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PubMed1998

[Expedition, experiment and expertise reflected in Robert Koch's assets].

Basic techniques in bacteriology provided the foundation for the success of experimental medicine. The combination of laboratory experiments and field studies consolidated bacteriology as a paradigm for the development of preventive strategies. Robert Koch's (1843-1910) contribution to this development is crucial in that he integrated the technical facilities of his era into microbiological research. The present study introduces various sources of Koch's assets which, in addition to manuscripts and letters, include also bacteriological slides and photographs. These relicts allow to reconstruct an example of the scientific process as a whole, to investigate his style and purpose as a scientist, and to follow Koch's strategy of visualisation with contemporary technical equipment. The example chosen is Koch's last expedition when the German government sent him to investigate the spreading of sleeping-sickness in Eastern Africa and to test "Atoxyl" as a specific remedy. Most case-studies and laboratory-research took place on the Sese-Islands in Lake Victoria and illustrate the extreme conditions in tropical Africa. The experiments searching for the etiological agent of sleeping-sickness--a typical disease only for central Africa--involved bacteriological slides which were to be the basis for further experimental results and the expertise expected of him.

Africa↗
PubMed1980

Indicator technique for antimetabolic toxin production by phytopathogenic species of pseudomonas.

A simple bacteriological technique involving inhibition zone production on a lawn of Escherichia coli was developed to detect antimetabolite toxin production by phytopathogenic species of Pseudomonas. It was established that the mechanism of E. coli inhibition paralleled that of phytotoxin-induced chlorosis of plant tissue. Derivatives of Pseudomonas tabaci and Pseudomonas phaseolicola which did not produce antimetabolite were readily identified by use of this technique. The presence of plasmid DNA in P. tabaci strains was demonstrated, but no physical evidence for plasmid involvement in tabtoxin production was found. The role of antimetabolite production in the pathogenicity of P. phaseolicola was also investigated. The method was extended to show that strains of P. maculicola, P. syringae, and P. coronofaciens also produce antimetabolites.

Journal Article↗
PubMed1984

Prophylactic regimens in colorectal surgery. Comparison between metronidazole used alone or in combination with either ampicillin or doxycycline.

Sixteen hospitals are participating in this study, that started in October 1982 and will be concluded when 456 patients have been admitted. The study includes patients eligible for elective colorectal surgery. Inclusion criteria, surgical techniques, definition of recognizable infection, sampling of specimens for bacteriological investigations, bacteriologic techniques, and evaluation criteria were standardized. Patients were divided into 2 main groups. Patients in Group 1 received either a single intravenous dose of 1500 mg metronidazole or this dose was combined with a single, intravenous dose of 6 g ampicillin. Patients in group 2 received either a single intravenous dose of 1500 mg metronidazole or this dose combined with a single intravenous dose of 400 mg doxycycline. Dosage regimens were allocated randomly. The current results concern 136 patients. Postoperative infections were seen in 6.7% of the patients receiving metronidazole alone, and 2.9% of the patients receiving metronidazole + ampicillin (Group 1). In Group 2, postoperative infection occurred in 17.1% of the patients receiving metronidazole alone, and in 2.7% of those receiving metronidazole + doxycycline.

Adult↗
PubMedDate not supplied

The implication of nitric oxide in the process of bacterial translocation.

Since there is increasing evidence indicating nitric oxide [NO] would play a role in sepsis, we decided to investigate whether this multifaceted mediator is directly implicated in the process of bacterial translocation. A total of 48 rats received intraperitoneal either Zymosan A (group Z) for systemic inflammation production or sodium chloride solution (controls); they were then further subdivided into three groups of eight animals each, being given, through the tail vein: L-NAME (N-nitro-L-arginine] for inhibition of NO production; SNP (sodium nitroprusside) as NO donor; or sodium chloride as control. After 2 h, the mesenteric lymph node complex was excised, under sterile conditions, and, using standard bacteriological techniques, bacterial translocation was assessed as colony forming units per gram of tissue (CFU/g). Statistical evaluation of the bacteriological data revealed a significant increase of bacterial translocation in all rats subjected to systemic inflammation (group Z) versus controls (P = 0.01) Control rats that were subjected to L-NAME treatment exhibited a statistically significant increase (P = 0.001) in CFU/g compared to sodium chloride treated rats, while SNP treatment revealed no difference in relation to sodium chloride treated rats. Group Z rats, subjected to L-NAME treatment, similarly exhibited a statistically significant increase (P = 0.01) in CFU/g compared to sodium chloride treated rats, while SNP treatment led to a statistical increase of bacterial translocation in relation to sodium chloride treated rats (P = 0.05). The results of this study lead us to suggest that NO appears to participate in the process of bacterial translocation.

Animals↗
PubMed1975

[The microbial flora in the digestive tract of the monogastric and its effect on the nutritional metabolism of the host].

The purpose of the present article is to give a survey of present knowledge of the ecological relationships between the various bacterial populations composing the microflora of the digestive tract of the host animal. Analysis of the relationships can be made with the aid of recent techniques: utilization of axenic animals (germ-free) and of gnotoxenic animals inoculated with known bacterial populations; perfecting of bacteriological techniques for the quantitative differential analysis of the various bacterial populations in the digestive tract, especially in the case of strictly anaerobic species. Some characteristics of the equilibrium between the various bacterial populations in the different segments of the gastro-intestinal tract have been described as well as some of the mechanisms which regulate this equilibrium. These mechanisms either imply interactions between bacteria or the action of the host animal and the environment on the microflora. Lastly, various examples concerning the action of the microflora in the digestive tract on the nutritional physiology of the host animal are given; action on the anatomy of the digestive tract and on the metabolism of carbohydrates, proteins, lipids and vitamins.

Animals↗
PubMed1984

[Immunoenzyme method in the diagnosis of meningococcal infections].

The materials on the development and use of the test system, based on the enzyme-linked immunosorbent assay (ELISA) and intended for the detection of specific group A and C meningococcal polysaccharides and type b Haemophilus influenzae polysaccharide in the spinal fluid of patients, are presented. In this work commercial preparations manufactured in the USSR were used, and all parameters of the assay were developed on the basis of these preparations. The study was made on the samples of spinal fluid from 410 patients; of these, 203 had meningococcal infection, 57 had purulent bacterial meningitides and 150 had other diseases (acute respiratory diseases, influenza, etc.). As demonstrated by the results of this study, ELISA proved to be a highly specific and sensitive technique. In the investigation of the spinal fluid samples from the patients with meningococcal infection the use of ELISA with bacteriological techniques increased the number of positive results to 67%; with countercurrent electrophoresis, to 78%; and with bacterioscopy, to 83.8%. ELISA is recommended for practical use as an auxiliary laboratory technique and as a rapid method for the diagnosis of meningococcal infection.

Animals↗
PubMed2001

Prevalence of Streptococcus iniae in tilapia, hybrid striped bass, and channel catfish on commercial fish farms in the United States.

OBJECTIVE: To determine the prevalence of Streptococcus iniae in tilapia (Oreochromis spp), hybrid striped bass (Morone chrysops X M saxatilis), and channel catfish (Ictalurus punctatus) on commercial fish farms in the United States. ANIMALS: 1,543 fish (970 tilapia, 415 hybrid striped bass, and 158 channel catfish). PROCEDURES: The dry-swab technique was used for collection of specimens for streptococcal isolation. Specimens were shipped by overnight delivery and processed by use of standard bacteriologic techniques. RESULTS: Streptococcus iniae was not isolated from market-size channel catfish. Prevalence in tilapia and hybrid striped bass was 37 of 970 (3.81%) and 30 of 415 (7.23%), respectively. Prevalence by farm ranged from 0.0 to 27.4% for tilapia and 0.0 to 21.6% for hybrid striped bass. In tilapia, prevalence was lowest in market-size and nursery fish (4 of 239 [1.67%] and 3 of 339 [0.88%], respectively), with an increase in prevalence for fish in the grow-out stage (30 of 337 [7.96%]). For hybrid striped bass, prevalence was lowest in nursery and market-size fish (3 of 96 [3.12%] and 1 of 47 [2.12%], respectively) and highest in fish in the grow-out stage (26 of 272 [9.56%]). Prevalence in market-size tilapia and hybrid striped bass was 5 of 286 (1.75%). CONCLUSIONS AND CLINICAL RELEVANCE: Results of this study do not support the contention that S iniae is a serious public health threat associated with commercially raised fish; rather, it represents a limited risk for older or immunocompromised people who incur puncture wounds while handling and preparing fish.

Animals↗
PubMed2000

Experimental intravenous inoculation of Klebsiella rhinoscleromatis bacilli in albino rats: a histopathological and bacteriological study.

Scleroma, chronic specific granuloma of the nose and upper respiratory tract, is endemic in Egypt and many other countries. The exact pathogenesis of the disease as regards the aetiological role of Klebsiella rhinoscleromatis is contradictory. This work investigated the effect of experimental intravenous injection of K. rhinoscleromatis in albino rats to demonstrate that the micro-organism can fulfil Koch's postulates. Micro-organisms were isolated from biopsy specimens taken from nasal lesions of 10 patients in the granulomatous stage of scleroma. Specimens were subjected to bacteriological and histopathological examinations to confirm the diagnosis. A 100 microl volume of freshly prepared bacterial inoculum containing 10(8) cfu/ml was injected weekly in the tail vein of each of 30 albino rats for 5 consecutive weeks. Biopsy specimens were taken from sacrificed animals and subjected to bacteriological and histopathological examinations. Positive histopathological diagnosis of scleroma was reported in the nose of 66.7% of rats, the larynx of 46.7%, the lungs of 26.7% and liver of 20% of rats. Bacteriological techniques were successful in revealing K. rhinoscleromatis from the nose of 36.7% of rats, the larynx of 30% and the lungs of 20% of rats. Various techniques were carried out to demonstrate the micro-organisms in tissue sections. Two histochemical stains for bacteria were employed: silver and Periodic Acid Schiff (PAS) stains. Immunoperoxidase technique using Klebsiella capsular type 3 antiserum was applied. It gave positive results in 66.7% of the 6 stained liver sections in spite of negative bacteriological cultures. The histiocytic nature of the Mikulicz cells was confirmed using alpha-1 antitrypsin, an immunohistochemical marker of histiocytes, and by studying the ultrastructural features of Mikulicz cells using the transmission electron microscope.

Adult↗
PubMed1999

A national audit of the laboratory diagnosis of tuberculosis and other mycobacterial diseases within the United Kingdom.

In order to audit United Kingdom laboratory diagnostic and reference services including novel molecular methods for tuberculosis, a questionnaire was sent to laboratories submitting specimens to the PHLS Mycobacterium Reference Unit (MRU) and regional centres and to the Scottish Mycobacteria Reference Laboratory (SMRL) in 1996-7. Nationally, 67.2% of laboratories responded. Most UK laboratories were fully or conditionally CPA accredited and take part in the NEQAS proficiency scheme. On average only 3.3% of primary samples submitted for mycobacterial diagnosis in 1995 produced a mycobacterial culture from approximately half as many patients (that is, a mean of 1488 specimens producing 49 isolates from 23 patients). Potentially over 380,000 specimens are processed for mycobacteria in the UK each year. The majority of laboratories use 4% NaOH +/- NALC for specimen decontamination. Culture on solid media was used by most laboratories and 62.9% also use liquid media. Most laboratories incubated cultures for eight weeks. Few laboratories use molecular diagnostic methods. Laboratories were most likely to use molecular methods for diagnosing tuberculous meningitis and for specimens from immunocompromised patients, although usage was strongly influenced by cost. Within England and Wales 43.9% (47/107) and 56% (61/109) of laboratories wanted a rapid service for rifampicin resistance detection in M tuberculosis from immunocompetent and immunocompromised patients, respectively. In regard to a tuberculous meningitis service, 80.5% (43/112) and 84.3% (102/121) of laboratories wanted this service for immunocompetent and immunocompromised patients, respectively. The quality of reference services was rated as "very good"/"good" by 85.6% of respondents nationally. Rapid molecular amplification diagnostic services were established at the PHLS MRU for rifampicin drug resistance detection nationally and for tuberculous meningitis at the MRU.

Bacteriological Techniques↗