Chlamydial Infections in Children and Adolescents

Objectives

After completing this article, readers should be able to:

1. Describe the varied clinical manifestations of Chlamydia trachomatis infection in neonates, children, and adolescents.

2. Know the clinical manifestations of Chlamydophila pneumoniae infection.

3. List the various diagnostic criteria and methods for C trachomatis and C pneumoniae infections.

4. Discuss the treatments for C trachomatis and C pneumoniae infections.

Introduction

Chlamydiae are obligate intracellular organisms that cause a wide spectrum of human and animal disease, including conjunctivitis, pneumonia, and genital tract infections. C trachomatis and C pneumoniae are significant human pathogens; C psittaci is a less common cause of human disease.

The earliest descriptions of what is believed to have been trachoma are found in ancient Chinese and Egyptian manuscripts. In 1907, Halberstaedter and von Prowazek found what they assumed (correctly) to be the causal agent in trachoma when they noted intracytoplasmic vacuoles with numerous particles in Giemsa-stained epithelial cells. Subsequently, similar inclusions were described in specimens taken from the eyes of babies who had ophthalmia neonatorum, from their mothers’ uteruses, and from men who had urethritis. From 1929 to 1930, outbreaks of an “atypical pneumonia” acquired from psittacine birds stimulated more research, which led to Bedson's description of the characteristic developmental life cycle of all Chlamydiales. His accurate description of “an obligate intracellular parasite with bacterial affinities” was not fully appreciated for several decades because these new agents initially were believed to be viruses.

Classification

Under the 2000 taxonomy, the order Chlamydiales was divided into four families: Chlamydiaceae, Parachlamydiaceae, Waddliaceae, and Simkaniaceae. The family Chlamydiaceae was divided further into two genera, Chlamydophila and Chlamydia, based on ribosomal sequence analysis that showed less than 95% homology between Chlamydia and Chlamydophila. Chlamydophila includes the species C pneumonia, C psittaci, and nonhuman pathogens; the family Chlamydia includes C trachomatis and nonhuman pathogens. (1 …