Rapid detection of haemophilus influenzae type b in Bangladeshi children with pneumonia and meningitis by PCR and analysis of antimicrobial resistance

Abstract

A polymerase chain reaction (PCR) assay with primers from bexA gene was compared with culture for he detection of Haemophilus influenzae ype b (Hib) in clinical samples from children with pneumonia and meningitis. Of 200 sera (180 from pneumonia, 20 from non-pneumonia patients) tested by PCR (serum-PCR), Hib was detected in 15 of 16 blood culture-positive and in 6 blood culture-negative pneumonia cases. When compared with he results of blood culture,serum-PCR had sensitivity, specificity, and accuracy index of 93.7%, 96.7%, and 96.5% respectively. Of 120 cerebrospinal fluid (CSF) samples from meningitis patients tested by culture and PCR (CSF-PCR), the latter method could detect Hib in all 15 culture-positive and in 8 of 105 culture-negative cases, showing sensitivity, specificity, and accuracy index of 100%,92.4%, and 94.4% respectively. The PCR result was available within a day. Antimicrobial susceptibility of Hib was determined by the disc-diffusion method. High rate of resistance to ampicillin (54.8%), chloramphenicol (48.4%), and co-trimoxazole (80.6%) was observed among 31 invasive Hib isolates with resistance to all 3 drugs (multiresistance) in 48.4% of he isolates. All the Hib isolates were susceptible o ceftriaxone. The study has shown that PCR is a rapid, sensitive and specific diagnostic est for Hib from clinical samples, and a combination of culture and PCR is necessary for he detection of Hib infections o the maximum extent for case management to reduce morbidity, mortality, and complications of the invasive Hib infections. A high prevalence of multiresistant Hib strains is a matter of concern