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Dive into the research topics where Tjip S. van der Werf is active.

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Featured researches published by Tjip S. van der Werf.


PLOS Medicine | 2012

Multidrug Resistant Pulmonary Tuberculosis Treatment Regimens and Patient Outcomes: An Individual Patient Data Meta-analysis of 9,153 Patients

Shama D. Ahuja; David Ashkin; Monika Avendano; Rita Banerjee; Melissa Bauer; Jamie N. Bayona; Mercedes C. Becerra; Andrea Benedetti; Marcos Burgos; Rosella Centis; Eward D. Chan; Chen-Yuan Chiang; Helen Cox; Lia D'Ambrosio; Kathy DeRiemer; Nguyen Huy Dung; Donald A. Enarson; Dennis Falzon; Katherine Flanagan; Jennifer Flood; Maria L. Garcia-Garcia; Neel R. Gandhi; Reuben Granich; Maria Graciela Hollm-Delgado; Timothy H. Holtz; Michael D. Iseman; Leah G. Jarlsberg; Salmaan Keshavjee; Hye-Ryoun Kim; Won-Jung Koh

Dick Menzies and colleagues report findings from a collaborative, individual patient-level meta-analysis of treatment outcomes among patients with multidrug-resistant tuberculosis.


The Lancet | 1999

Mycobacterium ulcerans infection

Tjip S. van der Werf; Winette T. A. van der Graaf; Jordan W Tappero; Kingsley Asiedu

After tuberculosis and leprosy, Buruli-ulcer disease (caused by infection with Mycobacterium ulcerans) is the third most common mycobacterial disease in immunocompetent people. Countries in which the disease is endemic have been identified, predominantly in areas of tropical rain forest; the emergence of Buruli-ulcer disease in West African countries over the past decade has been dramatic. Current evidence suggests that the infection is transmitted through abraded skin or mild traumatic injuries after contact with contaminated water, soil, or vegetation; there is one unconfirmed preliminary report on possible transmission by insects. The clinical picture ranges from a painless nodule to large, undermined ulcerative lesions that heal spontaneously but slowly. Most patients are children. The disease is accompanied by remarkably few systemic symptoms, but occasionally secondary infections resulting in sepsis or tetanus cause severe systemic disease and death. Extensive scarring can lead to contractures of the limbs, blindness, and other adverse sequelae, which impose a substantial health and economic burden. Treatment is still primarily surgical, and includes excision, skin grafting, or both. Although BCG has a mild but significant protective effect, new vaccine developments directed at the toxins produced by M. ulcerans are warranted. In West Africa, affected populations are underprivileged, and the economic burden imposed by Buruli-ulcer disease is daunting. Combined efforts to improve treatment, prevention, control, and research strategies (overseen by the WHO and funded by international relief agencies) are urgently needed.


JAMA | 2013

Effect of Azithromycin Maintenance Treatment on Infectious Exacerbations Among Patients With Non-Cystic Fibrosis Bronchiectasis The BAT Randomized Controlled Trial

Josje Altenburg; Casper S. de Graaff; Ymkje Stienstra; Jacobus H. Sloos; Eric H. J. van Haren; Ralph J. H. Koppers; Tjip S. van der Werf; Wim G. Boersma

IMPORTANCE Macrolide antibiotics have been shown beneficial in cystic fibrosis (CF) and diffuse panbronchiolitis, and earlier findings also suggest a benefit in non-CF bronchiectasis. OBJECTIVE To determine the efficacy of macrolide maintenance treatment for adults with non-CF bronchiectasis. DESIGN, SETTING, AND PARTICIPANTS The BAT (Bronchiectasis and Long-term Azithromycin Treatment) study, a randomized, double-blind, placebo-controlled trial conducted between April 2008 and September 2010 in 14 hospitals in The Netherlands among 83 outpatients with non-CF bronchiectasis and 3 or more lower respiratory tract infections in the preceding year. INTERVENTIONS Azithromycin (250 mg daily) or placebo for 12 months. MAIN OUTCOME MEASURES Number of infectious exacerbations during 12 months of treatment. Secondary end points included lung function, sputum bacteriology, inflammatory markers, adverse effects, symptom scores, and quality of life. RESULTS Forty-three participants (52%) received azithromycin and 40 (48%) received placebo and were included in the modified intention-to-treat analysis. At end of study, the median number of exacerbations in the azithromycin group was 0 (interquartile range [IQR], 0-1), compared with 2 (IQR, 1-3) in the placebo group (P < .001). Thirty-two (80%) placebo-treated vs 20 (46%) azithromycin-treated individuals had at least 1 exacerbation (hazard ratio, 0.29 [95% CI, 0.16-0.51]). In a mixed-model analysis, change in forced expiratory volume in the first second of expiration (percent of predicted) over time differed between groups (F1,78.8 = 4.085, P = .047), with an increase of 1.03% per 3 months in the azithromycin group and a decrease of 0.10% per 3 months in the placebo group. Gastrointestinal adverse effects occurred in 40% of patients in the azithromycin group and in 5% in the placebo group (relative risk, 7.44 [95% CI, 0.97-56.88] for abdominal pain and 8.36 [95% CI, 1.10-63.15] for diarrhea) but without need for discontinuation of study treatment. A macrolide resistance rate of 88% was noted in azithromycin-treated individuals, compared with 26% in the placebo group. CONCLUSIONS AND RELEVANCE Among adults with non-CF bronchiectasis, the daily use of azithromycin for 12 months compared with placebo resulted in a lower rate of infectious exacerbations. This could result in better quality of life and might influence survival, although effects on antibiotic resistance need to be considered. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00415350.


The Lancet | 2010

Antimicrobial treatment for early, limited Mycobacterium ulcerans infection: a randomised controlled trial

Willemien A. Nienhuis; Ymkje Stienstra; William A. Thompson; Peter C. Awuah; K. Mohammed Abass; Wilson Tuah; Nana Yaa Awua-Boateng; Edwin Ampadu; Vera Siegmund; Jan P. Schouten; Ohene Adjei; Gisela Bretzel; Tjip S. van der Werf

BACKGROUND Surgical debridement was the standard treatment for Mycobacterium ulcerans infection (Buruli ulcer disease) until WHO issued provisional guidelines in 2004 recommending treatment with antimicrobial drugs (streptomycin and rifampicin) in addition to surgery. These recommendations were based on observational studies and a small pilot study with microbiological endpoints. We investigated the efficacy of two regimens of antimicrobial treatment in early-stage M ulcerans infection. METHODS In this parallel, open-label, randomised trial undertaken in two sites in Ghana, patients were eligible for enrolment if they were aged 5 years or older and had early (duration <6 months), limited (cross-sectional diameter <10 cm), M ulcerans infection confirmed by dry-reagent-based PCR. Eligible patients were randomly assigned to receive intramuscular streptomycin (15 mg/kg once daily) and oral rifampicin (10 mg/kg once daily) for 8 weeks (8-week streptomycin group; n=76) or streptomycin and rifampicin for 4 weeks followed by rifampicin and clarithromycin (7.5 mg/kg once daily), both orally, for 4 weeks (4-week streptomycin plus 4-week clarithromycin group; n=75). Randomisation was done by computer-generated minimisation for study site and type of lesion (ulceration or no ulceration). The randomly assigned allocation was sent from a central site by cell-phone text message to the study coordinator. The primary endpoint was lesion healing at 1 year after the start of treatment without lesion recurrence or extensive surgical debridement. Analysis was by intention-to-treat. This trial is registered with ClinicalTrials.gov, number NCT00321178. FINDINGS Four patients were lost to follow-up (8-week streptomycin, one; 4-week streptomycin plus 4-week clarithromycin, three). Since these four participants had healed lesions at their last assessment, they were included in the analysis for the primary endpoint. 73 (96%) participants in the 8-week streptomycin group and 68 (91%) in the 4-week streptomycin plus 4-week clarithromycin group had healed lesions at 1 year (odds ratio 2.49, 95% CI 0.66 to infinity; p=0.16, one-sided Fishers exact test). No participants had lesion recurrence at 1 year. Three participants had vestibulotoxic events (8-week streptomycin, one; 4-week streptomycin plus 4-week clarithromycin, two). One participant developed an injection abscess and two participants developed an abscess close to the initial lesion, which was incised and drained (all three participants were in the 4-week streptomycin plus 4-week clarithromycin group). INTERPRETATION Antimycobacterial treatment for M ulcerans infection is effective in early, limited disease. 4 weeks of streptomycin and rifampicin followed by 4 weeks of rifampicin and clarithromycin has similar efficacy to 8 weeks of streptomycin and rifampicin; however, the number of injections of streptomycin can be reduced by switching to oral clarithromycin after 4 weeks. FUNDING European Union (EU FP6 2003-INCO-Dev2-015476) and Buruli Ulcer Groningen Foundation.


American Journal of Respiratory and Critical Care Medicine | 2010

Efficacy of corticosteroids in community-acquired pneumonia - a randomized double blinded clinical trial

Dominic Snijders; Johannes Marlene Daniels; Casper S. de Graaff; Tjip S. van der Werf; Wim Boersma

RATIONALE Some studies have shown a beneficial effect of corticosteroids in patients with community-acquired pneumonia (CAP), possibly by diminishing local and systemic antiinflammatory host response. OBJECTIVES To assess the efficacy of adjunctive prednisolone treatment in patients hospitalized with CAP. METHODS Hospitalized patients, clinically and radiologically diagnosed with CAP using standard clinical and radiological criteria, were randomized to receive 40 mg prednisolone for 7 days or placebo, along with antibiotics. Primary outcome was clinical cure at Day 7. Secondary outcomes were clinical cure at Day 30, length of stay, time to clinical stability, defervescence, and C-reactive protein. Disease severity was scored using CURB-65 (a severity index for community-acquired pneumonia evaluating Confusion, blood Urea nitrogen, Respiratory rate, Blood pressure, and age 65 or older) and Pneumonia Severity Index. MEASUREMENTS AND MAIN RESULTS We enrolled 213 patients. Fifty-four (25.4%) patients had a CURB-65 score greater than 2, and 93 (43.7%) patients were in Pneumonia Severity Index class IV-V. Clinical cure at Days 7 and 30 was 84/104 (80.8%) and 69/104 (66.3%) in the prednisolone group and 93/109 (85.3%) and 84/109 (77.1%) in the placebo group (P = 0.38 and P = 0.08). Patients on prednisolone had faster defervescence and faster decline in serum C-reactive protein levels compared with placebo. Subanalysis of patients with severe pneumonia did not show differences in clinical outcome. Late failure (>72 h after admittance) was more common in the prednisolone group (20 patients, 19.2%) than in the placebo group (10 patients, 6.4%; P = 0.04). Adverse events were few and not different between the two groups. CONCLUSIONS Prednisolone (at 40 mg) once daily for a week does not improve outcome in hospitalized patients with CAP. A benefit in more severely ill patients cannot be excluded. Because of its association with increased late failure and lack of efficacy prednisolone should not be recommended as routine adjunctive treatment in CAP.


Bulletin of The World Health Organization | 2005

Mycobacterium ulcerans disease

Tjip S. van der Werf; Ymkje Stienstra; R. Christian Johnson; Richard Phillips; Ohene Adjei; Bernhard Fleischer; Mark Wansbrough-Jones; Paul D. R. Johnson; Françoise Portaels; Winette T. A. van der Graaf; Kingsley Asiedu

Mycobacterium ulcerans disease (Buruli ulcer) is an important health problem in several west African countries. It is prevalent in scattered foci around the world, predominantly in riverine areas with a humid, hot climate. We review the epidemiology, bacteriology, transmission, immunology, pathology, diagnosis and treatment of infections. M. ulcerans is an ubiquitous micro-organism and is harboured by fish, snails, and water insects. The mode of transmission is unknown. Lesions are most common on exposed parts of the body, particularly on the limbs. Spontaneous healing may occur. Many patients in endemic areas present late with advanced, severe lesions. BCG vaccination yields a limited, relatively short-lived, immune protection. Recommended treatment consists of surgical debridement, followed by skin grafting if necessary. Many patients have functional limitations after healing. Better understanding of disease transmission and pathogenesis is needed for improved control and prevention of Buruli ulcer.


Emerging Infectious Diseases | 2003

Histopathologic features of Mycobacterium ulcerans infection.

Jeannette Guarner; Jeanine Bartlett; Ellen A. Spotts Whitney; Pratima L. Raghunathan; Ymkje Stienstra; Kwame Asamoa; Samuel Etuaful; Erasmus Klutse; Eric Quarshie; Tjip S. van der Werf; Winette T. A. van der Graaf; C. Harold King; David A. Ashford

Because of the emergence of Buruli ulcer disease, the World Health Organization launched a Global Buruli Ulcer Initiative in 1998. This indolent skin infection is caused by Mycobacterium ulcerans. During a study of risk factors for the disease in Ghana, adequate excisional skin-biopsy specimens were obtained from 124 clinically suspicious lesions. Buruli ulcer disease was diagnosed in 78 lesions since acid-fast bacilli (AFB) were found by histopathologic examination. Lesions with other diagnoses included filariasis (3 cases), zygomycosis (2 cases), ulcerative squamous cell carcinomas (2 cases), keratin cyst (1 case), and lymph node (1 case). Thirty-seven specimens that did not show AFB were considered suspected Buruli ulcer disease cases. Necrosis of subcutaneous tissues and dermal collagen were found more frequently in AFB-positive specimens compared with specimens from suspected case-patients (p<0.001). Defining histologic criteria for a diagnosis of Buruli ulcer disease is of clinical and public health importance since it would allow earlier treatment, leading to less deforming sequelae.


Clinical Infectious Diseases | 2005

Risk factors for Buruli ulcer disease (Mycobacterium ulcerans infection) : Results from a case-control study in Ghana

Pratima L. Raghunathan; Ellen A. Whitney; Kwame Asamoa; Ymkje Stienstra; Thomas H. Taylor; George K. Amofah; David Ofori-Adjei; Karen M. Dobos; Jeannette Guarner; Stacey Martin; Sonal Pathak; Erasmus Klutse; Samuel Etuaful; Winette T. A. van der Graaf; Tjip S. van der Werf; Ch King; Jordan W. Tappero; David A. Ashford

BACKGROUND Morbidity due to Buruli ulcer disease (BUD), a cutaneous infection caused by Mycobacterium ulcerans, has been increasingly recognized in rural West Africa. The source and mode of transmission remain unknown. METHODS To identify BUD risk factors, we conducted a case-control study in 3 BUD-endemic districts in Ghana. We enrolled case patients with clinically diagnosed BUD and obtained skin biopsy specimens. M. ulcerans infection was confirmed by at least 1 of the following diagnostic methods: histopathologic analysis, culture, polymerase chain reaction, and Ziehl-Neelsen staining of a lesion smear. We compared characteristics of case patients with confirmed BUD with those of age- and community-matched control subjects using conditional logistic regression analysis. RESULTS Among 121 case patients with confirmed BUD, leg lesions (49%) or arm lesions (36%) were common. Male case patients were significantly more likely than female case patients to have lesions on the trunk (25% vs. 6%; P = .009). Multivariable modeling among 116 matched case-control pairs identified wading in a river as a risk factor for BUD (odds ratio [OR], 2.69; 95% confidence interval [CI], 1.27-5.68; P = .0096). Wearing a shirt while farming (OR, 0.27; 95% CI, 0.11-0.70; P = .0071), sharing indoor living space with livestock (OR, 0.36; 95% CI, 0.15-0.86; P = .022), and bathing with toilet soap (OR, 0.41; 95% CI, 0.19-0.90; P = .026) appeared to be protective. BUD was not significantly associated with penetrating injuries (P = .14), insect bites near water bodies (P = .84), bacille Calmette-Guerin vaccination (P = .33), or human immunodeficiency virus infection (P = .99). CONCLUSIONS BUD is an environmentally acquired infection strongly associated with exposure to river areas. Exposed skin may facilitate transmission. Until transmission is better defined, control strategies in BUD-endemic areas could include covering exposed skin.


British Journal of Nutrition | 2010

Association between Faecalibacterium prausnitzii and dietary fibre in colonic fermentation in healthy human subjects

Robin F. J. Benus; Tjip S. van der Werf; Gjalt W. Welling; Patricia A. Judd; Moira A. Taylor; Hermie J. M. Harmsen; Kevin Whelan

The intestinal microbiota are a complex ecosystem influencing the immunoregulation of the human host, providing protection from colonising pathogens and producing SCFA as the main energy source of colonocytes. Our objective was to investigate the effect of dietary fibre exclusion and supplementation on the intestinal microbiota and SCFA concentrations. Faecal samples were obtained from healthy volunteers before and after two 14 d periods of consuming formulated diets devoid or supplemented with fibre (14 g/l). The faecal microbiota were analysed using fluorescent in situ hybridisation and SCFA were measured using GLC. There were large and statistically significant reductions in the numbers of the Faecalibacterium prausnitzii (P < or = 0.01) and Roseburia spp. (P < or = 0.01) groups during both the fibre-free and fibre-supplemented diets. Significant and strong positive correlations between the proportion of F. prausnitzii and the proportion of butyrate during both baseline normal diets were found (pre-fibre free r 0.881, P = 0.001; pre-fibre supplemented r 0.844, P = 0.002). A significant correlation was also found between the proportional reduction in F. prausnitzii and the proportional reduction in faecal butyrate during both the fibre-free (r 0.806; P = 0.005) and the fibre-supplemented diet (r 0.749; P = 0.013). These findings may contribute to the understanding of the association between fibre, microbiota and fermentation in health, during enteral nutrition and in disease states such as Crohns disease.


Critical Care | 2005

Quality of interhospital transport of critically ill patients: a prospective audit

Jack Ligtenberg; L Gert Arnold; Ymkje Stienstra; Tjip S. van der Werf; John H.J.M. Meertens; Jaap Tulleken; Jan G. Zijlstra

IntroductionThe aim of transferring a critically ill patient to the intensive care unit (ICU) of a tertiary referral centre is to improve prognosis. The transport itself must be as safe as possible and should not pose additional risks. We performed a prospective audit of the quality of interhospital transports to our university hospital-based medical ICU.MethodsTransfers were undertaken using standard ambulances. On departure and immediately after arrival, the following data were collected: blood pressure, heart rate, body temperature, oxygen saturation, arterial blood gas analysis, serum lactic acid, plasma haemoglobin concentration, blood glucose, mechanical ventilation settings, use of vasopressor/inotropic drugs, and presence of venous and arterial catheters. Ambulance personnel completed forms describing haemodynamic and ventilatory data during transport. Data were collected by our research nurse and analyzed.ResultsA total of 100 consecutive transfers of ICU patients over a 14-month period were evaluated. Sixty-five per cent of patients were mechanically ventilated; 38% were on vasoactive drugs. Thirty-seven per cent exhibited an increased number of vital variables beyond predefined thresholds after transport compared with before transport; 34% had an equal number; and 29% had a lower number of vital variables beyond thresholds after transport. The distance of transport did not correlate with the condition on arrival. Six patients died within 24 hours after arrival; vital variables in these patients were not significantly different from those in patients who survived the first 24 hours. ICU mortality was 27%. Adverse events occurred in 34% of transfers; in 50% of these transports, pretransport recommendations given by the intensivist of our ICU were ignored. Approximately 30% of events may be attributed to technical problems.ConclusionOn aggregate, the quality of transport in our catchment area carried out using standard ambulances appeared to be satisfactory. However, examination of the data in greater detail revealed a number of preventable events. Further improvement must be achieved by better communication between referring and receiving hospitals, and by strict adherence to checklists and to published protocols. Patients transported between ICUs are still critically ill and should be treated as such.

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