Join Date: May 2005
Location: Edmonton, AB Canada
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|Why are there so many serotypes of proteins that cause blood coagulation? From our results, we presume that antigenic variation in staphylocoagulases might be useful to evade the host immune response and/or to adapt to the different staphylocoagulase-prothrombin binding sites of mammalian species. Vaccines against the type b capsular polysaccharides of Haemophilus influenzae (Hib) have been used to reduce the incidence of invasive diseases caused by H. influenzae in industrial countries. However, as the use of the vaccines increased, the number of non-Hib strains in clinical isolates has also increased (29, 33, 49). The possibility of “serotype replacement” has been raising concerns. It can be postulated that staphylocoagulases changed their antigenicities by altering amino acids to evade the host defense system.|
|However, immunization can also place
selective pressure on the nasopharyngeal flora, promoting the
emergence of new pathogens. A shift towards non-vaccineserotypes has been observed among vaccinees in several studies.
109 In South Africa, the carriage of non-vaccine serotypes
was increased from 24% in controls to 36% in the vaccines
group. A significant increase was seen in the carriage of
serotypes 7 and 15, important causes of invasive disease.109
|A trial with a 7-valent pneumococcal-conjugate vaccine in children with recurrent acute otitis media showed a shift In pneumococcal colonisation towards non-vaccine serotypes and an Increase In Staphylococcus aureus-related acute otitis media after vaccination. We investigated prevalence and determinants of nasopharyngeal carriage of Streptococcus pneumonlae and S aureus in 3198 healthy children aged 1-19 years. Nasopharyngeal carriage of S pneumonlae was detected In 598 (19%) children, and was affected by age (peak Incidence at 3 years) and day-care attendance (odds ratio [OR] 2.14, 95% Cl 1.44-3.18). S aureus carriage was affected by age (peak incidence at 10 years) and male sex (OR 1.46, 1.25-1.70). Serotyping showed 42% vaccine type pneumococci. We noted a negative correlation for co-colonisation of S aureus and vaccine-type pneumococci (OR 0.68, 0.48-0.94), but not for S aureus and non-vaccine serotypes. These findings suggest a natural competition between colonisation with vaccine-type pneumococci and S aureus, which might explain the Increase in S aureus-related otitis media after vaccination.|
|FINDINGS: We noted no reduction of AOM episodes in the pneumococcal vaccine group compared with controls (intention-to-treat analysis: rate ratio 1.25, 95% CI 0.99-1.57). Although nasopharyngeal carriage of pneumococci of serotypes included in the conjugate-vaccine was greatly reduced after pneumococcal vaccinations, immediate and complete replacement by non-vaccine pneumococcal serotypes took place.|
Man, that Hib and the pneumococcal vax sure cause a lot of problems.
I LIKE that ScholarGoogle.
All I typed in was "vaccines and serotype replacement" and WOW!
Wow-That's interesting. I have just returned from the hospital where my dd spent a whole week getting an egg sized lump removed caused by staph infection. I vaxed her up until 6 months. She is 9 months now and the doctor told me that this lump on her neck probaly started growing a few months ago. The thought that a vax caused it crossed my mind several times. The doctors told me that staph infections are common and found on the skin. I have stopped vaxing her because of my guilt and confusion about the medical industry and who's best interest they have in mind. Thanks for posting this thread...very interesting.
THe doctor told me that there's a specific staph that is like a "mutant staph" and certain antibiotics cannot get rid of it. She also told that she is seeing staph a lot lately. hmmm.
|Prevnar was introduced in 2001, and you can see that "overall cases of bacterial meningitis" in kids under 2 has actually gone UP since then.|
|The bactericidal activity of Streptococcus pneumoniae toward Staphylococcus aureus is mediated by hydrogen peroxide. Catalase eliminated this activity. Pneumococci grown anaerobically or genetically lacking pyruvate oxidase (SpxB) were not bactericidal, nor were nonpneumococcal streptococci. These results provide a possible mechanistic explanation for the interspecies interference observed in epidemiologic studies.|
Among 790 children screened, 43% carried S pneumoniae and 10% carried S aureus. Staphylococcus aureus carriage among S pneumoniae carriers was 6.5% vs 12.9% in S pneumoniae noncarriers. Streptococcus pneumoniae carriage among S aureus carriers was 27.5% vs 44.8% in S aureus noncarriers. Only 2.8% carried both pathogens concomitantly vs 4.3% expected dual carriage (P = .03). Risk factors for S pneumoniae carriage (attending day care, having young siblings, and age older than 3 months) were negatively associated with S aureus carriage.
Streptococcus pneumoniae carriage, specifically of vaccine-type strains, is negatively associated with S aureus carriage in children. The implications of these findings in the pneumococcal vaccine era require further investigation.
|If the association is causal and acquisition of S. pneumoniae eradicates S. aureus carriage, then use of pneumococcal vaccines may eliminate the “protective” effect of S. pneumoniae against S. aureus carriage and an increase in S. aureus carriage will follow. Increased S. aureus otitis media has been observed among vaccinees in a pneumococcal conjugate vaccine randomized trial (23). Whether the current increase in severe community-acquired S. aureus infections, including methicillin-resistant S. aureus (6), is partially caused by the recent introduction of the pneumococcal conjugate vaccine is yet to be determined.|
|Pneumococcal conjugate vaccines
reduce nasopharyngeal carriage of vaccine-
type S pneumoniae. Our finding of
an inverse relationship between vaccinetype
S pneumoniae and S aureus may imply
an upcoming shift, not only toward
nonvaccine S pneumoniae serotypes17 but
also toward higher S aureus carriage rates
in children. This would be particularly
disturbing in light of the emergence of
S aureus.5,6,18 This possibility is
supported by a recent report of an increased
rate of S aureus culturepositive
draining ears in vaccinated children
compared with controls.
|Our study suggests a protective role
of S pneumoniae carriage against S aureus
carriage. Studies measuring the
effect of vaccination on S pneumoniae
epidemiology should also examine concurrent
changes in S aureus.
The heptavalent pneumococcal conjugate vaccine (PCV7) has been shown to reduce the incidence of acute otitis media (AOM) caused by Streptococcus pneumoniae by 34% and reduces the overall incidence of AOM by 6% to 8%.
More recent studies have shown increases in the proportion of Haemophilus influenzae and Moraxella catarrhalis in the middle-ear fluid of PCV7-immunized children. There has been no report on the effect of PCV7 on all 3 bacterial pathogens combined, either in the middle-ear fluid or nasopharynx of individual children with AOM. We investigated the impact of PCV7 on nasopharyngeal colonization with bacterial pathogens during AOM in the pre-PCV7 and post-PCV7 vaccination eras. Four hundred seventeen children (6 months to 4 years of age) were enrolled onto AOM studies between September 1995 and December 2004. Of these, 200 were enrolled before the vaccine use (historical controls), and 217 were enrolled after the initiation of PCV7 vaccination (101 were underimmunized, and 116 were immunized). Although the nasopharyngeal colonization rate for S pneumoniae was not different between the 3 groups, a significantly higher proportion of PCV7-immunized children with AOM were colonized with M catarrhalis. Overall, the mean number of pathogenic bacteria types isolated from immunized children (1.7) was significantly higher than in controls (1.4). The increase in bacterial colonization of the nasopharynx during AOM could be associated with an increase in AOM pathogens and theoretically can predispose PCV7-immunized children with AOM to a higher rate of antibiotic treatment failure or recurrent AOM.
|The rates of invasive pneumococcal disease (IPD), serotype distribution and antimicrobial susceptibility prior to and after the introduction of the heptavalent pneumococcal conjugate vaccine in Portuguese children were evaluated. The changes in incidence of IPD in children under 1 year old between the two periods of the study was not significant (P=0.53), despite the 21% decline. In children under 18 years old there was a 27.7% decrease in vaccine serotypes. All nonvaccine serotypes increased 71.4%. The decrease in vaccine serotypes was more impressive during the first year of life (−54.8%) than for children between 1 and 5 years of age (−19.1%). Among children under 1 year old, penicillin nonsusceptible isolates declined between the two periods of the study (47.2% vs. 25.0%) (P=0.03), as did those of cefotaxime and ceftriaxone nonsusceptible isolates. No changes were observed for isolates nonsusceptible to tetracycline and macrolides. The serotypes of these nonsusceptible isolates differed after the introduction of vaccine (P=0.01). Multiresistance increased 57.1% after the introduction of vaccine. Multiresistant isolates with vaccine serotype declined 42.9% (P<0.001), and nonvaccine serotypes appeared during the vaccination period (P<0.001). These findings suggest a replacement of vaccine serotypes by nonvaccine serotypes, mainly among nonsusceptible isolates.|