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Bacterial
carriage in human nasopharynx: selected molecular aspects
Abstract: many
humans are symptomless carriers of such potentially pathogenic
bacteria as Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae
and Moraxella (Branhamella)
catarrhalis. The frequency of carriage rates varies greatly
among people, showing dependency from age, season, living
conditions and opportunity to contact the carriers by a given
person. Human organisrn possesses several mechanisms that counteract
microbial colonization. To successfully colonize, bacteria must
adhere to host epithelial cells, evade the activity of immune
system and acquire nutrients indispensable for their growth.
As human nasopharynx can host several strains and bacterial
species, it is also a place of frequent genetic exchange and
various interactions among microorganisms, both symbiotic and antagonistic
in nature. The recent developments in genomics and related
approaches already have contributed and soon will lead to better
understanding the phenomena occurring during the carriage and
factors promoting transition to the disease state.
1. Introduction.
2. Factors influencing bacterial carriage in humans. 3. Bacterial
adhesion to host cells. 3.1. Adhesion factors:
Gram-negative bacteria. 3.2. Adhesion factors: pneumococci.
4. Interference with the clearance activity of respiratory
tract cilia. 5. Acquisition of nutrients. 6. Evasion of host
immunological system. 7. Regulation of expression of the
genes involved in colonization. 8. Communication within
populations of colonizing bacteria and genetic material
exchange. 9. Mutual relationships among species: symbiosis
and antagonism. 10. Nasopharyngeal carriage and development
of a disease. 11. Summary |
