• Home
  • Petra F G Wolffs
Petra F G Wolffs

Petra F G Wolffs
Maastricht University Medical Center, Maastricht, Netherlands · Medical Microbiology

PhD

About

165
Publications
21,132
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
4,730
Citations
Citations since 2016
77 Research Items
2990 Citations
20162017201820192020202120220100200300400500
20162017201820192020202120220100200300400500
20162017201820192020202120220100200300400500
20162017201820192020202120220100200300400500
Additional affiliations
November 2005 - present
Maastricht Universitair Medisch Centrum
Position
  • Head of the Molecular Microbial Diagnostics unit
November 2005 - present
Maastricht University Medical Center, Maastricht, Netherlands
Position
  • Research Assistant

Publications

Publications (165)
Article
Full-text available
Previous studies have shown high acquisition risks of extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-E) among international travelers visiting antimicrobial resistance (AMR) hotspots. Although antibiotic use and travelers' diarrhea have shown to influence the ESBL-E acquisition risk, it remains largely unknown whether successfu...
Article
Full-text available
It is important i to monitor the transmission and antimicrobial resistance of Neisseria gonorrhoeae (NG). Current surveillance relies on culturing, which frequently fails. Previously, a culture-independent genotyping method was developed based on NG multi-antigen sequence typing (NG-MAST). To determine whether crucial sequence types (STs) are misse...
Article
Full-text available
Objectives We evaluated COVID-19 symptoms, case fatality rate (CFR), and viral load among all Long-Term Care Facility (LTCF) residents and staff in South Limburg, the Netherlands (February 2020-June 2020, wildtype SARS-CoV-2 Wuhan strain). Methods Patient information was gathered via regular channels used to notify the public health services. Ct-v...
Article
Full-text available
There has been a growing body of evidence that the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Delta variant (B.1.617.2) shows enhanced transmissibility and increased viral loads compared to other variants. A recent study has even suggested that respiratory samples from people infected with the Delta variant can harbor up to 1000 t...
Article
Full-text available
Objective: To assess the effect of commonly used contact lens disinfectants against severe acute respiratory syndrome corona virus 2 (SARS-CoV-2). Methods: The efficacy of five disinfectant solutions against SARS-CoV-2 was tested in the presence and absence of contact lenses (CLs). Three types of unused CLs (hard gas permeable, soft hydrogel, an...
Article
Full-text available
Reports of potential treatment failure have raised particular concerns regarding the efficacy of the single dose azithromycin regimen in the treatment of urogenital and anorectal Chlamydia trachomatis (CT) infections. Several factors have been suggested, including heterotypic resistance. Antimicrobial susceptibility testing in CT requires cell cult...
Article
Full-text available
Background Chlamydia trachomatis (CT) is the most common bacterial sexually transmitted infection (STI) worldwide. CT is mainly asymptomatic. Test-and-treat strategies are widely implemented to prevent transmission and complications. Strategies are not without controversy in asymptomatic women and men who have sex with men (MSM). Concerns are emerg...
Article
Full-text available
Aims: Heart failure (HF) represents a clinical syndrome resulting from different aetiologies and degrees of heart diseases. Among these, a key role is played by primary heart muscle disease (cardiomyopathies), which are the combination of multifactorial environmental insults in the presence or absence of a known genetic predisposition. The aim of...
Article
Full-text available
Background Anorectal infections with Chlamydia trachomatis (CT) are common in women visiting STI outpatient clinics. We here evaluated the risk posed by sexual exposure and by alternate anatomical site infection for incident anorectal and urogenital CT. Methods Prospective multicentre cohort study, FemCure. Participants were treated for CT, and af...
Article
Full-text available
Concurrent genital-anal human papillomavirus (HPV) infections may impose an increased anal cancer risk in women with HPV-related genital lesions. High viral load may facilitate genital-anal HPV concurrence. Genital and anal HPV is reduced by a bivalent HPV16/18 vaccine, yet the effect on concurrent genital-anal HPV remains unclear. This study analy...
Article
Full-text available
Purpose: The putative presence of SARS-CoV-2 in ocular specimen puts healthcare workers at risk. We thoroughly examined conjunctival swabs and tear fluid in a large cohort of COVID-19 patients. Methods: A total of 243 symptomatic laboratory-confirmed COVID-19 patients were included in this observational multicenter study. Conjunctival swabs were...
Article
Full-text available
Background Antimicrobial resistance (AMR) is a global public health concern that requires transdisciplinary and bio-social approaches. Despite the continuous calls for a transdisciplinary understanding of this problem, there is still a lack of such studies. While microbiology generates knowledge about the biomedical nature of bacteria, social scien...
Preprint
Full-text available
There has been a growing body of evidence that the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Delta variant (B.1.617.2) shows enhanced transmissibility and increased viral loads compared to other variants. A recent study has even suggested that respiratory samples from people infected with the Delta variant can harbor up to 1000 t...
Conference Paper
Full-text available
Background Anorectal infections with Chlamydia trachomatis (CT) are prevalent in women visiting STI-clinics. In women, azithromycin treatment in anorectal chlamydia is unsuccessful in about 20%, with the potential of subsequent re-infection of the vagina through autoinoculation. We evaluated the risk for incident urogenital CT, by exposure from the...
Conference Paper
Background Nucleic acid amplification tests (NAATs) have revolutionized our ability to diagnose Chlamydia trachomatis (CT). Sometimes, in addition, assessment of CT viability would help to gain more insight in the clinical impact of a positive NAAT. Methods to assess the CT viability have become available in research settings (e.g. viability-PCR; V...
Article
Full-text available
Background The Dutch province of Limburg borders the German district of Heinsberg, which had a large cluster of COVID-19 cases linked to local carnival activities before any cases were reported in the Netherlands. However, Heinsberg was not included as an area reporting local or community transmission per the national case definition at the time. I...
Article
Full-text available
Sexual healthcare aims to reduce HIV and sexually transmitted infections (STIs) by promoting testing and prevention. To better reach men who have sex with men (MSM), additional strategies are needed. Here, we describe development of an intervention, which is part of a broader HIV/STI home-care program, targeted to reach MSM and motivate them to use...
Article
Full-text available
Antimicrobial resistance control programmes often aim to “fix” the behaviour of antibiotic users and prescribers. Such behavioural interventions have been widely criticised in social science literature for being inefficient and too narrow in scope. Drawing on these criticisms, this article analyses how political programmes for fixing antibiotic beh...
Article
Background Chlamydia trachomatis (CT) is routinely diagnosed by nucleic acid amplification tests (NAATs), which are unable to distinguish between nucleic acids from viable and non-viable CT organisms. Objectives We applied our recently developed sensitive PCR (viability PCR) technique to measure viable bacterial CT load and explore associated dete...
Article
Background: Investigation was undertaken to determine the genetic relatedness of Neisseria gonorrhoeae (NG) isolates of young (<25) heterosexuals of a potential outbreak from October 2017 to March 2019 in South-Limburg, the Netherlands. Methods: Data and residual sample material of routine diagnostics were retrieved for outbreak cases (78/81), y...
Article
Background Women are not routinely tested for oropharyngeal Neisseria gonorrhoeae. At present, selective testing based on sexual behaviour or risk groups is advocated by international guidelines. Many oropharyngeal infections are asymptomatic and thus remain undetected, establishing a reservoir for ongoing transmission. Data on effectiveness of rou...
Article
Full-text available
Chlamydia trachomatis (CT) increases its plasmid numbers when stressed, as occurs in clinical trachoma samples. Most CT tests target the plasmid to increase the test sensitivity, but some only target the chromosome. We investigated clinical urogenital samples for total plasmid copy numbers to assess its diagnostic value and intra-bacterial plasmid...
Article
Full-text available
Aim Previous uncontrolled studies indicated a possible benefit of intravenous immunoglobulin (IVIg) in parvovirus B19 (B19V)‐related dilated cardiomyopathy (DCM). This randomized, double‐blind, placebo‐controlled single‐centre trial investigated the benefits of IVIg beyond conventional therapy in idiopathic chronic DCM patients with B19V persistenc...
Article
Full-text available
Background Not all men who have sex with men (MSM) at risk for sexually transmitted infections (STIs) and human immunodeficiency virus (HIV) infection currently receive sexual healthcare. To increase the coverage of high-quality HIV/STI care for MSM, we developed a home-care programme, as extended STI clinic care. This programme included home sampl...
Article
Objectives : Oropharyngeal Chlamydia trachomatis (CT) and especially Neisseria gonorrhoeae (NG) infections are common but few commercial nucleic acid amplification tests (NAATs) specify extragenital samples as intended use. The test characteristics of the cobas®4800 CT/NG assay are evaluated for oropharyngeal swabs. Methods: The technical validatio...
Preprint
Full-text available
Background: The Dutch province of Limburg borders the German district of Heinsberg, which had a large cluster of COVID-19 cases linked to local carnival activities in February, before any cases were reported in the Netherlands. However, Heinsberg was not included as an area reporting local or community transmission per the national case definition...
Article
Full-text available
Background: Repeat Chlamydia trachomatis (CT) infections are common. To better understand the characteristics of patients frequently infected with CT at our sexually transmitted infection (STI) care services, we assessed the differences between patients repeatedly infected with CT and those who repeatedly tested negative. Methods: In this cross-...
Article
Background Neisseria gonorrhoeae (NG) is a common bacterial sexually transmitted infection (STI). Currently, there are limited data on the bacterial load in both men and women, and on both genital and extra-genital sites. Therefore, we quantified NG bacterial load in a large population of women, heterosexual men, and men who have sex with men (MSM)...
Article
Full-text available
Next-generation sequencing (NGS) has instigated the research on the role of the microbiome in health and disease. The compositional nature of such microbiome datasets makes it however challenging to identify those microbial taxa that are truly associated with an intervention or health outcome. Quantitative microbiome profiling overcomes the composi...
Article
Objectives Women attending STI clinics are not routinely tested for oropharyngeal Chlamydia trachomatis (CT) infections. We aimed to assess spontaneous clearance of oropharyngeal CT and cure after antibiotic treatment in women. Methods Women with vaginal or rectal CT (n=560) were recruited at STI clinics in 2016–2017, as part of the FemCure study...
Article
Full-text available
Objectives: Maintenance treatment with macrolide antibiotics has shown to be effective in reducing exacerbations in COPD patients. A major concern with prolonged treatment with antibiotics is the development of bacterial resistance. In this study we determined the effect of azithromycin on the development and acquisition of resistance to macrolide...
Article
We assessed whether patients repeatedly infected with Chlamydia trachomatis (CT) have a lower urogenital or anorectal CT load. A CT positive retest was independently associated with higher vaginal- and higher urine Cq-values (p≤0.001). Partial immunity could play a role in repeat urogenital infections, potentially not in anorectal infections.
Preprint
Full-text available
Objectives Maintenance treatment with macrolide antibiotics has shown to be effective in reducing exacerbations in COPD patients. A major concern with prolonged treatment with antibiotics is the development of bacterial resistance. In this study we determined the effect of azithromycin on the development and acquisition of resistance to macrolides...
Preprint
Full-text available
Objectives: Maintenance treatment with macrolide antibiotics has shown to be effective in reducing exacerbations in COPD patients. A major concern with prolonged treatment with antibiotics is the development of bacterial resistance. In this study we determined the effect of azithromycin on the development and acquisition of resistance to macrolides...
Article
Full-text available
Prospective studies are key study designs when attempting to unravel health mechanisms that are widely applicable. Understanding the internal validity of a prospective study is essential to judge a study’s quality. Moreover, insights in possible sampling bias and the external validity of a prospective study are useful to judge the applicability of...
Article
Full-text available
We assessed whether patients repeatedly infected with Neisseria gonorrhoeae (NG) were different compared to patients repeatedly tested negative, to obtain insight into the characteristics of patients frequently tested and infected with NG. All patients tested for NG (n = 16,662) between January 2011 and July 2018 were included. Multivariable logist...
Article
Objectives Spontaneous clearance of Chlamydia trachomatis (CT) infections can occur between diagnosis and treatment. We followed CT patients to assess clearance using a conventional definition (no total CT-DNA, assessed by routine quantitative PCR methods) and a definition accounting for viability, assessed by viability PCR testing. Methods Three...
Article
Full-text available
Background: Rectal infections with Chlamydia trachomatis (CT) are prevalent in women visiting a sexually transmitted infection outpatient clinic, but it remains unclear what the most effective treatment is. We assessed the effectiveness of doxycycline and azithromycin for the treatment of rectal and vaginal chlamydia in women. Methods: This stud...
Article
Full-text available
One Health (OH) is an increasingly popular approach for addressing antimicrobial resistance (AMR) which is often presented as a shared health concern at the interface of human-animal-environment relations. OH is widely adopted as a framework for collaboration between organisations like the World Health Organisation and the World Organisation for An...
Article
Full-text available
Background: We evaluated the risk of pelvic inflammatory disease (PID), ectopic pregnancy, and infertility in women with a previous Chlamydia trachomatis (CT) diagnosis compared with women who tested negative for CT and CT untested women, considering both targeted and incidental (ie, prescribed for another indication) use of CT-effective antibioti...
Article
Objectives In recent years, studies have demonstrated frequent rectal Chlamydia trachomatis (CT) detection in women, irrespective of reported anal sex or rectal symptoms. However, the clinical relevance and public health implication of rectal CT detection in women remain under debate. Therefore, evaluating CT viability may provide more insight into...
Conference Paper
Full-text available
Background Spontaneous resolution (clearance) of Chlamydia trachomatis (CT) infections can occur between diagnosis by nucleic acid amplification assays (NAAT) and treatment. Moreover, viability polymerase chain reaction (V-PCR) techniques showed that part of non-resolved NAAT positives represent non-viable CT. This may impact clinic policies aiming...
Conference Paper
Full-text available
Background Rectal infections with Chlamydia trachomatis (CT) are prevalent in women visiting a STI outpatient clinic. While azithromycin is the most used treatment, microbiological treatment failure in rectal CT is common and its drivers remain unclear. Methods This study is part of a prospective multicentre cohort study (FemCure). Current analyse...
Conference Paper
Full-text available
Background Swingers, i.e. heterosexual couples who, as a couple, have sex with others within the swingers’ subculture, are a subpopulation at risk for Sexually Transmitted Infections(STI). Human papillomavirus (HPV) has proven to be highly prevalent in female swingers (unpublished data). The aim of this study is to assess how the different HPV geno...
Conference Paper
Full-text available
Background Despite public-health efforts, men who have sex with men (MSM) are still not sufficiently reached with current HIV/STI care. We developed a regional MSM home-care program, used by public-health STI care, hospital HIV care, and general practitioners. The program combines home-based self-sampling testing for HIV, syphilis, chlamydia and go...
Conference Paper
Full-text available
Background Surveillance of Neisseria gonorrhoeae (NG) is important to monitor antimicrobial resistance and detect outbreaks but is limited by the low NG culture success rate. Recently, we developed a culture-free NG multi-antigen sequence typing (NG-MAST) method. In 2018, an increase of 155% of genital NG cases in heterosexual men and women younger...
Conference Paper
Full-text available
Background The bacterial load of Chlamydia trachomatis (CT) infected individuals may indicate the likelihood of further transmission and development of sequelae. This is the first and largest study to date providing results of a complete overview of the bacterial CT-load of genital and extra-genital samples and its associations with Neisseria gonor...
Conference Paper
Full-text available
Background Diagnosing an infection with Treponema pallidum, the causative agent of syphilis, is routinely based on serology. STD clinics routinely screen those with high-risk sexual behaviour, e.g. MSM, for syphilis. In case of an ulcus, swabs taken from the ulcer can be tested for T. pallidum by PCR. Here, we assessed the added value of PCR next t...
Conference Paper
Full-text available
Background The participation of women in prospective sexual health research is key to understanding mechanisms of their health, and best practices need to be shared. We here evaluate participation, retention, and associated factors, of women in a multicenter prospective cohort (FemCure) providing insights in internal and external validity of this p...
Conference Paper
Full-text available
Background Symptoms have been associated with Chlamydia trachomatis (CT) infections in culture-based studies, in contrast to studies based on nucleic acid amplification tests (NAAT). This may be because NAAT also detect non-viable bacteria. As culturing techniques are insensitive, we developed a sensitive polymerase chain reaction (V-PCR) technique...
Conference Paper
Full-text available
Background The bacterial load of Chlamydia trachomatis (CT) infected individuals may indicate the likelihood of further transmission and development of sequelae. For the first time, we compared the urogenital CT-load of men and women diagnosed by general practitioners (GPs), hospital physicians and the STI clinic. Methods All urogenital nucleic ac...
Conference Paper
Full-text available
Background In spite of excellent analytical sensitivity, NAAT assays for Chlamydia trachomatis (CT) do not have a 100% detection probability (DP), especially at low concentrations of CT. This might especially impact test results after treatment, when CT concentrations are expected to be very low. The aim of this study was to use repeat testing to i...
Conference Paper
Full-text available
Background Recently it was proposed that patients repeatedly infected with Chlamydia trachomatis(CT) or Neisseria gonorrhoeae(NG), so called core groups, likely have high impact on circulating STIs within the population. To substantiate such proposition, more information is needed on (1) whether the characteristics of those single infected patients...
Conference Paper
Full-text available
Background Current routine diagnostic methods for the detection of Chlamydia trachomatis (CT) do not provide information on CT viability. Previously, detection of messenger-RNA (mRNA) has been utilized as a marker for bacterial viability, as mRNA molecules are generally short-lived (half-life of minutes). However, only one study evaluated CT mRNA h...
Conference Paper
Full-text available
Background When Chlamydia trachomatis (CT) is detected after adequate treatment, this may reflect treatment failure or re-infection due to sexual re-exposure. For sexual exposure, researchers rely on self-reported data. Biomarkers such as Y-chromosomal DNA (Y-DNA) from vaginal and rectal samples may be used to support the validity of the self-repor...
Conference Paper
Full-text available
Background Surveillance of Neisseria gonorrhoeae (NG) is important to monitor NG transmission and dissemination of resistant strains. A widely used surveillance method is NG multi-antigen sequence typing (NG-MAST) which relies on genotyping of cultured strains while culture frequently fails. Recently, we developed a culture-free genotyping method w...
Conference Paper
Full-text available
Background Swingers are at high risk for acquiring sexual transmitted infections (STI). The prevalence of human papillomavirus (HPV) in this population is unknown. This information is necessary to assess whether this high risk population should be included in the HPV prevention strategies. In this case-control study the prevalence of HPV in female...
Article
Objectives Most international STI guidelines recommend Chlamydia trachomatis anorectal testing in women after self-reported sexual exposure or symptoms in women. However, it has been shown that the prevalence of anorectal C. trachomatis is as high (7%–17 %) in women who do not report anorectal intercourse (AI) as in women who do. This study assesse...
Article
Full-text available
Background: The bacterial load of Chlamydia trachomatis (CT) is assumed to play a role in transmission and sequelae. We assessed urogenital CT cycle quantification (Cq) values, as an indicator for CT load, of men and women diagnosed by general practitioners (GPs), hospital physicians and the STI clinic. Methods: Urogenital CT-positive samples (n...