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PUBLIC RELEASE DATE:
21-Jan-2008

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Contact: Carrie Patterson
cpatterson@asmusa.org
American Society for Microbiology
@ASMnewsroom

Tips from the Journals of the American Society for Microbiology

Cigarette Smoke May Enhance HPV and Increase Risk of Cervical Cancer

For the first time researchers from Pennsylvania State University College of Medicine suggest a direct interaction between cigarette smoke carcinogens and the human papillomavirus that may lead to increased risk of cervical cancer. They report their findings in the January 2008 issue of the Journal of Virology.

Cervical cancer is the third leading cancer type in women worldwide. Over 90% of the cases presented have been linked to human papillomavirus (HPV). Many women unknowingly carry HPV and the virus naturally regresses on its own over time. HPV will only progress into cervical cancer in a small percentage of women, but past studies have proposed cigarette smoking to be a likely influence.

HPV types 16, 18, and 31 are the most commonly associated with cervical cancer. In the study researchers detected benzo[a]pyrene (BaP), a major carcinogen in cigarette smoke, in the cervical mucus and tested its interaction with HPV. Levels of HPV type 31 increased by 10-fold following exposure to high concentrations of the BaP carcinogen. Levels of HPV types 16 and 18 were also elevated after exposure to BaP.

"Overall, BaP modulation of the HPV life cycle could potentially enhance viral persistence, host tissue carcinogenesis, and permissiveness for cancer progression," say the researchers.

(S. Alam, M.J. Conway, H.S. Chen, C. Meyers. 2008. The cigarette smoke carcinogen benzo[a]pyrene enhances human papillomavirus synthesis. Journal of Virology, 82. 2: 1053-1058.)


Distillers' Grain in Cattle Feed May Contribute to E. coli Infection

A new study suggests that the addition of dried distillers' grain, an ethanol by-product, to cattle feed may contribute to the prevalence of E. coli O157 infection in cattle. The researchers from Kansas State University, Manhattan report their findings in the January 2008 issue of the journal Applied and Environmental Microbiology.

Escherichia coli O157 is a significant food-borne pathogen of which cattle are major reservoirs. Colonization by E. coli O157 in cattle occurs in the gut and is shed in the feces. Diet is considered to be one of the factors influencing the prevalence and shedding of E. coli O157, emphasizing the need to examine dietary components and their impact on the physiological environment of the gut and the survival of E. coli O157.

Distillers' grain is the coproduct that remains following the distillation of ethanol. It may be dehydrated to produce dried distillers' grain (DDG) which is then commonly used as livestock feed. In the study cattle were administered one of three diets including: no dried distillers' grain, steam-flaked corn and 15% corn silage with 0 to 25% dried distillers' grains, or steam-flaked corn with 5% corn silage and 25% dried distillers' grains, after which fecal samples were collected and tested for E. coli O157. Results showed that cattle fed with 25% dried distillers' grains and 5% or 15% silage had higher prevalence of E. coli O157 than cattle fed a diet without dried distillers' grains.

"The results indicate that there is a positive association between dried distillers' grain and E. coli O157 in cattle, and the findings should have important ramifications for food safety," say the researchers.

(M.E. Jacob, J.T. Fox, J.S. Drouillard, D.G. Renter, T.G. Nagaraja. 2008. Effects of dried distillers' grain on fecal prevalence and growth of Escherichia coli O157 in batch culture fermentations from cattle. Applied and Environmental Microbiology, 74. 1: 38-43.)


Amphibian Skin May Offer New Therapy Against Bacterial Infections

Researchers from Italy found that a naturally occurring agent in frog skin may inhibit multi-drug resistant bacterial strains associated with hospital-acquired infections. They report their findings in the January 2008 journal Antimicrobial Agents and Chemotherapy.

Resistance to current antibiotic therapies is on the rise in both hospital and community settings. With some bacterial strains now resistant to every available drug, a return to the preantibiotic era in regard to such infections is cause for great concern. Researchers have identified antimicrobial peptides (AMPs) as one of the most promising candidates for future therapeutic use and they have found amphibian skin to be one of the richest sources of such AMPs.

Nosocomial infections are linked to various drug-resistant bacterial strains and are commonly acquired in a hospital setting as a secondary illness. In the study researchers tested five AMPs (temporins A, B, and G, esculentin 1b, and bombinin H2) from three different frog and toad species (Rana temporaria, Rana esculenta, and Bombina variegata) for antibacterial activity against multi-drug resistant strains often associated with human nosocomial infections. Initial results showed that all the peptides acted as antibacterial agents against the species tested. Further studies found that the temporins were more active against gram-positive bacteria; esculentin 1b produced an antibacterial response within 2 to 20 minutes of exposure, and bombinin H2 displayed similar activity toward all bacterial isolates.

"This peptide is an attractive molecule for use in the development of new compounds for the treatment of infectious diseases," say the researchers.

(M.L. Mangoni, G. Maisetta, M.D. Luca, L.M.H. Gaddi, S. Esin, W. Florio, F.L. Brancatisano, D. Barra, M. Campa, G. Batoni. 2008. Comparative analysis of the bactericidal activities of amphibian peptide analogues against multi-drug-resistant nosocomial bacterial strains. Antimicrobial Agents and Chemotherapy, 52. 1: 85-91.)

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