Coagulase and protein A polymorphisms do not contribute to persistence of nasal colonisation by Staphylococcus aureus

Abstract

The nasal carriage rate of Staphylococcus aureus was examined in a longitudinal study of 31 healthy Danish volunteers. Each person was classified as persistent (>8 positive cultures from 10 examinations), an intermittent carrier (50-80% positive cultures) or an ocassional carrier (positive cultures on 10--40% of ocassions only). One hundred and twenty strains from these persons were subjected to phage typing and random amplification of polymorphic DNA (RAPD) analysis. Phage and RAPD typing were in close agreement. RAPD confirmed the spread of a particular S. aureus clone (phage type 95) throughout Denmark. However, no common genotype or phenotype characteristics of S. aureus that could separate persistent from intermittent or incidental colonisers were identified. The immunoglobulin binding protein A and the prothrombin binding coagulase protein are both putative S. aureus virulence or defence factors. Analysis of polymorphisms in the variable repeat regions in the genes for these proteins showed no correlation between the number of repeat units and, consequently, the protein structure with the ability of strains to persist in the human nasal mucosa. The amount of protein A, detectable by its IgG binding activity, appeared not to be correlated to persistence of carriage. Thus protein A and coagulase gene polymorphisms do not seem to play a significant role in the propensity of S. aureus to colonise human nasal epithelium. Furthermore, based on the genetic heterogeneity encountered among the S. aureus strains it is suggested that within the current study population, no single clonal lineage of S. aureus has increased capability to colonise the human nasal epithelium.

Molecular Epidemiology of Methicillin-Resistant Staphylococcus aureus in Finland

“…A longer X-region in epidemic strains may result in a better exposition of the Fc-binding region of protein A (81). Another study did not support this hypothesis, since no correlation was found between the length of the protein A gene repeats and the persistence of S. aureus colonization (279). In the light of the present and previous studies and the fact that S. aureus colonization and virulence result from a complicated interplay of numerous factors, it seems that no single mechanism is responsible for the successful transmission of certain clones.…”

Clearance of Staphylococcus aureus Nasal Carriage Is T Cell Dependent and Mediated through Interleukin-17A Expression and Neutrophil Influx

“…There is evidence that colonization is strain dependent, as persistence can be caused by a single S. aureus strain (5), compared to presence of genetically unrelated strains over time in intermittently colonized patients (6). Carriage may also be dependent upon the presence of certain commensal bacteria in the nares.…”

Staphylococcus aureusandStreptococcus pneumoniaeinteraction and response to pneumococcal vaccination: Myth or reality?

“…51 In contrast, S. aureus appears to elicit a futile antibody response, allowing the bacteria to escape immune responses and recurrent colonization and infections with S. aureus are common. [52][53][54] Moreover, »20% of healthy adult individuals are persistent carriers of a single strain for many years, 55,56 while young healthy adults are typically carriers of S pneumoniae only for very short durations, even following experimental exposures. 57 Shak et al showed that when S. aureus carriers were artificially inoculated with S. pneumoniae, successful colonization resulted in a decrease in S. aureus carriage, but only 14 d later.…”