Changes in Serotype of Streptococcus pneumoniae After the Introduction of the 13-Valent Pneumococcal Vaccine in a Homogenous Population on Jeju Island

Invasive Pneumococcal Diseases in Korean Adults After the Introduction of Pneumococcal Vaccine into the National Immunization Program

Although Streptococcus pneumoniae has been one of the most common bacterial causes of disease in humans, its impact has been blunted by the broad use of vaccines. Since 2018, the incidence of invasive pneumococcal disease in Korea decreased with effective pneumococcal vaccines but is on the rise again recently. In this paper I will review the epidemiology, risk factors, and antibiotic resistance of invasive pneumococcal disease after the introduction of the pneumococcal vaccine in Korean adults.

The serotype-specific prevalence of pneumococci in hospitalized pneumonia patients with COPD: a prospective, multi-center, cohort study

BACKGROUND/AIMS

The overall incidence of pneumococcal pneumonia is declining. However, the change in the pathogenic distribution of community-acquired pneumonia (CAP) in chronic obstructive pulmonary disease (COPD) patients and the serotype specificity of Streptococcus pneumoniae have not been evaluated in the post-era of pneumococcal vaccination in Korea.

METHODS

We conducted a prospective, multi-center, cohort study from seven University-affiliated hospitals. The primary objective was the identification of serotype-specific prevalence of pneumococcal pneumonia in COPD patients hospitalized for CAP. For the purpose, we conducted serotype-specific urine antigen detection (SS-UAD) assays for S. pneumoniae. The secondary objectives were other clinical characteristics of pneumonia including vaccination status.

RESULTS

The total number of participants was 349. Most of them were male (95.1%) with old ages (75.55 ± 8.59 y). The positive rate for S. pneumoniae was 9.2% with SS-UAD assay and the common serotypes were 22F, 6A, and 6B. In the sputum, Pseudomonas aeruginosa (5.0%) and Haemophilus influenzae (4.0%) were common pathogens. The vaccination rate was 78.8%, 53.0%, and 25.8% for influenza, pneumococcal polysaccharide vaccine 23 (PPV 23), and pneumococcal protein- conjugated vaccine 13 (PCV 13), respectively. Thirteen patients died during hospitalization (mortality rate; 3.7%). There was no difference in the respective rate of influenza vaccination (79.2% vs. 69.2%, p = 0.288) and PCV 13 vaccination (25.6% vs. 30.8%, p = 0.443) between survivors and the deceased.

CONCLUSION

Serotypes 22F, 6A, and 6B, which are covered either by PPV 23 or by PCV 13, are still common pneumococcal serotypes in COPD pneumonia in the post-vaccination era in Korea.

The Molecular Approaches and Challenges of Streptococcus pneumoniae Serotyping for Epidemiological Surveillance in the Vaccine Era

Streptococcus pneumoniae (pneumococcus) belongs to the Gram-positive cocci. This bacterium typically colonizes the nasopharyngeal region of healthy individuals. It has a distinct polysaccharide capsule - a virulence factor allowing the bacteria to elude the immune defense mechanisms. Consequently, it might trigger aggressive conditions like septicemia and meningitis in immunocompromised or older individuals. Moreover, children below five years of age are at risk of morbidity and mortality. Studies have found 101 S. pneumoniae capsular serotypes, of which several correlate with clinical and carriage isolates with distinct disease aggressiveness. Introducing pneumococcal conjugate vaccines (PCV) targets the most common disease-associated serotypes. Nevertheless, vaccine selection pressure leads to replacing the formerly dominant vaccine serotypes (VTs) by non-vaccine types (NVTs). Therefore, serotyping must be conducted for epidemiological surveillance and vaccine assessment. Serotyping can be performed using numerous techniques, either by the conventional antisera-based (Quellung and latex agglutination) or molecular-based approaches (sequetyping, multiplex PCR, real-time PCR, and PCR-RFLP). A cost-effective and practical approach must be used to enhance serotyping accuracy to monitor the prevalence of VTs and NVTs. Therefore, dependable pneumococcal serotyping techniques are essential to precisely monitor virulent lineages, NVT emergence, and genetic associations of isolates. This review discusses the principles, associated benefits, and drawbacks of the respective available conventional and molecular approaches, and potentially the whole genome sequencing (WGS) to be directed for future exploration.

Antimicrobial Susceptibility Trends of Streptococcus pneumoniae by Age Groups Over Recent 10 Years in a Single Hospital in South Korea

PURPOSE

Streptococcus pneumoniae (S. pneumoniae) causes respiratory tract infections. Its non-vaccine serotypes and multidrug-resistant pneumococcal diseases have increased during the post-pneumococcal vaccination era. Therefore, it is important to understand the regional and age-related antimicrobial susceptibility of S. pneumoniae to select appropriate empirical antimicrobials.

MATERIALS AND METHODS

We retrospectively studied trends in the antimicrobial resistance of S. pneumoniae to commonly prescribed antibiotics in patient groups of various ages at a single teaching hospital in Jeju Island from 2009 to 2018.

RESULTS

In total, 1460 S. pneumoniae isolates were obtained during the study period. The overall antimicrobial resistance rates of S. pneumoniae to penicillin, erythromycin, ceftriaxone, levofloxacin, and vancomycin were 16.2%, 84.7%, 25.9%, 3.3%, and 0.0%, respectively, and the MDR rate was 6.7%. Erythromycin and ceftriaxone resistance rates increased by years; however, they were significantly reduced in adult groups. Levofloxacin resistance and MDR rates were also higher in adult groups. Overall, the MDR rate significantly increased during the recent 10 years, as well as in patients with a history of hospitalization within 90 days [odds ratio (OR)=3.58, 95% confidence interval (CI)=1.91-6.71] and sinusitis (OR=4.98, 95% CI=2.07-11.96).

CONCLUSION

Erythromycin and ceftriaxone resistance rates and the MDR rate of S. pneumoniae significantly increased during the recent 10 years; the trends in individual antimicrobial resistance rates significantly differed between the age groups. This study indicates the need for caution when using ceftriaxone as an empirical antimicrobial against pneumococcal infections.

Burden of invasive pneumococcal disease (IPD) over a 10-year period in Bogotá, Colombia

BACKGROUND

Invasive pneumococcal disease (IPD) is the leading cause of infectious death worldwide. This study aimed to describe the epidemiology of IPD and the impact of pneumococcal conjugate vaccine-10 (PCV-10) over a 10-year period in Bogotá, Colombia.

METHODS

This was a laboratory-based surveillance study of Streptococcus pneumoniae isolated from patients with IPD from 82 hospitals over 10 years in Bogotá, Colombia. Data were compared between two periods: 2007-2011 (before the introduction of PCV-10) and 2012-2017 (after the introduction of PCV-10).

RESULTS

In total, 1670 patients with IPD were included in the study between 2007 and 2017. Between 2007 and 2011, the most common serotypes were 14, 1, 6B, 6A and 3. Between 2012 and 2017, the most common serotypes were 19A, 3, 14 and 1. A decrease in the incidence of IPD, particularly in children aged 0-4 years, was noted after the introduction of PCV-10. Importantly, this reduction in incidence was not observed in patients aged ≥50 years.

CONCLUSIONS

The IPD burden in Bogotá remained stable between 2007 and 2017. The incidence of IPD decreased in children but not in older adults. The introduction of PCV-10 led to a change in the most prevalent serotypes to serotypes that are not included in PCV-10.

Characterization of Escherichia coli isolates potentially covered by ExPEC4V and ExPEC10V, that were collected from post-transrectal ultrasound-guided prostate needle biopsy invasive urinary tract and bloodstream infections

There is an increasing incidence of infectious complications caused by extraintestinal pathogenic Escherichia coli (ExPEC) after transrectal ultrasound-guided prostate needle biopsy (TRUS-PNB), and a need for prophylaxis methods effective against associated antibiotic-resistant organisms. We aimed to identify the O-serotypes of ExPEC isolates collected in a sample of 60 patients with invasive ExPEC disease (IED) after TRUS-PNB, by serotype-specific agglutination and polymerase chain reaction (PCR) assays. The prevalence of O-serotypes included in a tetravalent ExPEC vaccine was 38.3% by agglutination and 46.7% by PCR, while the prevalence of O-serotypes included in a decavalent vaccine was 58.3% and 73.3%, respectively. Therefore, compared to the tetravalent vaccine, the decavalent vaccine would theoretically provide coverage for serotypes carried by a higher proportion of circulating ExPEC in patients undergoing TRUS-PNB, including a high proportion of antibiotic-resistant organisms.

Invasive Pneumococcal Disease Caused by Non-Vaccine Type Multidrug-Resistant Streptococcus pneumoniae Transmitted by Close Contact in a Healthy Adult

The incidence of vaccine-type Streptococcus pneumoniae carriage and disease have declined in vaccinated children as well as in unvaccinated children and adults. However, diseases caused by non-vaccine type (NVT) S. pneumoniae are increasing. In this study, we report an invasive pneumococcal disease (IPD) caused by NVT multidrug-resistant (MDR) S. pneumoniae transmitted from a vaccinated infant to an unvaccinated healthy woman, and the clinical characteristics of this serotype. A 29-year-old previously healthy woman visited our hospital with fever and headache. She had been breastfeeding her baby for 8 months. She was diagnosed with brain abscess and sinusitis caused by S. pneumoniae. Although the patient had no previous exposure to antibiotics, antibiotic susceptibility test identified the pathogen as MDR. The patient's family members were examined using nasopharyngeal swabs for bacterial culture. The serotype of S. pneumoniae identified from the blood, abscess, and sputum of the patient was 15B/C. After investing the patient's family members, we found that the serotype from nasopharyngeal specimen of her baby was the same. We described an invasive MDR pneumococcal disease in an immunocompetent young adult in the community. IPD likely spread to the patient by close contact with her baby, who harbored S. pneumoniae of NVT. The spread of NVT S. pneumoniae in the post-vaccine era has increased in the community, and resistance pattern for S. pneumoniae of 15B/C changed compared to the pre-pneumococcal conjugate vaccine era. The spread of MDR pathogens causing IPD among family members should be monitored.