Acute Chlamydia trachomatis respiratory infection in infants

Chlamydiaceae: Diseases in Primary Hosts and Zoonosis

Bacteria of the Chlamydiaceae family are a type of Gram-negative microorganism typified by their obligate intracellular lifestyle. The majority of the members in the Chlamydiaceae family are known pathogenic organisms that primarily infect the host mucosal surfaces in both humans and animals. For instance, Chlamydia trachomatis is a well-known etiological agent for ocular and genital sexually transmitted diseases, while C. pneumoniae has been implicated in community-acquired pneumonia in humans. Other chlamydial species such as C. abortus, C. caviae, C. felis, C. muridarum, C. pecorum, and C. psittaci are important pathogens that are associated with high morbidities in animals. Importantly, some of these animal pathogens have been recognized as zoonotic agents that pose a significant infectious threat to human health through cross-over transmission. The current review provides a succinct recapitulation of the characteristics as well as transmission for the previously established members of the Chlamydiaceae family and a number of other recently described chlamydial organisms.

Influence of different delivery modes on the clinical characteristics of Chlamydia trachomatis pneumonia

We analyzed the effects of delivery methods on Chlamydia trachomatis pneumonia in infants. Three hundred forty-four children hospitalized with Chlamydia trachomatis pneumonia were enrolled. They were divided into the vaginal delivery group and the cesarean delivery group. We compared and analyzed their age of onset, peripheral blood white blood cell count, liver enzymes, chlamydia trachomatis titers, and chest radiograph scores. Seventy-eight (22.7%) were delivered by a cesarean, and 266 (77.3%) were delivered vaginally. There were no statistically significant differences between groups when compared by sex and age (P > 0.05). Copy numbers and white blood cell counts in the peripheral blood of children with Chlamydia trachomatis in respiratory secretions of the vaginal delivery group were significantly higher than those of the cesarean delivery group (P < 0.05). The alanine aminotransferase and aspartate aminotransferase levels between groups were not statistically significant. Comparisons of admission chest radiography scores, discharge radiography scores, and score differences showed no statistical differences (P > 0.05).

CONCLUSION

Infants delivered by cesarean comprise approximately one-fifth of those affected. The Chlamydia trachomatis titers and peripheral blood leukocyte counts of the vaginal delivery group were higher than those of the cesarean delivery group. Age of onset, liver enzymes, pulmonary inflammation, and pneumonia absorption were not different between groups. What is Known: • Chlamydia trachomatis is an important pathogen that causes lower respiratory tract infections in infants. • C. trachomatis is primarily transmitted to infants through the infected mother, resulting in Chlamydia trachomatis pneumonia subsequently. What is New: • Vaginal delivery and cesarean delivery can result in Chlamydia trachomatis pneumonia transmission; however, cesarean delivery accounts for ~ 20% of cases. • C. trachomatis volume in the respiratory tract and the number of peripheral blood leukocytes in infants delivered vaginally were higher than those in infants delivered by cesarean.

IgA modulates respiratory dysfunction as a sequela to pulmonary chlamydial infection as neonates

Neonatal Chlamydia lung infections are associated with serious sequelae such as asthma and airway hyper-reactivity in children and adults. Our previous studies demonstrated the importance of Th-1 type cytokines, IL-12 and IFN-γ in protection against neonatal pulmonary chlamydial challenge; however, the role of the humoral arm of defense has not been elucidated. We hypothesized that B-cells and IgA, the major mucosal antibody, play a protective role in newborns against development of later life respiratory sequelae to Chlamydia infection. Our studies using neonatal mice revealed that all WT and IgA-deficient (IgA(-/-)) animals survived a sublethal pulmonary Chlamydia muridarum challenge at one day after birth with similar reduction in bacterial burdens over time. In contrast, all B-cell-deficient (μMT) mice succumbed to infection at the same challenge dose correlating to failure to control bacterial burdens in the lungs. Although IgA may not be important for bacterial clearance, we observed IgA(-/-) mice displayed greater respiratory dysfunction 5 weeks post challenge. Specifically, comparative respiratory functional analyses revealed a significant shift upward in P-V loops, and higher dynamic resistance in IgA(-/-) animals. This study provides insight(s) into the protective role of IgA in neonates against pulmonary chlamydial infection induced respiratory pathological sequelae observed later in life.

Wheezing exacerbations in early childhood: evaluation, treatment, and recent advances relevant to the genesis of asthma

Children who begin wheezing during early childhood are frequently seen by health care providers in primary care, in hospitals, and in emergency departments, and by allergists and pulmonologists. When a young child, such as the 2 year-old patient presented here, is evaluated for wheezing, a frequent challenge for clinicians is to determine whether the symptoms represent transient, viral-induced wheezing or whether sufficient risk factors are present to suspect that the child may experience recurrent wheezing and develop asthma. Most factors that influence prognosis are not mutually exclusive, are interrelated (ie, cofactors), and often represent gene-environment interactions. Many of these risk factors have been, and continue to be, investigated in prospective studies to decipher their relative importance with the goal of developing new therapies and interventions in the future. The etiologies of wheezing in young children, diagnostic methods, treatment, prognostic factors, and potential targets for prevention of the development of asthma are discussed.