A Comparative Study of Bacterial Isolates Cultured From the Nasopharynx of Children With and Without Sickle Cell Disease at a Tertiary Healthcare Institution in Nigeria - Abstract
Background: Children with sickle cell disease have been shown to be at greater risk of bacterial infections from Streptococcus pneumoniae, Hemophilus influenzae and Salmonella enteritidis and from complications of septicaemia, pneumonia, respiratory difficulty and bone pain. The study compared the nasopharyngeal bacterial carriage of 87 children with sickle cell disease (SCD) and 160 children without SCD, ranging in age from four months to fifteen years. The study, conducted at the Wesley Guild Hospital, Ilesa in south- western Nigeria between January and November 2014, also looked at the antibiotic resistance profiles of the bacterial isolates and the presence of specific resistance and virulence genes.
Methods: Samples were collected from each study participant with the aid of a cotton-tipped applicator initially dipped into sterile saline and introduced into nasopharynx of subject, applied onto sterile thioglycolate fluid medium and incubated at 37oC for 24 hr. When growth was noticed, a loopful was retrieved and applied onto blood and chocolate agar as well as other selective and differential media. Bacterial colonies that grew on such media were picked and studied initially by Gram reaction, cultural and biochemical methods. Antibiotic susceptibility testing was done for selected bacterial isolatesalong with PCR demonstration of resistance and virulence genes.
Results: The results showed that the 1-5 and the 5-10 year SCD childrenhad the highest frequency of bone pain episode, hospitalization for malaria, bacterial infections and sepsis and blood transfusions for chronic anemia. Corynebacterium spp predominated among the nasopharyngeal isolates from both SCD and non-SCD children. C. Xerosis accounted for 55.38% among the non- SCD isolates and C. Ulcerans represented 35.84%of the SCD isolates.We recorded low carriage rates for H. influenzae, S. Pneumonia and S.aureus in the nasopharynx of the study participants. Widespread antibiotic resistance was observed among SCD and non-SCD isolates, with demonstration of resistance blaZ and tetK resistance genes and sea, and eta virulence genes by PCR.
Conclusion: The predominance in this study of Corynebacterium spp over organisms such as H. influenzae,S. Pneumonia and S. aureus that are common invasive pathogens of the nasopharynxwas both interesting and unexpected. The predominance suggested a shift in the community nasopharyngeal flora that may have resulted from long-term prophylactic use of antibiotics and successful administration of bacterial vaccines in the study population.