Miércoles 20 de Febrero de 2008;09:23 hrs.

Bacterial and fungal infections among diagnostic laboratory workers: evaluating the risks

 

• Ellen Jo Barona and J. Michael Miller. Diagnostic Microbiology and Infectious Disease. Volume 60, Issue 3, March 2008, Pages 241-246
  
• Accidental infections acquired in the laboratory environment are not reportable in a formal forum outside the institution, and therefore, there is little opportunity to evaluate such occurrences and learn from them. We evaluated voluntary responses from 88 facilities, 53 large hospitals (>200 beds) or academic institutions, 32 smaller facilities (<200 beds), and 3 national reference diagnostic laboratories. Thirty-eight of the laboratories (43%), 15 large and 23 small facilities, reported no known exposures during 2002 to 2004. Twenty-one laboratories, 17 large and 4 small institutions, reported at least 1 exposure. Even in this small study, laboratory-acquired infections were reported by 29 laboratories (33%), 24 in large facilities and 5 in small sites. Of the organisms causing laboratory-acquired infections in this survey, Shigella was the most common, followed by Brucella, Salmonella, and Staphylococcus aureus. Although Neisseria meningitidis is perceived to be commonly acquired, only 4 cases were reported by the 88 respondents. Recommendations for reducing exposure risks are provided.....Más...

 

Miércoles 20 de Febrero de 2008;09:20 hrs.

Whipple's disease: new aspects of pathogenesis and treatment

 

• Prof Thomas Schneider MDa, Dr Verena Moos PhDa, Prof Christoph Loddenkemper MDb, Prof Thomas Marth MDc, Florence Fenollar MDd and Prof Didier Raoult MDd. The Lancet Infectious Disease. Volume 8, Issue 3, March 2008, Pages 179-190
  
• 100 years after its first description by George H Whipple, the diagnosis and treatment of Whipple's disease is still a subject of controversy. Whipple's disease is a chronic multisystemic disease. The infection is very rare, although the causative bacterium, Tropheryma whipplei, is ubiquitously present in the environment. We review the epidemiology of Whipple's disease and the recent progress made in the understanding of its pathogenesis and the biology of its agent. The clinical features of Whipple's disease are non-specific and sensitive diagnostic methods such as PCR with sequencing of the amplification products and immunohistochemistry to detect T whipplei are still not widely distributed. The best course of treatment is not completely defined, especially in relapsing disease, neurological manifestations, and in cases of immunoreconstitution after initiation of antibiotic treatment. Patients without the classic symptoms of gastrointestinal disease might be misdiagnosed or insufficiently treated, resulting in a potentially fatal outcome or irreversible neurological damage. Thus, we suggest procedures for the improvement of diagnosis and an optimum therapeutic strategy....Más...

 

Martes 12 de Febrero de 2008; 16:10 hrs.

The Evolution of Norovirus, the “Gastric Flu”

 

• Lopman B, Zambon M, Brown DW PLoS Medicine Vol. 5, No. 2, e42 doi:10.1371/journal.pmed.0050042
• Linguistically speaking, the predominant viral cause of gastroenteritis has been evolving. Once evocatively called winter vomiting disease, the pathogen's name has changed alongside improved scientific understanding. First called Norwalk virus (or Norwalk-like virus) in reference to the Ohio town where specimens from a school outbreak enabled the seminal work that first characterised the virus, it was later dubbed the Small Round Structured Virus following visualisation by electron microscopy. The International Committee on Taxonomy of Viruses later settled on the present name of “norovirus”, classifying it as a member of the Caliciviridae family based on both morphology and phylogeny. A new study published in this issue of PLoS Medicine suggests that the colloquial “gastric flu” may have been the most .....Más.

 

Lunes 28 de Enero 2008; 12:00 hrs.

Campylobacter jejuni Survives within Epithelial Cells by Avoiding Delivery to Lysosomes

 

• Watson RO, Galán JE PLoS Pathogens Vol. 4, No. 1, e14 doi:10.1371/journal.ppat.0040014

• Campylobacter jejuni is one of the major causes of infectious diarrhea world-wide, although relatively little is know about its mechanisms of pathogenicity. This bacterium can gain entry into intestinal epithelial cells, which is thought to be important for its ability to persistently infect and cause disease. We found that C. jejuni is able to survive within intestinal epithelial cells. However, recovery of intracellular bacteria required pre-culturing under oxygen-limiting conditions, suggesting that C. jejuni undergoes significant physiological changes within the intracellular environment. We also found that in epithelial cells the C. jejuni–containing vacuole deviates from the canonical endocytic pathway immediately after a unique caveolae-dependent entry pathway, thus avoiding delivery into lysosomes. In contrast, in macrophages, C. jejuni is....Más.

Lunes 28 de Enero 2008; 11:45 hrs.

Role of ABO Secretor Status in Mucosal Innate Immunity and H. pylori Infection

 

• Lindén S, Mahdavi J, Semino-Mora C, Olsen C, Carlstedt I, et al. PLoS Pathogens Vol. 4, No. 1, e2 doi:10.1371/journal.ppat.0040002

• The fucosylated ABH antigens, which constitute the molecular basis for the ABO blood group system, are also expressed in salivary secretions and gastrointestinal epithelia in individuals of positive secretor status; however, the biological function of the ABO blood group system is unknown. Gastric mucosa biopsies of 41 Rhesus monkeys originating from Southern Asia were analyzed by immunohistochemistry. A majority of these animals were found to be of blood group B and weak-secretor phenotype (i.e., expressing both Lewis a and Lewis b antigens), which are also common in South Asian human populations. A selected group of ten monkeys was inoculated with Helicobacter pylori and studied for changes in gastric mucosal glycosylation during a 10-month period. We observed a loss in mucosal fucosylation and concurrent induction and time-dependent dynamics in gastric mucosal sialylation (carbohydrate marker of inflammation), which affect....Más.

Viernes 25 de Enero 2008; 11:10 hrs.

Isocitrate Dehydrogenase of Helicobacter pylori Potentially Induces Humoral Immune Response in Subjects with Peptic Ulcer Disease and Gastritis

 

• Hussain MA, Naveed SA, Sechi LA, Ranjan S, Alvi A, et al. (2008). PLoS ONE 3(1): e1481 doi:10.1371/journal.pone.0001481. H. pylori causes gastritis and peptic ulcers and is a risk factor for the development of gastric carcinoma. Many of the proteins such as urease, porins, flagellins and toxins such as lipo-polysaccharides have been identified as potential virulence factors which induce proinflammatory reaction. We report immunogenic potentials of isocitrate dehydrogenase (ICD), an important.....Más.

Viernes 25 de Enero 2008; 11:00 hrs.

Molecular Studies in Treponema pallidum Evolution: Toward Clarity?

 

PLoS Neglected Tropical Diseases 2(1): e184 doi:10.1371/journal.pntd.0000184. Syphilis is the best known treponemal infection and the disease has captured the attention of well-known physicians and the imaginations of writers and artists. In contrast, the nonvenereal treponemal infections (yaws, bejel, and pinta) have been endemic in remote regions of Africa, Southeast Asia, and South America, and are thus less well-known in western culture. However, these endemic treponematoses were so prevalent that, between 1952 and 1964, the World Health Organization (WHO) undertook a massive eradication campaign in which over 300 million people in Africa, South America, Southeast Asia, the South Pacific islands, and the Middle East were examined and ~50 million were treated with penicillin. It is estimated that the burden of disease was reduced by...Más.

Miércoles 16 Enero 2008; 21:50 hrs.

Update on Avian Influenza A (H5N1) Virus Infection in Humans

The New England Journal of Medicine 2008; 358:261-273. The unprecedented epizootic of avian influenza A (H5N1) viruses among birds continues to cause human disease with high mortality and to pose the threat of a pandemic. This review updates a 2005 report1 and incorporates information recently published or presented at the Second World Health Organization (WHO) Consultation on Clinical Aspects of Human Infection with Avian Influenza A (H5N1) Virus. Más.

Miércoles 16 Enero 2008; 09:50 hrs.

Probiotic modulation of symbiotic gut microbial–host metabolic interactions in a humanized microbiome mouse model

Molecular Systems Biology 2008; 4:157. Nils Chr. Stenseth, Bakyt B. Atshabar, Mike Begon et al. The transgenomic metabolic effects of exposure to either Lactobacillus paracasei or Lactobacillus rhamnosus probiotics have been measured and mapped in humanized extended genome mice (germ-free mice colonized with human baby flora). Statistical analysis of the compartmental fluctuations in diverse metabolic compartments, including biofluids, tissue and cecal short-chain fatty acids (SCFAs) in relation to microbial population modulation generated a novel top-down systems biology view of the host response to Más.

Martes 1 Enero 2008; 22:22 hrs.

Plague: Past, Present, and Future

PLoS Medicine Vol. 5, No. 1, e3 doi:10.1371/journal.pmed.0050003 Nils Chr. Stenseth, Bakyt B. Atshabar, Mike Begon et al. Recent experience with SARS (severe acute respiratory syndrome) and avian flu shows that the public and political response to threats from new anthropozoonoses can be near-hysteria. This can readily make us forget more classical animal-borne diseases, such as plague. Más.

Martes 1 Enero 2008; 22:20 hrs.

Key Role for Clumping Factor B in Staphylococcus aureus Nasal Colonization of Humans

PLoS Medicine Vol. 5, No. 1, e17 doi:10.1371/journal.pmed.0050017 Heiman F. L. Wertheim, Evelyn Wals,, Roos Choudhurry et al. Staphylococcus aureus permanently colonizes the vestibulum nasi of one-fifth of the human population, which is a risk factor for autoinfection. The precise mechanisms whereby S. aureus colonizes the nose are still unknown. The staphylococcal cell-wall protein clumping factor B (ClfB) promotes adhesion to squamous epithelial cells in vitro and might be a physiologically relevant colonization factor.Más.

Jueves 11 Enero 2008; 23:00 hrs.

Fiebre tifoidea: Emergencia, cúspide y declinación de una enfermedad infecciosa en Chile

Rev. chil. infectol. 2007:24;435-440. Enrique Laval R. y Catterina Ferreccio R.En este artículo se presenta la historia de la fiebre tifoidea (FT) en Chile desde su reconocimiento como entidad nosológica hasta su situación actual. De la historia destaca la confusión que hubo en Chile durante muchos años entre esta enfermedad y el tifus exantemático a pesar de que la fiebre tifoidea ya había sido individualizada y caracterizada en la primera mitad del siglo XIX en Europa. Esto se podría explicar porque.....Más.

Jueves 11 Enero 2008; 22:45 hrs.

Immunogenicity of a Tetravalent Meningococcal Glycoconjugate Vaccine in Infants

JAMA. 2008;299(2):173-184. Immunization with a meningococcal tetravalent (serogroup ACWY) glycoconjugate vaccine is recommended for all US adolescents. However, the currently licensed vaccine is poorly immunogenic in infancy, when the highest rates of disease are observed.....Más.

Miércoles 09 Enero 2008; 22:55 hrs.

A Potential New Pathway for Staphylococcus aureus Dissemination: The Silent Survival of S. aureus Phagocytosed by Human Monocyte-Derived Macrophages

PLoS ONE 3(1): e1409 doi:10.1371/journal.pone.0001409. Malgorzata Kubica, Krzysztof Guzik, Joanna Koziel, Miroslaw Zarebski,et al. Although considered to be an extracellular pathogen, Staphylococcus aureus is able to invade a variety of mammalian, non-professional phagocytes and can also survive engulfment by professional phagocytes such as neutrophils and monocytes. In both of these cell types S. aureus promptly escapes from the endosomes/phagosomes and proliferates within the cytoplasm, which quickly leads to host cell death. In this report we show that S. aureus interacted with human monocyte-derived macrophages in a very different way to those of other mammalian cells. Upon phagocytosis by macrophages, S. aureus persisted intracellularly in vacuoles for 3–4 days before escaping into the cytoplasm and causing host cell lysis. Until the point of host cell lysis the infected macrophages showed no signs of apoptosis or necrosis and were functional. They were able to eliminate intracellular staphylococci if prestimulated with....Más.

 

Miércoles 09 Enero 2008; 09:41 hrs.

Smallpox Vaccine Alternative Identifieds

ScienceDaily (Jan. 9, 2008) — University of California, Irvine infectious disease researchers have shown the effectiveness of a potential alternative to the existing smallpox vaccine that can replace the current biodefense stockpile for this lethal virus. Philip Felgner and Huw Davies with the Department of Medicine found that the modified vaccinia virus Ankara (MVA) produced the same antiviral response in human and animal studies as the current smallpox vaccine, Dryvax. The study is part of a national effort to develop a replacement for the Dryvax vaccine, which causes serious complications in some people.

“Studies have shown MVA to be a much safer vaccine product that takes advantage of modern technology,” Felgner said. “We are pleased that our advanced analytical methods may help to bring an effective and safer vaccine to the public.”

Smallpox was declared eradicated worldwide in 1980; the last naturally occurring case in the world was in Somalia in 1977. Routine vaccination against smallpox in the U.S. stopped in 1972, and Dryvax production was halted in 1982.

Both Dryvax and MVA are strains of vaccinia virus, which is related to the smallpox virus. The antibodies created by vaccinia virus infection protect a person against a lethal smallpox infection, making it suitable for use as a vaccine. Unlike smallpox virus, vaccinia creates a very mild infection and is completely safe for healthy individuals.

Although Dryvax was effective during the eradication campaign in the 1960s and ’70s, its manufacturing methods are outdated by today’s standards, and it is also associated with significant risk of adverse reactions for immune-compromised individuals.

The National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health, identified MVA as a possible candidate to replace Dryvax. MVA was first developed in the 1970s and has been administered to animal species and humans with little or no adverse side effects.

In the study, Felgner and Davies applied blood serum samples taken from both humans and animals given the MVA or Dryvax vaccines to “microarray” chips containing more than 200 vaccinia virus proteins, on which they simultaneously studied how the serum antibodies responded to all the vaccinia proteins. 

The researchers found that these antibody responses were similar in both the animal and human subjects regardless whether they were given MVA or Dryvax, suggesting that MVA contains antiviral properties similar to those in Dryvax.

This similarity is vital, Davies says, because if a vaccine initiates an immune response in humans that matches the one in animals that are protected against lethal pox viruses, then public health officials will have more confidence that the vaccine will be effective in humans.

“This is particularly important for vaccines against lethal infections like smallpox, where human clinical trials cannot be done,” he added.

The study marked a collaboration between UC Irvine and ImmPORT Therapeutics Inc. in Irvine, who manufacture the arrays. The animal tests were done by the NIAID, and human studies were held at Saint Louis University. The NIH supported the study.

UC Irvine is home to the Pacific-Southwest Center for Biodefense and Emerging Infectious Diseases Research – one of only 10 federally funded regional centers dedicated to research for countering bioterrorism and infectious disease threats.

About the protein microarray laboratory

The protein microarray laboratory at UC Irvine and ImmPORT has developed an efficient method for producing all of the proteins from infectious agents like smallpox and printing them onto microarray chips. The chips can be probed with serum from vaccinated individuals to study the antibodies that are produced after vaccination or infection. The team has produced and printed microarray chips containing 16,000 different proteins from 20 infectious agents, including the organisms responsible for tuberculosis and malaria.

Full results are published in the Journal of Virology.

Adapted from materials provided by University of California -- Irvine (2008, January 9). Smallpox Vaccine Alternative Identified. ScienceDaily. Retrieved January 9, 2008, from http://www.sciencedaily.com/releases/2008/01/080107090951.htm