Trends in laboratory-confirmed bacterial meningitis (2012-2019): national observational study, England

Background

Bacterial meningitis is associated with significant morbidity and mortality worldwide. We aimed to describe the epidemiology, aetiology, trends over time and outcomes of laboratory-confirmed bacterial meningitis in England during 2012-2019.

Methods

UK Health Security Agency routinely receives electronic notifications of confirmed infections from National Health Service hospital laboratories in England. Data were extracted for positive bacterial cultures, PCR-positive results for Neisseria meningitidis or Streptococcus pneumoniae from cerebrospinal fluid and positive blood cultures in patients with clinical meningitis.

Findings

During 2012-19, there were 6554 laboratory-confirmed cases. Mean annual incidence was 1.49/100,000, which remained stable throughout the surveillance period (p = 0.745). There were 155 different bacterial species identified, including 68.4% (106/1550) Gram-negative and 31.6% (49/155) Gram-positive bacteria. After excluding coagulase-negative staphylococci (2481/6554, 37.9%), the main pathogens causing meningitis were Streptococcus pneumoniae (811/4073, 19.9%), Neisseria meningitidis (497/4073, 12.2%), Staphylococcus aureus (467/4073, 11.5%), Escherichia coli (314/4073, 7.7%) and group B streptococcus (268/4073, 6.6%). Pneumococcal meningitis incidence increased significantly during 2012-9, while meningococcal, group A streptococcal and tuberculous meningitis declined. Infants aged <3 months had the highest mean incidence (55.6/100,000; 95% CI, 47.7-63.5) driven mainly by group B streptococci, followed by 3-11 month-olds (8.1/100,000; 95% CI 7.1-9.0), where pneumococcal and meningitis predominated. The 30-day case-fatality rate (CFR) was 10.0% (71/6554). Group A streptococcal meningitis had the highest CFR (47/85, 55.3%). The probability of surviving at 30 days was 95.3% (95% CI, 93.4-97.3%) for infants and 80.0% for older adults (77-84%).

Interpretation

The incidence of bacterial meningitis has remained stable. The high CFR highlights a need for prevention through vaccination.

Funding

PHE.

Preclinical in vitro and in vivo profile of a highly-attenuated, broadly efficacious pneumolysin genetic toxoid

Pneumolysin is a highly conserved, cholesterol-dependent cytolysin that is an important Streptococcus pneumoniae virulence factor and an attractive target for vaccine development. To attenuate pneumolysin toxicity, a genetic toxoid was constructed with two amino acid changes, G293S and L460D, termed PLY-D, that reduced cytolytic activity > 125,000-fold. In mice, PLY-D elicited high anti-PLY IgG antibody titers that neutralized the cytolytic activity of the wild-type toxin in vitro. To evaluate the protective efficacy of PLY-D, mice were immunized intramuscularly and then challenged intranasally with a lethal dose of 28 clinical isolates of S. pneumoniae originating from different geographical locations, disease states (i.e. bacteremia, pneumonia), or body sites (i.e. sputum, blood). PLY-D immunization conferred significant protection from challenge with 17 of 20 serotypes (85%) and 22 of 28 strains (79%). Further, we demonstrated that immunization with PLY-D provided statistically significant improvement in survival against challenge with serotype 4 and 18C strains compared to mice immunized with a pneumococcal conjugate vaccine Prevnar 13® (PCV13). Co-administration of PLY-D and PCV13 conferred greater protection against challenge with a serotype 6B strain than immunization with either vaccine alone. These data indicate that PLY-D is a broadly protective antigen with the potential to serve as a serotype-independent vaccine against invasive pneumococcal disease either alone or in combination with PCVs.

Characteristics and Serotype Distribution of Childhood Cases of Invasive Pneumococcal Disease Following Pneumococcal Conjugate Vaccination in England and Wales, 2006-2014

Background

The 7-valent and 13-valent pneumococcal conjugate vaccines (PCV7 and PCV13, respectively) are highly effective in preventing invasive pneumococcal disease (IPD) caused by vaccine serotypes. Vaccine failure (vaccine-type IPD after age-appropriate immunization) is rare. Little is known about the risk, clinical characteristics, or outcomes of PCV13 compared to PCV7 vaccine failure.

Methods

Public Health England conducts IPD surveillance and provides a national reference service for serotyping pneumococcal isolates in England and Wales. We compared the epidemiology, rates, risk factors, serotype distribution, clinical characteristics, and outcomes of IPD in children with PCV13 and PCV7 vaccine failure.

Results

A total of 163 episodes of PCV failure were confirmed in 161 children over 8 years (4 September 2006 to 3 September 2014) in 10 birth cohorts. After 3 vaccine doses, PCV7 and PCV13 failure rates were 0.19/100000 (95% confidence interval [CI], .10-.33 [57 cases]) and 0.66/100000 (95% CI, .44-.95 [104 cases]) vaccinated person-years, respectively. Children with PCV13 failure were more likely to be healthy (87/105 [82.9%] vs 37/56 [66.1%]; P = .02), present with bacteremic lower respiratory tract infection (LRTI) (61/105 [58.1%] vs 11/56 [19.6%]; P < .001), and develop empyema (41/61 [67.2%] vs 1/11 [9.1%]; P < .001) compared to PCV7 failures. Serotypes 3 (n = 38 [36.2%]) and 19A (n = 30 [28.6%]) were responsible for most PCV13 failures. Six children died (4% [95% CI, 1%-8%]), including 5 with comorbidities.

Conclusions

PCV failure is rare and, compared to PCV7 serotypes, the additional PCV13 serotypes are more likely to cause bacteremic LRTI and empyema in healthy vaccinated children.

Risk of Invasive Pneumococcal Disease in Children with Sickle Cell Disease in England: A National Observational Cohort Study, 2010-2015

OBJECTIVE

To describe the clinical presentation, risk factors, serotype distribution and outcomes of invasive pneumococcal disease (IPD) in children with sickle cell disease (SCD) following the introduction of the 13-valent pneumococcal conjugate vaccine (PCV13) in the UK.

DESIGN

Prospective national newborn screening for SCD and enhanced national IPD surveillance.

PARTICIPANTS

Children with SCD born in England between 1 September 2010 and 31 August 2014 who developed laboratory-confirmed IPD by 31 December 2015.

MAIN OUTCOMES AND MEASURES

Risk of IPD in children with SCD compared with children without SCD during the surveillance period.

RESULTS

Eleven children homozygote for haemoglobin S (HbSS) and one double heterozygote for haemoglobin S and C (HbSC) developed IPD. Septicaemia (n=7) and lower respiratory tract infection (n=4) were the main clinical presentations, and serogroup 15 (not present in PCV13) was responsible for 73% (8/11) of cases. Three children with HbSS (27%) died compared with <5% nationally. Children with HbSS had a 49-fold (95% CI 27 to 89, P<0.001) higher risk of IPD compared with their peers without SCD.

CONCLUSIONS

Children with SCD remain at increased risk of IPD despite national newborn screening, early penicillin prophylaxis and high pneumococcal vaccine uptake. They are also more likely to die of their infection compared with their peers without SCD. Most IPD cases are now due to serotypes not covered by PCV13. Healthcare professionals need to work more closely with families with SCD and local communities to emphasise the importance of penicillin prophylaxis, explore barriers, allay misguided beliefs and facilitate rapid access to healthcare.

Changes in the Nature and Severity of Invasive Pneumococcal Disease in Children Before and After the Seven-valent and Thirteen-valent Pneumococcal Conjugate Vaccine Programs in Calgary, Canada

BACKGROUND

Since the introduction of childhood pneumococcal conjugate vaccines, invasive pneumococcal disease (IPD) incidence has decreased in children and the predominant serotypes causing disease have changed. This study describes changes in the clinical features of IPD in children (<18 years) before and after the conjugate vaccine introduction.

METHODS

The Calgary Area Streptococcus pneumoniae Epidemiology Research study collects information on all IPD cases in Calgary, Alberta, Canada. Descriptive and regression analyses were used to compare IPD in the pre-vaccine (January 2000 to August 2002), post-7-valent protein-polysaccharide conjugate vaccine (September 2002 to June 2010) and post-13-valent protein-polysaccharide conjugate vaccine (PCV13) (July 2010 to December 2015) periods; intensive care unit and inpatient admissions were outcome measures.

RESULTS

The incidence of IPD in children (<18 years) decreased from an average of 17 cases/100,000/yr in 2000-2001 to 4 cases/100,000/yr in 2015. The median age of children presenting with IPD shifted from 2.0 years (interquartile range: 2.5) in the pre-vaccine period to 3.9 years (interquartile range: 6.2) in the post-PCV13 period. The proportion of children with a comorbidity that is an indication for pneumococcal vaccination did not change. Invasive disease with focus (meningitis, pneumonia, empyema, peritonitis) compared with invasive disease with bacteremia only increased from 44.6% in pre-vaccine to 64.0% and 61.4% in the post-7-valent protein-polysaccharide conjugate vaccine and post-PCV13 periods, respectively (P = 0.017). Having IPD in the post-PCV13 period compared with the pre-vaccine period was associated with an increased odds of hospitalization [Odds ratio (OR): 2.9; 95% Confidence Interval (CI): 1.4-6.2].

CONCLUSIONS

Clinical features of IPD have changed since pneumococcal conjugate vaccines were introduced, with a shift toward more focal infections requiring hospitalization. Although overall IPD cases have declined, disease that does occur appears to be more severe.

From Immunologically Archaic to Neoteric Glycovaccines

Polysaccharides (PS) are present in the outermost surface of bacteria and readily come in contact with immune cells. They interact with specific antibodies, which in turn confer protection from infections. Vaccines with PS from pneumococci, meningococci, Haemophilus influenzae type b, and Salmonella typhi may be protective, although with the important constraint of failing to generate permanent immunological memory. This limitation has in part been circumvented by conjugating glycovaccines to proteins that stimulate T helper cells and facilitate the establishment of immunological memory. Currently, protection evoked by conjugated PS vaccines lasts for a few years. The same approach failed with PS from staphylococci, Streptococcus agalactiae, and Klebsiella. All those germs cause severe infections in humans and often develop resistance to antibiotic therapy. Thereby, prevention is of increasing importance to better control outbreaks. As only 23 of more than 90 pneumococcal serotypes and 4 of 13 clinically relevant Neisseria meningitidis serogroups are covered by available vaccines there is still tremendous clinical need for PS vaccines. This review focuses on glycovaccines and the immunological mechanisms for their success or failure. We discuss recent advances that may facilitate generation of high affinity anti-PS antibodies and confer specific immunity and long-lasting protection.