Susceptibility Pattern of Pathogens Causing Blood Stream Infections in a Tertiary Care Hospital: A Two-year Retrospective Study from Southern Nigeria

Abstract

Aim: Bloodstream infections are a major cause of morbidity and mortality worldwide. The prevalence of causative microorganisms varies from one geographical region to another. This study was aimed at determining the etiological agents prevalent in our environment and their susceptibility profile. Study design: This is a retrospective study carried out at the University of Calabar Teaching Hospital, Calabar, Nigeria. Methodology: Blood culture results of patients documented over a two-year period were retrieved and analyzed. Blood culture positive isolates were detected using conventional method and Oxoid signal blood culture systems. Antimicrobial sensitivity tests were carried out by Kirby-Bauer disc diffusion method. Methicillin resistance in Staphylococcus aureus and coagulase negative Staphylococcus species (CoNS) was detected by disk diffusion method using 30 µg cefoxitin disk. ESBL production was detected by phenotypic confirmatory disc diffusion test (PCDDT) and the double disc synergy test (DDST). Results: A total of 413 blood culture antimicrobial susceptibility test results were analyzed, of which 116 (28.09%) were identified as culture positive. Sixty-nine (59%) of the positive isolates were from female patients. Out of 116 positive cultures, 58.62% (68/116) were Gram positive organisms, 40.52% (47/116) were Gram negative organisms, non albicans Candida accounted for 0.86% (1/116).  Staphylococcus aureus (n=41, 35.3%) was the predominant isolate and showed high sensitivity to levofloxacin (100%), Linezolid (100%) and Amikacin (100%). Twelve isolates of S. aureus were methicillin resistant, while 1 isolate was inducible clindamycin resistant. Of the 116 isolates identified in this study, forty-three (43) were multidrug resistant with highest number of multidrug resistant isolates from Staphylococcus aureus (n=20). 21.28% (n=10) of the Gram-negative isolates were positive for extended spectrum beta lactamases. Conclusion: A high rate of antimicrobial resistance is observed among microorganisms causing blood stream infections. This emphasizes the need for antimicrobial sensitivity testing in the management of blood stream infections.