The Pneumococcus and Its Critical Role in Public Health

RNA cis-regulators are important for Streptococcus pneumoniae in vivo success

Bacteria have evolved complex transcriptional regulatory networks, as well as many diverse regulatory strategies at the RNA level, to enable more efficient use of metabolic resources and a rapid response to changing conditions. However, most RNA-based regulatory mechanisms are not well conserved across different bacterial species despite controlling genes important for virulence or essential biosynthetic processes. Here, we characterize the activity of, and assess the fitness benefit conferred by, twelve cis-acting regulatory RNAs (including several riboswitches and a T-box), in the opportunistic pathogen Streptococcus pneumoniae TIGR4. By evaluating native locus mutants of each regulator that result in constitutively active or repressed expression, we establish that growth defects in planktonic culture are associated with constitutive repression of gene expression, while constitutive activation of gene expression is rarely deleterious. In contrast, in mouse nasal carriage and pneumonia models, strains with either constitutively active and repressed gene expression are significantly less fit than matched control strains. Furthermore, two RNA-regulated pathways, FMN synthesis/transport and pyrimidine synthesis/transport display exceptional sensitivity to mis-regulation or constitutive gene repression in both planktonic culture and in vivo environments. Thus, despite lack of obvious phenotypes associated with constitutive gene expression in vitro, the fitness benefit conferred on bacteria via fine-tuned metabolic regulation through cis-acting regulatory RNAs is substantial in vivo, and therefore easily sufficient to drive the evolution and maintenance of diverse RNA regulatory mechanisms.

Antibiotic resistance pattern, capsular types, and molecular characterization of invasive isolates of Streptococcus pneumoniae in the south of Tunisia from 2012 to 2018

BACKGROUND

Streptococcus pneumoniae remains a leading cause of morbidity and mortality worldwide. In this study, we sought to analyze serotype distributions, antibiotic resistance, and genetic relationships of 106 clinical invasive pneumococcal isolates recovered in Tunisia between 2012 and 2018, prior to the routine use of pneumococcal conjugate vaccines (PCV).

METHODS

We used multiplex PCR, the disk diffusion method and/or E-test, and multi-locus sequence typing (MLST).

RESULTS

The most frequent serotypes were 14 (17%), 19F (14.2%), and 3 (11.3%). Of the 106 S. pneumoniae isolates, 67.9% were penicillin non-susceptible (29.4% were resistant), 45.3% were amoxicillin non-susceptible (17% were resistant), and 16% were cefotaxime non-susceptible. For antibiotics other than β-lactams, resistance rates to erythromycin, tetracycline, cotrimoxazole, and chloramphenicol were 62.3, 33, 22.6, and 4.7%, respectively. Two isolates were non-susceptible to levofloxacin. Among 66 erythromycin-resistant pneumococci, 77.3% exhibited the cMLSB phenotype, and 87.9% carried ermB gene. All tetracycline-resistant strains harbored the tetM gene. The potential coverage by 7-, 10-, and 13-valent pneumococcal conjugate vaccines were 55.7, 57.5, and 81.1%, respectively. A multilocus sequence typing analysis revealed great diversity. Fifty different sequence types (STs) were identified. These STs were assigned to 10 clonal complexes and 32 singletons. The most common STs were 179, 2918, 386, and 3772 - related mainly to 19F, 14, 6B/C, and 19A serotypes, respectively.

CONCLUSIONS

This study demonstrated that the majority of the serotypes of invasive pneumococci in the Tunisian population were 14, 19F, and 3. Moreover, we noted a high degree of genetic diversity among invasive S. pneumoniae isolates. The highest proportions of antibiotic non-susceptible isolates were for penicillin, erythromycin, and tetracycline. Further molecular characteristics are required to monitor the genetic variations and to follow the emergence of resistant pneumococci for the post-vaccination era in Tunisia.

A Hospital-Based and Cross-Sectional Investigation on Clinical Characteristics of Pediatric Streptococcus pneumoniae Isolates in Beijing from 2015 to 2021

Introduction

Streptococcus pneumoniae (S. pneumoniae) is a major pathogen causing death in children. Few studies have evaluated the importance of S. pneumoniae in the identified bacteria in clinical work. This retrospective study aimed to reveal the rank of S. pneumoniae in determined bacteria isolated from children in Beijing, China, as well as the antimicrobial resistance of this pathogen.

Methods

The number of specimen for bacterial culture and of bacterial species were cumulated and ranked based on the data of the two largest children's hospitals in Beijing from 2015 to 2021. The temporal change of S. pneumoniae culture, as well as the clinical data of S. pneumoniae isolates were collected and analyzed. The minimum inhibitory concentrations of antimicrobial agents were determined by BD Phoenix 100 automated system or Vitek 2 automated system for antimicrobial susceptibility testing. The breakpoints recommended by CLSI were adopted.

Results

During the 7-year study period, a total of 45,631 bacterial isolates were cultured from 462,144 submitted specimens, in which S. pneumoniae was the third frequent agent following S. aureus and H. influenza, and accounting for 8.79% of the isolates (4011/45,631). In the 4011 S. pneumoniae isolates, 2239 and 997 ones were, respectively, isolated from sputum and bronchial lavage fluid. Most of S. pneumoniae strains were identified in winter (34.7%) and spring (26.1%), and were mainly isolated from patients under 5 years old (77.1%). Low susceptible rate (27.6%) of CSF isolates was determined to penicillin according to the parenteral meningitis breakpoints, while high susceptible rate (56.9%) of non-CSF isolates was obtained according to the parenteral non-meningitis breakpoints. The isolates showed low sensitivity to erythromycin and tetracycline (<5%). All isolates were susceptible to vancomycin and linezolid.

Conclusion

The present results demonstrated that S. pneumoniae was one of the most commonly detected bacteria in current pediatric clinical tests, especially in young children under 5 years old, which emphasized the importance of prevention. Penicillin could still be the first empiric choice to treat non-meningitis pneumococcal infections, while erythromycin should not be involved in the treatment.

Molecular Characterization of Predominant Serotypes, Drug Resistance, and Virulence Genes of Streptococcus pneumoniae Isolates From East China

Streptococcus pneumoniae is a common diplococcus pathogen found worldwide. The characterization of predominant serotypes, drug resistance, and virulence genes of S. pneumoniae isolates prevailing in different areas and countries is clinically important for choice of antibiotics and improvement of vaccines. In this study, pneumonia (78.7%) and meningitis (37.0%) were the predominant diseases observed in the 282 (children) and 27 (adults) S. pneumoniae-infected patients (p < 0.05) from seven hospitals in different areas of East China. Of the 309 pneumococcal isolates, 90.3% were classified by PCR into 15 serotypes, with serotypes 19F (27.2%) and the 6A/B (19.1%) being most predominant (p < 0.05). Importantly, serotypes 15A and 15B/C combined for a total of 10.4% of the isolates, but these serotypes are not included in the 13-valent pneumococcal capsule conjugate vaccine used in China. Antimicrobial susceptibility analysis by the E-test showed that >95% of the 309 pneumococcal isolates were susceptible to moxifloxacin and levofloxacin, as well as 18.4, 85.8, and 81.6% of the isolates displayed susceptibility to penicillin, cefotaxime, and imipenem, respectively. A significant correlation between the prevalence of predominant serotypes and their penicillin resistance was observed (p < 0.05). In particular, >95% of all the pneumococcal isolates showed resistance to erythromycin and azithromycin. Of the nine detected virulence genes, the lytA, ply, hysA, and nanA were the most common with 95–100% positive rates in the 309 pneumococcal isolates, while the pavA and psaA genes displayed a significant correlation with pneumococcal bacteremia and meningitis (p < 0.05). Overall, our data suggested that the predominant serotypes, drug resistance, and virulence genes of the S. pneumoniae isolates prevailing in East China are distinct from those observed in other areas of China and adjacent countries.

Effect of prophylactic administration of antipyretics on the immune response to pneumococcal conjugate vaccines in children: a systematic review

Background

Prophylactic administration of antipyretics at the time of immunization seems to decrease some side effects, however reduced immune responses have been reported in some studies. This systematic review aimed to investigate the effect of prophylactic use of antipyretics on the immune response following administration of pneumococcal conjugate vaccines (PCVs).

Methods

A systematic review of randomized controlled trials and observational studies concerning the immune response to PCVs after antipyretic administration was performed up to November 2020 in the electronic databases of Pubmed and Scopus.

Results

Of the 3956 citations retrieved, a total of 5 randomized control trials including 2775 children were included in the review. Included studies were referred to PCV10 (3 studies), PCV7 and PCV13 (one study each). The prophylactic administration of paracetamol decreased the immune response to certain pneumococcal serotypes in all included studies. The effect was more evident following primary vaccination and with immediate administration of paracetamol. Despite the reductions in antibody geometric mean concentrations, a robust memory response was observed following the booster dose. Besides, antibody titers remained above protective levels in 88–100% of participants. The use of ibuprofen, that was evaluated in two studies, did not seem to affect the immunogenicity of PCVs .

Conclusion

Although the reviewed studies had significant heterogeneity in design, paracetamol administration seems to affect the immune response for certain serotypes. The clinical significance of reduced immunogenicity especially before booster dose needs further investigation.

Improving population health in resident clinics: increasing pneumonia vaccination rates in adults 65 years and older

Streptococcus pneumoniae is a significant bacterial pathogen, especially in the elderly. There are two types of pneumococcal vaccines, one with polysaccharides from the capsule of 23 serotypes (PPSV23) and one with polysaccharides from 13 serotypes that have been conjugated to a protein (PCV13). Both vaccines decrease the incidence of invasive pneumococcal disease and are recommended for all people ≥65 years of age. We found the vaccination rate against S. pneumoniae in patients ≥65 years of age in our resident physician continuity clinics was 59.85%, which is considerably lower than the vaccination rate of 69.16% in our attending physician clinics. The aim of our study was to double the number of vaccinations given in the resident physician clinics over a 1-month period without compromising workflow or unduly burdening the rooming nurse or resident physicians. For our primary intervention, we assigned a designated nurse with expertise in vaccinations the task of reviewing charts ahead of clinic visits then pending the order for the appropriate pneumococcal vaccine. Our secondary intervention was the education of physicians through pocket cards, verbal encouragement and email reminders. χ² test was conducted to compare the proportion of patients 65 years or older who were vaccinated between the intervention and control groups. The results indicated that the intervention group patients were 2.61 times (95% CI 1.18 to 6.10) more likely to be vaccinated compared with the control group patients (20% vs 8.7%, χ² (1)=5.16, p=0.02, Cramer’s V=0.16). The intervention resulted in more than doubling the number of vaccinations in the intervention group compared with the control group. Moreover, poststudy interviews and surveys indicated our workflow is sustainable and amendable to wider use within the resident physician clinics.

Summary of evidence to reduce the two-dose infant priming schedule to a single dose of the 13-valent pneumococcal conjugate vaccine in the national immunisation programme in the UK

Pneumococcal conjugate vaccines (PCVs) are highly effective in preventing invasive and non-invasive pneumococcal infections in all age groups through a combination of direct and indirect protection. In many industrialised countries with established PCV programmes, the maximum benefit of the PCV programme has already been achieved, with most cases now due to non-PCV serotypes. On Jan 1, 2020, the UK changed its childhood pneumococcal immunisation programme from a two-dose infant priming schedule with the 13-valent PCV at 8 and 16 weeks after birth, to a single priming dose at 12 weeks after birth, while retaining the 12-month booster. This decision was made after reviewing the evidence from surveillance data, clinical trials, epidemiological analyses, vaccine effectiveness estimates, and modelling studies to support the reduced schedule. In this Review, we summarise the epidemiology of pneumococcal disease in the UK, the evidence supporting the decision to implement a reduced schedule, and the national and global implications of the proposed schedule.