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Factors influencing the infectivity of Chlamydia pneumoniae elementary bodies on HL cells
J J Theunissen1, B Y van Heijst, J H Wagenvoort
1Department of Dermato-Venereology, Erasmus University, Rotterdam, The Netherlands.
Abstract:
The influence of variations in the pH, NaCl concentration, temperature, and concentrations of calcium and magnesium ions on the survival of Chlamydia pneumoniae elementary bodies (EBs) outside the host cells was investigated. The survival was determined after various incubation periods by counting the inclusion-forming units after C. pneumoniae was cultured for 72 h on monolayers of HL cells. The normal physiological conditions were restored prior to infecting the HL cells with C. pneumoniae. Declines in the infectivities of C. pneumoniae EBs were observed at pH values of lower than 5 and higher than 8 or at NaCl concentrations of less than 80 mM. The viability of C. pneumoniae EBs in SPG medium decreased as the temperature and/or incubation period increased. Incubation temperatures of up to 20 degrees C and incubation periods of up to 48 h did not affect the viability of C. pneumoniae. One hundred percent of the C. pneumoniae EBs were infective after 1 h of incubation at 35 degrees C, whereas 90, 50, and 40% survived after incubations of 8, 24, and 48 h, respectively. The viability of C. pneumoniae was unaffected within the investigated range of Ca2+ and Mg2+ ion concentrations in the medium. The presence of 10% fetal calf serum in the incubation medium had a stabilizing effect on the viability of C. pneumoniae. This effect became more pronounced as the incubation period increased.
Insights
Chlamydia pneumoniae elementary bodies (EBs) survival is sensitive to environmental factors. Maintaining pH, NaCl, and temperature is crucial for EB viability outside host cells.
Area of Science:
- Microbiology
- Infectious Diseases
- Bacteriology
Background:
- Chlamydia pneumoniae is an important human pathogen.
- Understanding the survival of elementary bodies (EBs) outside host cells is critical for infection control.
- Environmental factors can significantly impact pathogen viability.
Purpose of the Study:
- To investigate the influence of environmental factors on Chlamydia pneumoniae EB survival.
- To determine the optimal conditions for maintaining C. pneumoniae EB infectivity outside the host.
Main Methods:
- Chlamydia pneumoniae EBs were incubated under various conditions (pH, NaCl, temperature, Ca2+, Mg2+).
- Survival was assessed by quantifying inclusion-forming units (IFUs) after co-culturing with HL cells.
- Incubation periods and temperatures were systematically varied.
Main Results:
- C. pneumoniae EB infectivity declined at pH < 5 or > 8, and NaCl < 80 mM.
- Viability decreased with increasing temperature and incubation time; 40% survival after 48h at 35°C.
- Ca2+ and Mg2+ concentrations did not affect viability within the tested range.
- 10% fetal calf serum stabilized EB viability, especially over longer incubation periods.
Conclusions:
- Chlamydia pneumoniae EB survival is significantly influenced by pH, NaCl concentration, and temperature.
- Specific environmental conditions are required to maintain C. pneumoniae EB infectivity.
- Fetal calf serum can enhance the stability and viability of C. pneumoniae EBs.