H. Verbakel - Academia.edu (original) (raw)
Papers by H. Verbakel
and enzyme-linked immunoassay. henselae-based indirect fluorescence assay serology: evaluation of... more and enzyme-linked immunoassay. henselae-based indirect fluorescence assay serology: evaluation of Bartonella Pitfalls and fallacies of cat scratch disease
Tumour Virus Research, 2021
Concurrent genital-anal human papillomavirus (HPV) infections may impose an increased anal cancer... more 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 analyzed viral load in concurrent genital-anal HPV infections, relative to genital-only and anal-only HPV infections and the impact of vaccination in young women. We included 1074 women, who provided both genital and anal swabs. HPV detection and genotyping was performed using the SPF10-DEIA-LiPA25. HPV copy numbers were measured with type-specific qPCRs and corrected for cellular content to obtain the viral load. Concurrent genital-anal HPV often had significantly higher genital viral load (0.09–371 c/cell) than genital-only HPV (3.17E-04-15.9 c/cell, p < 0.0001 to p < 0.05). Moreover, nearly all concurrent genital-anal HPV types had higher genital copy numbers per PCR reaction (157-416E04 c/rxn) than anal copy numbers (0.90–884E01 c/rxn, p < 0.0001 to p < 0.001). Vaccinated women had significantly less infections with HPV16/18 vaccine-types (2.8% vs 13.7%, p < 0.0001) and HPV31/35/45 cross-protective types (7.4% vs 21.1%, p < 0.0001) than unvaccinated women. In conclusion, particularly high genital viral load is found in concurrent genital-anal HPV infections, which are effectively reduced by vaccination.
Clinical Infectious Diseases, 2020
Background Human papillomavirus (HPV) vaccination programs achieve substantial population-level i... more Background Human papillomavirus (HPV) vaccination programs achieve substantial population-level impact, with effects extending beyond protection of vaccinated individuals. We assessed trends in HPV prevalence up to 8 years postvaccination among men and women in the Netherlands, where bivalent HPV vaccination, targeting HPV types 16/18, has been offered to (pre)adolescent girls since 2009 with moderate vaccination coverage. Methods We used data from the PASSYON study, a survey initiated in 2009 (prevaccination) and repeated biennially among 16- to 24-year-old visitors of sexual health centers. We studied genital HPV positivity from 2009 to 2017 among women, heterosexual men, and unvaccinated women using Poisson generalized estimating equation models, adjusted for individual- and population-level confounders. Trends were studied for 25 HPV types detected by the SPF10-LiPA25 platform. Results A total of 6354 women (64.7% self-reported unvaccinated) and 2414 heterosexual men were includ...
Journal of Clinical Microbiology, 1999
Repetitive sequence-based (Rep)-PCR genotyping as described here is based on the presence of homo... more Repetitive sequence-based (Rep)-PCR genotyping as described here is based on the presence of homologues of Mycoplasma pneumoniae repeat-like elements in Staphylococcus . In this study we comparatively evaluated the usefulness of rep-PCR typing with two sets of well-defined collections of Staphylococcus aureus strains. Rep-PCR analysis of the first collection of S. aureus strains ( n = 59) and one Staphylococcus intermedius strain showed 14 different rep-PCR patterns, with each pattern harboring 6 to 15 DNA fragments. The discriminatory power of rep-PCR typing compared well to those of arbitrarily primed PCR (average of 20 types) and pulsed-field gel electrophoresis (11 types). S. aureus strain collection I comprised four outbreak-related groups of isolates. The isolates in only one group were found to have identical rep-PCR profiles. However, in an analysis of isolates from three additional independent local outbreaks ( n for outbreaks 1 and 2 = 5, n for outbreak 3 = 12), identical ...
Journal of Clinical Microbiology, 1997
The diagnostic value of the detection of immunoglobulin G (IgG) and IgM by Bartonella henselae-ba... more The diagnostic value of the detection of immunoglobulin G (IgG) and IgM by Bartonella henselae-based indirect fluorescence assay (IFA) and enzyme-linked immunoassay (EIA) for the diagnosis of cat scratch disease (CSD) was evaluated. The IFA was performed either with B. henselae that was cocultivated for a few hours with Vero cells or with noncocultivated B. henselae as the antigen. Additionally, the performance of a Bartonella PCR hybridization assay based on the 16S rRNA gene was determined and compared with those of the serologic assays. The study group consisted of 45 patients suspected of suffering from CSD by fulfilling one or more of the classical criteria. The specificities of the immunoassays were set at > or = 95% by analysis of sera from 60 healthy blood donors. It is shown that the sensitivities of the IgG assays are very low (40.9% for the IFA with noncocultivated B. henselae as antigen) and that those of the IgM assays are higher (71.4% for the EIA) for patients who ...
The Journal of infectious diseases, Jan 4, 2018
Observational postmarketing studies are important to assess vaccine effectiveness (VE). We estima... more Observational postmarketing studies are important to assess vaccine effectiveness (VE). We estimated VE from the bivalent human papillomavirus (HPV) vaccine against HPV positivity of vaccine and nonvaccine types in a high-risk population. We included all vaccine-eligible women from the PASSYON study, a biennial cross-sectional survey in Dutch sexually transmitted infection clinics. Vaginal swabs were analyzed using a polymerase chain reaction-based assay (SPF10-LiPA25) able to detect the 12 high-risk HPV (hrHPV) types 16/18/31/33/35/39/45/51/52/56/58/59. We compared hrHPV positivity between self-reported vaccinated (≥1 dose) and unvaccinated women, and estimated VE by a logistic mixed model. We included 1087 women of which 53% were hrHPV positive and 60% reported to be vaccinated. The adjusted pooled VE against HPV-16/18 was 89.9% (81.7%-94.4%). Moreover, we calculated significant VE against nonvaccine types HPV-45 (91%), HPV-35 (57%), HPV-31 (50%), and HPV-52 (37%). Among women who...
Journal of Infection, 2017
Condylomata acuminata; Warts; Vaccination; Human papillomavirus vaccine, L1 type 16, 18; Preventi... more Condylomata acuminata; Warts; Vaccination; Human papillomavirus vaccine, L1 type 16, 18; Prevention & control Methods: We included all vaccine-eligible women from the PASSYON study, a biennial crosssectional study among 16-to 24-year-old sexually transmitted infection (STI) clinic attendants. Vaginal self-swabs were analyzed for type specific HPV and AGW were diagnosed at the STIclinic. Prevalence of HPV-6 and/or HPV-11 and AGW were compared between self-reported vaccinated and unvaccinated women by log-binomial regression analysis, adjusted for demographics and risk behavior. Results: Of the 1198 women included, 56% reported to be vaccinated at least once. Relative to unvaccinated women, the adjusted prevalence ratio (PR) for HPV-6/11 was 1.03 (95% confidence interval [CI] 0.74e1.43) for women vaccinated at least once. The crude PR for AGW was 0.67 (95% CI 0.22e2.07) for women vaccinated at least once. Adjustment did not change these results. Conclusions: We observed no cross-protective effect of the bivalent vaccine on genital HPV-6/ 11 positivity and a non-significant partially protective effect on AGW.
This study was aimed at contributing to finding the source of a epidemic of Legionnaire&a... more This study was aimed at contributing to finding the source of a epidemic of Legionnaire&amp;amp;amp;#39;s disease (LD) in visitors of the Westfriese Flora 1999 (West-Frisian Flower-show). The Westfriese Flora is a yearly flower exhibition combined with an agricultural and consumer products fair. The study targeted all persons without LD who had been working on the Westfriese Flora as volunteer, employee
Journal of Clinical Microbiology, 2002
European Journal of Clinical Microbiology & Infectious Diseases, 2012
Legionnaires&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; disease (LD) is an acute pneumonia ... more Legionnaires&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; disease (LD) is an acute pneumonia caused by the inhalation or aspiration of aerosols contaminated with the Legionella bacteria. In the Netherlands, around 300 LD cases per year were reported between 2000 and 2008, but in 2009, the number dropped to 251, which was the lowest number in the previous 5 years of surveillance. We investigated if this decrease could be explained by the number of performed Legionella diagnostic tests in this year. We analyzed the number of tests performed between 2007 and 2009 in three large microbiological laboratories in different geographical regions in the Netherlands. Our data showed that there was no decrease in the number of patients for whom a diagnostic test for Legionella was performed in this period. These results are not in line with our hypothesis that the decrease in reported Legionella pneumonia patients in 2009 would be due to a decrease in patients for whom a diagnostic test was performed. We conclude that it is more likely that other factors such as the influence of weather patterns might explain the sudden drop in reported Legionella pneumonia patients in 2009 compared to the previous years, and it would be interesting to investigate this for the period described.
Journal of Medical Microbiology, 2010
Bartonella henselae serology
This study reports the development and evaluation of an internally controlled real-time PCR targe... more This study reports the development and evaluation of an internally controlled real-time PCR targeting the ospA gene for detection of Borrelia burgdorferi sensu stricto, Borrelia garinii, Borrelia afzelii and Borrelia valaisiana. DNA was extracted using QIAamp DNA Blood Mini kit columns. DNA from 33 B. burgdorferi sensu lato strains reacted in the assay, whereas no reactivity was observed with DNA from four relapsing fever Borrelia spp., 11 unrelated spirochaetes, and 31 unrelated microorganisms. The quantitative sensitivity of the assay was 1-10 fg of Borrelia DNA and one to five cultured Borrelia spirochaetes. Cerebrospinal fluid (CSF) specimens from 70 patients sent for routine testing for neuroborreliosis, and three CSF specimens containing B. garinii were also tested. Positive PCR results were obtained with all three culture-confirmed neuroborreliosis specimens, five of ten neuroborreliosis specimens with specific antibodies in CSF and pleocytosis, none of nine specimens from possible cases of early neuroborreliosis (antibodies in serum, CSF pleocytosis, no antibodies in CSF), one of 15 specimens from patients with active or past Lyme disease with neurological signs (antibodies in serum, no pleocytosis or antibodies in CSF), and none of 36 specimens from patients without Lyme borreliosis (no antibodies in serum or CSF). Overall, the real-time PCR assay enabled sensitive and specific detection of all B. burgdorferi sensu lato species tested. The PCR had a sensitivity of 50% in patients with neuroborreliosis. The main diagnostic role of the assay could be to confirm neuroborreliosis in patients for whom the diagnosis is doubtful.
Journal of Medical Microbiology, 2008
Journal of Clinical Microbiology, 2002
European Journal of Clinical Microbiology and Infections Diseases, 2001
Recent studies have suggested that Chlamydia pneumoniae infection is a risk factor for abdominal ... more Recent studies have suggested that Chlamydia pneumoniae infection is a risk factor for abdominal aortic aneurysm. This study explores the presence of Chlamydia pneumoniae DNA in buffy-coat samples of control subjects and of patients with abdominal aortic aneurysm. The seroepidemiological association between abdominal aortic aneurysm and Chlamydia pneumoniae was also investigated. Buffy-coat samples and serum specimens were obtained from 88 patients and 88 control subjects. Detection of Chlamydia pneumoniae DNA in buffy-coat samples and measurement of IgG antibodies to Chlamydia pneumoniae in serum specimens were performed by polymerase chain reaction and microimmunofluorescence, respectively. Chlamydia pneumoniae DNA was detected in buffy-coat samples of 18 (20%) patients and 8 (9%) control subjects (adjusted odds ratio 2.9, 95% confidence interval 1-8.5). IgG antibodies to Chlamydia pneumoniae were detected in 85 (97%) patients and 71 (81%) control subjects (adjusted odds ratio 7.2, 95% confidence interval 1.7-31). The results show an association between abdominal aortic aneurysm and either the presence of Chlamydia pneumoniae DNA in buffy-coat samples or IgG antibodies to Chlamydia pneumoniae. These findings support the hypothesis that previous infection with Chlamydia pneumoniae might be a risk factor for abdominal aortic aneurysm.
Clinical Microbiology and Infection, 2007
Cat-scratch disease (CSD), caused by Bartonella henselae infection, can mimic malignancy and can ... more Cat-scratch disease (CSD), caused by Bartonella henselae infection, can mimic malignancy and can manifest atypically. Reliable serological testing is therefore of great clinical importance. The diagnostic performance of immunofluorescence assay (IFA) and ELISA was evaluated in a group of Dutch patients with proven CSD (clinical diagnosis confirmed by PCR). Sera of 51 CSD patients and 56 controls (patients with similar symptoms, but who were B. henselae PCR-negative and had an alternative confirmed diagnosis) were tested for anti-B. henselae IgM and IgG by IFA and ELISA. A commercially available IFA test for IgM had a sensitivity of 6%. In-house assays for IgM showed specificities of 93% (IFA) and 91% (ELISA), but with low sensitivities (53% and 65%, respectively). With a specificity of 82% (IFA) and 91% (ELISA), in-house IgG testing showed a significantly higher sensitivity in IFA (67%) than in ELISA (28%, p <0.01). Sensitivity was higher for genotype I (38-75%) than for genotype II (7-67%) infections, but this was only statistically significant for IgG ELISA (p <0.05). In conclusion, detection of IgM against B. henselae by in-house ELISA and IFA was highly specific for the diagnosis of CSD. The high seroprevalence in healthy individuals limits the clinical value of IgG detection for diagnosing CSD. Given the low sensitivity of the serological assays, negative serology does not rule out CSD and warrants further investigation, including PCR. Adding locally isolated (e.g., genotype II) B. henselae strains to future tests might improve the sensitivity.
European Journal of Clinical Microbiology & Infectious Diseases, 2012
Legionnaires&amp;#39; disease (LD) is an acute pneumonia caused by the inhalation or aspi... more Legionnaires&amp;#39; disease (LD) is an acute pneumonia caused by the inhalation or aspiration of aerosols contaminated with the Legionella bacteria. In the Netherlands, around 300 LD cases per year were reported between 2000 and 2008, but in 2009, the number dropped to 251, which was the lowest number in the previous 5 years of surveillance. We investigated if this decrease could be explained by the number of performed Legionella diagnostic tests in this year. We analyzed the number of tests performed between 2007 and 2009 in three large microbiological laboratories in different geographical regions in the Netherlands. Our data showed that there was no decrease in the number of patients for whom a diagnostic test for Legionella was performed in this period. These results are not in line with our hypothesis that the decrease in reported Legionella pneumonia patients in 2009 would be due to a decrease in patients for whom a diagnostic test was performed. We conclude that it is more likely that other factors such as the influence of weather patterns might explain the sudden drop in reported Legionella pneumonia patients in 2009 compared to the previous years, and it would be interesting to investigate this for the period described.
and enzyme-linked immunoassay. henselae-based indirect fluorescence assay serology: evaluation of... more and enzyme-linked immunoassay. henselae-based indirect fluorescence assay serology: evaluation of Bartonella Pitfalls and fallacies of cat scratch disease
Tumour Virus Research, 2021
Concurrent genital-anal human papillomavirus (HPV) infections may impose an increased anal cancer... more 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 analyzed viral load in concurrent genital-anal HPV infections, relative to genital-only and anal-only HPV infections and the impact of vaccination in young women. We included 1074 women, who provided both genital and anal swabs. HPV detection and genotyping was performed using the SPF10-DEIA-LiPA25. HPV copy numbers were measured with type-specific qPCRs and corrected for cellular content to obtain the viral load. Concurrent genital-anal HPV often had significantly higher genital viral load (0.09–371 c/cell) than genital-only HPV (3.17E-04-15.9 c/cell, p < 0.0001 to p < 0.05). Moreover, nearly all concurrent genital-anal HPV types had higher genital copy numbers per PCR reaction (157-416E04 c/rxn) than anal copy numbers (0.90–884E01 c/rxn, p < 0.0001 to p < 0.001). Vaccinated women had significantly less infections with HPV16/18 vaccine-types (2.8% vs 13.7%, p < 0.0001) and HPV31/35/45 cross-protective types (7.4% vs 21.1%, p < 0.0001) than unvaccinated women. In conclusion, particularly high genital viral load is found in concurrent genital-anal HPV infections, which are effectively reduced by vaccination.
Clinical Infectious Diseases, 2020
Background Human papillomavirus (HPV) vaccination programs achieve substantial population-level i... more Background Human papillomavirus (HPV) vaccination programs achieve substantial population-level impact, with effects extending beyond protection of vaccinated individuals. We assessed trends in HPV prevalence up to 8 years postvaccination among men and women in the Netherlands, where bivalent HPV vaccination, targeting HPV types 16/18, has been offered to (pre)adolescent girls since 2009 with moderate vaccination coverage. Methods We used data from the PASSYON study, a survey initiated in 2009 (prevaccination) and repeated biennially among 16- to 24-year-old visitors of sexual health centers. We studied genital HPV positivity from 2009 to 2017 among women, heterosexual men, and unvaccinated women using Poisson generalized estimating equation models, adjusted for individual- and population-level confounders. Trends were studied for 25 HPV types detected by the SPF10-LiPA25 platform. Results A total of 6354 women (64.7% self-reported unvaccinated) and 2414 heterosexual men were includ...
Journal of Clinical Microbiology, 1999
Repetitive sequence-based (Rep)-PCR genotyping as described here is based on the presence of homo... more Repetitive sequence-based (Rep)-PCR genotyping as described here is based on the presence of homologues of Mycoplasma pneumoniae repeat-like elements in Staphylococcus . In this study we comparatively evaluated the usefulness of rep-PCR typing with two sets of well-defined collections of Staphylococcus aureus strains. Rep-PCR analysis of the first collection of S. aureus strains ( n = 59) and one Staphylococcus intermedius strain showed 14 different rep-PCR patterns, with each pattern harboring 6 to 15 DNA fragments. The discriminatory power of rep-PCR typing compared well to those of arbitrarily primed PCR (average of 20 types) and pulsed-field gel electrophoresis (11 types). S. aureus strain collection I comprised four outbreak-related groups of isolates. The isolates in only one group were found to have identical rep-PCR profiles. However, in an analysis of isolates from three additional independent local outbreaks ( n for outbreaks 1 and 2 = 5, n for outbreak 3 = 12), identical ...
Journal of Clinical Microbiology, 1997
The diagnostic value of the detection of immunoglobulin G (IgG) and IgM by Bartonella henselae-ba... more The diagnostic value of the detection of immunoglobulin G (IgG) and IgM by Bartonella henselae-based indirect fluorescence assay (IFA) and enzyme-linked immunoassay (EIA) for the diagnosis of cat scratch disease (CSD) was evaluated. The IFA was performed either with B. henselae that was cocultivated for a few hours with Vero cells or with noncocultivated B. henselae as the antigen. Additionally, the performance of a Bartonella PCR hybridization assay based on the 16S rRNA gene was determined and compared with those of the serologic assays. The study group consisted of 45 patients suspected of suffering from CSD by fulfilling one or more of the classical criteria. The specificities of the immunoassays were set at > or = 95% by analysis of sera from 60 healthy blood donors. It is shown that the sensitivities of the IgG assays are very low (40.9% for the IFA with noncocultivated B. henselae as antigen) and that those of the IgM assays are higher (71.4% for the EIA) for patients who ...
The Journal of infectious diseases, Jan 4, 2018
Observational postmarketing studies are important to assess vaccine effectiveness (VE). We estima... more Observational postmarketing studies are important to assess vaccine effectiveness (VE). We estimated VE from the bivalent human papillomavirus (HPV) vaccine against HPV positivity of vaccine and nonvaccine types in a high-risk population. We included all vaccine-eligible women from the PASSYON study, a biennial cross-sectional survey in Dutch sexually transmitted infection clinics. Vaginal swabs were analyzed using a polymerase chain reaction-based assay (SPF10-LiPA25) able to detect the 12 high-risk HPV (hrHPV) types 16/18/31/33/35/39/45/51/52/56/58/59. We compared hrHPV positivity between self-reported vaccinated (≥1 dose) and unvaccinated women, and estimated VE by a logistic mixed model. We included 1087 women of which 53% were hrHPV positive and 60% reported to be vaccinated. The adjusted pooled VE against HPV-16/18 was 89.9% (81.7%-94.4%). Moreover, we calculated significant VE against nonvaccine types HPV-45 (91%), HPV-35 (57%), HPV-31 (50%), and HPV-52 (37%). Among women who...
Journal of Infection, 2017
Condylomata acuminata; Warts; Vaccination; Human papillomavirus vaccine, L1 type 16, 18; Preventi... more Condylomata acuminata; Warts; Vaccination; Human papillomavirus vaccine, L1 type 16, 18; Prevention & control Methods: We included all vaccine-eligible women from the PASSYON study, a biennial crosssectional study among 16-to 24-year-old sexually transmitted infection (STI) clinic attendants. Vaginal self-swabs were analyzed for type specific HPV and AGW were diagnosed at the STIclinic. Prevalence of HPV-6 and/or HPV-11 and AGW were compared between self-reported vaccinated and unvaccinated women by log-binomial regression analysis, adjusted for demographics and risk behavior. Results: Of the 1198 women included, 56% reported to be vaccinated at least once. Relative to unvaccinated women, the adjusted prevalence ratio (PR) for HPV-6/11 was 1.03 (95% confidence interval [CI] 0.74e1.43) for women vaccinated at least once. The crude PR for AGW was 0.67 (95% CI 0.22e2.07) for women vaccinated at least once. Adjustment did not change these results. Conclusions: We observed no cross-protective effect of the bivalent vaccine on genital HPV-6/ 11 positivity and a non-significant partially protective effect on AGW.
This study was aimed at contributing to finding the source of a epidemic of Legionnaire&a... more This study was aimed at contributing to finding the source of a epidemic of Legionnaire&amp;amp;amp;#39;s disease (LD) in visitors of the Westfriese Flora 1999 (West-Frisian Flower-show). The Westfriese Flora is a yearly flower exhibition combined with an agricultural and consumer products fair. The study targeted all persons without LD who had been working on the Westfriese Flora as volunteer, employee
Journal of Clinical Microbiology, 2002
European Journal of Clinical Microbiology & Infectious Diseases, 2012
Legionnaires&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; disease (LD) is an acute pneumonia ... more Legionnaires&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; disease (LD) is an acute pneumonia caused by the inhalation or aspiration of aerosols contaminated with the Legionella bacteria. In the Netherlands, around 300 LD cases per year were reported between 2000 and 2008, but in 2009, the number dropped to 251, which was the lowest number in the previous 5 years of surveillance. We investigated if this decrease could be explained by the number of performed Legionella diagnostic tests in this year. We analyzed the number of tests performed between 2007 and 2009 in three large microbiological laboratories in different geographical regions in the Netherlands. Our data showed that there was no decrease in the number of patients for whom a diagnostic test for Legionella was performed in this period. These results are not in line with our hypothesis that the decrease in reported Legionella pneumonia patients in 2009 would be due to a decrease in patients for whom a diagnostic test was performed. We conclude that it is more likely that other factors such as the influence of weather patterns might explain the sudden drop in reported Legionella pneumonia patients in 2009 compared to the previous years, and it would be interesting to investigate this for the period described.
Journal of Medical Microbiology, 2010
Bartonella henselae serology
This study reports the development and evaluation of an internally controlled real-time PCR targe... more This study reports the development and evaluation of an internally controlled real-time PCR targeting the ospA gene for detection of Borrelia burgdorferi sensu stricto, Borrelia garinii, Borrelia afzelii and Borrelia valaisiana. DNA was extracted using QIAamp DNA Blood Mini kit columns. DNA from 33 B. burgdorferi sensu lato strains reacted in the assay, whereas no reactivity was observed with DNA from four relapsing fever Borrelia spp., 11 unrelated spirochaetes, and 31 unrelated microorganisms. The quantitative sensitivity of the assay was 1-10 fg of Borrelia DNA and one to five cultured Borrelia spirochaetes. Cerebrospinal fluid (CSF) specimens from 70 patients sent for routine testing for neuroborreliosis, and three CSF specimens containing B. garinii were also tested. Positive PCR results were obtained with all three culture-confirmed neuroborreliosis specimens, five of ten neuroborreliosis specimens with specific antibodies in CSF and pleocytosis, none of nine specimens from possible cases of early neuroborreliosis (antibodies in serum, CSF pleocytosis, no antibodies in CSF), one of 15 specimens from patients with active or past Lyme disease with neurological signs (antibodies in serum, no pleocytosis or antibodies in CSF), and none of 36 specimens from patients without Lyme borreliosis (no antibodies in serum or CSF). Overall, the real-time PCR assay enabled sensitive and specific detection of all B. burgdorferi sensu lato species tested. The PCR had a sensitivity of 50% in patients with neuroborreliosis. The main diagnostic role of the assay could be to confirm neuroborreliosis in patients for whom the diagnosis is doubtful.
Journal of Medical Microbiology, 2008
Journal of Clinical Microbiology, 2002
European Journal of Clinical Microbiology and Infections Diseases, 2001
Recent studies have suggested that Chlamydia pneumoniae infection is a risk factor for abdominal ... more Recent studies have suggested that Chlamydia pneumoniae infection is a risk factor for abdominal aortic aneurysm. This study explores the presence of Chlamydia pneumoniae DNA in buffy-coat samples of control subjects and of patients with abdominal aortic aneurysm. The seroepidemiological association between abdominal aortic aneurysm and Chlamydia pneumoniae was also investigated. Buffy-coat samples and serum specimens were obtained from 88 patients and 88 control subjects. Detection of Chlamydia pneumoniae DNA in buffy-coat samples and measurement of IgG antibodies to Chlamydia pneumoniae in serum specimens were performed by polymerase chain reaction and microimmunofluorescence, respectively. Chlamydia pneumoniae DNA was detected in buffy-coat samples of 18 (20%) patients and 8 (9%) control subjects (adjusted odds ratio 2.9, 95% confidence interval 1-8.5). IgG antibodies to Chlamydia pneumoniae were detected in 85 (97%) patients and 71 (81%) control subjects (adjusted odds ratio 7.2, 95% confidence interval 1.7-31). The results show an association between abdominal aortic aneurysm and either the presence of Chlamydia pneumoniae DNA in buffy-coat samples or IgG antibodies to Chlamydia pneumoniae. These findings support the hypothesis that previous infection with Chlamydia pneumoniae might be a risk factor for abdominal aortic aneurysm.
Clinical Microbiology and Infection, 2007
Cat-scratch disease (CSD), caused by Bartonella henselae infection, can mimic malignancy and can ... more Cat-scratch disease (CSD), caused by Bartonella henselae infection, can mimic malignancy and can manifest atypically. Reliable serological testing is therefore of great clinical importance. The diagnostic performance of immunofluorescence assay (IFA) and ELISA was evaluated in a group of Dutch patients with proven CSD (clinical diagnosis confirmed by PCR). Sera of 51 CSD patients and 56 controls (patients with similar symptoms, but who were B. henselae PCR-negative and had an alternative confirmed diagnosis) were tested for anti-B. henselae IgM and IgG by IFA and ELISA. A commercially available IFA test for IgM had a sensitivity of 6%. In-house assays for IgM showed specificities of 93% (IFA) and 91% (ELISA), but with low sensitivities (53% and 65%, respectively). With a specificity of 82% (IFA) and 91% (ELISA), in-house IgG testing showed a significantly higher sensitivity in IFA (67%) than in ELISA (28%, p <0.01). Sensitivity was higher for genotype I (38-75%) than for genotype II (7-67%) infections, but this was only statistically significant for IgG ELISA (p <0.05). In conclusion, detection of IgM against B. henselae by in-house ELISA and IFA was highly specific for the diagnosis of CSD. The high seroprevalence in healthy individuals limits the clinical value of IgG detection for diagnosing CSD. Given the low sensitivity of the serological assays, negative serology does not rule out CSD and warrants further investigation, including PCR. Adding locally isolated (e.g., genotype II) B. henselae strains to future tests might improve the sensitivity.
European Journal of Clinical Microbiology & Infectious Diseases, 2012
Legionnaires&amp;#39; disease (LD) is an acute pneumonia caused by the inhalation or aspi... more Legionnaires&amp;#39; disease (LD) is an acute pneumonia caused by the inhalation or aspiration of aerosols contaminated with the Legionella bacteria. In the Netherlands, around 300 LD cases per year were reported between 2000 and 2008, but in 2009, the number dropped to 251, which was the lowest number in the previous 5 years of surveillance. We investigated if this decrease could be explained by the number of performed Legionella diagnostic tests in this year. We analyzed the number of tests performed between 2007 and 2009 in three large microbiological laboratories in different geographical regions in the Netherlands. Our data showed that there was no decrease in the number of patients for whom a diagnostic test for Legionella was performed in this period. These results are not in line with our hypothesis that the decrease in reported Legionella pneumonia patients in 2009 would be due to a decrease in patients for whom a diagnostic test was performed. We conclude that it is more likely that other factors such as the influence of weather patterns might explain the sudden drop in reported Legionella pneumonia patients in 2009 compared to the previous years, and it would be interesting to investigate this for the period described.