Chlamydia pneumoniae : studies on an emerging pathogen

The Chlamydiae are characterized as bacteria because of the composition of their cell wall and their growth by binary division. However, they are obligate intracellular bacterial parasites of eukaryotic cells that have a unique replication cycle similar to Rickettsia. Chlamydial infection of host cells is initiated by the elementary body (? = 300-400 nm) , a stable structure specifically adapted to survive the extracellular phase during transit between cells. According to the knowledge, the infectious elementary body enters the cell via endocytosis (90,118). Intracellular parasites have evolved several ways to avoid being killed by lysosomal enzymes (139). However, the mechanism by which subsequent fagosome/lysosome fusion is avoided, is not completely understood. After endocytosis of the elementary body, it will reorganize into a non-infectious, metabolic active reticulate body (? = 800 - 1000 nm), which is responsible for intracellular replication through binary fission. At both stages of development the chlamydial cell is surrounded by an envelope similar to that of gram-negative bacteria. The envelope consists of two trilalninar lnenlbranes, an outer lnelnbrane and an inner, cytoplasmic membrane (24). The fissions occur in the original phagosome that enlarges during this process until it resembles a vacuole. This vacuole is referred to as an inclusion body or in short, an inclusion. During replication, the reticulate body obtains adenosine triphosphate, amino acids and sugars fi'om the host cell (7). Each reticulate body will reorganize into one or more elementary bodies (204). After 48-72 hrs, release of infective elementary bodies will take place due to host cell lysis (Figure 1). The order Chlamydiales has one family, Chlamydiaceae, and one genus, Chlamydia. There are now four recognized species, Chlamydia trachomatis, Chlamydia psittaci, Chlamydia pneumoniae and Chlamydia pecol'1lm. Of these, the most recently described C.peCOl'llm infects sheep and cattle, and has so far not been associated with human disease (58,59). At this moment, 19 different C.tl'achomatis serovars or serotypes are known, i.e. distinguished from each other by polyclonal antibodies that were formed in mice after they have been infected with a single type Chlamydia (201)

Survival of Chlamydia pneumoniae following contact with various surfaces

Objective: In this study, the survival and recovery of Chlamydia pneumoniae (Cp) strains TW‐183, AR‐39, AR‐388 and CWL‐029 were measured after inoculation on glass, stainless steel, FormicaR laminate, paper, fabric and human skin. Methods: Inoculum in throat washes from healthy volunteers was applied to each surface. Samples were taken immediately after inoculum application and at specified intervals thereafter to determine infectivity. Results: Infectious Cp was recovered from glass for up to 4 h, from paper and fabric for up to 3 h, from FormicaR laminate for up to 2 h, from stainless steel for up to 60 min and from human skin for up to 30 min. Drying of the inoculated area had no significant effect on the recovery of infectious Cp. Further experiments demonstrated that infectious Cp could be transferred to hands by touching these contaminated surfaces and could be recovered from these hands for up to 3 min. Addition of albumin, surfactant or phosphatidylcholine had no significant effect on the survival of Cp. Conclusions: These results suggest that contact with contaminated surfaces may be a potential mode of transmission of Cp. 1995 European Society of Clinical Microbiology and Infectious Disease

Risk factors associated with Campylobacter jejuni infections in Curacao, Netherlands Antilles

A steady increase in the incidence of Guillain-Barre syndrome (GBS) with a seasonal preponderance, almost exclusively related to Campylobacter jejuni, and a rise in the incidence of laboratory-confirmed Campylobacter enteritis have been reported from Curacao, Netherlands Antilles. We therefore investigated possible risk factors associated with diarrhea due to epidemic C. jejuni. Typing by pulsed-field gel electrophoresis identified four epidemic clones which accounted for almost 60% of the infections. One hundred six cases were included in a case-control study. Infections with epidemic clones were more frequently observed in specific districts in Willemstad, the capital of Curacao. One of these clones caused infections during the rainy season only and was associated with the presence of a deep well around the house. Two out of three GBS-related C. jejuni isolates belonged to an epidemic clone. The observations presented point toward water as a possible source of Campylobacter infections

Cost-effectiveness analysis of Chlamydia trachomatis screening in Dutch pregnant women

Chlamydia trachomatis infections during pregnancy may have serious consequences for women and their offspring. Chlamydial infections are largely asymptomatic. Hence, prevention is based on screening. The objective of this study was to estimate the cost-effectiveness of C. trachomatis screening during pregnancy. We used a health-economic decision analysis model, which included potential health outcomes of C. trachomatis infection for women, partners and infants, and premature delivery. We estimated the cost-effectiveness from a societal perspective using recent prevalence data from a population-based prospective cohort study among pregnant women in the Netherlands. We calculated the averted costs by linking health outcomes with health care costs and productivity losses. Cost-effectiveness was expressed as net costs per major outcome prevented and was estimated in base-case analysis, sensitivity, and scenario analysis. In the base-case analysis, the costs to detect 1000 pregnant women with C. trachomatis were estimated at €527,900. Prevention of adverse health outcomes averted €626,800 in medical costs, resulting in net cost savings. Sensitivity analysis showed that net cost savings remained with test costs up to €22 (test price €19) for a broad range of variation in underlying assumptions. Scenario analysis showed even more cost savings with targeted screening for women less than 30 years of age or with first pregnancies only. Antenatal screening for C. trachomatis is a cost-saving intervention when testing all pregnant women in the Netherlands. Savings increase even further when testing women younger than 30 years of age or with pregnancies only