Site-specific disease potential of individual Streptococcus pneumoniae serotypes in pediatric invasive disease, acute otitis media and acute conjunctivitis

Invasive Pneumococcal Disease and Potential Impact of Pneumococcal Conjugate Vaccines Among Adults, Including Persons Experiencing Homelessness-Alaska, 2011-2020

BACKGROUND

Adults aged ≥65 years, adults with certain underlying medical conditions, and persons experiencing homelessness are at increased risk for invasive pneumococcal disease (IPD). Two new pneumococcal conjugate vaccines, 15-valent pneumococcal conjugate vaccine (PCV15) and 20-valent pneumococcal conjugate vaccine (PCV20), were recently approved for use in US adults. We describe the epidemiology of IPD among Alaska adults and estimate the proportion of IPD cases potentially preventable by new vaccines.

METHODS

We used statewide, laboratory-based surveillance data to calculate and compare IPD incidence rates and 95% confidence intervals (CIs) among Alaska adults aged ≥18 years during 2011-2020 and estimate the proportion of IPD cases that were caused by serotypes in PCV15 and PCV20.

RESULTS

During 2011-2020, 1164 IPD cases were reported among Alaska adults for an average annual incidence of 21.3 cases per 100 000 adults per year (95% CI, 20.1-22.5). Incidence increased significantly during the study period (P < .01). IPD incidence among Alaska Native adults was 4.7 times higher than among non-Alaska Native adults (95% CI, 4.2-5.2). Among adults experiencing homelessness in Anchorage, IPD incidence was 72 times higher than in the general adult population (95% CI, 59-89). Overall, 1032 (89%) Alaska adults with IPD had an indication for pneumococcal vaccine according to updated vaccination guidelines; 456 (39%) and 700 (60%) cases were caused by serotypes in PCV15 and PCV20, respectively.

CONCLUSIONS

Use of PCV15 and PCV20 could substantially reduce IPD among adults in Alaska, including Alaska Native adults and adults experiencing homelessness.

Emerging pneumococcal serotypes in Iraq: scope for improved vaccine development

Pneumococcal disease is a global public health concern as it affects the young, aged and the immunocompromised. The development of pneumococcal vaccines and their incorporation in the immunization programs has helped to reduce the global burden of disease. However, serotype replacement and the emergence of non-vaccine serotypes as well as the persistence of a few vaccine serotypes underscores the need for development of new and effective vaccines against such pneumococcal serotypes. In the Middle East, places of religious mass gatherings are a hotspot for disease transmission in addition to the global risk factors. Therefore, the periodic surveillance of pneumococcal serotypes circulating in the region to determine the effectiveness of existing prevention strategies and develop improved vaccines is warranted. Currently, there is a lack of serotype prevalence data for Iraq due to inadequate surveillance in the region. Thus, this review aims to determine the pneumococcal serotypes circulating in Iraq which may help in the development and introduction of improved pneumococcal vaccines in the country.

Streptococcus pneumoniae nasal carriage patterns with and without common respiratory virus detections in households in Seattle, WA, USA before and during the COVID-19 pandemic

Background

Respiratory viruses might influence Streptococcus pneumoniae nasal carriage and subsequent disease risk. We estimated the association between common respiratory viruses and semiquantitative S. pneumoniae nasal carriage density in a household setting before and during the COVID-19 pandemic.

Methods

From November 2019-June 2021, we enrolled participants in a remote household surveillance study of respiratory pathogens. Participants submitted weekly reports of acute respiratory illness (ARI) symptoms. Mid-turbinate or anterior nasal swabs were self-collected at enrollment, when ARI occurred, and, in the second year of the study only, from household contacts after SARS-CoV-2 was detected in a household member. Specimens were tested using multiplex reverse-transcription PCR for respiratory pathogens, including S. pneumoniae, rhinovirus, adenovirus, common human coronavirus, influenza A/B virus, respiratory syncytial virus (RSV) A/B, human metapneumovirus, enterovirus, and human parainfluenza virus. We estimated differences in semiquantitative S. pneumoniae nasal carriage density, estimated by the inverse of S. pneumoniae relative cycle threshold (Crt) values, with and without viral detection for any virus and for specific respiratory viruses using linear generalized estimating equations of S. pneumoniae Crt values on virus detection adjusted for age and swab type and accounting for clustering of swabs within households.

Results

We collected 346 swabs from 239 individuals in 151 households that tested positive for S. pneumoniae (n = 157 with and 189 without ≥1 viruses co-detected). Difficulty breathing, cough, and runny nose were more commonly reported among individuals with specimens with viral co-detection compared to without (15%, 80% and 93% vs. 8%, 57%, and 51%, respectively) and ear pain and headache were less commonly reported (3% and 26% vs. 16% and 41%, respectively). For specific viruses among all ages, semiquantitative S. pneumoniae nasal carriage density was greater with viral co-detection for enterovirus, RSV A/B, adenovirus, rhinovirus, and common human coronavirus (P < 0.01 for each). When stratified by age, semiquantitative S. pneumoniae nasal carriage density was significantly greater with viral co-detection among children aged <5 (P = 0.002) and 5-17 years (P = 0.005), but not among adults aged 18-64 years (P = 0.29).

Conclusion

Detection of common respiratory viruses was associated with greater concurrent S. pneumoniae semiquantitative nasal carriage density in a household setting among children, but not adults.

Ocular streptococcal infections: A clinical and microbiological review

Streptococcus is a diverse bacterial genus that is part of the ocular surface microbiome implicated in conjunctivitis, keratitis, endophthalmitis, dacryocystitis, and orbital cellulitis which can lead to decreased visual acuity and require surgical intervention. The pathophysiology of S. pneumoniae is well established and the role of the polysaccharide capsule, pneumolysin, neuraminidases, and zinc metalloproteinases in ocular infections described. Additionally, key virulence factors of the viridans group streptococci such as cytolysins and proteases have been outlined, but there is a paucity of research on the remaining streptococcus species. These virulence factors tend to result in aggressive disease. Clinically, S. pneumoniae is implicated in 2.7-41.2% of bacterial conjunctivitis cases, more predominant in the pediatric population, and is implicated in 1.8-10.7% of bacterial keratitis isolates. Streptococcus bacteria are significantly implicated in acute postoperative, post-intravitreal, and bleb-associated endophthalmitis, responsible for 10.3-37.5, 29.4, and 57.1% of cases, respectively. Group A and B streptococcus endogenous endophthalmitis is rare, but has a very poor prognosis. Inappropriate prescription of antibiotics in cases of non-bacterial aetiology has contributed to increasing resistance, and a clinical index is needed to more accurately monitor this. Furthermore, there is an increasing need for prospective, surveillance studies of antimicrobial resistance in ocular pathogens, as well as point-of-care testing using molecular techniques.

Absence of Streptococcus pneumoniae Capsule Increases Bacterial Binding, Persistence, and Inflammation in Corneal Infection

The role of the pneumococcal polysaccharide capsule is largely unclear for Streptococcus pneumoniae keratitis, an ocular inflammatory disease that develops as a result of bacterial infection of the cornea. In this study, capsule-deficient strains were compared to isogenic parent strains in their ability to adhere to human corneal epithelial cells. One isogenic pair was further used in topical ocular infection of mice to assess the contribution of the capsule to keratitis. The results showed that non-encapsulated pneumococci were significantly more adherent to cells, persisted in significantly higher numbers on mouse corneas in vivo, and caused significant increases in murine ocular IL9, IL10, IL12-p70, MIG, and MIP-1-gamma compared to encapsulated S. pneumoniae. These findings indicate that the bacterial capsule impedes virulence and the absence of capsule impacts inflammation following corneal infection.

Antioxidant Properties and Structure-Antioxidant Activity Relationship of Allium Species Leaves

Allium is a genus that is widely consumed and used as traditional medicine in several countries. This genus has two major species, namely cultivated species and wild species. Cultivated species consist of A. cepa L., A. sativum L., A. fistulosum L. and A. schoenoprasum L. and wild species consist of A. ursinum L., A. flavum L., A. scorodoprasum L., A. vineale L. and A. atroviolaceum Boiss. Several studies report that the Allium species contain secondary metabolites such as polyphenols, flavonoids and tannins and have bioactivity such as antioxidants, antibacterial, antifungal, anti-inflammatory, pancreatic α-amylase, glucoamylase enzyme inhibitors and antiplatelets. This review summarizes some information regarding the types of Allium species (ethnobotany and ethnopharmacology), the content of compounds of Allium species leaves with various isolation methods, bioactivities, antioxidant properties and the structure-antioxidant activity relationship (SAR) of Allium compounds.

Effects of nasopharyngeal microbiota in respiratory infections and allergies

The human microbiome, which consists of a collective cluster of commensal, symbiotic, and pathogenic microorganisms living in the human body, plays a key role in host health and immunity. The human nasal cavity harbors commensal bacteria that suppress the colonization of opportunistic pathogens. However, dysbiosis of the nasal microbial community is associated with many diseases, such as acute respiratory infections including otitis media, sinusitis and bronchitis and allergic respiratory diseases including asthma. The nasopharyngeal acquisition of pneumococcus, which exists as a pathobiont in the nasal cavity, is the initial step in virtually all pneumococcal diseases. Although the factors influencing nasal colonization and elimination are not fully understood, the adhesion of opportunistic pathogens to nasopharyngeal mucosa receptors and the eliciting of immune responses in the host are implicated in addition to bacterial microbiota properties and colonization resistance dynamics. Probiotics or synbiotic interventions may show promising and effective roles in the adjunctive treatment of dysbiosis; however, more studies are needed to characterize how these interventions can be applied in clinical practice in the future.

Invasive disease potential of Streptococcus pneumoniae serotypes before and after 10-valent pneumococcal conjugate vaccine introduction in a rural area, southern Mozambique

BACKGROUND

Invasive pneumococcal disease (IPD) is a significant cause of morbidity and mortality among children worldwide. In April 2013, Mozambique introduced 10-valent PCV (PCV10) into the National Expanded Program on immunization using a three-dose schedule at 2, 3, and 4 months of age. We aimed to evaluate the invasive disease potential of pneumococcal serotypes among children in our region before and after PCV10 introduction.

METHODS

We used data from ongoing population-based surveillance for IPD and cross-sectional pneumococcal carriage surveys among children aged <5 years in Manhiҫa, Mozambique. To determine the invasive disease potential for each serotype pre- and post-PCV10 introduction, odds ratios (OR) and 95% confidence intervals (95% CI) were calculated comparing serotype-specific prevalence in IPD and in carriage. For each serotype, OR and 95% CI > 1 indicated high invasive disease potential and OR and 95% CI < 1 indicated low invasive disease potential.

RESULTS

In the pre-PCV10 period, 524 pneumococcal isolates were obtained from 411 colonized children and IPD cases were detected in 40 children. In the post-PCV10 period, 540 pneumococcal isolates were obtained from 507 colonized children and IPD cases were detected in 30 children. The most prevalent serotypes causing IPD pre-PCV10 were 6A (17.5%), 6B (15.0%), 14 (12.5%), 23F (10.0%) and 19F (7.5%), and post-PCV10 were 6A (36.7%), 13 (10%), 1 (10.0%), 6B (6.7%) and 19A (6.7%). Serotypes associated with high invasive disease potential pre-PCV10 included 1 (OR:22.3 [95% CI 2.0; 251.2]), 6B (OR:3.1 [95% CI 1.2; 8.1]), 14 (OR: 3.4 [95% CI 1.2; 9.8]) and post-PCV10 included serotype 6A (OR:6.1[95% CI 2.7; 13.5]).

CONCLUSION

The number of serotypes with high invasive disease potential decreased after PCV10 introduction. Serotype 6A, which is not included in PCV10, was the most common cause of IPD throughout the study and showed a high invasive potential in the post-PCV10 period.

Pneumococcal serotype 19A is the major cause of pediatric acute otitis media with ruptured tympanic membrane in Addis Ababa, Ethiopia, 5 years after the introduction of the ten-valent pneumococcal conjugate vaccine

INTRODUCTION

In Ethiopia, there is a lack of data on pneumococcal serotypes causing acute otitis media (AOM) in children. We aimed to study the etiology, pneumococcal serotypes and antimicrobial resistance patterns of isolates from children with AOM with spontaneous perforation of the tympanic membrane (SPTM).

METHODS

We carried out a prospective observational study in children with AOM with SPTM, aged 0-15 years in Addis Ababa, Ethiopia. Middle ear fluid was collected using sterile swabs, cultured and antibiotic susceptibility testing was performed. Serotypes of Streptococcus pneumoniae were determined by sequencing the cpsB gene and by the Quellung reaction.

RESULTS

A total of 55 children were enrolled. Out of 55 samples that were cultured, 52 (94.5%) were culture positive for a total of 66 bacterial species, and 56.4% (31/55) samples were positive for 41 (62.1%) known pathogenic bacterial species. The most common pathogenic bacterial isolates were S. pneumoniae (36.6%), Staphylococcus aureus (19.5%), Streptococcus pyogenes (14.6%) and Haemophilus influenzae (12.2%). Serotype 19A (73.3%) was the predominant pneumococcal serotype. There was a high rate of non-susceptibility to penicillin (86.6%) and trimethoprim/sulfamethoxazole (80%) among pneumococcal isolates. Out of 21 different isolates tested for amoxicillin susceptibility, 15 (71.4%) were resistant.

CONCLUSIONS

Pneumococcal serotype 19A was the predominant cause of AOM with SPTM in children in Addis Ababa, Ethiopia, 5 years after introduction of PCV10. There was a high rate of resistance to commonly prescribed antibiotics. The study highlights the need for wide scale surveillance of the etiology and antimicrobial susceptibility of AOM in Ethiopian children.

Nasopharyngeal Carriage of Invasive Pneumococcal Serotypes During Childhood Community-Acquired Alveolar Pneumonia Is Associated With Specific Clinical Presentation

Background

Streptococcus pneumoniae (Pnc) serotypes differ in invasive potential. We examined whether community-acquired alveolar pneumonia (CAAP) in children carrying commonly recognized pneumonia invasive pneumococcal serotypes ([PnIST] 1, 5, 7F, 14, and 19A) differs from CAAP in children carrying less invasive serotypes (non-PnIST) or no Pnc (Pnc-neg).

Methods

Children <5 years, visiting the only regional Pediatric Emergency Room, with radiologically proven CAAP were enrolled. Nasopharyngeal cultures were processed for pneumococcal isolation and serotyping. Clinical and demographic characteristics were recorded. The study was conducted before pneumococcal conjugate vaccine implementation in Israel.

Results

A total of 1423 CAAP episodes were recorded: PnIST, 300 (21.1%); non-PnIST, 591 (41.5%); and Pnc-neg, 532 (37.4%). After adjustment for age, ethnicity, seasonality, and previous antibiotics, the following variables were positively associated with PnIST carriage compared with both groups: temperature ≥39°C, peripheral white blood cell count ≥20 000/mm3, C-reactive protein ≥70.0 mg/L, and serum sodium <135 mEq/L. Lower oxygen saturation, viral detection, and comorbidities were negatively associated with Pn-IST carriage (odds ratios, <1.0). Differences between non-PnIST carriers and Pnc-neg groups were smaller or nonsignificant.

Conclusions

Young children with CAAP carrying common PnIST had a lower proportion of comorbidities, hypoxemia, and viral detection and had more intense systemic inflammatory response than those carrying non-PnIST or not carrying Pnc.

Interaction With Nontypeable Haemophilus influenzae Alters Progression of Streptococcus pneumoniae From Colonization to Disease in a Site-Specific Manner

BACKGROUND

Pneumococci and nontypeable Haemophilus influenzae (NTHi) often cocolonize children. The impact of species interactions on disease risk across the upper respiratory mucosa is not known.

METHODS

We analyzed data from 4104 acute conjunctivitis (AC) cases, 11 767 otitis media (OM) cases, and 1587 nasopharyngeal specimens collected from Israeli children before pneumococcal conjugate vaccine introduction. We compared pneumococcal serotype distributions with NTHi present and absent, and compared single-species and mixed-species rates of serotype-specific progression from colonization to AC and OM.

RESULTS

Pneumococcal serotypes causing single-species OM (NTHi absent) were less diverse than colonizing serotypes and also less diverse than those causing mixed-species OM; colonizing and OM-causing pneumococcal serotype distributions were more similar to each other with NTHi present than with NTHi absent. In contrast, serotype diversity did not differ appreciably between colonizing and AC-causing pneumococci, regardless of NTHi co-occurrence. The similarity of colonizing and AC-causing pneumococcal serotype distributions was consistent in the presence and absence of NTHi. Differences in rates that pneumococcal serotypes progressed from colonization to disease were reduced in both AC and OM when NTHi was present.

CONCLUSIONS

Interactions with NTHi may alter progression of pneumococcal serotypes to diseases of the upper respiratory mucosa in a site-specific manner.

Bacterial causes of otitis media with spontaneous perforation of the tympanic membrane in the era of 13 valent pneumococcal conjugate vaccine

After pneumococcal conjugate vaccine (PCV) implementation, the number of acute otitis media (AOM) episodes has decreased, but AOM still remains among the most common diagnoses in childhood. From 2% to 17% of cases of AOM feature spontaneous perforation of the tympanic membrane (SPTM). The aim of this study was to describe the bacteriological causes of SPTM 5 to 8 years years after PCV13 implementation, in 2010. From 2015 to 2018, children with SPTM were prospectively enrolled by 41 pediatricians. Middle ear fluid was obtained by sampling spontaneous discharge. Among the 470 children with SPTM (median age 20.8 months), no otopathogen was isolated for 251 (53.4% [95% CI 48.8%;58.0%]): 47.1% of infants and toddlers, 68.3% older children (p<0.001). Among children with isolated bacterial otopathogens (n = 219), non-typable Haemophilus influenzae (NTHi) was the most frequent otopathogen isolated (n = 106, 48.4% [95% CI 41.6%;55.2%]), followed by Streptoccocus pyogenes (group A streptococcus [GAS]) (n = 76, 34.7% [95% CI 28.4%;41.4%]) and Streptococcus pneumoniae (Sp) (n = 61, 27.9% [95% Ci 22.0%;34.3%]). NTHi was frequently isolated in infants and toddlers (53.1%), whereas the main otopathogen in older children was GAS (52.3%). In cases of co-infection with at least two otopathogens (16.9%, n = 37/219), NTHi was frequently involved (78.4%, n = 29/37). When Sp was isolated, PCV13 serotypes accounted for 32.1% of cases, with serotype 3 the main serotype (16.1%). Among Sp strains, 29.5% were penicillin-intermediate and among NTHi strains, 16.0% were β-lactamase-producers. More than 5 years after PCV13 implementation, the leading bacterial species recovered from AOM with SPTM was NTHi for infants and toddlers and GAS for older children. In both age groups, Sp was the third most frequent pathogen and vaccine serotypes still played an important role. No resistant Sp strains were isolated, and the frequency of β-lactamase-producing NTHi did not exceed 16%.

Emergence of Streptococcus pneumoniae Serotype 12F after Sequential Introduction of 7- and 13-Valent Vaccines, Israel

Israel implemented use of 7- and 13-valent pneumococcal vaccine in 2009 and 2010, respectively. We describe results of prospective, population-based, nationwide active surveillance of Streptococcus pneumoniae serotype 12F (Sp12F) invasive pneumococcal disease (IPD) dynamics in the 7 years after vaccine introduction. Of 4,573 IPD episodes during July 2009-June 2016, a total of 434 (9.5%) were caused by Sp12F. Sp12F IPD rates (cases/100,000 population) increased in children <5 years of age, from 1.44 in 2009-2010 to >3.9 since 2011-2012, followed by an increase in all ages. During 2011-2016, Sp12F was the most prevalent IPD serotype. Sp12F isolates were mostly penicillin nonsusceptible (MIC >0.06 µg/mL; MIC₅₀ = 0.12) and predominantly of sequence type 3774), a clone exclusively found in Israel (constituting ≈90% of isolates in 2000-2009). The sharp increase, long duration, and predominance of Sp12F IPD after vaccine implementation reflect a single clone expansion and may represent more than a transient outbreak.

Biofilm production by Haemophilus influenzae and Streptococcus pneumoniae isolated from the nasopharynx of children with acute otitis media

Background

Biofilm production by Haemophilus influenzae and Streptococcus pneumoniae has been implicated in the pathogenesis of otitis media, mainly in chronic and recurrent cases. We studied the “in vitro” biofilm production by these 2 species isolated alone or together from the nasopharynx of children with acute otitis media.

Methods

The studied strains were from 3 pneumococcal conjugate vaccine (PCV) periods: pre-PCV7, post-PCV7/pre-PCV13 and post-PCV13. A modified microtiter plate assay with crystal violet stain was used to study the biofilm production of 182 H. influenzae and 191 S. pneumoniae strains.

Results

Overall, 117/181 (64.6%) H. influenzae and 128/191 (66.8%) S. pneumoniae strains produced biofilm. The proportion of biofilm-producing H. influenzae strains was greater with than without the isolation of S. pneumoniae in the same sample (75.5% vs 52.3%, p = 0.001). Conversely, the proportion of biofilm-producing S. pneumoniae strains was not affected by the presence or not of H. influenzae (66.3% vs 67.4%). S. pneumoniae serotypes 6B, 15B/C, 19A, 35F and 35B were the better biofilm producers (80%). Serotypes 11A, 14, 15A, 19F and 19A were more associated with H. influenzae biofilm-producing strains. Overall, 89/94 (94.6%) of cases with combined isolation showed biofilm production by S. pneumoniae or H. influenzae.

Conclusion

This study emphasizes the high proportion of biofilm production by H. influenzae and S. pneumoniae strains isolated from the nasopharynx of children with acute otitis media, which reinforces the results of studies suggesting the importance of biofilm in the pathogenesis of acute otitis media.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3657-9) contains supplementary material, which is available to authorized users.

Changes in the serotype distribution of Streptococcus pneumoniae causing otitis media after PCV13 introduction in Spain

One of the beneficial effects of pneumococcal conjugate vaccines (PCVs) has been a decrease in the incidence of non-invasive infections, such as otitis media (OM) caused by vaccine serotypes. In this study, we analyzed the epidemiology of pneumococcal OM before and after PCV13 introduction in 2010. Between 2008 and 2016, the middle ear exudates from 2653 children under 14 years of age with OM were studied in two Spanish provinces (Gipuzkoa and Barcelona), and S. pneumoniae was isolated in 235 (8.9%) of cases. The 204 available isolates were serotyped and distributed in three 3-year periods: one before and two after PCV13 introduction (early and late post-PCV13). A significant decrease in the rate of OM caused by S. pneumoniae was observed mainly due to a decrease in infections caused by all PCV13 serotypes, although exceptions were observed including the persistence of serotype 3 in Gipuzkoa and a weak re-emergence of serotype 19F in both regions. The rate and diversity of non-PCV13 serotypes increased in both regions and an emerging clone causing OM was detected in each region: serotype 23B ST2372 in Gipuzkoa and serotype 11A ST838/ST6521 in Barcelona. The introduction of PCV13 has been followed by a change in the epidemiology of pneumococcal OM, with a decrease in the rate of vaccine serotypes accompanied by an increase in the diversity of non-vaccine serotype and the clonal spreading of different single clones in each region.

Effect of the introduction of pneumococcal conjugate vaccines on serotype prevalence in Kuwait and Saudi Arabia

BACKGROUND

Streptococcus pneumoniae infection is a major cause of morbidity and mortality. Although pneumococcal disease burden in Kuwait and Saudi Arabia is considered high, comprehensive surveillance data on pneumococcal conjugate vaccine (PCV) effects are lacking.

METHODS

Sterile isolates from patients in Kuwait (2003-2016) and Saudi Arabia (aged ≤5 years, 2000-2010; all patients, 2011-2015) were included. Serotyped isolates were classified by inclusion in the 7-valent (PCV7) or 13-valent PCV (PCV13); isolates of other serotypes were classified as "non-PCV13". Isolate frequency (number of isolates/year) and classification of isolates according to vaccine type were assessed by period (before PCV, after PCV7, and after PCV13 introduction).

RESULTS

In Kuwait, the frequency of collected isolates was highest after PCV7 introduction. Decreased frequency of PCV7 serotypes was seen after PCV13 introduction compared with before PCV and after PCV7 introduction. Increased frequency of the 6 additional serotypes in PCV13 and non-PCV13 serotypes was observed after PCV7 introduction with a subsequent decrease in the 6 additional serotypes in PCV13 and non-PCV13 serotypes after PCV13 introduction. The percentage of isolates of vaccine serotypes in Kuwait decreased over time. In Saudi Arabia, the frequency of collected isolates was highest after PCV7 introduction. An increased frequency of PCV7 serotypes was observed after PCV7 introduction, with a further decrease after PCV13 introduction. For the 6 additional serotypes in PCV13, an increased frequency was seen after PCV7 and PCV13 introduction compared to before PCV introduction. For non-PCV13 serotypes, an increased frequency was observed after PCV13 introduction compared to after PCV7 introduction. The percentage of isolates covered by PCV13 serotypes was similar across periods, while a substantial decrease in isolates covered by PCV7 was seen after PCV13 introduction.

CONCLUSION

PCVs in Kuwait and Saudi Arabia resulted in decreased frequency of some vaccine serotypes and an emergence of some non-PCV13 serotypes. Further investigation is warranted.

Pan-serotype Reduction in Progression of Streptococcus pneumoniae to Otitis Media After Rollout of Pneumococcal Conjugate Vaccines

Background

Reductions in otitis media (OM) burden following rollout of pneumococcal conjugate vaccines (PCVs) have exceeded predictions of vaccine impact. In settings with active surveillance, reductions in OM caused by vaccine-targeted pneumococcal serotypes have co-occurred with reductions in OM caused by other pathogens carried in the upper-respiratory tract of children. To understand these changes, we investigated the progression of vaccine-targeted and non-vaccine pneumococcal serotypes from carriage to OM before and after vaccine rollout.

Methods

Nasopharyngeal carriage prevalence of pneumococcus was monitored in prospective studies of Bedouin and Jewish children <3 years old in southern Israel between 2004 and 2016. Incidence of OM necessitating middle-ear fluid culture (predominantly complex OM including recurrent, spontaneously-draining, non-responsive, and chronic cases) was monitored via prospective, population-based active surveillance. We estimated rates of pneumococcal serotype-specific progression from carriage to disease before and after rollout of PCV7/13, measured as OM incidence per carrier. We pooled serotype-specific estimates using Bayesian random-effects models.

Results

On average, rates of progression declined 92% (95% credible interval: 79-97%) and 80% (46-93%) for PCV7/13 serotypes among Bedouin and Jewish children <12 months old, respectively, and 32% (-58-71%) and 61% (-5-86%) among children aged 12-35m. For non-vaccine serotypes, rates of progression among Bedouin and Jewish children aged <12m declined 74% (55-85%) and 43% (4-68%), respectively.

Conclusions

Vaccine-targeted and non-vaccine pneumococcal serotypes showed lower rates of progression to complex OM after rollout of PCV7/13. Early-life OM episodes historically associated with vaccine-serotype pneumococci may impact the susceptibility of children to OM progression.

Pneumococcal Phenotype and Interaction with Nontypeable Haemophilus influenzae as Determinants of Otitis Media Progression

All-cause otitis media (OM) incidence has declined in numerous settings following introduction of pneumococcal conjugate vaccines (PCVs) despite increases in carriage of nonvaccine pneumococcal serotypes escaping immune pressure. To understand the basis for the declining incidence, we assessed the intrinsic capacity of pneumococcal serotypes to cause OM independently and in polymicrobial infections involving nontypeable Haemophilus influenzae (NTHi) using samples obtained from middle ear fluid and nasopharyngeal cultures before PCV7/13 rollout. Data included samples from OM episodes (11,811) submitted for cultures during a 10-year prospective study in southern Israel and nasopharyngeal samples (1,588) from unvaccinated asymptomatic children in the same population. We compared data representing pneumococcal serotype diversity across carriage and disease isolates with and without NTHi coisolation. We also measured associations between the pneumococcal phenotype and the rate of progression from colonization to OM in the presence and absence of NTHi. Whereas pneumococcal serotype diversity was lower in single-species OM than in single-species colonization, levels of serotype diversity did not differ significantly between colonization and OM in mixed-species episodes. Serotypes differed roughly 100-fold in progression rates, and those differences were attenuated in polymicrobial episodes. Vaccine serotype pneumococci had higher rates of progression than nonvaccine serotypes. While serotype invasiveness was a weak predictor of the OM progression rate, efficient capsular metabolic properties-traditionally thought to serve as an advantage in colonization-predicted an enhanced rate of progression to complex OM. The lower capacity of nonvaccine serotypes to cause OM may partially account for reductions in all-cause OM incidence despite serotype replacement in carriage following rollout of PCVs.

Deconstructing Pneumococcal Progression from Colonization to Disease

Despite advances in treatment and prevention, the pneumococcus continues to be a dominant cause of severe pneumonia and sepsis and of otitis media, sinusitis, and nonbacteremic pneumonia. Lewnard and colleagues (Infect Immun 86:e00727-17, 2018, https://doi.org/10.1128/IAI.00727-17) used a unique data set of nasopharyngeal and middle ear fluid samples to provide further insight into the progression of nasopharyngeal pneumococcal colonization to disease. They report the comparative rate of progression from colonization to otitis media by serotype, providing insight into how conjugate vaccines that do not reduce the overall prevalence of pneumococci in the nasopharynx dramatically impact the incidence of acute and complex otitis media.

Antibiotic Resistance of Potential Otopathogens Isolated From Nasopharyngeal Flora of Children With Acute Otitis Media Before, During and After Pneumococcal Conjugate Vaccines Implementation

BACKGROUND

To re-evaluate antibiotic strategies for acute otitis media (AOM) in young children, we analyzed the trends of nasopharyngeal carriage and antibiotic resistance of Streptococcus pneumoniae (Sp), Haemophilus influenzae (Hi) and Moraxella catarrhalis (Mc) isolated from young children with AOM during a 16-year period.

METHODS

This cross-sectional study analyzed from 2001 to 2016 the nasopharyngeal carriage of Sp, Hi and Mc of young children with AOM. Medical history and physical findings were reported. Periods were defined by pneumococcal conjugate vaccine (PCV) introduction. We separately analyzed the 13-valent PCV (PCV13) period, which started after 2013.

RESULTS

During the study, 12,973 children with AOM were enrolled by 138 pediatricians. By comparing the first and last PCV periods, the proportion of children in day care centers and that of AOM with conjunctivitis significantly increased. The proportion of penicillin nonsusceptible Sp carriage significantly decreased during the study, with 0.8% of penicillin-resistant strains isolated in the PCV13 period, but that of β-lactamase-producing Hi continually increased to 23.6% in 2016. The level of Mc β-lactamase-producing strains remained high (>97%). In the PCV13 period, the main predictors of β-lactamase-producing Hi carriage were conjunctivitis (adjusted odds ratio = 6.0, 95% confidence interval [4.7-7.7]) and attending a day care center (2.4 [1.7-3.5]).

CONCLUSIONS

In the PCV13 period, the proportion of penicillin-resistant Sp carriage was very low and that of β-lactamase-producing Hi carriage did not exceed 20% among children with AOM and without conjunctivitis. Our results suggest that amoxicillin may remain the first-line antibiotic treatment for AOM in young children except for those with conjunctivitis, for which amoxicillin-clavulanate is still the best antibiotic.

Surveillance of pneumococcal colonization and invasive pneumococcal disease reveals shift in prevalent carriage serotypes in Massachusetts' children to relatively low invasiveness

BACKGROUND

Following the introduction of pneumococcal conjugate vaccines (PCV), overall nasopharyngeal colonization rates have not changed significantly, however a dramatic and sustained decline in invasive pneumococcal disease (IPD) in children was observed in every setting where the PCVs were implemented. We aimed to describe the differences in invasive disease potential of serotypes that are common colonizers in pre- and post-vaccine eras in order to provide further insight in our understanding of dynamic epidemiology of pneumococcal diseases.

METHODS

Using data from surveillance of nasopharyngeal carriage and enhanced surveillance for IPD, a serotype specific "invasive capacity (IC)" was computed by dividing the incidence of IPD due to serotype x by the carriage prevalence of that same serotype in children <7years of age in Massachusetts. We have evaluated the serotype specific invasive capacity in two periods; pre-PCV13 (2001/02, 2003/04, 2006/07, 2008/09) and post-PCV13 (2010/11 and 2013/14), and by age groups; <24monthsvs. ≥24months.

RESULTS

An approximate 50-fold variation in the point estimate was observed between the serotypes having the highest (7F, 38, 19A, 3, 33F) and the lowest (6C, 35B, 21, 11A, 23B and 23A) computed serotype specific invasive disease potential. In the post-PCV13 era (6C, 35B, 11A, 23B and 23A), 5 of the 7 most common serotypes colonizing the nasopharynx were serotypes with the lowest invasive capacity. Serotype specific invasive capacity trended down in older children for majority of the serotypes, and serotypes 3, 10A and 19A had significantly lower invasive capacity in children older than 24months of age compared to younger children.

CONCLUSION

Invasive capacity differs among serotypes and likely by age. Point estimates of IC for most of the common serotypes colonizing children in Massachusetts in post-PCV13 era were low and likely explain the continued reduction in IPD from the pre-PCV era in the absence of specific protection against these serotypes.

Burden of Culture-Confirmed Pediatric Pneumococcal Pneumonia in Latin America and the Caribbean: A Systematic Review and Meta-Analysis

BACKGROUND

Pneumococcal pneumonia (PP) causes almost one in five deaths in children younger than 5 years worldwide. In Latin America and the Caribbean (LAC), pneumonia causes 14% of all deaths. Although pneumococcal disease is a vaccine-preventable disease that accounts for a significant proportion of this burden, the decision-making process to introduce pneumococcal conjugate vaccines in official schedules is still complex in LAC. Confirmed PP cases and epidemiology are the basis for broader projections.

OBJECTIVE

To gather all the information available in the LAC region to assist decision makers.

METHODS

We performed a systematic review of studies of consolidating and culture-confirmed pediatric PP in LAC (2000-2016) using a generic academic Internet search and search engines without language restrictions. Pairs of reviewers independently selected and assessed the studies' methodological quality. We analyzed meta-information on pneumococcal serotypes available from the SIREVA laboratory-based surveillance system.

RESULTS

A total of 35 out of 750 initially identified studies were included. In the age group between 0 and 59 years, the incidence of culture-confirmed PP ranged from 10.2 to 43.0/100,000 children, with a pooled incidence of 20.4/100,000 children (95% confidence interval 0.0-123.2). Mortality ranged from 0.4 to 5.7/100,000 children, and the pooled mortality was 2.9/100,000 children (95% confidence interval 0.3-8.2). The pooled serotype distribution from surveillance data showed that serotypes 14, 1, and 6B were the most frequent serotypes in LAC, all included in licensed vaccines.

CONCLUSIONS

Studies on confirmed pediatric PP were scarce in LAC in 2000 to 2016. Epidemiology indicators and health resource use are still poorly defined.

Panel 4: Report of the Microbiology Panel

Objective To perform a comprehensive review of the literature from July 2011 until June 2015 on the virology and bacteriology of otitis media in children. Data Sources PubMed database of the National Library of Medicine. Review Methods Two subpanels comprising experts in the virology and bacteriology of otitis media were created. Each panel reviewed the relevant literature in the fields of virology and bacteriology and generated draft reviews. These initial reviews were distributed to all panel members prior to meeting together at the Post-symposium Research Conference of the 18th International Symposium on Recent Advances in Otitis Media, National Harbor, Maryland, in June 2015. A final draft was created, circulated, and approved by all panel members. Conclusions Excellent progress has been made in the past 4 years in advancing our understanding of the microbiology of otitis media. Numerous advances were made in basic laboratory studies, in animal models of otitis media, in better understanding the epidemiology of disease, and in clinical practice. Implications for Practice (1) Many viruses cause acute otitis media without bacterial coinfection, and such cases do not require antibiotic treatment. (2) When respiratory syncytial virus, metapneumovirus, and influenza virus peak in the community, practitioners can expect to see an increase in clinical otitis media cases. (3) Biomarkers that predict which children with upper respiratory tract infections will develop otitis media may be available in the future. (4) Compounds that target newly identified bacterial virulence determinants may be available as future treatment options for children with otitis media.

Streptococcus pneumoniae Serotypes and Antibiotic Susceptibility Patterns in Middle Ear Fluid Isolates During Acute Otitis Media and Nasopharyngeal Isolates During Community-acquired Alveolar Pneumonia in Central Romania

BACKGROUND

Streptococcus pneumoniae is a common cause of community-acquired alveolar pneumonia (CAAP) and acute otitis media (AOM) in children. Romania has high rates of S. pneumoniae antibiotic resistance. The pneumococcal conjugated vaccines (PCVs) are not being used routinely in this country. The aims of the study were as follows: 1) to compare pneumococcal antibiotic resistance patterns in AOM and CAAP in children from central Romania and 2) to compare differences in the distribution of pneumococcal serotypes isolated from the middle ear fluid (MEF) of children with AOM and from the nasopharynx (NP) of children with CAAP.

METHODS

Children younger than 5 years old with AOM or with radiologically confirmed CAAP were prospectively enrolled. Samples from MEF and NP were evaluated for antibiotic susceptibility and serotyping.

RESULTS

Eighty-eight children with CAAP and 68 with AOM were enrolled. Of the MEF and CAAP isolates, 64 (94.1%) and 79 (89.7%) were penicillin nonsusceptible, respectively. The pneumococcal serotypes distribution in AOM was similar to those in CAAP except for serotype 19F, which was more common in AOM. Overall, 89.7% and 85.8% of all serotypes in AOM and CAAP patients, respectively, were covered by 13-valent PCV.

CONCLUSIONS

MEF and NP-CAAP S. pneumoniae isolates were similar in regard to serotype distribution and antibiotic resistance. S. pneumoniae antibiotic resistance rates were extremely high. Thirteen-valent PCV has the potential to reduce both the burden of disease as well as the rates of antibiotic-resistant S. pneumoniae in both diseases.

TLR2 promotes macrophage recruitment and Streptococcus pneumoniae clearance during mouse otitis media

BACKGROUND

The natural course of otitis media (OM) in most children is acute and self-limiting; however, approximately 10-20% of children can experience persistent or recurrent OM. Determining the host factors that influence outcome of OM will help us design better therapies. This study focused on the role of Toll-like receptor 2 (TLR2) in a pneumococcal OM mouse model.

METHODS

The middle ears (MEs) of wild-type (WT) and TLR2^-/- mice were inoculated with Streptococcus pneumoniae (Spn) serotype 19F via transbullar injection. ME TLR2 expression in WT mice was determined by qRT-PCR and immunofluorescence. ME pathological manifestations, inflammatory response, and pneumococcal clearance between WT and TLR2^-/- mice were compared after Spn inoculation.

RESULTS

TLR2 expression in ME mucosa was markedly enhanced following infection with Spn in WT mice. In contrast to WT mice, TLR2^-/- mice exhibited unaffected early ME inflammatory response. During late stage of ME infection, however, the absence of TLR2 can lead to reduced macrophage recruitment, impaired Spn clearance, and prolonged ME inflammation.

CONCLUSION

Our results demonstrate that TLR2 signaling is critical for bacterial clearance and timely resolution of inflammation in OM induced by Spn.

Using Pneumococcal Carriage Data to Monitor Postvaccination Changes in the Incidence of Pneumococcal Otitis Media

Pneumococcal conjugate vaccines (PCVs) have substantially reduced the burden of pneumococcal disease, including the incidence of otitis media (OM). However, in most countries, no surveillance exists to monitor the change in pneumococcal OM incidence after the introduction of PCVs. We explored whether measuring pneumococcal carriage was a useful surrogate for monitoring postvaccination changes in the incidence of pneumococcal OM. The 7-valent PCV was introduced to Israel's national immunization program in July 2009 and gradually replaced by the 13-valent PCV starting in November 2010. Each day since 2009, nasopharyngeal swabs have been obtained from the first 4 Bedouin children and the first 4 Jewish children who were younger than 5 years old and attended a pediatric emergency room in southern Israel. During the same time, OM surveillance in southern Israel included all children younger than 2 years of age who were diagnosed with OM and had undergone a middle-ear fluid culture. The relative change in the prevalence of vaccine-serotype (VT) pneumococcal carriage was predictive of the relative change in incidence of OM due to VT pneumococcus. However, the serotype replacement observed in non-VT carriage is not paralleled in the incidence of OM due to non-VT pneumococcus. This could indicate that there are more complex mechanisms of the immune response involved in preventing initial and consecutive episodes of OM, which has been changed through declining prevalence of the most virulent serotypes as a result of vaccination.

Prevention of early episodes of otitis media by pneumococcal vaccines might reduce progression to complex disease

Otitis media is a common childhood infection of the middle ear and a major cause of morbidity. This multifactorial disease manifests as a spectrum of clinical syndromes from uncomplicated acute otitis media to more complex recurrent and chronic cases (frequently polymicrobial), with the major pathogens involved being Streptococcus pneumoniae and non-typeable Haemophilus influenzae. Pneumococcal conjugate vaccines (PCVs) target only a few serotypes that cause otitis media; however, results from studies suggest that existing PCVs can prevent early episodes of disease associated with vaccine serotypes, resulting in a reduction of subsequent complex cases caused by non-vaccine serotypes and other otopathogens, which contribute considerably to the disease burden. In this Review, we discuss the role of pneumococcus in the disease continuum and assess clinical evidence showing the effect of prevention of early episodes on the complex interplay between bacterial species implicated in otitis media.

Density, Serotype Diversity, and Fitness of Streptococcus pneumoniae in Upper Respiratory Tract Cocolonization With Nontypeable Haemophilus influenzae

BACKGROUND

 Coinfections by Streptococcus pneumoniae and nontypeable Haemophilus influenzae (NTHi) are frequently implicated in complex otitis media. Whereas upper respiratory tract carriage precedes disease for both pathogens, interactions between species in cocolonized hosts are poorly understood. We compared colonization densities and the diversity and fitness of pneumococcal serotypes in single-species and mixed-species colonization.

METHODS

 We analyzed nasopharyngeal pneumococcal carriage and nasopharyngeal and oropharyngeal NTHi carriage in 13 541 samples collected over 6909 study visits from 769 children 2-30 months old in a 7-valent pneumococcal conjugate vaccine dosing trial. We measured density associations between the species and compared pneumococcal serotype diversity during and in the absence of NTHi colonization. We used logistic regression to quantify associations between NTHi colonization and previously published pneumococcal serotype factors related to fitness.

RESULTS

 Densities of the 2 species were positively associated when they co-occur in the nasopharynx. NTHi colonization was associated with reduced pneumococcal serotype diversity among children 2-18 months old and was more prevalent among children carrying pneumococcal serotypes with greater capsular thickness, neutrophil resistance, and metabolic efficiency.

CONCLUSIONS

 Pneumococcal-NTHi cocolonization is associated with an elevated density of both species and with reduced diversity and increased fitness of pneumococcal serotypes. NTHi colonization may create a selective environment favoring pneumococci with immune-evasive phenotypes.

Necrotizing pneumonia and acute purulent pericarditis caused by Streptococcus pneumoniae serotype 19A in a healthy 4-year-old girl after one catch-up dose of 13-valent pneumococcal conjugate vaccine

Streptococcus pneumoniae is a common cause of infectious diseases in children that may lead to life-threatening complications. Acute purulent pericarditis is an uncommon complication of S. pneumoniae in the antibiotic era. A healthy 4-year-old girl was admitted with pneumonia and pleural effusion. She had received one catch-up dose of 13-valent pneumococcal conjugate vaccine at 2 years of age. She rapidly developed necrotizing pneumonia, complicated by bronchopleural fistula presenting as subcutaneous emphysema and pneumothorax and acute purulent pericarditis. S. pneumoniae serotype 19A was subsequently identified from blood, empyema and pericardial fluid cultures. After appropriate antibiotic therapy and a right lower lobectomy, her condition stabilized and she promptly recovered. This case highlights two rare potential clinical complications of pneumococcal disease in a child: necrotizing pneumonia and acute purulent pericarditis. This is the first report of a child who received just one catch-up dose of 13-valent pneumococcal conjugate vaccine at 2 years of age, as per the United States' Advisory Committee on Immunization Practice's recommendations, but who still developed severe invasive pneumococcal disease with life-threatening complications caused by S. pneumoniae serotype 19A.

Serotype distribution and penicillin-non-susceptibility of Streptococcus pneumoniae causing invasive diseases in Kuwait: A 10-year study of impact of pneumococcal conjugate vaccines

OBJECTIVES

The impact of PCV7 and PCV13 on pneumococcal infections in Kuwait is not known. Therefore we evaluated the impact on pneumococcal serotype distribution and penicillin-non-susceptibility in invasive infections in Kuwait.

METHODS

Children < 2 y were given PCV7 from Aug 2006 to Jul 2010 (period I), and PCV13 from Aug 2010 to Jul 2013 (period II) with a pre-vaccination period from Aug 2003 to Jul 2006. Serotype and penicillin-non-susceptibility of blood and cerebrospinal fluid isolates from all ages were determined.

RESULTS

In <2 y old children, even with a small number of infections, a drop in PCV7 serotypes was evident after vaccination. For all age groups combined, in the pre-vaccination period, PCV7, PCV13, PCV13 non-PCV7 serotypes and penicillin-non-susceptibility constituted 53.2%, 72.6%, 19.4% and 6.5% of the isolates respectively. PCV7, PCV13 non-PCV7 serotypes and penicillin-non-susceptibility changed to 32.7%, 28.2% and 7.3% (period I) and 6.6%, 22.2% and 8.9% (period II).

CONCLUSIONS

Vaccines reduced invasive infections due to PCV7 serotypes.

Predictive and prognostic factors in patients with blood-culture-positive community-acquired pneumococcal pneumonia

In patients with pneumococcal community-acquired pneumonia (CAP), the risk factors for bacteraemia and its impact on outcomes are not fully elucidated. We aimed to compare characteristics of patients with blood-culture-positive versus blood-culture-negative pneumococcal CAP, and to characterise bacteraemic serotypes.We describe a prospective, observational study on nonimmunocompromised patients with pneumococcal CAP, from 1996 to 2013. We define severe pneumonia according to American Thoracic Society/Infectious Diseases Society of America guidelines.Of a total of 917 patients with pneumococcal CAP, 362 had blood-culture-positive pneumococcal pneumonia (BCPPP; 39%). High C-reactive protein (CRP) (≥20 mg·dL(-1)) (odds ratio (OR) 2.36, 95% CI 1.45-3.85), pleural effusion (OR 2.03, 95% CI 1.13-3.65) and multilobar involvement (OR 1.69, 95% CI 1.02-2.79) were independently associated with bacteraemic CAP, while nursing home resident (OR 0.12, 95% CI 0.01-1.00) was found as a protective factor. Despite the clinical differences, BCPPP showed similar outcomes to blood-culture-negative pneumococcal pneumonia (BCNPP). 14% of the serotypes (period 2006-2013) causing bacteraemia are included in pneumococcal conjugate vaccine PVC7, 74% in pneumococcal conjugate vaccine PVC13 and 83% in pneumococcal polysaccharide vaccine PPSV23.Pleural effusion, a high level of CRP and multilobar involvement predicted an increased risk of BCPPP. Although BCPPP patients were more severely ill at admission, mortality was not significantly greater than in BCNPP patients.

Invasive disease potential of pneumococci before and after the 13-valent pneumococcal conjugate vaccine implementation in children

BACKGROUND

Changes in serotype distribution have been induced after pneumococcal conjugate vaccines (PCV) implementation, and non-vaccine serotypes are now circulating. Among these latter serotypes, we aimed to distinguish those with high invasive disease potential before (2008-2009) and after PCV13 implementation (2012-2013).

METHODS

Invasive pneumococcal disease (IPD) serotypes isolated from children 6 to 24 months were compared with nasopharyngeal-colonizing serotypes in healthy children. To assess the invasive potential of a given serotype, odds ratios (ORs) were calculated. For each serotype, OR >1 indicated increased probability of association with IPD and OR <1 decreased probability.

RESULTS

In 2008/2009 and 2012/2013, 355 pneumococci were isolated from 1212 healthy children and from 569 IPD, including 166 meningitis, 114 pneumonia, and 289 other IPDs. In period 1, serotypes 7F, 3, 1, 24F, and 19A showed highly significant invasive disease potential whereas in period 2, only serotype 24F was associated with a significant high OR (6.6 [95% CI 2.6; 16.2]). Of note, for serotype 12F, OR could not be calculated because of no carrier recorded, however, if there had been a single 12F carrier, the OR would be among the highest, in period 2, 15.7 [95% 3.4; 73.0]). Only two serotypes appeared negatively associated with IPD, 11A and 23B in the period 2 as compared with nine in period 1. In the second period, pneumococcal penicillin non-susceptible isolates were mostly represented by serotypes 19A, 15A, 19F, 35B and 24F both in carriers and IPD. Only one strain was resistant to penicillin with MIC=4 μg/ml (serotype 19A) during the first period.

CONCLUSION

In children <2 years old, compared to the previous period, the number of serotypes having a high disease potential decreased after PCV13 implementation, only two non-vaccine serotypes, 24F and 12F, had high invasive disease potential.

Noninvasive pneumococcal clones associated with antimicrobial nonsusceptibility isolated from children in the era of conjugate vaccines

Carriage and noninvasive pneumococcal isolates frequently have a higher prevalence of antimicrobial nonsusceptibility than invasive isolates. From 2009 to 2014, we determined the associated clones in 169 pediatric noninvasive nonsusceptible pneumococci from a total of 506 isolates collected after 7- and 13-valent conjugate vaccine introduction (PCV7/13) to the Irish childhood immunization schedule in 2008 and 2010, respectively. We compared our results to those from 25 noninvasive pediatric pneumococcal isolates collected in 2007, the year before introduction of conjugate vaccines. In 2007, England(14)-9 and Spain(9V)-3 accounted for 12% and 32% of nonsusceptible clones, respectively, but in 2009 to 2014, their prevalence fell to 0% and 2.4%. Furthermore, there was a significant decline in Spain(6B)-2 and its variants from 2009 to 2014 (P = 0.0024). Fluctuations occurred in clonal complex 320 associated with serotype 19A. The prevalence of Sweden(15A)-25 and its variants and ST558 (a single-locus variant of Utah(35B)-24) associated with nonvaccine serotypes (NVT) 15A and 35B increased from 0% and 8% in 2007 to 19% and 16% in 2013 to 2014, respectively. Pilus locus 1 (PI-1) is associated with the spread of some nonsusceptible pneumococcal clones. PI-1 was more frequently associated with PCV7/13 serotypes than NVT (P = 0.0020). Our data highlight the value of surveillance of noninvasive pneumococci following conjugate vaccine introduction. Importantly, emerging clones associated with NVT may limit the effectiveness of PCV7/13 in reducing the high rate of nonsusceptibility among pediatric noninvasive pneumococci, with implications for empirical treatment strategies.

Differential impact of pneumococcal conjugate vaccines on bacteremic pneumonia versus other invasive pneumococcal disease

BACKGROUND

Bacteremic pneumonia (BP) accounts for ~35% of invasive pneumococcal disease (IPD) in young children. Our aims were to compare age, seasonal and serotype distribution of BP versus non-BP IPD and to determine whether the impact of the sequential 7/13-valent pneumococcal conjugate vaccine (PCV7/PCV13) introduction on disease incidence differed between BP and non-BP IPD in children <5 years of age.

METHODS

A nationwide, prospective, population-based, active surveillance (July 2004-June 2013) was conducted. All IPD episodes were included. PCV7 was introduced to the Israeli National Immunization Plan in July 2009 and has been replaced by PCV13 since November 2010.

RESULTS

In all, 983 (36.8%) BP and 1687 (63.2%) non-BP IPD episodes were recorded. A higher proportion of BP than that of non-BP IPD episodes (42.0% vs. 20.7%; P < 0.001) occurred in children >24 months old. Seasonality differed between BP and non-BP IPD, with yearly earlier peaks of non-BP IPD. The proportion of the 5 additional PCV13 serotypes (1, 3, 5, 7F and 19A) was higher in children with BP versus non-BP IPD (39.6% vs. 23.6%; P < 0.01). Shortly after PCV7 introduction, non-BP IPD rate was significantly reduced but that of BP was not. However, PCV13 introduction resulted in rapid reduction of BP rate, with a further reduction of non-BP IPD.

CONCLUSION

The differences in age distribution, seasonality and serotype distribution between BP and non-BP IPD suggest that the pathogenesis of these 2 entities is not identical and resulted in different impact rate dynamics after PCV7 and PCV13 introduction.

Nasopharyngeal carriage of Streptococcus pneumoniae in Romanian children before the introduction of the pneumococcal conjugated vaccination into the national immunization programme: a national, multi-centre, cross-sectional observational study

OBJECTIVES

We analysed the distribution of vaccine and non-vaccine Streptococcus pneumoniae serotypes and the antimicrobial susceptibility of pneumococcal strains isolated from healthy Romanian children.

METHODS

A multi-centre cross-sectional study was performed in four counties to evaluate carried strains of S. pneumoniae isolated from 2000 children aged 0-5 years.

RESULTS

S. pneumoniae carriage was detected in 25.25% of the tested children. Carriage increased from 16.7% among infants to 29.4% in 3-5-year-old children (p<0.0001). The proportions of the serotypes included in pneumococcal conjugate vaccines PCV7, PCV10, and PCV13 among our isolates were 39.9%, 40.1%, and 58.7%, respectively. Erythromycin resistance was 72.5%, and it was significantly lower in non-vaccine serotypes compared with PCV13 serotypes: 57.3% versus 83.6% (p<10(-7)). Penicillin minimum inhibitory concentrations (MICs) >0.064mg/l were recorded in 71.6%, but the penicillin MIC was >2mg/l for only 8.4% of tested isolates.

CONCLUSIONS

In Romanian children, the majority of carried S. pneumoniae isolates are vaccine serotypes. The isolates with MICs defining macrolide resistance were very frequent, as well as the isolates with MICs defining penicillin resistance in the case of meningitis or penicillin dose-dependent susceptibility for other infections, mainly for the strains belonging to PCV13 serotypes. The implementation of PCV13 within the Romanian national immunization programme could reduce the circulation of these strains with higher macrolide and/or penicillin MICs.

PCV7-induced changes in pneumococcal carriage and invasive disease burden in Alaskan children

BACKGROUND

Changes in pneumococcal serotype-specific carriage and invasive pneumococcal disease (IPD) after the introduction of pneumococcal conjugate vaccine (PCV7) could inform serotype epidemiology patterns following the introduction of newer conjugate vaccines.

METHODS

We used data from statewide IPD surveillance and annual pneumococcal carriage studies in four regions of Alaska to calculate serotype-specific invasiveness ratios (IR; odds ratio of a carried serotype's likelihood to cause invasive disease compared to other serotypes) in children <5 years of age. We describe changes in carriage, disease burden, and invasiveness between two time periods, the pre-PCV7 period (1996-2000) and the late post-PCV7 period (2006-2009).

RESULTS

Incidence of IPD decreased from the pre- to post-vaccine period (95.7 vs. 57.2 cases per 100,000 children, P<0.001), with a 99% reduction in PCV7 disease. Carriage prevalence did not change between the two periods (49% vs. 50%), although PCV7 serotype carriage declined by 97%, and non-vaccine serotypes increased in prevalence. Alaska pre-vaccine IRs corresponded to pooled results from eight pre-vaccine comparator studies (Spearman's rho=0.44, P=0.002) and to the Alaska post-vaccine period (Spearman's rho=0.28, P=0.029). Relatively invasive serotypes (IR>1) caused 66% of IPD in both periods, although fewer serotypes with IR>1 remained in the post-vaccine (n=9) than the pre-vaccine period (n=13).

CONCLUSIONS

After PCV7 introduction, serotype IRs changed little, and four of the most invasive serotypes were nearly eliminated. If PCV13 use leads to a reduction of carriage and IPD for the 13 vaccine serotypes, the overall IPD rate should further decline.

NOTE

The findings and conclusions in this report are those of the author(s) and do not necessarily represent the official position of the Centers for Disease Control and Prevention.

Evolving role of 13-valent pneumococcal conjugate vaccine in clinical practice

Since the introduction of 7-valent pneumococcal conjugate vaccine (PCV7), PCVs with extended coverage have become available, and there is emerging global evidence that these vaccines, in particular PCV13, have further reduced rates of invasive pneumococcal disease compared with PCV7. The present article aims to address emerging topics related to PCV13 use in routine clinical practice; specifically: (1) the potential role of high-valent PCVs in reducing pneumococcal disease burden; (2) the impact of PCVs on nasopharyngeal carriage and how this may contribute to reductions in otitis media and pneumonia, as well as the prevalence of resistant pneumococcal strains; (3) new PCV13 indications and (4) importance of schedule adherence for PCV in the prevention of cases of vaccine serotype-specific invasive pneumococcal disease. The beneficial effects of PCVs in protecting individuals from a wide spectrum of pneumococcal diseases can be increased by improving the vaccine coverage and adhering to the recommended vaccination schedules. There is increasing evidence that PCV13 has reduced much of the post-PCV7 burden of pneumococcal diseases in the pediatric community, including reducing pneumococcal colonization and the incidence of invasive pneumococcal disease and mucosal diseases. This has also led to a reduction in antibiotic-resistant pneumococcal diseases. The role of PCV13 in clinical practice is evolving, with PCV13 now available for children and adolescents between the ages of 6 weeks and 17 years, thus ensuring that children in all age groups can be protected against vaccine-serotype pneumococcal diseases. Continued surveillance is warranted to monitor the impact of PCV13 on disease burden.

Non-invasive pneumococcal serotypes and antimicrobial susceptibilities in a paediatric hospital in the era of conjugate vaccines

To evaluate the effects of 7-valent pneumococcal conjugate vaccine (PCV7) introduction to the routine childhood immunisation schedule in 2008 and its replacement by PCV13 in 2010 in Ireland, we surveyed the serotypes and antimicrobial susceptibilities of 339 pneumococci associated with carriage and non-invasive infection (NII) in a Dublin paediatric hospital from 2009 to 2012. Furthermore, we compared the distribution of pneumococcal serotypes collected from 2009 to 2012 to 105 NII pneumococci isolated in 2007, the year before conjugate vaccine introduction. PCV7 serotypes declined from 2007 to 2012 as follows: carriage, 67-23% (p=0.0004); conjunctivitis, 58-0% (p<0.0001); non-bacteraemic lower respiratory tract infection, 50-19% (p=0.0363) and otitis media 54-27%. Notably, antimicrobial resistant (AMR) PCV7 serotypes showed a significant decrease by the end of the study period (i.e. 2012) (p<0.0001). Compared with 2007 the overall occurrence of serotype 19A increased from 1.9 to 10% in 2010 (p=0.0132) and to 15% in 2011 (p=0.0005). Importantly, serotype 19A declined significantly from 2011 levels to an overall prevalence of 4.8% in 2012 (p=0.0243). Most striking was the significant reduction of AMR 19A (p=0.0195). Conversely, increases were observed in non-vaccine type (NVT) pneumococci in 2009-2012, of which serotypes 11A (n=30), 15B/C (n=17), 22F (n=14), 35Bn=13), non-typeable pneumococci (n=13) and 23A (n=12) were the most prevalent. Moreover, an increase in NVT non-susceptible to at least one antimicrobial in 2009-2012 was noted, attributable to serotypes 35B (n=10) and 15A (n=7). In summary, this study has shown that PCV7 and PCV13 introduction has had a positive impact on their target serotypes and antimicrobial resistance amongst pneumococci within a paediatric hospital within a short time period. However, the increase in NVT prevalence highlights the need for continued surveillance.

Impact of preceding flu-like illness on the serotype distribution of pneumococcal pneumonia

BACKGROUND

Even though the pathogenicity and invasiveness of pneumococcus largely depend on capsular types, the impact of serotypes on post-viral pneumococcal pneumonia is unknown.

METHODS AND FINDINGS

This study was performed to evaluate the impact of capsular serotypes on the development of pneumococcal pneumonia after preceding respiratory viral infections. Patients with a diagnosis of pneumococcal pneumonia were identified. Pneumonia patients were divided into two groups (post-viral pneumococcal pneumonia versus primary pneumococcal pneumonia), and then their pneumococcal serotypes were compared. Nine hundred and nineteen patients with pneumococcal pneumonia were identified during the study period, including 327 (35.6%) cases with post-viral pneumococcal pneumonia and 592 (64.4%) cases with primary pneumococcal pneumonia. Overall, serotypes 3 and 19A were the most prevalent, followed by serotypes 19F, 6A, and 11A/11E. Although relatively uncommon (33 cases, 3.6%), infrequently colonizing invasive serotypes (4, 5, 7F/7A, 8, 9V/9A, 12F, and 18C) were significantly associated with preceding respiratory viral infections (69.7%, P<0.01). Multivariate analysis revealed several statistically significant risk factors for post-viral pneumococcal pneumonia: immunodeficiency (OR 1.66; 95% CI, 1.10-2.53), chronic lung diseases (OR 1.43; 95% CI, 1.09-1.93) and ICI serotypes (OR 4.66; 95% CI, 2.07-10.47).

CONCLUSIONS

Infrequently colonizing invasive serotypes would be more likely to cause pneumococcal pneumonia after preceding respiratory viral illness, particularly in patients with immunodeficiency or chronic lung diseases.

Clinical features and outcomes of serotype 19A invasive pneumococcal disease in Calgary, Alberta

The recent introduction of the seven-valent pneumococcal conjugate vaccine has led to changes in the proportion of disease caused by different serotypes. The serotypes targeted by the vaccine have been reduced, and Streptococcus pneumonia serotype 19A is now the most commonly isolated serotype causing invasive pneumococcal disease. This serotype has been associated with antibiotic resistance. The authors of this article conducted a review of cases of invasive pneumococcal disease diagnosed between 2000 and 2010 in Calgary, Alberta, to examine the disease course of serotype 19A invasive pneumococcal disease compared with other serotypes.

BACKGROUND

Streptoccocus pneumoniae serotype 19A (ST19A) became an important cause of invasive pneumococcal disease (IPD) after the introduction of the conjugate vaccine.

OBJECTIVE

To examine the severity and outcome of ST19A IPD compared with non-ST19A IPD.

METHODS

The Calgary Area Streptococcus pneumoniae Epidemiology Research (CASPER) study collects clinical and laboratory data on all IPD cases in Calgary, Alberta. Analysis was performed on data from 2000 to 2010 comparing ST19A and non-ST19A IPD cases. Adjusted linear and logistic regression models were used to examine outcomes of duration of appropriate intravenous antibiotic therapy and intensive care unit admission, respectively.

RESULTS

ST19A tended to cause disease in younger patients. ST19A isolates were more often multidrug resistant (19% versus 0.3%; P<0.001). Adjusted logistic regression showed no difference in intensive care unit admission between ST19A and non-ST19A IPD cases (OR 1.4 [95% CI 0.8 to 2.7]). An adjusted linear regression model showed patients <18 years of age with a diagnosis of bacteremia and no risk factors infected with ST19A were, on average, treated with antibiotics 1.4 times (95% CI 1.1 to 1.9) as long as patients with non-19A IPD and the same baseline characteristics.

DISCUSSION

ST19A IPD was associated with an increase in average time on antibiotics. Although many of the infecting strains of ST19A were within the threshold for susceptibility, they may be sufficiently resilient to require a longer duration of antibiotic therapy or higher dose to clear the infection.

CONCLUSIONS

ST19A is more common in younger individuals, is more antibiotic resistant and may require longer average treatment duration.

Can the success of pneumococcal conjugate vaccines for the prevention of pneumococcal diseases in children be extrapolated to adults?

Before conjugate pneumococcal vaccines (PCVs) were introduced it was estimated that Streptococcus pneumoniae caused 500,000 cases of pneumonia, 50,000 cases of bacteremia and 3000 cases of meningitis annually in the United States in both children and adults. After 10 years of routine use of the 7-valent pneumococcal conjugate vaccine (PCV7) the incidence of vaccine-type pneumococcal diseases (PDs) had significantly decreased in vaccinated children (direct effect) and unvaccinated subjects of all ages (indirect effect). Second generation, higher-valent PCVs, especially 13-valent (PCV13), routinely implemented since 2010, have reduced the incidence of PDs caused by the six additional non-PCV7 serotypes, in both vaccinated and unvaccinated subjects. The licence for this vaccine has recently been extended to include adults aged 18 to 49 in Europe. Although PCV13 has an indirect effect on IPD in adults, this will probably not achieve the same level of disease control in adults and the elderly (especially those at high risk) as that obtained in vaccinated children. As highlighted in this paper, differences exist between children and adults for PD manifestations (incidence, morbidity and mortality) and serotypes isolated in nasopharyngeal carriage and diseases, so benefits from adult vaccination must be considered in this light. PCV13 induces an immune response in adults that is non-inferior for all serotypes common with the 23-valent plain polysaccharide vaccine that is currently recommended for adults and even superior for many serotypes. Although there is no evidence that this immune response translates to clinical efficacy in adults as seen in children, the results from a randomised trial in The Netherlands, expected in 2014, should provide the missing evidence. This evidence and efficient surveillance systems should provide the necessary data, essential for policy makers in their decisions on adult pneumococcal vaccination policies.