The First Rapid Blood Test for MRSA is in the Market
In recent years, the incidence of methicillin-resistant Staphylococcus aureus (MRSA) infection have been on the rise. This has especially become a problem in hospitals where MRSA infections have become synonymous to healthcare-associated infections.
S. aureus is a very common bacterial species that causes pimples and mild skin and wound infections. However, years of antibiotic use gave rise to strains which are resistant to the antibiotic methicillin as well as to other drugs. The MRSA strains can cause life-threatening conditions such as sepsis, infections of surgical sites, and pneumonia.
The US FDA has recently approved the first quick test to identify MRSA in the blood. Using molecular methods, the BD GeneOhm StaphSR Assay can detect genetic material from the common, less dangerous methicillin-sensitive S. aureus (MSSA) as well as the drug-resistant deadly MRSA strains [1, 2]
Early detection of MRSA infections is crucial in their treatment and management. Using standard diagnostic laboratory tests, it takes 2 days to identify MRSA in blood samples. With the new rapid test, results are available within 2 hours. This is especially good news to the public health community which had to deal with the rapid rise in the incidence of MRSA infections in hospitals and clinics. Immunocompromised patients are especially susceptible.
The BD GeneOhm StaphSR test is manufactured by BD Diagnostics, a subsidiary of BD of Franklin Lakes, N.J.
[1] FDA News, 2 Jan 2008. FDA Clears First Quick Test For Drug-Resistant Staph Infections.
Cluster of human avian flu cases in Pakistan
The recent H5N1 outbreak in Pakistan causes much concern because it is the largest cluster of human cases of the avian flu since 2006 in Indonesia. 8 suspected cases have so far been reported in the outbreak, 2 of which were fatal.
The World Health Organization, in cooperation with Pakistani health officials, is closely monitoring the area, as well as checking hospital and clinic registers for possible unreported retrospective cases. Cases clustered closely in a small geographical area are highly crucial in the epidemiological monitoring of avian flu because they may represent cases of the human-to-human transmission of the disease. To date, transmission has only been reported from animal-to-animal and from animal-to-human.
Nature News, 17 Dec 07
WHO news, 15 Dec 07
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The STEP Trial: Discontinuation and Unblinding
The STEP Trial: The STEP study was a phase II multinational, randomized, double-blind, placebo-controlled clinical trial which was started in 2004.
The Investigational Drug: The V520 HIV vaccine candidate is a combination of 3 components made from a weakened adenovirus type 5. The vaccine serves as a vector of 3 synthetically produced HIV genes known as gag, pol and nef. These HIV genes would supposedly induce “an HIV-specific immune response through the body’s own CD8 T-cells, which become programmed to recognize and kill HIV infected cells.”
The Sponsors: The STEP trial was sponsored by Merck, the National Institute of Allergy and Infectious Diseases (NIAID), and the HIV Vaccine Trials Network (HVTN).
The The Study Population: 3,000 HIV-negative participants from different ethnic groups. They are aged between 18 and 45 years of age and at high risk of HIV infection. The trial was conducted in the United States, Peru, Brazil, Dominican Republic, Haiti, Jamaica, Australia, and South Africa.
The Efficacy Endpoints: The primary efficacy endpoints were to evaluate the ability of the vaccine to prevent HIV infection and to reduce virus proliferation in infected individuals.
The Discontinuation: On 21 September 2007, Merck announced the discontinuation of the STEP study due to poor efficacy profile. The vaccine did not prevent infection nor reduce viral loads in the bloodstream of HIV-positive individuals.
The Unblinding: In November 2007, Merck and HVTN announced their decision to unblind the trial based on concerns that the vaccine may actually have induced susceptibility to HIV infection in study participants. Sources:
HVTN Press Release 13 Nov 2007
GRACE: Combating Antimicrobial Resistance
The use of antibiotics “are not justified to reduce the risk of serious complications for upper RTI, sore throat, or otitis media.” This was one of the main conclusions of a retrospective cohort study in the UK as reported recently in BMJ. The study looked into more than 3 million cases of RTI found in the UK General Practice Research Database [1].
There have always been concerns about the indiscriminate use of antibiotics, especially as preemptive measure to reduce complications of upper RTI. The emergence of multidrug-resistant bacterial strains indicates that these concerns are justified.
In Europe, a one of a kind consortium is tackling the problem of antimicrobial resistance in community-acquired lower RTI. The Network of Excellence GRACE consists of “17 academic groups with a wide spectrum of expertise, spread widely across the EU Member States.” Among these are two leading European scientific societies, the European Society of Clinical Microbiology and Infectious Diseases and European Respiratory Society. GRACE integrates clinical research with genomics as well as education and training of medical professionals [2].
Abbreviations:
GRACE = Genomics to Combat Resistance against Antibiotics in Community-acquired lower respiratory tract infection in
Europe
RTI = respiratory tract infection
Sources:
Cholera pathogen Vibrio cholerae can grow in freshwater: epidemiological and immunological consequences
The majority of bacterial species under the Vibrio genus are common flora in brackish waters and estuaries. The causative agent of dysenteric disease cholera, Vibrio cholerae, wasn’t thought to be any different. The disease has always been associated with ingestion of contaminated water and sea food. However, researchers at the Swiss Federal Institute for Aquatic Science and Technology (EAWAG) showed that V. cholerae not only grows but actually thrives in freshwater.
The study focused on the V. cholerae O1 Ogawa El Tor strain, one of the serotypes responsible for the recently reported outbreaks in India. Study results show that the bacterium is actually euryhaline and can grow in a wide range of salinities ranging from brackish to lake waters. A determinant factor for its growth in freshwater is the amount of apparent assimilable organic carbon (AOCapp). V. cholerae produces a toxin that causes the characteristic diarrheal symptoms of the disease.
In another European study, Belgian researchers looked more in detail into the transport mechanisms of the B-protomer subunit of the cholera toxin. According to Vanden Broeck and colleagues (2007), the B-subunit “displays the capacity to fortify immune responses to certain antigens, to act as a carrier and to be competent in inducing immunological tolerance.”These findings have some consequences on the epidemiology and preventive strategies of cholera.
The first study highlights the risks of contamination not only in coastal waters but in inland areas and lakes while the second study indicates a potential use for the cholera toxin in vaccine development.