Streptococcus pneumoniae serotype 19A in Latin America and the Caribbean: a systematic review and meta-analysis, 1990-2010

Streptococcus pneumoniae serotype 19A in hospitalized children with invasive pneumococcal disease after the introduction of conjugated vaccines in Lima, Peru

BACKGROUND

The Pneumococcal conjugate vaccine (PCV) has decreased cases of invasive pneumococcal disease (IPD) worldwide. However, the impact of PCVs introduction may be affected by the serotype distribution in a specific context.

METHODS

Cross-sectional multicenter passive surveillance study of IPD cases in pediatric patients hospitalized in Lima, Peru between 2016 and 2019 (after PCV13 introduction) to determine the serotype distribution and antimicrobial resistance of Streptococcus pneumoniae. Serotyping was performed by a sequential multiplex PCR and confirmed by whole genome sequencing.

RESULTS

Eighty-five S. pneumoniae isolates were recovered (4.07/100,000 among children <60 months of age). Serotype 19A was the most common (49.4%). Children infected with serotype 19A in comparison with children infected with other serotypes were younger, had a lower rate of meningitis and higher rates of pneumonia, complicated pneumonia and antimicrobial resistance; 28.6% of patients with serotype 19A have received at least one dose of PCV13 vs. 62.8% of patients with other serotypes. Using MIC-breakpoints, 81.2% (56/69) of non-meningitis strains and 31.2% (5/16) of meningitis strains were susceptible to penicillin; 18.8% (3/16) of meningitis strains had intermediate resistance to ceftriaxone. Resistance to azithromycin was 78.8% (67/85). Serotype 19A frequency increased over time in the same study population, from 4.2% (4/96) in 2006-2008, to 8.6% (5/58) in 2009-2011, to 49.4% (42/85) in the current study (2016-2019) (p < 0.001).

CONCLUSIONS

After PCV13 introduction in Peru, serotype 19A remains the most prevalent; however, the vaccination coverage is still not optimal. Therefore, additonal surveillance studies are needed to determine the remaining IPD burden.

Pneumococcal serotypes and antibiotic resistance in healthy carriage children after introduction of PCV13 in Lima, Peru

OBJECTIVE

To determinate the frequency of Streptococcus pneumoniae nasopharyngeal carriers, serotypes and antimicrobial resistance in healthy children in Lima, Peru, post-PCV13 introduction and to compare the results with a similar study conducted between 2006 and 2008 before PCV7 introduction (pre-PCV7).

METHODS

A cross-sectional multicenter study was conducted between January 2018 and August 2019 in 1000 healthy children under two years of age. We use standard microbiological methods to determinate S. pneumoniae from nasopharyngeal swab, Kirby Bauer and minimum inhibitory concentration methods to determinate antimicrobial susceptibility and whole genomic sequencing to determinate pneumococcal serotypes.

RESULTS

The pneumococcal carriage rate was 20.8 % vs. 31.1 % in pre-PCV7 (p < 0.001). The most frequent serotypes were 15C, 19A and 6C (12.4 %, 10.9 % and 10.9 % respectively). The carriage of PCV13 serotypes after PCV13 introduction decreased from 59.1 % (before PCV7 introduction) to 18.7 % (p < 0.001). Penicillin resistance was 75.5 %, TMP/SMX 75.5 % and azithromycin 50.0 %, using disk diffusion. Penicillin resistance rates using MIC breakpoint for meningitis (MIC ≥ 0.12) increased from 60.4 % to 74.5 % (p = 0.001).

CONCLUSION

The introduction of PCV13 in the immunization program in Peru has decreased the pneumococcal nasopharyngeal carriage and the frequency of PCV13 serotypes; however, there has been an increase in non-PCV13 serotypes and antimicrobial resistance.

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.

Emergence of Streptococcus pneumoniae serotype 19A (Spn19A) in the pediatric population in Bogotá, Colombia as the main cause of invasive pneumococcal disease after the introduction of PCV10

Introduction: With the use of pneumococcal conjugate vaccines(PCV), the behavior of invasive pneumococcal disease(IPD) has changed relative to serotype distribution. The introduction of these vaccines in national immunization programs has reduced the incidence of IPD, with a marked decrease in the circulation of the serotypes included in the vaccine used in each country. However, the subsequent emergence of other serotypes not included in the vaccine, such 19A in case of PCV7 and PCV10, has been documented. Materials and methods: This was case series study (2008-2017) in pediatric patients admitted to 10 hospitals in Bogota who were diagnosed with IPD. It was conducted during the transitional period of implementing the PCV10 vaccine in Colombia in 2012. Cases of bacteremic pneumococcal pneumonia, meningitis, primary bacteremia and osteoarticular infection were included. A descriptive analysis of the demographic, clinical and laboratory variables of patients with IPD by Spn19A, its trend over time, profiles of antimicrobial susceptibility and clinical outcomes was performed. Results: There were 463 cases of IPD, 315(68%) with known serotypes. The prevalence of IPD by Spn19A was 17.7%(56 cases), tending to increase over time. During 2008-2011, the prevalence was 4.4%, and during 2014-2017, it was 32.4%, The most frequent diagnosis was pneumonia(80.4%). In nonmeningeal isolates, 39.6% were not susceptible to penicillin. An increase in the resistance was observed over time. Conclusion: Spn19A is a prevalent cause of IPD in the pediatric population of the analyzed cohort, with an increasing trend of this serotype during the surveillance period after the introduction of PCV10, being the most common serotype identified in recent years.

Molecular characterization of Latin American invasive Streptococcus pneumoniae serotype 19A isolates

Streptococcus pneumoniae is a major cause of morbidity and mortality worldwide, especially among children and the elderly. S. pneumoniae serotype 19A has emerged as a major cause of invasive disease in many countries, regardless of whether pneumococcal conjugate vaccines are used. The aim of this study was molecular characterization of invasive S. pneumoniae serotype 19A isolates recovered between 2000 and 2015 from 13 National Laboratories through the laboratory-based surveillance of invasive S. pneumoniae program SIREVA II in Latin American countries. The isolates were submitted with antimicrobial susceptibility tests and were genotyped by a combination of pulsed field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Of the 185 isolates assayed, notable rates of resistance to penicillin (MIC ≥ 0.125 µg/mL; 68.6%), tetracycline (63.7%), trimethoprim-sulfamethoxazole (63.2%), and erythromycin (43.2%) were observed, while 44.3% of isolates were multidrug resistant. The most frequently observed sequence types (ST) were ST320 (32.4%), ST199 (14.1%), ST172 (10.8%) and ST5204 (7.1%). The distribution of STs indicated regional differences in the epidemiology of the clonal groups. The present study showed a diverse genetic background of the pneumococcal population in Latin American countries. Continuous surveillance of the pneumococcal serotype 19A population in the region will be necessary to obtain information about geographical differences and changes in the spread and the establishment of particular clones.

Emergence of serotype 19A Streptococcus pneumoniae after PCV10 associated with a ST320 in adult population, in Porto Alegre, Brazil

Use of pneumococcal conjugate vaccines has caused emergence of non-vaccine serotypes. No Brazilian data specifically about serotype 19A are available. We aimed to evaluate the frequency of occurrence, susceptibility profile and molecular epidemiology of serotype 19A before and after vaccine introduction in Brazil. Pneumococcal identification was performed by the conventional method. Strain serotype was determined by multiplex polymerase chain reaction (PCR) and/or Quellung reaction. Resistance was determined by Etest^® and PCR was performed to determine the presence of macrolide resistance genes, ermB and/or mefA. Pneumococci were typed by Multilocus Sequence Typing. Thirty-eight serotype 19A Streptococcus pneumoniae were recovered, mostly from invasive diseases. Prevalence of serotype 19A increased following vaccination (from 3.5% before vaccination to 8.1% after, p = 0.04196). Non-susceptibility increased to most antimicrobials after vaccine introduction and was associated with clonal complex (CC)320. MLST showed nine different STs, which were grouped in one main CC: CC320 (63.9%). During the post-vaccination era, the frequency of this serotype increased significantly from 1.2% in 2011 to 18.5% in 2014 (p = 0.00001), with a concomitant decrease in the genetic variability: ST320 consistently predominated after vaccine-introduction (61.1%). Overall, our results showed a post-PCV10 increase in the frequency of serotype 19A. This was accompanied by a selection of CC320 and antimicrobial resistance.

Modeling the sustained use of the 13-valent pneumococcal conjugate vaccine compared to switching to the 10-valent vaccine in Mexico

Introduction: Pneumococcal diseases caused by Streptococcus pneumoniae represent a significant health and economic burden. Mexico has benefited from the inclusion of the 7-valent (PCV7) and 13-valent pneumococcal conjugate vaccines (PCV13) since their inclusion in the National Immunization Program (NIP) in 2006 and 2010, respectively. The objective of this study is to estimate the impact of the existing program and predict future implications of a change in the current program.

Methods: A previously published model was updated to estimate the historic impact of the PCV programs relative to pre-PCV implementation. Future disease trends were forecasted based on historical serotype behaviors for each PCV13 serotype and non-vaccine serotypes across different age groups. Costs and outcomes were estimated over a 10-year period based on continued use of PCV13 compared to a switch to PCV10.

Results: The PCV7 and subsequent PCV13 NIP were estimated to prevent over 1.5 million cases of pneumococcal disease and 1,854 deaths, corresponding to a net savings of $34.50 Billion MXN. Continued use of PCV13 was estimated to save over 300 thousand cases of pneumococcal disease and 373 deaths compared to switching to PCV10 over a 10-year period. Despite a higher vaccine cost, maintaining PCV13 was cost-saving compared to PCV10, saving $6.71 billion MXN over 10 years.

Conclusion: The PCV program in Mexico has provided a significant return on investment. Sustained PCV13 use was estimated to provide the greatest healthcare and economic impact in Mexico. Changes to the pneumococcal vaccination program could result in serotype replacement and reduction in herd effects.

Genetic profiles and antimicrobial resistance of Streptococcus pneumoniae non-PCV10 serotype isolates recovered from meningitis cases in Salvador, Brazil

In 2010, the 10-valent pneumococcal conjugate vaccine (PCV10) was introduced into the Brazilian childhood vaccination programme. Concerns have been raised that non-vaccine serotypes could increase in prevalence and reduce the benefits of vaccination; therefore, we examined non-PCV10 isolates recovered from meningitis during pre- (January 2008-May 2010) and post-vaccine (June 2010-December 2012) periods. Surveillance for pneumococcal meningitis was established at the Reference Hospital of Infectious Diseases in Salvador, Brazil. Serotypes were determined by multiplex PCR and/or Quellung reaction. Antimicrobial susceptibility testing was conducted by E-test and broth microdilution. Genotyping used PFGE and multi-locus sequence typing. A total of 148 cases of meningitis were identified from January 2008 to December 2012, 77 (52 %) of which were due to non-PCV10 isolates, with 50 (52.1 %) from pre-vaccine and 27 (52 %) from post-vaccine periods. In the post-vaccine period, the non-PCV10 serotypes 12F (n=6; 22.2 %), 10A (n=3; 11.1 %), 15B (n=2; 7.4 %) and 18B (n=2; 7.4 %) were the most prevalent. Forty-three isolates (55.8 %) were non-susceptible to one or more antibiotics. Non-susceptibility to penicillin was observed among serotypes 19A (three isolates), 9N (one isolate) and 12F (one isolate). PFGE and multi-locus sequence typing results demonstrated a wide genetic diversity among the isolates. During the early period following PCV10 introduction, no obvious emergence of a particular serotype was evident among non-PCV10 strains. This study underscores the importance of monitoring any changes among non-PCV10 cases after the introduction of PCV10.

Serotypes and genotypes of Streptococcus pneumoniae isolates from Trinidad and Tobago

OBJECTIVES

There are currently 94 known pneumococcal capsular polysaccharide serotypes and their prevalence differs by geographic region and the period studied. Streptococcus pneumoniae infections have been diagnosed clinically in Trinidad and Tobago and other Caribbean countries, however data on the serotype and sequence type distributions in this country are limited. The objective of this study was to determine serotypes and multilocus sequence types (MLSTs) of invasive and non-invasive pneumococcal isolates from Trinidad and Tobago.

METHODS

Ninety-eight pneumococcal isolates from several regional hospitals in the country were analyzed using both standard microbiological methods and molecular analysis. These isolates included invasive (n=83) and selected non-invasive (n=15) strains recovered before (n=25) and after (n=73) the introduction of the pneumococcal conjugate vaccine.

RESULTS

More than half of the isolates (54.1%) were recovered from children under 15 years of age, with the largest proportion being from children under 2 years of age (24.5%). The most prevalent serotypes were 19F (18.4%), 6B (15.3%), 23F (14.3%), 3 (11.2%), 19A (6.1%), 6A (5.1%), 14 (5.1%), and 9V (4.1%). The most common serotype/MLST combinations were 6B/ST138 (n=10, 10.2%), 3/ST180 (n=5, 5.1%), 23F/ST629 (n=5, 5.1%), 19F/ST8398 (n=4, 4.1%), and three each of 6B/ST145, 14/9V/ST156, 9V/ST162, 19A/320, and 3/ST10440.

CONCLUSIONS

This report provides the first glimpse of the prevailing pneumococcal sequence types in the country. Most of the isolates represented serotypes in the 10-valent (61.2% of isolates) and 13-valent (83.7%) pneumococcal conjugate vaccines. A detailed population study is warranted to fully determine the circulating pneumococcal sequence types. Furthermore, the implementation of an effective and continuous surveillance system in Trinidad and Tobago is paramount to monitor vaccine impact.

Open-label trial of immunogenicity and safety of a 13-valent pneumococcal conjugate vaccine in adults ≥ 50 years of age in Mexico

This open-label multicenter clinical trial conducted in Mexico assessed the immunogenicity and safety of a 13-valent pneumococcal conjugate vaccine (PCV13) in adults ≥ 50 years of age not previously vaccinated with the 23-valent pneumococcal polysaccharide vaccine (PPSV23). The PCV13 elicited a robust immune response in this study population, as reflected by the magnitude of fold rises in functional antibody levels measured by serotype-specific opsonophagocytic activity (OPA) assays before and 1 month after vaccination. Although the prevaccination OPA geometric mean titers (GMTs) for the majority of the serotypes were significantly lower in the 50- to 64-year age group than those in the ≥ 65-year age group, the postvaccination immune responses were generally similar. The overall immune responses were higher for the majority of the serotypes in the Mexican study population than those in similar adult study populations who received the PCV13 in Europe and the United States. PCV13 was well tolerated, and there were no vaccine-related serious adverse events. In conclusion, PCV13 is safe and immunogenic when administered to adults ≥ 50 years of age in Mexico and has the potential to protect against vaccine-type pneumococcal disease. (This study has been registered at ClinicalTrials.gov under registration no. NCT01432262.).

Bacteremic pneumococcal pneumonia: serotype distribution, antimicrobial susceptibility, severity scores, risk factors, and mortality in a single center in Chile

AIMS

Bacteremic pneumococcal pneumonia (BPP) is a severe condition. To evaluate seasonal distribution, mortality, serotype frequencies, antimicrobial susceptibility, and different severity scores among patients with BPP.

PATIENTS AND METHODS

Patients were identified by laboratory data and restricted to adulthood. Standard methods were used for serotyping and antimicrobial susceptibility. Risk factors were analyzed by univariate and multivariate methods. Severity scores (APACHE II, CURB-65 and CAP PIRO) were compared using ROC curves.

RESULTS

Sixty events of community-acquired BPP occurred between 2005 and 2010. A seasonal pattern was detected. Mean age was 72.1 years old (81.4% ≥ 60 years). All had a predisposing factor. Previous influenza (3.3%) or pneumococcal immunization (1.7%) was infrequent. Admission to critical units was required by 51.7%. Twenty-two serotypes were identified among 59 strains. Only one strain had intermediate resistance to penicillin (1.7%). In-hospital mortality reached 33.3%. Multivariate analysis identified a CAP PIRO score>3 (OR 29.7; IC95 4.7-187), age ≥ 65 years (OR 42.1; IC95 2.2-796), and a platelet count<100,000/μL (OR 10.9; IC95 1.2-96) as significant independent factors associated with death. ROC curve analysis did not reveal statistical differences between the three severity scores to predict death (AUC 0.77-0.90). The prognostic yield for all of them was limited (Positive Likelihood Ratio: 1.5-3.8).

CONCLUSIONS

BPP had a high case-fatality rate in this group of adult patients with no association to resistant isolates, and a low immunization record. Three independent factors were related to death and the prognostic yield of different severity scores was low.

Serotype and genotype distribution among invasive Streptococcus pneumoniae isolates in Colombia, 2005-2010

In Colombia, a laboratory-based surveillance of invasive Streptococcus pneumoniae isolates as part of SIREVA II PAHO has been conducted since 1994. This study describes the serotype distribution, antimicrobial resistance, and genetic relationships of pneumococcal isolates recovered in Colombia from 2005 to 2010. In this study, demographic data of invasive S. pneumoniae isolates were analyzed, and antimicrobial susceptibility patterns were determined. Pulse field gel electrophoresis (n = 629) and multilocus sequence typing (n = 10) were used to determine genetic relationship of isolates with minimal inhibitory concentration to penicillin ≥0.125 µg/mL. A total of 1775 isolates of S. pneumoniae were obtained. Fifteen serotypes accounted for 80.7% of isolates. Serotype 14 (23.1%) was the most frequent in the general population. Penicillin resistance was 30.7% in meningitis and 9.0% in non-meningitis. Clones Spain^6BST90, Spain^9VST156, Spain^23FST81, and Colombia^23FST338 were associated to isolates. Additionally, serotype 6A isolates were associated with ST460 and ST473, and 19A isolates with ST276, ST320, and ST1118. In conclusion, the surveillance program provided updated information of trends in serotype distribution, antimicrobial resistance and the circulation of clones in invasive pneumococcal diseases. These results could be helpful to understand the epidemiology of S. pneumoniae in Colombia, and provide a baseline to measure the impact of vaccine introduction.