Traditional lab tests for disease diagnosis can be too expensive and cumbersome for the regions most in need. George Whitesides’ ingenious answer is a foolproof tool that can be manufactured at virtually zero cost, as shown in this video:
Swarming is flagella-driven bacterial group motility over a surface, which is observed in the laboratory on media solidified with agar. The percentage of agar is critical for enabling swarming. Some bacteria like Vibrio parahaemolyticus and Proteus mirabilis can swarm readily on higher percentage agar, whereas others like Salmonella, Escherichia coli, Serratia, Pseudomonas, and Bacillus swarm only on lower percentage agar. Hard-agar swarmers differentiate into specialized swarm cells that are elongated and have increased flagella. Medium-agar swarmers generally do not display a similar differentiated morphology. In many of the latter class of swarmers (e.g. Serratia, Pseudomonas, Bacillus), movement is enabled by powerful extracellular surfactants whose synthesis is under quorum-sensing control. Surfactants lower surface tension and allow rapid colony expansion. Salmonella and E. coli do not appear to make such surfactants.
Swarming bacteria exhibit adaptive resistance to multiple antibiotics. Analysis of this phenomenon has revealed the protective power of high cell densities to withstand exposure to otherwise lethal antibiotic concentrations. This paper shows that that high cell densities promote bacterial survival, even in a nonswarming state, but that the ability to move, as well as the speed of movement, confers an added advantage, making swarming an effective strategy for prevailing against antimicrobials. There is no evidence of induced resistance pathways or quorum-sensing mechanisms controlling this group resistance, which occurs at a cost to cells directly exposed to the antibiotic. This work is relevant to the adaptive antibiotic resistance of bacterial biofilms.
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Coldwater and tropical fish are the third most popular pet in the UK after cats and dogs. Over 3 million homeowners have a pond in their garden and many of these are stocked with fish, some of which, like koi carp, are very expensive. As Keith Way describes in this article in Microbiology Today (pdf) a whole host of viruses are in the environment just waiting to infect them with harmful diseases:
With the discovery of non-filterable disease agents, or viruses, in the late 19th century there came a greater realization of the role that viruses may play in infectious diseases of fish. However, the breakthrough for fish virology came with the general developments in virological techniques that blossomed in the 1950s and 60s. In particular, visualization of viruses by electron microscopy, improvements in protein and nucleic acid analysis and, most significantly, the isolation of viruses on continuous (immortal) fish cell lines. At the same time, aquaculture around the world developed in the 1960s and 70s, and farming of fish and fish-keeping rapidly increased. With these developments and, more recently, the global increase in trade in ornamental fish there has been an increase in new diseases and the emergence of serious virus diseases. Viruses that have caused serious but isolated disease outbreaks in cyprinid species and some ictalurid (catfish) species, and may affect coldwater ornamental fish, include aquareoviruses, coronaviruses, poxviruses and iridoviruses. More serious disease epidemics in ornamental species have been caused by rhabdoviruses and herpesviruses.
Nearly half of adolescents admitted to two public hospitals in Zimbabwe are HIV positive according to a new paper in PLoS Medicine. This study examines the causes of unselected acute hospitalization in adolescents, and serves to highlight the growing crisis of HIV acquired at birth in teenagers and young adults in the developing world. Each 10-18 year old participant completed a questionnaire about themselves and their health and underwent standard investigations, including HIV testing. Nearly half of participants were HIV positive; they were more likely to be stunted, to have pubertal delay, and to be maternal orphans or have an HIV-infected mother than HIV-negative adolescents. 69% of HIV-positive participants were admitted to hospital because of infections such as tuberculosis or pneumonia whereas only 19% of the HIV-negative participants were admitted for infections. 22% of the HIV-positive participants died while in hospital compared to only 7% of the HIV-negative participants.
Few studies have addressed the prevalence of perinatally-acquired HIV in older children and adolescence, perhaps because it was thought that children infected at birth were unlikely to survive beyond 5 years of age. Additionally, while the researchers assessed causes of hospitalization such as infectious disease or chronic underlying disease, they did not assess underlying mental health conditions. In the developed world, the most common reasons for psychiatric hospitalization for HIV-infected children were for depression or behavioral disorders and calls for the impact of death and chronic ill health of caregivers or siblings on HIV-infected adolescents in the developing world require investigation.
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Should we destroy the remaining laboratory stocks of smallpox virus?
Now that the 20th century has passed into the domain of history books, we can retrospectively begin to assess the relative contributions that the many advances in the realm of infectious disease have actually made to public health in general. At the top of this virtuous list will surely be the discovery of antibiotics in the 1930s and the use of vaccination to eradicate smallpox as an extant human disease in the 1960s and 1970s. As clearly pointed out in a recent book by D. A. Henderson, one of the leaders of the global smallpox eradication program, this task of ridding Homo sapiens from the curse of this ancestral disease was neither easy nor without controversy. In fact, the history of the many consequences of smallpox on humankind reads like a long litany of human misery and calamitous events, but is juxtaposed with the more noble accomplishments that began with the discovery of vaccination by Jenner in 1798 and culminated with the World Health Organization (WHO) certifying the world free of smallpox in 1980. With this singular accomplishment, as many as 60–100 million individuals who would have been predicted to die of smallpox have been spared from a truly gruesome death. Nevertheless, the narrative of smallpox did not stop with its eradication as a pandemic human disease. Instead, we find ourselves still wrestling with an issue that intermingles public health policy, philosophy, national security, and bioterrorism, and affects our perceptions of research ethics with extreme pathogens in general. It boils down to a not-so-simple question: What exactly should the Victor do with the Vanquished?
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