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At least 487 records · Page 27Linked to original sources
PubMed1973

Survival of microorganisms in laundered polyester-cotton sheeting.

The effects of wash-water temperature, cold-water or regular detergent, wash-cycle design, drying, and drying temperature on survival of four microorganisms on polyester-cotton sheeting were examined. Escherichia coli T3 bacteriophage survived washing at 24, 35, 46, and 57 C, but not at 68 C. Serratia marcescens survived only the lowest three wash temperatures. Levels of residual Staphylococcus aureus were diminished at the highest two wash temperatures, but survival was substantial even at 68 C. Counts of Bacillus stearothermophilus spores were not altered appreciably by wash temperature. Type of detergent had no practical effect on observed counts. The regular wash cycle was significantly more efficient in removal of microorganisms than the permanent-press cycle. Counts, especially of the bacteriophage and the gramnegative bacterium, were decreased by drying; after drying, the effects of wash-water temperature on S. aureus and B. stearothermophilus were not significantly different. Microorganisms were transferred from inoculated to sterilized sheeting during laundering. The public health significance of these observations is discussed.

Bacillus↗
PubMed2002

Biofilms: survival mechanisms of clinically relevant microorganisms.

Though biofilms were first described by Antonie van Leeuwenhoek, the theory describing the biofilm process was not developed until 1978. We now understand that biofilms are universal, occurring in aquatic and industrial water systems as well as a large number of environments and medical devices relevant for public health. Using tools such as the scanning electron microscope and, more recently, the confocal laser scanning microscope, biofilm researchers now understand that biofilms are not unstructured, homogeneous deposits of cells and accumulated slime, but complex communities of surface-associated cells enclosed in a polymer matrix containing open water channels. Further studies have shown that the biofilm phenotype can be described in terms of the genes expressed by biofilm-associated cells. Microorganisms growing in a biofilm are highly resistant to antimicrobial agents by one or more mechanisms. Biofilm-associated microorganisms have been shown to be associated with several human diseases, such as native valve endocarditis and cystic fibrosis, and to colonize a wide variety of medical devices. Though epidemiologic evidence points to biofilms as a source of several infectious diseases, the exact mechanisms by which biofilm-associated microorganisms elicit disease are poorly understood. Detachment of cells or cell aggregates, production of endotoxin, increased resistance to the host immune system, and provision of a niche for the generation of resistant organisms are all biofilm processes which could initiate the disease process. Effective strategies to prevent or control biofilms on medical devices must take into consideration the unique and tenacious nature of biofilms. Current intervention strategies are designed to prevent initial device colonization, minimize microbial cell attachment to the device, penetrate the biofilm matrix and kill the associated cells, or remove the device from the patient. In the future, treatments may be based on inhibition of genes involved in cell attachment and biofilm formation.

Bacteria↗
PubMed1978

Immunological relatedness of ribosomes from mycobacteria, nocardiae and corynebacteria, and microorganisms in leprosy lesions.

Serological relatedness of ribosomes from microorganisms of the Mycobacterium, Nocardia, and Corynebacterium genera has been analyzed by the microplate immunodiffusion technique. Mycobacterium and Nocardia proved homogeneous and closely related taxa, whereas Corynebacterium was found to be a heterogeneous phylum connected by remote links to the others. The taxonomic position of "diphtheroid microorganisms" (non-acid-fast, gram-positive bacteria morphologically similar to corynebactria), which were found together with Mycobacterium leprae in human leprosy lesions, was also investigated. Ribosomes of diphtheroid bacteria strongly cross-reacted with antisera against several mycobacteria and nocardiae but not against corynebacteria. Moreover, ribosomes from independently isolated diphtheroid strains proved serologically related and yielded strong cross-reactions with antisera against M. leprae as well as with sera from leprosy patients. Hence, diphtheroid microorganisms represent a homogeneous group immunologically related to mycobacteria in general and more specifically to M. leprae.

Corynebacterium↗
PubMed1980

Selective antibacterial properties of lysozyme for oral microorganisms.

The antibacterial properties of lysozyme were investigated with oral microorganisms representing the seven serotypes (a through g) of Streptococcus mutans, Veillonella alcalescens, and the virulent (V) and avirulent (AV) strains of Actinomyces viscosus T14. Growth of bacteria in defined medium was monitored spectrophotometrically after the addition of various amounts (25 mug to 5 mg/ml) of enzyme. No growth inhibition of V. alcalescens was observed. Inhibition of A. viscosus T14(V) and A. viscosus T14(AV) occurred with 160 mug of lysozyme per ml. Of the S. mutans cultures tested, the serotype a and b strains were inhibited with as little as 25 mug of enzyme per ml, whereas e and f strains were most resistant to the bacteriostatic activity of lysozyme. The presence of dl-threonine or sucrose in growth medium did not significantly affect the results. A lysoplate assay was developed to rapidly survey the bacterial cultures for their susceptibility to the lytic ability of the enzyme. Lysis, as a measure of a zone of clearing in agarose plates, occurred for all microorganisms in the presence of lysozyme after the subsequent addition of NaCl or detergent. The bactericidal activity of lysozyme was determined on S. mutans BHT and S. mutans LM-7 by the pour plate technique. Preincubation of S. mutans LM-7 with as much as 1 mg of enzyme for 90 min did not affect viability or growth, whereas preincubation of S. mutans BHT with 1 mg of lysozyme resulted in no recoverable colony-forming units. An antigen containing extract of S. mutans LM-7 blocked the growth inhibitory property of lysozyme. Human lysozyme was a more effective antibacterial factor than hen egg white lysozyme. Total growth inhibition of S. mutans BHT was effected with 40 mug of human enzyme, and as little as 10 mug of human enzyme inhibited growth for greater than 20 h. The data presented indicate that different mechanisms may be responsible for the bacteriostatic, lytic, and bactericidal properties of the enzyme and that lysozyme is a selective but effective antibacterial factor for oral microorganisms.

Actinomyces↗
PubMed1985

Effect of subgingival scaling on systemic antibody responses to oral microorganisms.

The effects of scaling and root planing treatment on systemic antibody responses were studied in patients with periodontal disease and in normal subjects. Immunoglobulin G antibody in serum to a battery of oral microorganisms was assessed in an enzyme-linked immunosorbent assay before and after treatment in 31 individuals. The majority (96%) of the diseased patients exhibited elevated antibody to one or more of the microorganisms before the scaling regime. Significant increases in antibody levels in serum were noted in 16 of 19 patients after scaling, whereas only 2 of 12 nonscaled subjects showed similar changes during monitoring intervals of up to 3 years. The bacterial specificities of the increases were found to differ among the patients; however, a significant correlation to preexisting elevated antibody levels was observed. Peak levels of responses were noted at approximately 2 to 4 months posttreatment; antibody returned to pretreatment levels by 8 to 12 months. The predominant organisms for which changes were noted included the black-pigmented Bacteroides spp., Eikenella corrodens, Campylobacter concisus, and Actinobacillus actinomycetemcomitans. In 18 of 19 instances, the homologous microorganism was detected in the subgingival plaque when elevated antibody was present after treatment. These findings indicated that specific changes in host systemic responses accompany scaling and root planing treatment of periodontal disease patients. These alterations in the host response may provide an additional means by which successful therapy can be accomplished.

Actinobacillus↗
PubMed1987

Metabolism of glycosylsucrose by oral microorganisms and its hydrolysis by Streptococcus salivarius fructosyltransferase.

Resting-cell suspensions of oral microorganisms grown in sucrose were studied for the production of acid from glucosylsucrose and maltosylsucrose. Most oral microorganisms fermented these sugars to only a limited extent. Streptococcus salivarius, however, metabolized glucosylsucrose as well as sucrose. We therefore looked for a specific enzyme in S. salivarius which was capable of hydrolyzing glucosylsucrose. Fructosyltransferase and invertase were purified from S. salivarius 13419, and the substrate specificities and hydrolytic activities of these enzymes were determined. Purified fructosyltransferase catalyzed fructan synthesis from glucosylsucrose or maltosylsucrose, whereas purified invertase barely hydrolyzed these sugars. These results suggest that the high fermentative efficiency of glycosylsucrose by S. salivarius is due to the hydrolysis of these sugars by fructosyltransferase, but not by invertase. The partially purified fructosyltransferases of Actinomyces viscosus NY1 and Streptococcus mutans NCIB 11723 catalyzed fructan synthesis from glucosylsucrose or maltosylsucrose. The fructosyltransferases of these oral microorganisms are also responsible for the hydrolysis of glycosylsucrose.

Actinomyces↗
PubMed1982

Occurrence of alpha-tocopherolquinone and alpha-tocopherolquinol in microorganisms.

Both alpha-tocopherolquinol and alpha-tocopherolquinone were found in 56 of 93 strains of microorganisms examined. Organisms that contained these compounds included the single example of a eucaryotic alga, a Euglena, and a cyanobacterium (blue-green alga), 22 of 32 genera of bacteria, and 9 genera of yeasts. In the bacteria and yeasts the levels of quinone and hydroquinone were nearly equal and averaged about 3 nmol of each compound g-1 of packed cells. Included among the bacteria that contained these compounds were three examples from the newly proposed kingdom of Archaebacteriae. Those microorganisms that did not contain alpha-tocopherolquinol or alpha-tocopherolquinone tended to fall into two groups. One group consisted of gram-positive, anaerobic or facultative bacteria with a low content of guanine and cytosine, and the second group encompassed all of the filamentous microorganisms studied. No metabolic function is known for alpha-tocopherolquinol or its quinone other than as a cofactor in the biohydrogenation of unsaturated fatty acids that can be carried out by only a few organisms.

Bacteria↗
PubMed1997

A study of iterative type II polyketide synthases, using bacterial genes cloned from soil DNA: a means to access and use genes from uncultured microorganisms.

To examine as randomly as possible the role of the beta-ketoacyl and acyl carrier protein (ACP) components of bacterial type II polyketide synthases (PKSs), homologs of the chain-length-factor (CLF) genes were cloned from the environmental community of microorganisms. With PCR primers derived from conserved regions of known ketosynthase (KSalpha) and ACP genes specifying the formation of 16- to 24-carbon polyketides, two CLF (KSbeta) genes were cloned from unclassified streptomycetes isolated from the soil, and two were cloned from soil DNA without the prior isolation of the parent microorganism. The sequence and deduced product of each gene were distinct from those of known KSbeta genes and, by phylogenetic analysis, belonged to antibiotic-producing PKS gene clusters. Hybrid PKS gene cassettes were constructed with each novel KSbeta gene substituted for the actI-ORF2 or tcmL KSbeta subunit genes, along with the respective actI-ORF1 or tcmK KSalpha, tcmM ACP, and tcmN cyclase genes, and were found to produce an octaketide or decaketide product characteristic of the ones known to be made by the heterologous KSalpha gene partner. Since substantially less than 1% of the microorganisms present in soil are thought to be cultivatable by standard methods, this work demonstrates a potential way to gain access to a more extensive range of microbial molecular diversity and to biosynthetic pathways whose products can be tested for biological applications.

Acyl Carrier Protein↗
PubMed1962

BACTERIAL OXIDATION OF DIPICOLINIC ACID I. : Isolation of Microorganisms, Their Culture Conditions, and End Products.

Arima, Kei (University of Tokyo, Tokyo, Japan) and Yasuo Kobayashi. Bacterial oxidation of dipicolinic acid. I. Isolation of microorganisms, their culture conditions, and end products. J. Bacteriol. 84:759-764. 1962.-In a study of the metabolic pathway(s) of dipicolinic acid (DPA) in microorganisms, 436 strains of soil microorganisms were isolated by use of an enrichment culture technique. Most of them were bacteria, and one of them, Achromobacter, which had the strongest DPA-oxidizing activity, was used for the following experiments. In DPA-free medium, the enzymes which oxidize DPA were not produced. The best culture condition for enzyme production and cell growth was: Nutrient Broth supplemented with 0.1% DPA, 30 C, and 20 hr of shake culture. End products were oxalic acid, NH(3), and CO(2). Oxalic acid was not oxidized further by this bacterium. The over-all reaction equation of DPA oxidation was determined.

Journal Article↗
PubMed1966

Bacteriostatic action of progesterone on staphylococci and other microorganisms.

Yotis, William (Loyola University, Hines, Ill.), and Ronald Stanke. Bacteriostatic action of progesterone on staphylococci and other microorganisms. J. Bacteriol. 92:1285-1289. 1966.-Progesterone has been examined in vitro for antibacterial activity against 10 microorganisms. Turbidimetric and manometric techniques were used to assay the antibacterial activity of progesterone. The organisms tested consisted of Staphylococcus aureus, S. epidermidis, Gaffkya tetragena, Bacillus subtilis, Listeria monocytogenes, Candida albicans, Escherichia coli, Aerobacter aerogenes, Salmonella paratyphi, and Proteus vulgaris. Antibacterial action was shown by progesterone only against the gram-positive microorganisms when they were grown in tryptic soy broth containing 10 to 20 mug of progesterone per ml. Pregnenolone, 4-pregnen-20beta-ol-3-one, and 5alpha-pregnane also possessed antistaphylococcal properties, whereas pregnanolone, pregnandione, 11alpha-hydroxyprogesterone, and 17alpha-hydroxyprogesterone did not. The bacteriostatic action of progesterone on staphylococci was exerted primarily during the first 8 hr of incubation, and it was reduced in the presence of oxygen. In the presence of 20 mug of progesterone per ml, there was significant reduction in the oxidation by resting staphylococcal suspensions or utilization by staphylococci of pyruvate as an energy source during growth.

Anti-Bacterial Agents↗
PubMed1983

Fibrinogenolytic and fibrinolytic activity in oral microorganisms.

Samples were taken from blood accumulated in dental alveoli after surgical removal of mandibular third molars, from subgingival plaque of teeth with advanced periodontal destructions, from teeth with infected necrotic pulps, and from subjects suffering from angular cheilitis. Of the microorganisms subcultured from these samples, 116 strains were assayed for enzymes degrading fibrinogen and fibrin. Enzymes degrading fibrinogen were assayed with the thin-layer enzyme assay cultivation technique. This assay involves the cultivation of microorganisms on culture agars applied over fibrinogen-coated polystyrene surfaces. Enzymes degrading fibrin were assayed with both a plate assay and a tube assay, in which fibrin was mixed with a microbial culture medium. Microorganisms degrading fibrinogen or fibrin or both were isolated from all sampling sites. Activity was mainly detected in strains of Actinomyces, Bacteroides, Fusobacterium, Peptococcus, Propionibacterium, and Staphylococcus aureus. Most Fusobacterium strains degraded fibrinogen only. Enzymes degrading fibrinogen as well as enzymes degrading fibrin via activation of plasminogen were revealed in strains of Clostridium, S. aureus, and Streptococcus pyogenes. It was generally found that fibrinogen was degraded by more strains than was fibrin, which indicates that different proteases may be involved.

Bacteria↗
PubMed1984

Rapid visual detection of microorganisms in blood culture.

We describe a method and apparatus for rapid visual detection of microorganisms in blood cultures. In the 30-min procedure, a lysing reagent for the preferential digestion of blood cells and a concentration device which causes 1 ml of lysed specimen to pass through a portion (3 mm2) of a membrane filter (pore size, 0.6 micron) were used. After the material remaining on the filter was Gram stained, the filter was mounted and examined microscopically. The ability to detect microorganisms in blood cultures was determined by spiking seven common blood pathogens into blood cultures prepared from the blood of healthy volunteers. Microorganism concentration in the cultures ranged from 1 to 1,000/ml. All of 34 cultures with at least 100 CFU/ml were detected, 34 of 64 cultures with less than 100 CFU/ml were detected, and 41 of 42 negative controls were correctly reported as negative.

Bacteriological Techniques↗
PubMed1985

Immobilization of microorganisms for detection by solid-phase immunoassays.

Several cultures of gram-negative and gram-positive bacteria were successfully immobilized with titanous hydroxide. The immobilization efficiency for the microorganisms investigated in saline and broth media ranged from 80.2 to 99.9%. The immobilization of salmonellae was effective over a wide pH range. The presence of buffers, particularly phosphate buffer, drastically reduced the immobilization rate. However, buffers may be added to immunoassay systems after immobilization of microorganisms. The immobilization process involved only one step, i.e., shaking 100 microliter of culture with 50 microliter of titanous hydroxide suspension in polystyrene tubes for only 10 min. The immobilized cells were so tenaciously bound that vigorous agitation for 24 h did not result in cell dissociation. The nonspecific binding of 125I-labeled antibody from rabbits and 125I-labeled protein A by titanous hydroxide was inhibited in the presence of 2% gelatin and amounted to only 5.6 and 3.9%, respectively. We conclude that this immobilization procedure is a potentially powerful tool which could be utilized in solid-phase immunoassays concerned with the diagnosis of microorganisms.

Bacteriological Techniques↗
PubMed1985

Agar media that indicate acid production from sorbitol by oral microorganisms.

Two varieties of agar medium (Trypticase [BBL Microbiology Systems]-serum-sorbitol-bromcresol purple agar [TSSB] and Trypticase-blood-sorbitol-CaCO3 agar [TBSCa]) indicating microbial acid production from sorbitol were tested. The media were devised for use in studies on the prevalence of sorbitol-fermenting human oral microorganisms incubated in an anaerobic or microaerophilic atmosphere containing 5 to 6% CO2. TSSB contains bromcresol purple as the pH indicator and NaHCO3 as the main buffering salt. TBSCa contains CaCO3 as both the buffering salt and the indicator of acid production. The growth yield of pure cultures of oral microorganisms on TBSCa was shown to equal that on blood agar incubated under similar conditions. TSSB inhibited the growth of several bacteria to various extents. The recovery of sorbitol-fermenting microorganisms from oral specimens was the greatest when the specimens were assayed with TBSCa. The poorer results obtained with TSSB were mainly due to the decoloration of the pH indicator in this medium and the presence of greater numbers of sorbitol false-positive colonies.

Acids↗
PubMed1991

Detection of variable DNA repeats in diverse eukaryotic microorganisms by a single set of polymerase chain reaction primers.

We cloned and sequenced a variable DNA repeat from Trichomonas vaginalis, a flagellated protozoan parasite. Targeting of this repeat in the polymerase chain reaction resulted in complex and intense product patterns for a wide variety of eukaryotic microorganisms, including the pathogenic protozoan parasites T. vaginalis, Giardia lamblia, Leishmania donovani, three species of Trypanosoma, and four species of Acanthamoeba; the nonpathogenic protozoans, Paramecium tetraurelia and Tetrahymena thermophilia; and a yeast, Saccharomyces cerevisiae. Each microorganism exhibited a distinctive pattern of repeats. For example, a characteristic pattern was exhibited by six clinical T. vaginalis isolates. Eight G. lamblia isolates exhibited either one of two characteristic pattern types. There was no reaction with human DNA or DNA from the prokaryotes Ureaplasma urealyticum and Mycoplasma hominis. This approach may facilitate detection of a wide variety of eukaryotic microorganisms by use of a single primer set and holds promise for the development of typing schemes for both T. vaginalis and G. lamblia.

Acanthamoeba↗
PubMed1997

Fate and activity of microorganisms introduced into soil.

Introduced microorganisms are potentially powerful agents for manipulation of processes and/or components in soil. Fields of application include enhancement of crop growth, protection of crops against plant-pathogenic organisms, stimulation of biodegradation of xenobiotic compounds (bioaugmentation), and improvement of soil structure. Inoculation of soils has already been applied for decades, but it has often yielded inconsistent or disappointing results. This is caused mainly by a commonly observed rapid decline in inoculant population activity following introduction into soil, i.e., a decline of the numbers of inoculant cells and/or a decline of the (average) activity per cell. In this review, we discuss the available information on the effects of key factors that determine the fate and activity of microorganisms introduced into soil, with emphasis on bacteria. The factors addressed include the physiological status of the inoculant cells, the biotic and abiotic interactions in soil, soil properties, and substrate availability. Finally, we address the possibilities available to effectively manipulate the fate and activity of introduced microorganisms in relation to the main areas of their application.

Bacterial Physiological Phenomena↗
PubMed2006

Adaptation and acclimation of photosynthetic microorganisms to permanently cold environments.

Persistently cold environments constitute one of our world's largest ecosystems, and microorganisms dominate the biomass and metabolic activity in these extreme environments. The stress of low temperatures on life is exacerbated in organisms that rely on photoautrophic production of organic carbon and energy sources. Phototrophic organisms must coordinate temperature-independent reactions of light absorption and photochemistry with temperature-dependent processes of electron transport and utilization of energy sources through growth and metabolism. Despite this conundrum, phototrophic microorganisms thrive in all cold ecosystems described and (together with chemoautrophs) provide the base of autotrophic production in low-temperature food webs. Psychrophilic (organisms with a requirement for low growth temperatures) and psychrotolerant (organisms tolerant of low growth temperatures) photoautotrophs rely on low-temperature acclimative and adaptive strategies that have been described for other low-temperature-adapted heterotrophic organisms, such as cold-active proteins and maintenance of membrane fluidity. In addition, photoautrophic organisms possess other strategies to balance the absorption of light and the transduction of light energy to stored chemical energy products (NADPH and ATP) with downstream consumption of photosynthetically derived energy products at low temperatures. Lastly, differential adaptive and acclimative mechanisms exist in phototrophic microorganisms residing in low-temperature environments that are exposed to constant low-light environments versus high-light- and high-UV-exposed phototrophic assemblages.

Acclimatization↗
PubMed1998

Clinical and morphological characteristics in Streptococcus bovis endocarditis: a comparison with other causative microorganisms in 177 cases.

AIM: To compare the clinical and morphological characteristics of patients with Streptococcus bovis endocarditis with those of patients with endocarditis caused by other microorganisms. METHODS: 177 consecutive patients (Streptococcus bovis, 22; other streptococci, 94; staphylococci, 44; other, 17) with definite infective endocarditis according to the Duke criteria were included. All patients underwent transthoracic and transoesophageal echocardiography. In 88 patients, findings from surgery/necropsy were obtained. RESULTS: S bovis endocarditis was associated with older patients, with a higher mortality (p = 0.04), and with a higher rate of cardiac surgery (p < 0.001) than other microorganisms, although embolic events were observed less often (p = 0.02). Pathological gastrointestinal lesions were detected in 45% of the patients. Multiple valves were affected in 68% of the patients with S bovis endocarditis and in 20% of those with other organisms (p < 0.001). Moderate or severe regurgitation occurred more often in S bovis endocarditis than with other microorganisms (p = 0.05). When surgery or necropsy was performed, infectious myocardial infiltration of the left ventricle was confirmed histopathologically in 36% of the patients with S bovis endocarditis and in 10% of those with other organisms (p = 0.002). CONCLUSIONS: S bovis endocarditis is a severe illness because of the more common involvement of multiple valves, and of the frequent occurrence of haemodynamically relevant valvar regurgitation and infectious myocardial infiltration.

Adult↗