Serotype Distribution and Multi Locus Sequence Type (MLST) of Erythromycin-Resistant Streptococcus Pneumoniae Isolates in Tehran, Iran

Background

The number of erythromycin-resistant Streptococcus pneumoniae has significantly increased around the world. The present study aimed to determine the serotype distribution and molecular epidemiology of the erythromycin-resistant Streptococcus pneumoniae (ERSP) isolated from patients with invasive disease.

Methods

A total of 44 Streptococcus pneumoniae isolates were tested for susceptibility to several antimicrobial agents. Additionally, the polymerase chain reaction (PCR) was applied to evaluate ERSP isolates in terms of the presence of erythromycin resistance genes (e.g., ermB and mefA). The isolates were serotyped using the sequential multiplex-PCR method, and molecular epidemiology was assessed through the multilocus sequence typing (MLST) analysis.

Results

The results represented multidrug resistance (MDR) in approximately half of the pneumococcal isolates. Among 22 ERSP isolates, 20 (90.9%) and 12 (56%) ones contained ermB and mefA, respectively. Further, 14 (31.8%), 3 (22.7%), and 19A (18.1%) were the common serotypes among the isolates. No significant correlation was observed between serotypes and erythromycin resistance genes. Furthermore, the MLST results revealed 18 different sequence types (STs), the top ones of which were ST3130 (3 isolates) and ST166 (3 isolates). Population genetic analysis disclosed that CC63 (32%), CC156 (18%), and CC320 (18%) were identified as the predominant clonal complexes.

Conclusions

The ERSP isolates exhibited high genetic diversity. The large frequency of MDR isolates suggests the emergence of high resistant strains, as well as the need to implement vaccination in the immunization schedule of Iran. These accumulating evidences indicate that 13-valent pneumococcal conjugate vaccines provided higher serotype coverage in the ERSP isolates.

Impact of 10-valent Pneumococcal Conjugate Vaccine (PCV10) on nasopharyngeal carriage in children 2 years of age: Data from a four-year time series cross-sectional study from Pakistan

The dataset described in this paper was collected for a time-series cross-sectional study exploring the impact of 10-valent Pneumococcal Conjugate Vaccine (PCV10) on nasopharyngeal (NP) carriage in children under 2 years of age from a rural population in Sindh, Pakistan. The study was carried out in two union councils of Matiari - Khyber and Shah Alam Shah Jee Wasi (Latitude 25.680298 / Longitude 68.502711). Data was collected on socio-demographics, clinical characteristics and vaccination status using android phone-based application. NP samples were collected using standard World Health Organisation (WHO) techniques, culture and serotyping was done using sequential Multiplex PCR described by Centre for Disease Control, USA. We looked at the carriage rate of vaccine type (VT) and non-vaccine type (NVT) serotypes over time in vaccinated and unvaccinated children. We additionally looked at the predictors for pneumococcal carriage. The uploaded dataset, available on Mendeley data repository (Nisar, Muhammad Imran (2021), “Impact of PCV10 on nasopharyngeal carriage in children in Pakistan”, Mendeley Data, V1, doi:10.17632/t79h6g97gr.1), has 3140 observations in CSV format. Additional files uploaded include a data dictionary and the set of questionnaires. The dataset and accompanying files can be used by other interested researchers to replicate our analysis, carry similar analysis under varying set of assumptions or perform additional exploratory or metanalysis

Validation of a Multiplexed Opsonophagocytic Assay for 11 Additional Pneumococcal Serotypes and Its Application to Functional Antibody Evaluation Induced by Pneumococcal Polysaccharide Vaccine

BACKGROUND

Various pneumococcal vaccines have been evaluated for immunogenicity by opsonophagocytic assay (OPA). A multiplexed OPA (MOPA) for 13 pneumococcal serotypes was developed by Nahm and Burton, and expanded to 26 serotypes in 2012. The development of new conjugate vaccines with increased valence has necessitated expanded MOPAs to include these additional serotypes. In this study, we validated this expanded MOPA platform and applied to measure antibodies against 11 additional serotypes (2, 8, 9N, 10A, 11A, 12F, 15B, 17F, 20B, 22F, and 33F) in human sera.

METHODS

All materials, including serum, complement, bacterial master stocks, and HL-60 cells, were evaluated for assay optimization. Following optimization, the assay was validated for accuracy, specificity, and intra- and inter-assay precision with sera from adult donors following standard protocols. The assay was applied to evaluate functional antibodies of 42 sera immunized with 23-valent pneumococcal polysaccharide vaccine (PPV23).

RESULTS

The expanded MOPA platform was specific for all serotypes, with the exception of serotype 20. The assay results were highly correlated with those obtained from single-serotype OPA, indicating acceptable accuracy. The coefficients of variation were 7%-24% and 13%-39% in tests of intra- and inter-assay precision, respectively, using three quality-control samples. A MOPA that included 11 additional serotypes in the PPV23 was established and validated with respect to accuracy, specificity, and precision. The opsonic indices of immune sera were obtained using this validated assay.

CONCLUSION

The expanded MOPA will be useful for evaluation of the immunogenicity of PPV23 and future conjugate vaccine formulations.

Primary Care Physicians' Struggle with Current Adult Pneumococcal Vaccine Recommendations

INTRODUCTION

In 2012, the Advisory Committee on Immunization Practices recommended 13-valent pneumococcal conjugate vaccine (PCV13) in series with 23-valent pneumococcal polysaccharide vaccine (PPSV23) for at-risk adults ≥19; in 2014, it expanded this recommendation to adults ≥65. Primary care physicians' practice, knowledge, attitudes, and beliefs regarding these recommendations are unknown.

METHODS

Primary care physicians throughout the U.S. were surveyed by E-mail and post from December 2015 to January 2016.

RESULTS

Response rate was 66% (617 of 935). Over 95% of respondents reported routinely assessing adults' vaccination status and recommending both vaccines. A majority found the current recommendations to be clear (50% "very clear," 38% "somewhat clear"). Twenty percent found the upfront cost of purchasing PCV13, lack of insurance coverage, inadequate reimbursement, and difficulty determining vaccination history to be "major barriers" to giving these vaccines. Knowledge of recommendations varied, with 83% identifying the PCV13 recommendation for adults ≥65 and only 21% identifying the recommended interval between PCV13 and PPSV23 in an individual <65 at increased risk.

CONCLUSIONS

Almost all surveyed physicians reported recommending both pneumococcal vaccines, but a disconnect seems to exist between perceived clarity and knowledge of the recommendations. Optimal implementation of these recommendations will require addressing knowledge gaps and reported barriers.

[Paediatric Invasive Pneumococcal Disease Before Universal Vaccination: 1995 - 2015]

INTRODUCTION

Pneumococcal conjugate vaccine was introduced in the private market in Portugal in 2001, reaching over the years a moderately high coverage. In July 2015, it was included in the National Immunisation Program. The aim of this study was to characterize invasive pneumococcal disease in a pediatric hospital before universal use of the vaccine.

MATERIAL AND METHODS

Retrospective analysis of medical records of all children with Streptococcus pneumoniae identified by culture and/or molecular biology (available since 2008), in products obtained from sterile sites, from January 1995 to June 2015. We evaluated demographic, clinical and microbiological data. Serotype results are available since 2004.

RESULTS

Over those 20 years, 112 invasive pneumococcal disease cases were identified, with a median age of 15 months (1 month - 15 years). The median number of cases /year was 4, the highest between 2001 - 2002 (8/year) and 2007 - 2012 (7 - 11/year). The identification occurred mostly in blood culture (72), cerebrospinal fluid (24), pleural fluid (11) an others (5). The most frequent diagnoses were pneumonia (38%), occult bacteraemia (34%) and meningitis (21%). Over the period under review, there was an increase of pneumonia and slight increase of OB, with meningitis cases remaining relatively unchanged.

DISCUSSION

In the last two decades, there was no reduction in the number of cases of invasive pneumococcal disease. There was an increase in isolates from pneumonia and occult bacteraemia that might be due to the introduction of molecular biological methods for Streptococcus pneumoniae detection. Vaccine serotypes were predominant.

CONCLUSION

This retrospective analysis before universal vaccination will contribute to evaluate the impact of vaccination in the Portuguese pediatric population.

[Estimates of Target Population for Pneumococcal Vaccination in People over 50 years in Catalonia and Spain]

OBJECTIVE

Published data about prevalence of distinct risk condictions for pneumococcal disease is scarce. This study investigated the prevalence of distinct risk conditions for pneumococal disease in Catalonian adults and stimated the potential size of target population for pneumococcal vaccination in Catalonia and Spain.

METHODS

Cross-sectional population-based study that included 2,033,465 individuals older than 49 years-old assigned to the Catalonian Health Institute (Catalonia, Spain) at 01/01/2015. The Catalonian Health Institute Information System for the Development of Research in Primary Care (SIDIAP) was used to identify comorbidities and/or underlying conditions in each subject and establish potential target population for pneumococcal vaccination on the basis of their risk for suffering pneumococcal infections: 1) immunocompromised subjects; 2) immunocompetents subjects with any risk condition; 3) immunocompetents subjects without risk conditions.

RESULTS

Of the 2,033,465 study subjects, 1,053,155 (51.8%) had no risk conditions, 649,014 (31.9%) had one risk condition and 331,296 (16.3%) had multiple risk conditions (11.4% in 50-64 years vs 21.2% in people older than 65 years, p smaller than 0.001; 21.8% in men vs 11.6% in women, p smaller than 0.001). Overall, 176,600 (8.7%) and 803,710 (39.5%) were classified in risk stratum 1 and 2, respectively. According to distinct risk strata considered, the target population for pneumococcal vaccination varied between 0.2-1.9 million in Catalonia and 1.5-2.3 million in Spain.

CONCLUSIONS

In our setting, almost fifty percent of people ≥50 years have at least one risk condition to suffert pneumococcal disease. Adult population susceptible for pneumococal vaccination largely varies depending on the risk stratum considered as targeted people for pneumococcal vaccination.

Early Changes in the Serotype Distribution of Invasive Pneumococcal Isolates from Children after the Introduction of Extended-valent Pneumococcal Conjugate Vaccines in Korea, 2011-2013

This study was performed to measure early changes in the serotype distribution of pneumococci isolated from children with invasive disease during the 3-year period following the introduction of 10- and 13-valent pneumococcal conjugate vaccines (PCVs) in Korea. From January 2011 to December 2013 at 25 hospitals located throughout Korea, pneumococci were isolated among children who had invasive pneumococcal disease (IPD). Serotypes were determined using the Quellung reaction, and the change in serotype distribution was analyzed. Seventy-five cases of IPD were included. Eighty percent of patients were aged 3-59 months, and 32% had a comorbidity that increased the risk of pneumococcal infection. The most common serotypes were 19A (32.0%), 10A (8.0%), and 15C (6.7%). The PCV7 serotypes (4, 6B, 9V, 14, 18C, 19F, 23F, and 6A) accounted for 14.7% of the total isolates and the PCV13 minus PCV7 types (1, 3, 5, 7F and 19A) accounted for 32.0% of the total isolates. Serotype 19A was the only serotype in the PCV13 minus PCV7 group. The proportion of serotype 19A showed decreasing tendency from 37.5% in 2011 to 22.2% in 2013 (P = 0.309), while the proportion of non-PCV13 types showed increasing tendency from 45.8% in 2011 to 72.2% in 2013 (P = 0.108). Shortly after the introduction of extended-valent PCVs in Korea, serotype 19A continued to be the most common serotype causing IPD in children. Subsequently, the proportion of 19A decreased, and non-vaccine serotypes emerged as an important cause of IPD. The impact of extended-valent vaccines must be continuously monitored.

A Multicomponent Intervention to Improve Pneumococcal Vaccination Knowledge Among Internal Medicine Residents

INTRODUCTION

The Advisory Committee on Immunization Practices updated its pneumococcal vaccination guidelines in September 2014 and provided an additional recommendation in February 2016. We perceived a knowledge gap related to these guidelines among residents who serve as primary care physicians during postgraduate training. Our research team confirmed the presence of this knowledge gap and designed a curriculum focused on the current guidelines for pneumococcal vaccination.

METHODS

This curriculum consists of a preeducation quiz and survey, as well as an educational video, pocket card, and poster. The educational materials were then disseminated over a 7-week period and included a short video, handouts (laminated pocket cards), and summaries of guideline recommendations in electronic format.

RESULTS

The quiz, which includes eight clinical vignette selected-response items, revealed a knowledge deficiency. For example, only a minority of residents (31.2%) correctly chose the appropriate pneumococcal vaccination schedule for an elderly patient with multiple comorbid and chronic medical ailments. A postintervention survey showed that a majority of residents (87.5%) found the educational tools effective in improving understanding and implementation of vaccine guidelines.

DISCUSSION

This novel educational strategy is designed to increase resident knowledge of pneumococcal vaccination guidelines with eventual translation to actual clinical practice.

Serotype Distribution and Antimicrobial Susceptibilities of Invasive Streptococcus pneumoniae Isolates from Adults in Korea from 1997 to 2012

In Republic of Korea, a 7-valent pneumococcal conjugated vaccine (PCV7) was licensed for use in infants in 2003, and 13-valent PCV (PCV13) replaced it since 2010. We investigated trends in serotype distribution and antibiotic susceptibility of pneumococcal isolates from adult patients with invasive pneumococcal diseases (IPD). Invasive pneumococcal isolates from adult patients of ≥ 16 years of age were collected from 1997 to 2012. Serotypes of the isolates were determined by the Quellung reaction. Distribution of serotypes was analyzed according to the vaccine types. Antibiotic susceptibility was tested by using E-test strips. A total of 272 invasive pneumococcal isolates were included. The most common serotypes were serotype 19F (8.5%, 23/272), and serotype 3 (8.1%, 22/272), and 24.6% (67/272) of the isolates were of non-vaccine serotypes. Of the 272 isolates, 2.6% (7/272) were penicillin MICs of ≥ 4 µg/mL. The proportion of the PCV13 serotypes decreased from 63.3% (50/79) in 1997-2003 to 48.6% (17/35) in 2011-2012, whereas that of non-vaccine serotypes was 26.6% (21/79) and 25.7% (9/35), respectively, for the same periods. The proportion of the PCV13 serotypes showed a decreasing trend among adult patients with IPD over the study period.

Epidemiological burden of invasive pneumococcal disease in children and adolescents with predisposing risk factors

OBJECTIVE

Some medical conditions constitute important risk factors for the development of invasive pneumococcal diseases in children and adolescents aged from 5 to 19 years. Conjugate vaccines have potential efficacy in this scenario, but are not available in many Latin American public healthcare systems for this age group. This study aimed to estimate the preventable fraction of invasive pneumococcal diseases among individuals aged from 5 to 19 years with associated risk factors for its development.

METHODS

Data regarding the Latin America population, risk factors prevalence and conjugate vaccines efficacy were obtained from the literature.

RESULTS

Total population at risk ranged from 17.3 to 64.6 million of individuals and asthma was the most impacting risk factor. According to SIREVA, PCV13 provided a 62.9% serotypes coverage in individuals from 5 to 29 years in 2012, potentially increasing the covered population from [8,338,457-31,057,620] with PCV10 to [10,906,356-40,622,078] with PCV13. To date, according to available efficacy data, the hypothetically immunized population ranged from 11.4 to 42.4 million, representing 7.0% to 26.0% of the total population in this age group.

CONCLUSIONS

Vaccination in risk groups should be encouraged, as it potentially contributes to the reduction in the number of cases of invasive pneumococcal disease.

Changes in serotype distribution and antibiotic resistance of nasopharyngeal isolates of Streptococcus pneumoniae from children in Korea, after optional use of the 7-valent conjugate vaccine

We investigated serotype distribution and antimicrobial resistance of pneumococcal carriage isolates from children after optional immunization with the 7-valent pneumococcal conjugate vaccine (PCV7) in Korea. From June 2009 to June 2010, 205 (16.5%) pneumococcal isolates were obtained from 1,243 nasopharyngeal aspirates of infants and children at Seoul National University Children's Hospital, Korea. Serotype was determined by Quellung reaction and antibiotic susceptibility was tested by E-test. The results were compared to previous studies done in the pre-PCV7 period. In this study, the most common serotypes were 6A (15.3%), 19A (14.7%), 19F (10.2%), 35B (7.3%), and 6D (5.6%). The proportion of PCV7 serotypes decreased from 61.9% to 23.8% (P < 0.001). The overall penicillin nonsusceptibility rate increased from 83.5% to 95.4% (P = 0.001). This study demonstrates the impact of optional PCV7 vaccination in Korea; the proportion of all PCV7 serotypes except 19F decreased while antimicrobial resistant serotypes 6A and 19A further increased.