|Year : 2010 | Volume
| Issue : 1 | Page : 86-87
Research snippets from the medical world
Department of Microbiology, Bhopal Memorial Hospital and Research Centre, Raisen Bypass Road, Karond, Bhopal - 462 036, India
|Date of Submission||27-Oct-2009|
|Date of Acceptance||14-Nov-2009|
|Date of Web Publication||6-Jan-2010|
Department of Microbiology, Bhopal Memorial Hospital and Research Centre, Raisen Bypass Road, Karond, Bhopal - 462 036
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Desikan P. Research snippets from the medical world. Indian J Med Microbiol 2010;28:86-7
Bacteria seem to have come to the rescue of the much maligned appendix. For humans, the value of having an appendix seems to be negligible and, given the prevalence of appendicitis, having an appendix can be downright dangerous. However, on the basis of comparative anatomical and phylogenetic approaches (J. Evol. Biol. 22, 1984:2009), it is now contended that the appendix is a specialized organ for harbouring symbiotic bacteria essential for health. It is postulated that due to the constricted opening of the appendix, there is restricted access to bacterial pathogens during gastrointestinal infections, and that bacterial symbiont reconstitution after diarrhoea is achieved rapidly from the populations harboured in the appendix. Thus, far from being useless, positive selection during evolution may well have acted to maintain the appendix.
The accuracy of the results of microbiological investigations depends heavily on the quality of clinical samples received. However, in an attempt at pruning healthcare costs, it has been suggested that using self-administered vaginal swabs (SAVS) for collecting samples for screening for sexually transmitted infections (STIs) may save time and resources and may be more comfortable for patients. A prospective study examining the feasibility of this procedure (Acad Emerg Med. 2009 Apr;16(4):360-3) found that SAVS had a sensitivity of 91%, specificity of 99%, positive likelihood ratio of 91, and negative likelihood ratio of 0.09 in diagnosing STIs.
Over the past few months, Central India has been having an outbreak of suspected dengue fever. Dengue diagnosis depends on serology, which is not useful in the early phase of the disease; and virus isolation, which is laborious and time-consuming. There is need for a rapid, sensitive and high throughput method for detection of the dengue virus in the early stages of the disease. With this in mind, an indigenous technique with a new generation TaqMan Minor Groove Binding (MGB) probe approach was used to develop an improved real time RT-PCR (qRT-PCR) for detection of the virus (Virol J. 2009 Jan 23;6:10). The specificity and sensitivity of the assay was 100% when tested with a panel of 39 known positive and negative samples.
As with any outbreak, there is always potential for panic, and fears of importing cases from other parts of the globe. Dengue seems to be no exception. A study was conducted to determine the utility of the dengue virus NS1 antigen (Ag) rapid test for onsite detection of imported dengue cases at airports (Clin Vaccine Immunol. 2009 Apr;16(4):589-91). Among 22 positive cases of dengue identified from 850 patients with a fever suspected to be dengue, 17 were NS1 Ag test positive. These findings have been used to demonstrate the usefulness of the NS1 Ag rapid test in screening imported dengue cases at airports.
Aedes aegypti, the 'yellow fever mosquito', is the primary vector to humans of dengue fever flaviviruses (DENV). Since vaccines are not yet available for DENV, management of Ae. aegypti remains the primary option to prevent and control outbreaks of the diseases caused by this virus. Permethrin is one of the most widely used active ingredients in insecticides for suppression of adult Ae. Aegypti. An extensive study (PLoS Negl Trop Dis. 2009 Oct 13;3(10):e531) recorded a dramatic increase in the frequency of the Ile1,016 mutation in the voltage-gated sodium channel gene of Ae. aegypti in Mιxico from 1996 to 2009. This mutation has been documented to confer resistance to permethrin. Clearly, we have a lot to learn about survival from mosquitoes as well.
Diagnosis and control of tuberculosis continues to present a global challenge. To help face this challenge, the Stop TB Partnership's New Diagnostics Working Group (NDWG) has presented a new website resource called Evidence-based Tuberculosis Diagnosis, available at: http://www.tbevidence.org . The WHO, Foundation for Innovative New Diagnostics (FIND), the Special Programme for Research and Training in Tropical Diseases (TDR), the Global Laboratory Initiative (GLI), the Francis J Curry National TB Centre, and the Public Health Agency of Canada (PHAC) have contributed to the development of this site. The aim of this website is to provide a comprehensive single source of evidence syntheses, policies, guidelines and research agendas on TB diagnosis. It addresses a longstanding need for a single portal that compiles critical evidence on TB diagnosis, with relevant guidelines for clinicians, health professionals and policy-makers.
Healthcare workers are at high risk of getting infected by Mycobacterium tuberculosis. Surveillance for latent tuberculosis in these high-risk groups is limited by the nonspecificity of the tuberculin skin test (TST) in BCG-vaccinated individuals. The alternative would be to use Mycobacterium tuberculosis antigen-specific interferon-g release assays (IGRAs) like the T-SPOT.TB assay for more accurate latent tuberculosis detection in such groups. A study comparing the utility of an IGRA, the T-SPOT.TB assay, with that of the TST in healthcare workers with a high rate of BCG vaccination (Infect Control Hosp Epidemiol 2009; 30:870-875) found that the high rate of positive baseline TST results in our BCG-vaccinated healthcare workers rendered the TST unsuitable as a surveillance tool in this tuberculosis risk group. This was in contrast to the performance of the IGRA, which enabled better detection of latent tuberculosis in this group. The study also highlighted the need for greater tuberculosis awareness and improved infection control practices in healthcare institutions.
With rapid advances in healthcare, invasive/prosthetic devices are increasingly used for various therapeutic procedures. Unfortunately, these devices are prone to develop biofilms, notorious for their resistance to antibiotics and host defences, which then make most device infections difficult or impossible to eradicate. A timely review (Int J Artif Organs. 2009 Oct 22) examines the potential use of biofilm matrix-degrading enzymes as anti-biofilm agents for the treatment and prevention of device infections and records the utility of many of them in various clinical situations.
With bacterial biofilms getting tough, we need all the help we can get to tackle them - be it from even the "lowly" maggots. A report (Int J Artif Organs. 2009 Oct 24.Epub ahead of print.) indicates that Lucilia sericata larvae (maggots) contain many bioactive compounds which may interfere with S. epidermidis biofilm formation, specifically degrading factors employed in biofilm accumulation, which, in turn, would increase bacterial susceptibility to antibiotics and the host's immune system.
Grandma's homemade remedies for infections may actually prove more effective than antibiotics these days. A study (Phytother Res. 2009 Oct 13. Epub ahead of print) evaluated the effect of essential oils on bacterial growth and Quorum Sensing (QS) using the sensor strain Chromobacterium violaceum CV026, N-acyl homoserine lactone (AHL) producing Escherichia More Details coli ATTC 31298 and the grapevine colonizing Ezf 10-17 strains. Of the tested oils, rose, geranium, lavender and rosemary oils were the most potent QS inhibitors. Eucalyptus and citrus oils moderately reduced pigment production by CV026, whereas the chamomile, orange and juniper oils were ineffective.