Kooperativer Bibliotheksverbund

Berlin Brandenburg

and
and

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • JSTOR Archival Journals  (83)
Type of Medium
Language
Year
  • 1
    Language: English
    In: The Journal of infectious diseases, 01 January 2010, Vol.201(1), pp.42-51
    Description: Repeated Chlamydia trachomatis infections are common among young sexually active women. The relative frequency of reinfection and antibiotic treatment failure is undefined. Adolescent women enrolled in a longitudinal cohort had behavioral and sexually transmitted infection assessments performed every 3 months, including amplification tests for C. trachomatis, ompA genotyping, and interviews and diary entries to document sex partner-specific coitus and event-specific condom use. Repeated infections were classified as reinfection or treatment failure by use of an algorithm. All infections for which treatment outcomes were known were used to estimate the effectiveness of antibiotic use. We observed 478 episodes of infection among 210 study participants; 176 women remained uninfected. The incidence rate was 34 episodes/100 woman-years. Of the women who were infected, 121 experienced 1 repeated infections, forming 268 episode pairs; 183 pairs had complete data available and were classified using the algorithm. Of the repeated infections, 84.2% were definite, probable, or possible reinfections; 13.7% were probable or possible treatment failures; and 2.2% persisted without documented treatment. For 318 evaluable infections, we estimated 92.2% effectiveness of antibiotic use. Most repeated chlamydial infections in this high-incidence cohort were reinfections, but repeated infections resulting from treatment failures occurred as well. Our results have implications for male screening and partner notification programs and suggest the need for improved antibiotic therapies.
    Keywords: Anti-Bacterial Agents -- Therapeutic Use ; Azithromycin -- Therapeutic Use ; Chlamydia Infections -- Drug Therapy
    ISSN: 00221899
    E-ISSN: 1537-6613
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Language: English
    In: The Journal of infectious diseases, 15 June 2011, Vol.203(12), pp.1859-65
    Description: Haemophilus ducreyi 35000HP contains a homolog of the CpxRA 2-component signal transduction system, which controls the cell envelope stress response system in other gram-negative bacteria and regulates some important H. ducreyi virulence factors. A H. ducreyi cpxR mutant was compared with its parent for virulence in the human challenge model of experimental chancroid. The pustule formation rate in 5 volunteers was 33% (95% confidence interval [CI], 1.3%-65.3%) at 15 parent sites and 40% (95% CI, 18.1%-61.9%) at 15 mutant sites (P = .35). Thus, the cpxR mutant was not attenuated for virulence. Inactivation of the H. ducreyi cpxR gene did not reduce the ability of this mutant to express certain proven virulence factors, including the DsrA serum resistance protein and the LspA2 protein, which inhibits phagocytosis. These results expand our understanding of the involvement of the CpxRA system in regulating virulence expression in H. ducreyi.
    Keywords: Bacterial Proteins -- Genetics ; Chancroid -- Microbiology ; Haemophilus Ducreyi -- Genetics
    ISSN: 00221899
    E-ISSN: 1537-6613
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Language: English
    In: The Journal of infectious diseases, November 2012, Vol.206(9), pp.1407-14
    Description: Haemophilus ducreyi encounters several classes of antimicrobial peptides (APs) in vivo and utilizes the sensitive-to-antimicrobial-peptides (Sap) transporter as one mechanism of AP resistance. A mutant lacking the periplasmic solute-binding component, SapA, was somewhat more sensitive to the cathelicidin LL-37 than the parent strain and was partially attenuated for virulence. The partial attenuation led us to question whether the transporter is fully abrogated in the sapA mutant. We generated a nonpolar sapBC mutant, which lacks both inner membrane permeases of the Sap transporter, and tested the mutant for virulence in human volunteers. In vitro, we compared LL-37 resistance phenotypes of the sapBC and sapA mutants. Unlike the sapA mutant, the sapBC mutant was fully attenuated for virulence in human volunteers. In vitro, the sapBC mutant exhibited significantly greater sensitivity than the sapA mutant to killing by LL-37. Similar to the sapA mutant, the sapBC mutant did not affect H. ducreyi's resistance to human defensins. Compared with the sapA mutant, the sapBC mutant exhibited greater attenuation in vivo, which directly correlated with increased sensitivity to LL-37 in vitro. These results strongly suggest that the SapBC channel retains activity when SapA is removed.
    Keywords: Drug Resistance, Bacterial ; Antimicrobial Cationic Peptides -- Pharmacology ; Haemophilus Ducreyi -- Enzymology ; Membrane Transport Proteins -- Metabolism ; Virulence Factors -- Metabolism
    ISSN: 00221899
    E-ISSN: 1537-6613
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Language: English
    In: The Journal of infectious diseases, 15 June 2010, Vol.201(12), pp.1839-48
    Description: Haemophilus ducreyi causes chancroid, a genital ulcer disease. Among human volunteers, the majority of experimentally infected individuals fail to clear the infection and form pustules. Here, we investigated the role played by CD4(+)FOXP3(+) regulatory T (T(reg)) cells in the formation of pustules. In pustules, there was a significant enrichment of CD4(+)FOXP3(+) T cells, compared with that in peripheral blood. The majority of lesional FOXP3(+) T cells were CD4(+), CD25(+), CD127(lo/-), and CTLA-4(+). FOXP3(+) T cells were found throughout pustules but were most abundant at their base. Significantly fewer lesional CD4(+)FOXP3(+) T cells expressed interferon gamma, compared with lesional CD4(+)FOXP3(-) effector T cells. Depletion of CD4(+)CD25(+) T cells from the peripheral blood of infected and uninfected volunteers significantly enhanced proliferation of H. ducreyi-reactive CD4(+) T cells. Our results indicate that the population of CD4(+)CD25(+)CD127(lo/-)FOXP3(+) T(reg) cells are expanded at H. ducreyi-infected sites and that these cells may play a role in suppressing the host immune response to the bacterium.
    Keywords: Immune Tolerance ; Cd4-Positive T-Lymphocytes -- Immunology ; Forkhead Transcription Factors -- Analysis ; Haemophilus Infections -- Immunology ; Haemophilus Ducreyi -- Immunology ; T-Lymphocytes, Regulatory -- Immunology
    ISSN: 00221899
    E-ISSN: 1537-6613
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    In: Journal of the Royal Statistical Society: Series A (Statistics in Society), October 2011, Vol.174(4), pp.975-989
    Description: Bacterium causes genital chlamydia infection. Yet little is known about the efficiency of transmission of this organism. Ethical constraint against exposing healthy subjects to infected partners precludes the possibility of quantifying the risk of transmission through controlled experiments. This research proposes an alternative strategy that relies on observational data. Specifically, we present a stochastic model that treats longitudinally observed states of infection in a group of young women as a Markov process. The model proposed explicitly accommodates the parameters of transmission, including per‐encounter sexually transmitted infection acquisition risks, with and without condom protection, and the probability of antibiotic treatment failure. The male‐to‐female transmission probability of is then estimated by combining the per‐encounter disease acquisition risk and the organism's prevalence in the male partner population. The model proposed is fitted in a Bayesian computational framework.
    Keywords: Bacterial Infection ; Binary Outcome ; Longitudinal Study ; Markov Chain Monte Carlo Methods ; Markov Model ; Observational Data ; Transmission Probability
    ISSN: 0964-1998
    E-ISSN: 1467-985X
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    In: Perspectives on Sexual and Reproductive Health, March 2010, Vol.42(1), pp.43-48
    Description: CONTEXT: Adolescent pregnancy prevention is difficult because adolescent sex is intermittent. Understanding why sexually experienced adolescents have sex after a period of abstinence will help clinicians to tailor counseling. METHODS: For up to 4.5 years between 1999 and 2006, a sample of 354 adolescent women recruited at urban primary care clinics were interviewed and tested for STDs every three months, and were asked to complete three months of daily diaries twice a year. Survival analyses were used to estimate associations between intrapersonal, relationship and STD‐related characteristics and the risk of ending an abstinence period with sex. RESULTS: Participants reported 9,236 abstinence periods, which averaged 31 days. The risk that an abstinence period ended with sex increased steeply for periods of fewer than 17 days (short), rose less steeply for 17–39‐day (intermediate) periods and was fairly steady for longer periods. For short periods, the risk increased with age, sexual interest, positive mood, partner support, relationship quality and history of STD diagnosis more than three months ago (hazard ratios, 1.02–1.2); it decreased as negative mood increased (0.98) and was reduced among adolescents with a recent STD diagnosis (0.9). For intermediate periods, the association with a recent STD diagnosis became positive (1.4). For long periods, sex was associated only with age, sexual interest and relationship quality. CONCLUSIONS: To provide targeted and timely sexual health counseling, clinicians may want to ask adolescents not only whether they are sexually active but also when they last had sex.
    Keywords: Sexual Abstinence -- Research ; Teenage Sexual Behavior -- Research ; Sexual Intercourse -- Research;
    ISSN: 1538-6341
    E-ISSN: 1931-2393
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Language: English
    In: The Journal of infectious diseases, 01 June 2009, Vol.199(11), pp.1671-9
    Description: Haemophilus ducreyi causes chancroid, which facilitates transmission of human immunodeficiency virus type 1. To better understand the biology of H. ducreyi, we developed a human inoculation model. In the present article, we describe clinical outcomes for 267 volunteers who were infected with H. ducreyi. There was a relationship between papule formation and estimated delivered dose. The outcome (either pustule formation or resolution) of infected sites for a given subject was not independent; the most important determinants of pustule formation were sex and host effects. When 41 subjects were infected a second time, their outcomes segregated toward their initial outcome, confirming the host effect. Subjects with pustules developed local symptoms that required withdrawal from the study after a mean of 8.6 days. There were 191 volunteers who had tissue biopsy performed, 173 of whom were available for follow-up analysis; 28 (16.2%) of these developed hypertrophic scars, but the model was otherwise safe. Mutant-parent trials confirmed key features in H. ducreyi pathogenesis, and the model has provided an opportunity to study differential human susceptibility to a bacterial infection.
    Keywords: Chancroid -- Microbiology ; Haemophilus Ducreyi -- Pathogenicity
    ISSN: 0022-1899
    E-ISSN: 15376613
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Language: English
    In: The Journal of infectious diseases, 15 August 2009, Vol.200(4), pp.590-8
    Description: The role of natural killer (NK) cells in the host response to Haemophilus ducreyi infection is unclear. In pustules obtained from infected human volunteers, there was an enrichment of CD56bright NK cells bearing the activation markers CD69 and HLA-DR, compared with peripheral blood. To study the mechanism by which H. ducreyi activated NK cells, we used peripheral blood mononuclear cells from uninfected volunteers. H. ducreyi activated NK cells only in the presence of antigen-presenting cells. H. ducreyi-infected monocytes and monocyte-derived macrophages activated NK cells in a contact- and interleukin-18 (IL-18)-dependent manner, whereas monocyte-derived dendritic cells induced NK activation through soluble IL-12. More lesional NK cells than peripheral blood NK cells produced IFN-gamma in response to IL-12 and IL-18. We conclude that NK cells are recruited to experimental lesions and likely are activated by infected macrophages and dendritic cells. IFN-gamma produced by lesional NK cells may facilitate phagocytosis of H. ducreyi.
    Keywords: Haemophilus Ducreyi ; Chancroid -- Immunology ; Killer Cells, Natural -- Physiology ; Lymphocyte Activation -- Physiology
    ISSN: 0022-1899
    E-ISSN: 15376613
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Language: English
    In: The Journal of infectious diseases, 01 March 2009, Vol.199(5), pp.684-92
    Description: A gene expression study of Haemophilus ducreyi identified the hypothetical lipoprotein HD0192, renamed here "fibrinogen binder A" (FgbA), as being preferentially expressed in vivo. To test the role played by fgbA in virulence, an isogenic fgbA mutant (35000HPfgbA) was constructed using H. ducreyi 35000HP, and 6 volunteers were experimentally infected with 35000HP or 35000HPfgbA. The overall pustule-formation rate was 61.1% at parent sites and 22.2% at mutant sites (P = .019). Papules were significantly smaller at mutant sites than at parent sites (13.3 vs. 37.9 mm(2); P = .002) 24 h after inoculation. Thus, fgbA contributed significantly to the virulence of H. ducreyi in humans. In vitro experiments demonstrated that fgbA encodes a fibrinogen-binding protein; no other fibrinogen-binding proteins were identified in 35000HP. fgbA was conserved among clinical isolates of both class I and II H. ducreyi strains, supporting the finding that fgbA is important for H. ducreyi infection.
    Keywords: Bacterial Proteins -- Metabolism ; Chancroid -- Microbiology ; Fibrinogen -- Metabolism ; Haemophilus Ducreyi -- Genetics ; Lipoproteins -- Metabolism
    ISSN: 0022-1899
    E-ISSN: 15376613
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Language: English
    In: The Journal of infectious diseases, 01 August 2009, Vol.200(3), pp.409-16
    Description: Haemophilus ducreyi 35000HP contains a homologue of the luxS gene, which encodes an enzyme that synthesizes autoinducer 2 (AI-2) in other gram-negative bacteria. H. ducreyi 35000HP produced AI-2 that functioned in a Vibrio harveyi-based reporter system. A H. ducreyi luxS mutant was constructed by insertional inactivation of the luxS gene and lost the ability to produce AI-2. Provision of the H. ducreyi luxS gene in trans partially restored AI-2 production by the mutant. The luxS mutant was compared with its parent for virulence in the human challenge model of experimental chancroid. The pustule-formation rate in 5 volunteers was 93.3% (95% confidence interval, 81.7%-99.9%) at 15 parent sites and 60.0% (95% confidence interval, 48.3%-71.7%) at 15 mutant sites (1-tailed P 〈 .001). Thus, the luxS mutant was partially attenuated for virulence. This is the first report of AI-2 production contributing to the pathogenesis of a genital ulcer disease.
    Keywords: Bacterial Proteins -- Metabolism ; Carbon-Sulfur Lyases -- Metabolism ; Chancroid -- Microbiology ; Haemophilus Ducreyi -- Genetics
    ISSN: 0022-1899
    E-ISSN: 15376613
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. Further information can be found on the KOBV privacy pages