Pre-Midterm Flashcards
Until recently, _____ was the leading cause of death
Bacterial disease
What types of diseases are people typically killed by?
Respiratory and gastrointestinal diseases
Why is it easier to measure rates of disease in developed countries?
There are more accurate birth and mortality statistics
Epidemiology stats are typically measured in what units?
/100 000 population/year
The crude mortality rate in Canada is ______%
0.71%
What are the top three causes of mortality in Canada? In descending order
- Major cardiovascular disease
- Malignant neoplasms
- Chronic respiratory diseases
______ is almost as common as chronic respiratory diseases in Canada
accidents~
_______ is the infectious disease causing the highest amount of deaths in Canada
Pneumonia
_____ has the highest per capita TB rate in Canada
Manitoba
Canada has a ______ rate of death during pregnancy, childbirth, and perinatal than most industrialized countries
lower
What are the top causes of mortality in Canada due to infectious agents?
- Septicaemia
- Intestinal infections
- HIV
- Hepatitis
- Other infectious and parasitic diseases
Why have HIV rates recently gone up?
Because HIV is no longer a death sentence so people are taking fewer precautions
The most common type of hepatitis that causes death is….?
Hep C
Worldwide, ______ used to be (pre-vaccination) the 4th leading cause of death due to respiratory disease
Measles
Why is the overall rate of diarrhoeal diseases going down?
Clean drinking water
Describe tuberculosis
Respiratory disease occurring in two stages. People have it for life but can go into remission where they show no symptoms.
How was tuberculosis treated before antibiotics?
Often people with TB were sent to live far away so they wouldn’t spread it to anyone. There, they would either go into remission or die alone
What is the most common form of cancer worldwide?
Lung cancer
What are the most common killers in low income countries?
- Heart disease
- Respiratory infections
- Diarrhoeal diseases
- AIDS/HIV
- Tuberculosis
- Neonatal infections
- Malaria
In low income countries, infectious disease amounts to ___% of total mortality
34%
What are the most common killers in high income countries?
- Heart disease
- Cancer
- Respiratory infections
- COPD
- Alzheimer’s
- Diabetes
Infectious diseases cause ____% of the total world mortality
20%
Infants die primarily due to _____
infectious disease
Describe how cholera broke out in a large population following the Rwandan genocide
Following the Rwandan genocide, 500 000 Rwandans were travelling to Zaire, stopping near the border, pooping the whole way. Cholera quickly broke out, killing about 48 000 people. Some also had dysentery and meningitis. Infant mortality rate was extremely high
The _______ survey was conducted by the WHO in 2004 to determine how many deaths worldwide are caused by infectious disease agents
Global Burden of Disease
How are disease rates different between people from high and low income situations?
Even within the US, low income people have much higher disease rates than high income people, likely because they are in better health
Describe the stages of demographic transition and how they relate to mortality rates
Stage I - high fertility, high mortality, low or no population growth (same amount of people living and dying)
Stage II - Decreased mortality, high fertility, increase in population
Stage III - Decreased mortality, decreased fertility, low population growth
What are the 3 groups of mortalities
Group I - Infectious diseases
Group II - Non-communicable diseases, cancer, heart and circulatory disease, degenerative disease
Group III - Accidents and violence
Have cancer rates truly been going up?
No, rates of disease, infectious or otherwise, have been going down, so cancer comparatively looks worse
Describe some theories for the decline in infectious disease mortality
There are many possible causes of the decline, including medicine, evolution, sanitation, nutrition, standard of living. Some scientists think that pathogens simply evolve to be less virulent. Others think that humans evolved to be more resistant.
What are some examples of diseases increasing virulence?
Smallpox (supposedly used to be a benign disease) and 1918 influenza
Why is milk pasteurized?
TB!!!! Cause it’s tasty. Seriously, have you drank unpasteurized milk? It tastes worse than semennnnnnn…that lemons.
_______ is a diagnostic tool for diseases, developed by the WHO, used to monitor incidence and prevalence of diseases. It classifies death and vital records.
International Classification of Diseases
About ____ species of bacteria cause most of the bacterial disease on earth. About ____ of those cause deadly infections
50, 25
TRUE OR FALSE: Most bacteria are opportunistically pathogenic
TRUE
The human body has about a ___:__ ratio of bacterial cells to human cells
10:1
The first bacteria you come in contact with are found where?
In the birth canal
Why is it thought that humans “choose” their bacteria?
All humans are remarkably similar in what grows in their bodies
_____ occurs when live bacteria are found in the blood
Bacteremia
_____ occurs when bacteria are found replicating in the blood
Septiceamia
_____ occurs when viruses can be detected in the blood
Viremia
The _____ and _____ pull bacteria out of your body, helping you to deal with daily infections
Spleen, lymph nodes
What are the mucosal surfaces of the body? What quantity of bacteria grows in each?
Upper respiratory tract - good temperature and pH for bacterial growth
Gastrointestinal tract - perfect conditions, contains most bacteria in body
Urinary tract - does not contain many bacteria, usually too low in pH
Why is it that humans have slightly different bacterial flora?
They all have diverse habitats, diets, clothing, and habits affecting bacteria
Species that are not resident bacteria are referred to as _____
Transients
Describe resident bacterial species
Usually present at all times and on all people, adapt to their environment, reproduce in their environment, hard to displace, and generally cause no health issues
Describe transient bacterial species
Present only sometimes, present only in a sub population (ex. S. aureus in nose), do not show adaptations to human body, usually cannot reproduce, includes most pathogens, also called “commensals”
What is an example of a bacteria that is both a transient and a resident bacterial species
Streptococcus pneumoniae lives only in humans, yet does so very rarely and often not at all in a person’s lifetime.
Most skin bacteria are gram _____. Why is this?
positive. Because they are better at surviving desiccation and high salt concentrations
Most skin bacteria grow where skin is _____
moist
Describe the composition of the skin
Upper layer - Epidermis
Lower layer - Dermis
The epidermis is primarily composed of _____ cells. Describe them
Keratinocytes. Several layers of them exist on top of the skin, dead and providing protection. They are produced in the basal layer and it takes 2-4 weeks for them to migrate to the surface. When the cells slough off it is called desquamination
Why is skin so protective against bacteria?
Salt concentration (high osmotic pressure) - throws off solute balance in cell - inhibits gram negs
Waterproof/dry - inhibits gram negs
Low pH (between 4.5 and 6) - inhibits gram negs
Bacteria cannot penetrate mechanically or enzymatically (cells too fatty and dead)
Desquamination causes most bacteria to be lost daily
Free fatty acids (Long chain fatty acids) - affect gram positives
Lack of nutrients (most bacteria can’t eat keratin, molecules on skin are too large to efficiently digest)
What important structures compose the dermis?
connective tissue, nerves, capillaries, hair follicles, glands, fat tissue, and immune system components
How do bacteria compete on the skin?
Many gram positives secrete antibiotics to inhibit other bacteria and other strains of the same species. Also, some bacteria, when hydrolyzing lipids, release fatty acids which are toxic to other species
What makes up the upper respiratory tract?
Nose, pharynx, larynx, trachea, and bronchi
Describe the Coryneforms. List as many genera as you can
Non-acid fast (except TB), non branching (do not form mycelia), non-sporeforming gram positive pleomorphic rods. Include anaerobic and aerobic species.
Include genera such as Corynebacterium, Propionibacterium, Brevibacterium, Dermabacter, and Mycobacterium.
What is size the nose good at filtering?
> 5 micrometers. The larger the particle the better and more efficient
anything <1 micrometer can just slide right in
What kind of cells compose alveoli?
non-ciliated, simple, squamous, type 1
cuboidal epithelial, extensive microvilli. (These fuckers secrete alveolar fluid and serve as stem cells to replace the Type 1)
How is Propionibacterium acnes potentially related to acne? Can it opportunistically cause any disease?
It is often the dominant species in oil gland with reduced O2 concentration. Can inflame pores by hydrolyzing triglycerides to free fatty acids.
Also can cause endocarditis, endophthalmitis, osteomyelitis, wound/catheter infecitons
What other mucus is also produced?
Airway surface liquid.
CNS stands for ____
Coagulase-negative staphylococcus
Which CNS species are most important, with regard to skin
Staphylococcus epidermidis is most common and widespread on skin - can adhere to skin and medical devices
Other genera found on skin include: S. saprophyticus, S. sapitis, S. hominis, S. haemolyticus
WHAT THE FUCK IS UP WITH STAPH HAEMOLYTICUS
Transferred the methicillin resistance gene to MRSA!!!!!!!!!!~~~~~~~~
Why the fuck do bacteria love our RT so much?
host anti-microbial defenses large populations of Gram-negatives as well as Gram-positives larger populations higher species diversity frequent isolation of pathogens ability to attach to epithelial cells
Found on the skin, describe the yeast Malassexia
Oval/cylindrical, lipophilic, dimorphic. Are superficial to skin. Associated with dermatitis, dandruff, foliculities, pityriasis, versicolour.
How are organisms often transferred to and from the skin?
Contact transmission to/from inanimate objects, people, other parts of the body. All bacteria and viruses can be transferred - often people touch things like their lips and nose, and that’s how they get sick
Shedding of sqaumes rids the skin of millions of bacteria every day
Hand washing helps to reduce transmission of infectious disease
Describe how invasive hospital procedures such as catheters, IV lines, and surgery can lead to nosocomial infection. Which bacteria often cause the infections?
Often results in septicemiae, with a 10-15% mortality rate. 50-75% of nosocomial septicemia is caused by Staph epidermidis
Implantable devices can infect the host.
Wound and surgical site infections can be colonized by CNS, P. acnes, or Corynebacterium species.
Organisms include S. aureus, Propionibacterium acnes, Staph epidermidits and numerous gram negatives
What are the main bacterial genus of the mouth?
Oral Strep Actinomyces Veillonella spp. Fusobacterium Porphyromonas
What does the acronym EVIL stand for?
Every
Villain
Is
Lemons
How do bacteria compete on the skin?
Many gram positives secrete antibiotics to inhibit other bacteria and other strains of the same species. Also, some bacteria, when hydrolyzing lipids, release fatty acids which are toxic to other species
How does the human immune system protect against bacteria on the skin?
- We secrete antibodies, which are thought to stop bacteria from attaching to skin
- Antimicrobial peptides in very short chains, such as “defensins”, cationic peptides effective against gram pos and gram negs, fungi. Also includes dermicidin
- Lysozyme: works best at low pH and high salt conc. Breaks down peptidoglycan and works better on gram positives. This is secreted onto the surface of the skin, eyes, and mouth
- Reactive nitrogen species: H2O2 on the skin forms nitric oxide which can be lethal to cells
Describe important pathogens in the Corynebacteria
Corynebacterium diptheriae - Respiratory tract pathogen
C. urealyticum - causes nosicomial UTIs
Describe the genera Propionibacterium
Proteolytic (can feed corynebacteria) and liplytic. Can be microaerophilic or anaerobic.
Describe the coagulase-negative Staphylococci (genus Staphyloccocus)
Includes all Staphyloccoci but S. aureus. Most inhabit mammals, and almost half of species can be found on human skin. Tolerate wide pH and temperature range, very halotolerant.
CNS stands for ____
Coagulase-negative staphylococcus
Which CNS species are most important, with regard to skin
Staphylococcus epidermidis is most common and widespread on skin - can adhere to skin and medical devices
Other genera found on skin include: S. saprophyticus, S. sapitis, S. hominis, S. haemolyticus
Is S. aureus commonly found on the skin?
Nope, usually found in the nose.
Found on the skin, describe the yeast Malassezia
Oval/cylindrical, lipophilic, dimorphic. Are superficial to skin. Associated with dermatitis, dandruff, foliculities, pityriasis, versicolour.
How are organisms often transferred to and from the skin?
Contact transmission to/from inanimate objects, people, other parts of the body. All bacteria and viruses can be transferred - often people touch things like their lips and nose, and that’s how they get sick
Describe how invasive hospital procedures such as catheters, IV lines, and surgery can lead to nosocomial infection. Which bacteria often cause the infections?
Often results in septicemiae, with a 10-15% mortality rate. 50-75% of nosocomial septicemia is caused by Staph epidermidis
Implantable devices can infect the host.
Organisms include S. aureus, Propionibacterium acnes, Staph epidermidits and numerous gram negatives
What is the only bacteria in the stomach?
Helicobacter pylori
Describe “amensalism”, give an example within bacteria
One organism adversely affects another. Ex. antibiotic production to inhibit competitors
Describe “parasitism”, give an example within bacteria
One (the parasite) benefits while the host suffers
Ex. most bacterial/all viral infections
How are bacteria subject to predation?
Bacteria can kill each other - ex. Bdellovibrio and Vampirococcus
Protists often kill bacteria in their natural environments. However, some bacteria just live inside their captors. Stockholm-syndrome like.
Describe “commensalism”, give an example within bacteria
One symbiont benefits while the other is neither benefited or harmed.
Ex. Facultative anaerobes consuming most O2, the nstricter anaerobes can survive
How can H. pylori survive in the stomach?
It has a flagella that allows it to penetrate the mucuosal membrane of the stomach and catalyzes urease into ammonia which increase the pH of the stomach to a point where it can survive.
Describe “mutualism”, give an example within bacteria
Obligate symbiosis with benefit to both parties. Good example is Buchnera aphidicola and aphids. Bacteria ferment the sugars in plant sap and release amino acids for aphid. Bacteria cannot live outside of aphids and aphids treated with antibiotics die
There is a low amount of bacteria duodenem, what are the genuses that inhabit it?
Lactobacillus and Strep (Both have to be acid tolerant) Bacteroides Clostridium Entrococcus Enterobacteria
Describe the Enterobacteriaceae of the large intestine (include genera)
Facultatively anaerobic, mostly motile, gram negative (small) rods. Most common are Escherichia, Proteus, Enterobacter, Citrobacter
What can be used as a representative image of the body?
Poop, its poop.
It contains 10 to the 8 cells/gram for facultative anaerobes and 10 to the 11 cells/gram of obligate anaerobes.
What is the main source of carbon in the large intestine?
Complex carbohydrates from plants
cellulose/hemicellulose
pectins
xylans
mucoproteins, glycoproteins, and glycolipids
Describe “cooperation”, give an example within bacteria
Both symbionts benefits but the relationship is not obligatory. Ex. I don’t want to explain it, it’s that long thing about SCFA fermentors and H2 consuming methanogens
How do bacteria gain nutrients and essential things in the large intestine?
Bacteroids consume the complex carbohydrates and break them down. Then Eubacteriums consume these simple sugars and change them into SCFA (short chain fatty acids). Clostridium and Enterococcus also ferment the sugars, but they instead ferment them into acids.
What is “symbiosis” between organisms? What are the types of symbiosis?
Two different organisms living together, usually in close proximity, may be permanent
If there is a large difference in size the larger one is often called the “host”
Endosymbiosis = one inside the host, often intracellular
Ectosymbiosis = outside the host
Describe Peptostreptococcus
Obligately anaerobic, gram positive cocci in pairs, tetrads, and clusters. Very strictly anaerobic, which makes one wonder how they even got there. Performs amino acid fermentation
What’s an antibiotic?
Substance produced by a living organism that kills or inhibits bacterial growth
What does it mean to be bacteriostatic?
Inhibits growth of bacteria until removed from your system, then the bacteria can grow again
What does it mean to be bacteriocidal?
Bacteria are killed
Is it necessary for antibiotics to be bacteriocidal to be effective?
No, bacteriostatic ones can inhibit growth enough to give your immune system a chance to strike
how are antibiotics tested for effectiveness?
Vials are produced containing the same amounts of bacteria but different amounts of antibiotics (half of the previous vial and so on). The vial with no growth that had the smallest amount of antibiotic added gives us the Minimum inhibitory concentration (MIC). Then, the organisms from each of the “no growth” vials are plated, and if something grows, the antibiotic is only bacteriostatic
Differentiate between wide and narrow spectrum antibiotics
Wide spectrum - work against many types of bacteria
Narrow spectrum - effective against only one type of bacteria
Differentiate between MIC and MLC
MIC - minimum inhibitory concentration - lowest concentration of antibiotic needed to stop growth of that species
MLC - minimum lethal concentration - lowest concentration of an antibiotic that kills all bacteria of a given species
What are the 4 main targets of antibiotics
- Antimetabolites
- Cell wall (peptidoglycan) Biosynthesis
- DNA-RNA Biosynthesis
- Protein Biosynthesis
Describe how antimetabolites work. What form do these antibiotics come in? What spurred their development?
interfere with cellular metabolism (usually small molecule metabolism. Antibiotics are all synthetic, called sulfonamides (sulfa drugs).
In the early 1900s a mostly toxic antibiotic called Salvarsan was used to treat syphilis, and people thought they wanted something much less toxic
Describe the antibiotic “sulphanilamide”. How does it work and what does it inhibit?
Sulphalimide inhibits –aminobenzoic acid, an essential component in the development of folic acid. Folic acid is necessary for biosynthesis of purines, pyrimidines, methionine.
Inhibits Group A strep, Strep. pneumoniae, Staphylococci, Neisseria spp, Haemophilus influenzae, Bordetella pertussis, Yersinia pestis, Chlamydia
Most suphonamides are not used because of toxicity and resistance but some are still used in treating UTIs as they concentrate in the urine
What type of antibiotic is Penicillin?
Peptidoglycan synthesis inhibitor
Who “discovered” (in a lab) penicillin?
Fleming
What is penicillin most useful against?
Staphylococci, pneumococci (ex. Streptococcus pneumoniae), Meingococci (ex. Neisseria meningitidis), Gonococci (ex. Neisseria gonorrhoeae)
NOT gram negs
Describe the structure of penicillin
beta-lactam ring is what attacks peptidoglycan. Whatever is attached to it just affects the properties of the antibiotic, but the beta-lactam ring is the most important part
What are the six major classes of penicillin used today?
- Penicillin G
- Penicillin V (oral)
- Penicillins resistant to Staph Beta-lactamase
- Broad spectrum (amino) penicillins
- Penicillins active against P. aeruginosa
- Beta-Lactamase resistant Penicllin
Describe the Benzyl Pencillins (Penicillin G)
The original, which was a crystallized penicillin. Acid labile, effective against most gram positives. Still the antibiotic of choice against S. pneumoniae, N. gonorrhoeae, Staphylococci that are not resistant, and Beta haemolytic Streptococci.
It is cheap and nearly non toxic
Describe oral penicillins (Penicillin V)
Acid stable, just like Penicillin G but can be taken orally
Describe Penicillins resistant to Staph Beta-lactamase
Used to treat penicillin-resistant Staph infections. Basically, the extra part of penicillin is cleaved off and the beta lactam ring is left over (makes it semi synthetic).
Includes Methicillin (as in MRSA), oxacillin (form used in North America), cloxacillin, flucloxacillin.
MIC is higher in this than Penicillin G and V, basically just used for resistant species
Describe the Broad spectrum Penicillins
Better against gram negs, still active against gram positives, not resistant to Beta-lactamase.
ex. amoxicillin (ideal because it is cheap and safe)
Describe penicillins that are active against P. aeruginosa
P. aeruginosa doesn’t do much to the body unless you have a condition like cystic fibrosis, then it can be fatal. In those situations penicillins like ticarcillin and carbenicillin are used
What is the only beta-lactamase resistant penicillin
temocillin
What are the Cephalosporin antibiotics?
Related to penicillin, still have beta lactam. Basically the same as penicillin but has a slightly wider spectrum of activity. Resistant to Staph beta-lactamase. This was the basis for semi-synthetic antibiotics and we currently use over 25 of them
Describe the first generation cephalosporins
Cephaloridine was the first in use, effective against penicillin-resistant S. aureus, streptococci, E. coli, K. pneumoniae and Proteus mirabilis
Describe the second generation cephalosporins
Cefoxitin. Resistant to gram negative beta lactamases. Can attack the same as first gen plus Haemophilus and Enterobacter
Describe the third generation cephalosporins
Effective against P. aeruginosa, almost all enterobacteriaceae, Neisseria gonorrhoeae
Vancomycin was the antibiotic of choice when treating MRSA for a while, why was it an issue?
SUPER toxic, lots of side effects
Describe the Carbapenams
acid labile, last resort antibiotic. similar to beta-lactams, highly resistant to beta-lactamases and cephalosporinases. Wide spectrum against gram pos, neg, include P. aeruginosa and MRSA. Last resort because we do not want things to develop resistance
Describe protein synthesis inhibitors
most diverse antibiotics, rely on differences between eukaryotic and prokaryotic ribosomes (low therapeutic index), often can be toxic or have side effects
What is the therapeutic index?
toxic dose/therapeutic dose
What is used to treat herpes?
Cidofovir
What are the three kinds of antivirals that target HIV?
Nucleotide analog reverse transcriptase inhibitors
Non-nucleotide RT inhibitors
HIV protease inhibitors
Describe tetracycline
Introduced in the late fourties, bacteriostatic, blocks binding of amino-acyl tRNAs to ribosomes
Effects Staph, Strep (not Enterococci), many gram negatives (not P. aeruginosa), Mycoplasmas, Chlamydia and Richettsia, Spirochetes.
this antibiotic is limited by resistance and minor toxicity. Used to treat intracellular bacteria, STIs, respiratory infections, UTIs.
Describe the Macrolides
Have a very large lactone ring. Bacteriostatic, wide spectrum of activity, end in “thromycin”. Are protein synthesis inhibitors. good against gram negs but not gram pos. Used as an alternative to penicillin when patients are sensitive (basically a shittier penicillin). Antibiotic of choice for Corynebacterium diphtheriae, whooping cough (Bordetella petsusis) and Legionnaire’s Disease (Legionella pneumophilia).
Also used to treat CAP (community acquired pneumonia), mycoplasma infections, and non-TB mycobacterium
What is the primary DNA Synthesis Inhibiting antibiotic> Describe them
Fluoroquinolones. used to treat UTIs and effective against gram negs (incld. P. aeruginosa - with a good MIC), and some gram pos (staph, strep, enterococcus).
over generations they got less toxic and more expensive
Often used to treat respiratory tract infections, UTIs, nosocomial gram-neg infections
Describe RNA synthesis inhibitor antibiotics
inhibit DNA dependent RNA polymerase, bacteriocidal, very narrow spectrum of activity (gram pos, neisseria, mycrobacterium.
Used in meningitis outbreaks, as part of multi-step TB treatment
