[Apexxnar®, 20-valent pneumococcal conjugate vaccine]

Streptococcus pneumoniae infections cause bacteremic and non-bacteremic community-acquired pneumonia and invasive pneumococcal diseases (IPD) such as bacteremia, sepsis and acute meningitis. They are potentially lethal. Although polysaccharide vaccines (PPV23, Pneumovax 23®) have already provided protection in at-risk individuals, they have been imperfect, mainly because the development of anti-polysaccharide antibodies occurs without the help of T cells. The introduction of immunogenic protein conjugate vaccines (ICVs) has overcome this problem and provided better and longer lasting protection. The first available vaccine of this type for adults was Prevenar 13®, targeting 13 polysaccharides of S. pneumoniae (PCV13). A new vaccine, Apexxnar®, targeting 20 polysaccharides (PCV20), the 13 of Prevenar 13®, to which 7 other serotypes considered to be equally responsible for invasive infections have been added, has recently been launched. Clinical studies have demonstrated a good immunogenic response against all 20 serotypes in adult patients who are either vaccine-naive or previously vaccinated with PPV23 and/or PCV13. Furthermore, the tolerance of the PCV20 vaccine was found to be comparable to that of Prevenar 13®. Vaccination with PCV20 involves a single injection. The Belgian Superior Health Council has recently reiterated the importance of vaccinating at-risk individuals against S. pneumoniae (a vaccination that is still under-performed). It now recommends vaccination with PCV20 (Apexxnar®) as the preferred primary vaccination regimen in high-risk adults with co-morbidities or in good health aged between 65 and 85 years.

Emergence of Streptococcus pneumoniae serotype 19A (Spn19A) in the pediatric population in Bogotá, Colombia as the main cause of invasive pneumococcal disease after the introduction of PCV10

Introduction: With the use of pneumococcal conjugate vaccines(PCV), the behavior of invasive pneumococcal disease(IPD) has changed relative to serotype distribution. The introduction of these vaccines in national immunization programs has reduced the incidence of IPD, with a marked decrease in the circulation of the serotypes included in the vaccine used in each country. However, the subsequent emergence of other serotypes not included in the vaccine, such 19A in case of PCV7 and PCV10, has been documented. Materials and methods: This was case series study (2008-2017) in pediatric patients admitted to 10 hospitals in Bogota who were diagnosed with IPD. It was conducted during the transitional period of implementing the PCV10 vaccine in Colombia in 2012. Cases of bacteremic pneumococcal pneumonia, meningitis, primary bacteremia and osteoarticular infection were included. A descriptive analysis of the demographic, clinical and laboratory variables of patients with IPD by Spn19A, its trend over time, profiles of antimicrobial susceptibility and clinical outcomes was performed. Results: There were 463 cases of IPD, 315(68%) with known serotypes. The prevalence of IPD by Spn19A was 17.7%(56 cases), tending to increase over time. During 2008-2011, the prevalence was 4.4%, and during 2014-2017, it was 32.4%, The most frequent diagnosis was pneumonia(80.4%). In nonmeningeal isolates, 39.6% were not susceptible to penicillin. An increase in the resistance was observed over time. Conclusion: Spn19A is a prevalent cause of IPD in the pediatric population of the analyzed cohort, with an increasing trend of this serotype during the surveillance period after the introduction of PCV10, being the most common serotype identified in recent years.

Impact of pneumococcal conjugate vaccine on the carriage density of Streptococcus pneumoniae and Staphylococcus aureus in children living with HIV: a nested case-control study

Nasopharyngeal colonization density of Streptococcus pneumoniae (pneumococcus) is associated with disease severity and transmission. Little is known about the density of pneumococcal carriage in children with HIV (CLH). Pneumococcal vaccines may impact the density of pneumococcus and competing microbes within the nasopharynx. We examined the impact of one dose of PCV13 on carriage density of pneumococcus and Staphylococcus aureus, in CLH, HIV-uninfected children (HUC), and their unvaccinated parents. We conducted a pilot-nested case-control study, within a larger prospective cohort study, on the impact of PCV13, in families in West Bengal India. Quantitative real-time PCR was run on 147 nasopharyngeal swabs from 27 CLH and 23 HUC, and their parents, before and after PCV13 immunization. CLH had higher median pneumococcal carriage density, compared to HUC: 6.28 × 108 copies/mL vs. 2.11 × 105 copies/mL (p = .005). Following one dose of PCV13, pneumococcal densities dropped in both groups, with an increase in S. aureus carriage to 80% from 48% in CLH, and to 60% in HUC from 25%. While limited in sample size, this pilot study shows that CLH carried higher densities of pneumococcus. PCV13 was associated with a decrease in pneumococcal density and a temporal increase in S. aureus carriage regardless of HIV status.

Influenza virus infection complicated by bacterial necrotising pneumonia: two case reports

Necrotising pneumonia (NP) is a potentially severe complication of community-acquired pneumonia characterised by necrosis of consolidated lung tissue. A 7-year-old boy and a 6-year-old boy are presented, both of whom had a complicated influenza infection which evolved into severe NP caused by Streptococcus pneumoniae. Both needed intensive care for invasive respiratory support. Despite extensive pleural involvement in both cases, only one required thoracic surgery. Case 1 also developed anaemia, hyponatraemia and hypo-albuminaemia, resulting in generalised oedema. Despite the severe morbidity, both boys made a full recovery. The diagnosis of NP should always be considered in a child with pneumonia who remains unwell despite 72 hours of appropriate antibiotics, particularly if there is evidence of pleural disease. Although S. pneumoniae is the main agent for NP, the influenza virus may be a precipitating factor.

Co-colonization by Streptococcus pneumoniae and Staphylococcus aureus in the throat during acute respiratory illnesses

Pneumonia due to either Streptococcus pneumoniae (Sp) or Staphylococcus aureus (Sa) accounts for most mortality after influenza and acute respiratory illness (ARI). Because carriage precedes infection, we estimated Sp and Sa carriage to examine the co-colonization dynamics between Sp, Sa and respiratory viruses in the presence of ARI in the oropharynx. We tested oropharyngeal specimens of community subjects (aged ⩾2 years) with ARI for the presence of influenza A and B, 11 other common respiratory viruses, Sp and Sa, using real-time PCR. A total of 338 participants reported 519 ARI episodes of which 119 (35%) carried Sp, 52 (13%) carried Sa and 25 (7%) carried both. Thirty-five subjects tested positive for influenza, of which 14 (40%) carried Sp and six (17%) carried Sa, significantly more than in the influenza-negative group (P = 0·03 and P = 0·04, respectively). In subjects infected by any virus compared to those with no virus, Sp carriage (39·2% vs. 27·9%, P = 0·03) but not Sa carriage (11·6% vs. 14%, P = 0·6) was more frequent. For children, when Sa was present, Sp carriage tended to be less frequent than expected given the presence of viral infection, but not significantly [observed relative risk 1·14, 95% confidence interval (CI) 0·4-3·1; with a relative excess risk due to interaction of -0·11]. Independent of age, Sp carriers were more likely to return that season with subsequent ARI (odds ratio 2·14, 95% CI 1·1-4·3, P = 0·03). Both Sp and Sa carriage rates in the oropharynx increase during influenza infection in children. However, no negative interaction between Sp and Sa was observed. Sp carriers are more likely to suffer subsequent ARI episodes than non-carriers.