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Ongoing surveillance after pneumococcal conjugate vaccination (PCV) deployment is essential to inform policy decisions and monitor serotype replacement. We report serotype and disease severity trends in 3,719 adults hospitalized for pneumococcal disease in Bristol and Bath, United Kingdom, during 2006–2022. Of those cases, 1,686 were invasive pneumococcal disease (IPD); 1,501 (89.0%) had a known serotype. IPD decreased during the early COVID-19 pandemic but during 2022 gradually returned to prepandemic levels. Disease severity changed throughout this period: CURB65 severity scores and inpatient deaths decreased and ICU admissions increased. PCV7 and PCV13 serotype IPD decreased from 2006–2009 to 2021–2022. However, residual PCV13 serotype IPD remained, representing 21.7% of 2021–2022 cases, indicating that major adult PCV serotype disease still occurs despite 17 years of pediatric PCV use. Percentages of serotype 3 and 8 IPD increased, and 19F and 19A reemerged. In 2020–2022, a total of 68.2% IPD cases were potentially covered by PCV20.

Abstract Background The thirteen-valent pneumococcal conjugate vaccine (PCV13) is not included in the national immunization program and is administered voluntarily with informed consent in China. In preparation for assessing the impact of pilot introduction in Hainan Province, we conducted a carriage study among children under 5 years of age from four locations in Hainan Province, China. Methods From March to June 2022, nasopharyngeal (NP) swabs, collected from healthy children aged younger than 59 months who lived in the 4 different locations (Haikou, Wanning, Baisha and Qiongzhong) in Hainan Province, were tested for pneumococcus using conventional culture. Pneumococcal isolates were serotyped using the Quellung reaction. Risk factors associated with pneumococcal colonization were assessed using univariate analysis and multivariable logistic regression adjusting for age, daycare attendance and other factors. Results Pneumococcus was isolated in 710 (30.4%) of the 2333 children enrolled. Of 737 pneumococci, 29 serotypes were identified; 60.9% were PCV13 serotypes; the most common vaccine serotypes were 6B (20.4%), 19F (13.0%), 6A (11.9%) and 23F (6.1%); and the most common nonvaccine serotypes were 23A (12.9%), 34 (6.1%) and nontypeable (NT) pneumococci (5.6%). Children vaccinated with PCV13 had lower carriage (17.7% vs 32.5%; P = 0.0001) and fewer PCV13 serotypes (41.9% vs 62.7%; P = 0.0017) compared to unimmunized children. After adjustment, NP carriage was higher among children attending daycare (aOR = 2.3, 95% CI: 1.7–3.2), living in rural areas (aOR = 1.4, 95% CI: 1.1–1.8), living with siblings (aOR = 1.3, 95% CI: 1.0–1.6) and whose mothers had completed senior high/technical secondary school (aOR = 1.5, 95% CI: 1.1–2.0). In contrast, completion of 3–4 doses of PCV13 were associated with a lower carriage rate (aOR = 0.6, 95% CI: 0.4–0.9). Conclusions We established the baseline of pneumococcal carriage, serotype distribution and PCV13 immunization rates among healthy children under 5 years of age in Hainan Province, prior to the introduction of PCV13 into the national immunization program. The high proportion of PCV13 serotypes suggests that PCV13 introduction will likely have a substantial impact on pneumococcal carriage in Hainan Province. Graphical Abstract

•IPD serotype distribution in older adults from high-income countries was described.•Serotypes 3 and 19A were common in countries with pediatric PCV10 and PCV13 use.•PCV20 provides the highest IPD serotype coverage among older adults.•Vaccination of older adults with higher-valency PCVs could reduce the IPD burden. Neither indirect protection through use of 13-valent and 10-valent pneumococcal conjugate vaccines (PCV13 and PCV10) in pediatric National Immunization Programs (NIPs) nor direct vaccination with the 23-valent polysaccharide vaccine have eliminated vaccine serotype invasive pneumococcal disease (IPD) in older adults. Vaccinating older adults with higher-valency PCV15 and PCV20 could address remaining IPD due to pediatric PCV serotypes plus additional IPD due to serotypes included in these vaccines. We collected serotype-specific IPD data in older adults (≥65 years in most countries), from national or regional surveillance systems or hospital networks of 33 high-income countries. Data were from official government websites, online databases, surveillance system reports, published literature, and personal communication with in-country investigators. Average percentages of IPD serotypes were calculated. Among 52,905 cases of IPD with a serotype identified, PCV13 serotypes accounted for 33.7% of IPD (55.8% and 30.6% for countries with PCV10 and PCV13 in the pediatric NIP), most commonly serotypes 3 (14.9%) and 19A (7.0%). PCV15 and PCV20 would cover an additional 10.4% and 32.9% of older adult IPD beyond PCV13 serotypes (PCV10 countries: 7.7% and 23.3%; PCV13 countries: 10.6% and 34.6%). The most common of these additional serotypes were 8 (9.9%), 22F (7.9%), 12F (4.6%), and 11A (3.3%). PPSV23 policies for older adults were not correlated with lower IPD percentages due to PPSV23 serotypes. Vaccinating older adults with higher-valency PCVs, especially PCV20, could substantially reduce the remaining IPD burden in high-income countries, regardless of current PCV use in pediatric NIPs and adult PPSV23 policies.

•The Canadian pediatric PCV13 programs reduced PCV13-serotype IPD cases in all ages.•Decreases in PCV13-serotype IPD cases have plateaued since 2014.•Decreases were most prominent in children aged <5 years compared with other ages.•Further reductions may require increased PCV13 uptake in children and adults.•Next-generation PCVs may help further reduce pneumococcal disease in Canada. In 2010–2011, the 13-valent pneumococcal conjugate vaccine (PCV13) replaced the 7- or 10-valent vaccine (PCV7 and PCV10, respectively) in pediatric immunization programs across Canada. For adults aged ≥65 years, the 23-valent pneumococcal polysaccharide vaccine (PPSV23) has been publicly funded for several decades; PCV13 funding was not recommended in this population, partly due to expected ongoing vaccine-serotype disease decline stemming from herd effects of the pediatric program. Higher-valent PCVs (ie, 15- and 20-valent PCVs [PCV15 and PCV20, respectively]) currently in development may become available in Canada in the coming years. Using the National Microbiology Laboratory surveillance reports, annual case counts and serotype distribution of invasive pneumococcal disease (IPD) from 2010 to 2017 in Canada were examined to assess the impact of existing programs on PCV13-serotype IPD and determine the proportion of IPD that can potentially be prevented by current and forthcoming higher-valent PCVs. The percentages of PCV13-serotype IPD decreased from 55% [1492/2708] in 2010 to 30% [902/3006] in 2017 in all age groups combined, including a decline from 67% [221/331] to 18% [40/219] in children aged <5 years and from 50% [487/967] to 23% [287/1238] in adults aged ≥65 years. Overall, IPD cases declined mainly before 2014 and have plateaued since then. In 2017, PCV15- and PCV20-serotypes (inclusive of PCV13 serotypes) accounted for 42% and 58% of IPD cases, respectively, in all ages. In Canada, publicly funded pediatric PCV13 use was associated with large declines in IPD due to vaccine serotypes. Substantial residual PCV13-serotype IPD proportions observed among all ages imply limits to indirect protection afforded by the pediatric PCV13 program at the current uptake level and suggest the adult PPSV23 program alone is insufficient. Higher-valent PCVs have the potential to address a substantial proportion of remaining IPD cases among all age groups.

We studied the impact of 13-valent pneumococcal conjugate vaccine (PCV13) on the incidence of invasive pneumococcal disease (IPD) and serotype distribution in a region with intermediate levels of vaccination (around 64% in children aged <2 years). Surveillance data on IPD cases reported by microbiologists participating in the Microbiological Reporting System of Catalonia during 2006–2014 were analysed. We compared estimated incidence rate (IR) ratios for serotypes included in PCV7, PCV10non7, PCV13non10 and non-PCV13 between the PCV7 (2006–2009) and PCV13 periods (2010–2014). IR were corrected for missing serotypes according to year and age groups: <2 years, 2–4 years, 5–64 years and ≥65 years. A total of 9338 IPD cases were reported. Overall IPD incidence declined by 26.2% (from 16.4 to 12.1) in the PCV13 period. The largest decrease was observed in children aged 2–4 years (44.5%, from 37.4 to 20.8). Pneumonia fell in all age groups with the largest reduction in children aged 2–4 years (49.3%) and <2 years (42%). PCV13 serotypes decreased significantly in all age groups, from 52% (31.6 to 15.1) in children aged 2–4 years to 35% (22.8 to 14.8) in adults aged ≥65 years. Non-PCV13 serotypes rose by 13% (14.8 to 16.8) in people aged ≥65 years. In a region with intermediate vaccination coverage, the introduction of PCV13 has reduced the overall incidence of IPD, mainly due to the decrease in PCV13 serotypes in all age groups, suggesting herd immunity. Non-PCV13 serotypes have increased in adults aged ≥65 years, suggesting serotype replacement. Higher PCV13 vaccination coverage in children will further reduce IPD incidence in all age groups.

Pneumococcal conjugate vaccine (PCV) introduction has reduced pneumococcal meningitis incidence. The Pneumococcal Serotype Replacement and Distribution Estimation (PSERENADE) project described the serotype distribution of remaining pneumococcal meningitis in countries using PCV10/13 for least 5–7 years with primary series uptake above 70%. The distribution was estimated using a multinomial Dirichlet regression model, stratified by PCV product and age. In PCV10-using sites (N = 8; cases = 1141), PCV10 types caused 5% of cases <5 years of age and 15% among ≥5 years; the top serotypes were 19A, 6C, and 3, together causing 42% of cases <5 years and 37% ≥5 years. In PCV13-using sites (N = 32; cases = 4503), PCV13 types caused 14% in <5 and 26% in ≥5 years; 4% and 13%, respectively, were serotype 3. Among the top serotypes are five (15BC, 8, 12F, 10A, and 22F) included in higher-valency PCVs under evaluation. Other top serotypes (24F, 23B, and 23A) are not in any known investigational product. In countries with mature vaccination programs, the proportion of pneumococcal meningitis caused by vaccine-in-use serotypes is lower (≤26% across all ages) than pre-PCV (≥70% in children). Higher-valency PCVs under evaluation target over half of remaining pneumococcal meningitis cases, but questions remain regarding generalizability to the African meningitis belt where additional data are needed.

Background Pneumococcal conjugate vaccines (PCV7/10/13) have reduced vaccine-serotype disease and resistance globally, including indirect effects in unvaccinated populations. Nigeria introduced PCV10 in 2016, but its impact on serotype distribution and resistance in Delta State remains poorly defined. Aim To determine the prevalence of Streptococcus pneumoniae , the circulating serotypes, and their antimicrobial susceptibility patterns among children and adults ~ 3 years post PCV10 introduction in Delta State, Nigeria. Methods We processed 622 clinical specimens (July 2019–November 2020) from two hospitals. Isolates with α-hemolysis and optochin susceptibility were confirmed as pneumococci by multiplex PCR targeting cpsA. Serotyping used a multiplex PCR panel covering PCV13 serotypes. Antimicrobial susceptibility testing was by Kirby–Bauer disk diffusion; S/I/R (Susceptibility/Intermediate/Resistance) categories were assigned only for agents with validated disk-diffusion breakpoints in S. pneumoniae (erythromycin, clindamycin, tetracycline, levofloxacin, trimethoprim–sulfamethoxazole). Because neither oxacillin screening nor MIC testing was performed, β-lactams, imipenem, and vancomycin were reported as inhibition-zone diameters without categorical interpretation. Results Of 622 specimens, 8 (1.3%) yielded phenotypic pneumococci; 5/8 (62.5%) were cpsA-positive, all from non-invasive specimens. By age, 3/5 (60%) were from adults ≥ 61 years, and 1/5 each from 11 to 20 and 21–40 years. All five isolates were non-vaccine types (non-PCV13); specific serotypes were not resolved. Among drugs with validated disk-diffusion breakpoints, 4/5 (80%) isolates were susceptible to erythromycin, clindamycin, and levofloxacin; all 5/5 (100%) were non-susceptible to trimethoprim–sulfamethoxazole; and 3/5 (60%) were non-susceptible to tetracycline. Using a non-β-lactam definition, multidrug resistance (MDR) was detected in 1/5 (20%) isolates. Conclusion In this two-site survey, pneumococci were infrequently recovered and comprised non-vaccine types that largely retained susceptibility to macrolide, lincosamide, and fluoroquinolone agents, alongside uniform non-susceptibility to trimethoprim–sulfamethoxazole and sporadic MDR. Although numbers are small, these findings support continued serotype-specific and resistance surveillance incorporating MIC testing and molecular typing to track serotype replacement, clarify resistance mechanisms, and evaluate the longer-term impact of PCV10 in Delta State, Nigeria.

Background The incidence of invasive pneumococcal disease (IPD) varies depending on a number of factors, including vaccine uptake, in both children and adults, the geographic location, and local serotype prevalence. There are limited data about the burden of  Streptococcus pneumoniae ( Spn ), serotype distribution, and clinical characteristics of adults hospitalized due to IPD in Colombia. The objectives of this study included assessment of Spn serotype distribution, clinical characteristics, mortality, ICU admission, and the need for mechanical ventilation. Methods This was an observational, retrospective, a citywide study conducted between 2012 and 2019 in Bogotá, Colombia. We analyzed reported positive cases of IPD from 55 hospitals in a governmental pneumococcal surveillance program. Pneumococcal strains were isolated in each hospital and typified in a centralized laboratory. This is a descriptive study stratified by age and subtypes of IPD obtained through the analysis of medical records. Results A total of 310 patients with IPD were included, of whom 45.5% were female. The leading cause of IPD was pneumonia (60%, 186/310), followed by meningitis. The most frequent serotypes isolated were 19A (13.87%, 43/310) and 3 (11.94%, 37/310). The overall hospital mortality rate was 30.3% (94/310). Moreover, 52.6% (163/310 patients) were admitted to the ICU, 45.5% (141/310) required invasive mechanical ventilation and 5.1% (16/310) non-invasive mechanical ventilation. Conclusion Pneumococcal pneumonia is the most prevalent cause of IPD, with serotypes 19A and 3 being the leading cause of IPD in Colombian adults. Mortality due to IPD in adults continues to be very high.

Background Approximately 100 capsular serotypes of S. pneumonia have been identified according to the composition of their capsular polysaccharides, currently available vaccines do not cover many of these. Pneumococcal vaccination serotype coverage is essential for preventing noninvasive and invasive illnesses as well as asymptomatic carriage. We aimed to determine the serotype distribution and antimicrobial susceptibility pattern of pneumococcal clinical isolates in this study. We also analyzed the serotype coverage rates of PCV13, which is applied in the NIP, and PCV-15 and PCV20, which have been introduced recently. Methods This study is a retrospective surveillance of pneumococcal infections including invasive pneumococcal isolates (IPIs) and non-invasive pneumococcal isolates (non-IPIs). Results A total of 420 isolates from 356 different patients aged 0–89 years were enrolled in the study. A total of 420 pneumococcal isolates were serotyped and 26 different serotypes were detected. Serotype 19 F was the most prevalent serotype ( n  = 96, 22.8%), followed by 6 A/B ( n  = 55, 13.1%), 23 F ( n  = 49, 11.6%), 3 ( n  = 22, 5.2%) and 19 A ( n  = 16, 3.8%). Conclusions Surveillance studies of pneumococcal diseases are critical to investigating current serotype distributions, antibiotic resistance status, and frequency of IPD cases. Considering the increasing antibiotic resistance rates of S. pneumoniae , it is necessary to provide protective immunization by switching to more comprehensive PCV vaccines rather than treatment. Clinical trial number Not applicable.

Background Group B Streptococcus (GBS) bacteremia in nonpregnant adults is of increasing concern, particularly among the elderly in underlying conditions. This study analyzed the serotype distribution, antimicrobial resistance patterns, and clinical characteristics of GBS bacteremia in nonpregnant adults over a 15-year period in two tertiary hospitals in Korea. Methods From 2007 to 2021, patients aged ≥ 19 years with GBS bacteremia were identified via retrospective electronic medical record review. GBS isolates were collected through a hospital-wide surveillance system and confirmed via MALDI-TOF-MS. Multilocus sequence typing (MLST) was conducted for serotype VIII and undetermined serotype isolates. Clinical and laboratory data were analyzed to assess trends and mortality risk factors. Results A total of 264 episodes of GBS bacteremia were identified, with 147 isolates successfully re-cultured and 125 isolates and patients included in the clinical characteristic analysis. Serotype VIII emerged as the most common serotype (42.1% in 2019–2021) with a significant increase in prevalence over time ( P  = 0.02). MLST of serotype VIII revealed ST2 as the dominant sequence type (87.8%). Antimicrobial resistance rates for erythromycin, clindamycin, and levofloxacin were 27.2%, 30.4%, and 23.2%, respectively, with notable variability among serotypes. The 30-day mortality rate was 12.8%. Male sex (aOR: 2.18; 95% CI: 1.15–4.13, P  = 0.02) and SOFA score (aOR per unit increase: 1.25; 95% CI: 1.12–1.38, P  < 0.001) were significantly associated with mortality. Conclusions This study highlights the emergence of serotype VIII as a predominant cause of GBS bacteremia and its association with ST2 in South Korea. Male sex and higher SOFA scores were independent risk factors for mortality. The findings emphasize the need for ongoing surveillance and consideration of serotype-specific strategies in clinical management and vaccine development.