Colonization of healthy children by Moraxella catarrhalis is characterized by genotype heterogeneity, virulence gene diversity and co-colonization with Haemophilus influenzae.
The colonization dynamics of Moraxella catarrhalis were studied in a population comprising 1079 healthy children living in Rotterdam, The Netherlands (the Generation R Focus cohort). A total of 2751 nasal swabs were obtained during four clinic visits timed to take place at 1.5, 6, 14 and 24 months of age, yielding a total of 709 M. catarrhalis and 621 Haemophilus influenzae isolates. Between January 2004 and December 2006, approximate but regular 6-monthly cycles of colonization were observed, with peak colonization incidences occurring in the autumn/winter for M. catarrhalis, and winter/spring for H. influenzae. Co-colonization was significantly more likely than single-species colonization with either M. catarrhalis or H. influenzae, with genotypic analysis revealing no clonality for co-colonizing or single colonizers of either bacterial species. This finding is especially relevant considering the recent discovery of the importance of H. influenzae-M. catarrhalis quorum sensing in biofilm formation and host clearance. Bacterial genotype heterogeneity was maintained over the 3-year period of the study, even within this relatively localized geographical region, and there was no association of genotypes with either season or year of isolation. Furthermore, chronological and genotypic diversity in three immunologically important M. catarrhalis virulence genes (uspA1, uspA2 and hag/mid) was also observed. This study indicates that genotypic variation is a key factor contributing to the success of M. catarrhalis colonization of healthy children in the first years of life. Furthermore, variation in immunologically relevant virulence genes within colonizing populations, and even within genotypically identical M. catarrhalis isolates, may be a result of immune evasion by this pathogen. Finally, the factors facilitating M. catarrhalis and H. influenzae co-colonization need to be further investigated.
Verhaegh
Suzanne J C
SJC
The Generation R Study Group, Erasmus MC, Rotterdam, The Netherlands.|Department of Medical Microbiology and Infectious Diseases, Erasmus MC, Rotterdam, The Netherlands.
Snippe
Martine L
ML
Department of Medical Microbiology and Infectious Diseases, Erasmus MC, Rotterdam, The Netherlands.
Levy
Foster
F
Department of Biological Sciences, East Tennessee State University, Johnson City, TN, USA.
Verbrugh
Henri A
HA
Department of Medical Microbiology and Infectious Diseases, Erasmus MC, Rotterdam, The Netherlands.
Jaddoe
Vincent W V
VWV
Department of Epidemiology, Erasmus MC, Rotterdam, The Netherlands.|Department of Pediatrics, Erasmus MC, Rotterdam, The Netherlands.|The Generation R Study Group, Erasmus MC, Rotterdam, The Netherlands.
Hofman
Albert
A
Department of Epidemiology, Erasmus MC, Rotterdam, The Netherlands.|The Generation R Study Group, Erasmus MC, Rotterdam, The Netherlands.
Moll
Henriëtte A
HA
Department of Pediatrics, Erasmus MC, Rotterdam, The Netherlands.
van Belkum
Alex
A
Department of Medical Microbiology and Infectious Diseases, Erasmus MC, Rotterdam, The Netherlands.
Hays
John P
JP
Department of Medical Microbiology and Infectious Diseases, Erasmus MC, Rotterdam, The Netherlands.
D015373:Bacterial Typing Techniques; D002353:Carrier State / Q000382:microbiology*; D002675:Child, Preschool; D014644:Genetic Variation; D005838:Genotype; D006192:Haemophilus Infections / Q000382:microbiology*; D006193:Haemophilus influenzae / Q000302:isolation & purification*; D006805:Human Experimentation; D006801:Humans; D007223:Infant; D001936:Moraxella catarrhalis / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000472:pathogenicity; D045828:Moraxellaceae Infections / Q000382:microbiology*; D058885:Multilocus Sequence Typing; D009426:Netherlands; D009666:Nose / Q000382:microbiology; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics*
D037521:Virulence Factors