Trends and pattern of antimicrobial resistance among blood culture isolates of selected bacterial pathogens in South Africa, 2005-2009

Document Type



Population Health (East Africa)


Background: To investigate prevalence, patterns and time trends of resistance to commonly used antibiotics and factors associated with antimicrobial resistance of selected isolates from blood-specimens collected from patients with bacteraemia and submitted to diagnostic microbiology laboratories at 7 tertiary public hospitals in South Africa.
Methods: We conducted a retrospective cohort analysis of routine data of blood culture-positive Staphylococcus aureus (SA), Klebsiella pneuomoniae (KP), and Psuedomonas aeruginosa (PA) submitted to the National Health Laboratory Services (NHLS) between January 1, 2005 and December 31, 2009. Antimicrobial resistance to commonly used antimicrobials was systematically investigated. Multivariable logistic regressions models were used to assess factors associated with antimicrobial resistance.
Results: A total of 9,969 isolates were reported 3942 (39.5%) SA, 4466 (44.8%) KP and 1561 (15.7%) PA. There were more resistant isolates in 30-39 years age-group for SA 28.4% and PA 51.5%. For KP, 73.3% were in the 5-9 years age-group. SA and PA resistance was similar between males and females, for KP 66.8% were among females; 47.9% SA, 72% KP and 67.1% PA respectively were found to be resistant in three different hospitals from three provinces. SA resistance to ampicillin was >98% and to vancomycin <0.1%. KP resistance to carbapenems was very low: ertapenem 2% (range 0.5%-4.6%), imipenem 0.1% (range 0%-0.5%) and meropnem 0.1% (range 0%-0.3%); and to colistin 1.7% (range 0-2.6%). PA resistance to colistin was 1.9% (range 0 - 13.3%). There was a significant increase in trend of KP resistance to ciprofloxacin (32.6% to 64.9%, p<0.001), cotrimoxazole (67.5% to 81.6%, p<0.001) and cefazolin (80.9% to 95.7%, p<0.00)1. PA resistance to meropenem showed a significant increasing trend from 2006 (27.5%) to 2009 (53.9%) p<0.001. Age group <5 years; female sex; hospital location and year of infection were significantly associated with antimicrobial resistance.
Conclusion: The prevalence of antimicrobial resistance was high among children <5 years old and females with bacteraemia. Enhancement of continued surveillance of hospital acquired infections is therefore recommended as trend of antimicrobial resistance is increasing. Such data would provide understanding of the extent of the problem and present evidence for future policies and practices aimed at containing antimicrobial resistance.


This work was published before the author joined Aga Khan University.

Publication (Name of Journal)

International Journal of Infectious Diseases