Monday, March 12, 2012

Occurrence, distribution and bioaccumulation of antibiotics in the Haihe River in China.

Occurrence, distribution and bioaccumulation of antibiotics in the Haihe River in China.

March 2012


State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.


The occurrence, distribution and bioaccumulation of 22 antibiotics, including eight fluoroquinolones (FQs), nine sulfonamides (SAs) and five macrolides (MLs), in the Haihe River were investigated. Surface water, sediment and fish samples were analyzed by HPLC-MS/MS. Ofloxacin, sulfamethoxazole, sulfadiazine, erythromycin and roxithromycin were found in all surface water samples. SAs were the predominant antibiotics in surface water samples in the mainstream of Haihe River, with the maximum concentration of 201 ng L(-1) for sulfamethoxazole. Compared with Haihe River, higher concentrations ofantibiotics were found in the surface water samples in the Dagu and Chentaizi Drainage Rivers. The antibiotics pollution in the mainstream of Haihe River may derive from its tributaries, whereas the wastewater from fish ponds was not the main source of FQs, SAs and MLs in the river water. In sediment samples, FQs were the most frequently detected antibioticsand their concentrations were much higher than SAs and MLs. The high concentrations and detection frequencies of FQs in sediments indicate that sediments are an important reservoir for FQs as they are strongly adsorbed onto sediments. Ciprofloxacin and erythromycin exhibited potential bioaccumulation in crucian carp, with mean bioaccumulation factors of 3262 L kg(-1) and 4492 L kg(-1), respectively.

RSC Publishing

Monday, March 05, 2012

Scientists shocked to find antibiotics alleviate symptoms of schizophrenia

Scientists shocked to find antibiotics alleviate symptoms of schizophrenia

March 5, 2012

By Jeremy Laurance

A CHEAP antibiotic normally prescribed to teenagers for acne is to be tested as a treatment to alleviate the symptoms of psychosis in patients with schizophrenia, in a trial that could advance scientific understanding of the causes of mental illness.

The National Institute for Health Research is funding a £1.9m trial of minocycline, which will begin recruiting patients in the UK next month. The research follows case reports from Japan in which the drug was prescribed to patients with schizophrenia who had infections and led to dramatic improvements in their psychotic symptoms.

The chance observation caused researchers to test the drug in patients with schizophrenia around the world. Trials in Israel, Pakistan and Brazil have shown significant improvement in patients treated with the drug.

Scientists believe that schizophrenia and other mental illnesses including depression and Alzheimer'sdisease may result from inflammatory processes in the brain. Minocycline has anti-inflammatory and neuroprotective effects which they believe could account for the positive findings.

Details of the trial were presented to the independent Schizophrenia Commission by Bill Deakin, professor of psychiatry at the University of Manchester, who is the lead investigator. The 12-member commission, set up by the mental health charity Rethink, is looking into the treatment and care of people with schizophrenia, and is due to report in the summer.

The first account of minocycline's effects appeared in 2007 when a 23-year-old Japanese man was admitted to hospital suffering from persecutory delusions and paranoid ideas. He had no previous psychiatric history but became agitated and suffered auditory hallucinations, anxiety and insomnia.

Blood tests and brain scans showed no abnormality and he was started on the powerful anti-psychotic drug halperidol. The treatment had no effect and he was still suffering from psychotic symptoms a week later when he developed severe pneumonia.

He was prescribed minocycline to treat the pneumonia and within two weeks the infection was cleared and the psychosis resolved. Minocycline was stopped and his psychiatric symptoms worsened. Treatment with the drug was resumed and within three days he was better again. Halperidol was reduced but he remained on minocycline. Two years after his psychotic episode, he was still well.

The UK trial aims to recruit 175 patients recently diagnosed with schizophrenia, half of whom will be randomly allocated to take minocycline with their standard anti-psychotic treatment while the remainder take a placebo.

Brain scans will be carried out at the start and end of the 12 month trial to compare loss of grey matter – an effect of schizophrenia – in the two groups. Tests will also measure inflammatory markers in the blood.

Professor Sir Robin Murray, chair of the Schizophrenia Commission said: "Infection or inflammation might be involved in a minority of people with acute psychosis and minocycline might counter this. In depression inflammatory markers go up and in Alzheimer's too."

Fecal material prevails when antibiotics fail

Fecal material prevails when antibiotics fail

March 4, 2012
By Rick Ruggles
World-Herald Staff Writer

Sometimes medical treatment must be as gritty as the disease it combats.

Doctors in Omaha and elsewhere increasingly place donated, diluted fecal material into patients’ guts to fight antibiotic-resistant bacteria called clostridium difficile, or C. diff. The infection kills thousands of patients each year.

The therapy, which appears to work when antibiotics fail, is on the verge of widespread use. Antibiotics, in fact, are a major part of the problem.

The drugs sometimes destroy the diverse group of bacteria in the gut, allowing C. diff bacteria to move in and take over.

The gut and its fecal matter are a world of their own, teeming with rich, diverse microscopic life. A pea-size piece of stool contains millions and millions of bacteria, including hundreds of varieties. Which bacteria are “good” and which are “bad,” or whether they work in teams for specific purposes, isn’t clear.

“It’s a very complicated and complex environment that we don’t really understand,” said Dr. Alex Hewlett, a University of Nebraska Medical Center faculty member.

UNMC plans to collaborate with a cluster of researchers at the University of Nebraska-Lincoln to learn more about the gut.

Scientists believe the complex environment in the intestines helps digest food, stimulate the immune system and produce vitamins.

Although physicians typically use specific antibiotics against C. diff, a small percentage of patients relapse repeatedly. Clostridium difficile causes diarrhea, abdominal pain, weakness and fever and in rare instances leads to kidney failure, colon removal or death.

“This is a big problem,” Dr. Ed Schafer of Omaha, a gastroenterologist with Midwest Gastrointestinal Associates, said of C. diff.

“By the time they’re this sick, they’re willing to try anything.”

The nation faces a growing problem with C. difficile, which finds its way onto toilet lids, tables and other surfaces through fecal matter, and can sit there for weeks as a microscopic, hard spore. The victims ingest the bacteria.

Killing the spores on surfaces requires bleach.

The federal Centers for Disease Control and Prevention reported that 7,285 Americans died of the infection in 2009, up from 793 in 1999. The increase may be attributable to greater antibiotic resistance and the emergence of a more harmful strain of the bacteria.

The University of Iowa Hospitals and Clinics plan to use the fecal transplant therapy, although they haven’t yet. Methodist Hospital physicians have decided against it for now and have chosen to use a new antibiotic against C. diff.

Schafer said his group has used the treatment, sometimes called a “fecal transplant,” at least six times in recent years, succeeding each time in beating C. diff.

UNMC scientists have used it four times since late last year, each time successfully. They aren’t keen on the term “fecal transplant.”

“'Enteric biotherapy' is a little more pleasing term,” Hewlett said.

Marian Reyburn didn’t care what the treatment was called or what it involved. She just wanted to get better.

She attributed her C. diff to taking an antibiotic after a root canal in September 2010. She became sick and was diagnosed as having C. diff the next month.

Reyburn, who is in her 80s, battled C. diff for more than a year. She had 10 to 27 bowel movements daily and grew increasingly weak.

She and her husband, Harry, took pride in their active lives. After she became ill, he had to lift her out of bed or out of a chair. She couldn’t walk across the room without help. She had to stop driving, taking her watercolor classes, serving her church and volunteering for the Salvation Army and a local hearing-loss group.

She was placed on antibiotics and hospitalized several times. Nothing worked.

Dr. Mark Rupp, chief of the division of infectious diseases at UNMC, recommended a fecal transplant.

By this time, Marian Reyburn was extremely ill and weak. “I had to do something,” she said.

Harry Reyburn donated the fecal matter.

The procedure was done in January and she improved within several days. “And it is wonderful to feel better,” Marian Reyburn said last week.

Depending on who oversees the therapy, scientists or the patients themselves prepare the material. In either case, it is watered down with a saline solution and mixed into a thick slurry. Then it’s run through a cheesecloth or coffee filter.

What’s left is a thin, brown solution that is filled with bacteria. It can be transplanted either through the colon with a colonoscope or an enema or through a nasogastric tube that is threaded into the digestive tract through the nose. It’s typically done the latter way in Omaha.

Fecal transplants aren’t new. A December 2011 report in a national journal said they first were noted in 1958 when they were used to treat a different disease, pseudomembranous enterocolitis. With little doubt, though, fecal transplants are on the cusp of far more use. Scientific papers say the treatment is 90 percent effective against the most resistant C. diff.

Rupp said fecal transplants also may be used against some other diseases, such as pseudomonas infection and vancomycin-resistant enterococci, or VRE.

UNMC will bring UNL scientists into the project because the Lincoln campus has a Gut Function Initiative that conducts research into the intestines and their microorganisms.


Saturday, March 03, 2012

Catalysis and sulfa drug resistance in dihydropteroate synthase.

Catalysis and sulfa drug resistance in dihydropteroate synthase.

Mar 2012


Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.


The sulfonamide antibiotics inhibit dihydropteroate synthase (DHPS), a key enzyme in the folate pathway of bacteria and primitive eukaryotes. However, resistance mutations have severely compromised the usefulness of these drugs. We report structural, computational, and mutagenesis studies on the catalytic and resistance mechanisms of DHPS. By performing the enzyme-catalyzed reaction in crystalline DHPS, we have structurally characterized key intermediates along the reaction pathway. Results support an S(N)1 reaction mechanism via formation of a novel cationic pterin intermediate. We also show that two conserved loops generate a substructure during catalysis that creates a specific binding pocket for p-aminobenzoic acid, one of the two DHPS substrates. This substructure, together with the pterin-binding pocket, explains the roles of the conserved active-site residues and reveals how sulfonamide resistance arises.


Effects of antibiotics on dental implants: a review.

Effects of antibiotics on dental implants: a review.

Feb 2012


Schulich School of Medicine & Dentistry, University of Western Ontario, Canada.


There are many reasons for dental implant failure, the development of bacteremia is concern for dentists. This is due to the possibility of unfavorable result such as implant loss or the need for re-treatment. In general, antibiotic prophylaxis is recommended for high risk patients such as individuals with an immunodeficiency, infectious endocarditis, or previous prosthetic instrumentation.

However regarding clinically healthy, low and moderate risk individuals the use of antibiotics in implant dentistry is controversial. Another major concern regarding the over prescription of antibiotics is the selection of antibiotic resistant bacteria. A better understanding of the efficacy of prophylactic treatments regarding dental implantation is crucial. Thus a literature review and comparison of survival rates of dental implants with regimens of no, pre or post prophylaxis was performed using systematic literature review using reliable electronic databases.

Retrospective or prospective controlled studies were examined for the influence of preoperative and/or postoperative or no antibiosis on dental implant success rate. Of the 11406 implants used in this literature review, cases with no antibiotics had a 92 % success rate, cases with pre-op antibiotic alone had a 96% success rate, cases with post-op antibiotic alone had a 97% success rate and cases with both pre and post-op antibiotic had a success rate of 96%. Thus, the results from this literature review show a > 90% success rate when antibiotics are used compared to when they are not used. Thus, no benefit is seen from the use of antibiotic prophylaxis in low and moderate risk dental implant patients.

KEYWORDS: Dental implants; Pre-operative prophylactics; Post-operative prophylactics; Success rate.