CSP - exam 2 - micro Flashcards
Which media/bug?_____: chocolate agar with factors V (NAD+) and X (hematin)
H. influenzaWhen you’re stuck with H. influenza, have a take-five bar and X out your troubles!
What type of media do you use to isolate Neisseria gonorrhoeae and meningitidis?
Thayer-Martin (or VPN) mediaV - vancomycin (inhibits g+ organisms)P - polymyxin (inhivits g- organisms except neisseria)N - Nystatin (inhibits fungus)To connect to neisseria, please use your VPN.
Thayer and Martin are VIP men that had messy (ness) gonorrhoeae
Pertussis media?
Bordet-Gengou (potato) agar (Bordet for Bordetella)Petussis is whooping cough. Marie had whooping cough and was from the gengou chinese tribe where they ate lots of taro (potato-like) with a bordeux wine
A bug is grown in tellunite agar, loffler medium. what bug is it?
C. Diptheriae Telle-tubby in loafers took a DIP in the C (sea)
Lowenstein-Jensen Agarwhich type of bug?
Hans jensen and lowenstein started a M.ajor TUBA duo.
Eaton agar, requries cholesterol…which bug?
M. pneumoniae
New Moms are always trying to get you to EAT more sweets and cholesterol
Pink colonies on MacConkey agar (fermentation produces acid, turning colony pink).E.coli is also grown on eosin-methylene blue (EMB) agar as colonies with green metallic sheen.which bug can be isolated on these?
lactose fermenting enterics (chris LACK’s farm is fermenting entities)with:pink monkey acid producing coloniesande.coli also grown on Esther-metal-band(in a green metallic band)lactose fermenting enterics
Charcoal yeast extract agar buffered with cysteine and ironbug?
legionellaIn a land far far away, there is a REGION, where they pledge alleigence by taking charcoal burnt bread, and sprinkling bits of iron gate from thecysteine chapel.
sabouraud agarwhich bug?
fungi!
sab is a fun guy
Which bugs don’t gram stain well?
These Microbes May Lack Real Color
Treponema (too thin to be visualized)
Mycobacteria (high lipid content in cell wall detected by carbolfuchsin in acid-fast stain)
Mycoplasma (no cell wall)
Legionelle pneumophila (primarily intracellular in REGION - silver stain)
Rickettsia (intracellular parasite LIKE A CRICKET)
Chlamydia (intracellular parasite; lacks muramic acid in cell wall)
COLORless My.boo Tre and My.pal Ricky got REGIONAL chlamydia
What stain do yo use for Chlamydia, Borrelia, Rickettsiae, Trypanosomes, and Plasmodium?
Certain bugs really try my patiences
Giemsa
Nathan Giem
Chylimbed Boulders, but Tryped some and Recked his Platsyma
What does Giemsa stain?
Chlamydia Borrelia Tyrpanosomes Rickettsiae Plasmodium
Nathan gieme climbed boulders but tripped and recked his platsyma
PAS stains what?
periodic acid-schiff
stains glycogen, mucopolysaccharides.
this is used to diagnose WHIPPLE DISEASE (tropheryma whipplei)
PAS THE SUGAR
What stain do you use to diagnose whipple disease?
PAS
periodic acid-schiff
PAS GAS
periodically, you get a whiff of acid sh** because PAS stains glycogen and mucopolysaccharides (mucho sugar and glycogen)
Ziehl-Neelsen (carbol fuchsin)
stains acid-fast organisms like mycobacteria and nocardia
Carl Nielson violin concerto is in my-back repertoire and i don’t need NO note-cards
India Ink stains what?
Cryptococcus Neoforeman
Cryptic new george foreman is actuallly indian (not black)
What stains silver?
Lori’s regional new fungi is silver
H. Pylori
Legionella
Fungi (pneumocystis)
Coxiella Burnetii is what type of bacteria
Diplobacilli: rod shaped bacteria in pairs
Streptococcus pneumoniae is what type of bacteria?
diplococci: round shaped bacteria in pairs
Stahylococcus aureus is what type of bacteria?
staphylococci – irregular clusters of round-shaped bacteria
N. haemophilis, Moraxella catarrhalis and Acinetobacter and Brucella are all gram ____
negative
Bruce had a new Humonuclous portion of acai berry that he fed to (Mory’s Cat) morttadella catarrhalis and feels negative now.
streptococcus pneumoniae and enterococcus are what kinds of bacteria?
gram posititve diplococci
___ ___: these have an absolute requirement for oxygen in order to grow.
Examples are: Pseudomonas aeruginosa (cystic fibrosis), Mycobacterium tuberculosis (Tuberculosis), Bordetella pertussis (whooping cough)
Obligate aerobes: these have an absolute requirement for oxygen in order to grow (Pseudomonas aeruginosa (cystic fibrosis), Mycobacterium tuberculosis (Tuberculosis) - Bordetella pertussis (whooping cough)
_____: requires oxygen for growth but at lower concentrations than present in the atmosphere. Example are: Campylobacter Jejuni; Helicobacter pylori)
Microaerophilic - requires oxygen for growth but at lower concentration than is present in the atmosphere; said of bacteria. (Campylobacter Jejuni; Helicobacter pylori)
Lori is at Camp Jeju Island, where the oxygen is a little lower than normal atmosphere.
____: these are capable of growth under both aerobic and anaerobic conditions.E.g. _____ group, Staphylococcus aureus etc.
Facultative: these are capable of growth under both aerobic and anaerobic conditions.E.g. Enterobacteriaceae group, Staphylococcus aureus etc.
faculty and staph entered the back of the honda rio seat
______: for example, Clostridium perfringens, which causes gas gangrene, cannot grow in the presence of oxygen
Obligate anaerobe: for example, clostridium perfringens , which causes gas gangrene, cannot grow in the presence of oxygen
UTI’s (ambulatory, uncomplicated UTIs) are caused
80% by ___
10-20% by ___
8-10% by ___
How do you determine which one is the cause?
80% by E.coli
10-20% by Staphylococcus Saprophylicus
8-10% by Klebsiella
First, you isolate it from urine.
Then find out if it is g+.
If it is g+, it cannot be E. coli because E. coli is g-.
S. saprophyticusis innately resistant to the antibiotic novobiocin
Screening coagulase-negative staphylococci from urine cultures for novobiocin resistance
is a reliable presumptive identification ofStaphylococcus saprophyticus
Which bugs do not gram stain well?
Mycobacteria (high lipid content in cell wall detected by carbofuchsin in acid-fast stain)
Treponema (too thin to be visualized)
Mycoplasma (no cell wall)
Legionella pneumophila (primarily intracellular)
Rickettsia (intracellular parasite)
Chlamydia (intracellular parasite; lacks muramic acid in cell wall)
Colorless:
My boo Trepon and My pal Ricky, had Legional Chlamydia
Legionella - silver stain
Treponemes - dark-field microscopy and fluorescent antibody staining
______ media is routinely used in clinical laboratories for enteric and respiratory tract samples. It is selective because most Gram _____ bacteria will not grow. It is also differential, because it contains lactose (C source) as well as peptides and a pH indicator. If bacteria can utilize lactose as a carbon source (very few can), they ferment the lactose, produce acid, and the pH decreases. The colonies then appear ____ because of the pH indicator. The most commonly encountered lactose positive bacteria are ____, ___, and _____. However, if they cannot ferment lactose, they use the peptides as a C source and appear the pH does not decrease so colonies appear yellow/pale white (for example, ____).
MacConkey media is routinely used in clinical laboratories for enteric and respiratory tract samples. It is selective because most Gram positive bacteria will not grow. It is also differential, because it contains lactose (C source) as well as peptides and a pH indicator. If bacteria can utilize lactose as a carbon source (very few can), they ferment the lactose, produce acid, and the pH decreases. The colonies then appear red because of the pH indicator. The most commonly encountered lactose positive bacteria are Klebsiella, Enterobacter, and Escherichia coli. However, if they cannot ferment lactose, they use the peptides as a C source and appear the pH does not decrease so colonies appear yellow/pale white (Salmonella example).
When blood agar is used as a media, what three outcomes are there?
- alpha hemolyic - green (partial hemolysis) i.e. streptocococus pneumoniae
- beta hemolytic - clear
(total hemolysis)
i.e. strepcococcus pyogene and bordatella pertussis - gamma hemolytic - no hemolysis
i.e. emterococcus
For the Gram positive cocci, _____ is catalase positive and ____ are catalase negative.
For the Gram positive cocci, Staphylococcus is catalase positive and Streptococci are catalase negative.
Coagulase test. The sample in question is usually inoculated onto plasma with latex beads coated with rabbit plasma and incubated at 37°C. A positive test is denoted by a clot formation. Most commonly used to differentiate ___ ___ (coagulase positive) from the other non-pathogenic (coagulase negative) ___ ___ (a normal flora of skin).
Coagulase test. The sample in question is usually inoculated onto plasma with latex beads coated with rabbit plasma and incubated at 37°C. A positive test is denoted by a clot formation. Most commonly used to differentiate Staphylococcus aureus (coagulase positive) from the other non-pathogenic (coagulase negative) Staphylococcus epidermidis (a normal flora of skin).
If a bacterium produces certain cytochrome c oxidases, it will turn certain indicators
dark-blue or maroon.
Strains may be either oxidase-positive (OX+) or oxidase-negative (OX-).
Oxidative positive pathogens are:
Lori painted the Monalisa original
nossofsky, mory the “vibratos” attended legional camp jeju.
If a bacterium produces certain cytochrome c oxidases, it will turn certain indicators
dark-blue or maroon.
Strains may be either oxidase-positive (OX+) or oxidase-negative (OX-).
Oxidase positive bacterial pathogens:
Pseudomonas aeruginosa, Neisseria and Moraxella, Legionella pneumophila
Helicobacter pylori, Vibrio cholerae, and campylobacter jejuni,
H. Pylori, Pseudomonas aeruginosa, neisseria, moraxella, vibrio cholerae, legionella pneumophila, campylobacter jejuni
Bacterial ___ are highly resistant, dormant structures (i.e. No
metabolic activity) formed in response to adverse environmental conditions.
survival of the organisms during adverse environmental conditions;
___ formation (____)occurswhen nutrients are depleted.
___ are highly resistance to Heat, Dehydration, Radiation and Chemicals.
Bacterial spores are highly resistant, dormant structures (i.e. No
metabolic activity) formed in response to adverse environmental conditions.
survival of the organisms during adverse environmental conditions;
Spore formation (sporulation)occurswhen nutrients are depleted.
Spores are highly resistance to Heat, Dehydration, Radiation and Chemicals.
Because of lipid rich cell wall _____ are resistant to
many disinfectants and common laboratory stains.
Once stained, the rods also cannot be decolorized with
acid solutions; hence the name ___-__bacteria.
Because of lipid rich cell wall mycobacteria are resistant to
many disinfectants and common laboratory stains.
Once stained, the rods also cannot be decolorized with
acid solutions; hence the name acid-fast bacteria.
___-___ method:Acid-fast cells will stain fuchsia.
Non-acid-fast cells will stain ___.
Ziehl-Neelsen method:Acid-fast cells will stain fuchsia.
Non-acid-fast cells will stain blue.
You isolated from Urine:
Gram positive bacteria: coagulase ____ staphylococcus is isolated
Is it Staph. Epidermidis (normal inhabitant of skin and non-pathogenic)
or Staph saprophyticus?
S. saprophyticusis innately resistant to the antibiotic _____
Screening coagulase-negative staphylococci from urine cultures for novobiocin resistance
is a reliable presumptive identification ofStaphylococcus saprophyticus
You isolated from Urine:
Gram positive bacteria: coagulase negative staphylococcus is isolated
Is it Staph. Epidermidis (normal inhabitant of skin and non-pathogenic)
or Staph saprophyticus?
S. saprophyticusis innately resistant to the antibiotic novobiocin
Screening coagulase-negative staphylococci from urine cultures for novobiocin resistance
is a reliable presumptive identification ofStaphylococcus saprophyticus
Antibiotic susceptibility
Group A and Group B streptococcus:
Bacitracin: B resistant; A sensitive
Optochin: Strep viridans is resistant; Strep. Pneumoniae is sensitive
Mnemonics: if you got a V, you are not sensitiVe
Antibiotic susceptibility
Group A and Group B streptococcus:
Bacitracin: B resistant; A sensitive
Optochin: Strep viridans is resistant; Strep. Pneumoniae is sensitive
Mnemonics: if you got a V, you are not sensitiVe
In children, pneumonia is usually caused by a ___ infection. In adults, by a ___ infection.
children - viral
adults - bacterial
Pathogens are organisms that are capable of causing disease. They can be:
- Commensal - “share from the same table”
- microorganisms that normally do no harm, and may in fact be beneficial - Transient - infrequently encountered, but may be opportunistic. Opportunistic pathogens are organisms that are capable of causing disease, only when the hosts resistance is lowered. For example, by other diseases or drugs
- Primary (overt) - capable of causing disease in healthy individuals. These are bacteria that are called obligate, meaning, if you get this bacteria, they will always cause disease.
Pathogens are organisms that are capable of causing disease. They can be:
- ____ - “share from the same table”
- microorganisms that normally do no harm, and may in fact be beneficial - ____ - infrequently encountered, but may be opportunistic. Opportunistic pathogens are organisms that are capable of causing disease, only when the hosts resistance is lowered. For example, by other diseases or drugs
- ____ (overt) - capable of causing disease in healthy individuals. These are bacteria that are called obligate, meaning, if you get this bacteria, they will always cause disease.
What are the different steps in the infection process?
EAS MEDS
Entry Adhesion Local or general SPREAD Multiplication Evasion of host defense Damage Shedding from body
The common ways that bacteria enter:
DRS. G & G
Direct inoculation (insects, opportunistic like in surgery or indwelling devices, scrapes, fomites (clothes, utensils)
Respiratory tract - streptococcus pneumoniae, bordetta pertussis
Skin - staphylococcus, streptococi
Genitourinary tract - Neisseria gonorrhea, chlamydia
GI tract - salmonella, e. coli, vibro cholerae
Once the bacteria is in your body, it needs to ADHERE.
____ - a surface structure or macro molecule that binds bacterium to a specific surface receptor.
____ - a complementary macro molecule binding site on a eukaryotic surface that binds specific adhesion
____ - filamentous proteins on the surface of bacterial cells that may behave as adhesion for specific adherence.
____ - a layer of polysaccharide on the surface of bacterial cells, which may be involved in adherence to a surface.
Once the bacteria is in your body, it needs to ADHERE.
Adhesion - a surface structure or macro molecule that binds bacterium to a specific surface receptor.
Receptor - a complementary macro molecule binding site on a eukaryotic surface that binds specific adhesion
Fimbriae (pillus) - filamentous proteins on the surface of bacterial cells that may behave as adhesion for specific adherence.
Glycocalyx - a layer of polysaccharide on the surface of bacterial cells, which may be involved in adherence to a surface.
Bacteria exhibit some specificity, or ____ during attachment. What does this mean?
Tropism.
I.E. If you injected GU type disease into your nose, you won’y get the disease, because the nasal area does not have the specific attachment type for the GU bacteria.
Examples of bacterial adhesions: LTA - \_\_\_\_ LTA - M protein complex - \_\_\_\_ Type 1 Fimbriae - \_\_\_\_ Fimbriae - \_\_\_\_ Type 1 Pilli - \_\_\_\_
LTA - Staphylococcus aureas LTA - M protein complex - Streptococcus group A Type 1 Fimbriae - E. Coli Fimbriae - Neisseria Gonorrhoeae Type 1 Pilli - Vibrio Cholerae
So why is adherence so important for disease?
Adherence to epithelial or endothelial cell linings of the bladder, intestines and blood vessels prevents washing, and subsequently allows them to colonize the tissue.
The bladder as mechanisms to effectively wash away bacteria affixed to the bladder wall. E. Coli has ___, which functions as adhesions. This ___ also functions as a sex pilli during conjugation. Most E. Coli strains that cause ____ produce a fimbrial adhesion termed P. FIMBRAE.
The bladder as mechanisms to effectively wash away bacteria affixed to the bladder wall. E. Coli has fimbriae (pilli), which functions as adhesions. This pilli also functions as a sex pilli during conjugation. Most E. Coli strains that cause Pyelonephritis produce a fimbrial adhesion termed P. FIMBRAE.
E. coli type 1 fimbrae mediate adhesion to ___ cells.
E. coli type 1 fimbrae mediate adhesion to epithelial cells.
E. coli type 1 fimbriae mediate adhesion to epithelial cells. ___ is expressed at the tip of the e. coli, which mediates attachment to a specific receptor called the ____ receptor, found on human epithelial cells.
E. coli type 1 fimbriae mediate adhesion to epithelial cells. FimH adhesion is expressed at the tip of the e. coli, which mediates attachment to a specific receptor called the mannose-containing receptor, found on human epithelial cells.
Streptococcus ____ has a __-protein that mediates adhesion to fibronectin on pharyngeal epithelial cells.
Streptococcus pyogene has an F-protein that mediates adhesion to fibronectin on pharyngeal epithelial cells.
_____ requires fimbriae, FHA (filamentous hemagglutinin) and pertactin for adherence to the respiratory tract epithelial cells. Vaccines containing acellular FHA and pertactin target _____.
Bordatella Pertussis requires fimbriae, FHA, and pertactin for adherence to the resp. tract epithelial cells. Vaccines containing acellular FHA and pertactin target bordatella pertusis.
___ ___ on microbes attach to surface receptors on host cells.
Adhesin-receptor interaction determines tissue specificity (____).
Most pathogens have multiple mechanisms.
Molecular adhesins on microbes attach to surface receptors on host cells.
Adhesin-receptor interaction determines tissue specificity (tropism).
Most pathogens have multiple mechanisms.
Now that the pathogen has attached, it has to multiply and increase in numbers (eaS Meds).
What are some ways the host contributes to dissemination?
List 3
What are ways that bacteria contribute to dissemination?
List 2
Host cell contribution to dissemination:
- Secretions
- Blood
- Lymph
Bacterial cell contribution
- Motility
- Localized production of enzymes (toxins, proteases, DNases)
Flagella motility is utilized by lots of bacteria. What are some examples?
HEV SP
Heavy-SP needs flagella because he is so heavy
H. pylori e. coli Vibria cholerae salmonella Pseudomonas auriginosa
Spirochetes have ____ flagella. They use a __ type motility. Because of their thinness, their ___ flagella (axial filaments), their ___ shape and their motility, spirochetes are more readily able to penetrate host ___ membranes, skin abrasions and enter the body.
Motility and penetration may also enable the spirochete to penetrate ____ into the tissue, and enter ______, blood steam and dissemination to other body sites.
Spirochetes have internal flagella. They use a cork screw type motility,. Because of their thinness, their internal flagella (axial filaments), their corkscrew shape and their motility, spirochetes are more readily able to penetrate host mucus membranes, skin abrasions and enter the body.
Motility and penetration may also enable the spirochete to penetrate deeper into the tissue, and enter lymphatics, blood steam and dissemination to other body sites.
What are some ways that bacteria can evade our innate and adaptive immune system? Act stealthily or attack.
Explain:
Stealth:
Run (antigenic variation, modify surface)
Hide (capsules, biofilms)
Molecular mimicry -“just fit in”
AttacK:
Kill - using toxins
Disarm - using toxins, proteases, and peptidases
Invade - invade tissues or cells
Capsules are usually high in ___ ____, but composed of polymerized simple sugars like ___, __ and ___.
Capsules can be ___ or ___. For example, the bacteria bacillus anthracis capsule is composed of the polymer _____.
Sometimes, the capsules are expressed in vivo, but not in ___. It is ___ variable.
The main function of capsules are to: Prevent \_\_\_ by neutrophils Adhere and colonize Prevent the complement and Ab deposition Prevent decissation.
Capsules are usually high in molecular weight, but composed of polymerized simple sugars like glucose, galactose and mannose.
Capsules can be proteins or amino acids. For example, the bacteria bacillus anthracis capsule is composed of the polymer D-glutamate.
Sometimes, the capsules are expressed in vivo, but not in vitro. It is phase variable.
The main function of capsules are to: Prevent phagocytosis by neutrophils Adhere and colonize Prevent the complement and Ab deposition Prevent decissation.
What are some examples of encapsulated bacteria?
Streptococcus pneumoniae Neisseria Meningitidis H. Influenza Group B Strep Klebsiella pneumoniae Salmonella E. Coli
At the new strip club, for his ENtre, male nossofsky was highly influenced to order the Beef strep, the crab, the salmon but then he got e. coli
Bacterial biofilms: a collection of ____ bacteria bound to a surface and embedded in a self-produced polymeric matrix.
Why do bacteria make this?
To avoid ___ agents and to evade ___ cells, antibiotics, __ species, and __ agents.
Bacterial biofilms: a collection of aggregate bacteria bound to a surface and embedded in a self-produced polymeric matrix.
Why do bacteria make this?
To avoid antimicrobial agents (the more there are, the most resistant), and to evade phagocytic cells, antibiotics, ROS and chemical agents.
In human infection, almost all bacteria we study form biofilms. List the biofilm bacteria that occurs in the following diseases: Dental caries's \_\_\_\_\_ Otitis Media is \_\_\_\_\_ Endocarditis \_\_\_\_\_ Cystic Fibrosis \_\_\_\_\_ UTI and intestinal infection \_\_\_\_\_\_ Nosoconial Infection \_\_\_\_\_ Catheter related infection \_\_\_\_\_
Dental caries's : g+ streptococci Otitis Media is : Haemophilus Endocarditis : streptococci Cystic Fibrosis : pseudomonas UTI and intestinal infection : e. coli Nosoconial Infection : numerous bacteria Catheter related infection : staphylococcus/candida
Endocartidis is an infection of the _____. Once biofilms accumulate, it is very difficult to treat. Usually, people have to get valve replacements
heart valves.
How does bacteria run away?
Two ways
- Antigenic variation
I.E. N. Gonor. expresses pillin protein. This is involved with the attachment to the host cell. What happens is, it expresses the pillin protein and our immune system will produce ab against pilE (expressed pillin). The bacteria senses this and antigenic variation occurs via homologous recombination between expressed locus, and the silent locus. This can occur over a million times, making it very difficult for our immune system to keep up. - Molecular mimicry
–> wear the hosts clothing! Bacteria will mimic host receptors, proteins, etc. You can’t kill what you don’t see (a foreign antigen shares sequences or structural similarities with self antigens).
Bacteria produce or decorate their cell surface with host-like proteins.
How do bacterial engage in frontal attack?
Two Ways:
- Kills - using toxins
2. Disarms - toxins, proteases, and peptidases
What types of bacterial toxins are there?
Endotoxins - expressed by g- bacteria
Exotoxins - expressed by g+ and g-
Toxins inhibit host cells via distinct mechanisms. Some are ___ (kill host cells) and some are ____ (alters cellular pathways, but does not kill cells). The targeted cells are often ____.
Toxins inhibit host cells via distinct mechanisms. Some are cytotoxic (kills host cells), and some are cytotonic (alters cellular pathways, but does not kill cells). The targeted cells are often professional phagocytes.
_____ - double stranded, generally circular DNA sequences that are capable of autonomously replicating in a host cell (like bacteria)
plasmids
____ - or a phage, is a bacterial virus that infects and replicated within bacteria. They are NOT viruses.
Bacteriophage
____ ____ is a DNA sequence that can move from one place to another in the genome, sometimes generating a reversing mutations and altering the cells genome size aka JUMPING GENE.
transposable element
There are two primary mechanisms for generating genetic diversity in bacteria. Both contribute significantly to the natural evolution of bacterial pathogens. What are they?
- spontaneous and random mutations and selection for bacteria with enhanced properties (slower process)
- gene transfer from other microorganisms (rapid)
In bacterial genetics, there are two important terms:
Wild-type and mutant
___ - found most abundant in nature
___ - bacterium that differs genetically from the wt. the mutant has a genotype different from the wt strain which may or may not result in a readily observable trait (phenotype)
In bacterial genetics, there are two important terms:
Wild-type and mutant
wt - found most abundant in nature
mutant - bacterium that differs genetically from the wt. the mutant has a genotype different from the wt strain which may or may not result in a readily observable trait (phenotype)
How does a mutation in pseudomoas help the survival of this bacteria?
A mutation in a negative regulator, MucA result in a high level synthesis of capsular polysaccharide by pseudomonas aeruginosa.
Wt mucA - capsule gene inactive
mutant mucA - capsule gene activated in selected mucA in CF lung. It is the environment of the CF lung that causes the mutation in the negative regulatot mucA, which causes more synthesis of polysaccharide capsule of pseudomoas aeruginosa.
Explain the lac operon
The lac operon is a set of genes responsible for transcribing betty, gail and thio (beta-galactosidase, galatase permease and thiogalactoside transacetylase). These genes are responsible for breaking down lactose. When lactose molecules come into our intestines, they bind directly to the lac-repressor. When lactose binds to the repressor, it falls off, and frees up the operon. Now we get transcription!
Lactose is the inducer that binds to the repressor.
But, repressor mediated transcription control only tells 1/2 of the story. Even if lactose is present, betty, gail and thio will not be produced IF another, more desirable energy source (like glucose) is available.
Lac operon expression also relies on positive regulation. In order for RNA polymerase to effectively bind and transcribe the structural gene, an active CAP protein complex is required. However, the CAP protein is only active when bound by cAMP. When glucose is available, cAMP levels remain low and CAP remains inactive. Under these circumstances, even though lactose is present, little expression of betty, gail and thio is produced. Only whenglucose levels are low that cAMP is high, and CAP activates.
So, without glucose but WITH lactose, cAMP levels are high, CAP is activated, and more betty, gail and thio are produced to break down lactose.
Rifampicin is a drug for treating what? How does it do it?
Mycobacterium tuberculosis (M. TB) It inhibits DNA dependent RNA polymerase of mycobacterium.
What type of gene transfer mechanisms are there? 2 types
Horizontal and Vertical Horizontal gene transfer occurs as: prok to prok prok to euk euk to euk
Vertical gene transfer is the transmission of genetic information from parent to progeny. It is the transfer of DNA by replication
The ___ gene encodes for an altered penicillin binding protein that is proficient for cell wall synthesis but is not inhibited by _____, or ____.
The mecA gene encodes for an altered penicillin binding protein that is proficient for cell wall synthesis but is not inhibited by beta-lactam antibiotics or cephalosporins.
The mecA gene allows a bacterium to be resistant to antibiotics such as methicillin, penicillin and other penicillin-like antibodies
What is MRSA?
Methicillin resistant staphylococcus aureus.
Methicillin was introduced in 1959, MRSA appears in 1960.
mecA is carried on a mobile genomic element called SCCmec (staphylococcal chromosomal cassette).
Penicillin kills bacteria how?
weakening their cell walls. Specifically, they target the enzyme that cross-links the peptidoglycan later in the cell wall. Penicillin is a beta-lactam antibiotic. It belongs to a class of antibiotics that have beta-lactam ring in the structure. Some bacteria can cleave beta-lactam rings by secreting beta-lactamases.
Some scientists created METHICILLIN, which adds a bulky group to the beta-lactam ring, so that the beta-lactamase cannot reach it.
What is SCCmec?
Staphylococcus Cassette Chromosome mec. is a mobile genetic element of the staph bacteria species. This genetic sequence induces the mecA gene, coding for resistance to the antibiotic, methicillin, and is the only known way for staphylococcus strains to spread the gene in the wild by horizontal gene transfer.
What are four ways that bacteria pick up DNA?
- Transformation - uptake of naked DNA
- Transduction
- Conjugation
- Transposition
What is an example of transformation?
Transformation is an important aspect of streptococcus pneumoniae and haemophilus influenza. Capsule genes of non-capsulated strains are acquired by transformation.
What is transduction?
Phages play an important role in infectious diseases.
Infection by a bacterial virus/bacteriophage carrying bacterial genes.
Examples:
- the diptheria exotoxin of the bacterium, Corynebacerium disptheria is produced only when the bacterium is infected with a specific prophage (beta phage)
- the erythrogenic toxin causing symptoms of scarlet fever is produced only when the group A streptococcus is infected with a specific prophage
- the neurotoxin produced by clostridium botulinum is encoded by a phage
- exfoliatin, an exotoxin that causes scalded skin syndrome, is produced by straphylococcus aureus as a result of lysogenic conversion. A lysogenic phage encodes an exotoxin produced by vibrio cholerae
What is conjugation?
- plasmid mediated exchange of info between bacteria in contact
- must touch each other
- plasmic transfer of genetic information
- requires cell to cell contact
- if the F plasmid sequence is intergrated into the bacterial chromosome, the cell is designated an Hfr (high frequency recombination cell)
thin, curved or comma shaped
g- rods, not typically observed by microscope
oxidase +
microaerophilic growth requires elevated 5% CO2 and 42 degrees celcius
Main reservois is the intestinal tract of other animals (transmitted via fecal oral transmission)
aucte enteritis with diarrhea, fever, severe abdominal pain
bloody diarrhea
abdominal pain, mimicking acute appendicitis
reactive arthiritis
guillain barre syndrome
campylobacter
