Trend analysis of antibiotic resistance in KwaZulu-Natal : a retrospective study 2011- 2015.
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Objective: Antimicrobial resistance is a global phenomenon which is limiting treatment options for common infections resulting in poor clinical outcomes, increased mortality and increased cost of healthcare. Antibiotic resistance trends in pathogen-drug combinations stipulated in the Global Antimicrobial Surveillance System (GLASS) of the World Health Organization were investigated for the period 2011-2015 in the province of KwaZulu Natal, South Africa. Methods: Antibiotic susceptibility data from blood, urine, faecal and urethral/cervical samples was retrospectively analyzed from six public hospitals. Pathogens included Escherichia coli, Streptococcus pneumoniae, Klebsiella pneumoniae, Salmonella spp., Acinetobacter baumannii, Staphylococcus aureus, Shigella spp. and N. gonorrhoea. Results were analyzed as MIC50, MIC90, percentage resistance, incidence of monitored infections in the population and proportion of nonsusceptible infections per pathogen. Results were also evaluated against South African treatment guidelines. Significant differences in resistance proportions by year were identified using the Pearson χ2 test. Comparison of MIC50 were analysed using the equality-of-medians test. Findings: Urine samples were most abundant (61.22%, n= 33 018) and E. coli (52%) was the most common pathogen. Most isolates were multi-drug resistant. Resistance to third and fourth generation cephalosporins and fluoroquinolones increased in K. pneumoniae, E. coli and Shigella spp. over the 5- year period. Notable changes in resistance were: K. pneumoniae from blood samples to carbapenems (1 – 26%, p< 0.001) and A. baumannii to carbapenems (69% - 50%, p-value not available). Susceptibility to antibiotics recommended in treatment guidelines was >50% for most pathogen-drug combinations. Conclusion: The results of this study show that antibiotic resistance in hospitals in KwaZulu-Natal generally increased from 2011 to 2015, although some pathogen-drug combinations showed a plateau or decline in resistance necessitating a review of the existing treatment guidelines. To our knowledge, this is the first South African report on ABR using GLASS metrics. There is a need for more extensive research in order to build an accurate, comparable picture of ABR in South Africa.