Summary auto-generated
This study characterized 120 Haemophilus influenzae isolates from North India using molecular typing methods to understand the genetic diversity of strains circulating in the community. Samples were collected from patients with meningitis, bacteremia, and chronic bronchitis, as well as healthy carriers. Results showed that 64% of isolates were serotype b and 36% were non-typable. Biotype I was most common among serotype b strains, while biotype II predominated in non-typable isolates. Three molecular techniques were employed: biotyping, ribotyping with restriction enzymes HaeIII and EcoRI, and RAPD-PCR fingerprinting using primers AP1 and AP2. RAPD fingerprinting with primer AP2 proved most discriminatory with a discrimination index of 0.925, successfully differentiating both serotype b and non-typable isolates. Isolates from disease samples showed concordant profiles across typing methods, while those from healthy carriers displayed random subtype distribution. This represents the first molecular subtyping study of H. influenzae strains from India, providing baseline data on the genetic polymorphism of this important pathogen in the Indian population.
Key findings
- Serotype b represented 64% of isolates (77/120) with biotype I predominant, while 36% were non-typable with biotype II most common
- RAPD-PCR fingerprinting with primer AP2 provided the highest discrimination index (0.925) compared to biotyping (0.731) and ribotyping methods
- Isolates from clinical specimens (blood, CSF, sputum) showed concordant profiles across all four genotyping methods, while isolates from healthy carriers displayed random subtype distribution
- High prevalence of H. influenzae meningitis in North India, with 24% of CSF samples and 10% of blood samples testing positive for serotype b
This summary was generated automatically from the article PDF and is not part of the original publication. Refer to the PDF for the authoritative text.
Abstract
A total of 120 Haemophilus influenzae isolates from blood, cerebrospinal fluid, sputum and throat swabs of patients and carriers in North India was characterised by biotyping, ribotyping and random amplification of polymorphic DNA (RAPD)-PCR. Of these, 77 isolates (64%) were serotype b; the other 43 (36%) were non-typable. Biotype I was the most predominant among the typable strains and biotype II among the non-typable strains. Ribotyping with restriction endonucleases HaeIII and EcoRI differentiated the isolates into three and six ribotypes, respectively. However, RAPD fingerprints generated by the application of arbitrary primers AP1 and AP2 provided a higher level of discrimination. RAPD typing revealed distinct polymorphism among the serologically typable isolates. This study is the first report that stratifies the subtypes of H. influenzae strains from India by molecular techniques.