Direct and Indirect Effectiveness of the 10-Valent Pneumococcal Conjugate Vaccine Against Carriage in a Cluster Randomized Trial.

Finnish invasive pneumococcal disease (FinIP) vaccine trial was designed to evaluate effectiveness of 10-valent pneumococcal conjugate vaccine (PHiD-CV10; GSK; Rixensart, Belgium). We conducted 2 satellite studies to evaluate ten-valent Pneumococcal Haemophilus influenzae protein D conjugate vaccine (PHiD-CV10) effectiveness against pneumococcal carriage in FinIP-vaccinated children (long-term direct and indirect effectiveness combined) and in their unvaccinated siblings (indirect effectiveness within the family). FinIP was a cluster randomized trial, where >47,000 children <19 months of age were recruited in 2009-2010. Children received PHiD-CV10 in 2/3, and control vaccine in 1/3 of clusters according to age-specific infant and catch-up schedules. We obtained nasopharyngeal samples from subgroups of FinIP-vaccinated children at 3-5 years of age in 2013 and their unvaccinated older siblings in 2011 and 2013, and compared carriage in PHiD-CV10 clusters to control clusters in parallel. National Vaccination Programme with PHiD-CV10 for all 3-month-old children started in 2010 resulting in 92% vaccination coverage. To investigate indirect effects, over 2200 nasopharyngeal swabs were obtained during each round from unvaccinated older siblings. In 2011, we observed a 29% (95% confidence interval: 6-47) reduction in vaccine-type carriage in siblings of PHiD-CV10 participants vaccinated according to infant schedules. Vaccine-type carriage prevalences were low with no differences observed in 2013, 3 years after PHiD-CV10 introduction. For estimation of combined direct and indirect effectiveness, 1550 swabs from FinIP-vaccinated children were obtained in 2013. We observed a reduction of 54% (95% confidence interval: 34-68) in vaccine-type carriage in PHiD-CV10-vaccinated children. This study was the first randomized trial to show the indirect effect of extended valency pneumococcal conjugate vaccination on carriage. Also, long-term effectiveness against vaccine-type carriage was demonstrated in vaccinated children.

Effectiveness of the 10-Valent Pneumococcal Nontypeable Haemophilus influenzae Protein D-Conjugated Vaccine (PHiD-CV) Against Carriage and Acute Otitis Media-A Double-Blind Randomized Clinical Trial in Finland.

UNLABELLED: After administering the 10-valent pneumococcal polysaccharide nontypeable Haemophilus influenzae protein D-conjugated vaccine (PHiD-CV) to children aged 2-18 months, we observed a reduction in vaccine-type nasopharyngeal carriage, resulting in a reduction of overall pneumococcal nasopharyngeal carriage, which may be important for indirect vaccine effects. We noted a trend toward reduction of acute otitis media. BACKGROUND: This trial (ClinicalTrials.gov identifier NCT00839254), nested within a cluster-randomized double-blind invasive pneumococcal disease effectiveness study in Finland (ClinicalTrials.gov identifier NCT00861380), assessed the effectiveness of the 10-valent pneumococcal polysaccharide nontypeable Haemophilus influenzae protein D-conjugated vaccine (PHiD-CV or PCV10) against bacterial nasopharyngeal carriage and acute otitis media (AOM). METHODS: Infants (aged 6 weeks to 6 months) received the PHiD-CV or a control vaccine (hepatitis B) (schedule 3+1 or 2+1). Nasopharyngeal swabs were collected at 4 time points post-vaccination from all of the infants and at pre-vaccination from a subset. Parent-reported physician-diagnosed AOM was assessed from first vaccination until last contact (mean follow-up, 18 months). Vaccine effectiveness (VE) was derived as (1 - relative risk)*100, accounting for cluster design in AOM analysis. Significant VE was assessed descriptively (positive lower limit of the non-adjusted 95% confidence interval [CI]). RESULTS: The vaccinated cohort included 5093 infants for carriage assessment and 4117 infants for AOM assessment. Both schedules decreased vaccine-serotype carriage, with a trend toward a lesser effect from the 2+1 schedule ( VE across timpoints 19%-56% [3+1] and 1%-38% [2+1]). Trends toward reduced pneumococcal carriage (predominantly vaccine serotypes 6B, 14, 19F, and 23F), decreased carriage of vaccine-related serotype 19A, and small increases at later time points (ages 14-15 months) in non-vaccine-serotype carriage were observed. No effects on nontypeable Haemophilus influenzae, Staphylococcus aureus, or Moraxella catarrhalis carriage were observed. There were non-significant trends toward a reduction in the number of infants reporting AOM episodes (VE 3+1: 6.1% [95% CI, -2.7% to 14.1%] and 2+1: 7.4% [-2.8% to 16.6%]) and all AOM episodes (VE 3+1: 2.8% [-9.5% to 13.9%] and 2+1: 10.2% [-4.1% to 22.9%]). PHiD-CV was immunogenic and had an acceptable safety profile. CONCLUSIONS: We observed reduced vaccine-type pneumococcal carriage, a limited increase in non-vaccine-type carriage, and a trend toward AOM reduction.

Long-term survival of Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis as isolates and in nasopharyngeal specimens in frozen STGG storage medium.

We evaluated survival in WHO-recommended STGG storage medium of bacteria causing respiratory-tract infection. Streptococcus pneumoniae and Moraxella catarrhalis survived as single and mixed isolates stored at -70°C for 12.5 years, but Haemophilus influenzae less than 4 years. All the bacteria survived in the nasopharyngeal specimens at -70°C for 11 years.

Efficacy of the 7-Valent Pneumococcal Conjugate Vaccine Against Acute Otitis Media Caused by Serotype 6C Pneumococcus.

A new pneumococcal serotype 6C, earlier typed as 6A, was discovered in 2007. We retyped all 6A isolates to evaluate vaccine efficacy against 6C acute otitis media (AOM) in the phase III randomized, double-blind Finnish Otitis Media trial conducted in 1995-1999. Efficacy against 6C AOM was -1 (95% confidence interval: -248 to 71) during the per protocol follow-up period. The updated vaccine efficacy estimate for serotype 6A AOM was 65% (95% confidence interval: 31-82). Seven-valent pneumococcal conjugate vaccine offered excellent cross-protection against 6A AOM, but our data do not support cross-protection against 6C AOM.

Diet as a risk factor for pneumococcal carriage and otitis media: a cross-sectional study among children in day care centers.

BACKGROUND: Pharyngeal bacteria are exposed to different sugar conditions depending on the diet of the child. We hypothesized that dietary factors such as daily intake of carbohydrates could be associated with pneumococcal carriage and the occurrence of otitis media in children. METHODS: Our study design was a cross-sectional study among 1006 children attending child day care centers. Parents filled in a food frequency questionnaire. Oropharyngeal swabs were collected from each child. The primary outcome was the occurrence of pneumococcal carriage and the secondary outcome the number of acute otitis media episodes during life. Principal component analysis was used to group dietary intake into nine factors. The models were adjusted for age, gender of the child and educational level of the mother. RESULTS: The dietary factor which included high consumption of sweet pastries and jam was associated with an increased risk of pneumococcal carriage (OR 1.17, 95% CI 1.01 to 1.36, P-value 0.04). The factor including frequent consumption of fruit and berries was associated with a decreased risk of acute otitis (regression coefficient -0.51, 95% CI -0.98 to -0.03, P=0.04). A high intake of consumption of sweets and snacks (OR 1.36, 95% CI 1.03 to 1.80, P=0.03) was associated with an increased risk of caries. CONCLUSIONS: Diet was associated with a risk of pneumococcal carriage and the occurrence of otitis media. Diet may thus be a modifiable risk factor for the occurrence of acute otitis media.

Incidence and etiology of community-acquired pneumonia in the elderly in a prospective population-based study.

BACKGROUND: We conducted a prospective population-based epidemiological study to prepare a setting for documentation of the efficacy of novel vaccines against pneumococcal (Pnc) community-acquired pneumonia (CAP) in the elderly. Specific objectives were to demonstrate setting feasibility, to construct a case definition for Pnc CAP, and to estimate its incidence. METHODS: We prospectively enrolled patients with clinical and radiological findings compatible with CAP at municipal on-call clinics serving an elderly population (age ≥ 65 y) of approximately 29,500. Sputum, urine, nasopharyngeal swab (NPS), and blood samples were analyzed using diverse methods for the identification of Pnc (culture, PCR, antigen tests, serology) and of other pathogens. The following case definition for Pnc CAP was derived: encapsulated Pnc in blood culture or in high-quality sputum culture or at least 2 of the following: positive urine Pnc antigen; ≥ 2-fold increase in serum anti-PsaA or anti-CbpA antibodies; encapsulated Pnc culture or LytA PCR in either sputum or NPS. RESULTS: We enrolled 490 clinical CAP patients during the 2-y follow-up, 53% of all clinical CAP patients in the source population; 323 were radiologically confirmed. The incidence of radiologically confirmed CAP was 5.5/1000 person-y (95% confidence interval (CI) 4.9-6.1) and 10.5/1000 person-y when adjusted for non-captured patients. The proportion of radiologically confirmed CAP caused by Pnc was estimated at 17%; i.e. 0.95/1000 person-y (95% CI 0.7-1.2) and 1.8 when adjusted for non-captured patients. CONCLUSIONS: We developed and documented a feasible methodology for capturing endpoints in a vaccine trial for the prevention of pneumonia. CAP incidence in the elderly population remains considerable and Streptococcus pneumoniae was one of the most commonly detected causative agents.

Antimicrobial resistance in relation to sero- and genotypes among invasive Streptococcus pneumoniae in Finland, 2007-2011.

AIM: We studied the serotypes and antimicrobial resistance of the invasive Streptococcus pneumoniae that had been isolated in Finland during 5 years. The 10-valent vaccine was introduced into the National Vaccination Programme in September 2010. METHODS: We examined the antimicrobial resistance and serotype distribution of the invasive pneumococci (n=4,194) that had been isolated in Finland during 2007-2011. The penicillin-resistant (PEN R) (≥4 mg/L) isolates (n=12) were genotyped by MLST. RESULTS: Serotype 14 was consistently the most prominent serotype, covering 18.0-20.1% of all the isolates. The proportion of serotypes 3, 19A, and 22F increased significantly, while that of 6B and the PCV10 vaccine serotypes combined decreased. PEN nonsusceptibility (≥0.12 mg/L) increased, ranging from 14.4% to 23.2% by year, and was the highest (28.5%) among the 0-2 year olds. The PEN and/or erythromycin (ERY) nonsusceptibility of several vaccine serotypes (4, 6B, 14, and 19F) increased significantly over the study period. The ERY nonsusceptibility was 26.6%. There was limited diversity among the PEN R isolates; all were a part of serotype 19F, 19A, or 14, and two globally disseminated genetic lineages carrying one or both pilus-encoding islets. CONCLUSIONS: High and/or increasing nonsusceptibility rates underline the importance of monitoring the serotype distribution and antimicrobial susceptibility of pneumococci, especially after large-scale vaccination.

Comparative analysis of Streptococcus pneumoniae transmission in Portuguese and Finnish day-care centres.

BACKGROUND: Day-care centre (DCC) attendees play a central role in maintaining the circulation of Streptococcus pneumoniae (pneumococcus) in the population. The prevalence of pneumococcal carriage is highest in DCC attendees but varies across countries and is found to be consistently lower in Finland than in Portugal. We compared key parameters underlying pneumococcal transmission in DCCs to understand which of these contributed to the observed differences in carriage prevalence. METHODS: Longitudinal data about serotype-specific carriage in DCC attendees in Portugal (47 children in three rooms; mean age 2 years; range 1-3 years) and Finland (91 children in seven rooms; mean age 4 years; range 1-7 years) were analysed with a continuous-time event history model in a Bayesian framework. The monthly rates of within-room transmission, community acquisition and clearing carriage were estimated. RESULTS: The posterior mean of within-room transmission rate was 1.05 per month (Portugal) vs. 0.63 per month (Finland). The smaller rate of clearance in Portugal (0.57 vs. 0.73 per month) is in accordance with the children being younger. The overall community rate of acquisition was larger in the Portuguese setting (0.25 vs. 0.11 per month), in agreement with that the groups belonged to a larger DCC. The model adequately predicted the observed levels of carriage prevalence and longitudinal patterns in carriage acquisition and clearance. CONCLUSIONS: The difference in prevalence of carriage (61% in Portuguese vs. 26% among Finnish DCC attendees) was assigned to the longer duration of carriage in younger attendees and a significantly higher rate of within-room transmission and community acquisition in the Portuguese setting.

Pneumococcemia in children--a retrospective study before universal pneumococcal vaccinations.

AIM: To evaluate the incidence and characteristics of blood culture-positive occult pneumococcemia compared with blood culture-positive pneumococcal pneumonia in children. METHODS: In years 2001-2010, 105 children with positive blood cultures for Streptococcus pneumoniae were identified from hospital electronic files. The patient cards were retrospectively charted for clinical and laboratory data, and 38 patients had and 67 had not pneumonia. RESULTS: The annual incidence of pneumococcemia was, on average, 29.0/10 000 at 0-12 months, 5.3/10 000 at 13-24 months and 1.9/10 000 at 2-4 years of ages, with no increasing or decreasing trend. The incidence of bacteraemic pneumococcal pneumonia increased (p = 0.022) during the study period. The duration of fever before hospitalization (<24 h 73.9% vs. 25.0%, p = 0.022) and the duration of intravenous antibiotics, usually G-penicillin (median 72 vs. 96 h, p = 0.021) was shorter in pneumococcemia patients. On admission, blood leucocyte count was higher in pneumococcemia (mean 26.6 vs. 21.9 × 10E9/L, p = 0.012), but serum CRP was higher in pneumonia (median 160 vs. 67.4 mg/L, p < 0.001). The serotypes 6B and 14 caused 53.2% of pneumococcemia cases. CONCLUSION: The incidence of pneumococcemia was highest in 1-2-year-old children, and typical for pneumococcemia was rapid onset of fever, high blood leucocyte count and a modestly elevated CRP on admission.

Adenoidectomy in young children and serum IgG antibodies to pneumococcal surface protein A and choline binding protein A.

OBJECTIVE: We have previously reported that surgical removal of the nasopharyngeal adenoid in young children resulted in increased risk of nasopharyngeal colonization by pneumococci. We now investigated whether adenoidectomy influences the development of serum IgG antibodies to pneumococcal choline-binding protein A (CbpA) and pneumococcal surface protein A (PspA). METHODS: Altogether 217 children aged 12-48 months who had recurrent or persistent otitis media were randomized to undergo or not to undergo adenoidectomy. All the children underwent insertion of tympanostomy tubes. 166 children were followed-up for 3 years. The main outcome measures were concentrations of serum IgG antibodies to CbpA and PspA three years after randomization. Nasopharyngeal colonization by pneumococci was assessed 1, 2, and 3 years after randomization. RESULTS: Adenoidectomy decreased concentrations of CbpA antibodies by ca. 25% independently of the observed increase in pneumococcal carriage (OR of log(10) transformed concentrations 0.74, 95% CI 0.58-0.94, P=0.016). Concentrations of PspA antibodies were lower and they seemed not to be influenced by adenoidectomy. CONCLUSIONS: Adenoidectomy in young children causes a small but detectable impairment in the development of serum IgG antibodies to pneumococcal CbpA. The adenoid seems to have a role in augmenting systemic immunity against pneumococci.

From Quellung to multiplex PCR, and back when needed, in pneumococcal serotyping.

All currently available vaccines against Streptococcus pneumoniae are based on selections of the over 90 different serotypes, which underlines the importance of serotyping for surveillance and vaccine efficacy monitoring. In this study, we modified and validated a PCR-based scheme for deducing the serotypes of the invasive pneumococci isolated in Finland. For validation, 170 isolates were serotyped using the new protocol with six sequential multiplex PCRs for the deduction of serotypes, supplemented with Quellung testing when needed. The results were compared with those obtained by traditional serotyping methods. We found that 98.8% (168/170) of the isolates were correctly serotyped by the new protocol. Subsequently, the scheme was taken into regular use for serotyping the invasive pneumococci isolated in Finland for serotype-specific surveillance purposes and has been applied in the serotyping of more than 1,500 invasive isolates so far. The sequential multiplex PCRs (mPCRs) have given a result for over 99% of the isolates and allowed us to both handle samples in bulk and noticeably reduce the cost of reagents. While serotyping primarily by PCR is precise and effective, Quellung testing remains the most reliable way to discover possible discrepancies between the DNA deduced and the phenotypic serotype of an isolate. Since implementing the protocol for regular use, two serotype 19F PCR-positive isolates were found to be serotype 19A by the Quellung reaction. While a rare occurrence, this is an important observation, which prompted a revision of our serotyping protocol to prevent possible underreporting of serotype 19A, a potential replacement serotype following large-scale vaccination.

Comparison of the severity and outcome of invasive pneumococcal infections in children and adults.

In a population-based observational study of 285 patients with positive blood culture for pneumococci, we found that the course and outcome of invasive pneumococcal infections differ considerably between adults and children. None of the children died, whereas the infection was fatal for 15% (35/229) of the adults (P<0.001). The differences are only partly explained by the underlying conditions.

Nasopharyngeal carriage of Streptococcus pneumoniae and pneumococcal urine antigen test in healthy elderly subjects.

BACKGROUND: Children frequently carry Streptococcus pneumoniae (pneumococcus) in their nasopharynx, even when healthy. Lower carriage rates have been reported in adults and only sparse data are available for the elderly. We sampled healthy elderly subjects for nasopharyngeal carriage to assess the prevalence of pneumococcal carriage using various assays. METHODS: A deep nasopharyngeal swab sample was taken from 590 healthy elderly subjects aged ≥ 65 y. The samples were stored in STGG (skim milk-tryptone-glucose-glycerol) medium and cultured directly and after incubation in enrichment broth using routine identification methods. Real-time polymerase chain reaction (PCR) assays specific for pneumolysin and pneumococcal surface antigen A genes was performed on the same samples. Urine was also collected and assayed using the commercial Binax Streptococcus pneumoniae NOW urine antigen test. RESULTS: The prevalence of pneumococcal carriage in healthy elderly persons was 1.5% for encapsulated pneumococci and 5.3% for all presumptive pneumococci. The use of the enrichment broth did not increase the yield of positives. PCR assays gave higher numbers of positives, but pneumolysin PCR in particular gave probable false-positive results. Only 1 urine antigen test was positive, and this was in a person not carrying pneumococcus. CONCLUSIONS: Nasopharyngeal carriage of pneumococci in the elderly was rare. Identification of presumptive pneumococci in culture requires further confirmation, e.g. by serotyping. The urine antigen test was not affected by concurrent carriage. Low carriage prevalence suggests that encapsulated pneumococci detected in a respiratory tract sample during sickness may be the true cause of disease, since contamination from asymptomatic nasopharyngeal carriage seems unlikely.

Effect of xylitol and other carbon sources on Streptococcus pneumoniae biofilm formation and gene expression in vitro.

Xylitol inhibits the growth of Streptococcus pneumoniae. In clinical trials, xylitol decreased the occurrence of acute otitis media in day-care children, but did not decrease nasopharyngeal carriage of pneumococci. We hypothesized that xylitol inhibits biofilm formation of pneumococci, and measured biofilm formation and gene expression levels of the capsule gene cpsB and two other genes: autolysin encoding gene lytA and competence gene comA in different growth media in vitro. Twenty pneumococcal isolates were grown on polystyrene plates for 18 h in test media containing 0.5% xylitol, 0.5% glucose, 0.5% xylitol and 0.5% glucose, 0.5% fructose, 0.5% xylitol and 0.5% fructose or brain heart infusion (BHI) medium supplemented with 10% horse serum. Gene expression levels were measured after 5 h of growth using a relative quantification method with calibrator normalization. Exposure to xylitol lowered OD values, which were used as an indication of biofilm, compared with BHI medium, but when the medium was supplemented with glucose or fructose, biofilm formation was enhanced and the inhibitory effect of xylitol on biofilm formation was not observed. Xylitol also lowered lytA expression levels. Changes in biofilm formation in response to different sugar compounds may partly explain the efficacy of xylitol to prevent acute otitis media in previous clinical trials.

Pneumococcal carriage is more common in asthmatic than in non-asthmatic young men.

INTRODUCTION: The aim was to investigate the prevalence of oropharyngeal carriage of Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Neisseria meningitidis and beta-haemolytic streptococci among asthmatic and non-asthmatic young Finnish men and to identify putative risk factors. OBJECTIVES: A total of 224 asthmatics and 668 non-asthmatic men (mean age 19.6 years) from two intakes of conscripts to the Kainuu Brigade, Finland in July 2004 and January 2005 were enrolled upon entering military service. METHODS: Oropharyngeal specimens were examined for bacteria by routine culture methods. All the participants filled in questionnaires concerning risk factors for asthma and respiratory infections. RESULTS: S. pneumoniae (48 cases, 5.4%), Group A streptococci (16, 1.8%), H. influenzae (45, 5.0%), M. catarrhalis (24, 2.7%) and N. meningitidis (20, 2.2%) were isolated from the 892 participants. Ten putative risk factors for oropharyngeal colonization (asthma, atopy, allergic rhinitis, smoking, current use of asthma medication, history of adeno/tonsillectomy, level of highly sensitive C-reactive protein, peak expiratory flow, results of a 12-min running test and body mass index) were evaluated. The only significant risk factor for S. pneumoniae carriage was asthma (OR, 2.04; 95% CI 1.12 to 3.72). CONCLUSIONS: Pneumococcal carriage is more common in asthmatic than in non-asthmatic young men.

Serotype-related variation in susceptibility to complement deposition and opsonophagocytosis among clinical isolates of Streptococcus pneumoniae.

The polysaccharide capsule is a major virulence factor of Streptococcus pneumoniae; it affects complement resistance and shields the bacterium from phagocytes. Certain capsular serotypes appear to be better able to cause invasive disease than others. Serotypes 1 and 5 are common causes of invasive disease but are rarely isolated from healthy carriers, whereas serotypes 6B and 23F are more frequently isolated from carriage than invasive disease. We have recently shown that serotypes 6B and 19F differ in resistance to complement C3 deposition and opsonophagocytic killing. In this study we assessed the complement resistance and susceptibility to opsonophagocytosis of several other serotypes targeted by the pneumococcal conjugate vaccines. Clinical isolates of serotypes 1, 4, 5, 14, 18C, and 23F were tested along reference strains of corresponding capsular types. The concentration of anticapsular antibodies required for opsonophagocytic killing correlated inversely with C3 deposition on the serotype. Serotype 1 was the most resistant of the clinical isolates to C3 deposition and, along with serotypes 5 and 19F, required the highest concentration of capsule antibodies for opsonophagocytic killing, whereas serotype 23F was the most sensitive to opsonophagocytosis. Sensitivity to C3 deposition and opsonophagocytosis was associated with serotype-specific mortality of invasive pneumococcal disease, suggesting that the primary pathogens, such as serotypes 1 and 5, are more resistant to complement and require a higher concentration of capsule antibodies for opsonophagocytic killing than the opportunistic serotypes such as 6B and 23F, which are associated with a more severe disease outcome.

Risk of invasive pneumococcal infections among working age adults with asthma.

BACKGROUND: Information about the risk of invasive pneumococcal infection (IPI) among adults with asthma is limited and inconsistent. To evaluate this association, a population-based case-control study was conducted. METHODS: Cases of IPI (Streptococcus pneumoniae isolated from blood or cerebrospinal fluid) were identified through national, population-based laboratory surveillance during 1995-2002. To maximise exclusion of chronic obstructive pulmonary disease, the analysis was limited to patients aged 18-49 years and 10 selected age-, sex- and health district-matched controls for each case from the Population Information System. Information on underlying medical conditions was obtained through linking surveillance data to other national health registries. Asthma requiring > or =1 hospitalisation in the past 12 months was defined as high risk asthma (HRA); low risk asthma (LRA) was defined as entitlement to prescription drug benefits and no hospitalisation for asthma in the past 12 months. RESULTS: 1282 patients with IPI and 12 785 control subjects were identified. Overall, 7.1% of cases and 2.5% of controls had asthma (6.0% and 2.4% had LRA whereas 1.1% and 0.1% had HRA, respectively. After adjustment for other independent risk factors in a conditional logistic regression model, IPI was associated with both LRA (matched OR (mOR) 2.8; 95% CI 2.1 to 3.6) and HRA (mOR, 12.3; 95% CI 5.4 to 28.0). The adjusted population-attributable risk was 0.039 (95% CI 0.023 to 0.055) for LRA and 0.01 (95% CI 0.0035 to 0.017) for HRA. CONCLUSIONS: Working age adults with asthma are at increased risk of IPI. In this population, approximately 5% of disease burden could be attributed to asthma. These findings support adding medicated asthma in adults to the list of indications for pneumococcal vaccination.

Presence of capsular locus genes in immunochemically identified encapsulated and unencapsulated Streptococcus pneumoniae sputum isolates obtained from elderly patients with acute lower respiratory tract infection.

The principal virulence factor of Streptococcus pneumoniae is capsular polysaccharide, and encapsulated pneumococci are more common causes of disease than unencapsulated strains. This study analysed the presence of capsular genes in 59 pneumococcal isolates using two PCR methods targeted at the cpsA and cpsB genes of the capsular biosynthesis locus. The PCR method targeted at the cpsB gene, reported to be essential for encapsulation, was developed in this study. Of 59 pneumococcal isolates, 49 (83 %) were obtained from the sputum samples of elderly patients (≥65 years) with community-acquired pneumonia (CAP) and 10 (17 %) were from those with other acute lower respiratory tract infections (ARIs). Forty (82 %) of the CAP isolates and two (20 %) of the ARI isolates were encapsulated, as assessed by conventional immunochemical methods. Forty-one (98 %) of the 42 encapsulated strains had the cpsB gene present, and in 38 strains the cpsA gene was also detected. One of the unencapsulated isolates gave a positive result for the cpsB gene, and neither of the capsular locus genes were present in all the other unencapsulated strains. The distribution of encapsulated and unencapsulated isolates differed significantly between the two patient groups regardless of whether the presence of capsule was determined immunochemically (P<0.001) or by cpsB PCR (P=0.002). The cpsB PCR developed here was found to be a rapid and reliable method to detect the pneumococcal capsule locus and may have potential in sputum diagnostics when investigating the pneumococcal aetiology of CAP.

Adenoidectomy and nasopharyngeal carriage of Streptococcus pneumoniae in young children.

OBJECTIVE: The effect of adenoidectomy on nasopharyngeal colonisation of pathogens has not previously been evaluated. The authors studied the effect of adenoidectomy on nasopharyngeal colonisation by bacteria causing otitis media and the effect of adenoidectomy on the development of pneumococcal capsular polysaccharide antibodies. DESIGN: Randomised controlled study. SETTING: Tertiary care centre. PATIENTS: 217 children aged 12-48 months who had recurrent or persistent otitis media were randomised. 166 children were followed up for 3 years. INTERVENTION: Random allocation to undergo adenoidectomy or not to undergo adenoidectomy. All the children underwent insertion of tympanostomy tubes. MAIN OUTCOME MEASURES: Nasopharyngeal colonisation by pneumococci, Haemophilus influenzae and Moraxella catarrhalis 1, 2 and 3 years after randomisation. Serum IgG antibodies against pneumococcal capsular polysaccharide serotypes 6B, 14, 19F and 23F 3 years after randomisation. RESULTS: After the first year of randomisation adenoidectomy increased nasopharyngeal carriage of pneumococci (RR, 1.47; 95% CI 1.04 to 2.07) but it did not influence the carriage of H influenzae or M catarrhalis. Among carriers of serotype 6B pneumococci, adenoidectomy resulted in lower concentrations of pneumococcal serotype 6B polysaccharide antibodies (ratio of geometric means of antibody concentrations, 0.37; 95% CI 0.16 to 0.85). Concentrations of serotype 14, 19F and 23F antibodies seemed not to be influenced by adenoidectomy. Despite this, adenoidectomy resulted in a significant increase in nasopharyngeal carriage of serotype 19F pneumococci. CONCLUSIONS: Adenoidectomy increases the risk of nasopharyngeal carriage of pneumococci in children younger than 4 years of age. This may be independent of the development of serum IgG capsular polysaccharide antibodies.

Biofilm formation by Streptococcus pneumoniae isolates from paediatric patients.

The clinical significance of pneumococcal biofilm formation is largely unknown. To clarify this, we tested whether the ability of pneumococcal clinical isolates to form biofilm in vitro accounts for the diverse clinical outcomes. Clinical pneumococcal isolates were cultured from the nasopharynx (n=106), middle ear effusion (n=43) and blood (n=55) of 204 children altogether. Biofilm formation, assessed by measuring optical density (OD) values in microtitre plates after crystal violet staining, did not differ between the bacteria from different sources (p=0.18), the mean OD values of the isolates being 0.119 [95% confidence interval (CI) 0.100-0.138] in the nasopharynx samples, 0.094 (95% CI 0.069-0.119) in the acute otitis media cases, 0.109 (95% CI 0.077-0.141) in the secretory otitis media cases, 0.122 (95% CI 0.084-0.160) in those with sepsis and 0.175 (95% CI 0.071-0.280) in those with other invasive infections. Serotypes 33 and 14 were the most efficient in forming biofilms, whereas serotypes 3 and 38 were poor biofilm producers. We conclude that the clinical presentation of pneumococcal disease did not differ in relation to biofilm formation in vitro, even though there was marked variation between the clinical isolates and serotypes.