Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “pathogenicity classification”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 955 records · Page 53Linked to original sources
PubMed2000

The many faces of chlamydiae.

The application of modern research tools has broadened our understanding of the chlamydiae and their role in disease. Chlamydial genome analysis showed the presence of genes for ATP and peptidoglycan synthesis, contradicting the common belief that chlamydiae lack the ability to produce these compounds. Phylogenetic tree analysis suggests that chlamydiae could have evolved from an intracellular existence in amoebae. Newly discovered obligate intracellular organisms with chlamydia-like life-cycles have been classified as chlamydiae by rRNA homology with existing chlamydial species. A proposed new classification adds three new families to the order Chlamydiales as well as creates two genera and nine species within the family Chlamydiaceae. Chlamydiae are incriminated in an increasingly large spectrum of diseases both in humans and in animals. The emergence of multi-drug resistant C. trachomatis strains forewarns therapeutic problems with this organism. While C. pneumoniae remains a significant respiratory pathogen, the role it plays in the pathogenesis of atherosclerosis and ischaemic heart disease awaits definition.

Animals↗
PubMed1997

[Clinico-epidemiologic study of microtia].

Microtia is a congenital malformation characterized by total or partial absence of the whole auricle or any of its components, varying from a small auricle to the total absence (anotia). There may be associated atresia of the external auditory meatus. The frequency varies in different parts of the world between 0.4 and 5.5/10,000 newborns. In this paper we report the clinical and epidemiological characterization of this congenital malformation in a sample of 97.759 neonates born at the Ruíz y Páez Hospital in Ciudad Bolivar, Venezuela, between April 1978 and December 1994. A total of 38 patients with microtia were identified. The global frequency was 3.8 per 10,000/newborns. In 47.4% of the patients microtia was an isolated malformation and in 52.6% was associated to other malformations. Sixty three percent of the affected were males. The unilateral form was present in 81.5% of the cases, more frequently on the right side. The annual frequency of the defect was stable over the studied years. The clinical classification of the cases with associated malformations allowed us to establish that 18.4% of the cases correspond to developmental fields defects, associated to preauricular dimples and/or tags, 7.8% were cases of the facio-auriculo-vertebral spectrum and in 15.7% the microtia was part of a monogenic or chromosomal syndrome. In 10.5% it was not possible to define any etiological or pathogenic mechanism. The frequency obtained in this study for microtia shows intermediate values when compared with others reports from Latin America.

Abnormalities, Multiple↗
PubMed1986

[Taxonomy and systematics of pathogenic microorganisms].

The modern state of the problem of the systematics of microorganisms is analyzed and the data on the taxonomy of bacteria belonging to the family Enterobacteriaceae are presented. The importance of studies on the taxonomy of microorganisms is emphasized. These studies play a vital role in the development of diagnostic preparations and techniques for the identification of infective agents, as well as in the realization of epidemiological surveillance. Much attention is given to the works of Soviet microbiologists, discussing such problems as the unification of the classification scheme of dysentery bacteria, the intraspecific taxonomy of Francisella tularensis, the systematic position of Allomonas and the antigenic scheme of Hafnia, included into Bergey's Determinative Bacteriology, edition IX (1984).

DNA, Bacterial↗
PubMed1990

Postoperative wound infection in pediatric surgical patients: a study of 676 infants and children.

We conducted an epidemiologic study of postoperative wound infection in pediatric patients. Over a 14-month period, 676 patients who received an operative incision on the Pediatric Surgical service were entered. Demographic, nutritional, clinical, and laboratory data were collected. The patients were followed for development of postoperative wound infection. Cultures were taken from wounds to identify the offending organisms. Of the 676 patients, 137 were neonates, 197 infants, and 342 older children. Wound infection occurred in 17 patients (2.5%): 1 neonate (0.7%), 8 infants (4.1%), and 8 older children (2.3%). Infection rates according to wound classification were: clean 1.0%, clean-contaminated 2.9%, contaminated 7.9%, and dirty 6.3%. Heavily contaminated or dirty wounds were packed open in one third of cases, and allowed to heal by granulation. The largest group of wound infections followed operations on the gastrointestinal tract (10 patients, 267 operations, 3.7%). Staphylococcus aureus, Escherichia coli, and alpha hemolytic streptococcus were the most common wound pathogens. An increased rate of wound infection was associated with operative procedures longer than 1 hour, with the presence of an associated illness, and with emergency operations. Age, sex, nutritional status, and duration of preoperative hospital stay did not significantly alter the wound infection rate. It could be concluded that the incidence of wound infection was lower among pediatric surgical patients than the reported incidence in adult surgical patients. The greatest risk factors were those associated with local contamination of the surgical wound.

Age Factors↗
PubMed1998

Pharmacodynamic evaluation of factors associated with the development of bacterial resistance in acutely ill patients during therapy.

The selection of bacterial resistance was examined in relationship to antibiotic pharmacokinetics (PK) and organism MICs in the patients from four nosocomial lower respiratory tract infection clinical trials. The evaluable database included 107 acutely ill patients, 128 pathogens, and five antimicrobial regimens. Antimicrobial pharmacokinetics were characterized by using serum concentrations, and culture and sensitivity tests were performed daily on tracheal aspirates to examine resistance. Pharmacodynamic (PD) models were developed to identify factors associated with the probability of developing bacterial resistance. Overall, in 32 of 128 (25%) initially susceptible cases resistance developed during therapy. An initial univariate screen and a classification and regression tree analysis identified the ratio of the area under the concentration-time curve from 0 to 24 h to the MIC (AUC[0-24]/MIC) as a significant predictor of the development of resistance (P < 0.001). The final PK/PD model, a variant of the Hill equation, demonstrated that the probability of developing resistance during therapy increased significantly when antimicrobial exposure was at an AUC[0-24]/MIC ratio of less than 100. This relationship was observed across all treatments and within all organism groupings, with the exception of beta-lactamase-producing gram-negative organisms (consistent with type I beta-lactamase producers) treated with beta-lactam monotherapy. Combination therapy resulted in much lower rates of resistance than monotherapy, probably because all of the combination regimens examined had an AUC[0-24]/MIC ratio in excess of 100. In summary, the selection of antimicrobial resistance appears to be strongly associated with suboptimal antimicrobial exposure, defined as an AUC[0-24]MIC ratio of less than 100.

Acute Disease↗
PubMed2006

[HIV-1 diversity: a tool for studying the pandemic].

HIV-1 is remarkable for the diversity of strains comprising the HIV/AIDS pandemic. In the last decade, classification of viral variants as groups, subtypes, and circulating recombinant forms (CRF) and the observation of specific mutational patterns have become powerful tools for studying viral molecular dynamics. Monitoring the worldwide distribution of HIV-1 diversity has been used in both epidemiological surveillance programs and in reconstructing the history of regional epidemics. Specific patterns of virus spatial distribution also suggest differences in pathogenicity and transmissibility among the various subtypes. Molecular analyses of viral sequences allow estimating the rate of divergence among variants and the dynamic forces shaping the phylogenetic trees.

Acquired Immunodeficiency Syndrome↗
PubMed1992

[A strain of Aeromonas veronii isolated from a patient suspected of cholera].

Investigations were carried on a strain isolated from patient hospitalized in Poland. The patient returned from Odessa, a region with cholera epidemic. The strain was suspected to be Vibrio cholerae, but it did not agglutinate in V. cholerae 01 serum. The aim of this study was establishment of taxonomical classification of this strain, in order to demonstrate whether it is a representative of the non-cholera vibrio group (not agglutinating) or another representative of the family Vibrionaceae. The strain was resistant to bile salts in TCBS medium and demonstrated several properties from a borderline of two Vibrio and Aeromonas species. Its properties were similar to the group of recently described pathogenic vibrio, but it did not require higher concentrations of NaCl in the medium and was resistant to the vibriostatic factor 0/129. These properties were considered as decisive in differentiation of Vibrio and Aeromonas. The strain was finally classified as Aeromonas veronii. It is a first case in Poland of isolation of A. veronii from the feces of patient with cholera-like symptoms. As newly described pathogenic species of genus Vibrio and Aeromonas were not isolated in Poland, we present schemes which may serve for beginning of this type of diagnostic investigations.

Aeromonas↗
PubMed1991

[Systematics, differentiation, and detection of bacterial infections-- the family Mycobacteriaceae].

Comparative 16S rRNA sequencing allows to infer natural relationships among bacteria, to characterize and identify microorganisms at a molecular level and to develop DNA probes specific at any desired taxonomic level (e.g. family, genus, species). Probes targeted at ribosomal RNA are suitable for in situ hybridization of whole, intact bacterial cells as well as in polymerase-chain-reaction techniques for sensitive detection and identification of bacteria. Comparative 16S rRNA sequencing provided the basis for a systematic phylogenetic analysis of the genus Mycobacterium. Certain growth characteristics, i.e. thermotolerance and growth rate correspond to natural relationships among the mycobacteria. However, the phylogenetic relatedness within the slow-growing species did not reflect the Runyon classification of photochromogenic, scotochromogenic and nonphotochromogenic mycobacteria. The use of oligonucleotides targeted at highly or semi-conserved regions within the 16S rRNA molecule allows a universal procedure for amplification and rapid sequence determination of 16S rDNA-gene fragments from any virtually bacterial organism. This method of amplification of 16S rDNA-gene fragments was used to identify a novel, uncultured pathogen and opens new perspectives for other infectious diseases of unknown cause.

Base Sequence↗
PubMed1989

[Molecular markers and identification of Campylobacter pylori strains].

Campylobacter pylori was studied to define the classification of species and the typing of strains. The mol p. 100 G + C of 17 strains ranged from 34.1 to 37.5 (average value: 35.2; SD: 1.0). The strains are closely related (80 to 100 p. 100 DNA/DNA relatedness) and to the type strain NCTC 11367. The endonuclease restriction profiles were specific of strains. DNA analysis (REA) is a sensitive method in pathogenic and epidemiological studies.

Biomarkers↗
PubMed1987

Idiopathic cardiomyopathies. A review of pathologic studies and mechanisms of pathogenesis.

The purpose of this article is to provide a critical review of our current knowledge of the pathogenic mechanisms of human cardiomyopathy in the context of accepted morphologic findings (gross, microscopic, ultrastructural) and the clinical presentation of this disease. It is our intent to emphasize the numerous difficulties encountered in categorizing patients with cardiomyopathy to pursue investigations in the pathogenesis and origins of this puzzling cardiac condition. It is our belief that such difficulties stem primarily from the existing classification of cardiomyopathies, which is mostly empirical and somewhat vague. This is particularly true in regard to the dilated cardiomyopathies that probably encompass multiple entities grouped under the umbrella of cardiomegaly and dilation. The article's objective is to summarize clinical symptoms and signs, modalities of diagnostic investigations, and prognosis for each category of cardiomyopathy. However, the main purpose of this article is to present recent findings on the origins, possible autoimmune basis of the disease, and results of immunologic studies in patients with cardiomyopathy.

Antibody Formation↗
PubMed1979

[Surgical intervention in cold nodules of the thyroid gland (author's transl)].

In statistical analyses the rate of malignancy of solitary cold thyroid nodules is estimated between 3 to 50%. In our records the incidence of malignancy is 6,6%. Concerning the pathogenicity of these thyroid nodules no conclusions can be drawn which are only based on the results of such analyses. Each thyroid nodule has to be classified either according to its clinical and morphological characteristics or to its morphology alone. The condition for an optimal diagnosis and therapy is provided by the surgeon and pathologist being acquainted with the criteria for morphological classification or clinical data respectively.

Adenoma↗
PubMed1999

[Chlamydia pneumoniae in coronary plaques: Increased detection with acute coronary syndrome].

BACKGROUND AND OBJECTIVE: There is seroepidemiologic and experimental evidence for a link between Chlamydia (C.) pneumoniae and arteriosclerosis. However, the clinical importance and the pathogenic pathways implicated remain unclear. In the present study, we sought to evaluate the presence and the location of C. pneumoniae in coronary atheroma, as well as a potential prevalence with unstable versus stable angina. PATIENTS AND METHODS: Retrospectively, coronary plaque material of primary lesions from 51 consecutive patients (44 men, 7 women, mean age 59.6 +/- 9.4 years) was examined for the presence of C. pneumoniae by use of immuno-histochemistry and transmission electron microscopy. The findings associated with clinically acute coronary syndrome according to Braunwald's classification (n = 31) were compared to those with stable angina (n = 20) and regarded for potential relations to characteristic intimal features. RESULTS: Immunoreaction for C. pneumoniae was found in 32 of 51 (63%) coronary plaques. Signals (% prevalence of specific intimal features) were present with necrotic areas (40%), sparse cellularity (40%), neo-vascularization (29%), thrombi (20%), ruptured plaque areas (19%), and fields rich in foam cells and calcifications (13%). Intimal hyperplasia and inflammatory infiltrates showed no signals. As the central finding in this report, C. pneumoniae immunoreaction was more frequently (P < 0.001) found in 26 of 31 (84%) lesions associated with unstable angina or acute myocardial infarction, compared to 6 of 20 (30%) lesions with stable angina (P < 0.001). Intact vessels devoid of arteriosclerotic disease, such as mammarial arteries and saphenous veins, were without C. pneumoniae signals (negative controls). Ultrastructurally, chlamydial elementary bodies were found in foam cells and phagocytosing macrophages, also in fragmented extracellular matrix adjacent to apoptotic and necrotic intimal cells. CONCLUSIONS: Chlamydiae pneumoniae were detected in 32 of 51 (63%) coronary primary lesions of symptomatic patients. Most importantly, there was a highly significant prevalence of lesions associated with acute coronary syndrome. Predilection sites of C. pneumoniae were areas that revealed small healing activity and (or) propensity to plaque rupture. The present in situ findings indicate a pathogenic role of Chlamydiae pneumoniae in human (coronary) plaque rupture.

Aged↗
PubMed1991

Classification of coagulase-negative staphylococci isolated from bovine clinical and subclinical mastitis.

One hundred and forty eight strains of coagulase-negative staphylococci (CNS) from bovine clinical and subclinical mastitis were classified by conventional biochemical testing. Staphylococcus simulans was the most frequently isolated species. The distribution of CNS species in the two groups was similar regardless of whether the cow suffered from clinical or subclinical mastitis. There was no significant difference between the grades of severity of the clinical mastitis associated with the various CNS. The small difference in pathogenicity observed between species in this study, and the similarity of distribution in the various species of clinical and subclinical mastitis could indicate that the species per se is of minor importance in the development of mastitis.

Animals↗
PubMed2004

Genome sequence of the lignocellulose degrading fungus Phanerochaete chrysosporium strain RP78.

White rot fungi efficiently degrade lignin, a complex aromatic polymer in wood that is among the most abundant natural materials on earth. These fungi use extracellular oxidative enzymes that are also able to transform related aromatic compounds found in explosive contaminants, pesticides and toxic waste. We have sequenced the 30-million base-pair genome of Phanerochaete chrysosporium strain RP78 using a whole genome shotgun approach. The P. chrysosporium genome reveals an impressive array of genes encoding secreted oxidases, peroxidases and hydrolytic enzymes that cooperate in wood decay. Analysis of the genome data will enhance our understanding of lignocellulose degradation, a pivotal process in the global carbon cycle, and provide a framework for further development of bioprocesses for biomass utilization, organopollutant degradation and fiber bleaching. This genome provides a high quality draft sequence of a basidiomycete, a major fungal phylum that includes important plant and animal pathogens.

Base Composition↗
PubMed2002

[Identification and classification of beta-lactamases in clinical isolates of bacteria].

Emergence of bacterial resistance has rendered ineffective a number of previously valuable antibiotic treatments and now threatens the effectiveness of others. beta-Lactam resistance is no longer predominantly a hospital-treated problem; it has now become an important issue in community medicine. More than 100-beta-lactamases have been identified and classified according to their structure, substrate specificity, and whether they are chromosomal or plasmid-mediated. beta-Lactamase production is rare among Gram-positive pathogens, important exceptions being Staphylococcus aureus and Enterococcus faecalis. By contrast, many Gram-negative pathogens are beta-lactamase-positive; inducible and/or hyper-productive strains are particularly challenging in the clinical setting. Surveillance programs have shown that, in general, beta-lactam resistance is on the increase, and that the plasmid-mediated beta-lactamase have developed rapidly over past decade such as ESBLs and carbapenemases.

Gram-Negative Bacteria↗
PubMed1996

Microbiology of nontuberculosis mycobacteria.

Recognition of differences, particularly in color and other growth characteristics, between Mycobacterium tuberculosis and other related organisms has led to the identification of the nontuberculosis mycobacteria (NTM). The Runyon Classification, based largely on the presence (or absence) of pigment and rate of growth, was a convenient system for classifying these organisms. Subsequent biochemical analysis has facilitated more precise speciation. However, many of these tests are complex and time consuming and beyond the capacity of most laboratories other than reference centers. The need for accurate identification has become clear because of differences in pathogenicity and treatment between various species and even subspecies of NTM. The recent appearance of rapid diagnostic tests and highly specific genetic identification systems have created new opportunities and challenges with respect to the identification of NTM. This article provides a historic context for the microbiologic study of the organisms, describes key features of the most commonly encountered NTM, notes several important new technical innovations in this field, and considers common clinical issues in relation to the microbiology of NTM.

Bacterial Typing Techniques↗
PubMed1998

Two lineages of mannose-binding lectin-associated serine protease (MASP) in vertebrates.

Mannose-binding lectin-associated serine protease (MASP) is a newly identified member of the serine protease superfamily. MASP is involved in host defense against pathogens through a novel system of complement activation, designated the lectin pathway. To elucidate the origin of the lectin pathway and the molecular evolution of MASP, we cloned six MASP cDNAs from five vertebrate species going from mammal to cyclostome. An alignment of the amino acid sequences deduced from the cDNAs revealed the presence of two different lineages of the MASP gene. This classification was supported by the precise correlation with two types of exon organization for the protease domain. One of the two lineages is unique in that a single exon encodes the protease domain, unlike most other serine proteases. All members of this group, termed the AGY type, have an AGY codon at the active site serine. A phylogenetic tree suggests that the AGY type diverged from another lineage, termed the TCN type, before the emergence of primitive vertebrates. Furthermore, the presence of MASP or MASP-like sequences in most vertebrate species suggests that the lectin pathway functions extensively in vertebrates and that its origin is traced back to the invertebrate stage.

Amino Acid Sequence↗
PubMed1996

Detection of pathogenic and non-pathogenic bacteria by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

The proteins isolated from the whole cells of bacterial pathogens and related non-pathogenic simulants were analyzed directly, with minimal sample preparation by matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry. Inspection of mass spectrometric profiles obtained from direct MALDI-MS analysis of the protein extracts revealed specific biomarkers for individual bacterial cells. The observed biomarkers enabled us not only to detect pathogenic bacteria (Bacillus anthracis, Yersinia pestis and Brucella meliteusis), but also to distinguish them from the corresponding non-pathogenic species. By examining a series of strains of several Bacillus species (anthracis, thuringiensis, cereus and subtilis), it was possible to derive genus, species and strain-specific biomarkers from the measured molecular masses of the intact proteins. Additional series of biomarkers were obtained from direct mass spectrometric analysis of tryptic digests of the protein extracts. The application of this technique for rapid chemotaxonomic classification of microorganisms is demonstrated.

Bacteria↗