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At least 469 records · Page 26Linked to original sources
PubMed2006

Plasmid-mediated high-level gentamicin resistance among enteric bacteria isolated from pet turtles in Louisiana.

The sale of small turtles is banned by the Food and Drug Administration from the U.S. market due to concerns about their excretion of Salmonella spp. To produce a safe pet for the export market, the Louisiana pet turtle industry uses gentamicin sulfate baths (1,000 microg/ml) to eradicate Salmonella spp. from turtle eggs. In 1999, we analyzed bacterial samples recovered from turtle farms and found that strains of Salmonella enterica subsp. arizonae and other bacteria, such as Enterobacter cloacae, Citrobacter freundii, Pseudomonas aeruginosa, and Stenotrophomonas maltophilia, were resistant to high concentrations of gentamicin (>2,000 microg/ml) and to other aminoglycosides. The goal of this study was to identify the gene(s) which contributes to the high-level gentamicin resistance phenotype observed in bacteria from environmental samples with turtle farming activity, particularly the salmonellae, and to estimate the incidence of such genes in these bacteria. R plasmids from gentamicin-resistant strains were transferred by conjugation and transformation to naive Escherichia coli cells. Cloning and sequencing of the gentamicin resistance determinants on these plasmids revealed the presence of the aminoglycoside acetyltransferase genes aac(3)-IIa and aac(3)-VIa; the latter was present as a gene cassette of a class 1 integron. Multiplex PCR assays showed that every gentamicin-resistant isolate carried one of these acetyltransferase genes. Pulsed-field gel electrophoresis and restriction enzyme digestion analysis of R plasmids carrying these genes revealed different restriction profiles and sizes, indicating a dissemination of the gentamicin resistance genes through mobile molecular elements. The data presented highlight the need to develop an alternate method for the eradication of Salmonella spp. from turtle eggs.

Acetyltransferases↗
PubMed2005

Polyphasic characterization reveals that the human pathogen Mycobacterium peregrinum type II belongs to the bovine pathogen species Mycobacterium senegalense.

Mycobacterium peregrinum consists of two taxa: types I and II. We evaluated 43 clinical type II strains from throughout the United States. They were responsible for soft-tissue and bone infections, catheter-related infections, and possible pneumonitis. By carbohydrate utilization, they were indistinguishable from type I strains, being D-mannitol and trehalose positive. However, they had a distinct susceptibility pattern that included intermediate ciprofloxacin MICs but low clarithromycin and doxycycline MICs of < or =1 microg/ml. These features were also shared by reference isolates of Mycobacterium senegalense from African bovine cases of "farcy." By 16S rRNA gene sequencing, the type II isolates shared 100% sequence identity with M. senegalense. Partial sequencing of the type II hsp65 gene (441 bp) revealed four sequevars showing > or =98.4% identity with each other and > or =98.6% identity with the sequence of five bovine strains of M. senegalense. There was < or =97.1% identity with M. peregrinum type I isolates and other Mycobacterium fortuitum group species. Sequencing of additional gene targets including the 16S-23S rDNA internal transcribed spacer region and the rpoB gene (partial sequence) revealed a similar phylogenetic grouping. DNA-DNA hybridization showed 76 to 99% relatedness between the bovine and human strains. These studies demonstrate that type II isolates are not isolates of M. peregrinum but represent human strains of M. senegalense. This study is the first to demonstrate this species as a human pathogen. Representative human M. senegalense strains include ATCC 35755 and newly submitted strains ATCC BAA-849, ATCC BAA-850, and ATCC BAA-851.

Animals↗
PubMed2005

[Crohn's disease and infectious agents].

The author discusses possible etiological causes of Crohn's disease taking into consideration the undoubtedly significant impact of the constitution of the intestinal microbial flora. The author pays special attention to Yersinia; their presence in the intestines is believed to be the chief mechanism of subsequent immunity events resulting in the development of the disease. The author briefly discusses the possibilities of differential diagnosis and of treatment. He mentions the profitable cooperation of infectiousdiseases specialists and gastroenterologists in the diagnosis of diarrhoeal disorders.

Bacteria↗
PubMed1984

[Inflammatory brain diseases in clinical practice].

Over a period of twenty years all cases of inflammatory diseases treated in a neurological intensive-care unit were analysed in retrospective. For 90 cases of purulent bacterial meningitis, letality amounted to 30%. The need for agent-oriented, intensive early treatment is discussed. At a reduced incidence of tuberculosis, meningitis tuberculosa is generally neglected. In the majority of cases patients suffering from "encephalitic syndrome" make high demands on intensive-therapeutic concepts, including interdisciplinary cooperation, due to high complication-rates and lack of causal therapy. In 95 cases, letality also amounted to 30%.

Adolescent↗
PubMed1995

Periodontal disease in adult insulin-dependent diabetics.

The overall objective with the present investigations was to study the influence of insulin-dependent diabetes mellitus (IDDM) on periodontal conditions and to identify factors that may be predictors for severe periodontal disease in individuals with IDDM. Periodontal conditions were studied in two cross-sectional studies of adult, insulin-dependent diabetics and age-and sex-matched controls. In one study 72 diabetics with short-(SD) and 82 with long-duration (LD) diabetes and 77 controls participated. In the other study 83 LD diabetics and 99 controls took part. The portion of individuals exhibiting severe periodontal disease was larger in the diabetic group than in the control group. Advanced periodontal disease appeared in earlier ages (40-49 years) in the LD diabetics compared to the SD diabetics and controls. In fact, the 40-49-year-old LD diabetics had alveolar bone loss equal to the older controls (60-69 years). LD diabetics exhibited more severe periodontitis than SD diabetics. Some salivary factors were studied in 72 SD and 82 LD diabetics and 77 controls. LD and SD diabetics had a lower stimulated salivary secretion rate and an increased glucose content compared to the controls. The reduction in flow rate, however, was moderate, and all mean values were within the normal limits. The moderately increased glucose content did not result in higher mean numbers of Candida albicans, lactobacilli, and mutans streptococci. The subgingival bacterial species currently considered to be associated with periodontitis were studied in 30 LD diabetics and 34 controls. All these bacterial species were recovered in diabetics as well as controls. More LD diabetics than controls harboured Porphyromonas gingivalis. In the control group the periopathogens were recovered more often in deep periodontal pockets. In the LD group, however, these bacterial species were recovered as often in shallow as in deep periodontal pockets. The medical status of 39 matched pairs of LD diabetics was analysed. One in each pair had severe periodontal disease while the other had no/minor symptoms of periodontal disease. Biochemical analyses and clinical variables routinely used in monitoring diabetics failed to discriminate between diabetics with severe and minor periodontal disease. Diabetics with severe periodontal disease, however, showed a higher prevalence of renal disease and cardiovascular complications such as stroke, transient ischemic attacks, angina, myocardial infarct, heart failure, and claudicatio intermittens than diabetics with only minor periodontal disease. This indicates that closer cooperation between the diabetologist and the dentist is necessary in monitoring the diabetic patient.

Adult↗
PubMed1980

Hormonal interactions in mammalian collagenase regulation. Comparative studies in human skin and rat uterus.

The production of collagenase by human skin explants in culture is prevented by 10(-8) M dexamethasone, 5 . 10(-4) M dibutyryl cyclic AMP, or 2.5 . 10(-3) M theophylline. Decreases in collagenase activity are paralleled by reductions in the degradation of explant collagen during the culture period. Progesterone, which effectively inhibits collagenase production in rat uterine explant cultures, has no effect on human skin explants. The inhibition by cyclic AMP is nucleotide specific. When partially inhibitory concentrations of dexamethasone and dibutyryl cyclic AMP, or dexamethasone and theophylline, are added to culture medium together, the resultant inhibition is that predicted by additivity. Synergistic inhibition, as observed in rat uterus between progesterone and dibutyryl cyclic AMP, fails to occur. Dexamethasone inhibits the production of collagenase by cultured explants of rat uterus, with complete inhibition occurring at 10(-7) M steroid. Synergism between glucocorticoids and dibutyryl cyclic AMP or between dexamethasone and progesterone could not be demonstrated in the uterine culture system. These results suggest the existence of three regulatory systems for the control of collagenase production in mammalian tissues, and that cooperativity between systems may occur on a tissue-specific basis.

Animals↗
PubMed1998

Comparative and library epidemiological typing systems: outbreak investigations versus surveillance systems.

A number of high-resolution molecular typing systems have been developed in recent years. Their availability raises the new issues of selecting the method (s) best suited for a particular purpose and interpreting and communicating typing results. Most of the currently available methods are comparative only: they allow testing of a sample of isolates for delineation of those closely related from those markedly different in genomic backgrounds. This approach is adequate for outbreak investigation, allowing determination of clonal spread in a microenvironment and identification of the source of infection. Comparative methods with sufficient resolution for most pathogens include restriction fragment-length polymorphism (RFLP), pulsed-field gel electrophoresis (PFGE), and arbitrarily primed and randomly amplified polymorphic DNA-polymerase chain reaction (PCR) analysis. For surveillance systems, monitoring clonal spread and prevalence in populations over extended periods of time requires library typing systems. These must be standardized, must have a high throughput, and must use a uniform nomenclature. Promising or validated methods include serotyping, insertion sequence fingerprinting, ribotyping, PFGE, amplified fragment-length polymorphism (AFLP), infrequent-restriction-site amplification PCR, interrepetitive element PCR typing (rep-PCR) and PCR-RFLP of polymorphic loci. PCR methods generating arrays of size-specific amplicons (AFLP, rep-PCR) can be more reproducibly analyzed by using denaturing polyacrylamide gel or capillary electrophoresis with automated laser detection. Binary probe typing systems appear optimal and should be enhanced further through use of DNA chip technology. In these systems, amplification of polymorphic regions is followed by solid-phase hybridization with a reference panel of sequence-variant specific probes. The resulting binary type results allow determination of reproducible, numeric profiles. However, interpretation and nomenclature of typing results for large-scale surveillance purposes still require a better understanding of population structure and microevolution of most microbial pathogens.

Bacterial Infections↗
PubMed1988

Modifications of oxidative phosphorylations in mitochondria isolated from a mutant of Saccharomyces cerevisiae. Possible alterations of the phosphate transport.

Mutants of Saccharomyces cerevisiae were isolated which supported two unlinked nuclear mutations conferring thermosensitivity and cold sensitivity respectively, and a mitochondrial one conferring paromomycin sensitivity. Mitochondria isolated from such a mutant exhibited modifications of several phosphate-requiring functions: (a) kinetic parameters of the phosphate dependence of ATP synthesis were modified; (b) in the absence of phosphate the inner mitochondrial membrane exhibited a high proton leakage; (c) mutant mitochondria always exhibited a poor respiratory control and required tenfold more phosphate to reach a maximal state 3 of respiration; (d) phosphate transport, as measured by swelling experiments, was mersalyl-insensitive and, consequently, state 3 of the respiration and ATP synthesis remained less mersalyl-sensitive than in wild-type mitochondria. Analysis of the mitochondrial metabolism of diploid and segregant strains indicates that these modifications are related to the cryosensitive phenotype; however, at present, a cooperative effect of the mitochondrial mutation cannot be eliminated. It is proposed that the phosphate carrier itself or a regulatory element was modified.

Adenosine Triphosphate↗
PubMed2003

Alpha interferon augments cidofovir's antiviral and antiproliferative activities.

The antiviral and antiproliferative activities of alpha 2a interferon (IFN-alpha 2a) and cidofovir in human papillomavirus type 16 (HPV-16)-transformed keratinocytes were evaluated. The compounds in combination were more effective than comparable levels of either drug alone. Evaluation of effective drug ratios revealed a synergistic cooperation between IFN-alpha 2a and cidofovir in inhibiting the proliferation of HPV-infected cells.

Antiviral Agents↗
PubMed1995

Antibacterial activity of three dental liners.

PURPOSE: The purpose of the present study was to assess the antibacterial activity of the following three dental liners: Vitrebond (3M, St Paul, MN), Dycal (LD Caulk, Dentsply International, Milford, DE), and Life (Kerr, Romulus, MI). MATERIALS AND METHODS: The test was based on a modification of the agar diffusion test in which samples were placed on agar plates previously inoculated with Streptococcus mutans and were removed after predetermined time periods. The material's effect on bacterial growth was evaluated. RESULTS: Results show that Vitrebond has a strong antibacterial effect that was evident after 1 minute of direct contact with the inoculated bacteria. It was significantly more effective (P<.0001) than Dycal or Life. CONCLUSIONS: This method allows for the evaluation of the antibacterial effect of dental materials.

Analysis of Variance↗
PubMed1976

Automatic quantitative radiometric assay of bacterial metabolism.

In a two-compartment scintillation vial, suspensions of bacteria were cultured with 1 muCi of [U-14C] glucose and the released 14C02 was measured continuously, cumulatively, and automatically in a liquid-scintillation counter modified to maintain sample temperature at 37 degrees C. We could follow the metabolism of bacterial populations through their early phase of exponential growth with good precision. The data were obtained conveniently, with use of conventional reagents, glassware, and counting equipment. From analysis of the exponential portion of the curves for cumulative activity vs. time, we could measure cell replication rate precisely in units of time. The resulting values were demonstrably independent of some common experimental variables, including the number of bacteria in the inoculum and counting system sensitivity. Sensitivity of the bacteria to antibiotics was measured to within a few percent by noting the relative prolongation of replication time in the presence of those inhibitors. The digital data from the scintillation counter are susceptible to on- or off-line computer analysis, thus providing the prospect for a totally-automated analytical system. The method shows promise for the mechanized quantitative analysis of bacterial growth, and its inhibition.

Anti-Bacterial Agents↗
PubMedDate not supplied

The role of industry in the development of a product for control of mycoplasmal plant diseases.

A number of mycoplasmal or mycoplasma-like diseases of plants have been treated with an oxytetracycline-based product. Remission of symptoms has generally resulted, and in some instances the local use of this product under temporary governmental registrations has been approved. The use of oxytetracycline for control of many such diseases is not commercially feasible because the potential market is relatively small and the costs of development are relatively high. However, oxytetracycline products may be useful when a disease problem becomes sufficiently serious to arouse academic attention and agricultural or public concern. The commercial use of oxytetracycline hydrochloride for remission and prevention of lethal yellowing of coconut palm was begun in 1974. Use of this product for control of pear decline disease followed shortly thereafter. To date, joint participation and cooperation of the drug and agricultural industries have also resulted in the control of two important mycoplasma-like diseases of peach trees in the United States.

Biodegradation, Environmental↗
PubMed1984

Extracellular cysteine proteinase and collagenase activities as a consequence of tumor-host interaction in the rabbit V2 carcinoma.

Specimens of the rabbit V2 carcinoma were maintained in organ culture to study the secretion of proteinases. Elastase-like, chymotrypsin-like, plasminogen activator-like, cathepsin B-like and collagenase activities were assayed with sensitive fluorimetric techniques. Of these enzymes, the only activities that were secreted in considerable amounts in primary cultures of tumor tissue were collagenase and a cysteine proteinase resembling cathepsin B. Co-cultures of intraperitoneally grown tumor and normal subcutaneous tissue of the rabbit resulted in significantly higher production of the cysteine proteinase and collagenase compared to the sum of the activities of the separate tissues. Explants of subcutaneous tissue of tumor-bearing rabbits secreted significantly more cysteine proteinase and collagenase than explants from normal animals. Explants from normal subcutaneous tissue stimulated with tumor-conditioned culture medium secreted both enzymes in higher amounts compared to the controls. The cysteine proteinase was similar in some properties to rabbit liver cathepsin B, but the enzyme from the tumor-host system showed a remarkable stability to a moderately alkaline pH. We suggest that a diffusible factor, derived from the tumor or immigrated cells, promotes an increased synthesis and secretion of collagenase and cysteine proteinase in the host, and that both enzymes may play cooperative roles during invasion of the surrounding tissues by the V2 carcinoma.

Animals↗
PubMed1997

Epidemiologic analysis of Mycoplasma spp isolated from bulk-tank milk samples obtained from dairy herds that were members of a milk cooperative.

OBJECTIVE: To determine the prevalence of Mycoplasma spp in herds that were members of a milk cooperative. DESIGN: Epidemiologic study. SAMPLE POPULATION: 267 dairy herds that were members of a milk cooperative. PROCEDURE: Bulk-tank milk samples were collected monthly during a 6-year period from all dairies in the cooperative. Samples were submitted to the cooperative's laboratory for bacterial culture for Mycoplasma spp, using direct plating. Milk samples positive for Mycoplasma organisms were speciated. RESULTS: Prevalence of positive samples varied from 1.8 to 5.8% for all species of Mycoplasma and from 1.2 to 3.1% for Mycoplasma spp known to be mastitis pathogens. One mycoplasmal species was isolated initially on 99 of 198 (50.0%) dairies, but 68 of 198 (34.3%) dairies had 2 species isolated. Mycoplasma bovis, M californicum, and M bovigenitalium were consistently isolated, but M bovis (243/499; 48.6%) was the most commonly isolated species. Acholeplasma laidlawii was more prevalent in 1989 and 1995 than other years. Mycoplasma bovigenitalium and M californicum had a seasonal distribution. Less than 50 colonies per plate were isolated for most (317/500; 63.4%) bulk-tank samples. Of the milk samples with > 100 colonies/plate, Mycoplasma bovis was isolated most frequently (73/243; 30.0%). CLINICAL IMPLICATIONS: Distribution of Mycoplasma spp varied by year, number of colonies isolated per sample, season, and herd. Therefore, it may be necessary to routinely sample bulk-tank milk, and all isolates should be speciated. Culture results from milk cooperatives should be used with other monitoring information to determine the Mycoplasma status of herds.

Analysis of Variance↗