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Parachlamydia and Rhabdochlamydia in respiratory secretions of premature newborns: prevalence and clinical impact

Abstract number: O468

Lamoth F., Schneider A., Aeby S., Jaton K., Vaudaux B., Greub G.

Objectives:Parachlamydia acanthamoebae is a new recognized member of the order Chlamydiales. Growing evidences suggest that this bacteria may have a pathogenic role in humans causing respiratory diseases. It has also been recently identified as an agent of bovine abortion and may be a cause of miscarriage in women. In contrast, little is known about the pathogenic role of Rhabdochlamydia crassificans, another related Chlamydiales. Molecular diagnostic tools are useful to detect these obligate intracellular bacteria because of their inability to grow on conventional culture media. The aim of this work was (i) to develop a real-time PCR for the diagnosis of Rhabdochlamydia infection and (ii) to study respiratory secretions of newborns for the presence of Parachlamydia and Rhabdochlamydia DNA.

Methods: A new quantitative real-time TaqMan PCR (q-PCR) to be used on ABI Prism 7900 was developed. The q-PCR was then blindly applied to 41 consecutive respiratory samples (endotracheal or nasopharyngeal secretions) taken from 29 critically-ill newborns admitted in the neonatology ward of our university hospital. These samples were also tested using a previously developed Parachlamydia-specific PCR.

Results: Most newborns (28/29) were premature (median gestational age: 28.6 weeks; range: 24.6–41.2). Initial respiratory distress syndrome was present in 86% of them. Positive PCR results were obtained in 12/29 (41%) patients (8 Parachlamydia, 3 Rhabdochlamydia, 1 both species) at a median of 17.5 days (range: 2–230) after birth. When compared to the control group (17 patients with negative PCR), these 12 newborns had a significantly worse primary adaptation and a higher incidence of resuscitation maneuvers at birth (Table). Duration of non-invasive mechanical ventilation and stay in neonatology ward were also significantly longer. A fatal issue was observed in 3 infected cases, as compared to no death in controls (p = 0.06). Gestational age at birth as well as the incidence of pulmonary or systemic infections did not differ between cases and controls.

Conclusion: A high prevalence of Parachlamydia and Rhabdochlamydia DNA was observed in respiratory secretions of premature critically-ill newborns. The presence of DNA of these microorganisms was associated with a worse primary adaptation, a more severe respiratory distress syndrome and a trend towards a higher mortality. Their pathogenic role should be further investigated.

Table. Newborns with positive PCR for Parachlamydia and/or Rhabdochlamydia in respiratory secretions compared with control group

 Positive results (n = 12)Negative results (n = 17)P value
Primary adaptation (Apgar score)   
  First score (1 min)*2.5 (0–7)8 (2–9)0.002
  Sum of 3 scores (1, 5, 10 min)*18.5 (8–27)27 (17–29)0.002
Cardiac resuscitation (first 48 h)**6 (50)0 (0)0.002
Invasive mechanical ventilation (first 48 h)**11 (92)8 (47)0.019
*median (range); **total number (percent).

Session Details

Date: 16/05/2009
Time: 00:00-00:00
Session name: 19th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Helsinki, Finland, 16 - 19 May 2009
Presentation type:
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