In a recent study published in The Lancet, researchers presented comprehensive global estimates of the mortality burden related to 33 species or genera of bacterial pathogenic organisms causing 11 main infectious syndromes in 2019 using data and methods of the GBD (global burden of diseases, injuries, and risk factors study) 2019 and the global burden of antimicrobial resistance study conducted in the same year.
Studies predicting mortality due to drug-resistant organism infections and associated sepsis reported that infections continue to be a major death cause across the globe. Therefore, deaths due to infections should be considered an urgent priority for intervention within the global health community. Identifying the pathogens associated with leading infections, infectious syndromes, and associated deaths for every region is critical for implementing targeted prevention efforts.
About the study
In the present study, researchers predicted fatalities that occurred in 2019 due to infections caused by 33 bacterial species or genera responsible for 11 main infectious syndromes based on data and methodology of the GBD study and the global burden of antimicrobial resistance study conducted in 2019.
The study comprised records of 343 million individuals spanning over 11,361 study-geographic location years. Three modeling steps were used for fatal burden estimation associated with the bacterial pathogens, which were: (i) deaths attributed to infections, (ii) the proportion of fatalities due to infections attributable to particular infectious syndromes, and (iii) the proportion of fatalities due to infectious syndromes attributable to particular pathogenic organisms.
The team predicted mortality attributed to infections based on death counts for which the death cause was infectious, or the death occurred due to sepsis. The proportion of fatalities due to bacterial infections attributable to particular infectious syndromes was estimated based on data analyzed for determining the infectious syndromes that led to sepsis by the causative organism, sex, geographic location, and age.
The proportion of fatalities due to particular infectious syndromes attributable to specific pathogens was predicted by the integration of estimates of pathogenic organism-specific and infectious syndrome-specific case-fatality ratios (CFRs) with modeled pathogenic organism distributions for every infectious syndrome varying by geographic location and age. Predictions were generated for all females and males of all ages residing in 204 territories and nations in the year 2019.
Random-effects logistic regression modeling and MEPCO (multinomial estimation with partial and composite observations) modeling were used for the analysis. The team predicted YLLs (years of life lost) associated with every pathogenic organism by conversion of age-stratified deaths into YLL estimates based on the standardized counterfactual life expectancy at a particular age.
Data source types eligible to be included in the study comprised data as follows: vital registration data of deaths due to multiple causes; discharge data from hospitals; linkage information sources; death surveillance data of the CHAMPS (child health and mortality prevention surveillance ) study; laboratory-based data of passive surveillance; and literature reviews on microbial organisms responsible for meningitis, lower respiratory tract infections, neonatal sepsis, dermatological infections, urinary tract infections, bone and joint-related infections, and peritonitis.
In total, 14 million infection-associated deaths were estimated in 2019, of which eight million fatalities were related to bacteria (susceptible and resistant to antimicrobial agents) responsible for the infectious syndromes analyzed in the study. Mortality due to the bacterial pathogenic organisms investigated was estimated to comprise 14% of all worldwide fatalities and 56% of sepsis-related fatalities in 2019.
The top five bacterial pathogenic organisms responsible for 55% of fatalities due to bacterial organisms investigated were Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Pseudomonas aeruginosa, and Streptococcus pneumoniae. The most lethal pathogenic organisms resulting in the most fatal infectious syndromes varied by age and location. The age-stratified mortality estimates associated with the bacterial pathogenic organisms investigated were the greatest in the African sub-Saharan super-area, with predicted 230.0 fatalities among every 100,000 individuals, and least among high-income individuals, with 52.0 fatalities in every 100,000 individuals.
Staphylococcus aureus was associated with the highest number of fatalities in 135 nations and with the highest number of global fatalities among individuals aged >15 years, whereas Streptococcus pneumoniae was responsible for most of the fatalities among those aged <5.0 years. In 2019, >6.0 million deaths resulted from three infectious syndromes of bacterial origin, with bloodstream and lower respiratory tract infections each resulting in >2.0 million fatalities and>1.0 million fatalities occurring due to intra-abdominal and peritoneal infections each.
There were 304 million YLLs associated with the bacterial pathogenic organisms investigated worldwide in 2019, representative of 18% of global YLL estimated for 2019. The bacterial pathogens associated with the YLL burden were identical to fatality estimates with S. pneumoniae, S. aureus, K. pneumoniae, E. coli, and P. aeruginosa associated with 40 million YLLs, 34 million YLLs, 31 million YLLs, 30 million YLLs, and 19 million YLLs, respectively.
Overall, the study findings provided an audit of the mortality associated with commonly identified bacterial pathogenic organisms and showed that >50%of all bacterial deaths worldwide in 2019 were caused by E. coli, S. aureus, K. pneumoniae, P. aeruginosa and S. pneumoniae.
The findings can guide health strategies for decreasing the global bacteria-origin infection burden, including measures for infection control and prevention, optimization of antibiotic use, improved microbial analysis capacity, development and implementation of vaccines, increased pervasiveness of available vaccine use, and basic care service availability.