Amidst the ongoing injection drug use (IDU) public health crisis in the US, the rise of Staphylococcus aureus (S. aureus) IDU-associated bloodstream infection (IDU-BSI) presents another potential epidemic that could affect thousands of lives. The community-level spread of this phylogenetically distinct set of subtypes of the bacterium among the IDU community is primarily propagated by the high-risk practice of needle sharing. A recent study found that S. aureus infections among IDU users can spread like communicable diseases and increased from 9.1% of BSI cases in 2016 to 13.4% in 2019. GlobalData epidemiologists expect that if the issue remains unaddressed, an increase in S. aureus-related bacteremia will likely be observed, a major risk factor for developing the life-threatening condition of severe sepsis.
Bacteremia is the condition where bacteria, such as S. aureus, enter a person’s bloodstream where it should not be. It can affect anyone, although healthy individuals with bacteremia can recover without medication and without experiencing symptoms of fever and chills. However, if an infection is established in the bloodstream and is left untreated, it could lead to severe sepsis. This is a serious condition in which the body’s extreme inflammatory response damages organs, leading to symptoms such as no urine output, difficulty breathing, and extreme weakness. Bacteremia prevention is vital in minimising the risk of a serious condition like severe sepsis; GlobalData epidemiologists predict 1.5 million Americans will be affected by the end of 2021, and it is projected to affect nearly 2 million by 2030 (as shown in Figure 1). However, if the rise of S. aureus remains unchecked, diagnosed incident cases of severe sepsis will likely surpass the current forecast estimates.
Figure 1: Diagnosed Incident Cases (N) of Severe Sepsis in the US, 2021-2030, (Men and Women) (All Ages). Source: GlobalData
A 2021 US Midwestern case-control study by Marks and colleagues, published in Communications Medicine, investigated whether injection drug users were at higher risk of bloodstream infection by S. aureus compared to non-users. The complete genome sequence of participants with bloodstream infection by S. aureus who inject drugs (n=154) and those who did not (n=91) was obtained and compared after phylogenetic and clonal analysis. The findings revealed S. aureus isolates from IDU-BSI patients fell into several distinctive clonal clusters; this clonal expansion of several lineages witnessed in IDU-BSI isolates was not seen in non-IDU-BSI isolates. All this suggests that, not only was person-to-person community-level transmission of S. aureus propagated through communities that practice high-risk activities like needle sharing, but also the spread of this unique set of S. aureus strains was seemingly confined to the same community too.
Research has a crucial role to play in helping public health officials develop a multifaceted approach for effectively reducing risk factors of S. aureus IDU-BSI and tackling the larger IDU crisis in the US.