Tips from the journals of the American Society for Microbiology

New Non-Invasive Vaccine Strategy May Offer Protection Against Tetanus and Anthrax

A new vaccine strategy using genetically engineered bacteria topically applied to the skin elicits an immune response to both tetanus and anthrax in animals say researchers from Vaxin Inc., Birmingham, Alabama. They report their findings in the June 2006 issue of the journal Infection and Immunity.

The new vaccine strategy described in this study consists of a topically applied vaccine containing live Escherichia coli bacteria that are genetically engineered to produce proteins associated with the bacteria that cause anthrax and tetanus. These compounds can be administered by nonmedical personnel. Past studies have shown the outer layer of the skin to be more immunocompetent than deep tissue and experts believe that self-applied painless vaccines will further increase the compliance rate.

In the study mice were administered a topical E. coli vectored vaccine and then challenged with tetanus cells and anthrax spores. Ninety percent of the vaccinated mice infected with tetanus survived, those that didn't receive the vaccine died within five days. Of the mice vaccinated and challenged with anthrax, only 44% survived, but when additional E. coli particles were added, the survival rate increased to 55%.

"The nonreplicating E. coli vector overproducing an exogenous immunogen may foster the development of a new generation of vaccines that can be manufactured rapidly and administered noninvasively in a wide variety of disease settings," say the researchers.

(J. Zhang, Z. Shi, F. Kong, E. Jex, Z. Huang, J.M. Watt, K.R. Van Kampen, D.C. Tang. 2006. Topical application of Escherichia coli-vectored vaccine as a simple method for eliciting protective immunity. Infection and Immunity, 74. 6: 3607-3617.)

Copper May Aid in Food Safety

A new study suggests that the use of cast copper alloys during food processing may help prevent cross-contamination of E. coli better than stainless steel say researchers from the University of Southampton, United Kingdom and Copper Development Association Inc., New York. Their findings appear in the June 2006 issue of the journal Applied and Environmental Microbiology.

Escherichia coli O157 is one of the most serious food-borne pathogens worldwide causing physical effects ranging from diarrhea to hemorrhagic colitis. Cattle is a major reservoir of E. coli O157, therefore outbreaks are primarily associated with consumption of undercooked ground beef. Cross-contamination of infected meat with points of contact during processing makes it extremely difficult to maintain. Currently, stainless steel has been the metal of choice for food preparation, however, studies have shown that even with consistent cleaning and sanitation procedures bacteria can remain viable.

In the study cast copper alloys (a mixture of metals containing varying degrees of copper) and stainless steel were exposed to E. coli, some mixed with beef juice, some without, and incubated at either 22 degrees Celsius or 4 degrees Celsius for up to six hours. Results showed that three copper alloys not exposed to beef juice completely killed E. coli when stored at 22 degrees Celsius and only the alloys containing high quantities of copper (85% or more) significantly reduced E. coli at 4 degrees Celsius. With beef juice, alloys consisting of 93% or more copper greatly reduced E. coli at 4 degrees Celsius, while only one alloy (containing 95% copper) completely killed the bacterium at 22 degrees. No significant reduction in cell numbers was reported for stainless steel.

"These results clearly demonstrate the antimicrobial properties of cast copper alloys with regard to E. coli O157, and consequently these alloys have the potential to aid in food safety," say the researchers.

(J.O. Noyce, H. Michels, C.W. Keevil. 2006. Use of copper cast alloys to control Escherichia coli O157 cross-contamination during food processing. Applied and Environmental Microbiology, 72. 6: 4239-4244.)

Houseflies Collected in Fast Food Restaurants Found to Carry Antibiotic Resistant Bacteria

Houseflies in food-handling and serving facilities carry and may have the capacity to transfer antibiotic-resistant and potentially virulent bacteria say researchers Kansas State University. They report their findings in the June 2006 issue of the journal Applied and Environmental Microbiology.

Multi-drug resistance is a serious problem plaguing the world today as the number of antibiotics effective at treating human infections continues to decline. Although it is not yet well understood, preliminary research has indicated a connection between antibiotic resistance and food of animal origin. Experts are now examining the role that insects that develop in decaying organic material (specifically manure) may play in transmitting antibiotic resistant bacteria to residential settings.

Enterococci are commonly found in animal and human digestive tracts and are known for their frequent multi-antibiotic resistance. Two of the 26 species, Enterococcus faecalis and Enterococcus faecium are responsible for the majority of human infections. In the study the digestive tracts of 260 houseflies collected from five fast food restaurants were tested for enteroccoci and characterized. Ninety-seven percent tested positive for the bacteria with E. faecalis identified in the majority of the isolates (88.2%). E. faecalis was found to carry virulence genes and have varying percentages of resistance to tetracycline, erythromycin, streptomycin, ciproflaxin and kanamycin. E. faecium showed up at a rate of 6.8%.

"This study showed that houseflies in food-handling and serving facilities carry antibiotic-resistant and potentially virulent enterococci that have the capacity for horizontal transfer of antibiotic resistance genes to other bacteria," say the researchers.

(L. Macovei, L. Zurek. 2006. Ecology of antibiotic resistance genes: characterization of enterococci from houseflies collected in food settings. Applied and Environmental Microbiology, 72. 6: 4028-4035.)


Last reviewed: By John M. Grohol, Psy.D. on 30 Apr 2016
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