Antimicrobial resistance patterns and serotype distribution of invasive Streptococcus pneumoniae isolates from children in Taiwan from 1999 to 2004

One year period of invasive pneumococcal disease in children from a tertiary care hospital in Turkey in the post-vaccine era

The incidence of invasive pneumococcal disease (IPD) has decreased after pneumococcal conjugate vaccine used; however, a breakthrough infection may still be seen after vaccination. In this study, eight pediatric inpatients and nine episodes with IPD in our center were included. Their age and gender, diagnoses, facilitating factors, the status of immunization and the antibiotic resistance of Pneumococci, serotypes of Pneumococci were noted. The isolates were subjected to disc susceptibility tests for penicillin, macrolides, and fluoroquinolones, according to the guidelines of the Clinical and Laboratory Standards Institute. Of the vaccinated seven cases, four of them (57.1%) developed IPD which their serogroups were in vaccine content. It was observed that all four cases in question had an underlying facilitating factor. Pneumococcal antibiotic susceptibility is also crucial. Three of nine isolates (33.4%) were resistant, and one isolate (11.2%) was intermediate susceptible to penicillin. Six of the nine isolates (66.7%) had macrolide resistance in our investigation. Invasive pneumococcal infections with serogroups that exist in pneumococcal conjugate vaccine content may occur in vaccinated individuals.

Evaluation of Modified Sequential Multiplex PCR for Streptococcus pneumoniae Serotyping

The aims of this study were to develop modified sequential multiplex PCR (SM-PCR) primer sets and to evaluate their ability and efficiency for serotype determination. We selected target serotypes for SM-PCR testing according to serotype prevalence as reported in Asian publications. The modified SM-PCR consisted of 6 groups of PCR reactions, and each reaction was performed using 5 primer pairs. We evaluated the efficiency and performance of this modified multiplex PCR using 378 pneumococcal strains by comparing the findings with the results of the Quellung reaction. A total of 30 primer pairs were used in a consecutive set of 6 reactions. All results were concordant with those of the Quellung reaction and there was no cross-reactivity to unintended serotypes. We could identify the final serotypes of 370 isolates (97.9%). The coverage rates of modified SM-PCR were 42.6%, 65.9%, and 79.4% in reactions1, 2, and 3, respectively. The modified SM-PCR showed acceptable performance for detecting pneumococcal serotypes and can serve as useful alternative to the Quellung reaction.

Laboratory surveillance of antimicrobial resistance and multidrug resistance among Streptococcus pneumoniae isolated in the Kinki region of Japan, 2001-2015

The 7-valent pneumococcal conjugate vaccine (PCV7) was introduced among children in Japan in 2010. There are no long-term multicenter surveillance studies of antimicrobial resistance in S. pneumoniae before and after the introduction of PCV7. Therefore, we examined chronological trends in antimicrobial resistance among 4534 strains of S. pneumoniae isolated from both children and adults in the Kinki region of Japan during 2001-2015. High-level penicillin and third-generation cephalosporin resistance in S. pneumoniae increased among both children and adults during the period before the introduction of PCV7 (2001-2010). Besides penicillin and cephalosporin, pneumococcal carbapenem and macrolide resistance increased among children. The rate of resistance to these antibiotics was higher among children than among adults. The introduction of PCV7 decreased the rate of non-susceptibility to β-lactam antibiotics and the rate of multidrug resistant S. pneumoniae among children, but not among adults.

Pneumococcal carriage and antibiotic susceptibility patterns from two cross-sectional colonization surveys among children aged <5 years prior to the introduction of 10-valent pneumococcal conjugate vaccine - Kenya, 2009-2010

Background

Pneumococci are spread by persons with nasopharyngeal colonization, a necessary precursor to invasive disease. Pneumococcal conjugate vaccines can prevent colonization with vaccine serotype strains. In 2011, Kenya became one of the first African countries to introduce the 10-valent pneumococcal conjugate vaccine (PCV10) into its national immunization program. Serial cross-sectional colonization surveys were conducted to assess baseline pneumococcal colonization, antibiotic resistance patterns, and factors associated with resistance.

Methods

Annual surveys were conducted in one urban and one rural site during 2009 and 2010 among children aged <5 years. To reflect differences in vaccine target population, recruitment was age-stratified in Kibera, whereas a simple random sample of children was drawn in Lwak. Nasopharyngeal swabs were collected from eligible children. Pneumococci were isolated and serotyped. Antibiotic susceptibility testing was performed using the 2009 isolates. Antibiotic nonsusceptibility was defined as intermediate susceptibility or resistance to ≥1 antibiotics (i.e., penicillin, chloramphenicol, levofloxacin, erythromycin, tetracycline, cotrimoxazole, and clindamycin); multidrug resistance (MDR) was defined as nonsusceptibility to ≥3 antibiotics. Weighted analysis was conducted when appropriate. Modified Poisson regression was used to calculate factors associated with antibiotic nonsusceptibility.

Results

Of 1,087 enrolled (Kibera: 740, Lwak: 347), 90.0% of these were colonized with pneumococci, and 37.3% were colonized with PCV10 serotypes. There were no differences by survey site or year. Of 657 (of 730; 90%) isolates tested for antibiotic susceptibility, nonsusceptibility to cotrimoxazole and penicillin was found in 98.6 and 81.9% of isolates, respectively. MDR was found in 15.9% of isolates and most often involved nonsusceptibility to cotrimoxazole and penicillin; 40.4% of MDR isolates were PCV10 serotypes. In the multivariable model, PCV10 serotypes were independently associated with penicillin nonsusceptibility (Prevalence Ratio: 1.2, 95% CI 1.1–1.3), but not with MDR.

Conclusions

Before PCV10 introduction, nearly all Kenyan children aged <5 years were colonized with pneumococci, and PCV10 serotype colonization was common. PCV10 serotypes were associated with penicillin nonsusceptibility. Given that colonization with PCV10 serotypes is associated with greater risk for invasive disease than colonization with other serotypes, successful PCV10 introduction in Kenya is likely to have a substantial impact in reducing vaccine-type pneumococcal disease and drug-resistant pneumococcal infection.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-2103-0) contains supplementary material, which is available to authorized users.

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.

Streptococcus pneumoniae non-susceptibility and outpatient antimicrobial prescribing rates at the Alaska Native Medical Center

Background

American Indian/Alaska Native (AI/AN) people suffer substantially higher rates of invasive pneumococcal disease (IPD) than the general US population. We evaluated antimicrobial prescribing data and their association with non-susceptibility in Streptococcus pneumoniae causing IPD in AI/AN people between 1992 and 2009.

Methods

Antimicrobial use data were gathered from the electronic patient management system and included all prescriptions dispensed to Alaska Native patients aged 5 years and older from outpatient pharmacies at the Alaska Native Medical Center (ANMC). Antimicrobial susceptibility data were gathered from pneumococcal isolates causing IPD among Anchorage Service Unit AI/AN residents aged 5 years and older. Data were restricted to serotypes not contained in the pneumococcal vaccine (PCV7).

Results

Over the study period, overall antimicrobial prescribing increased 59% (285/1,000 persons/year in 1992 to 454/1,000 persons per year in 2009, p<0.001). Trimethoprim/sulfamethoxazole prescribing increased (43/1,000 persons/year in 1992 to 108/1,000 persons/year in 2009, p<0.001) and non-susceptibility to trimethoprim/sulfamethoxazole in AI/AN patients ≥5 years of age increased in non-PCV7 serotypes (0–12%, p<0.05). Similarly, prescribing rates increased for macrolide antibiotics (46/1,000 persons/year in 1992 to 84/1,000 persons/year in 2009, p<0.05). We observed no statistically significant change over time in erythromycin non-susceptibility among non-PCV7 serotypes in AI/AN patients aged 5 years or greater (0–7%, p=0.087).

Conclusion

Antimicrobial prescribing patterns of some antibiotics in the AI/AN population corresponded to increased antimicrobial resistance in clinical isolates. This study highlights the on-going threat of antimicrobial resistance, the critical importance of judicious prescribing of antibiotics and the potential utility of prescribing data for addressing this issue.

Streptococcus pneumoniae from Palestinian nasopharyngeal carriers: serotype distribution and antimicrobial resistance

Infections of Streptococcus pneumoniae in children can be prevented by vaccination; left untreated, they cause high morbidity and fatalities. This study aimed at determining the nasopharyngeal carrier rates, serotype distribution and antimicrobial resistance patterns of S. pneumoniae in healthy Palestinian children under age two prior to the full introduction of the pneumococcal 7-valent conjugate vaccine (PCV7), which was originally introduced into Palestine in a pilot trial in September, 2010. In a cross sectional study, nasopharyngeal specimens were collected from 397 healthy children from different Palestinian districts between the beginning of November 2012 to the end of January 2013. Samples were inoculated into blood agar and suspected colonies were examined by amplifying the pneumococcal-specific autolysin gene using a real-time PCR. Serotypes were identified by a PCR that incorporated different sets of specific primers. Antimicrobial susceptibility was measured by disk diffusion and MIC methods. The resulting carrier rate of Streptococcus pneumoniae was 55.7% (221/397). The main serotypes were PCV7 serotypes 19F (12.2%), 23F (9.0%), 6B (8.6%) and 14 (4%) and PCV13 serotypes 6A (13.6%) and 19A (4.1%). Notably, serotype 6A, not included in the pilot trial (PCV7) vaccine, was the most prevalent. Resistance to more than two drugs was observed for bacteria from 34.1% of the children (72/211) while 22.3% (47/211) carried bacteria were susceptible to all tested antibiotics. All the isolates were sensitive to cefotaxime and vancomycin.

Any or all of these might impinge on the type and efficacy of the pneumococcal conjugate vaccines and antibiotics to be used for prevention and treatment of pneumococcal disease in the country.

Childhood invasive pneumococcal disease caused by non-7-valent pneumococcal vaccine (PCV7) serotypes under partial immunization in Taiwan

BACKGROUND/PURPOSE

Emerging non-7-valent pneumococcal conjugate vaccine (PCV7) serotypes have replaced PCV7 serotypes in childhood invasive pneumococcal disease (IPD). This study was designed to describe the IPD caused by non-PCV7 serotypes under partial PCV7 immunization in Taiwan.

METHODS

All children <18 years of age diagnosed with IPD at National Cheng Kung University Hospital from 1998 to 2010 were enrolled. Clinical and laboratory information was collected. Pneumococcal isolates were tested for antimicrobial susceptibility and interpreted using Clinical Laboratory Standard Institute guidelines (2008). Serotypes were determined using the capsular swelling method.

RESULTS

One hundred and five patients with IPD were identified, including 75 PCV7 and 30 non-PCV7 isolates. Pneumonia (63.3%) was the leading clinical manifestation of non-PCV7 IPDs and 78.9% of pneumonia cases were associated with necrotizing pneumonia or empyema. Children with non-PCV7 IPDs had longer febrile days, required longer intensive care unit stays, and had a higher C-reactive protein level than those with PCV7 IPDs (p < 0.05). Serotype 3 is the most common non-PCV7 serotype (46.7%) and possesses the highest potential for pulmonary complications (p < 0.05, odds ratio: 0.114; 95% confidence interval, 0.013 - 0.973).

CONCLUSION

The changing epidemiology of IPDs following the introduction of PCV7 has been noted. Expanded serotype coverage of the vaccine is warranted.

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.

Pneumococcal pneumonia complicating purulent pericarditis in a previously healthy girl: a rare yet possible fatal complication in the antibiotic era

Purulent pericarditis is an extremely rare complication of invasive Streptococcus pneumoniae infection among children in the antibiotic era, and its mortality remains high if left untreated. This report involves a 4½-year-old girl who presented to our emergency department with productive cough, shortness of breath, and left-sided chest pain with a diagnosis of pneumococcal pneumonia. She subsequently developed life-threatening conditions including bilateral empyema with respiratory failure, purulent pericarditis, and multiple organ failure leading to death. The case highlights that purulent pericarditis is a rare yet possible disorder complicating pneumococcal disease in the antibiotic era. The increase in strains resistant to penicillin should alert emergency physicians to the potential for reemergence of pneumococcal pericarditis in children.

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.

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.

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.

Host and microbiologic factors associated with mortality in Taiwanese children with invasive pneumococcal diseases, 2001 to 2006

We concurrently evaluated host- and organism-related factors in determining the outcomes of 160 invasive pneumococcal diseases episodes in 158 Taiwanese children during 2001 and 2006. Most (138/160, 86.2%) episodes occurred at age less than 60 months, and an underlying condition was present in 35 (22.2%) cases. Common disease syndromes included complicated pneumonia (29.4%), uncomplicated pneumonia (29.4%), occult bacteremia (17.5%), and meningitis (14.4%). Mortality (13/160, 8.1%) was associated with age less than 24 months, underlying conditions, meningitis, cytopenia, intensive care, and penicillin MIC >or=2 microg/mL in univariate analysis. Pneumococcal serotypes, genotypes, origin of infections, and discordant therapy did not influence the outcome. Multivariate analysis determined the presence of underlying conditions (adjusted odds ratio [OR], 30.5; 95% confidence interval [CI], 4.8-193.1) and penicillin MIC >or=2 microg/mL (adjusted OR, 8.1; 95% CI, 1.4-47.3), which are the independent predictors for fatality. This finding highlighted the importance of immunization of disadvantaged children, targeting drug-resistant pneumococci.

National survey of invasive pneumococcal diseases in Taiwan under partial PCV7 vaccination in 2007: emergence of serotype 19A with high invasive potential

We conducted an active, population-based laboratory surveillance study to evaluate the epidemiologic features of invasive pneumococcal disease (IPD) in Taiwan. Concurrently, nasopharyngeal colonization of Streptococcus pneumoniae was evaluated among 1128 healthy children aged <or=5 years. The overall incidence was highest among children aged 2-4 years (15.6/100,000). Serotype 19A, which had never been reported in Taiwan previously, caused a substantial fraction of the invasive diseases (OR, 9.6; 95% CI, 3.1-29.4) among children aged 2-4 years. Comparing serotype distributions of the isolates from nasopharyngeal colonization among children aged <or=5 years, serotypes 14 (OR, 17.3; 95% CI, 5.2-57.9) and 19A (OR, 14.9; 95% CI, 1.9-117) had the highest invasive potential. The study found that serotype 19A expanded in Taiwan, a country with a low 7-valent conjugate pneumococcal vaccine coverage. The 7-valent conjugate pneumococcal vaccines covered 73% of cases in children aged between 2 and 4 years, and 64.7% of cases in children aged <2 years. Among patients aged >or=65 years, the 23-valent pneumococcal polysaccharide vaccine covered 70.4% of cases. In the future, a broader pneumococcal vaccine is needed.

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.

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.

Multidrug-resistant Streptococcus pneumoniae infections: current and future therapeutic options

Antibacterial resistance in Streptococcus pneumoniae is increasing worldwide, affecting principally beta-lactams and macrolides (prevalence ranging between approximately 1% and 90% depending on the geographical area). Fluoroquinolone resistance has also started to emerge in countries with high level of antibacterial resistance and consumption. Of more concern, 40% of pneumococci display multi-drug resistant phenotypes, again with highly variable prevalence among countries. Infections caused by resistant pneumococci can still be treated using first-line antibacterials (beta-lactams), provided the dosage is optimised to cover less susceptible strains. Macrolides can no longer be used as monotherapy, but are combined with beta-lactams to cover intracellular bacteria. Ketolides could be an alternative, but toxicity issues have recently restricted the use of telithromycin in the US. The so-called respiratory fluoroquinolones offer the advantages of easy administration and a spectrum covering extracellular and intracellular pathogens. However, their broad spectrum raises questions regarding the global risk of resistance selection and their safety profile is far from optimal for wide use in the community. For multi-drug resistant pneumococci, ketolides and fluoroquinolones could be considered. A large number of drugs with activity against these multi-drug resistant strains (cephalosporins, carbapenems, glycopeptides, lipopeptides, ketolides, lincosamides, oxazolidinones, glycylcyclines, quinolones, deformylase inhibitors) are currently in development. Most of them are only new derivatives in existing classes, with improved intrinsic activity or lower susceptibility to resistance mechanisms. Except for the new fluoroquinolones, these agents are also primarily targeted towards methicillin-resistant Staphylococcus aureus infections; therefore, demonstration of their clinical efficacy in the management of pneumococcal infections is still awaited.