Vo Thi Trang Dai, Viet Nam

Pasteur Institute of Ho Chi Minh City Microbiology and Immunology

Author Of 4 Presentations

CHARACTERIZATION OF STREPTOCOCCUS PNEUMONIAE FROM INVASIVE PNEUMOCOCCAL DISEASES IN SOUTH VIETNAM, 2008-2018 (ID 1009)

Abstract

Background

Streptococcus pneumoniae is a major cause of meningitis in children under 5 years in Vietnam, yet few data exist on the molecular characteristics of invasive pneumococcal disease (IPD) isolates in our region. This work presents characterization of IPD isolates in south Vietnam by Multilocus Sequence Typing (MLST).

Methods

Forty-three pneumococcal isolates from cases of meningitis (n=36) or sepsis (n=7) in children under five-years of age from 2008-2018 in Vietnam were serotyped by realtime PCR (for a possible 21 serotypes), subject to MLST and analyzed by goeBURST v1.2.1

Results

MLST analysis on 35 isolates to date identified 24 STs. goeBURST analysis identified 12 Clonal Complexes (CC) and 6 singletons. 74% (n=26) of isolates belonged to CCs related to PMEN clones and other multidrug-resistant (MDR) strains. Common CCs were CC90 (Spain6B-2) and CC236 (Taiwan19F-14) with 6 isolates each, followed by CC320/271 and CC63 (Sweden15A-25) with 5 and 4 isolates, respectively. Serotypes 6A/B, 14, and 19F were common and these belonged to 6, 4, 3 difference CCs, respectively.

Conclusions

There was a high diversity of pneumococcal clones associated with meningitis and sepsis in young children in south Vietnam. Most of the isolates belonged to PMEN clones or MDR strains.

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BACTERIAL MENINGITIS SURVEILLANCE OF CHILDREN UNDER 5 YEARS OF AGE IN SOUTHERN – VIET NAM, 2018-2019 (ID 313)

Abstract

Background

In Vietnam, the Invasive Bacterial Vaccine Preventable Diseases (IB-VPD) Surveillance network of World Health Organization which identifies major pathogens causing bacterial meningitis has been implemented since 2012. This program utilizes realtime PCR for detection of Streptococcus pneumoniae (Spn), Neisseria meningitidis (Nm) and Haemophilus influenzae (Hi) in children under 5 years of age suspected for bacterial meningitis. This work presents the positive rate and serotypes distribution of Spn from this program between 2018 and 2019.

Methods

540 cerebrospinal fluid (CSF) specimens of probable bacterial meningitis cases from 1 month to 59 months old were collected for identification of Spn, Nm and Hi by triplex direct rt-PCR. Positive samples for Spn were serotyped for 21 serotypes.

Results

Total positivity rate of three pathogens was 6.5%, among which Spn was predominant (94.3%, n= 33), following by Nm (5.7%, n=2), and there was no Hi detected. PCV13-types account for 94.0%, of which 6A/B was the most prevalent serotype (54.5%, n=18).

Conclusions

Spn was the most common cause of pediatric bacterial meningitis in Southern Vietnam from 2018-2019. Majority of serotypes found are included in pneumococcal conjugate vaccines, which are not yet introduced in the national immunization schedule in Vietnam.

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IMMUNOGENICITY OF A SINGLE DOSE OF PCV10 OR PCV13 AT 2 MONTHS OF AGE IN VIETNAM (ID 1007)

Abstract

Background

A 1+1 pneumococcal conjugate vaccine (PCV) schedule would increase its affordability for low and middle-income countries. The Vietnam Pneumococcal Trial II includes infants randomised to receive a 1+1 schedule of PCV10 or PCV13 at 2 and 12 months of age. This study measured the immunogenicity of a single dose of either PCV given at 2 months of age.

Methods

Serotype-specific IgG was measured at 3 and 12 months of age in PCV-vaccinated and unvaccinated controls using a WHO ELISA method.

Results

At 3 months, both vaccinated groups had higher antibody levels than controls for 7/10 serotypes (all except 6B, 14, 23F). The PCV10 group had higher antibody levels than the PCV13 group for 5/10 serotypes. Similar results were seen at 12 months, with higher antibody levels for all serotypes in the PCV10 group and 8/10 serotypes (all except 6V, 23F) in the PCV13 group compared with controls and higher antibody levels in the PCV10 than the PCV13 group for 7/10 serotypes.

Conclusions

A single dose of PCV in infancy is immunogenic and likely to provide some direct protection until the time of the booster dose. There may be a difference in the degree of protection offered by different PCVs.

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