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PubMed1992

NIH conference. Gastrointestinal infections in AIDS.

As the largest lymphoid organ in the body, the gastrointestinal tract is a potential reservoir for human immunodeficiency virus (HIV), the causative agent of the acquired immunodeficiency syndrome (AIDS), and it is an important site for HIV-induced immunodeficiency. The resulting defects in cellular and humoral defense mechanisms predispose the gastrointestinal tract to a spectrum of viral, fungal, bacterial, and protozoan pathogens that cause relentless morbidity and, in some cases, death. With a thorough diagnostic evaluation, physicians can identify one or more of these pathogens in a majority of patients with AIDS who have gastrointestinal symptoms. The identification of enteric pathogens in patients with AIDS is important because an increasing array of therapeutic regimens is becoming available to treat many of these infections.

Acquired Immunodeficiency Syndrome↗
PubMed2002

Pseudomonas viridiflava and P. syringae--natural pathogens of Arabidopsis thaliana.

We report the isolation and identification of two natural pathogens of Arabidopsis thaliana, Pseudomonas viridiflava and Pseudomonas syringae, in the midwestern United States. P. viridiflava was found in six of seven surveyed Arabidopsis thaliana populations. We confirmed the presence in the isolates of the critical pathogenicity genes hrpS and hrpL. The pathogenicity of these isolates was verified by estimating in planta bacterial growth rates and by testing for disease symptoms and hypersensitive responses to A. thaliana. Infection of 21 A. thaliana ecotypes with six locally collected P. viridiflava isolates and with one P. syringae isolate showed both compatible (disease) and incompatible (resistance) responses. Significant variation in response to infection was evident among Arabidopsis ecotypes, both in terms of symptom development and in planta bacterial growth. The ability to grow and cause disease symptoms on particular ecotypes also varied for some P. viridiflava isolates. We believe that these pathogens will provide a powerful system for exploring coevolution in natural plant-pathogen interactions.

Arabidopsis↗
PubMed2003

Rapid identification of Rhodococcus equi by a PCR assay targeting the choE gene.

The actinomycete Rhodococcus equi is an important pathogen of horses and an emerging opportunistic pathogen of humans. Identification of R. equi by classical bacteriological techniques is sometimes difficult, and misclassification of an isolate is not uncommon. We report here on a specific PCR assay for the rapid and reliable identification of R. equi. It is based on the amplification of a fragment of the choE gene encoding cholesterol oxidase. The choE-based PCR was assessed by using a panel of strains comprising 132 isolates from different sources and of different geographical origins, all initially identified biochemically as R. equi, and 30 isolates of representative non-R. equi actinomycete species, including cholesterol oxidase producers. The expected 959-bp amplicon was observed only with R. equi isolates, as confirmed by sequencing of a variable region of the 16S RNA gene from a random sample of 20 PCR-positive isolates. All R. equi isolates gave a positive choE-based PCR result, which correlated with a high degree of conservation of the choE gene. Three of the 132 strains originally identified as R. equi were negative for the choE gene, and subsequent analysis of their 16S RNA gene sequences confirmed that they belonged to other bacterial species (Dietzia maris, Mycobacterium peregrinum, and Staphylococcus epidermidis). All non-R. equi isolates were negative by the choE-based PCR. ATCC 21387, the only known isolate of Brevibacterium sterolicum, gave a 959-bp amplicon whose DNA sequence was virtually identical to that of R. equi choE. Comparison of the 16S RNA genes indicated that ATCC 21387 should be considered an R. equi isolate.

Actinomycetales Infections↗
PubMed1987

Antigenic relationship between the animal and human pathogen Pythium insidiosum and nonpathogenic Pythium species.

Identification of the newly named pathogenic oomycete Pythium insidiosum and its differentiation from other Pythium species by morphologic criteria alone can be difficult and time-consuming. Antigenic analysis by fluorescent-antibody and immunodiffusion precipitin techniques demonstrated that the P. insidiosum isolates that cause pythiosis in dogs, horses, and humans are identical and that they were distinguishable from other Pythium species by these means. The immunologic data agreed with the morphologic data. This indicated that the animal and human isolates belonged to a single species, P. insidiosum. Fluorescent-antibody and immunodiffusion reagents were developed for the specific identification of P. insidiosum.

Animals↗
PubMed2003

[Vulvovaginal candidiasis and sensitivity of pathogens to antimycotics].

OBJECTIVE: Analysis of the prevalence and species representation of pathogenic yeasts in patients with vulvovaginal candidiasis. Determination of in vitro susceptibility of yeast isolates to clinically used antimycotic agents. DESIGN: A retrospective clinical study of patients with positive vaginal cultures for the presence of pathogenic yeast species. SETTING: I. gynekologicko-pôrodnícka klinika LF UK a FN, Zochova 7,811 03 Bratislava, Slovenská republika. METHODS: Identification of yeast pathogens on the chromogenic medium CHROMagar CANDIDA and with API-CANDIDA identification system. In vitro susceptibility assays of clinical yeast isolates to antifungal agents using the plate dilution method, NCCLS method and ATB-FUNGUS test system. RESULTS: The highest prevalence of vulvovaginal candidasis was found in women aged between 20-30 years. Candida albicans was the most commonly identified species of pathogenic yeasts (87.4%). Of the non-albicans species, C. glabrata (6.3%) was the most prevalent species. C. glabrata and C. krusei clinical isolates were found to be generally less susceptible to several antifungals in vitro as compared to C. albicans strains. A minimal number of resistant yeast isolates was observed for econazole, clotrimazole and nystatin. A relatively high number of resistant strains was observed for some other azole antifungals (miconazole, ketoconazole, itraconazole, fluconazole). CONCLUSION: A successful treatment of vaginal mycotic infections requires the results of the microbiological analyses. They will bring evidence to a physician of the presence and fate of the pathogen, of its sensitivity to antifungals, both of which are essential for the rational and successful therapy of Candida vaginitis.

Adult↗
PubMed1994

Pathogenic potential of lactobacilli.

Lactobacilli are often considered to be commensal or beneficial participants in human microbial ecology and considerable research is being carried out into the effects of the use of lactobacilli as additives in both human and animal diets. However, lactobacilli also cause some human diseases (e.g. dental caries, rheumatic vascular disease, septicaemia and infective endocarditis (IE)), and have recently been identified as potential emerging pathogens in elderly and immunocompromised patients, particularly those receiving broad spectrum antibiotic therapy. The identification of potential pathogenic traits amongst lactobacilli will therefore facilitate the use of the organisms for probiotic purposes. The ability to aggregate human platelets is considered to be a possible pathogenic trait in the progression of IE. A comparison of bacterial cell surface properties amongst L. rhamnosus strains showed that platelets were aggregated by 5/5 IE strains and 8/16 laboratory strains. For the L. paracasei subsp. paracasei strains the respective numbers were 2/5 and 2/9. However two strains, morphological mutants of a non-aggregating strain, which had been re-isolated after passaging through rats were found to aggregate platelets. No loss of aggregating function occurred on extensive subculturing of IE strains. Aggregation also occurred with 11/14 strains for five other species, namely, Lactobacillus acidophilus, Lactobacillus fermentum, Lactobacillus oris, Lactobacillus plantarum and Lactobacillus salvivarius, with each species being represented indicating that the property is not uncommon in the genus. A comparison of IE and oral isolates of L. rhamnosus and L. paracasei subsp. paracasei and seven other Lactobacillus species, has shown that the binding of both fibronectin and fibrinogen by lactobacilli is greatly increased, up to 50 fold, when the pH is reduced from 7.0 to 5.0. Re-exposing the lactobacilli to a neutral pH environment releases most of the bound proteins, but the amount still remaining bound to the cell is several times more than is bound at neutral pH. Lactobacilli will also bind to the proteins that make up the extracellular matrix of endothelial cells. Lactobacilli bound significantly better to collagen types I and V than to types III and IV (p < 0.01). Further, strains isolated from IE cases, particularly L. rhamnosus strains, bound significantly better to types I and V than did 'normal' strains (p < 0.02). Type V collagen has been demonstrated at the sites of endothelial damage. Thus the binding of lactobacilli, particularly L. rhamnosus to these collagen types may be of importance in the early stages of colonization of the damaged heart valve.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2004

[Bacterial infections in chronic otitis media--usefulness of molecular diagnostics based on PCR method].

Infections in chronic otitis media (COM) are common, and identification of their pathogen is difficult, what is proven by high rate of negative results of bacteriological examinations. This fact may be explained by two factors: it is difficult to obtain a reliable material for culture and classic methods of bacteriological cultures may be of low sensitivity. Amplification of bacterial DNA in PCR is an examination, that leads to a higher effectiveness and sensitivity of bacteriological tests. The authors present material of 53 patients with COM, previously untreated, in which bacteriological examinations by classic and molecular PCR method were performed. The results of both methods were compared. In classic method the presence of pathogens was observed in 46 of 53 cases (86.8%). The most often isolated bacteria were Pseudomonas aeruginosa (52.8% of the cases), Staphylococcus aureus (15.1%), Peptostreptococcus sp. and Fusobacterium sp. (11.3% of the cases each) and Proteus mirabilis (7.5%). In 7 cases (13.2%) bacteriological results were negative. Using molecular diagnostic of PCR, the presence of Pseudomonas aeruginosa was observed in 42 cases (79.2%). Isolated strains of P. aeruginosa were epidemiologically unrelated (93.7% of isolates), what was proven in PCR-finger-printing technique. The authors stated that predominant aerobes pathogens in COM are P. aeruginosa and S. aureus and the PCR technique for identification of bacterial DNA presence is very sensitive and allows to precipitate diagnostics of patients with COM. Combination of classical bacteriological tests with PCR technique may be very helpful in estimation bacteriological condition of patients with COM.

Adolescent↗
PubMed1993

[Therapy of infections in gynecology].

Infections of the female genitals are among the most common conditions seen by primary care physicians. Approximately 75% of all women experience at least one episode of vaginitis during their reproductive life. Bacterial flora of the female genital tract is complex and dynamic. Those organisms which may cause gynecological infections in the appropriate setting are often present at a different stage in the woman's life as normal flora. The treatment of gynecological infections is dependent on the symptoms of the patient, the pathogen, and the medical history with regard to recurrences of the same disease. Since identification of the pathogen is often difficult, empirical therapy is administered frequently, which requires detailed knowledge of the most common bacterial pathogens and the resistance pattern of these organisms. An accurate initial diagnosis is the best basis for appropriate therapy, especially in view of the fact that once empirical antibiotic therapy has been administered, signs and symptoms are modified and the site of infection is rendered much more obscure.

Anti-Bacterial Agents↗
PubMed1990

Numerical classification and identification of Bacillus sphaericus including some strains pathogenic for mosquito larvae.

Ninety-one strains of Bacillus sphaericus, including representatives of all the established DNA homology groups, related round-spored and oval-spored species, and six strains pathogenic for mosquito larvae, were examined for 155 characters. Numerical analyses (Jaccard coefficient/average linkage clustering) based on the 88 variable features revealed 14 clusters at the 79% similarity level that contained more than one strain and 17 single member clusters. All insect pathogenic strains were recovered in a single cluster and the classification was in accord with an established classification based on DNA sequence homology. Two frequency matrices for probabilistic identification were constructed and tested. A comprehensive matrix comprising 14 mesophilic, round-spored taxa and 27 tests gave good results for identification of hypothetical median organisms, cluster overlap and identifications of representative strains (based on data generated in the classification study). Reference strains for the 14 taxa and eight additional insect pathogenic strains were examined for the 27 tests and were correctly identified with high scores using this matrix. A second matrix comprising seven taxa and 13 tests also performed well in the theoretical evaluation and correctly identified the reference strains and insect pathogenic strains.

Animals↗
PubMed2006

Pathogen-derived immunomodulatory molecules: future immunotherapeutics?

The identification of molecules from various pathogens that modulate innate and/or adaptive immunity is a dynamic and rapidly developing area of research. These immunomodulatory molecules (IM) have been optimized during pathogen-host co-evolution, and have a potential application as novel immunotherapeutics. In this review, we illustrate the use of pathogen IM that have been produced as recombinant proteins, with different modes of modulatory activity, and discuss their potential to modulate undesirable immune responses in human diseases.

Animals↗
PubMed2002

[Characterization of pathogenic bacteria of the cupped oyster Crassostrea gigas].

The French mollusc production is mainly based on the Pacific cupped oyster, Crassostrea gigas. Since 1991, outbreaks of mass mortality of juveniles are reported during the summer period. These outbreaks are a major concern of oyster industry. Several studies have established given bacterial strains to be pathogenic for bivalve species, including oysters. Here we present a study of mortality outbreaks of C. gigas, as initiated in 1995. In a first step, bacterial strains were isolated during mass mortality outbreak and were biochemically characterised. Among the isolated strains, some strains of Vibrio splendidus biovar II were found to be pathogenic by means of experimental challenge of oyster juveniles. In the second step, a genotypical identification of the pathogenic strain was undertaken, based on 16S RNA sequences and phylogenetic analysis. It confirmed that the pathogenetic strain belonged to Vibrio splendidus biovar II.

Animals↗
PubMed1997

Molecular diagnostics for dairy-borne pathogens.

Advances in diagnostic assays based on nucleic acids will revolutionize the ability of the industry to maintain the safety of dairy foods. Two complementary assay formats are explored, one of which permits the rapid detection of bacterial pathogens and the other the identification of reservoirs of these pathogens. The first format is an assay based on the polymerase chain reaction that employs homogeneous detection (TaqMan polymerase chain reaction detection; Perkin Elmer, Applied Biosystems Division, Foster City, CA) of the target sequence. This assay has been applied to the detection of Listeria monocytogenes. A primary problem with current assays that are based on polymerase chain reaction is the complexity of sample handling and the quantification of the initial target number. This fluorogenic assay takes advantage of the endogenous 5',3'-endonuclease activity in Taq DNA polymerase. Approximately 100 samples can be analyzed in 2 to 3 h with a sensitivity of < 50 cells and a dynamic range of > 1000-fold. The TaqMan polymerase chain reaction detection assay is a robust format that is readily applicable to a wide array of other pathogens found in foods and in the environment. The second format is an instrument for automated ribosomal RNA analysis (Riboprinter; DuPont, Wilmington, DE) that can be used to locate the reservoirs harboring the bacterial pathogen. Use of this typing method it has been shown that, although a number of different ribotypes can be isolated from a single environmental sample, only a selected number of these strains apparently have the ability to cause disease. The future of food microbiology lies in the development and integration of molecular methods that can be automated into a testing regimen that extends from the farm to finished products.

Bacterial Infections↗
PubMed1999

Enteric pathogens and their isolation at a cancer hospital in Pakistan.

Diarrhoeal diseases remain a major cause of mortality and morbidity in developing countries. However, due to lack of funds, supply problems and some inexperience, some laboratories have difficulty identifying a causative agent in stool samples. In the year following the opening of the Shaukat Khanum Memorial Cancer Hospital and Research Centre in Lahore, Pakistan, the microbiology department had not isolated a single enteric pathogen. From January 1996, new culture techniques were introduced, with a resulting increase (10%) in identification of these pathogens. In addition, the introduction of formol-ether concentration made a significant contribution to the number of intestinal parasites seen. This report demonstrates how simple microbiology methods made a difference to the running of the department and, ultimately, to the patients.

Developing Countries↗
PubMedDate not supplied

Detection of etiological agent for cholera by PCR protocol.

BACKGROUND: PCR protocol for Vibrio cholerae, the causative agent of the diarrheal disease cholera has been described in this report. We report the detection of Vibrio species in drinking water samples in a duplex PCR reaction. The target loci used in the study were ctxA and tcpA. The sensitivity and efficiency of detection of this protocol can be applied in epidemic conditions, wherein monitoring of target organisms is very crucial. MATERIAL AND METHODS: Single step thermocycling programs have been reported for amplification of specific target loci. We have demonstrated that a gradient multi-step thermocycling program is more efficient in improving the sensitivity of detection by PCR. The method for preparation of template DNA from environmental sample uses filtration of water followed by harvesting the possible bacterial residue. This was further treated with proteinase K and heat to yield DNA compatible for PCR. The protocol was optimized for amplification of target loci from standard strains as well as from environmental water samples. RESULTS: The method can simultaneously detect two different loci of Vibrio cholerae in a single reaction. The sensitivity of detection achieved for the pathogen was 100 cells per reaction. The specificity of the primers was demonstrated by spiking the reaction with non-specific template. The developed protocol was successfully extended to environmental samples. CONCLUSIONS: The developed duplex PCR protocol allows the simultaneous detection of two genetic loci of the target pathogen from water samples. This enhances the efficiency of detection and provides a sensitive tool for the rapid detection of the pathogen that can be useful in epidemic conditions where the time factor involved in the identification of target pathogen is very crucial.

Bacterial Outer Membrane Proteins↗
PubMed1993

The laboratory diagnosis of mycobacterial diseases.

Recent developments in diagnostic mycobacteriology are surveyed with emphasis on laboratory capabilities relevant to the more rapid and accurate detection and identification of mycobacterial pathogens. Some terminologic problems are reviewed, and some newly recognized mycobacterial pathogens are discussed. Newer methodologies presented in some detail include the radiometric technique for detection, identification, and susceptibility testing of mycobacteria, and the use of DNA probes for identification of mycobacterial species and species complexes. The utility of other developing methodologies, such as polymerase chain reaction technology, analysis of body fluids for tuberculostearic acid, and the use of ELISA are also assessed.

Bacteriological Techniques↗
PubMed2006

[Isolation and identification of Streptococcus suis serotype 2 from sick-pig samples of Sichuan province].

Streptococcus suis serotype 2 (SS2) is a major pathogen frequently associated with infections in pigs. There are presently 35 serotypes of S.suis (serotype 1 to 34 and serotype 1/2) recognized on the basis of capsular antigens. Few people were reported to infect with SS2 in the past years. However, an accidental case happened in Sichuan province of China in 2005. Some people got ill and died, and all of them were closely contacted with sick pigs. Based on clinical features and epidemiologic data, this case could be caused by SS2 infection. Liver, spleen, kidney, lung and serum samples were collected and used for pathogen isolation and identification in laboratory, three strain bacteria were isolated. The three strains of SS2 showed typical morphology of SS2 on blood agar and under microscope with Gram stain. They were also agglutinated with standard serum of SS2. Biochemical characteristics of the three bacteria were tested using API 20 strep and analyzed by API software (version 3.3), results showed they were SS2. Four pairs of primer were designed, which were exactly matched the extracellular factor gene, muraminidase released protein gene, capsular polysaccharides gene and 16S rRNA gene respectively. These primers were used on polymerase chain reaction (PCR), and the PCR products were 626bp, 885bp, 487bp and 297bp on agarose gel, respectively. Drug sensitivity test were also done and results showed that they were sensitive to cefazolin, clindamycin, erythromycin, levofloxacin, nitrofurantoin, penicillin-G, and vancomycin and resistive to tetracycline. Balb/c mice infected with the isolated SS2 strain showed swelling in stomach and intestine, cyanochroia at mouth and suggillation under skin, which were similar to the clinical features of patients. Streptococcus suis serotype 2 were also found on lung sheeting sample under microscope with Gram stain. Rabbits infected with the isolated SS2 showed the similar clinical features with mice.

Animals↗
PubMed2001

A study of quality assessment in clinical microbiology performance of independent laboratories in Tokyo: 18-year participation in the Tokyo Metropolitan Government External Quality Assessment Program.

We evaluated the performance of independent microbiology laboratories in Tokyo over an 18-year period of participation in the external quality assessment (EQA) program, and we estimated the impact of the EQA program. The study design was a longitudinal retrospective analysis of performance, including isolation, identification, and antimicrobial susceptibility testing of bacteria from simulated patients' samples, in "open" surveys compared with "blind" surveys. Independent microbiology laboratories, licensed by the Tokyo Metropolitan Government, have been subject to mandatory evaluation by the EQA program since 1982. Survey reports, correspondence, annual guidance meetings, and inspections are used as quality improvement strategies. The performance for identification in "blind" surveys was significantly worse than that in "open" surveys (P < 0.001). Poorly performing laboratories had common features, including inadequate supervision by physicians and lack of familiarity with the impact of variations on the use of the standards. However, there were improvements in the performance of identification of some pathogens. The performance of susceptibility testing has not yet reached the relatively high level seen for identification. Some of the smaller laboratories have been gradually acquired by commercial chains operating outside Tokyo. The EQA program has established a role both in regard to laboratory improvement and as an educational tool. However, the program lags behind these of other developed countries in regard to the practical sciences. The main problems in regard to laboratory improvements are a shortage of human resources in clinical microbiology, lack of standardization of laboratory methods, and the pressures of financial constraints in the Japanese medical insurance system.

Data Collection↗
PubMed2004

Chips with everything: DNA microarrays in infectious diseases.

Two developments are set to revolutionise research in and clinical management of infectious diseases. First, the completion of the human genome project together with the sequencing of many pathogen genomes, and second, the development of microarray technology. This review explains the principles underlying DNA microarrays and highlights the uses to which they are being put to investigate the molecular basis of infectious diseases. Pathogen studies enable identification of both known and novel organisms, understanding of genetic evolution, and investigation of determinants of pathogenicity. Host studies show the complexities of development and activation of both innate and adaptive immunity. Host-pathogen studies allow global analysis of gene expression during pathogenesis. Microarray technology will accelerate our understanding of the complex genetic processes underlying the interaction between microorganisms and the host, with consequent improvements in the diagnosis, treatment, and prevention of infectious diseases.

Animals↗