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RELEASES NEW FOOD SAFETY MANUAL
Food Safety: A Regulator's
Manual For Applying HACCP Principles to Risk-based Retail and Food Service
Inspections and Evaluating Voluntary Food Safety Management System
Food Safety: A Manual for the Voluntary Use of HACCP Principles for Operators
of Food Service and Retail Establishment
Science Forum Commemorates 100 Years of Public Health Science
"A Century of FDA Science: Pioneering the Future of Public Health"
is the theme of the Food and Drug Administration (FDA) 2006 Science Forum,
being held on April 18-20, 2006 at the Washington Convention Center in
The Science Forum features
top agency scientists and clinicians and their counterparts in industry,
academia and other government agencies. The 23 sessions presented at this
year's Science Forum include topics that span the breadth of FDA's regulatory
responsibilities and current innovative approaches to the regulatory mission
of FDA. The sessions include advances in surveillance in medical products,
novel approaches to cancer therapy and monitoring, permanent make-up and
laser removal, and obesity.
On Tuesday, April 18, to kick
off this year's Science Forum, Health and Human Services Secretary Mike
Leavitt and Acting FDA Commissioner, Dr. Andrew von Eschenbach will provide
opening remarks which commemorate the centennial since the agency's founding.
Dr. von Eschenbach will also give a lecture the following day about FDA
for the 21st Century. On Thursday, there will be a session on public preparedness,
moderated by Maggie Glavin, FDA's Associate Commissioner for Regulatory
Affairs. Panelists include Dr. John Agwunobi, HHS Assistant Secretary
for Health; Dr. Jesse Goodman, FDA Director of Center for Biologics Evaluation
Research, and Dr. Anthony Fauci, Director of the National Institute of
Allergy and Infectious Diseases.
FDA is sponsoring a free public
session, "Ask FDA," on April 18, 1:30 p.m.?5:30 p.m. This moderated
session will answer, in plain language, consumer questions about the regulations
of health products that FDA oversees. Attendees will have the opportunity
to ask questions of top agency officials.
For more information on the
2006 Science Forum or to register for the event visit www.fda.gov/scienceforum/.
for more information
not be BSE infectious agents
of Article: http://www.ift.org/news_bin/news/news_home.shtml
4/21/2006-Research from the Veterinary Laboratories Agency in Scotland
suggests that contrary to previous reports, abnormal prions may not be
the infectious agents in transmissible spongiform encephalopathies like
BSE, but in fact be a consequence of prion diseases. For more, see the
Journal of Pathology article abstract:
Plans for Nanotechnology Public Meeting
The Food and
Drug Administration (FDA) will be holding a public meeting in the fall
of this year, designed to gather information about current developments
in uses of nanotechnology materials in FDA regulated products. In a Federal
Register notice displayed today announcing the meeting, FDA asks that
those interested in presenting at or attending the meeting inform the
agency of their interest.
Nanotechnology is described by the National Nanotechnology Initiative
as the understanding and control of matter at dimensions of roughly 1
to 100 nanometers, where unique phenomena enable novel applications. Essentially,
nanotechnology is a branch of science devoted to the design and production
of extremely small matter. Due
to the small size and special properties of nanotechnology materials,
they have great potential for use in a vast array of FDA-regulated products.
These small materials often have physical or chemical properties that
are different than those of their larger counterparts Differences include
altered magnetic properties, altered electrical or optical activity, increased
structural integrity, and enhanced chemical and biological properties.
These differences have the potential to lead to scientific advances. For
example, this technology could be used to create new drug formulations
and routes of delivery to previously inaccessible sites in the body. FDA
is holding this meeting to further its understanding of developments in
nanotechnology and, more specifically, to hear:
About the new types of nanotechnology products under development in the
areas of foods (including dietary supplements), food and color additives,
animal feeds, cosmetics, human and animal drugs and human biologics and
About any specific scientific issues related to the development of these
products relevant to FDA¡¯s regulation of them;Any other issues about which
regulated industry, academia, and the interested public may wish to inform
FDA concerning the use of nanotechnology in FDA-regulated products; and
If there are opportunities for the agency to address hurdles that may
be inhibiting the use of nanotechnology in medical product development.
While the agency is not accepting registrations at this time, it would
appreciate receiving expressions of interest from those intending to attend
or present at the meeting. This information will help FDA prepare and
plan for this meeting. Information can be provided to Poppy Kendall at
Poppy.Kendall@FDA.HHS.GOV, or 301-827-3360. Based on the level of response,
FDA will obtain a venue and structure the meeting to accommodate the audience
and range of topics discussed. Details about the venue, specific date,
time, and registration will be provided in a Federal Register notice closer
to the meeting. You may also look for updates at www.fda.gov/nanotechnology.
04/21. QC / Regulatory Compliance Supervisor - CA-Central
04/21. R&D - QA Manager - HACCP - Louisville, Jeffersonville, KY
04/21. Quality Control Manager - CA-Sacramento
04/21. DIRECTOR OF QUALITY ASSURANCE - Tampa, FL
04/21. Food Safety Specialist - Denver, CO
04/21. Regulatory Affairs Coordinator - Brunswick, GA
04/20. Quality Assurance Technician - City of Industry, CA
04/20. Quality Assurance Technicians - South Milwaukee, WI
04/20. Quality Assurance Technician - Rockland County, NY
04/19. Laboratory Manager - Food Microbiology - Grand Prairie, TX
04/19. HACCP Coordinator - Oakland, IA
04/19. Quality Assurance Manager - Chicago, IL
04/19. Quality Assurance Supervisor - CA-Calabasas Hills
04/19. QA Manager - Evansville, IN; Louisville, KY
04/19. Plant Quality Control Technician - WA-Bellevue
04/19. CA-San Leandro-QA Supervisor
04/18. MN-Rochester-Senior Microbiologist
04/18. TX-Waco-Microbiology Lab Technician
04/18. Regulatory Affairs Coordinator - Brunswick, GA
04/18. Quality Supervisor - Chicago West, IL
04/18. Microbiologist - IL-South Chicago
04/17. Quality Assurance Supervisor - West Jordan, UT
04/17. CO-Denver-Quality Control Specialist
04/17. Microbiology Laboratory Technician - GA-Atlanta
04/17. QA Lab Technician - NJ-Bridgeton
04/17. QA Mgr, Food and Nutr Mfg - Evansville, IN; Louisville, KY
FDA is committed
to ensuring the safety of food and beverages consumed by Americans and
providing timely and factual information when safety questions are raised.
We are issuing this statement today to better describe the steps FDA is
taking in response to reports that benzene has been found in some soft
Benzene, a carcinogen, is found in the environment from natural and man-made
sources. In November 2005, FDA received reports that benzene had been
detected at low levels in some soft drinks containing benzoate salts (an
antimicrobial agent) and ascorbic acid (Vitamin C), particularly under
certain conditions of storage, shelf life and handling.
FDA's Center for Food Safety and Applied Nutrition (CFSAN) initiated a
survey of benzene levels in soft drinks following receipt of the November
2005 reports. This survey indicates that the vast majority of beverages
sampled (including those containing both benzoate salts and ascorbic acid)
contain either no detectable benzene levels or are well below the 5 parts
per billion (ppb) U.S. water standard. The results of this survey, which
will be released in the near future, indicate that the levels of benzene
in these beverages do not pose a safety concern.
FDA's Total Diet Study (TDS) results from 1995 to 2001, as recently reported
by the press, indicated benzene levels in soft drinks that were well above
and inconsistent with CFSAN's more recent survey results. The TDS results
were also well above and inconsistent with levels reported in previous
and current peer-reviewed literature and with hundreds of recent domestic
and international government and beverage industry results. We are working
to determine the source of the differences. As with any data that appear
to be inconsistent, FDA believes it is important to closely examine the
reasons for such differences.
The TDS is an ongoing FDA program that determines levels of various contaminants
and nutrients in a wide variety of foods. The analytical procedures used
in the TDS are designed to detect multiple pesticide residues, industrial
chemicals, and toxic and nutrient elements in many foods, not just benzene
in beverages. Ongoing investigations into the analytical method used by
the TDS suggest that elevated benzene levels can be formed by the procedures
used to analyze beverage samples. This raises major concerns about the
reliability of the TDS data for benzene in beverages and could explain
why these data indicate higher levels of benzene than the levels reported
in the more recent surveys by CFSAN and others, as noted above. We are
continuing our investigation of the TDS data for benzene, and will make
the results available when the investigation is complete.
FDA is also continuing to follow up with companies to ensure that processing
conditions are established that will ensure that benzene formation is
avoided or minimized.
FDA believes that the results of CFSAN's recent survey indicate that the
levels of benzene found in soft drinks do not pose a safety concern.
to debate standards on food additives
By Ahmed ElAmin
Source of Article: http://www.foodproductiondaily.com/
20/04/2006 - Representatives from around the world will meet next week
in the Hague, the Netherlands to hash out a common agreement on international
standards on food additives and contaminants. The five-day meeting forms
part of an ongoing programme to create international food safety standards
under the Codex Alimentarius, a body set up by the Food and Agricultural
Organisation and the World Health Organisation. The standards could eventually
affect the way processors operate worldwide as they become incorporated
into national laws. The meeting relates to the Codex General Standard
for Food Additives (GSFA), which sets forth the conditions and amounts
under which food additives may be used in different food products and
It also relates to a push to lower the amount of contaminants in foods.
Only the food additives listed are permitted for use in foods. Only food
additives that have been evaluated by a joint FAO and WHO expert committee
and found acceptable for use in foods are included in this standard.
Since 1963, Codex has adopted
over 200 commodity standards. Over this time considerable diversity has
arisen in the content and format of the food additive sections among these
standards, according to documents released ahead of the meeting.
Several committees have developed or are developing standards that reference
the GSFA in their food additive sections, for example fermented milks,
and canned citrus fruits. These sometimes different approaches taken by
the committees needs to be unified under the GSFA, the documents state.
"This diversity in approaches, sometimes by the same committee, contributes
to diversity among the food additive sections of Codex commodity standards,"
the documents stated.
In considering revisions to the food additive section of the Codex commodity
standards, the committee proposes to replace the list of food additive
provisions in each commodity standard with text that refers to the appropriate
food category in the GSFA.
The Codex commodity committees will be asked to prepare a section on food
additives in each draft standard. This section would contain a list identifying
the functional classes of food additives which are technologically necessary
for the specified commodity.
Specific additives and maximum levels of use would only be indicated in
cases where exceptional restrictions or permissions are necessary.
Other discussions will centre on the prevention and reduction of aflatoxin
contamination in a wide assortment of nuts, the draft maximum levels for
lead in fish, cadmium, dioxin, chloropropanols, acrylamide and polycyclic
The background documents for the meeting are available here: http://europa.eu.int/comm/food/fs/ifsi/eupositions/ccfac/ccfac_index_en.html
high schoolers exposed to hepatitis A
April 20, 2006
The Health Department says it now appears some Tates Creek High School
students in Fayette county may have been exposed. 26 freshmen tutored
a third grade class at Tates Creek Elementary while a student with Hepatitis
A was there. The Health Department will provide free vaccines for those
freshmen and the teachers and staff who also may have been exposed.
filed over hepatitis-A outbreak
April 20, 2006
WVLT Volunteer TV (TN)
Jacksboro, Campbell County - Concerns over a Hepatitis-A outbreak last
spring in Campbell County are resurfacing, after four people have filed
lawsuits against a Jacksboro restaurant they believe may have helped spread
Whitney Daniel has the details of each lawsuit and explains why these
people are filing suits almost a year later.
Before this, attorneys say, there wasn't ample evidence pinpointing one
particular restaurant as the source of the outbreak. Now, they say Long
John Silver's Seafood Shoppe in Jacksboro is the source.
But still, after a year, the East Tennessee Regional Health Department
says they have not identified a certain restaurant.
The four plaintiffs are each suing the restaurant, its owner, Lenora Morris
and YUM! Brands Incorporated, the company that owns Long John Silver's.
President of the franchise, Dave Carr, gave WVLT this statement:
"Health department officials determined that our Long John Silver's
restaurant was not involved in the hepatitis outbreak... Our assessment
is that (this lawsuit) is baseless. It's unfortunate that we even have
to respond to these claims."
outbreak sickened 163
Source of Article:
Apr 18, 2006 (CIDRAP News) ? The recent outbreak of botulism poisoning
traced to bamboo shoots served at a religious festival in Thailand sickened
163 people, according to a report by the US Centers for Disease Control
and Prevention (CDC).
Of that number, 141 patients had to be hospitalized, and 10 more were
treated as outpatients. A majority experienced abdominal pain, dry mouth,
and/or nausea. Forty-two of the hospitalized patients needed mechanical
ventilation, the CDC said in the Apr 14 issue of Morbidity and Mortality
Thai health officials quickly traced the outbreak to a Mar 14 religious
rite in Nawaimai Village, Pakaluang subdistrict, Baan Luang district of
Nan Province, the report said. Investigators interviewed 145 of the 200
people who had attended the festival about their food intake. The only
food in common was home-canned bamboo shoots, which are often eaten with
chili and shrimp paste.
The bamboo shoots had been produced locally by a women's group, the CDC
wrote. They were processed in large containers that held roughly 26 pounds
each. Most of the 53 cans made in September 2005 were sold locally. No
other outbreaks have been recorded since those cans were produced.
Antitoxin was not available in Thailand, so Thai officials sought help
from several international partners. The United Kingdom (with support
form the World Health Organization) sent 20 vials of heptavalent antitoxin;
CDC sent 50 vials of bivalent antitoxin; and the National Institute of
Infectious Diseases in Japan sent 23 vials of trivalent antitoxin. A Canadian
company sold Thailand an additional 10 vials of bivalent antitoxin.
By Apr 10, only 25 patients still remained in the hospital, 9 of them
on respirators, the CDC noted. None of the 163 patients died. A study
assessing the outcomes of some of the cases is ongoing, the agency noted.
The report said the outbreak occurred 8 years after a smaller botulism
outbreak that also was associated with home-canned bamboo shoots. Following
that episode, information on safe canning was disseminated throughout
"This recurrence 8 years later indicates the importance of long-term
follow up and continuous inspection and assurance of the quality of food
canning," the CDC said.
Love: Grandmother tirelessly cares for E-coli stricken child
April 20, 2006
Palatka Daily News (Florida)
INTERLACHEN -- Five years ago, Nancy Doane, 55, adopted her granddaughter,
Christen Doane, from foster care.
Christen was once a robust and cheerful baby. Now she is a paraplegic,
confined to a wheelchair and dependent on a feeding tube for sustenance.
The story says that when Christen was 17 months old, her mother, Juanita
Boyd, took her for a quick dinner at a local fast food restaurant, hoping
to get back home in time to help her three older children with their homework.
She ended up admitting her only daughter to Shands at the University of
Florida for three months. Christen was diagnosed with Escherichia coli
O157-H7 bacterial disease. While she was in the hospital she suffered
from a stroke, which Doane believes was the result of too much medication.
The stroke left little Christen severely disabled. Christen was taken
from her mother in 1998, when the Department of Children and Families
deemed Boyd an unfit mother.
Boyd has three boys and she said DCF thought she was not fit to take care
of four children, especially one who is handicapped.
reduces pathogens in meat
Source of Article: http://www.ift.org/news_bin/news/news_home.shtml
4/21/2006-A mixture of lactic acid bacteria shown to reduce foodborne
pathogens such as Salmonella and E. coli O157:H7 in processed beef and
poultry by as much as 99.99 percent has passed GRAS (or generally recognized
as safe) status review by the Food and Drug Administration.
The mixture, to be sold under the name Bovamine Meat Cultures ¢â, is one
of the few post-production treatments available that protects meat and
poultry during long-term storage. Administered during the processing phase,
it works with other interventions throughout the beef production chain
to provide an added layer of protection for consumers.
The treatment was developed through Texas Tech University and is available
through Indianapolis-based Nutrition Physiology Corp. Research was funded
by the Beef Checkoff Program, the Texas Beef Council and Nutrition Physiology
¡°Illness rates associated with E. coli O157:H7 have declined steadily
over the past ten years. Each sector of the beef production chain has
developed and implemented best practices aimed at reducing foodborne bacteria
and this lactic acid mixture is another great example,¡± said Mike Engler,
Ph.D., Joint Beef Safety Research Committee chairman and Texas beef producer.
¡°It is through the efforts of a united industry, sharing these data and
best practices, that we have been able to attack illnesses attributed
to pathogens such as E. coli O157:H7 and reduce their occurrence.¡±
The development of the mixture of lactic acid bacteria was led by Dr.
Mindy Brashears, associate professor and director of the International
Center for Food Industry Excellence at Texas Tech. Tested under conditions
simulating meat storage and transfer to and from supermarkets, the product
was found to reduce Salmonella by 99.9 percent and E. coli O157:H7 by
99 percent. In addition, the cultures were put through a battery of both
subjective and objective taste tests and were shown to have no impact
¡°Lactic acid bacteria are considered good bacteria in that they have a
lot of benefits,¡± Brashears said. ¡°They are used to make several products
like cheese, yogurt and sausages. They have a place in nature and they
compete with other bacteria by producing compounds that kill the other
bacteria. That is where the concept of using these bacteria to actually
reduce foodborne pathogens came from. It is not a new concept, but some
of the applications we have developed are unique.¡±
Meat and poultry products containing this mixture will be labeled to reflect
the lactic acid cultures used to reduce foodborne pathogens. A link to
the FDA¡¯s letter can be found at: http://www.cfsan.fda.gov/~rdb/opa-g171.html
sterilisers designed for bakery equipment
By Ahmed ElAmin
Source of Article: http://www.foodproductiondaily.com/
18/04/2006 - A new series of
carbon infrared emitters can help bakeries speed up the sterilisation
of tins, trays and equipment, according to the manufacturer. Infrared
disinfection allows plants to use controlled heat targeted at key areas.
In bakeries, the first priority is the elimination of mould growth. Radiation
emitters direct their heat where it is required and for only as long as
needed. The system prevents equipment as well as the baked goods from
heat damage, while disinfecting areas. The use of carbon infrared radiation
allows heat to penetrate into porous materials or multiple spore layers,
Heraeus Noblelight said about its new series of emitters. The machines
can be used for eliminating moulds from cake tins, trays and equipment.
The carbon infrared emitters use radiation in the medium wavelength region
with a high power density. The company cited a study from the Bremerhaven
Institute for Food and Bio-processing Technology, which studied the use
of the process for six months. The research concluded that infrared radiation
can help large bakeries to comply with hygiene standards.
The research showed that, with
carbon infrared emitters there is sufficient disinfection of baking trays
between 130¨¬C and 140¨¬C in less than 30 seconds. The spore reduction is
achieved between 120¨¬C and 160¨¬C within 10 to 30 seconds, depending on
the emitter power, the wetness of the tray and the desired speed of operation.
"The study showed that the instruments destroyed germs and bacteria
safely and in a practicable way," Heraeus Noblelight stated. "Even
thick layers of germs, porous surfaces or dust particles did not hamper
the process of sterilisation due to the deep penetrating action of the
radiation." Muslin tray cloths can also be dried using infrared.
This is important when a bakery plant is operated round the clock and
it is not possible to carry out drying during the idle phases, the company
"By carrying out this
infrared drying in parallel with the disinfection the operating life of
the muslin cloths is significantly extended, allowing greater intervals
between replacements," Heraeus Noblelight claimed. The devices have
power densities up to 150 kW/m©÷ and a response time of seconds. "The
fast response times allow for good controllability so that heat is applied
for only as long as necessary, drying and disinfection cycles can be programmed
and, if there is inadvertent stoppage of the conveyor belt, overheating
of the baked goods or the machinery itself is prevented," the company
stated. The compact construction of an infrared emitter system, makes
it possible for plants to retro-fit infrared disinfection into existing
lines, the company claimed.
Carbon infrared technology
is also used by bakeries to achieve a browning effect on their products.
The technology is suitable for evaporating water from products at a very
high power intensity. This ensures that the surface of the food product
rapidly achieves a sufficient temperature to drive away local moisture
and then causes browning without heating the body of the product. The
Bremerhaven Institute is a test centre that performs research and development
services for the private sector. The institute focuses on the bakery sector.
Journal of Food Safety (Current Issue)
Vol 8. 23-29
Development of Process for Preparation of Pure & Blended Kinnow Wine
without Debittering Kinnow Mandarin Juice
Vol 8. 19-23
Aspergillus, Health Implication & Recommendations for Public Health
Vol 8. 14-18
An Observational Study of The Awareness of Food Safety Practices in Households
Vol 8. 7-13
Antibacterial activity of oregano tea and a commercial oregano water against
Escherichia coli O157:H7, Listeria monocytogenes 4b, Staphylococcus aureus
and Yersinia enterocolitica 03.
Vol 8. 3-6
Safety and quality practices in closed-house poultry production in Thailand:
2004-avian influenza outbreak
Vol 8. 1-2
The introduction of the Japanese Carpet Shell in coastal lagoon systems
of the Algarve (south Portugal):
a food safety concern
Protection of Food from Adulterants/Proper Labeling, Storage- VIDEO
Dr. Lori Pivarnik
University of Rhode Island
Click here for Windows Media Streaming Versions
Prevention of Cross-Contamination
Dr. Thomas Rippen
Seafood Technology Specialist with the Maryland Sea Grant Program
the University of Maryland Eastern Shore
Click here for Windows Media Streaming Versions (Recommended)
or click here for HTTP Server
Profile Extension Instructions on Food Defense Plans for Meat and Poultry
Lactic acid bacteria treatment reduces pathogens in meat
Managing Food Safety: A Regulator's Manual For Applying HACCP Principles
Manual for the Voluntary Use of HACCP Principles for Operators of Food
Service and Retail Establishments
Manual for the Voluntary Use of HACCP Principles for Operators of Food
Service and Retail Establishments (PDF)
Meeting of the Codex Committee on methods of analysis and sampling
Meeting of the Codex Committee on residues of veterinary drugs in foods
AVAILABILITY OF CLEANING FREQUENCY QUESTIONS AND ANSWERS
Statement By Agriculture Secretary Mike Johanns Regarding Canada's Fifth
Case Of BSE
GIPSA Updates Alfatoxin Handbook
FDA¡¯s 2006 Science Forum Commemorates 100 Years of Public Health Science
FDA Announces Plans for Nanotechnology Public Meeting
Constituent Update: Apr 14, 2006
Benzene in Soft Drinks
Availability of Revised Versions of Guidance Materials
JOHANNS SIGNS AGREEMENT WITH CHINA ON FOOD SAFETY AND PLANT AND ANIMAL
Interstate shellfish dealers certificate
Safe and Suitable Ingredients Used in the Production of Meat and Poultry
FSIS Reminds Consumers to Properly Handle and Cook Ground Beef Products
FSIS Issues Amendment to Safe Ingredients List
Design Antimicrobial, Technique to Watch It
Source of Article: http://www.newswise.com/articles/view/519808/?sc=rssn
Researchers have designed a new molecule that selectively slashes bacterial
cell membranes, leaving the microbes to leak and die. Such compounds could
lead to new topical or intravenous antibiotics, or to self-sterilizing
materials ranging from countertops to surgical gowns.
UMass Amherst scientists can follow the action of a potential antibiotic
as it slices into a synthetic bacterial membrane made of phospholipids.
The researchers use sum frequency generation (SFG) vibrational spectroscopy,
a technique that exploits lasers.
Newswise ? In the continuing battle against drug-resistant bacteria, scientists
from the University of Massachusetts Amherst are adding new weapons to
the arsenal. Gregory Tew and his colleagues have designed a molecule that
selectively slashes bacterial cell membranes, leaving the microbes to
leak and die. Such compounds could lead to new topical or intravenous
antibiotics, or to self-sterilizing materials ranging from countertops
to surgical gowns. The findings are reported in today¡¯s (April 21) issue
of the journal Chemistry & Biology.
The research follows work by
Tew¡¯s lab and colleagues led by Zhan Chen at the University of Michigan
whereby the scientists developed a technique that lets them watch such
an antimicrobial knife in action. By following the interaction of a promising
antimicrobial molecule with a membrane?in real-time and with relevant
quantities?scientists should be able to design more effective antibiotics.
The technique was reported in the Journal of the American Chemical Society
Antibiotic resistance has been called one of the world¡¯s most pressing
health problems. As scientists seek new compounds for fighting bacterial
infections some are turning to the snippets of protein that make up the
body¡¯s first line of defense against invading pathogens. Using the structure
and conformations of these natural molecules as inspiration, Tew¡¯s team
has been designing synthetic antimicrobials in the lab.
Because a molecule that looks well and good on paper might not keep its
desired properties once built, Tew also tests his designs using X-ray
crystallography and computer calculations. By getting a read on the molecule¡¯s
¡°energy landscape,¡± the researchers can evaluate whether a shape that
confers desired slicing powers on paper will maintain that shape once
The newly designed antimicrobial
compound has a super-stiff backbone, an important structural decision,
says Tew, noting that previously researchers focused on the arrangement
of the side-chains that are attached to the backbone. The stiff spine
yields a compound that has charges distributed in such a way that it is
attracted to the water-lipid interface of the bacterial membrane, says
To test its ability to distinguish
friend from foe, the researchers pitted the new compound against microbes
such as E. coli and Staphylococcus aureus?the bacterium whose resistant
strains plague hospitals?and against human red blood cells. The tests
revealed that the new design is indeed both lethal and selective. While
it slashed bacterial membranes with zeal, the compound left the human
blood cells alone.
Many antibiotics attack a bacterium¡¯s
membrane-making machinery, not the membrane itself, says Tew. By taking
a hint from nature and mimicking a class of molecules that goes right
for the membrane, he hopes bacteria won¡¯t be able to simply tweak their
machinery to evade it. The new molecule has shown no propensity for inducing
resistance compared to current antibiotics that attack bacteria through
more classical routes, he says.
Gaining a better understanding
of how these antibiotics work against the membrane will be essential to
further improvements, says Tew. So he and Chen used sum frequency generation
(SFG) vibrational spectroscopy?a technique that uses lasers and is typically
employed by chemists for identifying molecules at surfaces?to further
explore the antibiotic-membrane interaction. Tew and Chen have harnessed
SFG to explore which molecules pack the strongest antimicrobial punch
and how this punch is delivered at the molecular level.
The scientists created a synthetic
cell membrane?a bilayer of phospholipid molecules typical of a bacterial
cell membrane?and then set the membrane below a clear prism in a trough
of water. The researcher then directed two lasers through the prism making
the membrane molecules vibrate at specific frequencies. When the researchers
injected the antimicrobial compound into the water trough, it sliced into
the membrane?a move the researchers monitored via the change in the vibrational
Using SFG lets the researchers
watch a potential antibiotic at work?and at concentrations that are meaningful,
says Tew. By combining the SFG data with lab experiments on a compound¡¯s
bacteria-inhibiting abilities and tests that look at how much cell leakage
occurs, researchers will be able to learn more about the molecular interactions
governing this antimicrobial activity, he says.
¡°Being able to see how these
molecules interact with the membrane at the molecular level in real-time
will prove invaluable,¡± says Tew. ¡°This will let us build much better
models of how these novel antibiotics interact with membranes?if we understand
that, we can build drugs that are more effective and less toxic.¡±