Microbiology Flashcards
What is microbiology?
Microbiology is the study of all living organisms that are too small to be visible to the naked eye.
Who is the father of microbiology?
Antonie van Leeuwenhoek
What are the four major groups of Human Pathogens, and what are they?
-Protozoa: Single-celled animals.
-Fungi: Higher plant-like organisms.
-Bacteria: Generally small, single-celled.
-Viruses: Very small obligate parasites, non-living.
Which Human pathogens are eukaryotes and prokaryotes?
- Eukaryotes: Protozoa and Fungi.
-Prokaryotes: Bacteria.
What are the 8 eukaryotes’ characteristics?
- Size 5-50 µms
- Complex (Compartmental)
- Frequently multi-cellular
- Linear chromosome + Histones
- Introns/Exons
- 80S Ribosomes
- No/Flexible Cell Wall (sterols)
- Cell cycle (mitosis/meiosis
What are the 9 prokaryotes’ characteristics?
- Size 0.5-10 µms
- Simple (relatively)
- Often single-celled
- Single Circular Chromosome
- Gene structure (introns rare)
- 70S Ribosomes
Co-transcription/translation - Rigid Cell Walls (PG)
- Rapid Cell cycle
What are the 10 characteristics of eukaryotic’s cell structure?
- Cell membrane
- Nucleus
- Centriole/Centrosome
- Nucleolus/Ribosomes
- Endoplasmic Reticulum (ER)
- Cytosol
- Mitochondria
- Golgi
- Cytoskeleton
- Secretory Vesicles, Lysosomes
What are the 10 characteristics of a prokaryotic’s cell structure?
- Plasma Membrane
- Cell Wall (Peptidoglycan)
- Nucleoid (DNA & associated proteins)
- Ribosomes
- Cytoplasm
- Capsule, Flagellar, Pili
Draw both Eukaryotic cells and Prokaryotic cells’ cell structure.
Check it.
What is the structure of the cytoplasmic membrane and its function?
Lipid bilayer which acts as a selective membrane. It retains the cytoplasm and transports molecules between the extracellular and intracellular environments.
What are bacteria sensitive to?
Disruption of the plasma membrane by physical or chemical methods.
What is a nucleoid?
The nucleoid is a chromatin-dense area within the cytoplasm and contains the bacterial DNA, associated proteins and RNA that are responsible for controlling the bacteria’s activity and reproduction
What is the Prokaryotic Protein Synthesis like? (6 steps)
- Gene (DNA)- Undergoes transcription
- mRNA (DNA-dependent RNA polymerase)
- Ribosome (tRNA) - Undergoes translation
- Protein
- 2nd, 3rd, 4th Structure
- Export/Assembly/Processing
What is the Peptidoglycan Cell Wall?
The peptidoglycan (murein) sacculus is a unique and essential structural element in the cell wall of most bacteria.
What is the structure of the Peptidoglycan Cell Wall like?
- There are continuous sugar chains: NAM-NAG
- To connect those chains, peptide side bridges are built by five amino acids.
What are the cell walls of Gram +ve like, and what is it a target of?
- Rigid layer
- Barrier
- Repeated Polysaccharide
structure - Gram +ve
- Multi-layer & often secondary
polymer - Target of Penicillin
What are the cell walls of Gram -ve like, and what is it a target of?
- Rigid layer
- Barrier
- Repeated Polysaccharide
structure - Gram–ve
- Outer membrane
- Often decorated with LPS
- Periplasmic space
- Target of Penicillin
What are lipopolysaccharides?
The primary function of LPS is to provide structural integrity and a permeability barrier to protect the bacterial cell from entering deleterious molecules such as toxins and bile salts during its inhabitation in the gastrointestinal tract.
What organisms (Gram-ve or Gram+ve) have Flagella & Fimbriae
Both
What are flagella?
Flagellum, plural flagella, hairlike structure that acts primarily as an organelle of locomotion in the cells of many living organisms.
What are fimbriae?
Fimbriae are long filamentous polymeric protein structures located at the surface of bacterial cells. They enable the bacteria to bind to specific receptor structures and colonize specific surfaces.
Draw the flagellar motor
From bottom to top:
-Series of rings
-Inner membrane
-Rod
-Peptidoglycan
-Outer membrane
-Hook
-Filament
What can flagella and fimbriae be for?
Adherence, sex and motility
What five things do prokaryotic cells need for growth?
- Food
- Temperature
- Hydrogen Ion Conc
- Osmotic protection
- Oxygen
What foods are required for Prokaryotic Growth?
-C source organic, e.g. proteins/sugars
inorganic, e.g. fix CO2
-O & H
-N source, eg. Amino acid Ammonia
-Inorganic salts P, S, K, Mg, Ca, Fe
-Trace Elements Zn, Cu, Mn, Ni, Mo,
-Vitamins (small organic cofactors)
e.g. Biotin Folic Acid, Niacin
What temperatures are required for Prokaryotic Growth? Depending on the three organisms?
- Psychrophiles (low temp)
- Thermophiles (high temp)
- Mesophiles (body temp)
What is the human commensals’ pH?
6.8-7.2
Regarding osmotic protection, what are the human commensals?
0.85% NaCl
What five prokaryotes need oxygen for growth?
Aerobes
Micro-aerophiles
Facultative anaerobes
Obligate Anaerobes
Capnophilic
Draw the Bacterial growth curve
- Lag Phase
- Exponential Phase
- Stationary Phase
- Decline Phase
What are the four classifications of Microorganisms?
- Appearance
(Shape; Size; Arrangement; Cell Wall; i.e. Gram-positive/Gram-negative) - Growth Requirements
(Aerobic/Anaerobic (e.g., strict anaerobes)
Requirement for Blood products (e.g. serum proteins)
Sensitivity to agents (e.g. NaCl, Bile, K tellurite)) - Enzyme/metabolic tests
(Coagulase test, Catalase test.
Hemolysis (Streptococci ONLY),
Biochemical profiling (e.g. carbohydrates metabolized)) - Molecular tests
(Immunological tests, e.g., cell surface antigens
DNA sequencing, e.g., qPCR or 16sRNA
Protein profiling e.g., Mass-spec analysis)
How are prokaryotic pathogens identified?
Direct observation under the microscope from a sample or cultured colony, usually fixed & stained.
What are the five shapes of bacteria?
- Cocci
- Bacilli
- Vibrio
- Spirilla
- Spirochaetes
Division in one plane for cocci produces…
Chains of 4-20 cocci. E.g. Streptococcus
Division in three planes for cocci produces…
Clumps. E.g., Staphylococcus
What are the two divisions of Bacillus/Bacilli?
-Rod-shaped bacteria
-Chains of bacilli
Where are chains of bacilli more common?
More common with Gram +ve bacilli
What is fusiform?
Long slender rods & species include emerging pathogens in the GI tract, mouth, head & neck.
Slightly curved rod: Gram+ve human pathogen, true or false?
FAAAAAAAAAAALSE.
Slightly curved rod: Gm –ve human pathogens
What are the two kinds of Spiral-shaped bacteria?
- Rigid spiral bacterium
- Flexible spiral bacterium
Example of Rigid spiral bacterium
Spirillum
3 Examples of Flexible spiral bacterium
Spirochaetes
Treponema & Borrelia
What are spores?
A spore is a cell produced by certain fungi, plants (moss, ferns), and bacteria. Spores are involved in reproduction. Certain bacteria make spores as a way to defend themselves. Spores have thick walls. They can resist high temperatures, humidity, and other environmental conditions.
What are toxins?
It is a poisonous substance that is a specific product of the metabolic activities of a living organism and is usually very unstable, notably toxic when introduced into the tissues, and typically capable of inducing antibody formation.
What do Gram+ stains like?
Crystal violet/iodine complex
What do Gram- stains like?
Pink
What are the limitations of Gram stain?
Not all organisms stain well with Gram stain
What two organisms do not stain well with Gram stain?
- Mycobacterium tuberculosis
- the organism that causes TB
- has a lipid-rich/waxy cell wall that does not take up the stain
- Treponema pallidum
- a spirochaete organism that causes syphilis, a sexually transmitted infection/disease
Meaning of aerobic
The organism grows in oxygen/air
Meaning of Obligate Aerobes
Require oxygen (in the laboratory)
Meaning of Obligate Anaerobes
Tolerate oxygen
Meaning of Capnophillic
Prefer high CO2 levels.
Microaerophillic low oxygen levels required.
What are the two selective media for the growth of specific prokaryotes?
- Mannitol Salt Agar (MSS)
-7.5% Salt allows preferential isolation of Staphylococci
-Mannitol fermentation produces acid & turns agar/colony yellow - Salmonella-Shigella (SS)
-bile salts inhibit coliforms
Why is selective media important?
Because the presence of specific substances permits the growth of one organism over another.
What is differential media?
The incorporation of chemicals produces visible changes in colonies that facilitate
identification (differentiation)
What are the two differential media?
- MacConkay Agar
- bile salts & crystal violet
- Lactose only C source & neutral red indicates fermentation.
- facilitate identification of Enterobacteriaceae.
-Eosin & Methylene Blue (EMB) - lactose salts & two dyes
- allows identification of lactose fermenters, e.g., E.coli
What are the three colony characteristics?
- Form
- Elevatiom
- Margin
What are the 6 characteristics in form?
- Punctiform
- Circular
- Filamentous
- Irregular
- Rhizoid
- Spindle
What are the five characteristics of elevation?
- Flat
- Raised
- Convex
- Pulvinate
- Umbonate
What are the 6 characteristics of margin?
- Entire
- Undulate
- Lobate
- Erose
- Filamentous
- Curled
What are the three categories of the identification of Streptococcus spp?
Alpha (partial), Beta (complete) & Gamma (no hemolysis)
What are the Lancefield Groupings?
A, B, C, F, G
Lancefield grouping is a system of classification that classifies catalase-negative Gram-positive cocci based on the carbohydrate composition of bacterial antigens found on their cell walls.
What do you do after Lancefield Grouping?
You add the size:
- Pyogenic (Large)
- S. milleri (Small)
What 2 branches does the biochemical characterization divide?
- Metabolic Profiling
* Utilisation of Carbon sources; (acid production)
* Utilisation of amino acids; - Exo-Enzyme production
* Catalase (2H2O2 to 2H2O & O2)
* Coagulase (clot plasma)
S. aureus + ve
* Hydrolysis of Lipid Clostridia species
* Urease (Urea converted to ammonia & CO2)
How do you carry out the identification
- Inoculate/Resuspend a Single colony
- Transfer 100 µls into automated biochemical profiling.
What are serological tests for?
This section analyses blood samples for the presence of viral antigens and antibodies (IgG and IgM) to help diagnose diseases and check immune status.
What is the process of identification in serological tests? (6 steps)
- Host immune response to the antigen by raising antibodies.
- Check if the antibody is specific to microbe/virus (Polyclonal) or single component (monoclonal)
- Detect presence of specific IgM antibody to virus/microbe
- Demonstrate IN VITRO by agglutination reaction
- It has a rapid detection of viruses (24 hours)
- It can identify specific serotypes of bacteria.
What is the key concept in serology?
Antibody/Antigen interaction
What is the detection of viruses in serological tests like?
It is rapid, within 24 hours.
How can it be possible to identify the stage of infection?
Using two different tests.
What is agglutination, and why is it important?
This is the immune process where antibodies bind to multiple pathogens forming clumps. Enhancing phagocytosis and preventing the pathogens from infecting other host cells.
What is genome sequencing, and what is its function?
Scientists use a process called genomic sequencing to decipher the genetic material found in an organism or virus. Sequences from specimens can be compared to help scientists track the spread of a virus, how it is changing, and how those changes may affect public health.
What are the other three pieces of DNA technology and their definitions?
-qPCR: qPCR stands for quantitative polymerase chain reaction and is a technology used for measuring DNA using PCR.
-Next-generation sequencing: It’s a massively parallel sequencing technology that offers ultra-high throughput, scalability, and speed. The technology determines the order of nucleotides in entire genomes or targeted regions of DNA or RNA.
-Nanopore sequencing: is a unique, scalable technology that enables direct, real-time analysis of long DNA or RNA fragments. It works by monitoring changes to an electrical current as nucleic acids are passed through a protein nanopore. The resulting signal is decoded to provide the specific DNA or RNA sequence.
What can successful amplification of DNA
target indicate?
The presence of an organism or even specific
virulence factor
What is 16sRNA?
The 16S rRNA gene encodes the small subunit ribosomal RNA molecules of ribosomes, responsible for the essential process of converting genetic messages to functional cell components via the translation of mRNA to proteins.
What is MALDI-TOF?
Matrix-assisted laser desorption/ionization time of flight.
Mass spectrometry (MS) has become a widely used technique for rapidly and accurately identifying bacteria, mycobacteria, and specific fungal pathogens in the clinical microbiology laboratory.
What are the four good characteristics of MALDI-TOF?
- Powerful- 99% correct
- Rapid- Colony tested in 6 minutes
- Precise- Species, sub-species, sometimes strain level
- Cost-effective- 17-32% cost of conventional techniques
What organisms are MALDI-TOF not so good with?
Streptococci and staphylococci
Draw the classification of GRAM NEGATIVE organisms.
Check-in notion
Draw the classification of GRAM POSITIVE organisms.
Check-in notion
What are the seven characteristics of the Linnaean Classification?
- Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Subtilis
Define microbiome
A microbiome is a community of micro-organisms living together in a particular habitat.
Define pathogenesis and the seven steps of the pathogen’s life.
Pathogenesis is the process where a pathogen is formed.
1. Transmission/spread
2. Reservoir of Pathogens
3. Contact (Exit/entry)
4. Pathogens Adhere/Colonize & Invade the host.
5. They evade host defenses
6. Multiply/Complete its life cycle
7. Exit the host– Which is now damaged
Define pathogen
A harmful organism that produces a pathology
Define Mutualism
This refers to interactions between two organisms in which both organisms benefit.
Define commensalism
This refers to interactions between two organisms where one benefits and the other is unaffected.
Define symbiosis
Interaction between two different organisms living in close physical association, typically to the advantage of both.
Define opportunistic pathogen and name an example
An organism that causes infection when an opportunity/change in natural immunity arises
* e.g., in an immunocompromised individual
Define contaminant
An organism that is growing in a culture by accident
Define virulence
The capacity of a microbe to cause damage to the host
How is virulence often determined?
In one model system e.g Mouse Respiratory Model
Name two fungal infections and define what they are
- Candida spp
-Yeast, from skin infection to Candidaemia - Aspergillus spp
-Moulds, infections in immunocompromised.
10 Gram-negative common infectious bacteria in the UK
5 Gram-positive common infectious bacteria in the UK
- Streptococcus spp.
- Staphylococcus spp.
- Enterococcus spp.
- Clostridium
- Fusobacterium spp
What do the gram-negative cocci appear like on Gram film?
Appears in pairs- Termed diplococci
There are 10 species of gram-negative cocci, and two are pathogenic. Which are they?
- Neisseria Meningitis
- Neisseria Gonorrhoeae
What is the commonest cause of bacterial meningitis?
Neisseria meningitis
What does Neisseria Gonorrhoeae cause?
It causes gonorrhea, a sexually transmitted disease.
What is immunization like for meningitis? How many vaccines are there?
Meningitis B vaccine
6-in-1 vaccine
Pneumococcal vaccine
Hib/Men C vaccine
MMR vaccine
Meningitis ACWY vaccine
What is the most common cause of bacteremia?
E.coli
What are the Coliforms?
‘Coliform’; is a term used to describe species of
Gram-negative bacilli that look like Escherichia
coli (E. coli) on Gram film and when cultured on
blood agar
How does coliform grow best?
Grow best aerobically but can also grow
anaerobically
Are coliforms part of normal bowel flora?
Yessss
How can coliforms differentiate from each other? (3)
- Biochemical reactions
- Antigenic structure of cell wall (serotyping)
- O antigens (cell wall) and H antigen (flagella)
What three infections can coliforms cause?
- Any coliform entering a normally sterile site can cause serious infection.
- Urinary tract infection
- Peritonitis
- Biliary tract infection
What is the first line antibiotic used for coliform infections?
Gentamicin
Define sepsis
Sepsis is a syndrome defined as life-threatening organ dysfunction due to a dysregulated host response to infection.
What happens to patients with coliform sepsis and why?
Patients with coliform (Gram-negative) sepsis become very unwell very quickly because of the
endotoxin released from the Gram-negative cell wall when the bacteria die.
What are the 4 things that happen during sepsis?
Small blood vessels become “leaky” and lose fluid
into the tissues
* Lower blood volume requires the heart to work harder
to maintain oxygenation of tissues (↑HR)
* Poor tissue oxygen perfusion means blood supply to
less essential organs (skin, kidneys, liver are shut
down to try to maintain the blood supply to the brain
* Blood clotting system is activated, causing blood
clotting in tiny blood vessels→ uses up all clotting
factors→ increased risk of hemorrhage.
What are the seven steps of fever production?
- Antigen (a component of micro-organisms
or endotoxin interact with macrophages (WBC) - Macrophages release cytokines into the bloodstream
- Cytokines travel to the anterior hypothalamus (brain)
- Cytokines also stimulate the adverse effects of
sepsis - Prostaglandin E is released, which increases
the body’s thermal set point - Prostaglandin E is released, which increases
the body’s thermal set point - Fever is produced, and it increases survival from infection
Why is fever beneficial in fighting infection?
It prevents the proliferation of bacteria.
What may happen to young children with fever?
febrile convulsions
What are four common Gram-positive pathogens, and what do they cause?
- Streptococcus
Pneumonia, GAS, Oral Streps, - Enterococcus
Enteric infections - Staphylococcus
Nosocomial & Community
Skin infections & biofilms - Clostridia (Clostridioides)
Anaerobic bacilli
What does Nosocomial mean?
(of a disease) originating in a hospital.
Which is the most significant Pathogenic Streptococci?
Group A Streptococcus
What are five Group A Streptococcus-associated diseases?
- Streptococcus pyogenes
- B-haemolytic
- Streptococcal sore throat (Scarlet fever)
- Invasive diseases e.g necrotizing fasciitis.
- Puerperal sepsis (infection of pregnant & post-natal women)
How many cases are there of Group A Streptococcus
700 million cases worldwide
What is pneumonia?
Acute inflammation of the lungs is often caused by inhaled pneumococci of
the species Streptococcus pneumonia. The alveoli and bronchioles of the lung
become plugged with a fibrous exudate.
What happens to 1 million children with pneumonia each year?
Those <5 years old die.
What is Streptococcus pneumonia also known as?
Pneumococcus
What kind of cocci is Streptococcus pneumonia?
Gram-positive alpha-haemolytic cocci
What is Streptococcus pneumonia part of?
Part of normal upper respiratory tract flora in many people
What is the commonest cause of pneumonia and can also cause severe forms of meningitis?
Streptococcus pneumonia.
How many capsular types are there, and how many can you be immunized against?
90+ different capsular types – vaccine available that immunizes against the commonest
23 types
What medication are the majority of UK strains sensitive to?
Penicillin
What are the essential group in The non-hemolytic Streptococci and its two divisions?
The most important group is the Enterococci
* Enterococcus faecalis
* Enterococcus faecium
The non-hemolytic Streptococci is part of what flora and is it pathogenic?
Part of normal bowel flora.
Not particularly pathogenic but can cause problems if they get into a normally
sterile site,
What is the common cause of urinary tract infection?
The non-hemolytic Streptococci
Most strains of E. faecalis are sensitive to ____ but not to ______
- Amoxicillin
- Penicillin
What can some very antibiotic-resistant strains of E. faecium cause hospitals?
“VRE” (vancomycin-resistant
enterococci) can cause “outbreaks” of infections in hospital
What are three Staphylococci organisms, and can you identify them?
- S. aureus (Coagulase +ve)
- S. epidermidis (Coagulase -ve)
- S. saprophiticus
What are the commonest cause of skin, soft tissue, and wound infection?
S. aureus
What is the commonest cause of bone and joint infection?
S. aureus
When does S.aureus multiply?
Multiplies at the site of acquisition,
causing local infection &
inflammation e,g abscesses
Where can it cause abscesses?
Spleen, liver and kidneys.
Where can you get S. aureus infections?
Nosocomial & community
What is MRSA?
MRSA is a type of bacteria resistant to several widely used antibiotics.
Where can it be picked up, S.aureus, and who is more likely to get it?
- Mainly nosocomial, in intensive care units.
Elderly and immunocompromised; burns patients, surgical patients, those with IV lines, and dialysis patients.
What kind of organism is Clostridioides?
Gram-positive anaerobic bacilli
What is it a part of, and where is it found?
Part of normal bowel flora of man and animals – found in feces and soil.
Clostridioides are unable to produce spores. True or False?
FALSE.
Produces spores that can survive outside the body for many months.
What exotoxins can Clostridioides release that cause severe tissue damage? (What would be the symptoms?)
- Clostridioides difficile – causes antibiotic-associated diarrhoea, esp. in the elderly
- Clostridium perfringens – causes “gas” gangerene, a severe soft tissue infection following
contamination of a wound - Clostridium tetani – causes tetanus, a usually fatal paralytic illness
What exotoxins can Clostridioides release that cause severe tissue damage? (What would be the symptoms?)
- Clostridioides difficile – causes antibiotic-associated diarrhea, esp. in the elderly
- Clostridium perfringens – causes “gas” gangrene, a severe soft tissue infection following
contamination of a wound - Clostridium tetani – causes tetanus, a usually fatal paralytic illness
What are antibiotics?
A drug used to treat or prevent infection caused by microorganisms.
Define Bacteriostatic
Inhibit the growth of bacteria
Define bacteriocidal
Kills bacteria
What medication has a narrow spectrum?
Penicillin narrow spectrum active against Gram-positive bacteria
What medication has a broad spectrum?
Tetracycline is active against many Gram-positive & Gram-negatives
What are the six characteristics of an ideal antibiotic?
- Selective toxicity/minimal toxicity to host
- Cidal
- Long half-life (Low binding to plasma proteins)
- Appropriate tissue distribution
- No adverse drug interactions/side effects
- Oral & parenteral preparations
What are the six common antibiotic targets?
- Cell wall– Peptidoglycan synthesis
- Ribosomes– Protein synthesis
- DNA replication– Nucleic Acid Synthesis
- DNA gyrases
- Metabolic Pathways
- Cell Membrane Function
What are pharmacodynamics?
The branch of pharmacology is concerned with the effects of drugs and the mechanism of their action.
What is pharmacokinetics?
The branch of pharmacology concerned with the movement of drugs within the body.
What are the three pharmacodynamics elements?
- MIC/MBC
Minimum inhibitory/bactericidal Conc
in vitro - Time Dependent Action
in vitro
in vivo blood concentrations - Spectrum (broad to narrow)
in vitro
Gram-positive only
Gram-negative
Anaerobic bacteria
What are the three pharmacokinetics elements?
- Absorption
Peritoneal versus IV
Acid sensitivity - Distribution
Plasma Binding proteins
GI/Urinary tract
Environment permissive for activity - Elimination
Liver
Kidney
What are β-Lactam antibiotics?
β-Lactam antibiotics are bactericidal agents that interrupt bacterial cell-wall formation as a result of covalent binding to essential penicillin-binding proteins (PBPs)
What are the three cell wall targeting antimicrobials, and which are β-Lactam antibiotics?
- Penicillins (β-Lactam antibiotics)
- Cephalosporins (β-Lactam antibiotics)
- Glycopeptides (Not β-Lactam antibiotics)
What do non-β-Lactam antibiotics do?
They stop bacteria’s life-sustaining chemical reactions (called metabolic pathways) by inhibiting bacterial enzymes.
What are the seven penicillins?
- Penicillin, flucloxacillin, amoxicillin, temocillin, co-amoxiclav & piperacillin/tazobactam
What are piperacillin/tazobactam?
Combination injection.
Name the one cephalosporin and why it is good.
Ceftriaxone
* Wider spectrum & more resistant to b-lactamases
Name the two glycopeptides
Vancomycin, teicoplanin
What does lysis involve?
Lysis involves uncoupling the cell wall synthesis from remodeling enzymes (lytic enzymes)
Is penicillin safe?
Yes, very few side effects, and safe in pregnancy.
How is penicillin excreted?
Via kidneys, rapidly
What is so good about penicillin?
Variety, very flexible molecule with side groups & chains able to alter multiple features
What is the range of penicillin’s spectrum
Range from narrow spectrum to broad spectrum
i.e., empiric prescribing & can act on a wide range of bacteria, usually both Gram-negative
& Gram-positive organisms, but also some can be quite specific
What are the three limitations of penicillin?
- Patients can be “hypersensitive” (“allergic”)
Allergy to one penicillin means allergy to all penicillins (& sometimes also to the
cephalosporins) - Rapid excretion via the kidneys.
Results in frequent dosing (usually 3-6 times daily) are necessary. - Resistance;
The long history of clinical use, many microbes exposed to these compounds & some resistant
strains have been selected.
What are the three principal compounds of penicillin?
- Benzylpenicillin
-Penicillin G, Intravenous IV - Phenoxymethyl penicillin
- Penicillin V, oral
- Benzathine penicillin
- long-acting, Intramuscular IM
What is penicillin V’s spectrum? Mention the 8 examples of organisms.
Narrow largely Gram +ve Spectrum.
-Streptococci, Staphylococci, Clostridia, Neisseria, Treponema, Listeria, Bacillus,
Corynebacterium
How is the Penicillin V absorbed?
Through the intestine
What is Penicillin sensitive to and when does it need to be consumed?
Sensitive to stomach acid (30 min before a meal, 3 hours after)
What is Penicillin V’s peak plasma concentration?
30-60 minutes after taking
What is the percentage of Penicillin V that binds to plasma proteins?
75-90%
For how long are the serum levels maintained? (In Penicillin V)
30-60 minutes
What is the meaning of serum blood levels?
The amount of a given medication present in your blood at the time of testing
Is Amoxicillin safe? How is it best absorbed?
Safe, well-tolerated antibiotic.
Well-absorbed when given orally but can also be given intravenously.
Draw a Beta-lactam ring
Square- HN
O with a double bond
When is the effectiveness of amoxicillin challenged?
The spread of b-lactamases, as they have enzymes that destroy the b-lactam ring
What is the spectrum of amoxicillin like? What are the eight organisms it can fight?
- Spectrum extended from Gram +ve into Gram-ve
- Enterococci, Moraxella, Listeria, Escherichia, Proteus, Haemophilus, Salmonella &
Shigella
How is amoxicillin absorbed?
Through intestine
Amoxicillin is unstable in the presence of stomach acid, true or false?
False, stable in the presence of stomach acid.
What is the peak plasma concentration after taking amoxicillin?
60-120 minutes
What is the percentage of amoxicillin that binds to plasma proteins?
20%
What is its plasma half-life? (Amoxicillin)
60 minutes
What is Co-amoxiclav made out of?
Amoxicillin and clavulanic acid
1
1
1
1
1
1
