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1.  Evaluation of the presence and zoonotic transmission of Chlamydia suis in a pig slaughterhouse 
BMC Infectious Diseases  2014;14(1):560.
Background
A significant number of studies on pig farms and wild boars worldwide, demonstrate the endemic presence of Chlamydia suis in pigs. However, the zoonotic potential of this pathogen, phylogenetically closely related to Chlamydia trachomatis, is still uninvestigated. Therefore, this study aims to examine the zoonotic transmission in a Belgian pig abattoir.
Methods
Presence of Chlamydia suis in pigs, contact surfaces, air and employees was assessed using a Chlamydia suis specific real-time PCR and culture. Furthermore, Chlamydia suis isolates were tested for the presence of the tet(C) gene.
Results
Chlamydia suis bacteria could be demonstrated in samples from pigs, the air and contact surfaces. Moreover, eye swabs of two employees were positive for Chlamydia suis by both PCR and culture. The tet(C) gene was absent in both human Chlamydia suis isolates and no clinical signs were reported.
Conclusions
These findings suggest the need for further epidemiological and clinical research to elucidate the significance of human ocular Chlamydia suis infections.
doi:10.1186/s12879-014-0560-x
PMCID: PMC4216655  PMID: 25358497
Chlamydia suis; Swine; Zoonosis; Tetracycline; Public health
2.  Serovar D and E of serogroup B induce highest serological responses in urogenital Chlamydia trachomatis infections 
Background
Chlamydia trachomatis is the most prevalent bacterial sexually transmitted infection (STI) worldwide. A strong link between C. trachomatis serogroup/serovar and serological response has been suggested in a previous preliminary study. The aim of the current study was to confirm and strengthen those findings about serological IgG responses in relation to C. trachomatis serogroups and serovars.
Methods
The study population (n = 718) consisted of two patient groups with similar characteristics of Dutch STI clinic visitors. We performed genotyping of serovars and used titre based and quantitative commercially available ELISA kits (medac Diagnostika) to determine specific serum IgG levels. Optical density (OD) values generated by both tests were used to calculate the IgG titres (cut-off 1:50). Analyses were conducted stratified by gender.
Results
We observed very significant differences when comparing the median IgG titres of three serogroups, B, C and I: in women for B vs. C: p < 0.0001 (median titres B 200 vs. C <50); B vs. I: p < 0.0001 (200 vs. 50), and in men for B vs. C: p = 0.0006 (150 vs. <50); B vs. I: p = 0.0001 (150 vs. <50); C vs. I was not significant for both sexes. Serovars D and E of serogroup B had the highest median IgG titres compared to the other serovars in both men and women: 200 and 200 vs. ≤ 100 for women and 100 and 200 vs. ≤ 75 for men, respectively.
Conclusions
This study shows that B group serovars induce higher serological responses compared to the C and I group serovars in vivo in both men and women.
doi:10.1186/1471-2334-14-3
PMCID: PMC3893429  PMID: 24383586
Chlamydia trachomatis; Serological response; Serovar; Serogroup; IgG; Antibodies
3.  Addition of host genetic variants in a prediction rule for post meningitis hearing loss in childhood: a model updating study 
BMC Infectious Diseases  2013;13:340.
Background
Sensorineural hearing loss is the most common sequela in survivors of bacterial meningitis (BM). In the past we developed a validated prediction model to identify children at risk for post-meningitis hearing loss. It is known that host genetic variations, besides clinical factors, contribute to severity and outcome of BM. In this study it was determined whether host genetic risk factors improve the predictive abilities of an existing model regarding hearing loss after childhood BM.
Methods
Four hundred and seventy-one Dutch Caucasian childhood BM were genotyped for 11 single nucleotide polymorphisms (SNPs) in seven different genes involved in pathogen recognition. Genetic data were added to the original clinical prediction model and performance of new models was compared to the original model by likelihood ratio tests and the area under the curve (AUC) of the receiver operating characteristic curves.
Results
Addition of TLR9-1237 SNPs and the combination of TLR2 + 2477 and TLR4 + 896 SNPs improved the clinical prediction model, but not significantly (increase of AUC’s from 0.856 to 0.861 and from 0.856 to 0.875 (p = 0.570 and 0.335, respectively). Other SNPs analysed were not linked to hearing loss.
Conclusions
Although addition of genetic risk factors did not significantly improve the clinical prediction model for post-meningitis hearing loss, AUC’s of the pre-existing model remain high after addition of genetic factors. Future studies should evaluate whether more combinations of SNPs in larger cohorts has an additional value to the existing prediction model for post meningitis hearing loss.
doi:10.1186/1471-2334-13-340
PMCID: PMC3726293  PMID: 23879305
Genetics; SNP; Risk; Prediction; Bacterial meningitis; Hearing loss; Child
4.  Toll-like receptor 9 polymorphisms are associated with severity variables in a cohort of meningococcal meningitis survivors 
BMC Infectious Diseases  2012;12:112.
Background
Genetic variation in immune response genes is associated with susceptibility and severity of infectious diseases. Toll-like receptor (TLR) 9 polymorphisms are associated with susceptibility to develop meningococcal meningitis (MM). The aim of this study is to compare genotype distributions of two TLR9 polymorphisms between clinical severity variables in MM survivors.
Methods
We used DNA samples of a cohort of 390 children who survived MM. Next, we determined the genotype frequencies of TLR9 -1237 and TLR9 +2848 polymorphisms and compared these between thirteen clinical variables associated with prognostic factors predicting adverse outcome of bacterial meningitis in children.
Results
The TLR9 -1237 TC and CC genotypes were associated with a decreased incidence of a positive blood culture for Neisseria (N.) meningitidis (p = 0.014, odds ratio (OR) 0.5. 95% confidence interval (CI) 0.3 – 0.9). The TLR9 +2848 AA mutant was associated with a decreased incidence of a positive blood culture for N. meningitidis (p = 0.017, OR 0.6, 95% CI 0.3 – 0.9). Cerebrospinal fluid (CSF) leukocytes per μL were higher in patients carrying the TLR9 -1237 TC or CC genotypes compared to carriers of the TT wild type (WT) (p = 0.024, medians: 2117, interquartile range (IQR) 4987 versus 955, IQR 3938). CSF blood/glucose ratios were lower in TLR9 -1237 TC or CC carriers than in carriers of the TT WT (p = 0.017, medians: 0.20, IQR 0.4 versus 0.35, IQR 0.5). CSF leukocytes/μL were higher in patients carrying the TLR9 +2848 AA mutant compared to carriers of GG or GA (p = 0.0067, medians: 1907, IQR 5221 versus 891, IQR 3952).
Conclusions
We identified TLR9 genotypes associated with protection against meningococcemia and enhanced local inflammatory responses inside the central nervous system, important steps in MM pathogenesis and defense.
doi:10.1186/1471-2334-12-112
PMCID: PMC3443431  PMID: 22577991
5.  Evaluation of sexual history-based screening of anatomic sites for chlamydia trachomatis and neisseria gonorrhoeae infection in men having sex with men in routine practice 
BMC Infectious Diseases  2011;11:203.
Background
Sexually transmitted infection (STI) screening programmes are implemented in many countries to decrease burden of STI and to improve sexual health. Screening for Chlamydia trachomatis and Neisseria gonorrhoeae has a prominent role in these protocols. Most of the screening programmes concerning men having sex with men (MSM) are based on opportunistic urethral testing. In The Netherlands, a history-based approach is used. The aim of this study is to evaluate the protocol of screening anatomic sites for C. trachomatis and N. gonorrhoeae infection based on sexual history in MSM in routine practice in The Netherlands.
Methods
All MSM visiting the clinic for STI in The Hague are routinely asked about their sexual practice during consulting. As per protocol, tests for urogenital, oropharyngeal and anorectal infection are obtained based on reported site(s) of sexual contact. All consultations are entered into a database as part of the national STI monitoring system. Data of an 18 months period were retrieved from this database and analysed.
Results
A total of 1455 consultations in MSM were registered during the study period. The prevalence of C. trachomatis and N. gonorrhoeae per anatomic site was: urethral infection 4.0% respectively and 2.8%, oropharynx 1.5% and 4.2%, and anorectum 8.2% and 6.0%. The majority of chlamydia cases (72%) involved a single anatomic site, which was especially manifest for anorectal infections (79%), while 42% of gonorrhoea cases were single site. Twenty-six percent of MSM with anorectal chlamydia and 17% with anorectal gonorrhoea reported symptoms of proctitis; none of the oropharyngeal infections were symptomatic. Most cases of anorectal infection (83%) and oropharyngeal infection (100%) would have remained undiagnosed with a symptom-based protocol.
Conclusions
The current strategy of sexual-history based screening of multiple anatomic sites for chlamydia and gonorrhoea in MSM is a useful and valid guideline which is to be preferred over a symptom-based screening protocol.
doi:10.1186/1471-2334-11-203
PMCID: PMC3162902  PMID: 21791061
Chlamydia trachomatis; Neisseria gonorrhoeae; anorectal; oropharyngeal; screening
6.  Anal infections with concomitant Chlamydia trachomatis genotypes among men who have sex with men in Amsterdam, the Netherlands 
Background
Lymphogranuloma venereum (LGV) proctitis is caused by Chlamydia trachomatis (Ct) genotype L and is endemic among men who have sex with men (MSM) in western society. Genotype L infections need to be distinguished from non-LGV (genotypes A-K) Ct infections since they require prolonged antibiotic treatment. For this purpose, an in-house developed pmpH based LGV polymerase chain reaction (PCR) test is used at the Amsterdam STI outpatient clinic. We investigated retrospectively the anal Ct genotype distribution, and the frequency of concomitant genotype infections in MSM infected with LGV and non-LGV Ct infections. To detect concomitant Ct genotype infections, the pmpH LGV PCR and genoTyping Reverse Hybridization Assay (Ct-DT RHA) were used.
Methods
A total of 201 Ct positive rectal swabs from MSM were selected, which were previously diagnosed as either LGV (n = 99) or non-LGV Ct infection (n = 102) according to the algorithm of Ct detection by the commercially available Aptima Combo 2 assay followed by an in-house pmpH LGV PCR. The samples were retested with the commercially available Ct-DT RHA, which differentiates between 14 major genotypes and is able to detect concomitant Ct genotypes.
Results
Excellent genotyping agreement was observed between the Ct-DT RHA and the pmpH LGV PCR (Kappa = 0.900, 95%CI = 0.845-0.955, McNemar's p = 1.000). A concomitant non-LGV genotype was detected in 6/99 (6.1%) LGV samples. No additional LGV infections were observed with the Ct-DT RHA among the non-LGV Ct group. In the non-LGV group genotype G/Ga (34.3%) was seen most frequent, followed by genotype D/Da (22.5%) and genotype J (13.7%). All LGV infections were caused by genotype L2.
Conclusions
Concomitant non-LGV genotypes do not lead to missed LGV proctitis diagnosis. The pmpH LGV PCR displayed excellent agreement with the commercially available Ct-DT genotyping RHA test. The genotypes G/Ga, D/Da and J were the most frequent non-LGV Ct strains in MSM.
doi:10.1186/1471-2334-11-63
PMCID: PMC3068958  PMID: 21401939
7.  Do host genetic traits in the bacterial sensing system play a role in the development of Chlamydia trachomatis-associated tubal pathology in subfertile women? 
Background
In women, Chlamydia (C.) trachomatis upper genital tract infection can cause distal tubal damage and occlusion, increasing the risk of tubal factor subfertility and ectopic pregnancy. Variations, like single nucleotide polymorphisms (SNPs), in immunologically important host genes are assumed to play a role in the course and outcome of a C. trachomatis infection. We studied whether genetic traits (carrying multiple SNPs in different genes) in the bacterial sensing system are associated with an aberrant immune response and subsequently with tubal pathology following a C. trachomatis infection. The genes studied all encode for pattern recognition receptors (PRRs) involved in sensing bacterial components.
Methods
Of 227 subfertile women, serum was available for C. trachomatis IgG antibody testing and genotyping (common versus rare allele) of the PRR genes TLR9, TLR4, CD14 and CARD15/NOD2. In all women, a laparoscopy was performed to assess the grade of tubal pathology. Tubal pathology was defined as extensive peri-adnexal adhesions and/or distal occlusion of at least one tube.
Results
Following a C. trachomatis infection (i.e. C. trachomatis IgG positive), subfertile women carrying two or more SNPs in C. trachomatis PRR genes were at increased risk of tubal pathology compared to women carrying less than two SNPs (73% vs 33% risk). The differences were not statistically significant (P = 0.15), but a trend was observed.
Conclusion
Carrying multiple SNPs in C. trachomatis PRR genes tends to result in an aberrant immune response and a higher risk of tubal pathology following a C. trachomatis infection. Larger studies are needed to confirm our preliminary findings.
doi:10.1186/1471-2334-6-122
PMCID: PMC1555588  PMID: 16859562
8.  The CD14 functional gene polymorphism -260 C>T is not involved in either the susceptibility to Chlamydia trachomatis infection or the development of tubal pathology 
Background
The functional polymorphism -260 C>T in the LPS sensing TLR4 co-receptor CD14 gene enhances the transcriptional activity and results in a higher CD14 receptor density. Individuals carrying the T/T genotype also have significantly higher serum levels of soluble CD14. The T allele of this polymorphism has recently been linked to Chlamydia pneumoniae infection. We investigated the role of the CD14 -260 C>T polymorphism in the susceptibility to and severity (defined as subfertility and/or tubal pathology) of C. trachomatis infection in Dutch Caucasian women.
Methods
The different CD14 -260 C>T genotypes were assessed by PCR-based RFLP analysis in three cohorts: 1) A cohort (n = 576) of women attending a STD clinic, 2) a cohort (n = 253) of women with subfertility, and 3) an ethnically matched control cohort (n = 170). The following variables were used in the analysis: In cohort 1 the CT-DNA status, CT IgG serology status, self-reported symptoms and in cohort 2, the CT IgG serology status and the tubal status at laparoscopy.
Results
In the control cohort the CC, CT and TT genotype distribution was: 28.2%, 48.2%, and 23.5% respectively. No differences were found in the overall prevalence of CD14 -260 genotypes (28.1%, 50.7%, and 21.2%) in cohort 1 when compared to the control cohort. Also no differences were observed in women with or without CT-DNA, with or without serological CT responses, with or without symptoms, or in combinations of these three variables. In subfertile women with tubal pathology (cohort 2, n = 50) the genotype distribution was 28.0%, 48.0%, and 24.0% and in subfertile women without tubal pathology (n = 203), 27.6%, 49.3% and 23.2%. The genotype distribution was unchanged when CT IgG status was introduced in the analyses.
Conclusion
The CD14 -260 C>T genotype distributions were identical in all three cohorts, showing that this polymorphism is not involved in the susceptibility to or severity of sequelae of C. trachomatis infection.
doi:10.1186/1471-2334-5-114
PMCID: PMC1351185  PMID: 16368002
9.  Acquired homotypic and heterotypic immunity against oculogenital Chlamydia trachomatis serovars following female genital tract infection in mice 
Background
Chlamydia trachomatis is the most common sexually transmitted bacterial pathogen causing female genital tract infection throughout the world. Reinfection with the same serovar, as well as multiple infections with different serovars, occurs in humans. Using a murine model of female C. trachomatis genital tract infection, we determined if homotypic and/or heterotypic protection against reinfection was induced following infection with human oculogenital strains of C. trachomatis belonging to two serovars (D and H) that have been shown to vary significantly in the course of infection in the murine model.
Methods
Groups of outbred CF-1 mice were reinfected intravaginally with a strain of either serovar D or H, two months after initial infection with these strains. Cellular immune and serologic status, both quantitative and qualitative, was assessed following initial infection, and the course of infection was monitored by culturing vaginal samples collected every 2–7 days following reinfection.
Results
Serovar D was both more virulent (longer duration of infection) and immunogenic (higher level of circulating and vaginal IgG and higher incidence of IgA in vaginal secretions) in the mouse genital tract. Although both serovars induced cross-reacting antibodies during the course of primary infection, prior infection with serovar H resulted in only a slight reduction in the median duration of infection against homotypic reinfection (p ~ 0.10), while prior infection with serovar D resulted in significant reduction in the median duration of infection against both homotypic (p < 0.01) and heterotypic reinfection (p < 0.01) when compared to primary infection in age and conditions matched controls.
Conclusion
Serovar D infection resulted in significant homotypic and heterotypic protection against reinfection, while primary infection with serovar H resulted in only slight homotypic protection. In addition to being the first demonstration of acquired heterotypic immunity between human oculogenital serovars, the differences in the level and extent of this immunity could in part explain the stable difference in serovar prevalence among human isolates.
doi:10.1186/1471-2334-5-105
PMCID: PMC1318460  PMID: 16293190

Results 1-9 (9)