1. Interaction between bacteria and host tissue is important, both for primary adhesion and tissue-specific colonisation, as well as for pathogen invasion for different host tissues. 2. Ornithobacterium rhinotracheale is a bacterium associated with respiratory tract infections in poultry. The mechanisms by which O. rhinotracheale causes infection are not known. To date, at least 18 serovars of this bacterium, with or without the ability to agglutinate erythrocytes of chicken and other species, have been identified. 3. The purpose of this work was to evaluate the ability of five references strains, belonging to serovars A, B, C, D and E, to adhere to a culture of primary chicken tracheal cells. 4. Serovars A and B adhered to less than 20% of tracheal cells with no specific adherence pattern. Serovars C, D and E gave adherence values greater than 70%. Serovars C and E showed a diffuse adherence pattern, while serovar D had an aggregated adherence pattern. 5. The adherence ability and pattern could be associated with different pathogenicity mechanisms in the various serovars but more studies are needed to understand the reasons for these differences.

Chlamydia trachomatis is considered as a public health problem due to its high prevalence and increased rates of gynecological disorders. The major outer membrane protein (MOMP) of this bacterium is the most abundant protein in its membrane and has been evaluated not only as a vaccine development candidate but also is used in many diagnostic tests. The MOMP weighs 69 kDa and contains four variable segments (VS 1-4) separated by constant regions. Several research groups have developed recombinant single-variable segments of MOMP expressed in Escherichia coli cytoplasm. But, all variable segments have been used minimally for the diagnosis of a chlamydial infection. In this experiment, the authors obtained the recombinant MOMP of C. trachomatis (rMOMP) in E. coli rMOMP and extracted, purified, and partially characterized it. This was later used to identify anti-Chlamydia trachomatis antibodies in sera of infertile patients by immunodetection assays, enzyme-linked immunosorbent assay (ELISA), and indirect immunofluorescence tests. The ELISA test showed high sensitivity and low specificity of 100 and 58.3%, respectively. The above results obtained were linked to the cross-reactivity of antibodies against C. pneumoniae or C. psittaci. Hence, an evaluation was performed to obtain an optimized test for the diagnosis of C. trachomatis infection.

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Unfavorable pregnancy outcomes caused by Chlamydia trachomatis (C. trachomatis), such as premature rupture of membranes, preterm birth, and low birth weight, are well known. Mother-to-child transmission can occur at the time of birth and may result in conjunctivitis and pneumonia in the newborn. We therefore evaluated to question whether just one maternal screening for Chlamydia is enough to prevent adverse pregnancy and negative neonatal outcomes. Among the 4,087 first-time gynecological-obstetric consultations granted at the National Institute of Perinatology in 2018, we selected the study population according to a case-cohort design. Antenatal Chlamydia screening and treatment interventions were performed on 628 pregnant women using COBAS® TaqMan CT. Chlamydia DNA was also detected in samples from 157 infants of these mothers. We find that C. trachomatis positivity was detected in 10.5%. The vertical transmission rates were 1.5% for thecohort of mothers with a Chlamydia-positive test and 29.7% for those with a negative test. By evaluating symptomatic neonatal infection, the hazard rate of perinatal pneumonia was 3.6 times higher in Chlamydia-positive babies than in Chlamydia-negative babies. Despite the low rate of mother-to-child transmission in women positive for Chlamydia trachomatisdetected with a nucleic acid amplification test and who received timely treatment, possible maternal reinfectionthat is not detected during pregnancy significantly increases the risk of neonatal infection with consequent perinatal pneumonia.