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Background Sexual health (SH) services increasingly need to prioritise those at greatest risk of sexually transmitted infections (STIs). We used SH surveillance data to develop algorithms to triage individuals attending SH services within two high-risk populations: men who have sex with men (MSM) and young people (YP). Methods Separate multivariable logistic regression models for MSM and YP were developed using surveillance data on demographics, recent sexual history, prior STI diagnoses and drug/alcohol use from five clinics in 2015–2016 to identify factors associated with new STI diagnoses. The models were prospectively applied in one SH clinic in May 2017 as an external validation. Findings 9530 YP and 1448 MSM SH episodes informed model development. For YP, factors associated with new STI diagnosis (overall prevalence: 10.6%) were being of black or mixed white/black ethnicity; history of chlamydia diagnosis (previous year); and multiple partners/new partner (previous 3-months). The YPs model had reasonable performance (c-statistic: 0.703), but poor discrimination when externally validated (c-statistic: 0.539). For MSM, being of South Asian ethnicity; being born in Europe (excluding the UK); and condomless anal sex or drug use (both in previous 3-months) were associated with STI diagnosis (overall prevalence: 22.0%). The MSM model had a c-statistic of 0.676, reducing to 0.579 on validation. Interpretation SH surveillance data, including limited behavioural data, enabled triage algorithms to be developed, but its implementation may be problematic due to poor external performance. This approach may be more suitable to self-triage, including online, ensuring patients are directed towards appropriate services. Funding NIHR HTA programme (12/191/05)., Highlights • We report the development and validation of an algorithm predicting STI diagnosis among MSM and young people in England • Inclusion of sexual behaviour data, feasibly collected in clinical settings, was crucial to achieve reasonable model performance • External validation highlighted key limitations with automated triage based on predictive algorithms in sexual health settings

This paper presents a composite model in which two simulation approaches, discrete-event simulation (DES) and system dynamics (SD), are used together to address a major healthcare problem, the sexually transmitted infection Chlamydia. The paper continues an on-going discussion in the literature about the potential benefits of linking DES and SD. Previous researchers have argued that DES and SD are complementary approaches and many real-world problems would benefit from combining both methods. In this paper, a DES model of the hospital outpatient clinic which treats Chlamydia patients is combined with an SD model of the infection process in the community. These two models were developed in commercial software and linked in an automated fashion via an Excel interface. To our knowledge this is the first time such a composite model has been used in a healthcare setting. The model shows how the prevalence of Chlamydia at a community level affects (and is affected by) operational level decisions made in the hospital outpatient department. We discuss the additional benefits provided by the composite model over and above the benefits gained from the two individual models.

Background Economic evaluations of chlamydia screening programmes do not consistently show that widespread chlamydia screening is cost-effective, which shows uncertainty in some of the assumptions incorporated into the models used. We explored differences in cost estimates used in published cost-effectiveness analyses. Methods Studies were identified from a systematic review of cost-effectiveness analyses of chlamydia screening commissioned by the European Centre for Disease Prevention and Control (2014). We included studies from developed countries that took a national health service or statutory health insurance system perspective for comparison with the English setting (n=14; England, Scotland, the Netherlands, Sweden, Ireland, Denmark, Canada, and Australia). Management costs for seven major sequelae of chlamydia infection (pelvic inflammatory disease, ectopic pregnancy, tubal factor infertility, chronic pelvic pain, epididymitis, neonatal conjunctivitis, and neonatal pneumonia) were extracted from each paper. We adjusted costs to 2013–14 pounds sterling using the Hospital & Community Health Services index and historical Bank of England foreign currency exchange rates. We assessed the effect of considering different sequelae, management costs, or both on the estimated cost-effectiveness of chlamydia screening by applying unit costs of sequelae included in each paper to one set of literature-derived progression probabilities to estimate an overall cost of sequelae per chlamydia infection. Findings Only half of the studies included all seven major chlamydia sequelae. Papers commonly referred to one previously published source that mostly included older estimates (>10 years old). Sequelae management costs per case ranged from £171 to £3635 (pelvic inflammatory disease), £953 to £3615 (ectopic pregnancy), £546 to £6752 (tubal factor infertility), £159 to £3341 (chronic pelvic pain), £22 to £1008 (epididymitis), £11 to £1459 (neonatal conjunctivitis), and £433 to £3992 (neonatal pneumonia). Total cost of sequelae per case of chlamydia using a standard set of progression probabilities ranged from £37 to £412. Interpretation The large disparities in estimated unit costs of chlamydia sequelae considered in existing cost-effectiveness analyses can be attributed to different assumptions about disease management pathways and costs from different country perspectives. Therefore, updated cost-estimates for chlamydia sequelae specific to the English setting are needed to inform future economic evaluations of chlamydia control programmes in England. Funding None.

Previous studies have tended to relate Chlamydia pneumoniae (Cpn) infection to atherosclerosis. However, while serological studies have mostly reinforced this hypothesis, inconsistent and even contradictory findings have been reported in various researches. Recent papers have pointed to the significance of Cpn in atherosclerotic lesions, which are regarded as the initiator and cause of chronic inflammation. This bacterium develops atherosclerosis by phenotypic changes in vascular smooth muscle cells, dysregulation of endothelin-1 in the vascular wall, and releasing pro-inflammatory cytokines from Toll-like receptor-2 (TLR2). Furthermore, Cpn infection, particularly under hyperlipidemic conditions, enhances monocyte adhesion to endothelium; changes the physiology of the host, e.g., cholesterol homeostasis; and activates the Low-density lipoprotein (LDL) receptor, which is the initial step in atherogenesis. On the other hand, it has been reported that Cpn, even without the immune system of the host, has the ability to stimulate arterial thickening. Moreover, there is evidence that Cpn can increase the impact of the classical risk factors such as hyperlipidemia, pro-inflammatory cytokines, and smoking for atherosclerosis. Furthermore, animal studies have shown that Cpn infection can induce atherosclerotic, which alongside hyperlipidemia is a co-risk factor for cardiovascular disease. Although the exact link between Cpn and atherosclerosis has not been determined yet, previous studies have reported possible mechanisms of pathogenesis for this bacterium. Accordingly, investigating the exact role of this infection in causing atherosclerosis may be helpful in controlling the disease.

In this paper, we have considered a dynamical model of Chlamydia disease with varying total population size, saturation incidence rate and discrete time delay to become infectious. It is assumed that there is a time lag ( τ ) to account for the fact that an individual infected with bacterium Chlamydia trachomatis is not infectious until after some time after exposure. The probability that an individual remains in the latency period (exposed class) at least t time units before becoming infectious is given by a step function with value 1 for 0 ⩽ t τ and value zero for t > τ . The probability that an individual in the latency period has survived is given by e - μ τ , where μ denotes the natural mortality rate in all epidemiological classes. Pulse vaccination is an effective and important strategy for the elimination of infectious diseases and so we have analyzed this model with pulse vaccination. We have defined two positive numbers R 1 and R 2 . It is proved that there exists an infection-free periodic solution which is globally attractive if R 1 1 and the disease is permanent if R 2 > 1 . Our analytical findings are illustrated through computer simulation using MATLAB, which show the reliability of our model from the epidemiological point of view.

Rapid advancements in the genetic manipulation of obligate intracellular bacterial pathogens have been made over the past two years. In this paper we attempt to summarize the work published since 2011 that documents these exciting accomplishments. Although each genus comprising this diverse group of pathogens poses unique problems, requiring modifications of established techniques and the introduction of new tools, all appear amenable to genetic analysis. Significantly, the field is moving forward from a focus on the identification and development of genetic techniques to their application in addressing crucial questions related to mechanisms of bacterial pathogenicity and the requirements of obligate intracellular growth.

We read with great interest the paper by Chen et al. [(1)][1] deciphering the complex interplay between innate immunity, Chlamydia pneumoniae infection and dyslipidemia in atherogenesis. The authors conclude that both Chlamydia pneumoniae infection and dyslipidemia-induced metabolic stress use the

Background The potential role of genitourinary infection in the etiology of prostate cancer (CaP) has been extensively investigated for 30 years. Two basic approaches have been used: tissue-based methods (polymerase chain reaction, immunohistochemistry, and in situ hybridization) and serologic assays (enzyme-linked immunosorbent assay, immunofluorescence, etc.). The objective of this review was to answer the question of whether infection of the male genitourinary tract may have a role in the etiology of CaP. Materials and methods We have carried out a systematic review of the evidence that was published in the MEDLINE/PubMed database until December 2011. The search terms included “prostate cancer,” “infection,” and the explicit names of the various infectious agents. Additional studies were identified using a reference search. A total of 74 papers were included in the review, which cover the following infectious agents: human papillomavirus, cytomegalovirus, herpes simplex virus, Epstein-Barr virus, human herpesvirus, BK virus, JC virus, chlamydia, mycoplasma, ureaplasma, trichomonas, neisseria, treponema, Propionibacterium acnes, xenotropic murine leukemia virus-related virus and Candida albicans. Results Despite the variable study designs and methodological approaches that were used, most of the pathogens that were studied were unlikely to be directly involved in prostate carcinogenesis. Conclusions The role of infection in the etiology of CaP has yet to be determined despite 30 years of research efforts. A discovery of an infectious agent that is associated with CaP would be of great medical importance; however, such a link would have to be firmly established before impacting on patient care.

Currently, there is a lack of phylogenetic footprinting programmes that can take advantage of multiple whole genome sequences of different species within the same bacterial genus. Therefore, we have developed and tested a position weight matrix-based programme called Footy, that performs genome-wide analysis of bacterial genomes for promoters that phylogenetically footprint. When Footy was used to analyse the non-coding regions upstream of genes from three chlamyidal species for promoters that phylogenetically footprint, it predicted a total of 42 promoters, of which 41 were new. Ten of the 41 new promoters predicted by Footy were biologically assayed in Chlamydia trachomatis by mapping the 5' end of the transcripts for the associated genes. The primer extension assay validated seven of the 10 promoters. When Footy was compared to two other accepted methods for genome-wide prediction of promoters in bacteria (the standard PWM method and MITRA), Footy performed equally as well or better than these programmes. This paper, therefore, shows the value of a bioinformatics programme able to perform genome-wide analysis of bacteria for promoters that phylogenetically footprint.

To compare three methods of data collection on case ascertainment of past chlamydia or gonorrhea diagnoses.Data collection for 361 adolescent females between 1998 and 2000 included: 1) face-to-face interviews; 2) computerized and paper medical record reviews; and 3) chlamydia and gonorrhea reports to the state health department. Statistical methods include latent class and composite reference standard analyses.The estimated prevalence of past diagnoses did not differ significantly by data collection method for chlamydia (20.5%, 23.0%, and 19.7% by self-report, medical record reviews, and state health department reports, respectively) or gonorrhea (4.7%, 6.9%, and 5.5%, respectively) during the 2-year study period. The estimated latent class and composite reference standard prevalences for chlamydia were 23.5% and 26.9%, respectively (p=.04 and p.01 for differences from self-report alone, respectively). For gonorrhea, the estimated latent class and composite reference standard prevalences were 7.8% and 6.9%, respectively (p.01 for both differences from self-report alone). Kappa scores for self-report compared with the latent class and composite reference standard prevalences ranged from .67 to .80, and the magnitude of under-reporting ranged from 21% to 47%.The similar case ascertainment from the three sources separately and high reliability of self-report, coupled with its feasibility and low cost, suggest that self-report is a viable data collection method for STD diagnoses. However, using multiple sources may be preferable when time and resources permit given that under-reporting by self-report is likely to occur (particularly for gonorrhea) and that greater case ascertainment can be achieved.

In the United States almost half of all high school students have had sexual intercourse1 and a substantial number more engage in other sexual behaviors that put them at risk for sexually transmitted infections (STI). As a result of a combination of developmental behavioral and biologic factors adolescents are disproportionately affected by STI. Further adolescents are often less likely to present for diagnosis and treatment. The purpose of this paper is to review STI treatment issues that are specific to adolescents with a focus on adolescent women. Table 1 summarizes important features of treatment for each infection. (excerpt)

Community acquired pneumonia (CAP) continues to be a common cause of general practitioner presentation and of acute admission to the paediatric medical ward. These children often have admission venepuncture for full blood counts (FBC) with differential white cell counts (WCC), C-reactive protein (CRP) or erythrocyte sedimentation rates (ESR) and blood cultures as well as chest X-ray (CXR) in an attempt to differentiate a viral from bacterial cause. Several recent papers have reported data from the USA and Europe that investigate the aetiology and most useful diagnostic tests in CAP and to compare responses with treatment with different antibiotics. Drummond et al. reported a group of 136 children aged two weeks to 16 years. At least one pathogen was identified as a definite or probable cause of the pneumonia in 70 children (51%). Fifty (37%) had a virus implicated (mostly respiratory syncytial virus, followed by influenza A, cytomegalovirus and adenovirus) and 19 a bacterium (7% group A streptococcus, 4% Streptococcus pneumoniae). Admission blood tests and CXR did not assist in differentiating viral from bacterial pneumonia but viral immunofluorescence and paired serology were the most useful diagnostic tests. Wubbel et al. reported on 168 children with radiographic and clinical evidence of pneumonia aged 6 months to 16 years from Dallas, Texas. All blood cultures were negative and infecting organisms were identified by acute and convalescent serology, nasopharyngeal and pharyngeal swabs for culture and polymerase chain reaction (PCR) for Chlamydia pneumoniae and Mycoplasma

This paper will concentrate on Chlamydia pneumoniae, whch is the most common non-viral intracellular pathogen and has been a major focus of this Symposium. It has now been 10 years since we first obtained serologic evidence suggesting that the untypeable Chlamydia isolate obtained from the eye of a child in Taiwan in 1965 was associated with respiratory tract infection [l], and then isolated a s d a r strain from acute respiratory hsease 121. While much circumstantial evidence has accumulated that the TwAR organism causes acute respiratory disease, there have been very few appropriately controlled investigations directed at proving an etiologic role for the organism in acute respiratory disease (ARD) [3].

This paper will review the significance of results obtained by DNA amplification methods performed on clinical materials for the detection of bacterial pathogens. They will be compared with conventional culture, antigen detection or serological methods with respect to speed, sensitivity and specificity. PCR has provided promising results in the identification of Bordetella pertussis, Chlamydia pneumoniae, Legionella pneumophila, Streptococcus pneumoniae, Mycoplasma pneumoniae and the various pathogroups of diarrheagenic Escherichia coli. PCR and LCR have also shown encouraging results when used in the diagnosis of sexually transmitted diseases caused by Chlamydia trachomatis. In patients with Lyme disease, the sensitivity of PCR is still insufficient, when compared to serological methods. Here PCR is an adjunct in the diagnosis and no substitute for clinical judgement and serology. PCR applications for the detection of bacterial pathogens in clinical materials have also proved to be both problematic and challenging. Problems in using the PCR include determining the optimal target selection, quantifying the sample volume necessary for analysis, determining a standard for sample preparation, and optimizing amplification reactions. There are also difficulties with PCR inhibitors present in the clinical material and with monitoring the performance of the technique. PCR results are highly reliable and reproducible between laboratories when standardized reagents and protocols are used. An important step in this direction is the commercial availability of PCR kits. Such kits also simplify the handling of PCR, thus requiring less technical expertise, and allowing broader use for diagnosis. In the near future, additional studies must provide a correlation between PCR results and conventional methods with larger numbers of samples. Moreover, as a final evaluation, PCR detection methods must prove their benefit with respect to clinical management.

In 1986, an estimated 13 million cases of sexually transmitted diseases (STDs) were diagnosed in the United States, with the highest incidence rates occurring within the adolescent age group. Homosexual adolescent men are at particularly high risk for STDs. Because of the myriad clinical presentations of STD in gay men, these diseases are often not recognized as being sexually transmitted. In this paper, the epidemiology and clinical features of STDs in gay adolescents are discussed. The sexual history is emphasized as an integral tool in developing a differential diagnosis. A priori, the sexual history also can give a risk-assessment profile for STD. Clinical aspects of STD are reviewed using a syndrome approach, and the diagnostic workup is outlined for the etiologic agents most likely implicated in each syndrome. Clinical signs and symptoms of urethritis, genital ulcers and papular lesions, pharyngitis, and hepatitis are reviewed. Sexually acquired gastrointestinal disorders are described. As the AIDS epidemic continues, disease prevention, risk reduction, and patient education are becoming more important. Current recommendations for "safer sex" practices are reviewed.

Northern Illinois experienced an outbreak of chlamydial infection in 1963, 1964, and 1965, as reflected by an increase in the number of patients showing antibody to this group of agents during the period. Among these individuals, a disproportionately large number with PMD showed serologic activity against Chlamydia. This suggests that there was something distinctive about the response of the PMD patients in the face of this outbreak. The clinical manifestations of heart disease in PMD patients were similar regardless of their serologic status, i.e., whether or not they had antibody of Chlamydia. Specific serum reactivity to Chlamydia was verified by: (1) use of multiple chlamydial antigens, (2) application of both complement-fixation and RIP test systems, and (3) absence of reactivity to uninfected egg tissue or to egg tissue infected with Newcastle disease virus. Reactivity to Chlamydia persisted in our PMD population for periods of months to more than five years. While the evidence cited in this paper linking chlamydial agent to the PMD is inferential and no direct evidence of chlamydial infection was found in the tissue of 12 hearts examined, epidemiologic considerations strongly suggest an etiologic relationship.

Summary This paper reports an incident involving the exposure of eight employees who were handling a strain of Chlamydia in a production process. The report shows how a change of strain can alter the pathogenicity of the organism and how it is important to review handling precautions before any change of strain or procedure is undertaken.