PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “microbial detection”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 307 records · Page 17Linked to original sources
PubMed1994

Detection and differentiation of microbial siderophores by isoelectric focusing and chrome azurol S overlay.

Siderophores are microbial, low molecular weight iron-chelating compounds. Fluorescent Pseudomonads produce different, strain-specific fluorescent siderophores (pyoverdines) as well as non-fluorescent siderophores in response to low iron conditions. We present an isoelectric focusing method applicable to unpurified as well as to purified pyoverdine samples where the fluorescent siderophores are visualized under UV illumination. Siderophores from different Pseudomonas sp., amongst which are P. aeruginosa, P. fluorescens and P. putida, including egg yolk, rhizospheric and clinical isolates as well as some derived Tn5 mutants were separated by this technique. Different patterns could be observed for strains known to produce different siderophores. The application of the chrome azurol S assay as a gel overlay further allows immediate detection of non-fluorescent siderophores or possibly degradation products with residual siderophore activity. The method was also applied to other microbial siderophores such as deferrioxamine B.

Culture Media↗
PubMed1975

Use of electron microscopy for detection of viral and other microbial contaminants in bovine sera.

A total of 25 lots of bovine serum samples were pelleted in Beem capsules for thin sectioning and were examined by electron microscopy. These included 17 lots of fetal bovine serum pools and five lots of calf serum pools obtained from commercial sources, and three lots of adult bovine serum from local dairy farms. Virus-like particles, 50 to 300 nm in diameter, were detected in 17 of 25 (68%) of the sera. Five of 25 serum samples showed the presence of mycoplasma-like agents. Incubation of bovine serum at 35 C for 1 or 2 weeks appeared to destroy some of these agents, but in certain instances it enhanced bacteria and bacteriophage contaminants. The advantages of electron microscopy using the thin-sectioning technique for detection of microbial contamination in bovine sera are illustrated.

Animals↗
PubMed2005

The rapid evaluation of bacterial growth in blood cultures by selected ion flow tube-mass spectrometry (SIFT-MS) and comparison with the BacT/ALERT automated blood culture system.

We compared the performance of the BacT/ALERT automated blood culture system with real-time, quantitative volatile organic compound (VOC) detection by selected ion flow tube-mass spectrometry (SIFT-MS). Blood samples from healthy donors were artificially infected with 5 or 100 CFU of organisms commonly causing bacteremia. Positive results by SIFT-MS analysis of headspace gases were recorded for 53/60 (88.3%) bottles at 8h, and 58/60 (96.6%) bottles at 24 h. We conclude that SIFT-MS is a sensitive method for the detection of microbial VOCs. Furthermore, profiles of the VOCs detected may allow simultaneous identification of infecting organisms.

Automation↗
PubMed2004

Molecular biology and DNA microarray technology for microbial quality monitoring of water.

Public concern over polluted water is a major environmental issue worldwide. Microbial contamination of water arguably represents the most significant risk to human health on a global scale. An important challenge in modern water microbial quality monitoring is the rapid, specific, and sensitive detection of microbial indicators and waterborne pathogens. Presently, microbial tests are based essentially on time-consuming culture methods. Rapid microbiological analyses and detection of rare events in water systems are important challenges in water safety assessment since culture methods present serious limitations from both quantitative and qualitative points of view. To circumvent lengthy culture methods, newer enzymatic, immunological, and genetic methods are being developed as an alternative. DNA microarray technology is a new and promising tool that allows the detection of several hundred or even thousands DNA sequences simultaneously. Recent advances in sample processing and DNA microarray technologies provide new perspectives to assess microbial water quality. The aims of this review are to (1) summarize what is currently known about microbial indicators, (2) describe the most important waterborne pathogens, (3) present molecular methods used to monitor the presence of pathogens in water, and (4) show the potential of DNA microarrays in water quality monitoring.

Animals↗
PubMed1970

Sterility test method for petrolatum-based ophthalmic ointments.

A sensitive sterility testing procedure for the detection of microbial contamination in petrolatum-based ointments is described. The method involves dissolving the ointment in filter-sterilized isopropyl myristate and filtering through a membrane filter. Improved sensitivity is obtained by blending the membrane in Trypticase Soy Broth before incubation. Filter-sterilized isopropyl myristate is shown to be less toxic to microorganisms than heat-sterilized isopropyl myristate. The isopropyl myristate method is more sensitive than the polyethylene glycol-ether method for the detection of microbial contamination.

Bacillus subtilis↗
PubMed1996

Detection of inhibitors in milk by microbial tests. A review.

The demands concerning microbial inhibitor tests were subjected to marked changes during the last decades: It started with the claim of being able to detect contaminated milk which might cause problems during fermentation processes ('technological safety'). Due to the present day attention drawn to toxic and allergic hazards for numerous antimicrobials Maximum Residue Limits (MRLs) or safe/tolerance levels are fixed ('toxicological safety'). This means a variety of demands underlying permanent changes with respect to the 'detection pattern' which cannot be fulfilled by a single test. Within an Integrated Detection System microbial inhibitor tests play an important role as screening methods for those antimicrobials which can be detected with satisfactory sensitivities. This paper deals with some features of microbial inhibitor tests such as detection limits, performance susceptibility for interference factors, qualitative determination and standardization.

Animals↗
PubMed1991

Amniotic fluid white blood cell count: a rapid and simple test to diagnose microbial invasion of the amniotic cavity and predict preterm delivery.

The purpose of this study was to determine the value of amniotic fluid white blood cell count in the diagnosis of microbial invasion of the amniotic cavity. Amniotic fluid was retrieved by amniocentesis from 195 patients with preterm labor and intact membranes. Fluid was cultured for aerobic and anaerobic bacteria, as well as for mycoplasmas. The prevalence of a positive amniotic fluid culture was 12.8% (25/195). Patients with a positive amniotic fluid culture had a significantly higher median amniotic fluid white blood cell count than did patients with a negative amniotic fluid culture (median, 6 cells/mm3; range, 0 to 11,000 cells/mm3 vs median, 320 cells/mm3; range, 1 to 4480 cells/mm3; p less than 0.0001). An amniotic fluid white blood cell count greater than or equal to 50 cells/mm3 had a sensitivity of 80% (20/25), a specificity of 87.64% (149/170), a positive predictive value of 48.78% (20/41), and a negative predictive value of 96.75% (149/154) in the detection of a positive amniotic fluid culture for microorganisms. Although the sensitivity of an amniotic fluid white blood cell count (greater than or equal to 50 cells/mm3) in the detection of microbial invasion of the amniotic cavity was greater than that of the Gram stain of amniotic fluid (80% [20/25] vs 48% [12/25]; p less than 0.05), the specificity was lower (87.64% [149/170] vs 98.8% [168/170]; p less than 0.05). However, 88% (15/17) of all patients with an amniotic fluid white blood cell count greater than or equal to 50 cells/mm3 and a negative amniotic fluid culture had a spontaneous preterm delivery. We conclude that the amniotic fluid white blood cell count is a sensitive, simple, and inexpensive test for the detection of microbial invasion of the amniotic cavity. An elevated amniotic fluid white blood cell count is a risk factor for preterm delivery.

Adult↗
PubMed1993

A comparison of microbial bioassays for the detection of metal toxicity.

Heavy metal toxicity was studied by assaying six microbiological toxicity tests, both in solution and wastewater. Pseudomonas fluorescens and baker's yeast (Saccharomyces cerevisiae) were used; growth and respirometric determinations were performed. In addition, the Microtox test was employed as a reference method. The Microtox test is the most sensitive assay for detecting toxicity of zinc, copper, and mercury but not for cadmium, chromium, and nickel. Wastewater increases the sensitivity threshold (EC20) and EC50 values of the metals in most of the assays, which is correlated to the presence of organic and inorganic compounds that can reduce the bioavailability of the metals, leading to a general loss of sensitivity. All the above-mentioned assays are potentially useful in the detection of chemical toxicity of metals. However, each test shows different sensitivities to each metal, which is related to different sensitivities of the organisms used in the assays, as well as to other factors. Therefore, it would be advisable to use a battery of tests for biological evaluation of metal toxicity.

Lethal Dose 50↗
PubMed2001

Combination of competitive quantitative PCR and constant-denaturant capillary electrophoresis for high-resolution detection and enumeration of microbial cells.

A novel quantitative PCR (QPCR) approach, which combines competitive PCR with constant-denaturant capillary electrophoresis (CDCE), was adapted for enumerating microbial cells in environmental samples using the marine nanoflagellate Cafeteria roenbergensis as a model organism. Competitive PCR has been used successfully for quantification of DNA in environmental samples. However, this technique is labor intensive, and its accuracy is dependent on an internal competitor, which must possess the same amplification efficiency as the target yet can be easily discriminated from the target DNA. The use of CDCE circumvented these problems, as its high resolution permitted the use of an internal competitor which differed from the target DNA fragment by a single base and thus ensured that both sequences could be amplified with equal efficiency. The sensitivity of CDCE also enabled specific and precise detection of sequences over a broad range of concentrations. The combined competitive QPCR and CDCE approach accurately enumerated C. roenbergensis cells in eutrophic, coastal seawater at abundances ranging from approximately 10 to 10(4) cells x ml(-1). The QPCR cell estimates were confirmed by fluorescent in situ hybridization counts, but estimates of samples with <50 cells x ml(-1) by QPCR were less variable. This novel approach extends the usefulness of competitive QPCR by demonstrating its ability to reliably enumerate microorganisms at a range of environmentally relevant cell concentrations in complex aquatic samples.

Animals↗
PubMed2006

The rapid evaluation of bacterial growth and antibiotic susceptibility in blood cultures by selected ion flow tube mass spectrometry.

We have measured the production of volatile organic compounds (VOCs) by selected ion flow tube mass spectrometry (SIFT-MS) in the headspaces of conventional BacT/ALERT blood culture bottles (Biomerieux, Durham, NC) artificially infected with 5 bacterial strains. Uninfected blood samples were inoculated with Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus pneumoniae, Escherichia coli, and Neisseria meningitidis. Growth and species identification were determined at 6 h by measuring a panel of 9 VOC products. Two species, E. coli and S. aureus, were also incubated in the presence of gentamicin or flucloxacillin, respectively, above or below their demonstrated MIC. The concentration-dependent antibiotic susceptibility of both strains was demonstrated by the inhibition of VOC production at 22 h (P < .05). These results suggest incorporating SIFT-MS detection of microbial VOCs as a sensitive method for bacterial detection, identification, and determination of antibiotic susceptibility in a conventional blood culture system.

Bacteremia↗
PubMed2006

[Clinical study on bacterial translocation in severe multiple trauma patients].

OBJECTIVE: To investigate bacterial translocation in severe multiple trauma patients using polymerase chain reaction (PCR) to detect the presence of bacteria in the blood. METHODS: Sixteen severe multiple trauma patients [injury severity score (ISS)>20] in surgery intensive care unit (SICU) were selected. Blood samples were collected 2, 24 and 48 hours after trauma for bacterial culture and microbial DNA detection. Meanwhile, plasma levels of D-lactate and lipopolysaccharide (LPS) in systemic circulation were determined. PCR was performed after DNA extraction, with target beta-lactosidase gene of E. coli and 16SrRNA gene of most pathogenic bacteria. All patients were observed within 30 days for infectious complications. D-lactate and LPS levels were determined in 63 patients before selective operation. RESULTS: Microbial DNA could be detected in blood as early as 2 hours following severe trauma, and altogether positive results were found in 10 patients (62.50%). All PCR-positive patients manifested sepsis, but none of the PCR-negative patients did (P<0.01). Bacterial DNA was discovered in 100.00% of sepsis patients and none in non-sepsis patients (P<0.01). Seventy percent of PCR-positive patients developed infectious complications, while none of PCR-negative patients did (P<0.01). The blood culture was positive only in 3 patients (18.75%), all of them were PCR-positive. E.coli DNA was found in 70.00% of all the PCR positive blood specimens. Systemic plasma concentration of D-lactate and LPS of all patients was significantly higher than that in control group, which consisted of 63 inpatients waiting for elective operations. Systemic plasma level of D-lactate showed a positive correlation with that of LPS (r=0.94, P<0.01). CONCLUSION: Intestinal bacterial translocation (most commonly E. coli) might occur early (2 hours) after severe trauma. Infection and sepsis have a close relationship with bacterial translocation. Detection of blood microbial DNA using PCR could reflect bacteria translocation and forecast imminent infection and sepsis.

Adolescent↗
PubMed1996

FET-microbial sensor for xylose detection based on Gluconobacter oxydans cells.

A potentiometric biosensor for xylose was devised utilizing Gluconobacter oxydans whole cells. Immobilization methods based on physical adsorption were used for G. oxydans cells and extracellular pH changes resulting from xylose dehydrogenation were monitored by a field effect transistor (FET). The G. oxydans, FET-based sensor detected xylose at a lower limit of 0.5 mM. From 5.0 to 30 mM xylose, the response of the sensor was linear. Expectedly, output signals were significantly suppressed by buffer (Tris-HCl). Responses were essentially stable for at least four weeks of storage and showed only a slight loss of initial xylose sensitivity. Xylitol exerted an insignificant influence on the sensor's response to xylose. However, the response to glucose was 5 times higher in relation to that of xylose at the same concentration (1 mM). For xylose determinations in the presence of glucose, a two-step assay is discussed.

Acetobacteraceae↗
PubMed2005

Application of 16S rDNA-PCR amplification and DGGE fingerprinting for detection of shift in microbial community diversity in Cu-, Zn-, and Cd-contaminated paddy soils.

Seven soils were sampled from farmland at different distances (0.01-5 km) from a copper and zinc smelter. The total contents of heavy metals in these soils ranged from 46 to 4895 mg Cu kg-1, 96 to 1133 mg Zn kg-1, and 6.9 to 28.8 mg Cd kg-1, respectively. The available fractions were highly correlated with total contents of the metals. In order to assess the impact of combined contamination of heavy metals on soil bacterial communities, denaturing gradient gel electrophoresis (DGGE) of polymerase chain reaction (PCR) amplicons of 16S rDNA sequence of bacteria in soil was used. Bacterial community structure was affected to some extent by heavy metals. The number of DGGE bands in soils increased with increasing distance from the copper and zinc smelter. Clustering analysis of the DGGE profiles showed that bacteria in the seven soils belonged to three clusters. Bacterial communities in three soils sampled at 0.01-0.60 km from the smelter belonged to one cluster, and those in three soils sampled at 0.8-1.2 km from the smelter belong to another cluster. Bacterial community in soil farthest from the smelter belonged to a single cluster. This study demonstrated that heavy metal contamination decreased both biomass and diversity of bacterial community in the soil.

Cadmium↗
PubMed2001

Toll-like receptors and innate immunity.

Toll-like receptors have a crucial role in the detection of microbial infection in mammals and insects. In mammals, these receptors have evolved to recognize conserved products unique to microbial metabolism. This specificity allows the Toll proteins to detect the presence of infection and to induce activation of inflammatory and antimicrobial innate immune responses. Recognition of microbial products by Toll-like receptors expressed on dendritic cells triggers functional maturation of dendritic cells and leads to initiation of antigen-specific adaptive immune responses.

Adaptation, Physiological↗
PubMed2002

Microbial quality of wastewater: detection of hepatitis A virus by reverse transcriptase-polymerase chain reaction.

AIMS: The persistent circulation of hepatitis A virus (HAV) in the Mediterranean area suggests the need for monitoring its presence in the environment. A reverse transcriptase-polymerase chain reaction (RT-PCR) was used to detect the presence of HAV in several consecutive raw sewage and final effluent samples, collected over an 8-month period from an activated sludge treatment plant in southern Italy. METHODS AND RESULTS: Two distinct purification protocols, either based on antigen-capture with monoclonal antibody (AC) or RNA extraction, were compared. The possible influence of the antibody used in the AC phase was evaluated in preliminary experiments on HAV-spiked samples, using two different monoclonal antibodies. Hepatitis A virus RNA was detected in all but one sewage environmental sample examined. The contemporary presence of enteroviruses, reoviruses and phages was observed, while HAV growth in cell culture was hampered. CONCLUSIONS: The RT-PCR technique was confirmed to be a valuable tool for the rapid monitoring of HAV in sewage samples. In addition, this study demonstrated that application of different sample purification methods can result in different levels of sensitivity of the assay and that, in the antigen-capture method, the choice of antibody can have a crucial role. SIGNIFICANCE AND IMPACT OF THE STUDY: This work underlines the need for technical uniformity in environmental studies from different laboratories for a correct and useful comparison of the results.

Amino Acid Sequence↗
PubMed2006

Impact of microbial diversity on rapid detection of enterohemorrhagic Escherichia coli in surface waters.

Enterohemorrhagic Escherichia coli (EHEC) are a physiologically, immunologically and genetically diverse collection of strains that pose a serious water-borne threat to human health. Consequently, immunological and PCR assays have been developed for the rapid, sensitive detection of presumptive EHEC. However, the ability of these assays to consistently detect presumptive EHEC while excluding closely related non-EHEC strains has not been documented. We conducted a 30-month monitoring study of a major metropolitan watershed. Surface water samples were analyzed using an immunological assay for E. coli O157 (the predominant strain worldwide) and a multiplex PCR assay for the virulence genes stx(1), stx(2) and eae. The mean frequency of water samples positive for the presence of E. coli O157, stx(1) or stx(2) genes, or the eae gene was 50%, 26% and 96%, respectively. Quantitative analysis of selected enriched water samples indicated that even in samples positive for E. coli O157 cells, stx(1)/stx(2) genes, and the eae gene, the concentrations were rarely comparable. Seventeen E. coli O157 strains were isolated, however, none were EHEC. These data indicate the presence of multiple strains similar to EHEC but less pathogenic. These findings have important ramifications for the rapid detection of presumptive EHEC; namely, that current immunological or PCR assays cannot reliably identify water-borne EHEC strains.

Adhesins, Bacterial↗