Computer simulations aid understanding of bacterial resistance against commonly used antibiotics

ScienceDaily (July 22, 2011) — A recent study into the interactions between aminoglycoside antibiotics and their target site in bacteria used computer simulations to elucidate this mechanism and thereby suggest drug modifications.See Also:Health & MedicineInfectious DiseasesCystic FibrosisPlants & AnimalsBacteriaMicrobes and MoreComputers & MathComputer ModelingComputer ScienceReferencePenicillin-like antibioticsBacterial meningitisEndosporeAntiviral drug

In the article, which will be published on July 21st in the open-access journal PLoS Computational Biology, researchers from University of Warsaw, Poland, and University of California San Diego, USA, describe their study of the physical basis of one bacterial resistance mechanism -- mutations of the antibiotic target site, namely RNA of the bacterial ribosome. They performed simulations and observed changes in the interaction between the antibiotic and the target site when different mutations were introduced.

In hospitals throughout the world, aminoglycosidic antibiotics are used to combat even the most severe bacterial infections, being very successful especially against tuberculosis and plague. However, the continuous emergence of resistant bacteria has created an urgent need to improve these antibiotics. Previous experiments on bacteria have shown that specific point mutations in the bacterial ribosomal RNA confer high resistance against aminoglycosides. However, the physico-chemical mechanism underlying this effect has not been known. Using computer simulations the researchers explained how various mutations in this specific RNA fragment influence its dynamics and lead to resistance.

Bacteria have developed other ways of gaining resistance, not just through mutations, and further studies are underway. The authors are now investigating the resistance mechanism by which bacterial enzymes actively modify and neutralize aminoglycosidic antibiotics. These molecular modeling studies together with experiments could help to design even better aminoglycoside derivatives in the future.

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Winning the battle against the Asian tiger mosquito

ScienceDaily (July 22, 2011) — The combination of three complementary measures to eradicate tiger mosquitoes -- avoid having stagnant water, using insecticides to eliminate larvae and adults, and removing rubbish -- reduces more than half the number of tiger mosquitoes, according to research coordinated by researchers at he Universitat Autonoma de Barcelona (UAB) in Spain.See Also:Plants & AnimalsInsects (and Butterflies)Invasive SpeciesPests and ParasitesVirologyWild AnimalsAnimalsReferenceMosquitoBiological pest controlCrane flyDDT

An experimental research carried out in Sant Cugat del Vallès and Rubí, coordinated by researchers from UAB, assessed the efficacy of a combination of strategies to reduce the population of tiger mosquitoes (Aedes albopictus). The research began in February 2008. The research focused on monitoring eggs found in small experimental traps. Researchers observed that for the first time, the number of eggs diminished after applying the measures.

The strategies began with a visit to the affected areas, where owners were informed on prevention measures and told the importance of eliminating any stagnant water accumulating in gardens or patios. The next stage included applying insecticides to plugholes, water storage tanks and drains to eliminate larvae, and removing vegetation from parks and gardens to get rid of adult mosquitoes. The final measure focused on cleaning out all rubbish or debris in the area which could favour the proliferation of the mosquitoes.

Researchers inspected over 3,000 homes and interviewed almost 700 people. To demonstrate the effectiveness of the eradication treatment, researchers monitored the number of eggs deposited in simple traps consisting of small pieces of wood placed in glasses of water. These traps mimic conditions found on tree trucks where mosquitoes originally reproduced in the jungles of Asia.

The research, published in Transactions of the Royal Society of Tropical Medicine and Hygiene, demonstrates for the first time in Europe a substantial reduction in eggs in areas that were treated when compared to the control areas in which no eradication measures were applied. More specifically, the number of eggs in areas where the treatment was applied reduced by more than half.

Native to the jungles of Asian, the Aedes albopictus species was detected for the first time in Spain in Sant Cugat del Vallès the summer of 2004, and from there the mosquitoes began to extend rapidly to other regions of Catalonia. Tiger mosquitoes can be found currently in 119 municipalities and have affected some five million people in all Catalonia.

Although the nuisance caused by these mosquitoes justifies the efforts made to eradicate them, the research was based on the effects the insect has as a vector for the transmission of arbovirus infections, such as dengue fever, yellow fever, etc. The Asian tiger mosquito is the first insect in Spain capable of transmitting these tropical diseases and its arrival represented a paradigm shift. The risk in Europe of this type of disease transmission initially was considered to be low, but possible. In the summer of 2007 there was an outbreak of Chikungunya fever in Italy, with 200 people falling ill due to mosquito bites. Sporadic cases of dengue fever have also been reported in France. Thus, the research offers an intervention model with which to control this insect and apply measures to fight against this public health threat.

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