Recycling old screen-printed electrodes with newly designed plastic antibodies on the wall of carbon nanotubes as sensory element for in situ detection of bacterial toxins in water

Using low cost portable devices that enable a single analytical step for screening environmental contaminants is today a demanding issue. This concept is here tried out by recycling screen-printed electrodes that were to be disposed of and by choosing as sensory element a low cost material offering specific response for an environmental contaminant. Microcystins (MCs) were used as target analyte, for being dangerous toxins produced by cyanobacteria released into water bodies. The sensory element was a plastic antibody designed by surface imprinting with carefully selected monomers to ensure a specific response. These were designed on the wall of carbon nanotubes, taking advantage of their exceptional electrical properties. The stereochemical ability of the sensory material to detect MCs was checked by preparing blank materials where the imprinting stage was made without the template molecule. The novel sensory material for MCs was introduced in a polymeric matrix and evaluated against potentiometric measurements. Nernstian response was observed from 7.24 × 10−10 to 1.28 × 10−9 M in buffer solution (10 mM HEPES, 150 mM NaCl, pH 6.6), with average slopes of −62 mVdecade−1 and detection capabilities below 1 nM. The blank materials were unable to provide a linear response against log(concentration), showing only a slight potential change towards more positive potentials with increasing concentrations (while that ofthe plastic antibodies moved to more negative values), with a maximum rate of +33 mVdecade−1. The sensors presented good selectivity towards sulphate, iron and ammonium ions, and also chloroform and tetrachloroethylene (TCE) and fast response (<20 s). This concept was successfully tested on the analysis of spiked environmental water samples. The sensors were further applied onto recycled chips, comprehending one site for the reference electrode and two sites for different selective membranes, in a biparametric approach for “in situ” analysis.

Seroprevalence of selected viral, bacterial and parasitic infections among inpatients of a public psychiatric hospital of Mexico

We sought to determine the frequency of serological markers of selected infections in a population of psychiatric patients in Durango City, Mexico, and to determine whether there are any epidemiological characteristics of the subjects associated with the infections. One hundred and five inpatients of a public psychiatric hospital of Durango were examined for HBsAg, anti-HCV antibodies, anti-HIV antibodies, anti-Brucella antibodies, rapid plasma reagin and anti-Cysticercus antibodies by commercially available assays. Anti-Cysticercus antibodies were confirmed by Western blot and HBsAg by neutralization assay. Epidemiological data from each participant were also obtained. Seroprevalences of HBsAg, anti-HCV, anti-HIV, anti-Brucella, rapid plasma reagin and anti-Cysticercus antibodies found were 0.0%, 4.8%, 0.9%, 0.0%, 1.9%, and 0.9%, respectively. Overall, 9 (8.6%) inpatients showed seropositivity to any infection marker. We concluded that our psychiatric inpatients have serological evidence of a number of infections. HCV is an important pathogen among our psychiatric inpatients. Health care strategies for prevention and control of infections in Mexican psychiatric patients should be considered.

Perinatal Bacterial Infection: Screenning of Vertical Transmitted Infections

Perinatal bacterial infection may be caused by any microorganism colonizing the vaginal tract. Neonatologists and paediatricians are especially concerned about group B Stretpococcus (GBS). However, Enterobactereacea, mainly E.coli and Proteus, are also responsible for infection. GBS screening may be accomplished in over 90% of pregnant women. In our maternity in 2007-2008, 85% of the mothers had been screened. Screening and prophylaxis were responsible for a decreasing incidence of neonatal infection - from 0.6/1000 to 0.15/1000 live births in Portugal, from 2002 to 2007. However there are some difficulties related to screening. In the second Portuguese study 16/57 NB with early-onset infection (28%) were born to “negative” mothers. Several factors illustrate how difficult is to draw national screening policies: a wide range of carrier’s state rate throughout a country - in Portugal from 12% to 30%. The success of any screening policy may also be affected by additional technical and organizational problems. In countries where home delivery is a tradition or a trend intrapartum GBS prophylaxis requires a very well organized assistance.. Moreover factors usually accepted as protective are not so effective. In the Portuguese study 24/57 infected newborns (42%) were delivery by caesarean section. Another subject deals with the workload in the postnatal ward generated by deficient compliance to the guidelines a problem not confirm by a study of our group. Decreasing the importance of GBS, highlight the importance of E. coli in perinatal infection. From the 16 340 registrations of the National Registry 1676 were newborns with mother-related infection. Applying the same reasoning to E.coli as to GBS and Listeria monocytogenes – that is considering all of them are of maternal origin - 6.7% of these infections were due to E. coli, 4.6% to SGB and 0.5% to Listeria monocytogenes. In conclusion screening and prophylaxis may be not the best way to prevent all GBS neonatal infections but by now it is the only available procedure. The other bacteria continue to demand a high suspicion level and immediate intervention.

MOLECULAR TYPING OF Candida albicans ISOLATES FROM HOSPITALIZED PATIENTS

SUMMARYIntroduction: The majority of nosocomial fungal infections are caused by Candida spp. where C. albicans is the species most commonly identified. Molecular methods are important tools for assessing the origin of the yeasts isolated in hospitals.Methods: This is a study on the genetic profifiles of 39 nosocomial clinical isolates of C. albicans using two typing methods: random amplifified polymorphic DNA (RAPD) and microsatellite, two different primers for each technique were used.Results: RAPD provided 10 and 11 different profiles with values for SAB of 0.84 ± 0.126 and 0.88 ± 0.08 for primers M2 and P4, respectively. Microsatellite using two markers, CDC3 and HIS3, allowed the observation of six and seven different alleles, respectively, with combined discriminatory power of 0.91.Conclusions: Although genetic variability is clear, it was possible to identify high similarity, suggesting a common origin for at least a part of isolates. It is important to emphasize that common origin was proven from yeasts isolated from colonization (urine, catheter or endotracheal secretions) and blood culture from the same patient, indicating that the candidemia must have started from a site of colonization. The combination of RAPD and microsatellite provides a quick and efficient analysis for investigation of similarity among nosocomial isolates of C. albicans.

MOLECULAR TYPING OF Giardia duodenalisISOLATES FROM NONHUMAN PRIMATES HOUSED IN A BRAZILIAN ZOO

Giardia infections in captive nonhuman primates (NHP) housed at a Brazilian zoo were investigated in order to address their zoonotic potential. Fresh fecal samples were collected from the floors of 22 enclosures where 47 primates of 18 different species were housed. The diagnosis of intestinal parasites after concentration by sedimentation and flotation methods revealed the following parasites and their frequencies: Giardia (18%); Entamoebaspp. (18%); Endolimax nana(4.5%); Iodamoeba spp. (4.5%); Oxyurid (4.5%) and Strongylid (4.5%). Genomic DNA extracted from all samples was processed by PCR methods in order to amplify fragments of gdh and tpi genes of Giardia. Amplicons were obtained from samples of Ateles belzebuth, Alouatta caraya, Alouatta fusca and Alouatta seniculus. Clear sequences were only obtained for the isolates from Ateles belzebuth (BA1), Alouatta fusca(BA2) and Alouatta caraya (BA3). According to the phenetic analyses of these sequences, all were classified as assemblage A. For the tpi gene, all three isolates were grouped into sub-assemblage AII (BA1, BA2 and BA3) whereas for the gdh gene, only BA3 was sub-assemblage AII, and the BA1 and BA2 were sub-assemblage AI. Considering the zoonotic potential of the assemblage A, and that the animals of the present study show no clinical signs of infection, the data obtained here stresses that regular coproparasitological surveys are necessary to implement preventive measures and safeguard the health of the captive animals, of their caretakers and of people visiting the zoological gardens.

Studies on BolA and ribonuclease R: two important factors in the control of bacterial gene expression

Dissertation presented to obtain the Ph.D degree in Biology

Epidemiological studies of Streptococcus pneumoniae carriage in the post-vaccination era among two risk groups: children and the elderly

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

PREVALENCE OF BACTERIAL RESISTANCE IN HOSPITALIZED CIRRHOTIC PATIENTS IN SOUTHERN BRAZIL: A NEW CHALLENGE

Background & Aims: An increased frequency of infections by multiresistant bacteria has been described in hospitalized patients. The aim of this study was to evaluate the bacterial resistance profile in cirrhotic patients. Methods: This is a retrospective observational study. We assessed the antimicrobial susceptibility of 5,839 bacterial isolates from patients with and without cirrhosis. Regarding the multidrug resistance, we evaluated 4,505 bacterial isolates from 2,180 patients. Results: Two hundred and fifty-one patients had cirrhosis (mean age 57.6 ± 11 years; 61.8% were male, 47.8% of cases associated with hepatitis C virus). Of the isolates of patients with and without cirrhosis, 174/464 (37.5%) and 1,783/4,041 (44.1%) were multiresistant, respectively (p = 0.007). E. coli was the most common multiresistant bacteria in both groups. Approximately 20% of E. coli and Klebsiella sp. isolates were ESBL-producers and 44% of S. aureus isolates were methicillin-resistant in cirrhotic patients. In cirrhotic patients admitted to the emergency department, hospital ward, and intensive care unit, 28.3%, 50% and 40% had multiresistant isolates, respectively. In patients with and without cirrhosis, 36.2% and 33.5% of isolates were resistant to third-generation cephalosporins, respectively. Conclusions: The empirical treatment of infections in hospitalized patients using broad-spectrum antibiotics should consider the observed pattern of bacterial resistance.

A copper protein and a cytochrome bind at the same site on bacterial cytochrome c peroxidase

Biochemistry, 2004, 43 (46), pp 14566–14576 DOI: 10.1021/bi0485833

Engineering of bacterial exopolysaccharides: from synthesis to properties

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

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.