Revista latinoamericana de microbiologia最新文献

Since the last decade of the XX century has been increasing the frequency of outbreaks with highly pathogenic avian influenza viruses among poultry and direct transmission of these viruses to humans. These events have ignited great concern about the pandemic potential of these viruses, for that reason the study and characterization of the previously influenza viruses involved in pandemics or outbreaks has been considered of great importance. This review presents and compares the different influenza viruses involved in the XX century pandemics and outbreaks, with emphasis in the cellular receptors used by avian and human influenza viruses. And the recently finding that human respiratory tract contains both type of receptors, and finally which factors could allow a successful direct human infection with avian viruses, and how theses viruses could be transmitted among the human population.

In this review we cover the biological control of insects, bacteria and fungus that affect different crops. Using different microorganism as bacteria viruses and fungus can do the biological control of these important problems. In this work we describe with detail the mode of action of the different microorganisms used to control insects and plant diseases. We also present novel strategies to improve the efficiency of these microorganisms against their targets and we present the development and production of several formulations to be used in the fields for the biological control of some plant problems.

Bacterial resistance to antibiotics is a major public health problem around the world causing high rates of morbi-mortality and economic problems in hospital settings. Major bacterial causing nosocomial infections are: extended-spectrum beta-lactameses (ESBL) producing enterobacteria, methicillin resistance Staphylococcus aureus, coagulase negative Staphylococcus, metallo fl-lactamases (MBL) producing Pseudomonas aeruginosa, Streptococcus pneumoniae, Enterococcus spp, Acinetobacter baumani. This last bacteria is not very often isolated in hospital settings yet, but it is multi-resistance pathogen causing high mortality. Helicobacter pylori, which is not a nosocomial pathogen but is associated to gastric diseases (from gastritis to gastric cancer). Infections prevention, to obtain an accuracy diagnostic and effective treatment, use antibiotic wisely and pathogen dissemination prevention (hand washing), are important steps to control the bacterial resistance.

Candida glabrata is an opportunistic fungal pathogen that has become increasingly frequent in bloodstream and mucosal infections in immunocompromised patients. C. glabrata is phylogenetically more closely related to S. cerevisiae than to C. albicans, and some well identified virulence factors in C. alhicans do not seem to be conserved in C. glabrata. However. other important traits are shared by both organisms, and these may play a role in the adaptation and survival in the host as opportunistic pathogens. Both species adhere tightly to host cells, and C. globrata has a large family of subtelomeric genes encoding cell surface proteins that mediate this adherence. Expression of these genes is regulated by a chromatin-based negative regulation termed subtelomeric silencing. C. albicans also possesses several adhesins although they are not regulated by this mechanism. C. albicans and C. glabrata have been considered asexual, but recent work has demonstrated the existence of a cryptic sexual cycle in C. albicans. The fact that C. glabrata contains all of the genes essential for mating suggests the possibility that C. glabrata might also have a tightly regulated sexual cycle. Both organisms can form biofilms and can undergo phenotypic switching which could be important for rapid adaptation to the changing environmental conditions encountered in the host as opportunistic pathogens.

In the last ten years a great number of RNAs have been discovered that function by regulating gene expression and do not code for a protein. This RNAs are named ncRNAs or sRNAs (non coding RNAs or small RNAs). More than 70 sRNAs have been documented in Escherichia coli and function by inhibiting/ promoting translation or degradation, some have intrinsic catalytic properties and others modify the activity of a protein. The mechanisms of action of some of them will be reviewed as well as the efforts to find new sRNAs by systematic oriented searches.

Cyanobacterial biofilms are complex communities of microorganisms that cause damaging activity on historic monuments. A combined molecular approach shows that cyanobacteria belonging to the order Pleurocapsales are the main colonizers at the Mayan site of Uxmal, Mexico, confirming previous microscopic and culture-based reports. An important, previously unrecognized non-cyanobacterial community comprising Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes has also been found in Uxmal. Cyanobacterial communities in Palenque were composed of over 10 species, mainly coccoid forms. A novel PCR method designed to directly amplify DNA from uncultured cyanobacterial cells on historic buildings in Brazil indicated that the identified cyanobacteria sequenced corresponded to their appropriate morphological groups (as defined by both the bacterial and botanical codes). However, their homologies with deposited sequences were, in general, low. Terrestrial cyanobacteria from stone surfaces in Brazil, again mainly coccoid, formed a distinct population that differed from the better-studied aquatic members. Overall, results here show demonstrate that coccoid cyanobacteria are the main colonizers on Latin American monuments under tropical and subtropical conditions and the assessment of their potential deteriogenic activity requires the further development of rapid molecular techniques. Polyphasic studies are essential to increase our knowledge of the diversity of terrestrial biofilms and of global microbial diversity.

The papers included in this section were previously exposed in the Microbial Communities Symposium organized in XXXV Congreso Nacional de Microbiología. The contributions try to understand the diversity associated to different microbial communities from a molecular perspective, regardless of culture or including a cultured based perspective. Thus, natural models, including bacteria associated to insect tissues, biofilms and microbial communities in man-made habitats as oil pipelines, anaerobic digestors and fermented foods are described. The papers explain several questions and exhibit different perspectives, but maintain a methodological unit, illustrating the knowledge and applicative potential of microbial ecology from a molecular point of view.

Human and bovine tuberculosis (TB) are currently a serious health problem in Latin America. Although the causal agents were discovered more than one century ago, the control of these illnesses is still beyond our reach: human TB accounts for more than one hundred deaths each day in this region, whereas bovine TB represents a public health risk as well as a major economic problem. We herein analyze the situation of human and bovine TB in Latin America, and present studies from our laboratories on bacterial virulence factors, intrinsic resistance features in the host, and the protective response induced in cattle through vaccination or immunization. Finally, the convenience for implementing and/or revising the use of currently available tools for TB control in the region is discussed.

Recent evidences establish that the evolution of the Human Immunodeficiency Virus in the present epidemic has an adaptive component. The main selective pressure on HIV consists of cytotoxic T lymphocytes (CTLs) recognition of viral peptides on infected cells associated to class I HLA molecules. Since each HLA allele recognizes a defined repertoire of peptides, escape mutations will reflect the HLA alleles present in individuals or populations. Initial findings demonstrated the possibility of adaptive evolution in HIV, by showing the role of CTLs in infection control, the emergence of escape mutants, and their ability to be transmitted and accumulate. The subsequent finding of a population-level association between viral sequence polymorphisms and particular alleles in the hosts was considered a mark of CTL selection on HIV. Subsequent studies experimentally verified the immunological mechanisms of this selection and it is present occurrence. The strategies of these studies, based on the evaluation of immunological hypothesis suggested by statistical findings on virus and host polymorphisms, offer novel opportunities of research in topics as the interaction between immune and antiretroviral drug pressures, and the biological relevance of fitness of viral variants.