Posts Tagged “escherichia coli”

Infections in the teeth implants are dreaded, running a high risk of potentially affecting the jaw bones. It is actually not that uncommon. The overall number of performed teeth implantations in the US and Europe has doubled over the last decade, yet studies show that 10 percent of the implants are associated with problems, usually in the first year directly after the operation. To prevent any further deterioration, the implants sometimes have to be removed.

New methods are now being developed by researchers in the University of Zurich to keep inflammation-causing bacteria at bay. In their PLoS ONE article, they present their materials and methods, which have successfully eliminated 99% of the microbes after a 15-minute electrical treatment.

Conventional treatment methods of this sort of inflammation depend on the utilization of topical antibiotics, which is surely a burden for the patient. The aim of the study was to develop a non-invasive approach to efficiently fight off the bacteria, or, as the researchers phrase it in their paper, to develop “an in-situ decontamination of the dental implants”.

The whole idea is based on the process of water treatment, where sterile water is produced through electrolysis. In order to simulate the conditions in the jaw, an Escherichia coli bacterial film was coated onto the titanium implants, which were impregnated in a gelatinous preparation. In the experimental design, one implant functioned as the cathode and the other as the anode. The implants were subjected to a 15-minute-long electrical treatment, of an intensity ranging between 0 and 10 Milliampere. This artificially generated electrical field caused the hydroxyl ions of the water molecules to migrate to the cathode, and thus raising the pH. A color change of the indicators, used in the gelatin, prove that an alkaline environment predominates at the cathode. On the other hand, the pH value drops at the anode, forming an acidic milieu.

The numerous experimental models with various electrical intensities show that in cases, where an acidic ambience was produced around the implants, 99% of the bacteria died off after a 15-minute treatment. Therefore, the patient implants in the future will take up the role of the anode. A clip at the lip will be used as a cathode.

What at first glance might seem as a torture mechanism is in reality completely harmless. The minute amount of Milliampere, which is sufficient to conquer the bacteria, is hardly even perceived by the patient and would tops cause a mild muscle twitching.




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So, we thought the worse was over; we thought we are done fighting the bad guys, HIV, SARS and H1N1A, but now it seems that a new menace is eminent. Our chaotic and rather foolish use of antibiotics have created this unknown danger that could add a new chapter to the history of medicine and fighting infectious diseases. This danger is called New Delhi metallo Beta-Lactamase -1, AKA NDM-1

Meet the Bug

In December 2009, a super villain appeared on the scene; he’s violent, resistant and determined to do as much damage as he could. Our super villain is the NDM-1 (New Delhi metallo beta lactamase – 1), a newly emerging beta-lactam resistance enzyme including carbapenems, which are one of few alternatives used for antibiotic-resistant bacterial infections. The NDM-1 gene is classified as a Carbapenemases . The enzyme is named after the city in which it first appeared, New Delhi, the Indian capital. In December 2009, a Swedish patient in India acquired an antibiotic resistant infection. Being unsuccessfully treated in India, the patient was further transferred to Sweden. The carbapenem-resistant Klebsiella pneumoniae was identified carrying the novel NDM-1 gene. A later study in India found that carbapenem-resistant strains from patients in India carried the NDM-1.

The Spread

In May 2010, an E. coli expressing the NDM-1 gene was isolated from a patient in the UK, the patient was of Indian origin and had visited India 18 months ago where he had been undergoing dialysis. According to CDC Morbidity and Mortality Weekly Report (MMWR) , as of June 2010, three Enterobacteriaceae isolates carrying the NDM-1 gene were discovered in the U.S., which were E. coli, Klebsiella pneumoniae, and Enterobacter cloacae, NDM-1 provided the three isolates with resistance to all antibiotics except for Aztreonam. Fortunately to the bacteria but unfortunately to our patient, the isolates conferred resistance even to Aztreonam by different mechanism other than the NDM-1, and the MMWR established that all the three U.S. isolates were related to patients who had medical care in India.

Furthermore, a team in India in July 2010, reported cases of Acinetobacter baumannii carrying the NDM-1 in India. A recent study by a multinational team published in “The Lancet Infectious Diseases, September 2010” reported that the isolation of 44 isolates with NDM-1 in Chennai, 26 in Haryana, 37 in the UK, and 73 in other sites in India and Pakistan. NDM-1 was mostly found among E. coli (36) and Klebsiella pneumoniae (111), which were highly resistant to all antibiotics. Luckily, all the studies have confirmed that all NDM-1 isolates were susceptible to the antibiotics tigecycline (the FDA-approved glycylcycline antibiotic developed by Francis Tally and marketed by Wyeth under the brand name Tygacil®), and colistin (polymyxin E antibiotic, which causes nephrotoxicity and neurotoxicity at high dose IV). Some unconfirmed reports indicate the NDM-1 appearing in Canada and Japan earlier this month (Sep 2010).

First Victim

In June 2010, patient zero –the first reported death– was a Belgian man who had a car accident in Pakistan, first being treated in a hospital in Pakistan and he became infected with the Bug carrying the NDM-1. He was further transferred to Belgium where he was hospitalized with major leg injury, and despite being administered colistin, the patient died!

We now face a new challenge. Could this superbug mean the end of the beta-lactam antibiotics era?!


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The pursuit of renewable sources of energy just hit a crucial breakthrough. Since the stores of fossil fuel are diminishing as we speak, researchers are trying to exploit the machinery of microorganisms for the production of diverse chemical compounds, which can be consumed by themselves or later channeled into some form of combustible fuel. One major group of those compounds are alkanes, those saturated organic compounds abundantly found in gasolline.

The study started off when ten out of the eleven strains of Cyanobacteria, that were photoautotrophically cultured, produced forms of alkanes, mostly those with 15 & 17 carbons atoms “termed penatdecane and heptadecane respectively”. Logically, that indicates that the ‘alkane-producing gene’ is shared in all ten of them, yet absent in that unlucky 11th strain. So the search was launched.

Trying to pinpoint the gene responsible for the production of alkanes through using a method referred to as subtractive genome analysis, the study authors compared ten genomes of the alkane-producing strains to figure out which genes they have in common. Next, any of those shared genes was immediately eliminated if it had additionally showed up in the genome of the NON-alkane producing strain. Eventually, the researchers were left with 17 genes found in common and the function of 10 of them had already been previously assigned. Through careful scrutiny of the families to which proteins of those remaining 7 genes probably belong to, two of them particularly stood out, being likely participants in the pathway of the alkane synthesis.

And as always, there is no better way to test the hypothesis than to consult a microbiologist’s favorite lab microbe. To our pleasant surprise, extracts from the colonies of Escherichia coli engineered to express both genes did in fact contain alkanes. So, although we are still not fully aboard the track heading the way towards large scale production of alkanes using such microbes, this is definitely a gigantic leap in the right direction!

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