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[Accuracy of the slide agglutination method evaluated with PCR in typing Haemophilus influenzae isolates]
Marylin Hidalgo1, Claudia Parra, María Victoria Ovalle
1Grupo de Microbiología, Instituto Nacional de Salud, Bogotá, D.C., Colombia.
Insights
The Haemophilus influenzae type b conjugate vaccine significantly reduced meningitis cases in Colombia. A study confirmed the slide agglutination method is accurate for serotyping H. influenzae when using strict quality control.
Area of Science:
- Microbiology
- Immunology
- Public Health
Background:
- Colombia implemented a vaccination program against Haemophilus influenzae type b (Hib) in 1998 for infants.
- A subsequent 40% decrease in Hib meningitis cases was observed, attributed to the vaccine.
- The national surveillance program relies on slide agglutination for H. influenzae serotyping.
Purpose of the Study:
- To validate the accuracy of the slide agglutination technique for H. influenzae serotyping.
- To compare slide agglutination results with Polymerase Chain Reaction (PCR) confirmation.
Main Methods:
- 146 H. influenzae isolates from children under five (1999-2002) were analyzed.
- Isolates were characterized by biochemical tests and serotyped using slide agglutination.
- PCR was employed to confirm the serotypes identified by slide agglutination.
Main Results:
- PCR confirmed 93% of H. influenzae serotype b identifications.
- PCR confirmed 92% of other H. influenzae serotypes.
- The slide agglutination method demonstrated high accuracy under strict quality control.
Conclusions:
- The slide agglutination technique is a reliable and accurate method for serotyping H. influenzae in public health surveillance.
- Maintaining strict quality control is crucial for the sensitivity and specificity of the slide agglutination method.
- The findings support the continued use of slide agglutination in monitoring the impact of Hib vaccination programs.
Abstract:
In 1998, the Colombian government initiated an immunization program for children under one year of age with a Haemophilus influenzae capsular type b conjugate vaccine. After two years, the surveillance program of the Colombian Instituto Nacional de Salud Microbiology Group reported a 40% decrease in meningitis cases caused by H. influenzae. This effect was attributed to the vaccination. The surveillance program uses the standardized slide agglutination technique to serotype H. influenzae. The current study validated the accuracy of the slide agglutination method by means of the PCR technique. From children under five years of age, 146 isolates were obtained. These were collected between 1999 and 2002, and were characterized by biochemical tests and serotyped by the INS as part of the surveillance program. PCR confirmed 93% of the H. influenzae serotype b and 92% of the other serotypes. When the slide agglutination technique is conducted under a strict quality control program, it remains a sensitive and specific tool for serotyping H. influenzae.