Resistencia bacteriana a los B-lactámicos en Venezuela / Bacter resistance to the betalactms antibiotics in Venezuela

En este trabajo se évalua el problema de la resistencia bacteriana a los antibióticos betalactamicos en venezuela. Se presentan los datos de resistencia bacteriana de varios hospitales venezolanos desde 1988 hasta 1992. Se analizan los resultados de las siguientes bacterias: Staphylococcus aureus, Staphylococus epidermidis, Enterococus faecalis, Escherichia coli, Klebsiella pneumoniae, Enterobacter aerogenes, Enterobacter cloacae, Proteus mirabilis, Proteus vulgaris, Salmonella sp., Shigella sp., Pseudomonas aeruginosa, Streptococus pneumoniae, Neisseria gonorrhoeae y Neisseria meningitidis

Comportamiento de strectococcus mutans bajo exposición prolongada a xilitol, sin recultivo / Behavior of streptococcus mutans by prolonged exposition to xylitol, wi-thout recultures

Estudios previos realizados en nuestro laboratortio demostraron que Streptococcus mutans, bacteria oral cariogénica, no metaboliza xilitol-polialcohol considerado anticariogénico aún después de un período de 10 meses de exposición al poliol, durante el cual la bacteria fue transferida mensualmente a medio fresco. Dado el riesgo potencial de adaptación, común en las bacterias, se estudió el comportamiento de Streptococcus mutans (Cepa 1161, Ingbritt) expuesto al poliol durante 7 meses, sin transferencia a nuevo medio. Las células bacterianas se mantuvieron en tripticasa soya (TS), sin glucosa, al cual se la adicionó xilitol (0.25 g/100 ml) y en el mismo medio sin carbohidrato. Después de 7 meses, las células fueron transferidas mensualmente a medio fresco hasta completar 14 meses. El control estuvo representado por células de Streptococcus mutans cultivadas en Ts con glucosa (0.25 g/100 ml). El crecimiento bacteriano en presencia de xilitol fue 63-78 por ciento más bajo que el observado en el control. Este mismo patrón se encontró en los cultivos que no contenian carbohidrato. El pH del medio durante el crecimiento se mantuvo por encima de 6.00, tanto en los cultivos que contenian xilitol como en aquellos que no contenian carbohidrato, mientras que en el control el pH final fue muy bajo (4.69 ñ 0.12). Las células bacterianas transferidas a TS con glucosa, exhibieron un patrón de crecimiento equivalente al observado en el control. Ningún cultivo fermentó xilitol; el pH del medio de fermentación permaneció alrededor de 6.00. No se observó consumo de 14C(U)-xilitol y la actividad de la enzima xilitol dehidrogenasa no pudo ser detectada con los procedimientos experimentales usados. El presente trabajo ratificó que Streptococcus mutans no tiene habilidad para metabolizar xilitol, aún después de períodos prolongados de exposición al azúcar-alcohol. Así mismo, demostró que el xilitol puede ser considerado una sustancia inerte para las células de Streptococcus mutans, las cuales se mantuvieron viables durante 14 meses en presencia del poliol, comportamiento equivalente al observado cuando el medio de cultivo no contenia carbohidrato

El fenómeno de swarming y otros tipos de desplazamiento bacteriano / Swarming phenomenom and other types of bacterial displacement

Algunas bacterias exhiben diversos tipos de desplazamiento sobre los medios de cultivo sólidos, lo que se pone en evidencia por la presencia de velos o películas de crecimiento en el entorno de las colonias. El fenómeno más conocido de éstos es el de "swarming", observado en Proteus spp., en el cual las bacterias sufren una transfiguración importante convirtiéndose en formas filamentosas hiperflageladas. Sin embargo, otros tipos de desplazamiento que se presentaron son "swimming", "twiching", "gliding", "sliding" y "darting", cuyas características más notorias se describen en este artículo.

Ultra-estrutura de bactérias periodontopatogênicas / Ultrastructure of pathogenic bacteria in periodontal tissue

É objetivo deste estudo, analisar a ultra-estrutura da Porphyromonas gingivalis, Prevotella intermedia e do Actinobacillus actinomycetemcomitans pelas técnicas mais atuais de microscopia eletrônica, dando ênfase às estruturas de superfície e às diferenças entre os microorganismos. Os resultados mostraram que os três microorganismos estudados apresentaram estrutura típica de parede celular de bactérias Gram-negativas. Também foram encontradas vesículas de membrana externa no meio intercelular das três bactérias estudadas

Effect of source and level of supplemental fat on total and ruminal organic matter and nitrogen digestion in dairy cows.

Effects of fat supplementation for dairy rations on digestibility and ruminal digestion were studied in four cows receiving a control diet (hay-concentrate) or this diet supplemented with 5 or 10% rapeseed oil or 10% tallow, according to a Latin square design. Neither total digestibility of DM, OM, and crude fiber nor ruminal OM digestibility was modified by lipid supply. Microbial N flow to the duodenum was calculated for solid-adherent bacteria and liquid-associated bacteria, using the turnover rate of liquid phase, the ruminal pools of bacteria and their concentrations in RNA, and diaminopimelic acid. Flows of total and bacterial duodenal OM and N did not depend on the fat content of the diet. In sacco ruminal degradation of DM was lower for a diet supplemented with 10% rapessed oil than for the control diet. The addition of rapeseed oil resulted in decreased acetate and increased propionate proportions in ruminal VFA and decreased ruminal ammonia after feeding. This trial showed that modifications in ruminal digestion did not have any negative consequence on OM degradation and did not modify ruminal N digestion.

Direct determination of phospholipid structures in microorganisms by fast atom bombardment triple quadrupole mass spectrometry.

When phospholipids ionized by fast atom bombardment undergo collisionally induced dissociation (CID), they cleave at specific bonds between the functional groups contained on the lipid. These cleavages are common to all classes of phospholipids. By taking advantage of this fact, a general scheme has been developed that uses a triple-quadrupole mass spectrometer to rapidly characterize the phospholipid content and structures present in crude lipid extracts. This scheme is based on fast atom bombardment ionization of a crude lipid extract and on the combination of positive-ion neutral-loss and parent scans and negative-ion daughter scans. Neutral-loss and parent scans provide independent diagnostic mass spectra for each of many specific phospholipid classes, while daughter scans provide the emperical formulas and positions of the fatty acyl constituents on each phospholipid. An automated tandem mass spectrometry (MS/MS) instrument can perform an extensive phospholipid screening on a single sample. A useful mass profile of the phosphatidylethanolamine species present in a 1-pg sample of mixed phospholipids (equivalent to ten Escherichia coli cells) has been obtained. The spectra are reproducible and proportional to concentration over at least the five-logarithm range of cell concentrations studied. A rapid extraction procedure combined with the automated instrument control program produces profiles of the phospholipid classes, along with fatty acyl empirical formulas and position information, on selected phospholipid species, in a few minutes, from a single sample.

The distribution of soluble metallo-redox proteins in purple phototrophic bacteria.

A comparison is made of types and distribution of cytochromes and certain ferredoxins (HiPIP) among photosynthetic bacteria. These are subdivided as to the type of reaction center each species is believed to contain. The proteins listed are assumed to be of periplasmic origin. Interrelationships suggested by the comparison are discussed.

Distribution of naturally occurring quinones.

Angiosperms, fungi (including lichens), and bacteria are the main sources of natural quinones. Small numbers are present in algae, ferns, conifers, sponges, echinoderms, other marine animals, and arthropods. In angiosperms quinones have some chemotaxonomic value at the genus and family level but more surveys are required.

Ultrastructural and electron spectroscopic analyses of cyanobacteria and bacteria.

The extracellular sheath material and some intracellular cell components of cyanobacteria and phosphate-accumulating sewage bacteria were analysed by electron spectroscopic imaging (ESI) and electron energy-loss spectroscopy (EELS). The specimens were embedded in water-soluble Nanoplast resin without any previous fixation and ultrathin sections were examined in a Zeiss CEM 902 microscope. A high sulphur content was detected in the inner sheath of the cyanobacterium Gloeothece. The elemental composition of some cell components and inclusion bodies, such as carboxysomes and cyanophycin, was determined by ESI and EELS. In addition, the phosphate content in specific granules of phosphate-accumulating sewage bacteria was estimated by EELS and nuclear magnetic resonance spectroscopy.

Impact of dietary cereal on nutrient absorption and fecal nitrogen loss in formula-fed infants.

STUDY OBJECTIVE: To determine the capacity of infants to digest and absorb rice cereal and to determine the effect of cereal feeding on total energy and nitrogen absorption. SETTING: Subject's residences and the Texas Children's Hospital Clinical Research Center, Houston. PATIENTS: Eight healthy 1-month-old bottle-fed infants. INTERVENTIONS: Infants were fed their usual formula for 3 days. For the subsequent 6 days, they received 4 gm of rice cereal, labeled with carbon 13, per 30 ml of the formula. MEASUREMENTS AND MAIN RESULTS: Fecal balance studies were performed for a 72-hour period while the infants received only formula and again during the last 3 days of cereal feeding. Breath samples for hydrogen measurement were collected before and after the cereal feeding. Nutrient intake was measured and stools were analyzed for 13C abundance, energy, nitrogen, fiber content, and bacterial mass. Cereal absorption was 88 +/- 9% (mean +/- SD). Despite a significant increase in energy and nitrogen intake from cereal feeding, the coefficient of absorption fell (energy: 97% to 90%, p = 0.048; nitrogen: 94% to 74%, p = 0.009). Fecal dry weight increased after the cereal feeding (p = 0.004), primarily as a result of a sevenfold increase in fecal bacterial mass (p = 0.002). Fecal nitrogen increased primarily because of incorporation of nitrogen into bacteria. No differences were detected in breath hydrogen as a consequence of formula feeding versus formula-cereal feeding. CONCLUSIONS: Although cereal was relatively well-absorbed in this group of infants and increased their intakes of energy and nitrogen, it did not increase the coefficients of energy and nitrogen absorption. Cereal feeding increased fecal bacterial mass and bacterial nitrogen.

Activation of the prophenoloxidase cascade and initiation of nodule formation in locusts by bacterial lipopolysaccharides.

The activation of the prophenoloxidase (proPO) system of the locusts, Schistocerca gregaria and Locusta migratoria, by several bacterial lipopolysaccharides (LPS) is described. Activation of proPO by LPS occurred only in the presence of whole blood homogenates and not with hemocyte lysate preparations alone. Levels of phenoloxidase generated by the different LPSs in vitro were also correlated with numbers of nodules formed in vivo by injection of these LPSs. This further strengthens the evidence for the involvement of proPO activation in the insect cellular defenses. Finally, the wisdom in using anticoagulants in order to stabilize fragile hemocytes in studies on the proPO system is discussed.

Microbial lipids and stable foam formation in the activated sludge process.

The presence of fats and oils in sewage has been related to the formation of stable foams in activated sludge treatment systems. Foam forming microbes can utilise and, in some cases, store lipid substrates. Since surface lipids would confer the hydrophobicity necessary for flotation on the sludge biomass, the extractable lipids in foaming and non-foaming biomass samples were examined. Both pure mono-cultures and sludge samples were used. The results showed that, whilst there were some differences in the lipid profiles of the mono-cultures, the different sludge types did not show any significant pattern or variation which could be used as a lipid-based explanation for foam formation.

Applications of gas chromatography-mass spectrometry in the study of androgen and odorous 16-androstene metabolism by human axillary bacteria.

The known involvement of axillary microflora with under-arm odour (UAO) production led us to determine whether the odorous 16-androstene steroids are formed in the axilla by bacterial metabolism of an odourless precursor such as testosterone. Axillary bacteria from 34 men were selectively cultured for aerobic coryneform bacteria (ACB), Micrococcaceae and propionibacteria. Overnight suspensions of bacteria were incubated separately at 37 degrees C for two weeks with radiolabelled testosterone plus unlabelled testosterone (0.5 mg) and 0.5-mg quantities of 4,16-androstadien-3-one (androstadienone) and 5,16-androstadien-3 beta-ol (androstadienol). After extraction and purification by Sep-Pak cartridges and thin-layer chromatography, the eluted steroids were derivatised as the pentafluorobenzyl oximes (PFBO) and tert.-butyl dimethylsilyl (TBDMS) ethers. Saturated analogues were used as internal standards. Selected-ion monitoring electron-impact mass spectrometry was performed at the m/z corresponding to the M+.ion for the PFBO derivatives and the [M - 57]+ ion for the TBDMS ethers. Only ACB produced classical musk-like UAO (UAO + ve) in an in vitro odour-producing system with 29% being UAO -ve. ACB (UAO +ve) metabolised far more (p = 0.001) testosterone than ACB (UAO -ve), the principal metabolites being 5 alpha(beta)-dihydrotestosterone, 5 alpha(beta)-androstane-3,17-dione and 4-androstene-3,17-dione (4-androstenedione). No non-polar 16-androstenes were formed. Micrococcus luteus (ten strains) metabolised testosterone to 4-androstenedione only; propionibacterium spp. did not metabolise testosterone at all. However, incubation of 16-androstenes with ACB gave evidence for 4-ene-5 alpha(beta)-reduction, 3 alpha(beta)-oxido-reduction and epimerisation. In general the direction of transformations favoured formation of the more odorous 5 alpha-androst-16-en-3-one (5 alpha-androstenone) and 5 alpha-androst-16-en-3 alpha-ol (3 alpha-androstenol) from less odorous steroids. Such transformations, in vivo, would not require de novo synthesis of 5 alpha-androstenone or 3 alpha-androstenol and would be consistent with utilisation by ACB of 16-androstenes already present in small quantities in fresh apocrine secretions, which are odourless, to produce a more powerfully smelling mixture on the axillary skin surface.

Near-infrared spectrometry of microorganisms in liquid pharmaceuticals.

Biotechnology and pharmaceutical research have created a number of new and potentially life-saving drugs. Many of these drugs are formulated as injectable products. Some drug products do not survive autoclaving or other means of terminal sterilization. An aseptic filling process is typically used to sterilize such products, but it is less reliable than autoclaving, making detection of unsterile units even more essential. Invasive microbiological methods and turbidimetry are currently employed as inspection techniques. These processes are time-consuming, destroy product, and may not detect low levels of contamination. Near-IR light scattering is proposed as a new method of determining low levels of contamination noninvasively and nondestructively. The method is used successfully in the current study to detect contamination by a species of yeast, mold, and bacteria in intact plastic infusion bags at levels as low as three colony-forming units per milliliter for yeast. By use of the near-IR method, each injectable unit can be evaluated with its integrity maintained, allowing the product to be dispensed or evaluated by another analytical method.

Characterization of underivatized lipid biomarkers from microorganisms with pyrolysis short-column gas chromatography/ion trap mass spectrometry.

A microvolume Curie-point pyrolysis short-column (5 m) gas chromatography/mass spectrometry (Py-GC/MS) procedure was developed for the characterization of various lipid moieties in microorganisms. High linear flow rates (approximately 175 cm/s) characterized the GC conditions in order to effect an efficient chromatographic transfer and elution of the underivatized diglycerides and monoglycerides, and small modifications were necessary to the ion trap MS system in order for it to accommodate the relatively high gas load. During a typical analysis run anhydrodiacylglycerides eluted within a 5-6-min time frame. Gram-positive bacilli and Gram-negative species were differentiated from each other by the pyrolysis patterns of their lipid components. In spite of the complexity of the analyte, a straightforward visual analysis was achieved with the aid of simple computerized data display procedures. These procedures included examination of (1) total ion current (TIC) profiles of the lipid region of the reconstructed chromatogram, (2) the integrated mass spectrum of this region, (3) selected reconstructed ion chromatograms (RICs), (4) RIC intensity distributions, and (5) corresponding mass spectra. An appealing aspect of the lipid data reduction procedure is that most of it can be accomplished visually without requiring computerized pattern recognition techniques.

Relationship of airborne microorganisms with the lung function and leucocyte levels of workers with a history of humidifier fever.

An influenza-like illness appeared recently among workers in a plant processing synthetic yarn. A humidifier, a cold-water spraying system, was the suspected cause. Lung function changes over the day and week and changes in blood leucocytes were studied among the workers from the suspected department and two reference populations. Exposure to colony-forming units of bacteria and fungi and to endotoxins was also monitored. The workers from the suspected department had statistically significantly lower lung functions on the first workday of the week than the referents. Their blood leucocytes were also raised statistically significantly. The exposure to fungi, bacteria, and endotoxins differed significantly between the various departments, but the measured levels were low. It was concluded that the observed effects were suggestive of a "Monday morning fever" type of reaction and that adverse effects occurred at exposure levels lower than those found to date in the literature.

A new and rapid method for the assay of bacterial fatty acids using high resolution capillary gas chromatography and trimethylsulfonium hydroxide.

Gas-liquid chromatography of cellular fatty acids is a useful tool for the identification of bacteria. Derivatization of bacterial fatty acids to methyl esters by conventional techniques is usually time-consuming and complicated. A new one-step technique using trimethyl-sulfonium hydroxide allows the direct formation of fatty acid methyl esters within 1-2 min. Some random examples of profiles demonstrate that straight, branched, saturated, unsaturated, hydroxy and cyclopropyl fatty acids match conventional preparations well. The method is a very sensitive one, since only a few colonies are sufficient for preparation of fatty acid methyl esters.

Interlaboratory variation in a diaminopimelic acid assay: influence on estimated duodenal bacterial nitrogen flow.

Samples of ruminal bacteria and duodenal digesta were collected from two dairy cows fed a 65% forage diet. Samples were sent blind to four laboratories for diaminopimelic acid analysis. Analyzed values differed among laboratories within sample type, and concentrations ranked as follows: laboratory D greater than laboratory A greater than laboratory B greater than laboratory C. Consideration of differences in actual procedures used among laboratories resulted in several hypotheses to explain some of the interlaboratory variation. Using diaminopimelic acid values from each laboratory to estimate duodenal bacterial nitrogen flow showed that laboratory D estimated a 17% higher flow than the average for laboratories A, B, and C, which were similar.