Common bacterial infections as the second leading cause of death globally after ischaemic heart disease.

7,7 million deaths were attributed to 33 common bacterial infections in 2019, with five bacteria alone accounting for more than half of all deaths. The most lethal bacterial infections and infection types vary by age and place.

The analysis shows that reducing bacterial infections is a top priority for global public health. Bacterial infections are only second to ischaemic heart disease as the leading cause of death in 2019. Building better health systems with increased diagnostic laboratory capacity, implementing control measures, and optimizing antibiotic use are essential for reducing the illness burden resulting from common bacterial infections.

“These new data for the first time reveal the full extent of the global public health challenge posed by bacterial infections,” says co-author Dr. Christopher Murray. “It is of utmost importance to put these results on the radar of global health initiatives so that a deeper dive into these deadly pathogens can be conducted and proper investments are made to slash the number of deaths and infections.”

There are many estimates for pathogens like tuberculosis, malaria, and HIV, but until now, estimates of the disease burden of bacterial pathogens were limited to a small number of specific pathogens and types of infection, or they only looked at certain populations. In 2019, 864,000 deaths were attributed to two of the deadliest infections, S. aureus and E. coli, however an investigation showed that HIV research received $42 billion while E. coli research only received $800 million. According to the authors of the study, the absence of data on the worldwide burden of these infections may have been a contributing factor in the existence of such financing disparities.

The current study offers the first global estimates of mortality linked to 11 major infectious syndromes and 33 prevalent bacterial infections, which are known collectively as infectious syndromes and can result in sepsis-related death. Estimates were generated for every age group, as well as both genders and for all 204 countries and territories. Using data and methods from the Global Burden of Disease 2019 and Global Research on Antimicrobial Resistance (GRAM) studies [2], the authors used 343 million individual records and pathogen isolates to estimate the number of deaths caused by each pathogen and the type of infection that caused them.

About 7.7 million of the estimated 13.7 million deaths from infections in 2019 were caused by the 33 bacterial pathogens that were studied. In 2019, these bacteria were linked to 13.6% of all deaths around the world and more than 50% of all deaths caused by sepsis. Three syndromes—lower respiratory infections (LRI), bloodstream infections (BSI), and peritoneal and intra-abdominal infections—accounted for more than 75% of the 7.7 million bacterial deaths.

Out of all the microorganisms examined, five were responsible for 54.2% of deaths: S. aureus, E. coli, S. pneumoniae, K. pneumoniae, and P. aeruginosa. With 1.1 million deaths, S. aureus was the pathogen that caused the most deaths around the world. E. coli (950 000 deaths), S. pneumoniae (829 000), K. pneumonia (790 000), and Pseudomonas aeruginosa (559,000 deaths) were the other four infections each responsible for more than 500,000 deaths. The major bacterial infections were linked to fatalities in about equal numbers of men and women.

The deadliest infections and age-standardised mortality rates varied by location. The highest mortality rate was found in Sub-Saharan Africa, where there were 230 deaths per 100,000 people. With 52 deaths per 100,000 people, the high-income super-region, which is made up of countries in Western Europe, North America, and Australasia, had the lowest death rate. In 135 nations, S. aureus was the most common bacterial cause of mortality, followed by E. coli (37), S. pneumoniae (24), K. pneumoniae, and Acinetobacter baumannii (4 countries each). 

“Until now, country-level estimates for parts of the world where people are worst affected by bacterial infections have been noticeably absent,” adds co-author Authia Gray. “These new data could act as a guide to help address the disproportionately high burden of bacterial infections in low- and middle-income countries and may ultimately help save lives and prevent people losing years of their lives to illness.”

There was a significant age difference between the infections that were connected with the greatest mortality. S. aureus was responsible for the majority of mortality in adults over the age of 15 with its 940,000 deaths. With 49,000 deaths, Salmonella enterica serovar Typhi was the cause of the greatest mortality in children between the ages of 5 and 14 years. S. pneumoniae was the most lethal pathogen in children older than newborns but younger than 5 years old, causing 225,000 deaths. K. pneumoniae was the pathogen responsible for 124,000 of the newborn fatalities.

The authors recognize that their research has some limitations, many of which stem from insufficient data. There isn’t much information about some parts of the world, especially many low- and middle-income countries (LMICs), where disease is thought to be the worst. In light of this, it is clear that LMICs must enhance their data collection capability and surveillance systems. Combining and standardizing data from many different sources can also introduce biases, such as misclassification of community- or hospital-acquired infections and data from passive surveillance systems that may overestimate the virulence or drug-resistance of pathogens.

Source: 10.1016/S0140-6736(22)02185-7

Image Credit: Getty