Dominance of multidrug-resistant Denmark(14)-32 (ST230) clone among Streptococcus pneumoniae serotype 19A isolates causing pneumococcal disease in Bulgaria from 1992 to 2013

Serotype distribution and antimicrobial resistance of pediatric Streptococcus pneumoniae isolated from inpatients and outpatients at Beijing Children's Hospital

BACKGROUND

Understanding the epidemiology of Streptococcus pneumoniae (S. pneumoniae) isolates is important for pneumonia treatment and prevention. This research aimed to explore the epidemiological characteristics of S. pneumoniae isolated from pediatric inpatients and outpatients during the same period.

METHODS

S. pneumoniae were isolated from unsterile samples of inpatients and outpatients younger than five years old between March 2013 and February 2014. The serotypes were determined using diagnostic pneumococcal antisera. The resistance of each strain to 13 antibiotics was tested using either the E-test or the disc diffusion method. The Sequence Types (STs) were analyzed via Multilocus Sequence Typing (MLST).

RESULTS

The dominant serotypes obtained from inpatients were 19F (32.9 %), 19A (20.7 %), 23F (10.7 %), 6A (10.0 %), and 14 (8.6 %), while those from outpatients were 19F (13.6 %), 23F (12.9 %), 6A (10.0 %), 6B (10.0 %), and 19A (7.9 %). The coverage rates of 13-valent Pneumococcal Conjugate Vaccine (PCV) formulations were high in both groups. The nonsusceptibility to penicillin, cefuroxime, imipenem, erythromycin, and trimethoprim-sulfamethoxazole among the inpatient isolates was 7.1 %, 92.8 %, 65.7 %, 100 %, and 85.0 %, respectively, while that among the outpatient isolates was 0.7 %, 50.0 %, 38.6 %, 96.4 %, and 65.7 %, respectively. There were 45 and 81 STs detected from the pneumococci isolated from inpatients and outpatients, respectively. CC271 was common among both inpatients and outpatients (43.6 % and 14.3 %).

CONCLUSIONS

Pneumococcal vaccine-related serotypes are prevalent among both inpatients and outpatients, especially among inpatients, who exhibit more severe antibiotic resistance. Therefore, universal immunization with PCV13 would decrease the hospitalization rate due to S. pneumoniae and the antibiotic resistance rate of S. pneumoniae.

Emergence of a multidrug-resistant and virulent Streptococcus pneumoniae lineage mediates serotype replacement after PCV13: an international whole-genome sequencing study

BACKGROUND

Serotype 24F is one of the emerging pneumococcal serotypes after the introduction of pneumococcal conjugate vaccine (PCV). We aimed to identify lineages driving the increase of serotype 24F in France and place these findings into a global context.

METHODS

Whole-genome sequencing was performed on a collection of serotype 24F pneumococci from asymptomatic colonisation (n=229) and invasive disease (n=190) isolates among individuals younger than 18 years in France, from 2003 to 2018. To provide a global context, we included an additional collection of 24F isolates in the Global Pneumococcal Sequencing (GPS) project database for analysis. A Global Pneumococcal Sequence Cluster (GPSC) and a clonal complex (CC) were assigned to each genome. Phylogenetic, evolutionary, and spatiotemporal analysis were conducted using the same 24F collection and supplemented with a global collection of genomes belonging to the lineage of interest from the GPS project database (n=25 590).

FINDINGS

Serotype 24F was identified in numerous countries mainly due to the clonal spread of three lineages: GPSC10 (CC230), GPSC16 (CC156), and GPSC206 (CC7701). GPSC10 was the only multidrug-resistant lineage. GPSC10 drove the increase in 24F in France and had high invasive disease potential. The international dataset of GPSC10 (n=888) revealed that this lineage expressed 16 other serotypes, with only six included in 13-valent PCV (PCV13). All serotype 24F isolates were clustered in a single clade within the GPSC10 phylogeny and long-range transmissions were detected from Europe to other continents. Spatiotemporal analysis showed GPSC10-24F took 3-5 years to spread across France and a rapid change of serotype composition from PCV13 serotype 19A to 24F during the introduction of PCV13 was observed in neighbouring country Spain.

INTERPRETATION

Our work reveals that GPSC10 alone is a challenge for serotype-based vaccine strategy. More systematic investigation to identify lineages like GPSC10 will better inform and improve next-generation preventive strategies against pneumococcal diseases.

FUNDING

Bill & Melinda Gates Foundation, Wellcome Sanger Institute, and the US Centers for Disease Control and Prevention.

Antimicrobial Resistance in Pneumococcal Carriage Isolates from Children under 2 Years of Age in Rural Pakistan

Antimicrobial resistance is an emerging public health concern. Ten-valent pneumococcal vaccine (PCV10) was introduced in Pakistan’s Expanded Program on Immunization (EPI) in 2012 as a 3 + 0 schedule without catchup. From 2014 to 2018, children <2 years were randomly selected in two rural union councils of Matiari, Pakistan. Nasopharyngeal swabs were collected using standard WHO guidelines by trained staff and processed at Infectious Disease Research Laboratory at The Aga Khan University, Karachi using culture on sheep blood agar and Multiplex PCR methods described by CDC, USA. Pneumococcal isolates were identified by optochin sensitivity and bile solubility tests. Isolates were then tested for antimicrobial susceptibility by standard Kirby-Bauer disk-diffusion method on Mueller-Hinton Agar (MHA) with 5% sheep blood agar as per Clinical & Laboratory Standards Institute (CLSI) recommendations. Of 3140 children enrolled, pneumococcal isolates were detected in 2370 (75%). Vaccine coverage improved from 41% to 68.4%. Out of the 2370 isolates, 88.4%, 37.6% and 25% were resistant to cotrimoxazole, tetracycline and erythromycin, respectively. There was no resistance to penicillin, ceftriaxone, and vancomycin. For erythromycin, resistance increased from 20% in 2014/15 to 30.8% in 2017/18 and for tetracycline it increased from 34.9% to 41.8% both of which were explained by an increase in prevalence of serotype 19A. Pneumococcal isolates were susceptible to penicillin, ceftriaxone, and vancomycin. They were largely resistant to cotrimoxazole and tetracycline. There was an increase in erythromycin and tetracycline resistance attributed to increasing prevalence of serotype 19A. Pneumococcal isolates from carriage and invasive disease should be closely monitored for antimicrobial susceptibility.

IMPORTANCE Antimicrobial resistance is an emerging public health concern particularly in low- and middle-income countries where there is poor regulation and easy availability of antibiotics. This is the first study from Pakistan to report antimicrobial resistance patterns of pneumococcus after vaccine introduction in the community. Pakistan was the first South-Asian country to introduce PCV10 in its Expanded Program on Immunization (EPI) in 2012 as a 3 + 0 schedule without catchup. In this study, we describe the PCV10 impact on antimicrobial resistance patterns of pneumococcal nasopharyngeal carriage in children younger than 2 years of age in a rural district in Pakistan after the introduction of the vaccine.

Phenotypic and genotypic characteristics of non-invasive S. pneumoniae isolates recovered from PCV10-vaccinated children in Bulgaria

PURPOSE

The non-invasive pneumococcal disease (NIPD) is a common infection during childhood. We aimed to define the clonal spread of pediatric non-invasive isolates recovered during the PCV10-period in Bulgaria concerning the serotype and antimicrobial susceptibility.

MATERIALS AND METHODS

Serogrouping/serotyping were performed using latex agglutination and capsular swelling reaction. Serogroup 6 strains were subjected to serotype-specific PCR's. The antibiotic susceptibilities were assessed by broth microdilution. MLST was performed to define the clonal composition.

RESULTS

We analyzed 154 pediatrics non-invasive S. pneumoniae isolates. The PCV10-vaccinated children were 94.1%. We disclosed 88% non-vaccine serotypes (NVTs) and 12% PCV10 - serotypes. All common serotypes among PCV10-vaccinated children (n ​= ​145) were non-vaccine types (NVTs): 19A (13.8%), 6C (11.7%), 3 (9.6%), 15A (8.3%) and 23A (5.5%). Antimicrobial non-susceptibility showed highest levels in erythromycin (50.0%), oral penicillin (49.4%), clindamycin (45.4%), trimethoprim-sulfamethoxazole (43.5%), tetracycline (42.2%), and ceftriaxone (14.3%). The multidrug-resistant strains (MDR) were 51.3%. MDR-serotypes were 6C (20.2%), 19A (17.7%), 15A (11.4%), 19F (10.1%), and 23A (8.9%). MLST presented 17 clonal complexes (CCs) with prevalence of CC320, CC386, CC505, CC8029 and CC2613 clustered 83% MDR isolates.

CONCLUSIONS

All emergent pediatric non-invasive serotypes in our geographic area during the studied PCV10-period were NVTs (19A, 6C, 3, 15A, and 23A). The fifth widespread CCs: CC320, CC386, CC505, CC8029 and CC2613 clustered 83% MDR isolates. Future surveillance of vaccine-induced changes in the clonality and the antimicrobial resistance of the pneumococcal population is needed.

Clonal distribution, antimicrobial resistance, and pilus islets in S.pneumoniae isolates recovered from PCV10-vaccinated children with suppurative AOM in Bulgaria (2015-2020), BULGARIA

Streptococcus pneumoniae is still a leading bacterial pathogen of acute otitis media (AOM), despite the available pneumococcal conjugate vaccines (PCVs). We conducted a study on the population structure, antibiotic nonsusceptibility, serotype distribution, and presence of pilus in middle ear fluids - S. pneumoniae isolates recovered from PCV10-vaccinated children with suppurative АОМ in Bulgaria. Non-susceptibility was revealed in 68.75% (n=33) of the isolates. Multidrug-resistance (MDR) has been detected in 60.4%. The dual macrolide resistance mechanism was predominant. Most widespread were non-PCV10 serotypes 3 (27.1%, n=13), 19A (25.0%, n=12), and VT 19F (23.0%, n=11). A total of 64.6% were non-PCV10-serotypes. Presence of Pilus type I was observed mostly in PCV10-serotypes. We disclosed a strong association between CCs, serotype, and antimicrobial resistance. The MLST revealed the presence of four CCs: CC320 (39.6%), CC505 (12.5%), CC1377 8.3%), and CC230 (8.3%), respectively. The most abundant CC320 comprised MDR 19A and 19F isolates. CC230 clustered MDR isolates from serotype 19A, 6C, and 14. CC505 and CC1377 covered serotype 3 susceptible isolates. The vaccine-induced changes and trends in antimicrobial resistance and clonality must be an object of systematic investigations.

A Laboratory-Based Surveillance Study of Invasive Neisseria meningitidis, Streptococcus pneumoniae, and Haemophilus influenzae Diseases in a Serbian Pediatric Population-Implications for Vaccination

The aim of this study was to present the epidemiology of invasive diseases caused by Neisseria meningitidis and Streptococcus pneumoniae in the pre-vaccine period, and Haemophilus influenzae in the post-vaccine period in a pediatric population from Serbia. Among the meningococci, serogroup B dominated (83%), followed by serogroup C (11.3%). High antigenic diversity was found, with fine type P1.5-1,10-4 being the most frequent. Moderate susceptibility to penicillin was common (55%). Within pneumococci, serotypes 19F, 14, 6B, 6A, 18C, 23F, 3, and 7F prevailed, while 19A was rare (3.6%). The coverages of PCV10 and PCV13 were 68% and 84%, respectively. Major sequence types were ST320, ST15, ST273, ST271, and ST81. Non-susceptibility to penicillin (66.7%), cefotaxime (37%), and macrolides (55%) was predominantly detected in vaccine-related serotypes. Among the 11 invasive H. influenzae isolates collected, there were six Hib, three non-type b, and two non-typeable strains (ntHi) that were antibiotic susceptible. These results imply a potential benefit of future Men-B vaccine implementations. For pneumococci, as PCV10 was recently introduced, a significant reduction of morbidity and antibiotic resistance might be expected. The efficiency of Hib vaccination is evident, but a shift towards non-type b and ntHi strains may be anticipated.

Clonal lineages and antimicrobial resistance of nonencapsulated Streptococcus pneumoniae in the post-pneumococcal conjugate vaccine era in Japan

OBJECTIVES

The emergence and spread of nonencapsulated Streptococcus pneumoniae (NESp) is a public health concern in the post-pneumococcal conjugate vaccine era. We analyzed the prevalence, molecular characteristics, and antimicrobial resistance of NESp responsible for noninvasive infections in northern Japan.

METHODS

NESp isolates were identified using molecular and phenotypical methods among 4463 S. pneumoniae isolates from noninvasive infection cases during 4 study periods between January 2011 and January 2019. NESp isolates were analyzed for antimicrobial susceptibility, genotype, and virulence-associated genes.

RESULTS

Seventy-one NESp isolates were identified (1.6% of total clinical isolates) and assigned to the null capsule clade (NCC)1 (pspK+) (94.4%) or NCC2 (aliC+/aliD+) (5.6%). The dominant sequence types (STs) were ST7502 (23.9%), ST4845 (19.7%), ST16214 (11.3%), ST11379 (9.9%), and ST7786 (7.0%). These 5 dominant STs and all 7 novel STs were related to the sporadic NESp lineage ST1106 or PMEN clone Denmark¹⁴-ST230. High non-susceptibility rates of NESp were observed for trimethoprim-sulfamethoxazole, erythromycin, and tetracycline (>92.9%), and multidrug resistance was observed in 88.7% of the NESp isolates, including all ST7502, ST4845, and ST11379 isolates.

CONCLUSIONS

The study revealed that the dominant clonal groups of NESp were associated with a high prevalence of non-susceptibility to antimicrobials in northern Japan.

First report on multidrug-resistant non-encapsulated Streptococcus pneumoniae isolated from a patient with pneumonia

The non-encapsulated Streptococcus pneumoniae (NESp) has emerged and increased in the clinical setting. The majority of NESp strains have been isolated from the nasopharynxes of healthy carriers and from respiratory specimens of patients with otitis media. NESp strains were shown to be more effective than encapsulated counterparts at forming biofilms. Therefore, NESp should become one of the leading causes of emerging refractory respiratory disease after the introduction of pneumococcal conjugate vaccines. We report the first case of multidrug-resistant - including fluoroquinolone-resistant - NESp isolated from the intrabronchial aspirate of a patient with pneumonia. Drug-resistant NESp infections can possibly emerge as a clinical problem and thus the continuous monitoring of NESp infections is of utmost importance.

Phenotypic and genotypic characterization of serogroup 6 Streptococcus pneumoniae isolates collected during 10-valent pneumococcal conjugate vaccine era in Bulgaria

Serogroup 6 remains common in the pneumococcal-conjugated vaccine era in Bulgaria; therefore, we investigated its clonal and serotype dynamics. The antibiotic susceptibilities were assessed by broth microdilution. Strains identified as serogroup 6 with latex agglutination method were subjected to serotype-specific PCRs. Erythromycin-resistant strains were analyzed by PCR for presence of ermB and mefE genes. MLST was performed to define clonal composition of the sequence types (STs). Serogroup 6 was represented by 40 (13.3%) from 301 invasive and non-invasive Streptococcus pneumoniae isolates. Molecular serotyping revealed new emerging serotype 6C (6.6%), not detected in pre-vaccine era. Among unvaccinated patients, mostly we observed serotypes 6А (57.1%) and 6В (28.6%). Serotype 6C was distinctive for vaccinated children (64%), followed by 6A (24%). Penicillin and ceftriaxone non-susceptible serogroup 6 strains were 65% and 5%, respectively; erythromycin- and clindamycin-resistant were 70.0% and 52.5%, respectively. Multidrug-resistant strains were 57.5%. Prevalent genetic determinant for macrolide resistance was ermB gene (75%). MLST revealed 17 STs into 5 clonal complexes and 7 singletons. Predominant genetic lineage was CC386, represented by MDR-6C non-invasive strains. Serotype 6B, principally responsible for invasive diseases in the pre-vaccine era, retreated this position to serotype 6A.

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.

Molecular characterization of predominant Streptococcus pneumoniae serotypes causing invasive infections in Canada: the SAVE study, 2011-15

Objectives

This study characterized the 11 most predominant serotypes of invasive Streptococcus pneumoniae infections collected by the annual SAVE study in Canada, between 2011 and 2015.

Methods

A subset of the 11 most predominant serotypes (7F, 19A, 22F, 3, 12F, 11A, 9N, 8, 33F, 15A and 6C) collected by the SAVE study was analysed using PFGE and MLST, as well as PCR to identify pilus-encoding genes. WGS analyses were performed on a subset of the above isolates plus a random selection of background strains.

Results

Of the predominant serotypes analysed, 7F, 33F and 19A were obtained more commonly from children <6 years of age, whereas 15A, 6C, 22F and 11A were more common in adults >65 years of age. Pneumococcal pilus PI-1 was identified in antimicrobial-susceptible serotype 15A (61/212) and <10% of 6C isolates (16/188). PI-2 was found in serotype 7F (683/701) and two-thirds of 11A isolates (162/241). Only serotype 19A-ST320 possessed both pili. Molecular and phylogenetic analyses identified serotypes 19A, 15A, 6C, 9N and 33F as highly diverse, whereas 7F, 22F and 11A demonstrated clonality. Antimicrobial resistance determinants were common within diverse serotypes, and usually similar within a clonal complex.

Conclusions

Despite successful use of conjugate vaccines, S. pneumoniae remains a highly diverse organism in Canada. Several predominant serotypes, both antimicrobial susceptible and MDR, have demonstrated rapid clonal expansion or an increase in diversity. As S. pneumoniae continues to evolve in Canada, WGS will be a necessary component in the ongoing surveillance of antimicrobial-resistant and expanding clones.

Characterization of macrolide-resistant non-invasive pneumococci in the pre-vaccine era in Serbia

Numerous reports have confirmed that increased macrolide use in the treatment of respiratory tract infection has contributed to the emergence of antibiotic resistance worldwide. Studies have also shown that pneumococcal vaccine can reduce pneumococcal resistance. The aim of this study was to determine the prevalence of co-resistance to penicillin and other antibiotics in macrolide-resistant (MR) non-invasive pneumococcal isolates and to evaluate serotype distribution in resistant strains in the pre-vaccine era in Serbia. About 80% of MR isolates expressed the MLS phenotype with very high resistance to both erythromycin and clindamycin. A total of 132 (84.1%) MR isolates were multiresistant, i.e., they were resistant to erythromycin, penicillin, tetracycline, and trimethoprim-sulfamethoxazole. Among 157 MR pneumococci, 11 different serotypes were found. Four serotypes, 19F, 14, 6B, and 23F, accounted for 77.7% of all MR pneumococcal isolates. Among isolates with the cMLS phenotype, serotypes 19F and 14 were predominant, whereas serotype 6A was the most common among those with the M phenotype, followed by 14. In conclusion, co-resistance to macrolides and penicillin in our non-invasive pneumococcal isolates is high. The majority of tested strains (∼80%) belonged to the four serotypes (19F, 14, 6B, and 23F) that are included in all conjugate vaccine formulations.

Rise of multidrug-resistant Streptococcus pneumoniae clones expressing non-vaccine serotypes among children following introduction of the 10-valent pneumococcal conjugate vaccine in Bulgaria

OBJECTIVES

Pneumococcal conjugate vaccines (PCVs) have reduced the incidence of pneumococcal disease, but non-vaccine serotypes are of concern, particularly if antimicrobial-resistant. This study retrospectively evaluated the serotype-specific clonality of paediatric multidrug-resistant (MDR) invasive and non-invasive Streptococcus pneumoniae isolates collected following PCV10 introduction (2011-2017) in Bulgaria.

METHODS

Capsular types, drug resistance patterns and multilocus sequence typing (MLST) of the most common MDR S. pneumoniae serotypes sampled from children were determined.

RESULTS

Overall, the rate of MDR pneumococci was 44.6% (107/240). The most common serotypes among MDR strains were 19F (25.2%), 19A (19.6%), 6C (13.1%), 6A and 23A (6.5% each) and 15A (4.7%), contributing 75.7% of all MDR strains. With the exception of serotype 19F, the remaining serotypes were non-PCV10 types. Among MDR pneumococci, the most frequently found sequence types were ST320 (30.4%; 19A and 19F), ST386 (12.7%; 6C and 6A) and ST8029 (5.1%; 23A). The majority of MDR STs (74.7%) belonged to PMEN clonal complexes, of which the most common were CC320 (Taiwan^19F-14), CC315 (Poland^6B-20) and CC180 (Netherlands³-31), accounting for 43.0%, 13.9% and 5.1%, respectively. In the post-vaccine period, a shift in the genetic structure of serotype 19A was found, with a significant increase of PMEN-14 (CC320) and a concurrent decrease of the major clone Denmark¹⁴-32 (CC230) observed prior to PCV10 introduction in Bulgaria.

CONCLUSIONS

Clonality was found behind the wide distribution of MDR capsular types 19A, 6C, 23A and 3 following vaccine introduction, and a highly multiresistant and virulent clone Taiwan^19F-14/ST320 has emerged as a common pathogen in children.

Antimicrobial resistance, penicillin-binding protein sequences, and pilus islet carriage in relation to clonal evolution of Streptococcus pneumoniae serotype 19A in Russia, 2002-2013

Clonal changes of serotype 19A pneumococci have been appreciated in conjunction with growing prevalence of this serotype after implementation of the seven-valent pneumococcal conjugate vaccine (PCV7). In the present study, we characterized serotype 19A pneumococci collected in Russia within a decade preceding the implementation of PCV vaccination and described their clonal evolution. We retrospectively analyzed non-invasive serotype 19A isolates collected in 2002-2013. All isolates were subjected to multilocus sequence typing, antimicrobial susceptibility testing, determination of macrolide resistance genotype, molecular detection of pilus islet (PI) carriage, sequencing of penicillin-binding protein (PBP) genes. A total of 49 serotype 19A isolates represented 25 sequence types, of which 14 were newly described. The majority of isolates were distributed among clonal complex (CC) 663 (28%), CC230 (25%), CC156, and CC320 (14% each). CC663 and CC156 dominated in 2003, but were replaced by CC230 and CC320 later on; CC320 was only evident starting 2010. All isolates of CC663 and CC156 carried PI1; CC320 possessed both PI1 and PI2. The overall rate of altered amino acids in penicillin-nonsusceptible isolates was 13·9%, 7·2%, and 8·7% for PBP1a, PBP2b, and PBP2x, respectively. Our findings demonstrate that the clonal structure of serotype 19A pneumococci may evolve without PCV pressure.

Serotypes and Clonal Diversity of Streptococcus pneumoniae Causing Invasive Disease in the Era of PCV13 in Catalonia, Spain

The aim of this study was to study the serotypes and clonal diversity of pneumococci causing invasive pneumococcal disease in Catalonia, Spain, in the era of 13-valent pneumococcal conjugate vaccine (PCV13). In our region, this vaccine is only available in the private market and it is estimated a PCV13 vaccine coverage around 55% in children. A total of 1551 pneumococcal invasive isolates received between 2010 and 2013 in the Molecular Microbiology Department at Hospital Sant Joan de Déu, Barcelona, were included. Fifty-two serotypes and 249 clonal types-defined by MLST-were identified. The most common serotypes were serotype 1 (n = 182; 11.7%), 3 (n = 145; 9.3%), 19A (n = 137; 8.8%) and 7F (n = 122; 7.9%). Serotype 14 was the third most frequent serotype in children < 2 years (15 of 159 isolates). PCV7 serotypes maintained their proportion along the period of study, 16.6% in 2010 to 13.4% in 2013, whereas there was a significant proportional decrease in PCV13 serotypes, 65.3% in 2010 to 48.9% in 2013 (p<0.01). This decrease was mainly attributable to serotypes 19A and 7F. Serotype 12F achieved the third position in 2013 (n = 22, 6.4%). The most frequent clonal types found were ST306 (n = 154, 9.9%), ST191 (n = 111, 7.2%), ST989 (n = 85, 5.5%) and ST180 (n = 80, 5.2%). Despite their decrease, PCV13 serotypes continue to be a major cause of disease in Spain. These results emphasize the need for complete PCV13 vaccination.

Emerging non-PCV13 serotypes of noninvasive Streptococcus pneumoniae with macrolide resistance genes in northern Japan

In Japan, the 7-valent pneumococcal conjugate vaccine (PCV7) was introduced to the nation's routine immunization program in April 2013 and was replaced by the 13-valent pneumococcal conjugate vaccine (PCV13) in November 2013. Distribution of serotypes and macrolide resistance genotypes was investigated for a total of 1097 (975 children, 122 adults) and 960 (873 children, 87 adults) clinical isolates of Streptococcus pneumoniae from noninvasive infections in Hokkaido (northern main island of Japan) in the routine immunization periods for PCV7 and PCV13 (April–October 2013 and November 2013–November 2014, respectively). Serotype was determined by sequential multiplex PCR and additional genetic analyses. Macrolide resistance genes erm(B) and mef(A/E) were detected by multiplex PCR. Although the most prevalent serotypes in children were 23A and 6C in the PCV7 period, after replacement with PCV13, 19A became the most common, followed by 6C, 15A and 23A. Among adults, serotype 3 was consistently the most frequent throughout the study periods. Compared with values from the pre-PCV7 routine immunization period, PCV7 serotypes decreased from 48.3 to 3.3% in the PCV13 period among children, while the rates of non-PCV13 serotypes (particularly 15A, 23A, 11A, 10A and 35B) increased from 39.7 to 75.1% (p < 0.001). In the PCV13 period, erm(B), mef(A/E) and both of these genes were detected in 75.8, 31.6 and 11.3% of all isolates, respectively. Serotype 19A accounted for 76.9% of the isolates with both the macrolide resistance genes, and emerging non-PCV13 serotypes 15A, 15C and 23A mostly harboured erm(B).