Microbiology

Microbiology is the study of microorganisms. They can be single cellular, multicellular, or acellular. Microbiology incorporates numerous disciplines found within the field of microbiology.
Disciplines are:
• virology
• mycology
• parasitology
• bacteriology
The years from 1857-1914 are called the Golden Age of Microbiology. Some of the famous members found within this field are:Famous Microbiologist

Binomial nomenclature is composed of two italicized words. The first word which is the Genus, is capitalized, and the second word, is the species designation, is in smaller case.

The standard resource for identifying prokaryotes, bacteria, is Bergey’s Manual of Determinative Bateriology.

To be seen without a microscope, it needs to measure about 100 micrometers.  Most microorganisms are smaller than that.  Microorganisms differ between each other in size, structure, habitat, metabolism as well as other characteristics.  Micros are found in Archaea, Bacteria, and Eukarya life domains.

Microbes in the Bacteria & Archaea domains are all prokayotes (lack nucleus).  Cyanobacterium is a prokayotic microorganism.  Eukaryotes are Eukaya (has nucleus)Viruses although are microorganisms do not fall within any of the domains of life.  Virus is acellular.  Peptidoglycan is the ones with cell walls.

Bacteria is a prokaryot because their DNA is not within a true nucleus.  It is found everywhere.  Yeast is a type of fungal microorganism.  Alga is photosynthetic.

Otzi te Iceman was discovered frozen in the Alps.  Scientists believe that he died of Lyme disease.

Pathogens cause disease.  Most are good.  They are named for shape.  Common shapes are spherical (coccus), rod-shaped (bacillus) or curved (spirillum), spirochete, or vibrio.  Bacteria is very versatile.

Archaea unicellular prokaryote.  They are different from bacteria in their evolutionary history as well as numerous other differences.  Their cell walls are psuedopetidoglycan. None of these have been shown to be a pathogen.

Please refer to your book for addition information.

Ebola

Clinical Symptoms

  • Incubation period—Approximately 43 days
  • Acute illness with rapid onset of fever (104⁰ – 109⁰ F)
  • Sore throat
  • Massive vomiting
  • Diarrhea (3 gallons/day)
  • Poor Kidney Function
  • Poor Liver Function
  • Internal & External bleeding (bleed out of every body opening)
  • Lyses or bursting of Red Blood Cells (RBC)

Treatment

None

Hydrate Slow vomiting & diarrhea Antibodies boost the immune system.  They do not kill viruses

Structure

  • 850 -920 nanometers
  • Single strand of RNA virus
  • Non-Segmented
  • Long thread-like linear molecule
  • Has an extra protein coat

Ebola is a member of the filovirus family (Marburg virus).  Filovirus can cause severe hemorrhagic fever, which symptoms are, fever, vomiting, prostration, petechial hemorrhages, hypotension, and muscle pain.  There are only two members of this virus family (Ebola & Marburg virus).  Ebola have five strains with one Ebola-Reston not causing severe disease in humans.

The Filovirus was discovered in 1967 in Germany and Yugoslavia.  Researchers were analyzing tissue of a green monkey, which had the disease.  Researchers contracted the disease.  This virus was named after where the outbreak occurred Marburg, Germany.  Ebola was first discovered in 1976 in Africa.  There is some evidence that it was originally contracted from bats.  Once humans are infected, it spreads from person to person.

Death rate is 23 to 90%.  To reduce risk of contracting from another human wear PPE, do not have contact with bodily fluids such as blood, and other secretions.  Do not expose yourself to animals out of Africa, which may have the disease.

Currently the medical community is working on a vaccine.  Researchers at Howard Hughes Medical Institute have developed at blood test (Virscan) which will tell doctors the patient complete viral history.

The information provided above was from my Microbiology class.  In writing this blog, the CDC and MedicineNet.com were used as references.  Please check out the video on PBS Frontline called “Ebola”.

Ebola was named after the Ebola River where it was first discovered.  There were two major outbreaks in the 90’s and one in Northwest Africa in 2014.  Death occurs within six days.

In the United States there are only 19 negative pressure beds.  The closest to Louisiana is Atlanta which has four.

Ebola is an enveloped virus meaning it has an extra protein coat.  It is hard for drugs or immunity virus to attach & destroy.

Glycoproteins live on surface of virus.  These glycoproteins are made up of carbohydrate chains called glycans.  There are two types:

  1. GP1-Attachment (which makes it more potent)
  2. GP2-Fusion of host and viral membranes.

Genus Bacillus – gram positive, aerobic
spore -forming rods
Largely saprophytic & doesn’t cause
Importance in food preservation

Passion is the genius of genius  – Galileo
Do or not do.  There is no try.  – Yoda

Microbes weigh as much as our brain which is 3 lbs. in our body.  We have around 65 different microbes in our belly button

Human Perspective on Micro

  1. Activities of microbe are responsible for all life on earth.  We have to have fungus.
  2. Bacteria fix nitrogen so plants can feed breaks down nitrates or nitrites.
  3. Microbes replenish our oxygen.  Phytoplankton
  4. Microbes degree organic pollutants & toxic waste.
  5. Food stuff:  Cheese, sauerkraut, yogurt, kimchee, bread (yeast), mushrooms, root beer, beer, moonshine, and wine
  6. 90% of antibodies are made by microbes.
  7. Genomics – use fungi for their restriction enzymes
  8. Medical microbe
    1. old world disease –plague, TB, yellow fever
    2. emerging world disease – Ebola, trichomonas, aids, west nile, H1N1 (West Nile)

Vinods

1/10 the size of a virus
no outer coat
cause plant disease
short strands of RNA

Prions (Protein only infectious particle)  Short strand Protein

  1. Induce other proteins to become prions
  2. Inheritable
  3. Cause neurogenerative disease
  4. can last for years after death
  5. can penetrate surgical gloves

These are all pan resistant which means no antibiotics affect them:

  1. Stenotrophomonas maltophilia enzyme (S. Malt), New Delhi metallo beta lactamase type enzyme (NDM1), Klebsiella pneumoniae carbapenemase (KPC)

Watch Hunting the Nightmare Bacteria on Frontline

Quantum Dot Stain-New

Microscope & staining

Microscopy

  1. light
  2. electron
  3. atomic force

Staining

  1. Basic dyes- stains negatively-charged part of cells (nucleic acids, proteins) dyes used:  crystal violet, safranin, methylene blue, malachite green
  2. Acidic dyes-stains the background as in a photographic negative, called negative staining, dyes used nigrosine, India ink

Mordint

Simple stain

  1. glass slide & place a drop of H2O in the center
  2. Take your inoculating loop & put it in the burner
  3. *Take the heated loop & dip it in your culture.  Take the loop put it in H2O droplet & spread all over the slide.  This is called a smear.
  4. *Heat “fix” the slide over the hot plate
  5. Place a drop of methylene blue or crystal violet on the slide.  Let it stand for one minute.  Rinse with water, blot dry & observe

Gram Stain

  1. Prepare smear & fix
  2. Flood the smear with primary smear-crystal violet let it stand 1 minute & rinse with H2O.
  3. Flood smear with Gram’s iodine.  Let it stand one minute.  Rinse with H2O.  Iodine acts as a mordant.  Mordant increased the likelihood of a structure to take up stain.
  4. Take 95% ethanol and drop by drop rinse the smear.  Rinse with H2O.  E + OH (ethanol) decolorizes gram negative bacteria.
  5. Flood the smear with your counter stain which is safranin.  Let it stand 30 seconds.  Rinse with H2O blot dry & observe.  Crystal violet will stain gram + purplish to blueish

Safranin stain gram negatives pink – reddish color.

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Bacterial Morphology

1.      Spherical or round – coccus
2.    Rod or cylinder – bacillus
3.    Spiral – spirillum
4.    Short, curved rod – vibrio
5.     Star shaped – prosthecae

Some prokaryotic (bacterial structures)

1.      Ribosome – make protein
2.    Plasmids – small, circular strand of DNA
3.    Nucleoid – twisted DNA strand
4.    Glycocalyx – layer of polysaccharide lying inside bacterial cell wall
5.     Apendayes-
a.     Pilus
b.    Flagella- consists of a hook for rotation, basal body for anchoring, filament tail for movement

Types of flagella

1.      Monotrichous – single flagella–has tail as one end see example  

2.    Amphitrichous- flagella at both ends—has tail at both ends see example ~

3.    Lophotrichous-tuft of flagella—has tufted tails on bottom see example

4.    Perithrichous-flagella all over—has tufted tails all over see example

Biofilms

Communities or group of microorganisms that attach to the surfaces of animate objects, heart valves, bone tissues, etc and inanimate structures prosthetic in plants, catheters, etc. only effective treatment K removal of infected tissues

Bacterial Colonies

Identify by:

1.      Form shape
2.    Elevation- cross section
3.    Margin-magnified edge of colony
4.    Surface-appearance
5.     Opacity-clear, opaque, translucent
6.    Chromogenesis-color
7.     Consistency
8.    Odor
9.    Emulsifiability

Rudolph Virchow (1821-1902)

1.      Father of modern day public health
2.    Shaped modern day public health
3.    Discovered correlation between cancerous & normal cells, modern day autopsy procedures, hair analysis
4.    Names: leukemia, chordoma, embolism, thrombosis, agenesis, parenchyma, osteoid, spina bifida

Anton von Leeuwenhoek

1.      Father of microbiology
2.    Discovered protists & bacteria
3.    Distilling H2O to kill contaminants
4.    Described bacterial motility
5.     Single-celled (ocular) microscope
6.    Most published author in the Royal Society of Great Britain

William Jaffray

1.      Scotsman
2.    Lived near Stirling
3.    Interest was in eradication of small pox through variolation & family & neighbors using variolation
4.    After 1796, he inoculated 500 nearby families, 2 families chose no inoculation
5.     President of Royal Society gave him equipment to do much more inoculation.
6.    Set up shop in his cottage (1808), travelled throughout Scotland inoculating people.  Took neither payment nor a meal.

Endospores

1.      Dormant form of a bacterium that is formed by reorganized the cytoplasm.
2.    Spore has great resistance to outside influences heat, radiation, dessication, chemicals
3.    Can remain dormant for years   50-100 years
4.    Will germinate if conditions become favorable
5.     Size, shape, & position of an endospore is constant within a species & has taxonomic value

Types of Endospores

1.      Central-middle of cell
2.    Terminal-end of cell
3.    Subterminal-between middle & end

EMB agar (eosin methylene blue)

1.      Selective & differential
2.    Used to isolate gram (-)
3.    Methylene dye in small amounts
4.    Eosin dye responds to changes in pH – colorless to black under acidic conditions
5.     EMB contains lactose & sucrose, but no glucose for energy

Lactose fermenting bacteria (usually enteric) acidify EMB & colonies appear black with green sheen (E. coli, Klebsiella, Enterobacter)

Lactose non-fermenters are translucent to pink (salmonella, shigella, and pseudomonas

The EMB selects for growth of gram (-) bacteria & differentiates between genera of gram (-)

We must be willing to get rid of the life we have planned so as to have the life that is waiting for us.  Joseph Campbell

Dynamics of Prokaryotic (Bacterial) Growth

Only 1% of all prokaryotes can be cultured as a pure culture.  You need a good growth medium to grow which is agar.  It was developed by Robert Koch.  Agar is:

  1. specific nutrient solution
  2. degraded by bacteria
  3. translucent
  4. destroyed at high temperatures

Environmental factors that influence microbial growth are temperature, oxygen, pH, water.

Temperatures:  psychrophiles, phychrotrophs, and mesophiles
Oxygen:  obligate aerobes obligate anaerobes facultative anaerobes microaerophiles, aero tolement anaerobes
pH:  neutrophiles, acidophiles, alkalophiles
Water:  halophiles-love salty water

Cultivating Prokaryotes

  1. complex media
  2. chemically defined media
  3. selective media- adds ingredients that inhibit the growth of orgs other than the one bring sought
  4. differential-contains an ingredient that can be changed by bacteria in a recognizable way.

hemolysis

The zone hemolysis is the area where blood is breaking down.  The above are examples.  Please refer to professor notes for the example he/she gives.

Detecting and Meaning

Bacterial Growth

  1. direct cell count
  2. direct microscopic count
    1. coulter counter
    2. flow cytometer
  3. viable (alive) cell count
    1. most probable #
    2. plate count
      1. pour plate
      2. spread plate
  4. membrane filtration

Growth curve

Bacterial Growth

  1. direct cell count
  2. direct microscopic count
    1. coulter counter
    2. flow cytometer
  3. viable (alive) cell count
    1. most probable #
    2. plate count
      1. pour plate
      2. spread plate
  4. membrane filtration

Growth curve

5 stages

  1. lag-extensive macromolecule & ATP synthesis
  2. Exponential or log – cells multiply exponentially
    1. primary metabolite – used as flavoring agents & food supplements
    2. secondary metabolites produce antibiotics
  3. stationary phase-#of viable (living) cells stay constant
  4. death-#of viable cells decrease exponentially
  5. phase of prolonged decline-gradual decrease in # of viable cells overtime (days, weeks, years, and decades)

Microbial growth

controls-

  1. physical – heat, wash, filter, irradiate
  2. chemical-antimicrobial chems

sterilization – removing of or destroying all microbes on or in a product.  Disinfection-eliminating most or all disease

Situational Considerations

  1. daily life
  2. hospitals
  3. labs
  4. food & food production

Using heat to destroy

  1. moist heat
  2. dry heat
  3. pasteurization
    Why is heat so good?  It is cheap quick

Chemicals

  1. sterilants
  2. disinfectants

Potential risk of infection

  1. critical items – scalpel, gloves, needles
  2. semi-critical – endoscope, trachea tube
  3. non -critical –  bp cuff

Selecting the appropriate germicide

  1. toxicity
  2. activity in the presence of organic matter
  3. compatibility
  4. residue
  5. cost
  6. storage & stability
  7. environment risk

Preservation techniques

  1. refrigerate, freeze, lypophilize – freeze dry
  2. salts
  3. sugars

Classes of Germicides

  1. alcohol-antiseptic  kill bacteria & fungi
  2. aldehydes – formaldehyde, inactive proteins & nuclei acids
  3. br guanides – antiseptic, chlorhexide kills bacteria & fungi
  4. ethylene oxide – gas, kills microbes & endospores
  5. halogens, CHI disinfect drinking waste water
  6. ozone- same as halogens
  7. metals  silver, inhibits protein & enzyme function   Copper is the best of these
  8. peroxygen H2O2 – sterilize juice & milk juice containers
  9. Pheholic compounds triclosan & hexachlorophene  – denatures proteins
  10. Quats – food prep surfaces

Human Microbiomes

Disinfection in clinical and non-clinical setting ways to disinfect non-porous surface

  1. steam
  2. mists
  3. foams
  4. UV
  5. liquid disinfectants
  6. microbiocide surfaces

Chemical disinfection

Most are ineffective and harmful.  Why?  Very, very long contact time}hospital centered or a hospital setting

Gases, Mists, Foams

sit for 2-24 hours, seal the room and be unoccupied

Ozone O3

Disinfect rooms, use it as a gas, Dangerous- lead to free radical formation in cells.

Cancer

Questions they must ask if a tumor appears cancerous

  1. Size of primary tumor
  2. Has it invaded surrounding tissue
  3. Has it metastasized (spread)
  4. Has it invaded any regional lymph nodes

TNM System for Identification

T = Tumor

T0 = no tumor;
T1  = very small;
T2  = small;
T3  = medium;
T4  = large

N = Lymph node

N0  = no nodes involved;
N1  = 1 node involved less than 3 cm;
N2  = medium node involved  3-6 cm & multiple small nodes;
N3  = single node larger than 6 cm

M = Metastasized

M0  = no spread;
M1  = spread

Diagnosis = clinical symptoms
Prognosis = probable outcome

Cancer treatments

  1. Surgery
  2. Chemo
  3. Radiation

Cancer Warning Signs

  1. lump or thickening in the breast or elsewhere
  2. nagging cough or hoarseness
  3. changing appearance of mole or wart
  4. indigestion or difficulty in swallowing
  5. change in bladder or bowel
  6. unusual bleeding or discharge
  7. sore that doesn’t heal

Staph – becoming XDR

staph

Pyogenic – pus producer

Staphylococcus aureus

  1. Gram positive
  2. Spherical
  3. Non-Motile
  4. Produces no spores
  5. Colonies are round, raised, golden yellow

Toxin and Enzymes

  1. Staph produces an enzyme called betalactamase – makes it resistant to penicillins and cephalosporins
  2. Cell wall structure is unique and resistant to methicillin (MRSA – methicillin resistant Staph aureus)

Side note: CAMRSA – Communicative associative methicillin resistant staph aureus

  1. Plasmids (round circular piece of DNA) – carry genes resistance tetracyclines, amino glycosides, and erythromycins
  2. Exhibits “tolerance”. Inhibits but not killed
  3. Exotoxin – skin necrosis (rotting)
  4. Exotoxin C – fever producing (106° F)
  5. Hemolysins – cause red blood cells to burst
  6. Leukocidins – kills white blood cells
  7. Enterotoxin – food poisoning
  8. Coagulase – causes plasma to clot
  9. Hyaluronidase – spreading factor
  10. Exfoliative toxin – causes “scalded skin” syndrome
  11. Postulated toxin – causes TSS – toxic shock syndrome

Other manifestations:

  1. Empyema – accumulation of pus in a body cavity
  2. Severe acne
  3. Impetigo – small pustules that ooze a yellowish mustard like liquid
  4. Pneumonia (pus in the lung)
  5. Meningitis
  6. Endocarditis

Treatment Options

  1. No vaccines
  2. Drain lesion
  3. Best medications – vancomycin, clindamycin, rifampin, mupirocin (cream that can be used in the nasal cavity)

Vaccines – substances that are found in vaccines:  (1.2 – 2B people saved from vaccinations)

  1. Aluminum – act as an adjuvant (enhances) to promote a more potent response and a more persistent response.
  2. Antibiotics – prevents the growth of germs during production and storage of the vaccine.
  3. Egg protein – used in production of influenza and yellow fever drugs.
  4. Formaldehyde – inactivates bacterial products for toxoid vaccines, kills unwanted viruses and bacteria that might contaminate the vaccine during production. It is removed from the vaccine before packaging.
  5. MSG – stabilizer for the vaccine in the presence of heat, light, acidity or humidity.
  6. *Thimerosol – mercury containing preservative that prevents growth of harmful bacteria.

Herd immunity – protecting a whole community from disease by immunizing a critical mass of its populace.

Vaccine protects not only the one person, but breaks the chain of an infection’s transmission, it also protects non-immunized individuals.  To do this a certain % of the populace must be vaccinated.

Ways to become immune to a disease

  1. Be exposed to a pathogen
  2. Vaccinate

Infectious features of a microbe.

  1. Transmissibility
  2. Severity

These affect a disease’s threshold (minimum % of an immune individuals and community needs to prevent an outbreak

To set a threshold one uses a value – basic reproductive # or RO

The RO represents how many people in an unprotected population, one infected person can pass the disease along to

RO for measles is 12-18

Polio 5-7

Higher the %, higher the immunity threshold must be to protect the community

Measles 95%

Polio 80%

Factors involved in calculating a specific threshold:

  1. How effective the vaccine for a given disease is?
  2. How long lasting the immunity is from vaccination and infection?
  3. Which populations form critical links in transmission of the disease (very young, very old, immune compromised, religion groups)

 

Disease RO Threshold %
Mumps 4-7 75-86
Polio 5-7 80-86
Smallpox 5-7 80-85
Diphtheria 6-7 85
Rubella 6-7 83-85
Pertussis 12-17 92-94
Measles 12-18 83-94

Koch and germ theory of disease

Robert Koch (1843-1910), physician, studied anthrax early on in his work.  It is a disease of cattle, sometimes people.  Caused by Bacillus anthracis – endospore former.  Koch established that anthrax bacteria were ever present in the blood of an animal with anthrax disease.  He demonstrated that one could take a small amount of blood from a diseased mouse and inject it into a 2nd disease-free mouse.  This mouse then contracted anthrax and died.  He took blood from the dead mouse, injected it into another mouse and it got the disease.  Furthermore, he found that one could cultivate the bacteria in nutrient-rich fluid outside of an animal body and that after many transfers in other cultures, the bacteria was still highly pathogenic.  From these experiments he formulated his famous Koch’s Postulates.

Koch’s Postulates

  1. The organism should be constantly present in animals suffering from the disease and should not be present in healthy individual.
  2. The organism must be cultivated in a pure culture away from the animal body.
  3. Such a culture, when inoculated into susceptible animals, should initiate the characteristic disease symptoms.
  4. The organism should be reisolated from these experimental animals and cultured again in the lab after which it should be the same as the original organisms.

Summary of the postulates: specific organisms cause specific diseases.

Stenotrophomonas maltiphilia (aerobe)

Multi-drug resistant, Gram (-) bacillus, opportunistic pathogen particularly in hospitalized patients.

It has an inherent ability to adhere to foreign materials and form a biofilm, thus, it is protected from host antimicrobial agents.

It has intrinsic or acquired resistance mechanisms to: betalactamases, penicillinase, cephalo-sporinase, aminoglycoside acetyl transferase to confer resistance.

Epidemiology

High morbidity (clinical symptoms – fever, etc)

High mortality (21-69%)

Risk factors for acquiring an S-malt infection: ICU, vented, HIV, cancer, CF, catheters, surgery, broad-spectrum antibiotic treatment.

Need strict hand hygiene and contact isolation.

Clinical manifestations – pneumonia, bacteremia, endocarditis, mastoiditis, peritonitis, UTIs, soft wound infection, ocular infection, meningitis.

Treatment – hard to discern from other infections.  Need much clinical data. Only somewhat effective treatment is:

TMP-SMX +/or

TCA +/or ciproflaxin

14 day treatment span

About 41% effective

Diversity of Prokaryotes

Organohalide respiring bacteria – use chlorinated molecules

Methanogens – oxidize hydrogen gas, make methane

Purple sulfur and green sulfur bacteria – use sulfur compounds, grow in large masses in sulfur springs.

Lactic acid bacteria – make lactic acid.  Can cause disease and make dairy products (yogurt) – Lacto bacillus

Streptococcus pyogenes – cause disease – wound infections, strep throat, rheumatic fever, glomerular nephritis, flesh-eating, TSS

Nitrifers – oxidize NH3 and nitrate, breakdown N

Bioluminescent bacteria – utilize luminol, glow in the dark, symbiosis with deep sea fish (angler fish, shrimp) to help attract a mate and score off predators, attract prey.

Prochlorococcus – smallest known microscopic phytoplankton, marine, numbers are trillion-trillion, responsible for ½ of all global photosynthesis (CO2)

Ice nucleators (IN) – microbes such as Pseudomonas syringae that are found in the upper atmosphere.  They influence weather.  Dust and soot particles act as seed nuclei for the bacteria to attach to them.  Once this happens, the bacteria catalyze ice formation which can then fall to Earth’s surface as rain, sleet or snow.

Snottites – biofilm of chemotrophic bacteria that oxidize hydrogen sulfide.  They are found in caves and produce stalagmite and stalgtite-like columns.  Also etch vertical and horizontal lines in cave walls.

Pathogenicity

Parasite – one that lives at expense of host

  1. Ectoparasite – lives on surface of host
  2. Endoparasite – lives within host

Pathogen – any parasitic organism that produces an infectious disease (ex – cold virus, hook worm)

Pathogenicity – ability of a parasitic organism to cause disease

Final outcome of a host/parasite relationship depends upon:

  1. Virulence of pathogen present – degree or intensity of pathogenicity.
  2. Number of pathogens present
  3. Host degree of resistance

Virulence depends on:

  1. Invasiveness
  2. Infectivity ability to establish a focal point of infection
  3. Pathogenic potential – degree to which the pathogen can cause morbid symptoms

Transport of bacterial pathogen:

  1. Direct contact – cough, sneeze, body contact
  2. Indirect contact – soil, H20, food, vectors – insects, fomites – inanimate objects

Studies of the Human Microbiome (full set of microbial genomes that exist in an organism)

Different body habitats are very different from each other in their microbial communities (mouth, earwax, hair, underarm, toe)

Most diverse – mouth, nose, 231 phyla

Least diverse – stomach, toes, 65 phyla

Large differences in stool and intestinal mucosa – 343 genera with the largest genus being Bacteroides.

Fecal bacterium – anti-inflammatory correlated with pulse and bp

4 largest genera of human microbiomes: Bacteroides, Firmicutes, Actinobacteria, Fecal bacterium

Newborns acquire mother’s vaginal microbiome in natural childbirth, but very little if C-section.  Breast fed have a far more diverse microbiota than formula fed (virtually none).

Identical twins have quite dissimilar microbial communities.

Gut Ecology and c. diff

AAD – antibiotic associated diarrhea – 1st thought to be associated with Staph, but it is due to killing off healthy gut microbes and leaving a very nasty pathogen present – clostridium difficile (bloating, gas, diarrhea, pain lasting for months).

Hard to get good microbes in high numbers to defeat c. diff.  Best way – fecal bacteriotherapy – use host feces (relative), screen it for disease and liquefy, use a feeding tube to ingest.  2-3 days back to normal.

How does our microbiota defend against c. diff?

  1. Impair it directly (attack)
  2. Shape the host immune response
  3. Antimicrobial peptide – Reg III gamma
  4. IgA antibody
  5. Short-chain fatty acids
  6. Occupy space in gut
  7. Colonization defense
  8. Filamentous bacteria stimulate lymphocytes

Salmonella

  1. Use as a possible treatment in prostrate cancer.  1.1 million cases worldwide, mostly in developing countries.  It is the 4th most common in both sexes, 2nd in men, 5th leading cause of cancer death.
  2. Researchers at Swansea University in Wales
  3. They modified the salmonella to render it harmless  and engineered cells to use them as a therapeutic molecule to target cancer cells.  Coupled with Salmonella the molecule delivers the “switching off” gene mechanism to genes in the cancer cells, thus, tumor growth is disrupted.  Also attached to the gene mechanism is an anti-cancer drug which is non-toxic to normal body cells & only a single dose is needed to achieve positive results.

Phase I

Prostrate cancer cells have shrunk in the lab when exposed to the modified bacterium

Phase II

Will be used in clinical application trials.

Helminthes (parasitic worms)

  1. Nematodes – roundworm, pinworm, hookworm
  2. Cestodes – tapeworms
  3. Trematodes – flukes
  4. Filavial worms

Nematodes-In Phylum Aschelminthes, most common intestinal helminth in man.  Diagnose by detection of eggs or larvae in feces, transmission is fecal – oral route (food, water) or skin penetration by larvae (hookworm).  Cylindviral body

Cestodes-Flat, ribbon-shaped body, segmented.  Head or scolex has suckers and hooks for attachment.  No GI tract instead absorb nutrients.  Get from undercooked or raw beef, lamb, pork, or fish.  Dipylidium caninum (dog tapeworm)-get from playing with a dog.  It is the most common.

Trematodes-Phylum Platyhelminthes, bilaterally symmetrical, flat, leaf-shaped, suckers for attachment and sucking.  Most are hermaphrodites (box sex organs in same worm).  Larval stage within the egg, larvae can escape into environment when they can find an intermediate host, then get released as a tail-bearing larvae-cercaria.  Cercaria can penetrate skin, go to the liver and intestines, mature and lay eggs.

Filaviae (dog & cat heart worm)-slender, thread-like nematodes.  Transmitted by bite an arthropod vector (fly, mosquito).  Live in lymphatic system or deep connective tissue of host.  Produce larvae known as microfilaviae.

Wucheria bancrofti & Brugia Malayi – cause lymphatic filiariasis-lymphatic channels become blocked & lymphedema results.

Loa loa – eye worm disease (loiasis)-inhabits deep tissues and can be seen crossing conjunctiva of eye, intense itching, “creeping feeling”.

Onchocerca volvulus-river blindness, major public health problem, worms become encapsulated in fibrous nodules & ocular lesions cause blindness.

Drancunculus medinensis (Guinea worm)-long, slender, soft-bodied worms acquired by drinking contaminated water, exude from any body part with an intense burning.

 

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