cell wall, mycoplasmas are
relatively resistant to osmotic lysis. This resistance is attributed to the presence of
sterols (such as cholesterol) in their cell membrane, which helps stabilize the
membrane structure. Mycoplasmas are widespread in nature. Many mycoplasmas
that infect humans are considered extracellular parasites, meaning they live outside
host cells and derive nutrients from their host. They can cause a range of infections,
including respiratory tract infections and genitourinary tract infections.
• Mycoplasma pneumonia (infections of the upper respiratory tract)
• Mycoplasma genitalium (nongonococcal urethritis)
Fungi (molds, mushrooms, and yeasts) typically inhabit environments such as soil
and dead plant matter. Most fungi are multicellular organisms, with the exception of
yeasts, which are typically unicellular. Fungi are responsible for contamination and
spoilage.
• Molds: obligate aerobic, grow on the surface or in the uppermost layers of a
substrate
• Yeasts: typically unicellular organisms, budding
Prions are protein-based (proteinaceous) infectious particles. The normal, cellular
form of the prion protein undergoes a misfolding process into an abnormal,
pathogenic form, which can then convert other normal prion molecules into the
abnormal form. This process leads to the accumulation of misfolded proteins in
tissues, particularly in the brain. Prions are associated with a group of
neurodegenerative disorders known as prion disorders. These disorders affect
humans and animals and are characterized by progressive neurological dysfunction
and the accumulation of abnormal prion proteins in the brain. Examples of prion
disorders include Bovine spongiform encephalopathy, commonly known as "mad
cow disease," affecting cattle. And Creutzfeldt-Jakob disease that affects humans.
Prion diseases typically have long incubation periods, ranging from months to
years. The incubation period refers to the time interval between exposure to a
pathogen and the appearance of symptoms. Prion diseases are fatal once clinical
symptoms appear.
The conversion of normal prion proteins into infectious prions happens in the brain,
thus infectious prions are generated in the brain.
Whether a microbial contaminated pharmaceutical product will trigger infection
or disease depends on:
• Number of microorganisms (colony forming units (CFU) per g or ml)
• Ability of the contaminant to grow and metabolize components of the product.
• Properties of the particular strain
• Immunocompetence of the patient, due to disease (AIDS) or use of
immunosuppressive
• Route of administration
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, Natural barriers against biological contamination:
• Skin
• Mucosa (containing lysozymes and lactoferrin)
• Ciliated epithelium
• Stomach (acidic environment, denaturation of peptides)
• Enzymes in the GI tract (microbiota)
• Immune system (quick local response)
Various parts of the human body have different oxygen environments, affecting the
types of microorganisms that thrive there. In an aerobic environment, oxygen is
present, while in an anaerobic environment, oxygen is either absent or present at
very low levels.
Aerobic environment: skin, nose, mouth, lungs
Anaerobic environment: skin (folded skin, skin creases), mouth, intestines, genitals,
biofilms.
A biofilm is a community of microorganisms that adhere to surfaces and are enclosed
within a self-produced matrix of extracellular polymeric substances.
Deterioration or spoilage of the product may result in several effects,
including:
• Loss of texture because of metabolism of oil/fat phase
• Loss of organoleptic quality because of production of olfactory products
• Loss of preservative efficacy because of metabolism of the preservative
• Loss of package integrity because of excessive gas production
• Loss of therapeutic activity because of metabolism of the active substance(s)
• Release of toxigenic substances, including toxins and pyrogens
Resident skin flora refers to the microorganisms that permanently reside on the skin's
surface or within deeper layers of the skin. These microorganisms establish stable
populations and play a role in maintaining the skin's ecosystem and preventing the
colonization of potentially harmful pathogens. Transient skin flora refers to
microorganisms that temporarily colonize the skin's surface but do not establish long-
term populations. These microorganisms are acquired from the environment or from
contact with other individuals and may persist on the skin for a short period before
being removed through activities such as hand washing.
Lecture 2 – Cell wall
The cytoplasmic membrane and cell wall are the most essential structures of a cell.
The cytoplasmic membrane separates the inside of the cell (cytoplasm) from the
outside. It is also called the gatekeeper for the entrance and exit of dissolved
substances. The cell wall confers structural strength on a cell in order to keep it from
bursting due to osmotic pressure.
The cytoplasmic membrane has a selective permeability. Nutrients go inwards,
while waste products go outwards. Proteins in the membrane facilitate the transport.
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