Temkin E, et al. - For the first time, researchers estimated the number of infections worldwide that are caused by the WHO priority pathogens third-generation cephalosporin-resistant and carbapenem-resistant Escherichia coli and Klebsiella pneumoniae using data from 17 countries. The estimates in this study were higher in comparison to the US Centers for Disease Control and Prevention (CDC)'s estimates—for example, the US CDC estimated that 9300 hospital-acquired infections were caused by carbapenem-resistant E coli and K pneumoniae, whereas this study estimated that 33,994 (interval estimate 19,163–48,824) inpatient infections were caused by these microorganisms. As data on resistance levels from low-income and middle-income countries was scanty and knowledge regarding resistance dynamics when resistance is high appeared insufficient, uncertainty regarding conclusion remained.

Methods

• A uniform weighted mean incidence of serious infections caused by antibiotic-susceptible E coli and K pneumoniae was calculated using data from 17 countries.
• The number of infections caused by third-generation cephalosporin-resistant and carbapenem-resistant E coli and K pneumoniae in 193 countries in 2014 were determined using the uniform incidence, as well as population sizes and country-specific resistance levels.
• Interval estimates derived from changing the fixed incidence of susceptible infections to 1 SD below and above the weighted mean were also calculated.
• An additive model was compared with combination models in which susceptible infections replaced resistant infections.
• Higher-certainty regions (those with good-quality data sources for resistance levels and resistance ≤30%), moderate-certainty regions (those with good-quality data sources for resistance levels and including some countries with resistance >30%), and low-certainty regions (those in which good-quality data sources for resistance levels were unavailable for countries comprising at least 20% of the region's population, regardless of resistance level) were differentiated.

Results

• In 2014, third-generation cephalosporin-resistant E coli and K pneumoniae caused 6·4 million (interval estimate 3·5–9·2) bloodstream infections and 50·1 million (27·5–72·8) serious infections, as per estimates generated via the additive model; estimates were 5·5 million (3·0–7·9) bloodstream infections and 43·1 million (23·6–62·2) serious infections in the 25% replacement model, 4·6 million (2·5–6·6) bloodstream infections and 36·0 million (19·7–52·2) serious infections in the 50% replacement model, and 3·7 million (2·0–5·3) bloodstream infections and 28·9 million (15·8–41·9) serious infections in the 75% replacement model.
• Based on the additive model, carbapenem-resistant strains were noted causing 0·5 million (0·3–0·7) bloodstream infections and 3·1 million (1·8–4·5) serious infections; based on the 25% replacement model, 0·5 million (0·3–0·7) bloodstream infections and 3·0 million (1·7–4·3) serious infections;based on the 50% replacement model, 0·4 million (0·2–0·6) bloodstream infections and 2·8 million (1·6–4·1) serious infections and; based on the 75% replacement model, 0·4 million (0·2–0·6) bloodstream infections and 2·7 million (1·5–3·8) serious infections.