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

Nasal colonization by potential bacterial pathogens in healthy kindergarten children of Nepal: a prevalence study

INTRODUCTION

In low- and middle-income countries including Nepal, respiratory tract infection (RTI) is considered as one of the most prominent public health problems in children. Multiple carriage of respiratory pathogens is common in children, especially in preschoolers as they are easily transmitted through close contact and poor hygienic condition. Thus, this research is based on the study of prevalence, co-existence, associated factors and antibiogram of nasal isolates among healthy preschoolers.

METHODS

The study was conducted in four randomly selected kindergarten schools (two government run and two private run) of Bhaktapur Municipality. Out of a total 140 students, 136 eligible participants of age group 2-5 years old were involved in the study. Nasal swab was collected for the isolation of five target isolates (Staphylococcus aureus, Streptococcus pneumoniae, Moraxella catarrhalis, Haemophilus influenzae and Haemophilus parainfluenzae) and their antibiotic resistance determination.

RESULTS

Of 136 participants involved, 128 (94.5%) were positive for carriage of at least one of the target bacteria. The most common isolate was M. catarrhalis 62.5% (80/128) followed by S. aureus 43.0% (55/128). There was a significant difference in bacterial carriage with respect to type of school (p value<0.05, OR=0.50, CI=0.20-0.90). Regarding bacterial co-existence, the most common co-existence was of S. aureus and M. catarrhalis & S. pneumoniae and M. catarrhalis 48.8%. Multiple logistic regression analysis showed that S. aureus was negatively associated with S. pneumoniae, M. catarrhalis and H. influenzae and S. pneumoniae was positively associated with M. catarrhalis and H. influenzae. Multidrug resistance was seen in 63 isolates (29.4%).

CONCLUSIONS

Nepalese kindergarten children are at a high risk of respiratory tract infection by multidrug resistant bacteria.

Characterization of Streptococcus pneumoniae strains isolated from patients with meningitis before the introduction of pneumococcal conjugate vaccine in Serbia

Introduction: Pneumococcal meningitis is a serious disease which affects mostly children ≤ 2 years, adults ≥ 65 years and immunodeficient patients. The introduction of pneumococcal conjugate vaccine (PCV) into immunization programs worldwide has led to a significant decrease in the incidence of invasive pneumococcal disease, reduction of antibiotic resistance and changes in the distribution of pneumococcal serotypes. In 2018, PCV10 was introduced into the National Immunization Program in Serbia. Aim: The aim of this study was to analyze the serotype distribution and antibiotic susceptibility of pneumococcal strains isolated from meningitis cases in the pre-vaccinal period (2009-2018) in Serbia. Material and methods: Meningeal isolates were sent into the National Reference Laboratory for streptococci between January 2009 and December 2018 for serotyping and antimicrobial susceptibility testing (AST). Serotyping was performed by Quellung reaction, while AST was performed using disk diffusion method and E-test. Results: A total of 199 strains were analyzed and 32 different serotypes have been identified. Among the 55 (27.64%) strains from children ≤16 years, 17 different serotypes were detected of which 19F, 14, 6A, and 6B were the most common. Regarding the 144 (72.36%) adult isolates, 30 different serotypes were present, the most common being 3, 19F, 14, 23F, 6A and 6B. The coverage of pediatric serotypes was 61.82% for PCV10 and 78.18% for PCV13. Statistically significant number of isolates showed resistance to: penicillin (53.26%), erythromycin (45.73%), clindamycin (40.20%), trimethoprim-sulfamethoxazole (34.17%) and tetracycline (34.17%). The isolates from children were more resistant to beta-lactams and macrolides (p < 0.05). Conclusion: During the pre-vaccinal period in Serbia, vaccinal serotypes dominated over non-vaccinal serotypes. Resistance is intermediate to high in the dominant serotypes of children and low in the most common adult serotype 3. Taking into consideration the possible changes in the pneumococcal population in the future, continued monitoring of post-vaccine serotype and resistance trends are essential.

Results from the Survey of Antibiotic Resistance (SOAR) 2014-16 in Bulgaria, Romania, Serbia and Croatia

Objectives

To determine antibiotic susceptibility of isolates of Streptococcus pneumoniae (n = 573) and Haemophilus influenzae (n = 345) collected in 2014-16 from Bulgaria, Romania, Serbia and Croatia.

Methods

MICs were determined by CLSI broth microdilution and susceptibility was assessed using CLSI, EUCAST and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints.

Results

Among S. pneumoniae, susceptibility was generally lowest in Romania and Serbia and highest in Bulgaria. Rates of susceptibility to penicillin (CLSI oral or EUCAST) were 22.3% and 21.8% in Romania and Serbia respectively, 57% in Croatia and 86.6% in Bulgaria. Similarly, macrolide susceptibility using CLSI/EUCAST breakpoints was low in Romania and Serbia (∼28% and 34.5%, respectively), higher in Croatia (55.9%) and highest in Bulgaria (∼75%). Only fluoroquinolones were active against all isolates in all four countries. Susceptibility was higher and variability across countries less pronounced for H. influenzae. Susceptibility by CLSI criteria to amoxicillin/clavulanic acid, azithromycin, cefuroxime, ceftriaxone and fluoroquinolones was ≥98% in all countries. Ampicillin susceptibility ranged from 85.3% in Romania to 100% in Bulgaria. Much greater variability was seen across breakpoints. Susceptibility to azithromycin and cefuroxime using CLSI criteria was ≥98% in all four countries, but was 0%-1% by EUCAST criteria.

Conclusions

The variability in antimicrobial susceptibility using different breakpoints makes it difficult for clinicians to interpret antimicrobial resistance data, and efforts should be made to harmonize breakpoints. The variability found across the four neighbouring countries demonstrates the need to monitor and publish national and local resistance patterns. These findings provide information critical for the selection of appropriate antimicrobial agents for the treatment of S. pneumoniae and H. influenzae.

Diversity of Mosaic pbp2x Families in Penicillin-Resistant Streptococcus pneumoniae from Iran and Romania

Penicillin-resistant Streptococcus pneumoniae strains are found at high rates in Romania and Iran. The mosaic structure of PBP2x was investigated in 9 strains from Iran and in 15 strains from Romania to understand their evolutionary history. Mutations potentially important for β-lactam resistance were identified by comparison of the PBP2x sequences with the sequence of the related PBP2x of reference penicillin-sensitive S. mitis strains. Two main PBP2x mosaic gene families were recognized. Eight Iranian strains expressed PBP2x variants in group 1, which had a mosaic block highly related to PBP2x of the Spain^23F-1 clone, which is widespread among international penicillin-resistant S. pneumoniae clones. A second unique PBP2x group was observed in Romanian strains; furthermore, three PBP2x single mosaic variants were found. Sequence blocks of penicillin-sensitive strain S. mitis 658 were common among PBP2x variants from strains from both countries. Each PBP2x group contained specific signature mutations within the transpeptidase domain, documenting the existence of distinct mutational pathways for the development of penicillin resistance.

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.

Pneumococcal serotype distribution: A snapshot of recent data in pediatric and adult populations around the world

S. pneumoniae infection remains a serious public health concern despite the availability of vaccines covering up to 23 of more than 94 known serotypes. The purpose of the present study was to monitor recent serotype distribution data. PubMed, EMBASE, Cochrane Reviews and Ingenta databases were searched. Serotype data covering invasive pneumococcal disease (IPD) and non-IPD were extracted from articles published from March 2014 to March 2015. Fifty-nine studies presented pneumococcal serotype prevalence by specific age categories. Most prevalent serotypes not covered by pneumococcal conjugate vaccines (PCV) were as follows: 15B, 22F, 15A, 23A among children under the age of 7 y with IPD; among adults with IPD: 22F, 11A, 10A, 38 in the 65 y and older age group; 12F, 9N, 8 in the 50-64 year-old age group and 12F, 8, 6C, 16F in the 15-59 age group. Geographic variations in serotype distribution highlight the importance of monitoring evolving pneumococcal serotype prevalence after pneumococcal vaccine implementation.

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.