A new perspective to invasive bacterial infections in The Gambia: Surveillance of etiological agents responsible for admission of patients in the clinic

Abstract

Background: Between November 2003 and February 2005, Medical Research Council Laboratories conducted a study to access the causative organisms of bacteraemia among admitted patients. The study confirmed Streptococcus pneumoniae as the leading cause of bacteraemia and it led to the introduction of pneumococcal conjugate vaccines into the EPI. It is important to continuously monitor the introduction of vaccine with a surveillance system in order to identify changes in the incidence of invasive bacterial infections. So, we monitored patients admitted for febrile illness. Methods & Materials: Between January 2010 and June 2013, a total of 2,938 blood culture vials were received for the purpose of identification of invasive bacterial infections in Clinical Research Laboratories of MRC. 95.1% (2,793) of these blood cultures represents patients that were admitted. These patients were categorized into three age groups: ≤ 5, 6-14 and ≥ 15 years old. Bacterial isolates were isolated using an automated blood culture system BACTEC 9050 (Becton Dickinson, Temse, Belgium) along with commercially produced BD BACTECTM PEDS PLUSTM /F culture, BD BACTECTM Plus Aerobic/F and Plus Anaerobic/F vials. Standard microbiological procedures and further identification by biochemical and serological methods. All procedures were performed in a laboratory that is in compliance with GCLP standards. Results: Out of the admitted patients studied,1,557 (53.7%) were males. The age range was 24 hours to 107 years old. A total of 732 (24.7%) isolates were isolated but 230 (31.3%) represents pathogenic agents. The three common pathogens were Staphylococcus aureus (60 representing 26.1%), Streptococcus pneumoniae (41 representing 17.8%) and Escherichia coli (25 representing 10.9%). S. aureus was identified as the leading cause of admission among the age groups of ≤ 5 and 6-14 years old, followed by S. pneumoniae. E.coli was largely responsible for the admission of ≥ 15 years old patients. Conclusion: These findings are in contrast with previous data in which S. pneumoniae was identified as the leading cause of invasive disease. This report is suggestive of a change in the pattern of etiology of bacteraemia and a new approach may be required in the prevention of staphylococcal infection.