Estimating the population level impact of a gonococcal vaccine candidate: Predictions from a simple mathematical model

BACKGROUND

Neisseria gonorrhoeae cross-protection was suggested in a New Zealand meningitis B vaccine. We modeled the potential impact of similar vaccines on gonorrhea prevalence in heterosexuals in the United States.

METHODS

Our mathematical model incorporated infection, behavior, and vaccination dynamics. Approximate Bayesian Computation calibrated our model to US prevalence. Primary analyses assumed New Zealand vaccine characteristics: 30% efficacy and 2-year duration of protection. We estimated impact under two vaccine coverages (20%, 50%).

RESULTS

Reduction in gonorrhea prevalence ranged from 4.8 to 39.4%, depending on vaccine coverage. Vaccine impact was correlated with both size of the highly sexually active subpopulation and sexual mixing between high and low activity subpopulations.

CONCLUSIONS

A meningitis vaccine providing low efficacy cross-protection against gonorrhea acquisition and short duration of protection could result in a large reduction in gonorrhea prevalence in the United States. Potential dual protective effects can be considered when making vaccine recommendations.

COVID-19 SeroHub, an online repository of SARS-CoV-2 seroprevalence studies in the United States

Seroprevalence studies provide useful information about the proportion of the population either vaccinated against SARS-CoV-2, previously infected with the virus, or both. Numerous studies have been conducted in the United States, but differ substantially by dates of enrollment, target population, geographic location, age distribution, and assays used. This can make it challenging to identify and synthesize available seroprevalence data by geographic region or to compare infection-induced versus combined infection- and vaccination-induced seroprevalence. To facilitate public access and understanding, the National Institutes of Health and the Centers for Disease Control and Prevention developed the COVID-19 Seroprevalence Studies Hub (COVID-19 SeroHub, https://covid19serohub.nih.gov/), a data repository in which seroprevalence studies are systematically identified, extracted using a standard format, and summarized through an interactive interface. Within COVID-19 SeroHub, users can explore and download data from 178 studies as of September 1, 2022. Tools allow users to filter results and visualize trends over time, geography, population, age, and antigen target. Because COVID-19 remains an ongoing pandemic, we will continue to identify and include future studies.

Pooling in a Pod: A Strategy for COVID-19 Testing to Facilitate a Safe Return to School

The COVID-19 pandemic prompted widespread closures of primary and secondary schools. Routine testing of asymptomatic students and staff members, as part of a comprehensive mitigation program, can help schools open safely. “Pooling in a pod” is a public health surveillance strategy whereby testing cohorts (pods) are based on social relationships and physical proximity. Pooled testing provides a single laboratory test result for the entire pod, rather than a separate result for each person in the pod. During the 2020-2021 school year, an independent preschool–grade 12 school in Washington, DC, used pooling in a pod for weekly on-site point-of-care testing of all staff members and students. Staff members and older students self-collected anterior nares samples, and trained staff members collected samples from younger students. Overall, 12 885 samples were tested in 1737 pools for 863 students and 264 staff members from November 30, 2020, through April 30, 2021. The average pool size was 7.4 people. The average time from sample collection to pool test result was 40 minutes. The direct testing cost per person per week was $24.24, including swabs. During the study period, 4 surveillance test pools received positive test results for COVID-19. A post-launch survey found most parents (90.3%), students (93.4%), and staff members (98.8%) were willing to participate in pooled testing with confirmatory tests for pool members who received a positive test result. The proportion of students in remote learning decreased by 62.2% for students in grades 6-12 (P < .001) and by 92.4% for students in preschool to grade 5 after program initiation (P < .001). Pooling in a pod is a feasible, cost-effective surveillance strategy that may facilitate safe, sustainable, in-person schooling during a pandemic.

Toward Understanding COVID-19 Recovery: National Institutes of Health Workshop on Postacute COVID-19

Over the past year, the SARS-CoV-2 pandemic has swept the globe, resulting in an enormous worldwide burden of infection and mortality. However, the additional toll resulting from long-term consequences of the pandemic has yet to be tallied. Heterogeneous disease manifestations and syndromes are now recognized among some persons after their initial recovery from SARS-CoV-2 infection, representing in the broadest sense a failure to return to a baseline state of health after acute SARS-CoV-2 infection. On 3 to 4 December 2020, the National Institute of Allergy and Infectious Diseases, in collaboration with other Institutes and Centers of the National Institutes of Health, convened a virtual workshop to summarize existing knowledge on postacute COVID-19 and to identify key knowledge gaps regarding this condition.

Doxycycline Versus Azithromycin for the Treatment of Rectal Chlamydia in Men Who Have Sex With Men: A Randomized Controlled Trial

BACKGROUND

Azithromycin and doxycycline are both recommended treatments for rectal Chlamydia trachomatis (CT) infection, but observational studies suggest that doxycycline may be more effective.

METHODS

This randomized, double-blind, placebo-controlled trial compared azithromycin (single one-gram dose) vs. doxycycline (100mg twice daily for seven days) for the treatment of rectal CT in men who have sex with men (MSM) in Seattle and Boston. Participants were enrolled after a diagnosis of rectal CT in clinical care and underwent repeated collection of rectal swabs for nucleic acid amplification testing (NAAT) at study enrollment, two weeks, and four weeks post-enrollment. The primary outcome was microbiologic cure (CT-negative NAAT) at four weeks. The complete case (CC) population included participants with a CT-positive NAAT at enrollment and a follow-up NAAT result; the intention-to-treat (ITT) population included all randomized participants.

RESULTS

Among 177 participants enrolled, 135 (76%) met CC population criteria for the four-week follow-up visit. Thirty-three participants (19%) were excluded because the CT NAAT repeated at enrollment was negative. Microbiologic cure was higher with doxycycline than azithromycin in both the CC population [100% (70 of 70) vs. 74% (48 of 65); absolute difference 26% (95% CI: 16-36%; p<0.001)] and the ITT population [91% (80 of 88) vs. 71% (63 of 89); absolute difference 20% (95% CI: 9-31%; p<0.001)].

CONCLUSIONS

A one-week course of doxycycline was significantly more effective than a single dose of azithromycin for the treatment of rectal CT in MSM. (Funded by National Institute of Allergy & Infectious Diseases contract HHSN272201300014I, Protocol 17-0092).

Acceptability and feasibility of dual HIV and syphilis point-of-care testing for early detection of infection among pregnant women in China: a prospective study

OBJECTIVE

To assess the feasibility and acceptability of using WHO prequalified combined dual HIV/syphilis rapid diagnostic tests (RDT) for same-day results in antenatal care (ANC) clinics.

METHODS

This is a pragmatic implementation study using quantitative approach to evaluate outcomes. Antenatal clinic attendees from 21 rural and urban township hospitals in two provinces of China were offered with free dual RDTs testing that included HIV and syphilis, in addition to the routine blood tests. Study outcomes included testing uptake before and during dual RDT use, test feasibility and acceptability among pregnant women. Regression model was used to assess acceptance of RDT testing.

RESULTS

In total, 1787 out of 1828 pregnant women attending ANC received the RDT testing. Testing uptake among pregnant women in their first and second trimester increased from 76.0% (2438/3269) using standard blood testing to 90.1% (1626/1787) with concurrent RDT use (χ2=197.1, p<0.001). Among 1787 pregnant women who received RDT tests, 98.3% (1757/1787) participants were given test result the same day. Positive proportions of HIV and syphilis screened with RDT were 0.06% (1/1787) and 1.0% (18/1787), respectively. Regression analysis indicated that women who did not receive syphilis or HIV testing before were less likely to accept dual RDT (OR 0.28, 95% CI 0.10 to 0.75). Acceptance for dual RDT testing at second or third antenatal visit was lower compared with the first visit (OR 0.37, 95% CI 0.15 to 0.94).

CONCLUSION

Combined dual HIV/syphilis RDT with same-day results increased uptake of HIV and syphilis testing among pregnant women at primary healthcare facilities. Given the diversity of testing capacities among health services especially in rural areas in China, the dual RDT kit is feasible tool to improve testing uptake among pregnant women.

Global burden of maternal and congenital syphilis in 2008 and 2012: a health systems modelling study

Summary

Background

In 2007, WHO launched a global initiative for the elimination of mother-to-child transmission of syphilis (congenital syphilis). An important aspect of the initiative is strengthening surveillance to monitor progress towards elimination. In 2008, using a health systems model with country data inputs, WHO estimated that 1 4 million maternal syphilis infections caused 520 000 adverse pregnancy outcomes. To assess progress, we updated the 2008 estimates and estimated the 2012 global prevalence and cases of maternal and congenital syphilis.

Methods

We used a health systems model approved by the Child Health Epidemiology Reference Group. WHO and UN databases provided inputs on livebirths, antenatal care coverage, and syphilis testing, seropositivity, and treatment in antenatal care. For 2012 estimates, we used data collected between 2009 and 2012. We updated the 2008 estimates using data collected between 2000 and 2008, compared these with 2012 estimates using data collected between 2009 and 2012, and performed subanalyses to validate results.

Findings

In 2012, an estimated 930 000 maternal syphilis infections caused 350 000 adverse pregnancy outcomes including 143 000 early fetal deaths and stillbirths, 62 000 neonatal deaths, 44 000 preterm or low weight births, and 102 000 infected infants worldwide. Nearly 80% of adverse outcomes (274 000) occurred in women who received antenatal care at least once. Comparing the updated 2008 estimates with the 2012 estimates, maternal syphilis decreased by 38% (from 1 488 394 cases in 2008 to 927 936 cases in 2012) and congenital syphilis decreased by 39% (from 576 784 to 350 915). India represented 65% of the decrease. Analysis excluding India still showed an 18% decrease in maternal and congenital cases of syphilis worldwide.

Interpretation

Maternal and congenital syphilis decreased worldwide from 2008 to 2012, which suggests progress towards the elimination of mother-to-child transmission of syphilis. Nonetheless, maternal syphilis caused substantial adverse pregnancy outcomes, even in women receiving antenatal care. Improved access to quality antenatal care, including syphilis testing and treatment, and robust data are all important for achieving the elimination of mother-to-child transmission of syphilis.

Funding

The UNDP-UNFPA-UNICEF-WHO-World Bank Special Programme of Research, Development and Research Training in Human Reproduction in WHO, and the US Centers for Disease Control and Prevention.

First estimates of the global and regional incidence of neonatal herpes infection

Background

Neonatal herpes is a rare but potentially devastating condition (60% fatality without treatment). Transmission usually occurs during delivery from mothers with herpes simplex virus type 1 (HSV-1) or HSV-2 genital infection. The global burden has never been quantified. We developed a novel methodology for burden estimation and present first WHO global and regional estimates of the annual number of neonatal herpes cases during 2010–2015.

Methods

Previous estimates of HSV-1 and HSV-2 prevalence and incidence in women aged 15–49 years were applied to 2010–2015 birth rates to estimate infections during pregnancy. Published risks of neonatal HSV transmission were then applied according to whether maternal infection was incident or prevalent with HSV-1 or HSV-2 to estimate neonatal herpes cases.

Findings

Globally the overall rate of neonatal herpes was estimated to be ~10 cases per 100,000 births, equivalent to a best-estimate of ~14,000 cases annually (HSV-1: ~4,000; HSV-2: ~10,000). We estimated that the most neonatal herpes cases occurred in Africa, due to high maternal HSV-2 infection and high birth rates. HSV-1 contributed more cases than HSV-2 in the Americas, Europe and Western Pacific. High rates of genital HSV-1 infection and moderate HSV-2 prevalence meant the Americas had the highest overall rate. However, our estimates are highly sensitive to the core assumptions, and considerable uncertainty exists for many settings given sparse underlying data.

Interpretation

These neonatal herpes estimates mark the first attempt to quantify the global burden of this rare but serious condition. Better primary data collection on neonatal herpes is critically needed to reduce uncertainty and refine future estimates. This is particularly important in resource-poor settings where we may have underestimated cases. Nevertheless, these first estimates suggest development of new HSV prevention measures such as vaccines could have additional benefits beyond reducing genital ulcer disease and HSV-associated HIV transmission, through prevention of neonatal herpes.

Funding

World Health Organization

Assessment of Geographic Information Systems and Data Confidentiality Guidelines in STD Programs

OBJECTIVE

Advancements in technology, such as geographic information systems (GIS), expand sexually transmitted disease (STD) program capacity for data analysis and visualization, and introduce additional confidentiality considerations. We developed a survey to examine GIS use among STD programs and to better understand existing data confidentiality practices.

METHODS

A Web-based survey of eight to 22 questions, depending on program-specific GIS capacity, was e-mailed to all STD program directors through the National Coalition of STD Directors in November 2004. Survey responses were accepted until April 15, 2005.

RESULTS

Eighty-five percent of the 65 currently funded STD programs responded to the survey. Of those, 58% used GIS and 54% used geocoding. STD programs that did not use GIS (42%) identified lack of training and insufficient staff as primary barriers. Mapping, spatial analyses, and targeting program interventions were the main reasons for geocoding data. Nineteen of the 25 programs that responded to questions related to statistical disclosure rules employed a numerator rule, and 56% of those used a variation of the "Rule of 5." Of the 28 programs that responded to questions pertaining to confidentiality guidelines, 82% addressed confidentiality of GIS data informally.

CONCLUSIONS

Survey findings showed the increasing use of GIS and highlighted the struggles STD programs face in employing GIS and protecting confidentiality. Guidance related to data confidentiality and additional access to GIS software and training could assist programs in optimizing use of spatial data.

Here Comes the SSuN: Early Experiences with the STD Surveillance Network

In 2005, the Centers for Disease Control and Prevention established the STD Surveillance Network (SSuN), a sentinel surveillance system comprising local, enhanced sexually transmitted disease (STD) surveillance systems that follow common protocols. The purpose of SSuN is to improve the capacity of national, state, and local STD programs to detect, monitor, and respond rapidly to trends in STDs through enhanced collection, reporting, analysis, visualization, and interpretation of clinical, behavioral, and geographic information obtained from a geographically diverse sample of individuals diagnosed with STDs. To demonstrate the utility of a national sentinel surveillance network, this article reviews the lessons learned from the first three years of SSuN, which, through its enhanced gonorrhea and genital warts sentinel surveillance projects, has proved to be a useful adjunct to routine STD surveillance in the U.S. that can be expanded into other areas of STD public health interest.

Practical Considerations for Matching STD and HIV Surveillance Data with Data from Other Sources

Data to guide programmatic decisions in public health are needed, but frequently epidemiologists are limited to routine case report data for notifiable conditions such as sexually transmitted diseases (STDs) and human immunodeficiency virus (HIV). However, case report data are frequently incomplete or provide limited information on comorbidity or risk factors. Supplemental data often exist but are not easily accessible, due to a variety of real and perceived obstacles. Data matching, defined as the linkage of records across two or more data sources, can be a useful method to obtain better or additional data, using existing resources. This article reviews the practical considerations for matching STD and HIV surveillance data with other data sources, including examples of how STD and HIV programs have used data matching.

Global and Regional Estimates of Prevalent and Incident Herpes Simplex Virus Type 1 Infections in 2012

Background

Herpes simplex virus type 1 (HSV-1) commonly causes orolabial ulcers, while HSV-2 commonly causes genital ulcers. However, HSV-1 is an increasing cause of genital infection. Previously, the World Health Organization estimated the global burden of HSV-2 for 2003 and for 2012. The global burden of HSV-1 has not been estimated.

Methods

We fitted a constant-incidence model to pooled HSV-1 prevalence data from literature searches for 6 World Health Organization regions and used 2012 population data to derive global numbers of 0-49-year-olds with prevalent and incident HSV-1 infection. To estimate genital HSV-1, we applied values for the proportion of incident infections that are genital.

Findings

We estimated that 3709 million people (range: 3440–3878 million) aged 0–49 years had prevalent HSV-1 infection in 2012 (67%), with highest prevalence in Africa, South-East Asia and Western Pacific. Assuming 50% of incident infections among 15-49-year-olds are genital, an estimated 140 million (range: 67–212 million) people had prevalent genital HSV-1 infection, most of which occurred in the Americas, Europe and Western Pacific.

Conclusions

The global burden of HSV-1 infection is huge. Genital HSV-1 burden can be substantial but varies widely by region. Future control efforts, including development of HSV vaccines, should consider the epidemiology of HSV-1 in addition to HSV-2, and especially the relative contribution of HSV-1 to genital infection.

Introduction of rapid syphilis testing in antenatal care: A systematic review of the impact on HIV and syphilis testing uptake and coverage

BACKGROUND

Global guidelines recommend universal syphilis and HIV screening for pregnant women. Rapid syphilis testing (RST) may contribute toward achievement of universal screening.

OBJECTIVES

To examine the impact of RST on syphilis and HIV screening among pregnant women.

SEARCH STRATEGY

We searched MEDLINE for English- and non-English language articles published through November, 2014.

SELECTION CRITERIA

We included studies that used a comparative design and reported on syphilis and HIV test uptake among pregnant women in low- and middle-income countries (LMICs) following introduction of RST.

DATA COLLECTION AND ANALYSIS

Data were extracted from six eligible articles presenting findings from Asia, Africa, and Latin America.

MAIN RESULTS

All studies reported substantial increases in antenatal syphilis testing following introduction of RST; the latter did not appear to adversely impact antenatal HIV screening levels at sites already offering rapid HIV testing and may increase HIV screening among pregnant women in some settings. Qualitative data revealed that women were highly satisfied with RST. Nevertheless, ensuring adequate training for healthcare workers and supplies of commodities were cited as key implementation barriers.

CONCLUSIONS

RST may increase antenatal syphilis and HIV screening and contribute to the improvement of antenatal care in LMICs.

Laboratory evaluation of three dual rapid diagnostic tests for HIV and syphilis in China and Nigeria

OBJECTIVE

To determine the laboratory-based performance and operational characteristics of three dual rapid diagnostic tests (RDTs) for testing HIV and syphilis.

METHODS

Three dual RDTs (SD Bioline, Chembio, and MedMira) were evaluated using 1514 serum specimens archived at laboratories or collected from clinics in China and Nigeria to determine sensitivity and specificity, with 95% confidence intervals. Concordance of testing results read by two technicians, stability of testing results read at two time points, and test operation characteristics were also assessed.

RESULTS

All three of the evaluated RDTs gave excellent performance with a combined sensitivity ranging from 99.0%-99.6% for HIV and 98.3%-99.0% for syphilis, and a combined specificity ranging from 97.9%-99.0% for HIV and 97.2%-99.6% for syphilis. Concordance of testing results between two technicians and stability of testing results read within and one hour past the recommended reading period showed excellent agreement, with Kappa greater than or equal to 0.98.

CONCLUSIONS

All the tests were found to be very or fairly easy to use and easy to interpret the results. Further evaluations of these dual RDTs with whole blood in field settings, and more studies on the implication of introduction of these tests in HIV and syphilis control programs are needed.

Estimating disease burden of maternal syphilis and associated adverse pregnancy outcomes in India, Nigeria, and Zambia in 2012

OBJECTIVE

To estimate maternal syphilis and its associated adverse pregnancy outcomes in India, Nigeria, and Zambia.

METHODS

An online estimation tool was used to generate point estimates and uncertainty ranges of maternal syphilis and adverse pregnancy outcomes due to mother-to-child transmission (MTCT). The most recent data (2010-2012) on antenatal care coverage, syphilis seroprevalence, and syphilis screening and treatment coverage at the subnational level in India, Nigeria, and Zambia were used to estimate disease burden for 2012. Sensitivity analysis was conducted for three screening and treatment scenarios (current coverages, current coverages minus 20%, and ideal coverages consistent with WHO targets for eliminating MTCT of syphilis).

RESULTS

A total of 103 960, 74 798, and 9072 pregnant women with probable active syphilis were estimated to occur in India, Nigeria, and Zambia, resulting in 53 187, 37 045, and 2973 adverse outcomes, respectively; approximately 1.6%, 4.8%, and 37.0% of these were averted under the current service coverages in India, Nigeria, and Zambia. The disease burden varied significantly in its subnational distribution within India and Nigeria, but was distributed evenly across Zambia.

CONCLUSIONS

The obtained results suggest an ongoing, unaverted high burden of maternal syphilis and associated adverse outcomes in India, Nigeria, and Zambia. Screening and treatment for syphilis must be scaled-up significantly in these countries to achieve elimination of MTCT of syphilis.

Global estimates of prevalent and incident herpes simplex virus type 2 infections in 2012

Background

Herpes simplex virus type 2 (HSV-2) infection causes significant disease globally. Adolescent and adult infection may present as painful genital ulcers. Neonatal infection has high morbidity and mortality. Additionally, HSV-2 likely contributes substantially to the spread of HIV infection. The global burden of HSV-2 infection was last estimated for 2003. Here we present new global estimates for 2012 of the burden of prevalent (existing) and incident (new) HSV-2 infection among females and males aged 15–49 years, using updated methodology to adjust for test performance and estimate by World Health Organization (WHO) region.

Methods and Findings

We conducted a literature review of HSV-2 prevalence studies world-wide since 2000. We then fitted a model with constant HSV-2 incidence by age to pooled HSV-2 prevalence values by age and sex. Prevalence values were adjusted for test sensitivity and specificity. The model estimated prevalence and incidence by sex for each WHO region to obtain global burden estimates. Uncertainty bounds were computed by refitting the model to reflect the variation in the underlying prevalence data. In 2012, we estimate that there were 417 million people aged 15–49 years (range: 274–678 million) living with HSV-2 infection world-wide (11.3% global prevalence), of whom 267 million were women. We also estimate that in 2012, 19.2 million (range: 13.0–28.6 million) individuals aged 15–49 years were newly-infected (0.5% of all individuals globally). The highest burden was in Africa. However, despite lower prevalence, South-East Asia and Western Pacific regions also contributed large numbers to the global totals because of large population sizes.

Conclusions

The global burden of HSV-2 infection is large, leaving over 400 million people at increased risk of genital ulcer disease, HIV acquisition, and transmission of HSV-2 to partners or neonates. These estimates highlight the critical need for development of vaccines, microbicides, and other new HSV prevention strategies.

Can the Perinatal Information System in Peru be used to measure the proportion of adverse birth outcomes attributable to maternal syphilis infection?

OBJECTIVE

To describe the capacity of Peru's Perinatal Information System (Sistema Informático Perinatal, SIP) to provide estimates for monitoring the proportion of stillbirths and other adverse birth outcomes attributable to maternal syphilis.

METHODS

A descriptive study was conducted to assess the quality and completeness of SIP data from six Peruvian public hospitals that used the SIP continuously from 2000 - 2010 and had maternal syphilis prevalence of at least 0.5% during that period. In-depth interviews were conducted with Peruvian stakeholders about their experiences using the SIP.

RESULTS

Information was found on 123 575 births from 2000 - 2010 and syphilis test results were available for 99 840 births. Among those 99 840 births, there were 1 075 maternal syphilis infections (1.1%) and 619 stillbirths (0.62%). Among women with syphilis infection in pregnancy, 1.7% had a stillbirth, compared to 0.6% of women without syphilis infection. Much of the information needed to estimate the proportion of stillbirths attributable to maternal syphilis was available in the SIP, with the exception of syphilis treatment information, which was not collected. However, SIP data collection is complex and time-consuming for clinicians. Data were unlinked across hospitals and not routinely used or quality-checked. Despite these limitations, the SIP data examined were complete and valid; in 98% of records, information on whether or not the infant was stillborn was the same in both the SIP and clinical charts. Nearly 89% of women had the same syphilis test result in clinical charts and the SIP.

CONCLUSIONS

The large number of syphilis infections reported in Peru's SIP and the ability to link maternal characteristics to newborn outcomes make the system potentially useful for monitoring the proportion of stillbirths attributable to congenital syphilis in Peru. To ensure good data quality and sustainability of Peru's SIP, data collection should be simplified and information should be continually quality-checked and used for the benefit of participating facilities.

Toward global prevention of sexually transmitted infections (STIs): the need for STI vaccines

An estimated 499 million curable sexually transmitted infections (STIs; gonorrhea, chlamydia, syphilis, and trichomoniasis) occurred globally in 2008. In addition, well over 500 million people are estimated to have a viral STI such as herpes simplex virus type 2 (HSV-2) or human papillomavirus (HPV) at any point in time. STIs result in a large global burden of sexual, reproductive, and maternal-child health consequences, including genital symptoms, pregnancy complications, cancer, infertility, and enhanced HIV transmission, as well as important psychosocial consequences and financial costs. STI control strategies based primarily on behavioral primary prevention and STI case management have had clear successes, but gains have not been universal. Current STI control is hampered or threatened by several behavioral, biological, and implementation challenges, including a large proportion of asymptomatic infections, lack of feasible diagnostic tests globally, antimicrobial resistance, repeat infections, and barriers to intervention access, availability, and scale-up. Vaccines against HPV and hepatitis B virus offer a new paradigm for STI control. Challenges to existing STI prevention efforts provide important reasons for working toward additional STI vaccines. We summarize the global epidemiology of STIs and STI-associated complications, examine challenges to existing STI prevention efforts, and discuss the need for new STI vaccines for future prevention efforts.

The cost and cost-effectiveness of scaling up screening and treatment of syphilis in pregnancy: a model

BACKGROUND

Syphilis in pregnancy imposes a significant global health and economic burden. More than half of cases result in serious adverse events, including infant mortality and infection. The annual global burden from mother-to-child transmission (MTCT) of syphilis is estimated at 3.6 million disability-adjusted life years (DALYs) and $309 million in medical costs. Syphilis screening and treatment is simple, effective, and affordable, yet, worldwide, most pregnant women do not receive these services. We assessed cost-effectiveness of scaling-up syphilis screening and treatment in existing antenatal care (ANC) programs in various programmatic, epidemiologic, and economic contexts.

METHODS AND FINDINGS

We modeled the cost, health impact, and cost-effectiveness of expanded syphilis screening and treatment in ANC, compared to current services, for 1,000,000 pregnancies per year over four years. We defined eight generic country scenarios by systematically varying three factors: current maternal syphilis testing and treatment coverage, syphilis prevalence in pregnant women, and the cost of healthcare. We calculated program and net costs, DALYs averted, and net costs per DALY averted over four years in each scenario. Program costs are estimated at $4,142,287 - $8,235,796 per million pregnant women (2010 USD). Net costs, adjusted for averted medical care and current services, range from net savings of $12,261,250 to net costs of $1,736,807. The program averts an estimated 5,754 - 93,484 DALYs, yielding net savings in four scenarios, and a cost per DALY averted of $24 - $111 in the four scenarios with net costs. Results were robust in sensitivity analyses.

CONCLUSIONS

Eliminating MTCT of syphilis through expanded screening and treatment in ANC is likely to be highly cost-effective by WHO-defined thresholds in a wide range of settings. Countries with high prevalence, low current service coverage, and high healthcare cost would benefit most. Future analyses can be tailored to countries using local epidemiologic and programmatic data.

Sexually transmitted infections and women's sexual and reproductive health

Sexually transmitted infections (STIs) are widespread globally and result in a large burden of sexual and reproductive health consequences that disproportionately affect women, including pregnancy complications, cancer, infertility, and enhanced HIV transmission. A new WHO publication, available online, outlines key points of action and new and future technologies for global STI prevention and control. Highlights from the WHO publication are described in the present article.

Untreated maternal syphilis and adverse outcomes of pregnancy: a systematic review and meta-analysis

OBJECTIVE

To perform a systematic review and meta-analysis of reported estimates of adverse pregnancy outcomes among untreated women with syphilis and women without syphilis.

METHODS

PubMed, EMBASE and Cochrane Libraries were searched for literature assessing adverse pregnancy outcomes among untreated women with seroreactivity for Treponema pallidum infection and non-seroreactive women. Adverse pregnancy outcomes were fetal loss or stillbirth, neonatal death, prematurity or low birth weight, clinical evidence of syphilis and infant death. Random-effects meta-analyses were used to calculate pooled estimates of adverse pregnancy outcomes and, where appropriate, heterogeneity was explored in group-specific analyses.

FINDINGS

Of the 3258 citations identified, only six, all case-control studies, were included in the analysis. Pooled estimates showed that among untreated pregnant women with syphilis, fetal loss and stillbirth were 21% more frequent, neonatal deaths were 9.3% more frequent and prematurity or low birth weight were 5.8% more frequent than among women without syphilis. Of the infants of mothers with untreated syphilis, 15% had clinical evidence of congenital syphilis. The single study that estimated infant death showed a 10% higher frequency among infants of mothers with syphilis. Substantial heterogeneity was found across studies in the estimates of all adverse outcomes for both women with syphilis (66.5% [95% confidence interval, CI: 58.0-74.1]; I(2) = 91.8%; P < 0.001) and women without syphilis (14.3% [95% CI: 11.8-17.2]; I(2) = 95.9%; P < 0.001).

CONCLUSION

Untreated maternal syphilis is associated with adverse pregnancy outcomes. These findings can inform policy decisions on resource allocation for the detection of syphilis and its timely treatment in pregnant women.

Safety of benzathine penicillin for preventing congenital syphilis: a systematic review

OBJECTIVE

To estimate the risk of serious adverse reactions to benzathine penicillin in pregnant women for preventing congenital syphilis.

METHODS

We searched for clinical trials or cohorts that assessed the incidence of serious adverse reactions to benzathine penicillin in pregnant women and the general population (indirect evidence). MEDLINE, EMBASE, Scopus and other databases were searched up to December 2012. The GRADE approach was used to assess quality of evidence. Absolute risks of each study were calculated along with their 95% confidence intervals (95% CI). We employed the DerSimonian and Laird random effects model in the meta-analyses.

RESULTS

From 2,765 retrieved studies we included 13, representing 3,466,780 patients. The studies that included pregnant women were conducted to demonstrate the effectiveness of benzathine penicillin: no serious adverse reactions were reported among the 1,244 pregnant women included. In the general population, among 2,028,982 patients treated, 4 died from an adverse reaction. The pooled risk of death was virtually zero. Fifty-four cases of anaphylaxis were reported (pooled absolute risk = 0.002%; 95% CI: 0%-0.003% I(2) = 12%). From that estimate, penicillin treatment would be expected to result in an incidence of 0 to 3 cases of anaphylaxis per 100,000 treated. Any adverse reactions were reported in 6,377 patients among 3,465,322 treated with penicillin (pooled absolute risk = 0.169%; 95% CI: 0.073%-0.265% I(2) = 97%). The quality of evidence was very low.

CONCLUSION

Studies that assessed the risk of serious adverse events due to benzathine penicillin treatment in pregnant women were scarce, but no reports of adverse reactions were found. The incidence of severe adverse outcomes was very low in the general population. The risk of treating pregnant women with benzathine penicillin to prevent congenital syphilis appears very low and does not outweigh its benefits. Further research is needed to improve the quality of evidence.

Changes in fluoroquinolone use for gonorrhea following publication of revised treatment guidelines

OBJECTIVES

We evaluated the impact of revised national treatment recommendations on fluoroquinolone use for gonorrhea in selected states.

METHODS

We evaluated gonorrhea cases reported through the Sexually Transmitted Disease Surveillance Network as treated between July 1, 2006 and May 31, 2008, using interrupted time series analysis. Outcomes were fluoroquinolone treatment overall, by area, and by practice setting.

RESULTS

Of 16,126 cases with treatment dates in this period, 15,669 noted the medication used. After revised recommendations were released, fluoroquinolone use decreased abruptly overall (21.5%; 95% confidence interval [CI] = 15.9%, 27.2%), in most geographic areas evaluated, and in sexually transmitted disease clinics (28.5%; 95% CI = 19.0%, 37.9%). More gradual decreases were seen in primary care (8.6%; 95% CI = 2.6%, 14.6%), and in emergency departments, urgent care, and hospitals (2.7%; 95% CI = 1.7%, 3.7%).

CONCLUSIONS

Fluoroquinolone use decreased after the publication of revised national guidelines, particularly in sexually transmitted disease clinics. Additional mechanisms are needed to increase the speed and magnitude of changes in prescribing in primary care, emergency departments, urgent care, and hospitals.

Bacterial vaginosis, alterations in vaginal flora and HIV genital shedding among HIV-1-infected women in Mozambique

Objectives. We investigated whether abnormal vaginal flora, including bacterial vaginosis (BV), are associated with detection of cervical HIV-1 RNA among HIV-infected women in Mozambique. Methods. We obtained clinical data and vaginal specimens from HIV-infected women registering for their first visit at one of two HIV care clinics in Mozambique. We compared women with detectable cervical HIV viral load (≥40 copies/ml) with women with undetectable cervical HIV. Results. We enrolled 106 women. Women with abnormal vaginal flora (intermediate Nugent scores, 4 - 6) were more likely to have detectable cervical HIV RNA then women with normal vaginal flora (adjusted odds ratio 7.2 (95% confidence interval 1.8 - 29.1), adjusted for CD4 count). Women with BV had a non-significantly higher likelihood of detectable cervical HIV than women with normal flora. Conclusions. Abnormal vaginal flora were significantly associated with cervical HIV expression. Further research is needed to confirm this relationship.

A road map for the global elimination of congenital syphilis

Congenital syphilis is the oldest recognized congenital infection, and continues to account for extensive global perinatal morbidity and mortality today. Serious adverse pregnancy outcomes caused by maternal syphilis infection are prevented with screening early in pregnancy and prompt treatment of women testing positive. Intramuscular penicillin, an inexpensive antibiotic on the essential medicine list of nations all over the world, effectively cures infection and prevents congenital syphilis. In fact, at a cost of $11-15 per disability adjusted life year (DALY) averted, maternal syphilis screening and treatment is among the most cost-effective public health interventions in existence. Yet implementation of this basic public health intervention is sporadic in countries with highest congenital syphilis burden. We discuss the global burden of this devastating disease, current progress and ongoing challenges for its elimination in countries with highest prevalence, and next steps in ensuring a world free of preventable perinatal deaths caused by syphilis.

Update on the management of gonorrhea in adults in the United States

Gonorrhea, the second most commonly reported notifiable disease, is an important cause of cervicitis, urethritis, and pelvic inflammatory disease. The selection of appropriate therapy for gonorrhea (i.e., safe, highly effective, single dose, and affordable) is complicated by the ability of Neisseria gonorrhoeae to develop resistance to antimicrobial therapies. This article reviews the key questions and data that informed the 2006 gonorrhea treatment recommendations of the Centers for Disease Control and Prevention. Key areas addressed include the criteria used to select effective treatment for gonorrhea, the level of antimicrobial resistance at which changing treatment regimens is recommended, the epidemiology of resistance, and the use of quinolones, cephalosporins, and other classes of antimicrobials for the treatment of uncomplicated gonorrhea.

Predicting Subsequent Infection in Patients Attending Sexually Transmitted Disease Clinics

OBJECTIVE/GOAL

The objective of this study was to identify characteristics associated with subsequent infection in patients attending a sexually transmitted disease (STD) clinic.

STUDY DESIGN

Records were retrospectively reviewed for patients from public STD clinics in 4 cities for 12 months after their initial visit to assess subsequent infection with gonorrhea, chlamydia, mucopurulent cervicitis, nongonococcal urethritis, pelvic inflammatory disease, primary or secondary syphilis, or trichomoniasis.

RESULTS

Among 64,463 patients, 33.9% had an initial STD and 7.0% had a subsequent STD. Patients with an initial STD had significantly higher probability of a subsequent STD than patients without (12.0% vs. 4.4%). A subsequent STD was significantly more likely for both sexes for those with an initial STD, who were symptomatic at initial visit, reporting exchange of sex, or under age 20 as well as for men reporting sex with men.

CONCLUSIONS

Patients with an initial STD were more likely to return with a subsequent STD. Routinely collected information such as initial diagnosis or age can help identify patients at increased risk of a subsequent STD.

The Epidemiology of Fluoroquinolone‐ResistantNeisseria gonorrhoeaein Hawaii, 2001

Increases in the number of infections with fluoroquinolone-resistant Neisseria gonorrhoeae in Asia and the United States threaten the efficacy of fluoroquinolones as inexpensive, single-dose, orally administered treatments for gonorrhea. This report describes the findings of a field investigation of an increase in the number of infections with ciprofloxacin-resistant N. gonorrhoeae (CipRGC) in Hawaii in 2001. We conducted a case review of 53 patients with CipRGC, who constituted 20% of the 267 patients with cultures positive for N. gonorrhoeae during this period. Nearly one-half of patients with CipRGC were seen by clinicians in private practice, one-third were seen by clinicians at a sexually transmitted diseases (STD) clinic, and only 2% were seen by clinicians in the military. Among the 117 patients with culture-confirmed gonorrhea who attended the public STD clinic, we found a prevalence of infection with CipRGC of 17%. The demographic and clinical characteristics of patients with CipRGC were similar to those of patients with gonorrhea that was not resistant to ciprofloxacin, suggesting that fluoroquinolone-resistant gonorrhea has become endemic in Hawaii.

HIV seroprevalence among military blood donors in Manica Province, Mozambique

HIV seroprevalence data show an alarming HIV situation in central Mozambique, but little is known about the situation of HIV in Mozambican military personnel. This study is a retrospective analysis of laboratory records for voluntary blood donors at a rural hospital from January 1997 through December 1999. The hospital screened blood samples with HIV SPOT rapid test for HIV and rapid plasma reagin (RPR) serological test for syphilis. Of the 797 blood donors during this period, 110 (13.8%) were military personnel of whom 39.1% were HIV positive (35.0% in 1997, 33.3% in 1998 and 48.7% in 1999). Among the 687 nonmilitary donors 15.3% were HIV positive (P<0.0001 vs military). 74.4% of HIV-positive military personnel were also RPR positive. Conversely, only 3.0% of HIV-negative military donors were RPR positive. In light of the high rates of HIV and syphilis in military personnel, aggressive intervention measures must be taken to prevent and treat HIV and STDs in this population.

Pediatric wilderness recreational deaths in western Washington State

STUDY OBJECTIVE

To determine the causes and characteristics of pediatric recreational wilderness deaths.

METHODS

All deaths of children between 12 months and 20 years of age involving a wilderness recreational activity in 5 western Washington counties between 1987 and 1996 were identified by medical examiners' logs. Univariate analysis was used to examine variables such as age, gender, activity, mechanism of injury, adult presence, blood alcohol level, safety equipment, and mode of evacuation.

RESULTS

Of 40 cases meeting inclusion criteria, 90% involved male subjects and 83% of victims were 13 to 19 years old. Hiking (33%), swimming (20%), and river rafting (10%) were the most common activities. Death was most often by drowning (55%) or closed head injury (26%). No victim was alone. All children younger than 10 years of age were accompanied by an adult, in contrast to only 26% of individuals 10 years or older. Only 4 victims had drugs or alcohol in their system. No victim wore a personal flotation device or helmet, and only 5% had foul weather gear. Although nearly one third of victims were transported by airlift, more than half of the victims were dead at the scene.

CONCLUSION

Males and teenagers were the 2 major risk groups for recreational wilderness deaths. Traditional activities such as hiking and swimming were the most common causes of death. Children younger than 10 years died despite the presence of an adult, whereas teenagers were usually with groups of peers. The majority of victims were not prepared for adverse events with basic safety equipment.

Intrathecal bupivacaine reduces pruritus and prolongs duration of fentanyl analgesia during labor: a prospective, randomized controlled trial

Pruritus is a frequent complication (40%-100%) of intrathecal (IT) fentanyl 25 microg (F) for labor analgesia. The addition of IT bupivacaine 2.5 mg (B) to F has been reported in a nonrandomized series to have a 17.3% incidence of pruritus. This study prospectively evaluated the incidence and distribution of pruritus in laboring parturients receiving IT F + B. Sixty-five laboring parturients were randomly assigned to receive IT F, B, or F + B as part of a combined spinal-epidural technique. Visual analog scores, sensory level, motor strength, and pruritus were recorded before injection and at intervals thereafter. When present, the distribution of pruritus was evaluated. The duration of analgesia was determined as the time from IT drug administration until the patient requested supplemental analgesia. The median duration of analgesia in the F, B, and F + B groups was 62.5, 55.0, and 94.5 min, respectively. Compared with F alone, the combination of F + B led to a decreased frequency of pruritus (36.4% vs 95%). The incidence of facial pruritus (25%) was same in the F + B and F groups; however, the occurrence of pruritus distributed over the rest of the body was significantly more frequent in the F compared with the F + B group. The combination of F + B prolongs the duration of labor analgesia compared with IT F or B alone. F + B also leads to a decreased incidence of pruritus, except in the facial region.

IMPLICATIONS

When administered intrathecally with fentanyl 25 microg in laboring parturients, bupivacaine 2.5 mg attenuates the frequency of pruritus on all parts of the body except the face. This combination also results in a rapid onset and prolonged duration of labor analgesia compared with either drug alone.

An in vivo evaluation of four spinal needles used for the combined spinal-epidural technique

The purpose of this study was to evaluate four pencil-point spinal needles commonly used for combined spinal-epidural (CSE) anesthesia. Four hundred-seven consecutive parturients undergoing cesarean delivery or labor analgesia received a CSE block with a randomly selected pencil-point spinal needle (Becton-Dickinson [B-D] 27-gauge, 119-mm Whitacre; B-D 27-gauge, 120-mm Durasafe; B-D 25-gauge, 120-mm Durasafe; or International Medical Devices' 26-gauge, 124-mm Gertie Marx). Success in obtaining cerebrospinal fluid (CSF) and the incidence of transient paresthesias and postdural puncture headache (PDPH) were compared by using chi2 testing; P < 0.05 was considered significant. Failure to obtain CSF (3%-5%) was not significantly different among spinal needles. The Gertie Marx 26-gauge needle was associated with significantly more paresthesias (29%) than the Whitacre 27-gauge needle (17%). The combined incidence of paresthesias with the Durasafe 25-gauge and Gertie Marx 26-gauge spinal needles (28%) was greater than the combined incidence of paresthesias with the Durasafe 27-gauge and Whitacre 27-gauge needles (18%). The incidence of PDPH did not differ among the four pencil-point spinal needles. We conclude that longer spinal needles are associated with a significantly more frequent incidence of transient paresthesias without residual effects.

IMPLICATIONS

The use of four pencil-point spinal needles in the combined spinal-epidural technique is associated with an inconsequential incidence of spinal headache, a low incidence of paresthesias that are transient with no long-term effects, and a high degree of success independent of spinal needle length.

Severe respiratory depression in the obstetric patient after intrathecal meperidine or sufentanil

Two cases of severe respiratory depression in the obstetric population are presented. The first occurred after intrathecal injection of a modest dose (50 mg) of meperidine. The second followed intrathecal administration of 10 microg of sufentanil after intravenous fentanyl. These cases illustrate the potential gravity of this complication and highlight the need for caution when giving intrathecal opioid following parenteral opioid administration.

Toluene 2-Monooxygenase-Dependent Growth of Burkholderia cepacia G4/PR1 on Diethyl Ether

Aerobic bacterial growth on aromatic hydrocarbons typically requires oxygenase enzymes, which are known to fortuitously oxidize nongrowth substrates. In this study, we found that oxidation of diethyl ether by toluene 2-monooxygenase supported more rapid growth of Burkholderia cepacia G4/PR1 than did the aromatic substrates n-propylbenzene and o-xylene. The wild-type Burkholderia cepacia G4 failed to grow on diethyl ether. Purified toluene 2-monooxygenase protein components oxidized diethyl ether stoichiometrically to ethanol and acetaldehyde. Butyl methyl ether, diethyl sulfide, and 2-chloroethyl ethyl ether were oxidized by B. cepacia G4/PR1.

Transient radicular irritation after hyperbaric lidocaine spinal anesthesia in parturients

Two cases of transient radicular irritation in pregnant patients are presented. Both cases involve the combination of spinal anesthesia employing hyperbaric 5% lidocaine and a small gauge pencilpoint needle as well as the surgery being performed in the lithotomy position. We recommend that until the potential for lidocaine-induced neuroradicular irritation under these circumstances is evaluated prospectively, hyperbaric lidocaine should not be used for cases in which a small gauge spinal needle is employed and the patient is placed in the lithotomy position.

Multiple chemical exposures: synergism vs. individual exposure levels

Exposure to single chemicals is known to produce congenital malformations in both pregnant animals and humans exposed at sufficiently high intensity. However, real life involves multiple, simultaneous exposures. Using as a database the 43 multiple chemical exposure studies located by Nelson (Teratology 49:33-71; 1994) where synergism was reported, we explored the degree to which such concerns may be realistic from the viewpoint of the current standard developmental toxicity safety evaluation process. Focusing on the assessment of the lowest tested dose of a given agent participating in synergistic activity as compared to its threshold level for eliciting toxicity when administered alone, we found that while the availability of adequate data was limited, all cases, with the possible exception of one, demonstrated synergistic toxic expression only when at least one, and usually both, compounds were used at or above their individual threshold for toxicity. These findings suggest that in animals such phenomena of synergistic chemical interactions are likely to occur only when at least one and more likely both agents are administered at or above their individual threshold for toxicity. To the extent animal studies are predictive of human developmental hazards due to single chemical exposures, available data do not establish multiple chemical exposures as a major human developmental concern.

Trichloroethylene oxidation by purified toluene 2-monooxygenase: products, kinetics, and turnover-dependent inactivation

Trichloroethylene is oxidized by several types of nonspecific bacterial oxygenases. Toluene 2-monooxygenase from Burkholderia cepacia G4 is implicated in trichloroethylene oxidation and is uniquely suggested to be resistant to turnover-dependent inactivation in vivo. In this work, the oxidation of trichloroethylene was studied with purified toluene 2-monooxygenase. All three purified toluene 2-monooxygenase protein components and NADH were required to reconstitute full trichloroethylene oxidation activity in vitro. The apparent Km and Vmax were 12 microM and 37 nmol per min per mg of hydroxylase component, respectively. Ten percent of the full activity was obtained when the small-molecular-weight enzyme component was omitted. The stable oxidation products, accounting for 84% of the trichloroethylene oxidized, were carbon monoxide, formic acid, glyoxylic acid, and covalently modified oxygenase proteins that constituted 12% of the reacted [14C]trichloroethylene. The stable oxidation products may all derive from the unstable intermediate trichloroethylene epoxide that was trapped by reaction with 4-(p-nitrobenzyl)pyridine. Chloral hydrate and dichloroacetic acid were not detected. This finding differs from that with soluble methane monooxygenase and cytochrome P-450 monooxygenase, which produce chloral hydrate. Trichloroethylene-dependent inactivation of toluene 2-monooxygenase activity was observed. All of the protein components were covalently modified during the oxidation of trichloroethylene. The addition of cysteine to reaction mixtures partially protected the enzyme system against inactivation, most notably protecting the NADH-oxidoreductase component. This suggested the participation of diffusible intermediates in the inactivation of the oxidoreductase.

Purification and characterization of toluene 2-monooxygenase from Burkholderia cepacia G4

Recent in vivo studies indicate that ring monooxygenation is a widespread mechanism by which bacteria metabolize aromatic hydrocarbons and obtain carbon and energy. In this study, toluene 2-monooxygenase from Burkholderia (formerly Pseudomonas) cepacia G4 was purified to homogeneity and found to be a three-component enzyme system. The reconstituted enzyme system oxidized toluene to o-cresol and o-cresol to 3-methylcatechol, an important intermediate for growth of the bacterium on toluene. Steady-state kinetic parameters measured for the water-soluble substrate o-cresol were a Km of 0.8 microM and a Vmax of 131 nmol min-1 (mg of hydroxylase protein)-1. The three protein components were (1) a 40 kDa polypeptide containing one FAD and a [2Fe2S] cluster, (2) a 10.4 kDa polypeptide that contained no identifiable metals or organic cofactors, and (3) a 211 kDa alpha 2 beta 2 gamma 2 component containing five to six iron atoms. The 40 kDa flavo-iron-sulfur protein oxidized NADH and transferred electrons to cytochrome c, dyes, and the alpha 2 beta 2 gamma 2 component. It is analogous to other NADH oxidoreductase components found in a wide range of bacterial mono- and dioxygenases. The 10.4 kDa component, added to the other two components and NADH, increased toluene oxidation rates 10-fold. The alpha 2 beta 2 gamma 2 component was indicated to contain the site for toluene binding and hydroxylation by the following observations: (1) tight binding to a toluene affinity column; (2) oxidation of toluene after reduction of the protein with dithionite and adding O2; (3) H2O2-dependent toluene oxidation and catalase activity; and (4) spectroscopic studies of the iron atoms in the component. The alpha 2 beta 2 gamma 2 component had no significant absorbance in the visible region. EPR spectroscopy yielded a signal at g = 16 upon addition of > 2 equiv of electrons per 2 Fe atoms. Taken with the quantitation of five to six iron atoms, the data suggest that the alpha 2 beta 2 gamma 2 component contains two binuclear iron centers. In total, the structural, spectroscopic, and catalytic features of toluene 2-monooxygenase are reminiscent of soluble methane monooxygenase obtained from methanotrophic bacteria. The two enzyme systems also differ in many subtle ways; for example, they oxidize toluene with completely different regiospecificity.

Metabolism of polyhalogenated compounds by a genetically engineered bacterium

The decomposition of organic compounds by bacteria has been studied for almost a century, during which time selective enrichment culture has generated microorganisms capable of metabolizing thousands of organic compounds. But attempts to obtain pure cultures of bacteria that can metabolize highly halogenated compounds, a large and important class of pollutants, have been largely unsuccessful. Polyhalogenated compounds are most frequently metabolized by anaerobic bacteria as a result of reductive dehalogenation reactions, the products of which are typically substrates for bacterial oxygenases. Complete metabolism of polyhalogenated compounds therefore necessitates the sequential use of anaerobic and aerobic bacteria. Here we combine seven genes encoding two multi-component oxygenases in a single strain of Pseudomonas which as a result metabolizes polyhalogenated compounds by means of sequential reductive and oxidative reactions to yield non-toxic products. Cytochrome P450cam monooxygenase reduces polyhalogenated compounds, which are bound at the camphor-binding site, under subatmospheric oxygen tensions. We find that these reduction products are oxidizable substrates for toluene dioxygenase. Perhalogenated chlorofluorocarbons also act as substrates for the genetically engineered strain.

Assessment of the effectiveness of animal developmental toxicity testing for human safety

Evaluations of studies for four well-known human developmental toxicants clearly suggest that a margin of exposure of 1/100th the NOAEL for the most sensitive animal species tested provides adequate safety for the human conceptus. The lowest reported human teratogenic exposures occurred at doses at least one log above the estimated "safe" or acceptable daily exposure based on the most sensitive animal species, that is, 1/100th animal NOAEL. (The MOE ranged from < 1 to 10.). The data and analyses are consistent with the conclusion that, regardless of the type of in utero effect produced in animals, the margin of safety of 100 is likely to protect the human conceptus in utero from developmental perturbation, and it is a scientifically reasonable and conservative default number.

Cosubstrate effects in reductive dehalogenation by Pseudomonas putida G786 expressing cytochrome P-450CAM

Cytochrome P-450CAM was shown to be the primary catalyst mediating reductive dehalogenation of polychlorinated ethanes by Pseudomonas putida G786. Under anaerobic conditions, the enzyme catalyzed reductive elimination reactions in vivo with the substrates hexachloroethane, pentachloroethane, and 1,1,1,2-tetrachlorethane; the products were tetrachloroethylene, trichloroethylene, and 1,1-dichloroethylene, respectively. In vivo reaction rates were determined. No reaction was observed with 1,1,2,2-tetrachloroethane or 1,1,1-trichloroethane. Purified cytochrome P-450CAM was used to measure dissociation constants of polychlorinated ethanes for the enzyme active site. Observed rates and dissociation constants were used to predict the course of a reaction with the three substrates simultaneously. Data obtained from experiments with P. putida G786 generally followed the simulated reaction curves. Oxygen suppressed the reductive dechlorination reactions and, in the case of 1,1,1,2-tetrachlorethane, 2,2,2-trichloroacetaldehyde was formed. Significant rates of reductive dechlorination were observed at 5% oxygen suggesting that these reactions could occur under partially aerobic conditions. These studies highlight the potential to use an aerobic bacterium, P. putida G786, under a range of oxygen tensions to reductively dehalogenate mixed wastes which are only degraded at very low rates by obligately anaerobic bacteria.

Organic peroxides inhibit neutrophil leukotriene B4 biosynthesis

Leukotriene B4, an autacoid metabolite of arachidonic acid produced by polymorphonuclear neutrophils, induces chemokinesis, chemotaxis, and adhesion of these cells at sites of inflammation. Because neutrophil infiltration is a self-limited process, we hypothesized that oxidized lipid products of neutrophil-damaged tissue might inhibit leukotriene B4 biosynthesis, thereby preventing additional neutrophil infiltration and limiting peroxidative tissue damage. Erythrocyte ghosts exposed to a hydrogen peroxide-generating system served as a model of peroxidized tissue in inflammation and inhibited neutrophil leukotriene B4 production by 50% compared with unoxidized ghosts. Organic peroxides, including tert-butylhydroperoxide, peracetic acid, and linoleic hydroperoxide, resembling the product(s) of tissue membrane peroxidation in lipid solubility and catalase resistance, inhibited leukotriene B4 biosynthesis in a dose-dependent manner (50% inhibitory concentration of 3.9 microM compared to 530 microM for H2O2). Biosynthetic steps prior to the 5-lipoxygenase did not appear to be the site of inhibition. Likewise, the step after the 5-lipoxygenase, the leukotriene A4 hydrolase, was not primarily involved. Thus a possible mechanism for controlling the influx of neutrophils and their oxidative damage during inflammation may be inhibition of the 5-lipoxygenase by catalase-resistant lipid peroxides released by tissue membranes.