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Seroprevalence of different Chlamydia-like organisms in an asymptomatic population

2009; Elsevier BV; Volume: 15; Linguagem: Inglês

10.1111/j.1469-0691.2008.02134.x

1469-0691

David Baud, C. Kebbi, Jean-Pierre Kulling, Gilbert Greub,

Pediatric health and respiratory diseases

Accumulating evidence suggests that new obligate intracellular Chlamydia-like organisms may play a role as human pathogens [1Marrie TJ Raoult D La SB Birtles RJ de CE Legionella-like and other amoebal pathogens as agents of community-acquired pneumonia.Emerg Infect Dis. 2001; 7: 1026-1029Crossref PubMed Scopus (110) Google Scholar, 2Baud D Thomas V Arafa A Regan L Greub G Waddlia chondrophila, a potential agent of human fetal death.Emerg Infect Dis. 2007; 13: 1239-1243Crossref PubMed Scopus (107) Google Scholar, 3Casson N Michel R Muller KD Aubert JD Greub G Protochlamydia naegleriophila as etiologic agent of pneumonia.Emerg Infect Dis. 2008; 14: 168-172Crossref PubMed Scopus (55) Google Scholar]. Waddlia chondrophila, an abortigenic agent in bovines, might play a role in human miscarriage [2Baud D Thomas V Arafa A Regan L Greub G Waddlia chondrophila, a potential agent of human fetal death.Emerg Infect Dis. 2007; 13: 1239-1243Crossref PubMed Scopus (107) Google Scholar], while Parachlamydia acanthamoebae and Protochlamydia naegleriophila represent new aetiologic agents of pneumonia [1Marrie TJ Raoult D La SB Birtles RJ de CE Legionella-like and other amoebal pathogens as agents of community-acquired pneumonia.Emerg Infect Dis. 2001; 7: 1026-1029Crossref PubMed Scopus (110) Google Scholar, 3Casson N Michel R Muller KD Aubert JD Greub G Protochlamydia naegleriophila as etiologic agent of pneumonia.Emerg Infect Dis. 2008; 14: 168-172Crossref PubMed Scopus (55) Google Scholar]. However, the modes of transmission of these Chlamydia-related organisms and the populations at risk for infection with these strict intracellular bacteria are incompletely defined. Here, we tested sera taken from asymptomatic men in Switzerland for antibodies directed against these Chlamydia-like organisms to determine seroprevalence and to identify risks factors for seropositivity, i.e. exposure to these bacteria. Sera were also tested for a fourth Chlamydia-related organism, Criblamydia sequanensis [4Thomas V Casson N Greub G Criblamydia sequanensis, a new intracellular Chlamydiales isolated from Seine river water using amoebal co-culture.Environ Microbiol. 2006; 8: 2125-2135Crossref PubMed Scopus (96) Google Scholar], which was isolated from the water of the Seine river and whose pathogenic role has not yet been studied. Young Swiss men were enrolled in this cross-sectional study during their medical examination for compulsory military service [5Baud D Jaton K Bertelli C Kulling JP Greub G Low prevalence of Chlamydia trachomatis infection in asymptomatic young Swiss men.BMC Infect Dis. 2008; 8: 45Crossref PubMed Scopus (32) Google Scholar]. Demographic data, animal exposure and sexual risks factors were recorded using a questionnaire [5Baud D Jaton K Bertelli C Kulling JP Greub G Low prevalence of Chlamydia trachomatis infection in asymptomatic young Swiss men.BMC Infect Dis. 2008; 8: 45Crossref PubMed Scopus (32) Google Scholar]. Sera were first screened by immunofluorescence for antibody reactivity against Waddlia chondrophila, C. sequanensis, P. acanthamoebae and P. naegleriophila using as secondary antibody FluolineH (BioMerieux, Marcy l'Etoile, France) as reported [2Baud D Thomas V Arafa A Regan L Greub G Waddlia chondrophila, a potential agent of human fetal death.Emerg Infect Dis. 2007; 13: 1239-1243Crossref PubMed Scopus (107) Google Scholar]. Sera that exhibited a total Ig titre ≥1:64 were then tested for IgG and IgM reactivity using corresponding anti-human Ig fluorescein (FluolineG or FluolineM, BioMerieux). Each immunofluorescence was read blindly by two independent observers and congruent results were considered positive (98.1% and 97.5% concordance for Waddlia and Criblamydia, respectively). IgG and IgM positivity cut-offs were ≥1:64 and ≥1:32, respectively [2Baud D Thomas V Arafa A Regan L Greub G Waddlia chondrophila, a potential agent of human fetal death.Emerg Infect Dis. 2007; 13: 1239-1243Crossref PubMed Scopus (107) Google Scholar]. Positive immunofluorescences were confirmed by Western-blot, as described earlier [2Baud D Thomas V Arafa A Regan L Greub G Waddlia chondrophila, a potential agent of human fetal death.Emerg Infect Dis. 2007; 13: 1239-1243Crossref PubMed Scopus (107) Google Scholar]. Prevalence, confidence interval (95%CI) and odds ratio (OR) were calculated using STATA (College Station, TX, USA). Among 517 young Swiss men enrolled [5Baud D Jaton K Bertelli C Kulling JP Greub G Low prevalence of Chlamydia trachomatis infection in asymptomatic young Swiss men.BMC Infect Dis. 2008; 8: 45Crossref PubMed Scopus (32) Google Scholar], 482 gave their consent for blood sampling. Demographic characteristics and potential risk factors for seropositivity for Chlamydia-like organisms are shown in Table 1.TABLE 1Demogrphic characteristics, potential risk factors of chlamydial infection and underlying diseases according to Waddlia and Criblamydia serostatus.CharacteristicsTotalWaddlia positiveCriblamydia positiven(%)n(%)p-value*Odds ratio95% Cln(%)p-value*Odds ratio95% ClAge (year ± SD)20.6 ± 1.420.9 ± 1.720.8 ± 1.6≤2026454.820500.619ref2246.80.281ref>2021845.220501.230.64–2.352553.21.420.78–2.61Nationality at birth Switzerland40784.43587.50.941ref4289.40.408ref Europe398.137.50.890.26–3.0248.50.990.34–2.93 Other367.5250.630.14–2.7112.10.250.03–1.86Place of residence >10 000 inhabitants12873.414350.261ref8170.163ref <10 000 inhabitants35426.626651.550.78–3.0739830.540.24–1.19Main occupation Studies21845.220500.949ref2451.10.249ref Work25152.11947.51.10.57–2.122042.60.960.51–1.78 Declined to respond132.712.50.960.12–7.7936.42.840.73–11.02Monthly income 2000 Frs.10723.612301.50.71–3.151429.81.620.81–3.27 Declined to respond285.84101.980.63–6.21612.82.941.09–7.96Contact with animal25051.922550.7421.150.60–2.202655.30.6481.170.64–2.14 Farm animals132.712.510.920.12–7.2512.110.770.10–6.03 Dog10822.410250.6931.170.55–2.481327.70.3611.370.69–2.70 Cat16634.4143511.030.52–2.031940.40.4191.330.72–2.46Smoke/drugs Cigarettes22546.712300.460.23–0.932042.60.6450.830.45–1.53 Cannabis12525.6102510.950.45–2.001021.30.4890.750.36–1.56 Drugs193.9210.50.6661.320.29–5.91210.50.7071.090.24–4.88 Alcohol > 2×/week32667.624600.2930.70.36–1.352859.60.2510.680.37–1.26Any reported disease489.9512.50.5791.330.49–3.56919.20.0382.41.08–5.34 Asthma326.64100.3261.640.55–4.94714.90.0272.871.17–7.05 Any regular treatment5210.8917.30.0282.691.20–6.031019.20.0242.531.17–5.45Food Vegetarian61.212.50.4072.240.26–19.712.10.4621.870.21–16.35 Milk allergy112.300000.611-- Maternal feeding at birth44091.336900.7680.850.29–2.514493.60.7861.440.43–4.87Drink Water from city37778.23177.50.844ref3472.30.351ref Water in bottle10521.8922.51.050.48–2.271327.71.430.72–2.81Sport practice ≥ 1×/week34070.53177.50.3681.480.69–3.203676.60.4021.410.70–2.86Number of life sexual partners 06513.5717.50.373ref714.90.643ref 110922.6717.50.570.19–1.708170.660.23–1.90 ≥229761.624600.730.30–1.773268.110.42–2.38 Declined to respond112.3251.840.33–10.300--Sexual orientation Heterosexual36375.32972.50.282ref3676.60.943ref Homo/bisexual91.9253.290.65–16.612.11.140.14–9.34 Declined to respond11022.8922.51.020.47–2.241021.30.910.44–1.90Condom use Always15632.412300.189ref1940.40.422ref Sometimes22446.516400.930.42–2.012246.80.780.41–1.51 Never7014.56151.130.40–3.13510.60.550.20–1.55 Declined to respond326.66152.770.95–8.0412.10.240.03–1.80 Open table in a new tab Among 66 volunteers (13.7%, 95% CI 10.6–16.8) screened positive for Waddlia, 40 (8.3%, 95% CI 5.9–11.3) had IgG antibodies against this agent. Only three men (0.6%, 95% CI 0–1.3) exhibited IgM antibodies against Waddlia. No specific risks factors for Waddlia infection were identified. A total of 101 subjects (21%, 95% CI 17.7–25.5) were screened positive for Criblamydia. The prevalences of IgG and IgM antibody reactivity against Criblamydia were 8.3% (40/482, 95% CI 5.9–11.3) and 1.7% (8/482, 95% CI 0.5–2.8), respectively. Presence of dogs at home was associated with Criblamydia total Ig seropositivity, suggesting that this Chlamydia-like organism may be zoonotically transmitted. However, this association was not observed when considering patients with IgG or IgM positivity. Conversely, Criblamydia IgG seropositivity was associated with asthma (OR 2.9, 95% CI 1.2–7.1). This association between Criblamydia and asthma was stronger (OR 4.1, 95% CI 1.1–15.6) when an IgG cutoff of >1/256 was chosen. No volunteers exhibited significant IgG or IgM reactivity against Protochlamydia or Parachlamydia, although three men (0.6%, 95% CI 0.1–1.8) were positive for Parachlamydia during the screening phase that detected total antibody reactivity against Parachlamydia. Positivity was confirmed by Western-blots (data not shown). The three patients positive for Parachlamydia were negative for all other Chlamydia-like organisms tested. Interestingly, they lived in the same rural area (within a less than 20 km radius) and two of them were occupationally exposed to farm animals (2/12 vs. 1/467, p 0.002). Interestingly, 53.2% of IgG positive Criblamydia serologies were positive for Waddlia. Conversely, 62.5% of IgG positive Waddlia serologies were also positive for Criblamydia. None of the positive serologies observed here were associated with Chlamydia trachomatis infection [5Baud D Jaton K Bertelli C Kulling JP Greub G Low prevalence of Chlamydia trachomatis infection in asymptomatic young Swiss men.BMC Infect Dis. 2008; 8: 45Crossref PubMed Scopus (32) Google Scholar]. To identify cross-reacting immunogenic proteins, we performed Western blot analyses on sera positive only for Criblamydia and on sera positive for both Waddlia and Criblamydia, using C. sequanensis as antigen. Immunogenic proteins of 77, 69, 62, 57, 54 and 44 KDa were identified in both groups (Fig. 1). Rate of positivity was higher in patients with a concomitant positive Waddlia serology for proteins exhibiting 62, 57 and 44 kDa, suggesting that these proteins cross-reacted. This work demonstrates that exposure of humans to W. chondrophila and C. sequanensis is quite common, while exposure to P. acanthamoebae and P. naegleriophila may be limited. The Waddlia IgG seroprevalence of 8.3% we observed here was similar to that of 7.1% observed in 169 healthy pregnant women in the UK [2Baud D Thomas V Arafa A Regan L Greub G Waddlia chondrophila, a potential agent of human fetal death.Emerg Infect Dis. 2007; 13: 1239-1243Crossref PubMed Scopus (107) Google Scholar].