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PubMed1974

Radiation genetics in microorganisms and evolutionary considerations.

Recent knowledge of UV-resistance mechanisms in microorganisms is reviewed in perspective, with emphasis on E. coli. Dark-repair genes are classified into "excision" and "tolerance" (ability to produce a normal copy of DNA from damaged DNA). The phenotype of DNA repair is rather common among the microorganisms compared, and yet their molecular mechanisms are not universal. In contrast, DNA photoreactivation is the simplest and the most general among these three repair systems. It is proposed that DNA repair mechanisms evolved in the order: photoreactivation, excision repair, and tolerance repair. The UV protective capacity and light-inducible RNA photoreactivation possessed by some plant viruses are interpreted to be the result of solar UV selection during a rather recent era of evolution.

Biological Evolution↗
PubMed1993

A prospective study of the catheter hub as the portal of entry for microorganisms causing catheter-related sepsis in neonates.

The hypothesis that catheter-related sepsis (CRS) may be preceded by contamination of the catheter hub was tested in neonates with central venous catheters. Cultures of the catheter hub were obtained three times per week. One hundred thirteen catheters were placed in 88 patients. Of 35 episodes of sepsis, 28 were catheter-related, for a catheter sepsis rate of 1.03/100 catheter-days. CRS occurred in 26 (23%) of 113 catheters. In 10 of 28 episodes, the infecting microorganism was cultured from the hub before its culture from blood obtained at the time of clinical sepsis. In an additional 5 cases, a culture of the catheter hub at the time of clinical sepsis yielded the same isolate as the blood culture. Thus, 54% of episodes of CRS were preceded by or coincided with contamination of the hub. The catheter hub may be a major portal of entry for microorganisms causing sepsis in a neonatal intensive care unit.

Bacteremia↗
PubMed2000

Linoleic acid conjugation by human intestinal microorganisms is inhibited by glucose and other substrates in vitro and in gnotobiotic rats.

The anticarcinogen conjugated linoleic acid (CLA) is a product of bacterial activity that isomerizes linoleic acid (LA) in the rumen of herbivores. Therefore, fatty dairy products in the human diet are enriched with CLA. Although bacteria capable of in vitro LA conjugation were detected in the human intestinal tract, CLA synthesis from dietary sunflower seed oil was not observed in gnotobiotic rats associated with these intestinal bacteria. The objective of the study was to investigate variables that affect LA conjugation. In vitro, LA conjugation was strongly inhibited by glucose and other substrates. Concentrations of 1.5 mmol glucose/L inhibited LA conjugation by 50%. Methyl-alpha-D-glucoside was a less effective inhibitor than glucose, and 2-deoxy-D-glucose did not inhibit LA conjugation at all. To analyze the concentration of carbohydrates in intestinal contents, the LA-conjugating bacterial mixed culture and human fecal microorganisms were introduced into germ-free rats. Samples of feces and cecum and colon contents of both groups exhibited in vitro LA-conjugating activity. Rats associated with human intestinal microorganisms contained 5.7 +/- 1. 3 mmol glucose/L in the cecal contents and 6.6 +/- 1.0 mmol glucose/L in the colonic contents. Rats associated with CLA-producing bacterial culture contained 3.4 +/- 1.3 mmol glucose/L in the cecal contents and 4.2 +/- 1.0 mmol glucose/L in the colonic contents. These values are within a range that may explain the observed inhibition of LA conjugation in vivo.

Animals↗
PubMed2003

Microorganism-induced skin disease in workers exposed to metalworking fluids.

BACKGROUND: An outbreak of skin disorders among workers potentially exposed to metalworking fluids prompted the present study. Few studies have described skin disorders associated with microbe-contaminated metalworking fluids. METHODS: Samples of materials contaminated with metalworking fluids were obtained from two manufacturing facilities in Ohio. Pathogenic bacteria and yeasts, in concentrations sufficient to cause skin disease, were cultured from 9 of 12 (75%) sampled materials. RESULTS: Allergic patch testing of five affected people produced negative results for standard allergens, augmented by fluids and items from their workplace. This ruled out allergies as the cause of the skin disease. Improper handling and disposal of cotton gloves, inappropriate use of scouring pads and ineffective hand wiping were apparently responsible for the microbiological contamination. The hands and forearms were most commonly affected. CONCLUSION: Improper handling of soluble, synthetic and semi-synthetic metalworking fluids provides an excellent environment for the growth of a range of microorganisms, including bacteria and fungi. If allowed to grow because of poor occupational hygiene, these microorganisms can cause skin disorders among workers. Soiled protective clothing (gloves, coveralls and work boots) should be cleaned or discarded on a regular basis. When washing up, workers should not use metalworking fluids and items used to clean machinery.

Adult↗
PubMed1999

The use of poultry litter as co-substrate and source of inorganic nutrients and microorganisms for the ex situ biodegradation of petroleum compounds.

The purpose of this investigation was to determine the feasibility of utilizing poultry litter as a source of microorganisms, C co-substrate, N, and P to enhance the biodegradation of petroleum compounds in contaminated soil. An initial laboratory-scale study utilized soil contaminated with approximately 3,000 mg/kg (ppm) total petroleum hydrocarbons (TPHC) as diesel fuel. Biotreatment units, each containing 10 L of contaminated soil, were supplemented (0, 1, 10, and 20%, total weight basis) with broiler litter containing 3.65% N and 1.89% P. Petroleum-degrading microorganisms previously enriched from broiler and turkey litter were also inoculated into the litter-treated units. A significant first order rate of TPHC biodegradation was measured for all treatment units containing broiler litter (P < 0.05). Based on these results, a subsequent study was conducted at the site of a commercial facility permitted to treat soil (ex situ) contaminated with hazardous compounds. Soil treatment plots, each containing approximately 1 ton of soil contaminated with approximately 1,200 to 1,600 mg/kg diesel fuel were established. Each plot was replicated four times and the experiment was conducted for 35 d. Treatments were as follows: control, soil only; soil + commercial blend of bioremediation nutrients; soil + commercial fertilizer; soil + poultry litter (1% by volume); soil + poultry litter (10% by volume); soil + pelleted poultry litter (10% by volume). The results showed that the remediation of soil contaminated with petroleum compounds is significantly (P < 0.05) enhanced when supplemented with poultry litter (pelleted or nonpelleted) in concentrations of 10% soil volume. These results demonstrate the potential for a specialized market for the use of poultry litter.

Animals↗
PubMedDate not supplied

Septic arthritis of the sternoclavicular joint due to gram-positive microorganisms.

Infectious arthritis of the sternoclavicular (SC) joint is a known complication of intravenous drug abuse. Most reported cases have been caused by gram-negative microorganisms. Patients with this form of septic arthritis usually have protracted illnesses and require both medical and surgical, therapy. During 18 months we saw four cases of SC septic arthritis cause by gram-positive microorganisms. Three cases were related to heroin use and Staphylococcus aureus was the causative organisms. Streptococcus pneumoniae was isolated in the remaining patient. All patients had the abrupt onset of SC joint swelling and tenderness as the initial complaint and all responded favorably to appropriate intravenous drug therapy.

Adult↗
PubMed2003

How not to get bugged by bugs: mechanisms of cellular tolerance to microorganisms.

PURPOSE OF REVIEW: Advances in the characterization of the receptors and signaling pathways involved in the response to infection have led to a more detailed understanding of cellular tolerance to endotoxin and other microbial components. This review summarizes recent progress in the field, particularly in relation to the molecular mechanisms that underlie the development of tolerance to microorganisms. RECENT FINDINGS: The identification of Toll-like receptors as major sensors of microbial molecules has led to numerous studies of their function in tolerant cells. Decreased Toll-like receptor expression, altered interactions between the Toll-like receptors and intracellular signal transducers, and decreased expression or activity of downstream signaling molecules have all been implicated. Upregulation of specific proteins that inhibit Toll-like receptor signaling has also been described. Apart from these general mechanisms, special features of the intestinal microenvironment and its resident cells also contribute to making the gut hyporesponsive to microorganisms. SUMMARY: The application of gene knockout technology has highlighted the importance of macrophage tolerance in regulating innate immunity to microbial infection. Such studies have indicated that the failure of tolerance can lead to exaggerated inflammatory responses to intestinal bacteria, raising the possibility that defects in tolerance may be linked to conditions such as inflammatory bowel disease. Further characterization of this link will help in elucidating the pathogenesis of such conditions and in devising new approaches to treatment.

Journal Article↗
PubMed1997

Hypothesis--origin of the parietal cell: microorganism?

Parietal cells, which exist in the stomach and in Meckel's diverticulum of the ileum, secrete hydrochloric acid by means of H+,K(+)-ATPase (alpha- and beta-subunits) in the human body. Although parietal cells are generated from progenitor cells (stem cells), their lifespan (approximately 150-200 days) is distinctly longer than that of surface epithelial cells (4 days), which are also derived from stem cells. Microorganisms, including bacteria (both aerobic and anaerobic), are able to pump H+ out by means of H(+)-ATPase. Of interest is that 19% of the human H+,K(+)-ATPase (alpha-subunit) comprises amino acid residues identical to those of the H(+)-ATPase found in Neurospora crassa. In addition, the amino acid sequence in the ATP binding sites of animal Na+,K(+)-ATPase and yeast H(+)-ATPase with phosphorylated intermediates is highly conserved. These data appear to indicate that the parietal cell might have originated from a microorganism that was parabiosed in a separate origin, having digestive organs, that was later incorporated into a stem cell. Thereafter, the gene encoding H+,K(+)-ATPase, or those encoding GATA DNA binding proteins (transcriptional regulators of the gastric H+,K(+)-ATPase gene), or both were translocated into the nuclei, most probably with the aid of a virus and/or a transposon under unusual circumstances. This type of gene translocation most probably occurred during the Cambrian era when Prochordata and Chordata, which have no parietal cells, were abundant. This suggests that in the process of evolution, the stem cells in the digestive organs of the Cordata might have differentiated into two cell types, i.e., surface epithelial cells and parietal cells, before the appearance of fish (which possess parietal cells with H+,K(+)-ATPase).

Animals↗
PubMed1993

Microbial contamination of hydrophilic contact lenses: quantitation and identification of microorganisms associated with contact lenses while on the eye.

Previous studies have demonstrated the presence of microorganisms on hydrogel contact lenses under various usage conditions. We conducted this study to quantify and identify viable bacteria and fungi associated with hydrogel contact lenses while on the eye. We removed the lenses from patients' eyes using aseptic techniques and cultured them to identify loosely adherent, as well as lens bound, microorganisms. Lenses were vortexed in a transfer medium (thereafter called the lens extract) and the lenses were then incubated in an agar sandwich separately from the transfer medium. We cultured 108 lenses (82 daily wear and 26 extended wear) from 49 patients. Bacteria were cultured from 38% (41) of the lenses; for 31 of these 41 lenses bacteria were isolated only from the lens extracts (made by vortexing lenses in a transfer medium), suggesting a transient association with the lenses. No fungi were isolated. Counts of less than 10 colony forming units (CFU)/lens were observed on 89% of the lenses. Staphylococcus epidermidis were the most frequently isolated bacteria. A statistically significant relation was observed between increased CFU/lens and increased lens age for extended wear lenses (p = 0.028).

Adult↗
PubMed2001

Comparison of translocation of different types of microorganisms from the intestinal tract of burned mice.

The aim of this study was to compare the ability of various microorganisms to translocate from the intestine to the mesenteric lymph nodes (MLNs), liver, and spleen in a burned mouse model. Balb/c mice were gavaged with 1 x 10(9) or 1 x 10(10) of one of 11 different microorganisms. All animals were then given a 20% burn. Survival after 10 days showed no significant difference between any of the groups at the 10(10) dose. At the 10(9) dose, significantly higher survival rates were found in three of the 11 strains. Microbial translocation (gavage of 10(10) 111In-labeled organisms) and host's ability to kill translocated bacteria (viable bacteria in tissues) were measured followed by burn injury and sacrifice four hours later. Translocation and killing of Staphylococcus epidermidis and Escherichia coli was high in the MLNs compared with all other groups but translocation was lower to the liver. Klebsiella, Pseudomonas, and Serratia translocated more evenly to all the tissues. However, these groups showed very high clearance of bacteria in the liver and spleen except for Klebsiella and one strain of Pseudomonas in the spleen. Candida showed poor translocation to all of the tissues and high clearance. It is concluded that various strains of bacteria translocate from the intestine to a similar degree after injury, but the tissues to which they translocate and the rate at which they are killed are somewhat strain dependent.

Animals↗
PubMedDate not supplied

Stress as a determinant of saliva-mediated adherence and coadherence of oral and nonoral microorganisms.

OBJECTIVE: The mucosal secretory proteins, such as the salivary proteins, play a key role in the acquisition and regulation of the mucosal microflora. Most notably, some microorganisms utilize the host's secretory proteins to adhere to the mucosa; a first step in colonization and infection. The secretory proteins also influence colonization by affecting the binding among microorganisms, a process denoted as coadherence. Previously we reported that acute stressors cause specific changes in saliva composition. The present study investigated to what extent these changes influence saliva-mediated microbial adherence and coadherence (ex vivo). METHODS: Thirty-two male undergraduates provided unstimulated saliva before and during a control condition and two stressors: A memory test and a surgery video presentation. We used saliva-coated microplates to test the adherence of bacteria for which the oral cavity is either a natural reservoir (eg, viridans streptococci) or a portal of entry (eg, Helicobacter pylori). We also tested the saliva-mediated co-adherence between Streptococcus gordonii and the yeast Candida albicans. Correlation analyses were performed to determine the relationships between changes in microbial adherence and the concentrations of potential salivary ligands, viz. cystatin S, the mucins MUC5B and MUC7, S-IgA, lactoferrin, alpha-amylase, and total salivary protein. RESULTS: During the memory test, saliva-mediated adhesion of Streptococcus sanguis, Streptococcus gordonii, and H. pylori increased, whereas the coadherence of C. albicans with S. gordonii decreased. During the surgical video presentation the saliva-mediated adherence of H. pylori, S. sanguis, and Streptococcus mitis increased. These changes were independent of salivary flow rate, but correlated with specific changes in salivary protein composition. CONCLUSION: The results show that even moderate stressors, by altering the activity of the mucosal secretory glands, may affect microbial colonization processes such as adherence and coadherence. This study hereby presents a mechanism by which stress may affect the mucosal microflora and susceptibility to infectious disease.

Adult↗
PubMed1994

Theoretical and practical aspects of the quantification of biodiversity among microorganisms.

The quantification of biodiversity among microorganisms has to address both theoretical and practical aspects. Species concepts are often at variance with those applied in macroorganisms, and satisfactory concepts suitable for general use in bacteria and fungi have yet to be formulated. Molecular approaches have not yet provided a universal solution to this key issue. Quantification in habitats such as soil is difficult as isolation procedures yield only a small and skewed selection of the microorganisms present. Indices of taxonomic or phylogenetic diversity have potential in the quantification of microbial diversity at a range of ranks, but the non-equivalence of ranks and representatives of the taxa detected have to be addressed. Chemical and molecular methods have immense potential in the quantification of microbial diversity in environmental samples; 16S rRNA has shown particular promise with bacteria, but as yet the fungi lack a universal probe. A greater awareness of the limitations of existing approaches and methodologies used by microbiologists is needed, but significant progress can be anticipated as new technologies are developed and become more widely adopted.

Bacteria↗
PubMed1994

Metabolic activity of microorganisms in evaporites.

Crystalline salt is generally considered so hostile to most forms of life that it has been used for centuries as a preservative. Here, we present evidence that prokaryotes inhabiting a natural evaporite crust of halite and gypsum are metabolically active while inside the evaporite for at least 10 months. In situ measurements demonstrated that some of these "endoevaporitic" microorganisms (probably the cyanobacterium Synechococcus Nageli) fixed carbon and nitrogen. Denitrification was not observed. Our results quantified the slow microbial activity that can occur in salt crystals. Implications of this study include the possibility that microorganisms found in ancient evaporite deposits may have been part of an evaporite community.

Calcium Sulfate↗
PubMed2004

In vitro evaluation of the effectiveness of irrigants and intracanal medicaments on microorganisms within root canals.

AIM: To evaluate in vitro the effectiveness of sodium hypochlorite (NaOCl), chlorhexidine (CHX) and five intracanal medicaments on microorganisms within root canals. METHODOLOGY: Ninety-six human single-rooted extracted teeth were used. After removing the crowns, canal preparation was completed and the external root surfaces were coated with epoxy resin. Following sterilization, the teeth were contaminated with Candida albicans and Enterococcus faecalis, and were incubated at 37 +/- 1 degrees C for 7 days. The teeth were divided according to the irrigant solution or intracanal medicament: group 1, sterile physiologic solution (SPS) and calcium hydroxide (Ca(OH)2) paste; group 2, SPS and camphorated paramonochlorophenol (CPMC); group 3, SPS and tricresol formalin; group 4, SPS and CaOH2 + CPMC paste; group 5, SPS and PMC furacin; group 6, 2.5% NaOCl without intracanal medication; group 7, 2.0% CHX without intracanal medication and group 8, SPS without intracanal medication (control group). Microbiological samples were collected with sterile paper points, and bacterial growth was determined. The data were submitted to the analysis of variance (anova, P = 0.05). RESULTS: For C. albicans, groups 3 and 8 were statistically less effective than groups 1, 2, 4 and 5 (Kruskal-Wallis (K-W) = 65.241; gl = 7; P = 0.001). For E. faecalis, groups 6 and 8 were statistically less effective than groups 1-4 and 7 (K-W = 61.048; gl = 7; P = 0.001). CONCLUSIONS: Ca(OH)2 + CPMC paste was the most effective intracanal medicament for the elimination of the two microorganisms; 2.0% CHX solution was more effective than 2.5% NaOCl against E. faecalis.

Calcium Hydroxide↗
PubMed2006

The role of microorganisms in atopic dermatitis.

Atopic dermatitis (AD) is a common, fluctuating skin disease that is often associated with atopic conditions such as asthma and IgE-mediated food allergy and whose skin lesions are characterized by a Th-2 cell-mediated response to environmental antigens. The increasing prevalence and severity of atopic diseases including AD over the last three decades has been attributed to decreased exposure to microorganisms during early life, which may result in an altered Th-1/Th-2-balance and/or reduced T cell regulation of the immune response. Patients with AD exhibit defects in innate and acquired immune responses resulting in a heightened susceptibility to bacterial, fungal and viral infections, most notably colonization by S. aureus. Toxins produced by S. aureus exacerbate disease activity by both the induction of toxin-specific IgE and the activation of various cell types including Th-2 cells, eosinophils and keratinocytes. Allergens expressed by the yeast Malazessia furfur, a component of normal skin flora, have also been implicated in disease pathogenesis in a subset of AD patients. Microorganisms play an influential role in AD pathogenesis, interacting with disease susceptibility genes to cause initiation and/or exacerbation of disease activity.

Adaptor Proteins, Signal Transducing↗
PubMed1989

Characterization of selected gram-negative oral microorganisms by SDS-PAGE.

SDS-PAGE analysis of bacterial cell proteins was used to examine a diverse group of oral microorganisms. Most of the species examined, including physiologically similar microorganisms, produced distinct protein patterns which are characterized by the distribution of their major protein bands. The SDS-PAGE system described provides a rapid, simple and standardized identification technique to be used in consort with routine taxonomic procedures.

Bacterial Proteins↗
PubMed2004

Salivary IgA to cariogenic bacteria in HIV-positive children and its correlation with caries prevalence and levels of cariogenic microorganisms.

The interrelationship of HIV infection, dental caries and mucosal immune responses remains controversial. In our study population of 40 HIV-infected and 40 healthy control children (ages 2-5 years) there was a significantly higher prevalence of dental caries in HIV-infected children (P<0.05). The extent of caries correlated with the severity of HIV disease. To determine whether the immunosuppression that ensues after HIV infection could contribute to the increased caries prevalence, the concentrations of total IgA and IgA specific to cariogenic bacteria (Streptococcus mutans, Streptococcus sobrinus and Lactobacillus acidophilus) were determined in whole saliva by enzyme-linked immunosorbent assay. Levels of the same bacteria were also quantified in saliva using checkerboard DNA-DNA hybridization. A significantly increased level of total salivary IgA was found in the HIV-positive population (P < 0.05), but there were comparable titers of specific IgA to cariogenic bacteria in HIV-positive and healthy controls. The microbiological assessment also demonstrated similar levels of cariogenic microorganisms in both groups. We conclude that HIV-positive children appear to maintain the capacity to mount a mucosal immune response to cariogenic microorganisms, at least until late stages of disease.

Analysis of Variance↗
PubMed2005

Antimicrobial activity of Croton cajucara Benth linalool-rich essential oil on artificial biofilms and planktonic microorganisms.

We have previously demonstrated that a linalool-rich essential oil from Croton cajucara Benth presents leishmanicidal activity. In the present study, we demonstrate that this essential oil inhibits the growth of reference samples of Candida albicans, Lactobacillus casei, Staphylococcus aureus, Streptococcus sobrinus, Porphyromonas gingivalis and Streptococcus mutans cell suspensions, all of them associated with oral cavity disease. The purified linalool fraction was only inhibitory for C. albicans. Microbes of saliva specimens from human individuals with fixed orthodontic appliances, as well as the reference strains, were used to construct an artificial biofilm which was exposed to linalool or to the essential oil. As in microbial suspensions, the essential oil was toxic for all the microorganisms, while the purified linalool fraction mainly inhibited the growth of C. albicans. The compounds of the essential oil were separated by thin layer chromatography and exposed to the above-cited microorganisms. In this analysis, the proliferation of the bacterial cells was inhibited by still uncharacterized molecules, and linalool was confirmed as the antifungal component of the essential oil. The effects of linalool on the cell biology of C. albicans were evaluated by electron microscopy, which showed that linalool induced a reduction in cell size and abnormal germination. Neither the crude essential oil nor the purified linalool fraction is toxic to mammalian cells, which suggests that the essential oil or its purified components may be useful to control the microbial population in patients with fixed orthodontic appliances.

Acyclic Monoterpenes↗