<em>Haemophilus influenzae</em> type b pneumonia in Egyptian children under five years: A step toward the identification of the real burden in our community by the use of real-time polymerase chain reaction

Abstract

Haemophilus influenzae (Hi) causes more than 3 million cases of serious disease, mainly meningitis and pneumonia in children less than 5 years old with approximately 386,000 deaths each year worldwide. The presence or absence of a polysaccharide capsule is an important distinguishing characteristic of H. influenzae species. The polysaccharide capsule can be serologically classified into six serotypes (a to f). Invasive Hi diseases in children were almost exclusively caused by serotype b (Hib). To the best of our knowledge, the real burden of Hib pneumonia in Egypt is not clarified. Yet, few studies are published and concerned with Hib sepsis among neonates or Hib meningitis in children. We aimed in this study to identify the frequency of Hib pneumonia among Egyptian children below five years by the use of real-time polymerase chain reaction (PCR) technique, with insight on antimicrobial resistance of Hib strains in the Egyptian community. One hundred patients with community-acquired pneumonia were investigated for Hib by both real-time PCR and bacterial culture. Haemophilus influenzae type b was diagnosed in 31% of the examined population by PCR, with sensitivity of 100% (95% CI: 0.86–1), specificity 100% (65% CI: 0.93–1), positive predictive value (PPV) 100% (95% CI: 0.83–1), and negative predictive value (NPV) 100% (95% CI: 0.93–1). Blood culture was positive in 12 patients only, with a sensitivity of 38% (95% CI: 0.22–0.57), a specificity of 100% (65% CI: 0.93–1), PPV 100% (95% CI: 0.69–1), and NPV 77% (95% CI: 0.68–0.86). Isolated Hib strains were sensitive to ceftriaxon in 91% of cases, followed by ampicillins in 31% and cotrimoxazole in 17%. Three patients had multidrug resistant strains of Hib.
Conclusion: Haemophilus influenzae type b infection is still an important and frequent pathogen causing community-acquired pneumonia in Egypt with changeable antibiotic sensitivity pattern. PCR represented a sensitive and rapid tool for the diagnosis of Hib pneumonia. Governmental plans to eradicate Hib in our community with the introduction of Hib conjugate vaccine in the national immunization program became indispensable.

Keywords: Haemophilus influenzae type b; Egyptian children; PCR; Culture; Antibiotic sensitivity