Age-related genotypic and phenotypic differences in Moraxella catarrhalis isolates from children and adults presenting with respiratory disease in 2001–2002

Abstract

Moraxella catarrhalis is generally associated with upper respiratory tract infections in children and lower respiratory tract infections in adults. However, little is known regarding the population biology of isolates infecting these two age groups. To address this, a population-screening strategy was employed to investigate 195 worldwide M. catarrhalis isolates cultured from children (,5 years of age) and adults (.20 years of age) presenting with respiratory disease in the years [2001][2002]. Parameters compared included: genotype analysis; autoagglutination/biofilmforming ability; serum resistance; uspA1, uspA2, uspA2H, hag and mcaP incidence; copB/LOS/ ompCD/16S rRNA types; and UspA1/Hag expression. A significant difference in biofilm formation (P50.002), but not in autoagglutination or serum resistance, was observed, as well as significant differences in the incidence of uspA2-and uspA2H-positive isolates, and the distribution of lipooligosaccharide (LOS) types (P,0.0001 and P50.01, respectively). Further, a significant decrease in the incidence of Hag expression (for isolates possessing the hag gene) was observed in adult isolates (P50.001). Both uspA2H and LOS type B were associated with 16S rRNA type 1 isolates only, and two surrogate markers (copB and ompCD PCR RFLP types) for the two major M. catarrhalis 16S rRNA genetic lineages were identified. In conclusion, there are significant differences in phenotype and gene incidence between M. catarrhalis isolates from children and adults presenting with respiratory disease, possibly as a result of immune evasion in the adult age group. Our results should also be useful in the choice of effective vaccine candidates against M. catarrhalis.

Colonization of healthy children by Moraxella catarrhalis is characterized by genotype heterogeneity, virulence gene diversity and co-colonization with Haemophilus influenzae

“…However, complement-evading systems, e.g. via OMV-mediated protection, may also play a significant role.Genotypic analysis revealed a high degree of diversity in colonizing M. catarrhalis isolates, an observation which is in agreement with previous studies showing that genotypic heterogeneity is typical of worldwide M. catarrhalis isolates colonizing both children and adults (Hays et al, 2003;Verhaegh et al, 2008;Wolf et al, 2000). Also, no significant association between genotype (cluster) and season, or year of isolation was observed, which is in contrast with a previous publication by Levy et al (2009) relatively confined hospital setting (Levy et al, 2009), whereas the focus of our study was related to community transmission.…”

“…All isolates negative for both uspA2 and uspA2H genes were tested using primers uspA2end.f and uspA2end (Verhaegh et al, 2008), which amplify a conserved region found at the 39-end of both uspA2 and uspA2H genes.…”

Temporal development of the humoral immune response to surface antigens of Moraxella catarrhalis in young infants

“…To identify the 16S rRNA types of individual M. catarrhalis isolates, 16S rRNA PCR products were digested using the enzymes FspBI (10 U) and HhaI (10 U) according to Verhaegh et al (2008) [19]. seconds during the first 12 hours, followed by a 2nd block of 8 hours where the pulse time increased linearly from 1 to 5 seconds.…”

“…Briefly, after used [19]. The uspA2, uspA2H and uspA1 screening primers are situated at the 3'-end of the respective genes, whilst the hag/mid primers amplify a region at the 5'-end of the gene, including a small region of the promotor.…”

“…Further, PCR was performed to detect 16S rRNA types as previously described by Verhaegh et al (2008) [19].…”