Engineering of bacterial exopolysaccharides: from synthesis to properties

Dissertação para obtenção do Grau de Doutor em Engenharia Química e Bioquímica

Politics, Commerce, and Colonization in Angola at the Turn of the Eighteenth Century

Dissertação apresentada para cumprimento dos requisitos necessários à obtenção do grau de Mestre em História Moderna e dos Descobrimentos

A study of bacterial contamination of rattlesnake venom

The authors studied the bacterial contamination of rattlesnake venom isolated from snakes in captivity and wild snakes caught recently. The captive snakes showed a relatively high incidence of bacterial contamination of their venom.

Bacterial peptidoglycan biosynthesis and recognition by the innate immune system

Dissertation presented to obtain the Ph.D degree in Biology

Enterococcus faecalis V583 prophages: Dynamic interactions and contribution to bacterial pathogenic traits

Dissertation presented to obtain the Ph.D degree in Biology.

Production of bacterial biopolymers from industrial fat-containing wastes

Dissertation presented in partial fulfilment of the Requirements for the Degree of Master in Biotechnology

Dissecting the function of the SpoIIIJ and YqjG membrane protein insertases during bacterial spore development

Dissertation presented to obtain the Ph.D degree in Biology, Microbial Biology

Assembly and function of a protein cross-linking enzyme during bacterial spore morphogenesis

Sporulation in Bacillus subtilis culminates with the formation of a dormant endospore. The endospore (or spore) is one of the most resilient cell types known and can remain viable in the environment for extended periods of time. Contributing to the spore’s resistance and its ability to interact with and monitor its immediate environment is the coat, the outermost layer of B. subtilis spores. The coat is composed by over 70 different proteins, which are produced at different stages in sporulation and orderly assembled around the developing spore.(...)

Characterization and regulation of a bacterial sugar phosphatase of the HAD superfamily, AraL, from Bacillus subtilis.

AraL from Bacillus subtilis is a member of the ubiquitous haloalkanoate dehalogenase, HAD, superfamily. The araL gene has been cloned, over-expressed in Escherichia coli and its product purified to homogeneity. The enzyme displays phosphatase activity, which is optimal at neutral pH (7.0) and 65 °C. Substrate screening and kinetic analysis showed AraL to have low specificity and catalytic activity towards several sugar phosphates, which are metabolic intermediates of the glycolytic and pentose phosphate pathways. Based on substrate specificity and gene context within the arabinose metabolic operon, a putative physiological role of AraL in detoxification of accidental accumulation of phosphorylated metabolites has been proposed. The ability of AraL to catabolise several related secondary metabolites requires regulation at the genetic level. Here, by site- directed mutagenesis, we show that AraL production is regulated by a structure in the translation initiation region of the mRNA, which most probably blocks access to the ribosome-binding site, preventing protein synthesis. Members of HAD subfamily IIA and IIB are characterised by a broad-range and overlapping specificity that anticipated the need for regulation at the genetic level. In this study we provide evidence for the existence of a genetic regulatory mechanism controlling AraL production.

Epidemiological profile of acute bacterial meningitis in the state of Rio Grande do Norte, Brazil

INTRODUCTION: Acute bacterial meningitis (ABM) remains a public health problem in Brazil. To evaluate the epidemiology of ABM cases at Giselda Trigueiro Hospital, Rio Grande do Norte, a descriptive retrospective survey was conducted covering 2005 to 2008. METHODS: Clinical and laboratory data were collected from the epidemiology department of the hospital and analyzed. RESULTS: Out of 168 ABM cases, 24.4%, 10.7%, and 2.4% were, respectively, caused by Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenza b, and 5.4% by other bacteria. The mean age was 22.48 ± 18.7 years old. CONCLUSIONS: Streptococcus pneumoniae was the main causative pathogen in the young urban population.

Manipulation of host cell functions by Salmonella: the role of the bacterial effector protein SteA

Salmonella enterica serovars are Gram-negative facultative intracellular bacterial pathogens that infect a wide variety of animals. Salmonella infections are common in humans, causing usually typhoid fever and gastrointestinal diseases. Salmonella enterica serovar Typhimurium (S. Typhimurium), which is a leading cause of human gastroenteritis, has been extensively used to study the molecular pathogenesis of Salmonella, because of the availability of sophisticated genetic tools, and of suitable animal and tissue culture models mimicking different aspects of Salmonella infections.(...)

Relationship between antibiotic consumption, oropharyngeal colonization, and ventilator-associated pneumonia by Staphylococcus aureus in an intensive care unit of a Brazilian teaching hospital

INTRODUCTION: his study evaluated the consumption of major classes of antibiotics, the colonization of the oropharynx of patients on mechanical ventilation, and the risk of ventilator-associated pneumonia (VAP) caused by Staphylococcus aureus in an intensive care unit for adults. METHODS: A case-control study was carried out using colonized patients (cases) by oxacillin-resistant S. aureus (ORSA) and (controls) oxacillin-sensitive S. aureus (OSSA) from May 2009 to August 2010. The occurrence of VAP by S. aureus was also evaluated in the same period. Antibiotic consumption was expressed as the number of defined daily doses (DDD)/1,000 patient-days for glycopeptides, carbapenems, and extended-spectrum cephalosporins. RESULTS: Three hundred forty-six (56.1%) patients underwent mechanical ventilation with a frequency of oropharyngeal colonization of 36.4%, corresponding to 63.5% for ORSA and 36.5% for OSSA. The risk of illness for this organism was significant (p<0.05), regardless of whether colonization/infection was by ORSA or OSSA. The consumption of antibiotics was high, mainly for broad-spectrum cephalosporins (551.26 DDDs/1,000 patient-days). The high density of use of glycopeptides (269.56 DDDs/1,000 patient-days) was related to colonization by ORSA (Pearson r=0.57/p=0.02). Additionally, age >60 years, previous antibiotic therapy, and previous use of carbapenems were statistically significant by multivariate analysis. CONCLUSIONS: There was a significant relationship between the colonization of the oropharyngeal mucosa and the risk of VAP by both phenotypes. The use of glycopeptides was related to colonization by ORSA.

Evaluation of bacterial growth inhibition by mercaptopropionic acid in metallo-β-lactamase detection on multidrug-resistant Acinetobacter baumannii

INTRODUCTION: Metallo-β-lactamase (MBL) has been reported all over the world. METHODS: The inhibitory effect of mercaptopropionic acid (MPA) on bacterial growth was evaluated by comparison between disk diffusion and broth dilution methodology with determination of the minimum inhibitory concentration (MIC) for multidrug-resistant Acinetobacter baumanni strains. RESULTS: MPA significantly inhibited growth of the strains. CONCLUSIONS: The use of MPA can affect the results in phenotypic methods of MBL detection.

Bacterial meningitis and living conditions

INTRODUCTION: Bacterial meningitis has great social relevance due to its ability to produce sequelae and cause death. It is most frequently found in developing countries, especially among children. Meningococcal meningitis occurs at a high frequency in populations with poor living conditions. This study describes the temporal evolution of bacterial meningitis in Salvador, Brazil, 1995-2009, and verifies the association between its spatial variation and the living conditions of the population. METHODS: This was an ecological study in which the areas of information were classified by an index of living conditions. It examined fluctuations using a trend curve, and the relationship between this index and the spatial distribution of meningitis was verified using simple linear regression. RESULTS: From 1995-2009, there were 3,456 confirmed cases of bacterial meningitis in Salvador. We observed a downward trend during this period, with a yearly incidence of 9.1 cases/100,000 population and fatality of 16.7%. Children aged <5 years old and male were more affected. There was no significant spatial autocorrelation or pattern in the spatial distribution of the disease. The areas with the worst living conditions had higher fatality from meningococcal disease (β = 0.0078117, p < 0.005). CONCLUSIONS: Bacterial meningitis reaches all social strata; however, areas with poor living conditions have a greater proportion of cases that progress to death. This finding reflects the difficulties for ready access and poor quality of medical care faced by these populations.