Serotype and antimicrobial resistance patterns of Streptococcus pneumoniae isolated from Taiwanese children: comparison of nasopharyngeal and clinical isolates

ΔA146Ply-HA stem protein immunization protects mice against influenza A virus infection and co-infection with Streptococcus pneumoniae

Influenza virus (IV) is a common pathogen affecting the upper respiratory tract, that causes various diseases. Secondary bacterial pneumonia is a common complication and a major cause of death in influenza patients. Streptococcus pneumoniae (S. pneumoniae) is the predominant co-infected bacteria in the pandemic, which colonizes healthy people but can cause diseases in immunocompromised individuals. Vaccination is a crucial strategy for avoiding infection, however, no universal influenza vaccine (UIV) that is resistant to multiple influenza viruses is available. Despite its limited immunogenicity, the hemagglutinin (HA) stem is a candidate peptide for UIV. ΔA146Ply (pneumolysin with a single deletion of A146) not only retains the Toll-like receptor 4 agonist effect but also is a potential vaccine adjuvant and a candidate protein for the S. pneumoniae vaccine. We constructed the fusion protein ΔA146Ply-HA stem and studied its immunoprotective effect in mice infection models. The results showed that intramuscular immunization of ΔA146Ply-HA stem without adjuvant could induce specific antibodies against HA stem and specific CD4+ T and CD8+ T cellular immunity in BALB/c and C57BL/6 mice, which could improve the survival rate of mice infected with IAV and co-infected with S. pneumoniae, but the protective effect on BALB/c mice was better than that on C57BL/6 mice. ΔA146Ply-HA stem serum antibody could protect BALB/c and C57BL/6 mice from IAV, and recognized HA polypeptides of H3N2, H5N1, H7N9, and H9N2 viruses. Moreover, ΔA146Ply-HA stem intramuscular immunization had a high safety profile with no obvious toxic side effects. The results indicated that coupling ΔA146Ply with influenza protein as a vaccine was a safe and effective strategy against the IV and secondary S. pneumoniae infection.

Relationship Between Serotypes and Antimicrobial Nonsusceptibility of Streptococcus pneumoniae Clinical Isolates in Tunisia

Streptococcus pneumoniae remains a significant cause of morbidity and mortality worldwide despite the overall success of the vaccine programs. In Tunisia, pneumococcal conjugate vaccines (PCV)10 was introduced in the national immunization program in April 2019. We sought to determine the relationship between serotypes and antimicrobial nonsusceptibility of S. pneumoniae isolates recovered from clinical samples in the prevaccination period in the south of Tunisia. A total of 504 nonduplicate S. pneumoniae isolates collected between 2012 and 2018 were tested for antimicrobial susceptibility, among them 439 (87.1%) were serotyped. The most common serotypes were 19F (17.8%), 14 (15.3%), 3 (9.1%), 19A (8.2%), and 23F (7.3%). The proportions of isolates with serotypes covered by PCV7, PCV10, and PCV13 were 55.4%, 56.3%, and 77.9%, respectively. Three-quarters (74.4%) of pneumococcal isolates were nonsusceptible to penicillin, and about half (54.8%) were multidrug resistant. Penicillin nonsusceptibility was observed for all 19A and 23F isolates, and was significantly associated with serotypes 19F (odds ratio [OR]: 33.7) and 14 (OR: 8.7). A significant association with multidrug resistance was noted for serotypes 19A (OR: 10), 19F (OR: 9.4), 23F (OR: 8.6), and 6B (OR: 5.2). The alarming rates of pneumococcal antimicrobial nonsusceptibility and the strong association with the most prevalent serotypes compel microbiologists to monitor the impact of the PCV10 introduced recently in our national immunization program.

Streptococcus pneumoniae Serotype Distribution and Pneumococcal Conjugate Vaccine Serotype Coverage among Pediatric Patients in East and Southeast Asia, 2000-2014: a Pooled Data Analysis

Pneumococcal infection is one of the leading causes of death worldwide, especially in children of developing and underdeveloped countries. Capsular polysaccharide-based vaccines are available for the prevention of this disease. A 7-valent pneumococcal conjugate vaccine (PCV7) was licensed in 2000 for use in children less than two years of age. Subsequently, to broaden the protection, 10-valent (PCV10) and 13-valent (PCV13) vaccines were licensed in 2009 and 2010, respectively. All of these conjugate vaccines elicit an immune response that only provides protection against the infection of S. pneumoniae serotypes included in the formulation. Profiles of S. pneumoniae serotype distribution and serotype coverage for both PCV7 and PCV13 have been reported in some Asian countries/territories. But the published results cannot provide conclusive information due to the difference in studied population and geographic areas. The goals of this review are to obtain an accurate estimate of serotype coverage for PCV7, PCV10, and PCV13 and examine the change in the S. pneumoniae serotype distribution after PCV7 use among pediatric patients in East and Southeast Asia through the analysis of pooled data that were published in the English literature between 2000 and 2014.

Pneumococcal disease and use of pneumococcal vaccines in Taiwan

The use of pneumococcal vaccine plays an important role for prevention of invasive pneumococcal disease (IPD). However, introducing the pneumococcal vaccine into the national immunization program (NIP) is complex and costly. The strategy of progressively integrating the pneumococcal conjugate vaccine (PCV) into the NIP in Taiwan provides valuable experience for policy makers. The 7-valent PCV (PCV7) was first available in Taiwan in late 2005. PCV7 was first provided free to children with underlying diseases, those in vulnerable socioeconomic status, and those with inadequate health care resources. The catch-up immunization program with the 13-valent PCV was launched in 2013 and the national pneumococcal immunization program was implemented in 2015. Children aged 2-5 years had the highest incidence of IPD among pediatric population in Taiwan. Although the incidence of IPD caused by PCV7 serotypes has declined, the overall incidence of IPD remained high in the context of PCV7 use in the private sector. A surge of IPD caused by serotype 19A occurred, accounting for 53.6% of IPD cases among children aged ≤ 5 years in 2011-2012. After the implementation of the national pneumococcal immunization program, serogroup 15 has become the leading serogroup for IPD in children. Continued surveillance is necessary to monitor the serotype epidemiology in Taiwan.

Pharmacotherapy for pneumococcal infections: an update

INTRODUCTION

The management of pneumococcal diseases still places a significant burden on medical and economic resources. The subjects at greatest risk of pneumococcal infections are children.

AREAS COVERED

The aim of this review is to analyse the best current therapeutic approach to pneumococcal resistance, taking into account the level of susceptibility of Streptococcus pneumoniae, and the pharmacokinetics and pharmacodynamics of different antibiotics in the various pneumococcal diseases.

EXPERT OPINION

Antibiotic treatment of a number of pneumococcal diseases remains difficult or impossible due to the presence of strains resistant to commonly used antibiotics. In children the problem is significantly more important than in adults due to the reduced number of licenced drugs for subjects in the first years of life. The new conjugate pneumococcal vaccines containing 10 (PCV10) and 13 serotypes (PCV13), which include most of the recently emerging strains, might reduce the incidence of pneumococcal infections and the circulation of resistant pathogens. However, it is likely that optimal results will only be reached after the development of effective vaccines based on conserved proteins that are capable of preventing all pneumococcal infections, regardless of the serotype of the causative organism.

Risk factors and pathogenic significance of bacteremic pneumonia in adult patients with community-acquired pneumococcal pneumonia

OBJECTIVE

This study was performed to identify risk factors for the development of bacteremic pneumonia and to evaluate the impact of bacteremia on the outcome of pneumococcal pneumonia.

METHODS

Using a database from a surveillance study of community-acquired pneumococcal pneumonia, we compared data of the bacteremic group with that of the non-bacteremic group.

RESULTS

Among 981 adult patients with pneumococcal pneumonia, 114 (11.6%) patients who had documented pneumococcal bacteremia were classified into the bacteremic group. In a multivariable analysis, use of immunosuppressant drugs, younger age (<65 years), and DM were independent risk factors associated with the development of bacteremic pneumonia among patients with pneumococcal pneumonia (all P < 0.05). The mortality rate was significantly higher in the bacteremic group than in the non-bacteremic group (28.6% vs. 8.5%; P < 0.001). The multivariable analysis revealed that concomitant bacteremia was one of the significant risk factors associated with mortality (OR, 2.57; 95% CI, 1.24-5.29), along with cerebrovascular disease and presentation with septic shock (all P < 0.05).

CONCLUSIONS

Bacteremia was a common finding in pneumococcal pneumonia and was associated with a higher mortality rate. Several clinical variables may be useful for predicting bacteremic pneumonia among patients with pneumococcal pneumonia.

Social-economic factors and irrational antibiotic use as reasons for antibiotic resistance of bacteria causing common childhood infections in primary healthcare

The most prevalent childhood bacterial infections in primary healthcare are respiratory, gastrointestinal and urogenital infections. The main aim of this paper was to consider factors (socio-economic factors and irrational antibiotic use) that contribute to the development of bacterial resistance, as well as measures that resulted in a reduction of this problem. Computerized search through the Medline of published articles on antibiotic resistance from 1996 to 2011 in English or Serbian was completed in August 2011. Combinations of used terms were antimicrobial/antibacterial/antibiotic and resistance/susceptibility in pediatric/children, and Streptococcus pneumoniae/Streptococci/Haemophilus influenzae/Salmonellae/Escherichia coli/Shigella/Staphylococcus aureus as well as antibiotics/antimicrobials/antibacterials and consumption/utilization/use. In many developing countries, antibiotic dispensing and its use in medicine, cattle breeding and agriculture are inadequately regulated, or existing laws are not being appropriately implemented. In addition, human travel contributes to antimicrobial drug resistance around the world. All of these factors have led to a very high level of bacterial resistance. On the contrary, in countries with a clearly defined and implemented legal framework concerning antibiotic prescribing, dispensing and utilization, the use of antibiotics is under constant surveillance. That resulted in a significantly lower antibacterial resistance. In conclusion, bacterial resistance could be reduced by the implementation of systemic and long-term measures at a country level as well as at all levels of healthcare. In order to reduce bacterial resistance, antibiotic use needs to be precisely regulated, and regulations should be coherent with practice. The international community must have a more active role in solving this global problem.

Immunogenicity and safety of a 13-valent pneumococcal conjugate vaccine given with routine pediatric vaccines in Taiwan

Immunogenicity and safety of 13-valent and 7-valent pneumococcal conjugate vaccines (PCV13; PCV7) were compared in Taiwanese children. In this double-blind, multicenter study, healthy children were randomly assigned to receive PCV13 (n=84) or PCV7 (n=84) at 2, 4, 6 and 15 months with routine pediatric vaccines. For the 7 PCV13/PCV7 common serotypes, serotype-specific immunoglobulin G (IgG) geometric mean concentrations (GMCs) were high 1 month postinfant series, with ≥95.0% in both groups achieving IgG levels ≥0.35 μg/mL, with a trend to lower IgG GMCs for PCV13 compared with PCV7 (PCV13:PCV7 GMC ratios 0.59-0.91). For the 6 additional serotypes unique to PCV13, GMCs were notably higher after PCV13 than PCV7 (PCV13:PCV7 GMC ratios 1.50-202.58). Immune responses generally increased posttoddler dose. Safety was similar between groups. PCV13 was safe and immunogenic in this Taiwanese population. PCV13 should offer broader protection than PCV7 against pneumococcal disease.

CLINICAL TRIALS REGISTRATION NUMBER

NCT00688870.

Nasopharyngeal carriage of Streptococcus pneumoniae in Taiwan before and after the introduction of a conjugate vaccine

BACKGROUND

The heptavalent pneumococcal conjugate vaccine was introduced in Taiwan in October 2005. To evaluate the effect of the vaccination, we conducted an active, prospective, large-scale, long-term, and multicenter study to assess the prevalence of nasopharyngeal Streptococcus pneumoniae carriage in Taiwanese children.

METHODS

This study was performed at three tertiary teaching hospitals in northern, central, and southern Taiwan. Questionnaires provided demographic, family/household, and medical history data. Pneumococcal isolates were tested for their susceptibility to various antimicrobial agents and serotypes. In addition, influenza virus and Staphylococcus aureus were recovered from nasopharyngeal and nasal swabs, respectively.

RESULTS

Between July 2005 and July 2008, 857 pneumococcal strains were recovered from a total of 6057 children aged >2 months to 5 years (carriage rate, 14.1%). Carriage rates differed geographically and varied with subject age. In a multivariate analysis, having at least one sibling, attendance at day-care centers, a history of otitis media, and history of upper respiratory tract infection in the previous 2 weeks were each associated with a higher risk of pneumococcal colonization of the nasopharynx. Staphylococcus aureus nasal colonization was inversely associated with nasopharyngeal carriage of pneumococcus (p=0.000; odds ratio [OR]: 0.48; 95% CI: 0.39-0.58). Daycare attendance was the only risk factor for carriage of penicillin non-susceptible S. pneumoniae (OR: 2.37; 95% CI: 1.22-4.88). Although vaccination rates rose from 2005 to 2008, no concomitant decrease in S. pneumoniae carriage occurred. The rate of penicillin resistance among S. pneumoniae isolates was 92.8% (using the meningitis criteria). The prevalence of cefotaxime resistance (21.6%) was higher than that of penicillin (6.9%; non-meningitis criteria). Slightly more than half (57.4%) of the isolates belonged to strains covered by the heptavalent pneumococcal conjugate vaccine when both vaccine and vaccine-related serotypes were included.

CONCLUSIONS

Although vaccination rates rose from 2005 to 2008, no concomitant decrease occurred in S. pneumoniae carriage. Interaction between S. aureus and S. pneumoniae may influence vaccination efficacy. These findings provide baseline data to further compare pneumococcal carriage rates and antibiotic resistance patterns in Taiwanese children as vaccination rates continue to increase.

Carriage and invasive isolates of Streptococcus pneumoniae in Caracas, Venezuela: the relative invasiveness of serotypes and vaccine coverage

The introduction of a pneumococcal conjugate vaccine in Venezuela needs previous studies to assess vaccine efficiency. We conducted a survey of nasopharyngeal pneumococcal carriage in urban children in Caracas and studied the distribution of serotypes. We compared these data with survey data available for invasive strains isolated in the same area and in the same time period. An overall pneumococcal carriage rate of 27% was observed. The most predominant capsular serotypes among carriage isolates were 6B (29%), 19A (13.8%), 23F (10%), 14 (8.3%), 6A (8.3%) and 15B/C (3.3%) and among invasive isolates 6B (25%), 14 (15%), and 19A, 6A, 7F, and 18 (7.5% each). The serotypes/groups 1, 5, 7F and 18, jointly covering 30% of the invasive strains, represented less than 0.7% of the carrier strains. The theoretical coverage of the pneumococcal conjugate vaccine PCV13 for carriage and invasive strains was calculated to be 74% and 90%, respectively. Our study demonstrates important differences for the serotype distribution in disease and carriage isolates and provides a key baseline for future studies addressing the prevalence and replacement of invasive and carriage serotypes after the introduction of the PCV 13 vaccine in Venezuela in the year 2010.

Global prevailing and emerging pediatric pneumococcal serotypes

Streptococcus pneumoniae is the leading cause of vaccine-preventable deaths among children younger than 5 years of age worldwide. The 7-valent pneumococcal conjugate vaccine (PCV7) is currently licensed in more than 90 countries and has contributed to significant declines in the incidence of invasive pneumococcal disease (IPD). Recent studies report an increased incidence of IPD caused by non-PCV7 vaccine serotypes (NVTs). Seroepidemiology of IPD caused by NVTs following the introduction of PCV7 is of interest, and this article provides a comprehensive global summary of the prevailing and emerging serotypes causing IPD in children. Currently, globally emerging or persistent NVTs include serotypes 1, 3, 5, 6A, 7F and 19A. Serotypes included in the recently licensed 10-valent pneumococcal Haemophilus influenzae protein D conjugate vaccine (PCV10) and 13-valent pneumococcal conjugate vaccine (PCV13) account for pneumococcal disease burdens in most developed countries of 65-85% and 80-90%, respectively. The seroprevalence of NVTs after widespread use of PCV10 and PCV13 requires ongoing monitoring.

Effects of myrcia ovata cambess. Essential oil on planktonic growth of gastrointestinal microorganisms and biofilm formation of enterococcus faecalis

The essential oil from the leaves of Myrcia ovata Cambess., commonly used in Brazil for the treatment of gastric illnesses, was screened for antimicrobial activity and action in the formation of microbial biofilms by Enterococcus faecalis. The oil was obtained by hydrodistillation using a clevenger-type system. Its chemical composition was analyzed using GC and GC-MS. Both MIC and MBC of the essential oil were determined by broth microdilution techniques and agar dilution method. The essential oil showed antimicrobial activity against E. faecalis, Escherichia coli, Pseudomonas aeruginosa, Salmonella choleraesuis, Staphylococcus aureus, Streptococcus pneumoniae and Candida parapsilosis. The results showed that the essential oil of M. ovata Cambess. was effective against the formation of biofilm by E. faecalis when compared with the control. Four volatile compounds, representing 92.1 % of the oil, were identified and geranial was the major component (50.4 %). At the best of our knowledge, this is the first report of the chemical composition and antimicrobial activity of the essential oil from leaves of M. ovata.

Summary of invasive pneumococcal disease burden among children in the Asia-Pacific region

Invasive pneumococcal disease (IPD) burden is significant in the Asia-Pacific region. This review describes the epidemiology and Streptococcus pneumoniae (SP) serotype distribution of IPD in children in the Asia-Pacific region from studies published from 1999 to 2010. IPD incidence varies widely in Asia-Pacific countries depending on the method of surveillance, the population studied, and the time period. Incidences are highest for younger children, with rates near 100-200 cases per 100,000 children aged <1 or 2 years. Incidences of preventable disease are estimated to be 6-200 cases per 100,000. Heptavalent pneumococcal conjugate vaccine (PCV7) serotype coverage shows a very wide range over the Asia-Pacific region. Ten countries have high vaccine serotype coverage (>70%), and six countries have low vaccine serotype coverage (<50%). The majority of SP serotypes in children with IPD in most countries in the Asia-Pacific region are susceptible to penicillin (intermediate and resistant <50%); a few countries have SP serotypes with high level resistance to penicillin (intermediate and resistant >50%). Japan, Taiwan, and Thailand have high PCV7 serotype coverage. Countries with low pneumococcal resistance to antimicrobials have shown increasingly higher nonsusceptibility with time. National vaccination programmes that include PCV7, 10-valent pneumococcal conjugate vaccine (PCV), or 13-valent PCV would significantly affect IPD burden in children aged <5 years in the Asia-Pacific region, as well as the burden of penicillin-nonsusceptible IPD.

Immunization with a combination of three pneumococcal proteins confers additive and broad protection against Streptococcus pneumoniae Infections in Mice

Pneumococcal polysaccharide-based vaccines are effective in preventing pneumococcus infection; however, some drawbacks preclude their widespread use in developing and undeveloped countries. Here, we evaluated the protective effects of ATP-dependent caseinolytic protease (ClpP), pneumolysin mutant (DeltaA146 Ply), putative lipoate-protein ligase (Lpl), or combinations thereof against pneumococcal infections in mice. Vaccinated mice were intraperitoneally and/or intranasally challenged with different pneumococcal strains. In intraperitoneal challenge models with pneumococcal strain D39 (serotype 2), the most striking protection was obtained with the combination of the three antigens. Similarly, with the intranasal challenge models, (i) additive clearance of bacteria in lungs was observed for the combination of the three antigens and (ii) a combination vaccine conferred complete protection against intranasal infections of three of the four most common pneumococcal strains (serotypes 14, 19F, and 23F) and 80% protection for pneumococcal strain 6B. Even so, immunity to this combination could confer protection against pneumococcal infection with a mixture of four serotypes. Our results showed that the combination vaccine was as effective as the currently used vaccines (PCV7 and PPV23). These results indicate that system immunization with the combination of pneumococcal antigens could provide an additive and broad protection against Streptococcus pneumoniae in pneumonia and sepsis infection models.

An unusual pneumococcal sequence type is the predominant cause of serotype 3 invasive disease in South Africa

We reviewed pneumococcal serotype 3 cases reported from 2000 through 2005 to a laboratory-based surveillance system for invasive pneumococcal disease in South Africa. The prevalence of serotype 3 invasive isolates was compared to their prevalence in carriage isolates to determine the odds of invasiveness due to serotype 3 among South African children. Three groups of serotype 3 strains were characterized by pulsed-field gel electrophoresis (PFGE) or Box element PCR (BOX-PCR), randomly selected invasive isolates from one province, isolates from a carriage study involving children in the same province, and antimicrobial-resistant invasive isolates collected nationally. Examples of the PFGE types identified were further characterized by multilocus sequence typing. In total, 15,980 viable isolates causing invasive disease were submitted, of which 661 (4%) were serotype 3, mostly from adults (85% [489/575]). Fewer serotype 3 isolates were nonsusceptible to antimicrobial agents tested (40/661 [6%]) than non-serotype 3 isolates (8,480/15,319 [55%]) (P < 0.001). Compared to non-serotype 3 cases, there was no association with HIV coinfection (2,212/2,569 [86%] versus 72/78 [92%]; P = 0.1) or increased case fatality ratio (1,190/4,211 [28%] versus 54/154 [35%]; P = 0.7). Serotype 3 in children had a low but statistically insignificant invasive disease potential (odds ratio [OR] of 0.15; 95% confidence interval [CI] of 0.01 to 1.06). Strains were grouped into 3 PFGE clusters, with the largest, cluster A, representing 54% (84/155), including 14 isolates confirmed as sequence type 458 (ST458). It was confirmed that 3 isolates from cluster B, which represented only 12% (18/155) of the isolates, were the serotype 3 global strain, ST180. We have therefore identified ST458 as predominating in South Africa, but with an invasive potential similar to that of the predominant global clone ST180.

Characterization of invasive isolates of Streptococcus pneumoniae among Taiwanese children

Accurate molecular surveillance is important in monitoring the dynamics of Streptococcus pneumoniae. A prospective study was conducted to collect invasive isolates of S. pneumoniae from children for genetic analysis from January 2004 to December 2006 in Taiwan. PCRs were performed to detect the zmpC and zmpD genes, both encoding a metalloprotease virulence factor in pneumococci, among these invasive isolates. During the study period, 68 invasive isolates of S. pneumoniae were obtained for analysis. Serotype 14 was the most common type isolated from children with invasive disease and was significantly associated with pneumonia (OR 3.1; 95% CI] 1.1-8.8; p 0.035). Serotype 23F was significantly associated with bacteraemia (OR 7.5; 95% CI 1.8-31.3; p 0.006). The seven-valent conjugate vaccine covered 83.8% of invasive isolates, but non-vaccine serotypes were more frequently isolated from patients with underlying diseases than from patients without underlying diseases (p 0.007 by Fisher's exact test). Clonal complexes related to international clones Spain23F ST81, Spain6B ST95, England14 ST9, Taiwan19F ST236, Taiwan23F ST242 and Colombia23F ST338 accounted for 52.9% of invasive isolates. Dissemination of the penicillin-resistant clones ST876, ST46, ST76 and ST2889, which were first identified in Taiwan, was also found; 1.5% of these invasive isolates carried the zmpC gene, and 47.1% of these invasive isolates carried the zmpD gene. In conclusion, the spread of certain international clones and some domestic antibiotic-resistant clones resulted in invasive diseases among Taiwanese children.

Genome evolution driven by host adaptations results in a more virulent and antimicrobial-resistant Streptococcus pneumoniae serotype 14

Background

Streptococcus pneumoniae serotype 14 is one of the most common pneumococcal serotypes that cause invasive pneumococcal diseases worldwide. Serotype 14 often expresses resistance to a variety of antimicrobial agents, resulting in difficulties in treatment. To gain insight into the evolution of virulence and antimicrobial resistance traits in S. pneumoniae from the genome level, we sequenced the entire genome of a serotype 14 isolate (CGSP14), and carried out comprehensive comparison with other pneumococcal genomes. Multiple serotype 14 clinical isolates were also genotyped by multilocus sequence typing (MLST).

Results

Comparative genomic analysis revealed that the CGSP14 acquired a number of new genes by horizontal gene transfer (HGT), most of which were associated with virulence and antimicrobial resistance and clustered in mobile genetic elements. The most remarkable feature is the acquisition of two conjugative transposons and one resistance island encoding eight resistance genes. Results of MLST suggested that the major driving force for the genome evolution is the environmental drug pressure.

Conclusion

The genome sequence of S. pneumoniae serotype 14 shows a bacterium with rapid adaptations to its lifecycle in human community. These include a versatile genome content, with a wide range of mobile elements, and chromosomal rearrangement; the latter re-balanced the genome after events of HGT.

Establishment of a young mouse model and identification of an allelic variation of zmpB in complicated pneumonia caused by Streptococcus pneumoniae

OBJECTIVE

Complicated pneumonia, including necrotizing pneumonia, lung abscess, and empyema, caused by Streptococcus pneumoniae in children has been increasing. We thus determined to investigate its virulence in an animal model and to identify virulence factors of S. pneumoniae.

DESIGN

Prospective, randomized, controlled animal study.

SETTING

University medical laboratory.

SUBJECTS

Male Balb/c-strain mice, 3 wks old.

INTERVENTIONS

We used a young mouse model to monitor bacterial virulence and a microarray to compare gene expression between S. pneumoniae from children with complicated and noncomplicated pneumonia. Deletion and complementation of a candidate gene were performed to study its role on the virulence of S. pneumoniae.

MEASUREMENTS AND MAIN RESULTS

A model of complicated pneumonia in young mice infected with strains of S. pneumoniae from children with complicated pneumonia was established. Using a microarray analysis, differences in zinc metalloprotease B (zmpB) RNA hybridization between two strains from children with complicated pneumonia (NTUH-p28 and NTUH-p15) and a strain (NTUH-p3) from a child with pneumococcal lobar pneumonia were found. Confirmatory assays revealed the signal differences were due to sequence variation in the zmpB gene. Infection with the zmpB deletion mutant of NTUH-p15 showed a significant decrease in the severity of pneumonia and no destructive lung injury. The zmpB complementation strain of NTUH-p15 significantly restored the level of inflammation and caused lung necrosis. For studying the effect of allelic variation of zmpB on the virulence of S. pneumoniae, we added zmpB of NTUH-p15 in the zmpB deletion mutant of NTUH-p3, which resulted in a higher bacterial burden than that in wild-type NTUH-p3.

CONCLUSIONS

A young mouse model is established for complicated pneumococcal pneumonia. This model proved that allelic variation of zmpB affects the virulence of S. pneumoniae.

Clonal spread of highly beta-lactam-resistant Streptococcus pneumoniae isolates in Taiwan

This study aimed to evaluate the antimicrobial susceptibility profiles of 364 Streptococcus pneumoniae isolates and studied the genotypes of S. pneumoniae with high level beta-lactam resistance in Taiwan. Clonal complexes related to Spain(23F)-1, Taiwan(19F)-14, and Taiwan(23F)-15 were responsible for the spread of isolates with high beta-lactam resistance.

Serotype distribution and antimicrobial resistance patterns of Streptococcus pneumoniae isolated from children in China younger than 5 years

This study examined the epidemiology, antibiotic susceptibility, and serotype distribution of Streptococcus pneumoniae associated with invasive and noninvasive pneumococcal disease in children in China. A total of 451 clinical isolates from children (age, <5 years) were collected from 8 cities from January 2005 to December 2006, including 31 isolated from invasive disease. In vitro susceptibility to 14 antimicrobial agents was determined by the agar dilution method. Among all isolates tested, 64.3% were resistant to penicillin, and for invasive isolates, the resistance rate was 55.2%. Isolates from Wuhan and Nanjing showed the highest prevalence of penicillin resistance (89.6% and 85%), followed by those from Shenzhen (72.4%) and Chengdu (56.7%). Multidrug resistance rates to tetracycline, erythromycin, and clindamycin reached 90%. The 6 most common serotypes were 19F, 19A, 14, 6B, 23F, and 15. These accounted for 80.7% of the isolates. Resistance to penicillin varied among the 6 leading serotypes, ranging from 20% in serotype 15 to 87.3% in serotype 19F. Each of the 8 cities had different serotype distribution. The potential coverage by 7-, 10-, and 13-valent pneumococcal conjugate vaccine were 63.6%, 64.8%, and 79.6%, respectively.

Antimicrobial-resistant pathogens: an emerging pediatric threat

The clinical impact of these three bacterial threats is readily apparent to any who practice pediatrics. The potential virulence of CA-MRSA and MDR pneumococci and the threat of failed antimicrobial options for MDRGN pose enormous challenges now and in the near future. With careful attention to antimicrobial stewardship, however, and knowledge of the clinical and epidemiologic factors of these organisms, one can hope to mitigate the impact on patient care and outcomes while awaiting ongoing discovery of new antimicrobial options. Most important, however, will be careful and thoughtful management of any new antimicrobial products to protect their efficacy for the future.

Serotype distribution and antimicrobial susceptibilities of nasopharyngeal isolates of Streptococcus pneumoniae from children hospitalized for acute respiratory illnesses in Hong Kong

Five hundred nineteen Streptococcus pneumoniae isolates from nasopharyngeal aspirates of 3,157 children (age, <16 years) participating in a respiratory surveillance study in Hong Kong in 2005 and 2006 indicated that 64.9% and 37.2% of the isolates were not susceptible to penicillin and cefotaxime, respectively. The rate of potential coverage by the seven-valent conjugate vaccine was 72.3%, and the rate increased to 74.6% for serogroup-specific types.