Prevalence, capsular types, antimicrobial resistance and risk factors associated with pneumococcal carriage among children after long-term 10-valent pneumococcal conjugate vaccine use in Brazil

Changes in population genetic structure of serotype 19A Streptococcus pneumoniae after universal childhood use of the 10-valent pneumococcal conjugate vaccine in Brazil

BACKGROUND

The introduction of the 10-valent pneumococcal conjugate vaccine (PCV10) for nationwide childhood immunization in 2010 led to a significant reduction in colonization and invasive pneumococcal disease (IPD) by vaccine serotypes in young. However, non-vaccine serotypes have emerged, and serotype 19A is now the leading cause of IPD in Brazil.

METHODS

We analyzed 32 serotype 19A isolates of Streptococcus pneumoniae recovered from children and adults who attended different health facilities in the state of Rio de Janeiro, Brazil, between 2010 and 2023. The capsular types of the isolates were determined by sequential multiplex PCR or by cpsB gene sequencing. All isolates were subjected to antimicrobial susceptibility testing and MLST.

RESULTS

Of the 32 serotype 19A isolates, 29 (90.6 %) isolates were recovered from children aged ≤5 years and three (9.4 %) isolates were recovered from adults. Nineteen (59.4 %) isolates were associated with colonization, and 13 (40.6 %) isolates were from diseases. All isolates were susceptible to chloramphenicol, levofloxacin, linezolid, rifampin, and vancomycin. The highest frequencies of non-susceptibility (intermediate + resistant) were observed for sulfamethoxazole-trimethoprim (n = 30; 93.8 %), penicillin (n = 24; 75 %), and erythromycin (n = 23; 71.9 %). Twenty-two (68.8 %) isolates were multidrug resistant (MDR). MICs for penicillin among penicillin-non-susceptible pneumococci (PNSP) ranged from 0.12 to 8.0 μg/mL. MICs for erythromycin ranged from 0.064 to >256 μg/mL. MICs for ceftriaxone ranged from 0.023 to 4 μg/mL. The most common genetic lineages were ST733 (n = 7; 21.9 %), mostly found before and in the early years of PCV10 introduction, and CC320 (n = 25; 78.1 %), mostly found in the late-PCV10 period. All 25 isolates within CC320 were PNSP and mostly (n = 22; 88 %) MDR.

CONCLUSIONS

We observed a shift in antimicrobial susceptibility profiles and genetic lineages after long-term use of PCV, mostly PCV10, for routine childhood immunization, characterized by clonal expansion of the MDR lineage CC320.

Long-term predominance in childhood colonization of the multidrug-resistant lineage 6C/ST386 of Streptococcus pneumoniae after universal immunization with the 10-valent pneumococcal conjugate vaccine in Brazil

BACKGROUND

A study conducted in the city of Niterói/RJ, four years after the introduction of the pneumococcal conjugate vaccine in Brazil, reported the emergence of non-vaccine serotype 6C Streptococcus pneumoniae associated with carriage in children. The multidrug-resistant (MDR) lineage ST386 was predominant among 6C isolates. A subsequent study, in 2019, reported the continued prevalence of 6C as the main serotype. This study aims to determine the genetic lineages of serotype 6C S. pneumoniae obtained from the 2019 study and evaluate the status of ST386 in this population.

METHODS

Serotype 6C S. pneumoniae isolates were obtained during the 2019 study. Lineages were determined by MLST and changes in ST386 status between 2014 and 2019 were verified by a two-tailed Fisher's exact test.

RESULTS

Of the 16 serotype 6C isolates recovered during 2019, 10 (62.5 %) belonged to ST386, remaining predominant in the population. The second most frequent was ST2777 represented by four (25 %) isolates. Both ST63 and ST3280 only had one (6.25 %) isolate each. Comparison of ST386 proportion between 2014 and 2019 showed no significant changes within the population.

CONCLUSIONS

This study was able to confirm the stability on the occurrence of the MDR lineage ST386 in children in our setting nine years after the introduction of PCV10 in Brazil.

Upper respiratory Streptococcus pneumoniae colonization among working-age adults with prevalent exposure to overcrowding

Most pneumococcal disease occurs among infants and older adults and is thought to be driven by the transmission of Streptococcus pneumoniae from young children to these vulnerable age groups. However, pneumococcal disease outbreaks also affect non-elderly adults living or working in congregate, close-contact settings. Little is known about pneumococcal carriage in such populations. From July to November 2020, we collected saliva from low-income adult farmworkers in Monterey County, California, and tested for pneumococcal carriage following culture enrichment via quantitative PCR assays targeting the pneumococcal lytA and piaB genes. Participants were considered to carry pneumococci if lytA and piaB cycle threshold values were both below 40. Among 1,283 participants enrolled in our study, 117 (9.1%) carried pneumococci. Carriers tended more often than non-carriers to be exposed to children aged <5 years [odds ratio (OR) = 1.45 (0.95-2.20)] and overcrowding [OR = 1.48 (0.96-2.30) and 2.84 (1.20-6.73), respectively, for participants in households with >2-4 and >4 persons per bedroom vs ≤2 persons per bedroom]. Household overcrowding remained associated with increased risk of carriage among participants not exposed to children aged <5 years [OR = 2.05 (1.18-3.59) for participants living in households with >2 vs ≤2 persons per bedroom]. Exposure to children aged <5 years and overcrowding were each associated with increased pneumococcal density among carriers [piaB cT difference of 2.04 (0.36-3.73) and 2.44 (0.80-4.11), respectively]. While exposure to young children was a predictor of pneumococcal carriage, associations of overcrowding with increased prevalence and density of carriage in households without young children suggest that transmission also occurs among adults in close-contact settings.IMPORTANCEAlthough infants and older adults are the groups most commonly affected by pneumococcal disease, outbreaks are known to occur among healthy, working-age populations exposed to overcrowding, including miners, shipyard workers, military recruits, and prisoners. Carriage of Streptococcus pneumoniae is the precursor to pneumococcal disease, and its relation to overcrowding in adult populations is poorly understood. We used molecular methods to characterize pneumococcal carriage in culture-enriched saliva samples from low-income adult farmworkers in Monterey County, CA. While exposure to children in the household was an important risk factor for pneumococcal carriage, living in an overcrowded household without young children was an independent predictor of carriage as well. Moreover, participants exposed to children or overcrowding carried pneumococci at higher density than those without such exposures, suggesting recent transmission. Our findings suggest that, in addition to transmission from young children, pneumococcal transmission may occur independently among adults in overcrowded settings.

Nasopharyngeal carriage of Streptococcus pneumoniae in Latin America and the Caribbean: A systematic review and meta-analysis

BACKGROUND

Streptococcus pneumoniae is a leading cause of morbidity and mortality globally, causing bacteremic pneumonia, meningitis, sepsis, and other invasive pneumococcal diseases. Evidence supports nasopharyngeal pneumococcal carriage as a reservoir for transmission and precursor of pneumococcal disease.

OBJECTIVES

To estimate the pneumococcal nasopharyngeal burden in all age groups in Latin America and the Caribbean (LAC) before, during, and after the introduction of pneumococcal vaccine conjugate (PVC).

METHODS

Systematic literature review of international, regional, and country-published and unpublished data, together with reports including data from serotype distribution in nasopharyngeal carriage in children and adults from LAC countries following Cochrane methods. The protocol was registered in PROSPERO database (ID: CRD42023392097).

RESULTS

We included 54 studies with data on nasopharyngeal pneumococcal carriage and serotypes from 31,803 patients. In children under five years old, carriage was found in 41% and in adults over 65, it was 26%. During the study period, children under five showed a colonization proportion of 34% with PCV10 serotypes and 45% with PCV13 serotypes. When we analyze the carriage prevalence of PCV serotypes in all age groups between 1995 and 2019, serotypes included in PCV10 and those included in PCV13, both showed a decreasing trend along analysis by lustrum.

CONCLUSION

The data presented in this study highlights the need to establish national surveillance programs to monitor pneumococcal nasopharyngeal carriage to monitor serotype prevalence and replacement before and after including new pneumococcal vaccines in the region. In addition, to analyze differences in the prevalence of serotypes between countries, emphasize the importance of approaches to local realities to reduce IPD effectively.

Global trends in non-susceptibility rates of Streptococcus pneumoniae isolates to ceftriaxone: Data from the antimicrobial testing leadership and surveillance (ATLAS) programme, 2016-21

To understand the global changes in non-susceptibility rates of Streptococcus pneumoniae to ceftriaxone, we conducted a study using the Antimicrobial Testing Leadership and Surveillance database. A total of 15,717 S. pneumoniae isolates were collected from 2016 to 2021. The minimum inhibitory concentrations (MICs) were determined using broth microdilution. The overall susceptibility rates of S. pneumoniae isolates to penicillin, ceftriaxone and ceftaroline were 63.4%, 94.0% and 99.6%, respectively. The geometric mean of MICs and MIC50/MIC90 values of ceftriaxone were higher in Asia than in other continents. China (33.9%), South Korea (33.8%) and Taiwan (27.6%) had the highest ceftriaxone non-susceptibility rates, followed by Turkey, India, Brazil, Malaysia, South Africa and Colombia, with rates between 10% and 20%. During the study period from 2020 to 2021, Asia had the highest MIC90 value (4 mg/L) for ceftriaxone in S. pneumoniae isolates, and the geometric mean of MICs increased from 0.25 mg/L in 2016-2017 to 0.39 mg/L in 2020-2021. Both Asia (from 83.4% to 75.1%) and Latin America (from 94.2% to 86.3%) showed a decreasing trend in ceftriaxone susceptibility rates from 2016 to 2021. In North America, Europe and Oceania, the susceptibility rate was higher than 95%, and there was no obvious change in the rate during the 6 y. Further analysis of the data from Asia revealed that individuals younger than 6 y of age had a lower susceptibility rate to ceftriaxone (71.6% vs. 81.7%, P < 0.05) than patients ≥6 y. The higher non-susceptibility rates of ceftriaxone in S. pneumoniae in Asia may lead to therapeutic challenges in community-acquired pneumonia.

Antimicrobial Resistance in Streptococcus pneumoniae before and after the Introduction of Pneumococcal Conjugate Vaccines in Brazil: A Systematic Review

Streptococcus pneumoniae causes serious illnesses, such as pneumonia, bacteremia, and meningitis, mainly in immunocompromised individuals and those of extreme ages. Currently, pneumococcal conjugate vaccines (PCVs) are the best allies against pneumococcal diseases. In Brazil, the 10-valent and 13-valent PCVs have been available since 2010, but the threat of antimicrobial resistance persists and has been changing over time. We conducted a systematic review of the literature with works published since 2000, generating a parallel between susceptibility data on isolates recovered from colonization and invasive diseases before and after the implementation of PCVs for routine childhood use in Brazil. This systematic review was based on the Cochrane Handbook for Systematic Reviews of Interventions and Preferred Reporting Items for Systematic Literature Reviews and Meta-Analyses (PRISMA) guidelines. Despite the inclusion of PCVs at a large scale in the national territory, high frequencies of non-susceptibility to important drugs used in pneumococcal diseases are still observed, especially penicillin, as well as increasing resistance to macrolides. However, there are still drugs for which pneumococci have a comprehensive sensitivity profile.