How to Identify Exposed Women Who Are Infected with Neisseria gonorrhoeae.

Treatment trials of antibiotics for Neisseria gonorrhoeae infections frequently enroll primarily men with urethritis, as the diagnosis of acute gonococcal infection in men with urethritis is easily made by Gram stain of the urethral exudate, followed by confirmatory culture or nucleic acid amplification tests (NAATs). Enrolling women in treatment trials is of great importance, but N. gonorrhoeae cervical infections cause nonspecific symptoms. This makes it difficult to conduct interventional trials, as large numbers of women with nonspecific symptoms need to be screened for infection. Gram stain of cervical secretions has a strikingly low sensitivity, and culture and/or NAAT results are not available at the time of screening. This necessitates recall and delayed treatment of infected women who may not return and who may spread the infection during the interval. In this chapter we present an algorithm, derived from a comparison of women who did, or did not, become infected during exposure, which identifies those women who are highly likely to be infected before culture and/or NAAT results are available. The algorithm provides an efficient way to conduct interventional trials in women without the problem of recall and delayed treatment

Inhibition of rhythmic neural spiking by noise: the occurrence of a minimum in activity with increasing noise

The effects of noise on neuronal dynamical systems are of much current interest. Here, we investigate noise-induced changes in the rhythmic firing activity of single Hodgkin–Huxley neurons. With additive input current, there is, in the absence of noise, a critical mean value µ = µc above which sustained periodic firing occurs. With initial conditions as resting values, for a range of values of the mean µ near the critical value, we have found that the firing rate is greatly reduced by noise, even of quite small amplitudes. Furthermore, the firing rate may undergo a pronounced minimum as the noise increases. This behavior has the opposite character to stochastic resonance and coherence resonance. We found that these phenomena occurred even when the initial conditions were chosen randomly or when the noise was switched on at a random time, indicating the robustness of the results. We also examined the effects of conductance-based noise on Hodgkin–Huxley neurons and obtained similar results, leading to the conclusion that the phenomena occur across a wide range of neuronal dynamical systems. Further, these phenomena will occur in diverse applications where a stable limit cycle coexists with a stable focus

The clinical diagnosis of pelvic inflammatory disease – reuse of electronic medical record data from 189 patients visiting a Swedish university hospital emergency department

BACKGROUND: The pelvic inflammatory disease (PID) diagnosis is mostly based on clinical findings. However, few studies have examined the clinical basis for the diagnostics of PID, which was the aim of this study. METHODS: A retrospective study was performed of 189 out-patients diagnosed as having PID at the obstetric and gynecological emergency department of a Swedish university hospital. Data on symptoms, signs, pelvic examination and laboratory tests were extracted from the electronic medical records in comparison with the diagnostic criteria of the PID Guideline of the US Center of Disease Control from 2002 (CDC 2002 Guidelines). RESULTS: Eight symptoms in varying combinations were associated with the PID diagnosis. Most of them are mentioned in the CDC 2002 Guidelines. Detected rates of C. Trachomatis (CT) and N. Gonorrhoeae (NG) were 5% and 0%, respectively, among the tested patients (CT = 52% and NG = 12%). The C-reactive protein was normal in the majority of tested patients. CONCLUSION: The clinical basis for the diagnostics of PID was largely in accordance with the criteria in the CDC 2002 Guidelines. The limited number of CT tests performed is somewhat disappointing, considering the fact that effective disease prevention includes widespread CT screening. Further studies in different settings are needed in order to analyze how the testing rate for CT can be improved in clinical praxis

Subclinical iron deficiency is a strong predictor of bacterial vaginosis in early pregnancy

BACKGROUND: Bacterial vaginosis (BV) is the single most common vaginal infection in women of childbearing age and associated with a sizeable infectious disease burden among both non-pregnant and pregnant women, including a significantly elevated risk of adverse pregnancy outcome. Overall, little progress has been made in identifying causal factors involved in BV acquisition and persistence. We sought to evaluate maternal iron status in early pregnancy as a putative risk factor for BV, considering that micronutrients, and iron deficiency in particular, affect the host response against bacterial colonization, even in the setting of mild micronutrient deficiencies. METHODS: In a nested case-control study, we compared maternal iron status at entry to prenatal care (mean gestational age 9.2 ± 2.6 weeks) between eighty women with healthy vaginal microflora and eighteen women with vaginosis-like microflora. Vaginal microflora status was assessed by assigning a modified Nugent score to a Gram-stained vaginal smear. Maternal iron status was assayed by an array of conventional erythrocyte and serum indicators for iron status assessment, but also by more sensitive and more specific indicators of iron deficiency, including soluble transferrin receptors (sTfR) as an accurate measure of cellular and tissue iron deficiency and the iron deficiency log(10)[sTfR/ferritin] index as the presently most accurate measure of body storage iron available. RESULTS: We found no statistically significant correlation between vaginal microflora status and routinely assessed iron parameters. In contrast, a highly significant difference between the healthy and vaginosis-like microflora groups of women was shown in mean values of sTfR concentrations (1.15 ± 0.30 mg/L versus 1.37 ± 0.38 mg/L, p = 0.008) and in mean iron deficiency log(10)[sTfR/ferritin] index values (1.57 ± 0.30 versus 1.08 ± 0.56, p = 0.003), indicating a strong association between iron deficiency and vaginosis-like microflora. An sTfR concentration >1.45 mg/L was associated with a 3-fold increased risk (95%CI: 1.4–6.7) of vaginosis-like microflora and after controlling for maternal age, gestational length, body mass, parity, and smoking habits with an adjusted odds ratio of 4.5 (95%CI: 1.4–14.2). CONCLUSION: We conclude that subclinical iron deficiency, presumably resulting from inadequate preconceptional iron supplies, is strongly and independently associated with vaginosis-like microflora during early pregnancy

Improving STD testing behavior among high-risk young adults by offering STD testing at a vocational school

<p>Abstract</p> <p>Background</p> <p>Chlamydia trachomatis infection (CT) is the most prevalent bacterial STD. Sexually active adolescents and young adults are the main risk group for CT. However, STD testing rates in this group are low since exposed individuals may not feel at risk, owing-at least in part-to the infection's largely asymptomatic nature. Designing new testing environments that are more appealing to young people who are most at risk of acquiring chlamydia can be an important strategy to improve overall testing rates. Here we evaluate the effect of a school-based sexual health program conducted among vocational school students, aiming to obtain better access for counseling and enhance students' STD testing behavior.</p> <p>Methods</p> <p>Adolescents (median age 19 years) attending a large vocational school were provided with sexual health education. Students filled in a questionnaire measuring CT risk and were offered STD testing. Using univariate and multivariate analysis, we assessed differences between men and women in STD-related risk behavior, sexual problems, CT testing behavior and determinants of CT testing behavior.</p> <p>Results</p> <p>Of 345 participants, 70% were female. Of the 287 sexually active students, 75% were at high risk for CT; one third of women reported sexual problems. Of sexually active participants, 61% provided a self-administered specimen for STD testing. Independent determinants for testing included STD related symptoms and no condom use. All CT diagnoses were in the high-CT-risk group. In the high-risk group, STD testing showed an increased uptake, from 27% (previous self-reported test) to 65% (current test). CT prevalence was 5.7%.</p> <p>Conclusions</p> <p>Vocational school students are a target population for versatile sexual health prevention. When provided with CT testing facilities and education, self selection mechanisms seemed to increase CT testing rate dramatically in this high-CT-risk population expressing sexual problems. Considering the relative ease of testing and treating large numbers of young adults, offering tests at a vocational school is feasible in reaching adolescents for STD screening. Although cost-effectiveness remains an issue counseling is effective in increasing test rates.</p

Incentive payments to general practitioners aimed at increasing opportunistic testing of young women for chlamydia: a pilot cluster randomised controlled trial

<p>Abstract</p> <p>Background</p> <p>Financial incentives have been used for many years internationally to improve quality of care in general practice. The aim of this pilot study was to determine if offering general practitioners (GP) a small incentive payment per test would increase chlamydia testing in women aged 16 to 24 years, attending general practice.</p> <p>Methods</p> <p>General practice clinics (n = 12) across Victoria, Australia, were cluster randomized to receive either a $AUD5 payment per chlamydia test or no payment for testing 16 to 24 year old women for chlamydia. Data were collected on the number of chlamydia tests and patient consultations undertaken by each GP over two time periods: 12 month pre-trial and 6 month trial period. The impact of the intervention was assessed using a mixed effects logistic regression model, accommodating for clustering at GP level.</p> <p>Results</p> <p>Testing increased from 6.2% (95% CI: 4.2, 8.4) to 8.8% (95% CI: 4.8, 13.0) (p = 0.1) in the control group and from 11.5% (95% CI: 4.6, 18.5) to 13.4% (95% CI: 9.5, 17.5) (p = 0.4) in the intervention group. Overall, the intervention did not result in a significant increase in chlamydia testing in general practice. The odds ratio for an increase in testing in the intervention group compared to the control group was 0.9 (95% CI: 0.6, 1.2). Major barriers to increased chlamydia testing reported by GPs included a lack of time, difficulty in remembering to offer testing and a lack of patient awareness around testing.</p> <p>Conclusions</p> <p>A small financial incentive alone did not increase chlamydia testing among young women attending general practice. It is possible small incentive payments in conjunction with reminder and feedback systems may be effective, as may higher financial incentive payments. Further research is required to determine if financial incentives can increase testing in Australian general practice, the type and level of financial scheme required and whether incentives needs to be part of a multi-faceted package.</p> <p>Trial Registration</p> <p>Australian New Zealand Clinical Trial Registry ACTRN12608000499381.</p

Chlamydia trachomatis infection during pregnancy associated with preterm delivery: a population-based prospective cohort study

Chlamydia trachomatis infection is the most prevalent bacterial sexually transmitted infection and may influence pregnancy outcome. This study was conducted to assess the effect of chlamydial infection during pregnancy on premature delivery and birthweight. Pregnant women attending a participating midwifery practice or antenatal clinic between February 2003 and January 2005 were eligible for the study. From 4,055 women self-administered questionnaires and urine samples, tested by PCR, were analysed for C. trachomatis infection. Pregnancy outcomes were obtained from midwives and hospital registries. Gestational ages and birthweights were analysed for 3,913 newborns. The C. trachomatis prevalence was 3.9%, but varied by age and socio-economic background. Chlamydial infection was, after adjustment for potential confounders, associated with preterm delivery before 32 weeks (OR 4.35 [95% CI 1.3, 15.2]) and 35 weeks gestation (OR 2.66 [95% CI 1.1, 6.5]), but not with low birthweight. Of all deliveries before 32 weeks and 35 weeks gestation 14.9% [95% CI 4.5, 39.5] and 7.4% [95% CI 2.5, 20.1] was attributable to C. trachomatis infection. Chlamydia trachomatis infection contributes significantly to early premature delivery and should be considered a public health problem, especially in young women and others at increased risk of C. trachomatis infection

How Noisy Adaptation of Neurons Shapes Interspike Interval Histograms and Correlations

Channel noise is the dominant intrinsic noise source of neurons causing variability in the timing of action potentials and interspike intervals (ISI). Slow adaptation currents are observed in many cells and strongly shape response properties of neurons. These currents are mediated by finite populations of ionic channels and may thus carry a substantial noise component. Here we study the effect of such adaptation noise on the ISI statistics of an integrate-and-fire model neuron by means of analytical techniques and extensive numerical simulations. We contrast this stochastic adaptation with the commonly studied case of a fast fluctuating current noise and a deterministic adaptation current (corresponding to an infinite population of adaptation channels). We derive analytical approximations for the ISI density and ISI serial correlation coefficient for both cases. For fast fluctuations and deterministic adaptation, the ISI density is well approximated by an inverse Gaussian (IG) and the ISI correlations are negative. In marked contrast, for stochastic adaptation, the density is more peaked and has a heavier tail than an IG density and the serial correlations are positive. A numerical study of the mixed case where both fast fluctuations and adaptation channel noise are present reveals a smooth transition between the analytically tractable limiting cases. Our conclusions are furthermore supported by numerical simulations of a biophysically more realistic Hodgkin-Huxley type model. Our results could be used to infer the dominant source of noise in neurons from their ISI statistics

What Is Stochastic Resonance? Definitions, Misconceptions, Debates, and Its Relevance to Biology

Stochastic resonance is said to be observed when increases in levels of unpredictable fluctuations—e.g., random noise—cause an increase in a metric of the quality of signal transmission or detection performance, rather than a decrease. This counterintuitive effect relies on system nonlinearities and on some parameter ranges being “suboptimal”. Stochastic resonance has been observed, quantified, and described in a plethora of physical and biological systems, including neurons. Being a topic of widespread multidisciplinary interest, the definition of stochastic resonance has evolved significantly over the last decade or so, leading to a number of debates, misunderstandings, and controversies. Perhaps the most important debate is whether the brain has evolved to utilize random noise in vivo, as part of the “neural code”. Surprisingly, this debate has been for the most part ignored by neuroscientists, despite much indirect evidence of a positive role for noise in the brain. We explore some of the reasons for this and argue why it would be more surprising if the brain did not exploit randomness provided by noise—via stochastic resonance or otherwise—than if it did. We also challenge neuroscientists and biologists, both computational and experimental, to embrace a very broad definition of stochastic resonance in terms of signal-processing “noise benefits”, and to devise experiments aimed at verifying that random variability can play a functional role in the brain, nervous system, or other areas of biology