[Adaptation mechanisms in the formation of the Corynebacterium diphtheriae carrier state]

Area of Science:

• Microbiology
• Immunology
• Pediatrics

Background:

• Diphtheria remains a public health concern, with asymptomatic carrier states complicating control efforts.
• Understanding the factors influencing the persistence of toxigenic Corynebacterium diphtheriae (TCD) in carriers is crucial for effective management.

Purpose of the Study:

• To investigate the relationship between microbial virulence factors of TCD strains and host immune responses in children with a carrier state.
• To identify key factors determining the duration of TCD persistence in pediatric carriers.

Main Methods:

• Clinico-laboratory examination of 92 children (3-14 years) with localized stomatopharyngeal diphtheria and TCD carrier state.
• Assessment of TCD strain properties: hydrophobic properties, adhesion, lysozyme, antilysozyme, and DNAase activities.
• Evaluation of host immunity: specific and nonspecific immunity, including humoral specific antibacterial immunity and local IgA.

Main Results:

• Bacterial colonization activity significantly influences the infectious process in TCD carriers.
• Direct correlation observed between TCD persistence duration and bacterial hydrophobic properties, adhesive, and antilysozyme activities (r = 0.89-0.93).
• Inverse relationship found between TCD carrier state duration and epithelial cell electrophysiology, humoral specific immunity, and local IgA levels.

Conclusions:

• The duration of TCD carrier state in children is significantly influenced by the interplay between bacterial virulence factors and the host's immune status.
• Enhanced bacterial adhesion and antilysozyme activity, coupled with diminished host immunity, contribute to prolonged TCD carriage.