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Microbiological Methods (microbiological + methods)
Selected AbstractsCalorimetric investigations into the starvation response of Pseudomonas putida growing on phenol and glucoseJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2009Andreas Lißner Abstract Aims:, To investigate the stress response during nutrient deprivation, particularly with regard to the application of phenol as growth substrate of Pseudomonas putida with calorimetric measurements as a new method. Methods and Results:, The online and noninvasive measurement of the thermal power P0 permits the detection of microbial activity during the starvation period. While the results of the investigations with phenol reveal a significant loss of activity as a function of the temporal nutrient dosage, only a small loss of activity was detected by using glucose. Microbiological methods (colony forming units (CFU) and activity of catechol-2,3-dioxygenase) showed a loss of the enzyme activity at a constant CFU. The introduction of a simple decay parameter kD in the kinetic description of the growth process on phenol was sufficient for the successful kinetic modelling. Conclusions:, The combination of calorimetric measurements and the determination of the enzymatic activity proved the loss of activity of Ps. putida during the deprivation of the substrate phenol. Significance and Impact of the study:, The initial heat power (P0) proves to be a suitable parameter for the characterization of the physiological state of the culture and can be used for the regulation of nutrient supply in biotechnological process development. [source] Implementation of quality control methods (physico-chemical, microbiological and sensory) in conjunction with multivariate analysis towards fish authenticityINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 3 2005Ioannis S. Arvanitoyannis Summary Nowadays authenticity of foods and fish in particular has become of crucial importance because of high number of adulteration cases. Authenticity control has gained ground thanks to the development of several rapid physico-chemical and microbiological methods aiming at distinguishing one species from another based on solid scientific evidence. It has been proven that despite the precision and accuracy of robust analytical and protein and DNA-based techniques, detection of authenticity could not be claimed without resorting to multivariate analysis. This review summarizes both the most advanced and state of the art used techniques for detecting fish and seafood authenticity (both in terms of species and geographical origin). Another issue reported in this review is the preservation of fish and seafood through the implementation of old and novel techniques (ice, modified atmosphere packaging). Several informative tables were included in this paper referring to the employed quality control and sensory analysis methods and multivariate analysis for fish and seafood. [source] Prevalence of enterohaemorrhagic Escherichia coli from serotype O157 and other attaching and effacing Escherichia coli on bovine carcasses in AlgeriaJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2006A. Chahed Abstract Aims:, Bovine meat is the principal source of human contamination of attaching and effacing Escherichia coli, including enterohaemorrhagic E. coli O157. The aim was to study the prevalence of these strains on bovine carcasses in Algeria. Methods and Results:, Two-hundred and thirty carcasses were swabbed and analysed by classical microbiological methods for total E. coli counts and for the presence of pathogenic E. coli. The E. coli counts were high, with a 75th percentile of 444·75 CFUs cm,2. For pathogenic E. coli, more than 7% of the tested carcasses were positive for E. coli O157. Eighteen E. coli O157 strains were isolated and typed by multiplex PCR. The main isolated pathotype (78%) was eae+ stx2+ ehxA+. In addition to E. coli O157, other attaching and effacing E. coli (AEEC) were also detected from carcasses by colony hybridization after pre-enrichment and plating on sorbitol MacConkey agar using eae, stx1 and stx2 probes. Thirty carcasses (13%) on the 230 analysed harboured at least one colony positive for one of the tested probes. These positive carcasses were different from those positive for E. coli O157. Sixty-six colonies (2·9%) positive by colony hybridization were isolated. The majority (60·6%) of the positive strains harboured an enteropathogenic E. coli -like pathotype (eae+ stx,). Only three enterohaemorrhagic E. coli (EHEC)-like (eae+ stx1+) colonies were isolated from the same carcass. These strains did not belong to classical EHEC serotypes. Conclusions:, In this study, the global hygiene of the slaughterhouse was low, as indicated by the high level of E. coli count. The prevalence of both E. coli O157 and other AEEC was also high, representing a real hazard for consumers. Significance and Impact of the Study:, This is the first study of this type in Algeria, which indicates that the general hygiene of the slaughterhouse must be improved. [source] Which are the polyphosphate accumulating organisms in full-scale activated sludge enhanced biological phosphate removal systems in Australia?JOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2006M. Beer Abstract Aims:, To see if the compositions of the microbial communities in full scale enhanced biological phosphorus removal activated sludge systems were the same as those from laboratory scale sequencing batch reactors fed a synthetic sewage. Methods:, Biomass samples taken from nine full scale enhanced biological phosphate removal (EBPR) activated sludge plants in the eastern states of Australia were analysed for their populations of polyphosphate (polyP)-accumulating organisms (PAO) using semi-quantitative fluorescence in situ hybridization (FISH) in combination with DAPI (4,-6-diamidino-2-phenylindole) staining for polyP. Results:, Very few betaproteobacterial Rhodocyclus related organisms could be detected by FISH in most of the plants examined, and even where present, not all these cells even within a single cluster, stained positively for polyP with DAPI. In some plants in samples from aerobic reactors the Actinobacteria dominated populations containing polyP. Conclusions:, The PAO populations in full-scale EBPR systems often differ to those seen in laboratory scale reactors fed artificial sewage, and Rhodocyclus related organisms, dominating these latter communities may not be as important in full-scale systems. Instead Actinobacteria may be the major PAO. Significance and Impact of the Study:, These findings illustrate how little is still known about the microbial ecology of EBPR processes and that more emphasis should now be placed on analysis of full-scale plants if microbiological methods are to be applied to monitoring their performances. [source] Resident bacteria in a mixed population of rhesus macaque (Macaca mulatta) monkeys: a prevalence studyJOURNAL OF MEDICAL PRIMATOLOGY, Issue 6 2009C.A. Carrier Abstract Background, Microflora populations residing in oropharyngeal and gastrointestinal sites defend against pathogenic bacterial colonization. Perturbations in these microbial communities may allow opportunistic pathogenic bacteria to establish themselves and cause morbidity and mortality from sepsis particularly after stressful experimental procedures. This study determined the prevalent facultative bacteria in a resident population of Macaca mulatta prior to use in experimentally induced immunosuppressive radiation studies. Methods, Standard microbiological methods were used to assess prevalent facultative bacteria in the oropharynx and rectum of 24 male M. mulatta. Results, The majority of the bacteria isolated from the oropharyngeal and rectal sites were gram-positive cocci. Species of Staphylococcus and Streptococcus predominated in all samples. Few gram-negative bacteria were isolated. Conclusions, Bacteriological assessment is recommended to identify predominant bacterial species to be prepared to provide appropriate antimicrobial therapy in non-human primates that are expected to undergo stressful immunocompromising procedures. [source] Some multidisciplinary techniques used in MIC studiesMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 7 2006W. Wang Abstract This paper presents a review of the application of microbiological methods, chemical analysis and surface analysis techniques in studying the microbially influenced corrosion (MIC) process of metals and their alloys. As a multidisciplinary research, some techniques used to study biofilm-related problems are also discussed in this paper, as potential tools in this field. [source] A new checkerboard panel for testing bacterial markers in periodontal diseaseMOLECULAR ORAL MICROBIOLOGY, Issue 1 2006G. Dahlén Background/aims:, Various microbiological methods have been used for testing bacterial markers for periodontitis and periodontal disease progression. Most studies have used only a limited number of well recognized bacterial species. The purpose of the present study was to evaluate the association of 13 more recently identified bacterial species in a new panel in comparison with 12 previously more recognized periodontotopathogens (,old panel') using the ,checkerboard' DNA,DNA hybridization method. Methods:, Fifty individuals were chosen who showed at least one site with a probing pocket depth of 6 mm or more (disease) and bleeding on probing and at least one site with a probing pocket depth of 3 mm and without bleeding on probing (health). One diseased and one healthy site on each individual were sampled with the paperpoint technique and the samples were processed in the checkerboard technique against deoxigenin-labeled whole genomic probes to 25 subgingival species representing 12 well recognized and 13 newly identified periodontitis associated species. Results:, Twenty-four (out of 25) species were detected more frequently in the subgingival plaque of diseased than healthy sites both at score 1 (> 104) and score 3 (> 105). A significant difference at the higher score (score 3) was noticed for all species of the old panel except for three (Streptococcus intermedius, Selenomonas noxia, and Eikenella corrodens). Of the species in the new panel only Prevotella tannerae, Filifactor alocis, and Porphyromonas endodontalis showed a statistical significant difference between diseased and healthy sites. Conclusion:, It was concluded that P. tannerae, F. alocis, and P. endodontalis should be added to the 12 species used for routine diagnostics of periodontitis-associated bacterial flora. [source] Occurrence of Cryptococcus spp. in excreta of pigeons and pet birdsMYCOSES, Issue 1-2 2000Kielstein In pooled samples of faeces from 25 pet bird flocks in Thuringia, a high rate of contamination with Cryptococcus neoformans var. neoformans was found. The prevalence of Cr. neoformans in the bird-breeding establishments correlated with the numbers of the different pet bird species in these flocks. The differentiation between varieties of Cr. neoformans by means of proline assimilation and canavanine resistance detection as well as with the aid of Cr. neoformans factor sera, polymerase chain reaction (PCR) fingerprinting, sequencing of PCR products as well as Fourier transform infrared spectroscopy showed uniform results which also corresponded to the serological differentiation between serovars A and D. A predominance of serovar A could be observed among the pet bird breeding flocks. This corresponded to the frequency distribution of serovars A and D in cases of human diseases in Germany. In 50% of the samples of pigeon excreta examined (n=30) in Innsbruck (Austria), Cryptococcus albidus could be isolated but not Cr. neoformans. However, this Cryptococcus species is of minor pathogenetic importance for man. Cryptococcus albidus may be clearly distinguished from Cr. neoformans by means of microbiological methods, PCR and Fourier transform infrared spectroscopy. [source] Microbial contaminants in food: a big issue for a working group of the MoniQA NoE projectQUALITY ASSURANCE & SAFETY OF CROPS & FOOD, Issue 2 2009A. Hoehl Abstract Introduction The MoniQA Network of Excellence is an EC funded project working towards the harmonization of analytical methods for monitoring food quality and safety along the food supply chain. This paper summarises both the structure and tasks of the working group on microbial contaminants within the MoniQA NoE and specifically focuses on harmonisation strategies important in the microbiological analysis of food. Objectives There is a need for rapid microbiological methods in order to quickly and efficiently identify harmful pathogens in food sources. However, one of the major problems encountered with many new methods is their market acceptance, as they have to pass extensive validation/standardisation studies before they can be declared as official standard methods. Methods The working group on microbiological contaminants aims to contribute towards speeding up these prerequisites by collecting information on food law, quality assurance, quality control, sampling, economic impact, measurement uncertainty, validation protocols, official standard methods and alternative methods. Results The present report provides an overview of currently existing methodologies and regulations and addresses issues concerning harmonisation needs. One of the deliverables of the working group is the development of extended fact sheets and reviews based on relevant ,hot' topics and methods. The selection of food borne analytes for these fact sheets have been selected based on global, local and individual parameters. The working group has identified 5 groups of stakeholders (governmental bodies, standardisation/validation organisations, test kit/equipment manufacturers, food industry and consumers). Conclusion Current challenges of food microbiology are driven by new analytical methods, changes in the food market and altered consumer desires. The MoniQA NoE is contributing in overcoming these risks and challenges by providing a profound platform on microbiological rapid methods in food analysis to all stakeholders and it is expected that strong interaction within the network and beyond will foster harmonization. [source] Let them fly or light them up: matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry and fluorescence in situ hybridization (FISH),APMIS, Issue 11-12 2004BIRGITTA SCHWEICKERT This review focuses on clinical bacteriology and by and large does not cover the detection of fungi, viruses or parasites. It discusses two completely different but complementary approaches that may either supplement or replace classic culture-based bacteriology. The latter view may appear provocative in the light of the actual market penetration of molecular genetic testing in clinical bacteriology. Despite its elegance, high specificity and sensitivity, molecular genetic diagnostics has not yet reached the majority of clinical laboratories. The reasons for this are manifold: Many microbiologists and medical technologists are more familiar with classical microbiological methods than with molecular biology techniques. Culture-based methods still represent the work horse of everyday routine. The number of available FDA-approved molecular genetic tests is limited and external quality control is still under development. Finally, it appears difficult to incorporate genetic testing in the routine laboratory setting due to the limited number of samples received or the lack of appropriate resources. However, financial and time constraints, particularly in hospitals as a consequence of budget cuts and reduced length of stay, lead to a demand for significantly shorter turnaround times that cannot be met by culture-dependent diagnosis. As a consequence, smaller laboratories that do not have the technical and personal equipment required for molecular genetic amplification techniques may adopt alternative methods such as fluorescence in situ hybridization (FISH) that combines easy-to-perform molecular hybridization with microscopy, a technique familiar to every microbiologist. FISH is hence one of the technologies presented here. For large hospital or reference laboratories with a high sample volume requiring massive parallel high-throughput testing we discuss matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF) of nucleic acids, a technology that has evolved from the post-genome sequencing era, for high-throughput sequence variation analysis (1, 2). [source] Differential diagnosis of acute central nervous system infections in children using modern microbiological methodsACTA PAEDIATRICA, Issue 8 2009Pasi Huttunen Abstract Aim:, Except bacterial meningitis, the agents causing acute central nervous system (CNS) infections in children are disclosed in only approximately half of the cases, and even less in encephalitis. We studied the potential of modern microbiological assays to improve this poor situation. Methods:, In a prospective study during 3 years, all children attending hospital with suspected CNS infection were examined using a wide collection of microbiological tests using samples from the cerebrospinal fluid, serum, nasal swabs and stool. Results:, Among 213 patients, 66 (31%) cases suggested CNS infection and specific aetiology was identified in 56 patients. Of these microbiologically confirmed cases, viral meningitis/encephalitis was diagnosed in 25 (45%), bacterial meningitis in 21 (38%) and neuroborreliosis in 9 (16%) cases while 1child had fungal infection. In meningitis patients, the causative agent was identified in 85% (35/41) cases and in encephalitis in 75% (12/16). The most common bacteria were Streptococcus agalactiae, Streptococcous pneumonie and Neisseria meningitidis, while the most frequently detected viruses were enteroviruses and varicella zoster virus. Conclusion:, In 75% to 85% of paediatric CNS infections, specific microbiological diagnosis was obtained with modern laboratory techniques. The results pose a basis for prudent approach to these potentially serious diseases. [source] High-throughput epidemiologic typing in clinical microbiologyCLINICAL MICROBIOLOGY AND INFECTION, Issue 2 2003A. Van Belkum Mapping, and ultimately preventing, the dissemination of infectious agents is an important topic in public health. Newly developed molecular,microbiological methods have contributed significantly to recent advances in the efficient tracking of the nosocomial and environmental spread of microbial pathogens. Not only has the application of novel technologies led to improved understanding of microbial epidemiology, but the concepts of population structure and dynamics of many of the medically significant microorganisms have advanced significantly also. Currently, genetic identification of microbes is also within the reach of clinical microbiology laboratory professionals including those without specialized technology research interests. This review summarizes the possibilities for high-throughput molecular,microbiological typing in adequately equipped medical microbiology laboratories from both clinical and fundamental research perspectives. First, the development and application of methods for large-scale comparative typing of serially isolated microbial strains are discussed. The outcome of studies employing these methods allows for long-term epidemiologic surveillance of infectious diseases. Second, recent methods enable an almost nucleotide-by-nucleotide genetic comparison of smaller numbers of strains, thereby facilitating the identification of the genetic basis of, for instance, medically relevant microbiological traits. Whereas the first approach provides insights into the dynamic spread of infectious agents, the second provides insights into intragenomic dynamics and genetic functionality. The current state of technology is summarized, and future perspectives are sketched. [source] | ||||||||||