Escherichia coli

8 12 2006

ecoli.jpg

The latest food poisoning of E.Coli makes one wonder: Just how safe is our food supply? Are the increased frequency of incidents an indicator of sloppy food handling, processing, and transport, or are we seeing the work of some group or entity testing our ability to detect pathogens in our food supply?

Contaminating foods with E. Coli is extraordinarily easy. Just culture it in an easily made bilogical medium known as Agar. Agar is typically sold as packaged strips of washed and dried seaweed, or in powdered form. Combine the E Coli culture with liquid, and spray a field with a hand pump, or toss a jar of it onto a bin of it during harvesting or processing.

The culprit here is a speciifc strain of Escherichia coli (usually abbreviated to E. coli, coli is Latin for “of the colon”) discovered by Theodor Escherich, a German pediatrician and bacteriologist, is one of the main species of bacteria that live in the lower intestines of mammals, known as gut flora. Specimens have also been located on the edge of hot springs. Presence in surface water is a common indicator of fecal contamination. It belongs among the Enterobacteriaceae, and is commonly used as a model organism for bacteria in general. One of the root words of the family’s scientific name, “enteric”, refers to the intestine, and is often used synonymously with “fecal”.

The number of individual E. coli bacteria in the feces that a human excretes in one day averages between 100 billion and 10 trillion. All the different kinds of fecal coli bacteria, and all the very similar bacteria that live in the ground (in soil or decaying plants, of which the most common is Enterobacter aerogenes), are grouped together under the name coliform bacteria.

E.coli O157:H7 is the strain that cuases illness in humans and can be fatal, as has been the case this week with scallions served in food at Taco Bell Restaurants.

Escherichia coli O157:H7 is a leading cause of foodborne illness. Based on a 1999 estimate, 73,000 cases of infection and 61 deaths occur in the United States each year. In the ten CDC Foodborne Diseases Active Surveillance Network (FoodNet) sites (which represent 15% of the US population), there was a 29% decline in E. coli O157:H7 infection since 1996-98.

Infection with E. coli often leads to bloody diarrhea, and occasionally to kidney failure. People can become infected with E.coli O157:H7 in a variety of ways. Though most illness has been associated with eating undercooked, contaminated ground beef, people have also become ill from eating contaminated bean sprouts or fresh leafy vegetables such as lettuce and spinach. Person-to-person contact in families and child care centers is also a known mode of transmission. In addition, infection can occur after drinking raw milk and after swimming in or drinking sewage-contaminated water.

Consumers can prevent E. coli O157:H7 infection by thoroughly cooking ground beef, avoiding unpasteurized milk, and by washing hands carefully before preparing or eating food. Fruits and vegetables should be washed well, but washing may not remove all contamination. Public service announcements on television, radio, or in the newspapers will advise you which foods to avoid in the event of an outbreak.

Surprisingly, a common household spice, cinnamon, seems to kill this strain of E.Coli. When cinnamon is in, Escherichia coli O157:H7 is out. That’s what researchers at Kansas State University discovered in laboratory tests with cinnamon and apple juice heavily tainted with the bacteria. Presented at the Institute of Food Technologists’ 1999 Annual Meeting in Chicago on July 27, the study findings revealed that cinnamon is a lethal weapon against E. coli O157:H7 and may be able to help control it in unpasteurized juices.

Lead researcher Erdogan Ceylan, M.S., reported that in apple juice samples inoculated with about one million E. coli O157:H7 bacteria, about one teaspoon (0.3 percent) of cinnamon killed 99.5 percent of the bacteria in three days at room temperature (25 C). When the same amount of cinnamon was combined with either 0.1 percent sodium benzoate or potassium sorbate, preservatives approved by the Food and Drug Administration, the E. coli were knocked out to an undetectable level.

Let’s hope the active agent in cinnamon can be isolated and put twoards protecting our food supply.

In the meatime here is some information from the Center for Disiease Control

How is E. coli O157:H7 infection diagnosed?
Infection with E. coli O157:H7 is diagnosed by detecting the bacterium in the stool. About one-third of laboratories that culture stool still do not test for E. coli O157:H7, so it is important to request that the stool specimen be tested on sorbitol-MacConkey (SMAC) agar for this organism. All persons who suddenly have diarrhea with blood should get their stool tested for E. coli O157:H7.

How is the illness treated?
Most people recover without antibiotics or other specific treatment within 5 to 10 days. Antibiotics should not be used to treat this infection. There is no evidence that antibiotics improve the course of disease, and it is thought that treatment with some antibiotics could lead to kidney complications. Antidiarrheal agents, such as loperamide (Imodium®), should also be avoided.

In some people, E. coli O157:H7 infection can cause a complication called hemolytic uremic syndrome (HUS), a life-threatening condition that is usually treated in an intensive care unit. Blood transfusions and kidney dialysis are often required. With intensive care, the death rate for hemolytic uremic syndrome is 3%-5%.

What are the long-term consequences of infection?
Persons who only have diarrhea usually recover completely.

A small proportion of persons with hemolytic uremic syndrome (HUS) have immediate complications with lifelong implications, such as blindness, paralysis, persistent kidney failure, and the effects of having part of their bowel removed. Many persons with hemolytic uremic syndrome have mild abnormalities in kidney function many years later.





Yottawatts

8 12 2006

meter_reading.jpg

Ok the first thing that went through my mind when I saw the word Yottawatts was that episode of Seinfeld where Elaine uses the phrase…yadda, yadda, yadda…

But its actually about powers of ten and electrical power (watts). I was researching the amount of solar insolation the earth receives from the sun (174 Petawatts) and ran across this page in WikiPedia full of variations on my namesake.

By the way, Petawatts has nothing to do with my disdain for the sometimes crazy tactics of the animal rights group.

So have a few watts on me:

Yoctowatt (10-24 watt)

Zeptowatt (10-21 watt)

Attowatt (10-18 watt)

Femtowatt (10-15 watt)

  • 2.5 fW - Tech: minimum discernible signal at the antenna terminal
    of a good FM radio
    receiver

  • 10 fW (-110 dBm) - Tech: approximate lower limit of power reception
    on digital spread-spectrum cell phones

Picowatt (10-12 watt)

  • 1 pW - BioMed: average power consumption of a human cell
  • 2.5 pW - BioMed: Sound intensity per square centimeter for average
    human threshold of hearing at 1000 Hz; 1 phon
    or 0 dB SPL

  • 150 pW - BioMed: Power entering a human eye from a 100 watt lamp 1
    km away

Nanowatt (10-9 watt)

  • 2-15nW - Tech: Power consumption of some PIC Microcontroller chips
    such as the PIC12F683 when in "sleep" mode. (actual consumption
    when sleeping depends on voltage supply used, see data sheet, Electrical
    Characteristics section).

Microwatt (10-6 watt)

Milliwatt (10-3 watt)

  • 5 mW - Tech: laser in a CD-ROM
    drive

  • 5-10 mW - Tech: laser in a DVD
    player

  • 100 mW - Tech: laser in a CD-R
    drive

Watt

1 Watt = 1 amp x
1 volt of electrical power

  • 5 W - Legal: maximum power output of a CB
    or hand-held radio transmitter

  • 20-40 W - BioMed: approximate power consumption of the human brain
  • 30-40 W - Tech: the power of the typical household tube light
  • 60 W - Tech: the power of the typical household light
    bulb

  • 82 W - Tech: peak power consumption of Pentium
    4
    CPU

  • 100 W - BioMed: approximate average power used by the human
    body

  • 120 W - Tech: power output of 1 m2 solar
    panel
    in full sunlight

  • 253 W (2,215 kWh/year)
    - Geo: per capita average power use of the world in 2001

  • 290 W - Units: approximately 1000 BTU/hour
  • 300-400 W - Tech: typical PC
    power supply

  • 400 W - Tech: legal limit of power output of an amateur
    radio
    station in the United
    Kingdom

  • 500 W - BioMed: power output of a person working hard physically
  • 745.7 W - Units: 1 horsepower
  • 750 W - Astro: the amount of sunshine falling on a square metre of
    the Earth’s surface on a clear day

  • 900 W - BioMed: power output of a healthy human (non-athlete)
    averaged over the first 6s of a 30s cycle sprint. [1]

Kilowatt (103 watt)

  • 1.366 kW - Astro: power received from the Sun
    at the Earth’s
    orbit by one
    square metre

  • 1.39 kW (12.2 MWh/year) - Geo: per capita average power use in the U.S.
    in 2003

  • 1.5 kW - Tech: legal limit of power output of an amateur
    radio
    station in the United
    States

  • up to 2 kW - BioMed: approximate short time power output of
    sprinting professional cyclists

  • 1 kW to 2 kW - Tech: heat output of a domestic electric kettle.
  • 3.3-6.6 kW - Eco: average photosynthetic
    power output per square
    kilometer
    of ocean
    [2]

  • 30 kW - power generated by the four motors of GEN H-4 one man helicopter
  • 16-32 kW - Eco: average photosynthetic power output per square
    kilometer of land
    [3]

  • 50 kW to 100 kW - Tech: ERP
    of clear
    channel
    AM

  • 40 kW to 200 kW - Tech: approximate range of power output of
    typical automobiles

  • 167 kW - Tech: power consumption of UNIVAC
    1
    computer

  • 250 kW - Tech: highest allowed ERP
    for an FM
    band
    radio
    station
    in the United
    States
    .

  • 250 kW to 800 kW - Tech: approximate range of power output of ‘Supercars

Megawatt
(106 watt)

The productive capacity of electrical generators operated by utility
companies is often measured in MW. Few things can sustain the transfer or
consumption of energy on this scale; some of these events or entities include:
lightning strikes, naval craft (such as aircraft
carriers
and submarines),
engineering hardware, and some scientific research equipment (such as the supercollider
and large lasers).

For reference, about 10,000 100-watt lightbulbs or 5,000 computer systems
would be needed to draw 1 megawatt. Also, 1 MW equals approximately 1341 horsepower.
Modern high-powered diesel-electric
railroad locomotives
typically have a peak power output of 3–5 MW, whereas a typical modern nuclear
power plant
produces on the order of 500–2000 MW peak output.

Gigawatt (109 watt)

Terawatt (1012 watt)

  • 1.7 TW - Geo: average electrical power consumption of the world in 2001
  • 3.327 TW - Geo: average total (gas, electricity, etc) power
    consumption of the U.S.
    in 2001

  • 13.5 TW - Geo: average total power consumption of the human world
    in 2001

  • 44 TW - Geo: average total heat flux from earth’s interior (See
    figure in http://physicsweb.org/articles/news/9/7/16/1)

  • 75 TW - Eco: based on global net
    primary production
    (= biomass
    production) via photosynthesis

  • 50 to 200 TW - Weather: rate of heat energy release by a hurricane
  • In "Star Trek: The Next Generation", the warp core of the
    fictitious Enterprise-D was able to produce a maximum power output into the
    Terawatt range.

Petawatt (1015 watt)

Exawatt (1018 watt)

  • 1 EW - Astro: Approximate power generated between the surfaces of
    Jupiter and its moon Io due to Jupiter’s tremendous magnetic field.

Zettawatt (1021 watt)

Yottawatt (1024 watt)

  • 5.3 YW - Tech: Power produced by the Tsar
    Bomba
    fusion bomb, the most powerful device ever made

  • 386 YW - Astro: Luminosity
    of the Sun

Greater than Yottawatt