Fréquence de détection des bactéries et typage moléculaire des Haemophilus chez les patients souffrant d’infection des voies respiratoires à Yaoundé

Abstract

Respiratory diseases are the major cause of morbidity and mortality worldwide, with Africa being one of the most affected continents. Bacteria among which Haemophilus is one of the main causes and little information is available with regard to Cameroon. The objective of this study was to detect bacteria in patients suffering from respiratory tract infections in Yaoundé, and to characterize the Haemophilus isolates. This was a prospective descriptive study in the city of Yaoundé which took place from 2017 to 2018. The clinical samples collected from patients with respiratory tract infections were subjected to culture and an RT-PCR for the search for respiratory bacteria. Haemophilus isolates were identified using a phenotypic, proteomic and genotypic approach followed by determination of capsular type, antibiotic resistance profile and genetic diversity. The data were analyzed using SPSS software with a significance level set at <5%. A total of 440 participants were enrolled in this study. Bacteria were detected in 68% (299/440) of patients and could be grouped as Gram negative with 47% (207/440), Gram positive with 35.7% (157/440), atypical with 4.3% (19/440) and mycobacteria with 8.6% (38/440). Haemophilus sp. were the most detected bacteria regardless of the methods used, followed by pneumococci : 21.6% and 10.9% respectively per culture. The frequency of bacterial detection by culture was 32% (141/440) versus 58.6% (258/440) by RT-PCR (p<0.001). Factors associated with bacterial detection were socio-demographic and clinical. Identification of the 95 Haemophilus isolates revealed 76.8% Haemophilus influenzae, 14.7% Haemophilus haemolitycus and 6.3% Haemophilus parainfluenzae. These isolates were very genetically diverse. Of the 73 isolates of Haemophilus influenzae, 3 encapsulated isolates (4.1%) were identified (types b, e and f). The antibiotic resistance profile of Haemophilus sp. was dominated by that to sulfonamides (99%) followed by that to β-lactams (55.3%). Molecular changes associated with antibiotic resistance include target modification (mutation) and production of enzymes. Haemophilus sp. and pneumococci were the bacteria most detected in this study. The molecular tool used during the investigation increased the yield of bacterial detection. The Haemophilus species circulating in Yaoundé are variable and present a high genetic diversity. The circulation of Haemophilus influenzae type b today remains a threat to public health, as does resistance to antibiotics.