Older Age Linked to Higher Incidence of Complicated Pneumococcal Bacteremia

Older age, along with conditions such as septic arthritis, endocarditis, and pneumonia, are factors significantly associated with complicated pneumococcal bacteremia, according to data presented at IDWeek, which took place from October 19 to October 22, 2025, in Atlanta, Georgia.¹

What is Pneumococcal Bacteremia?

Pneumococcal bacteremia occurs when the bacteria causing pneumococcal disease, Streptococcus pneumoniae, enters the bloodstream. It most often occurs in immunocompetent and immunosuppressed patients, and although it can begin as a primary infection, it is one of the most common manifestations of invasive pneumococcal disease (IPD).^2,3

Treatment for pneumococcal bacteremia can be difficult because of a lack of localized symptoms and indications of infection; however, concern lies with where the infection has spread. This distinction separates uncomplicated from complicated pneumococcal bacteremia, with the former encompassing patients without an uncontrolled infection source requiring treatment longer than 2 weeks. Contrastingly, patients with complicated pneumococcal bacteremia may face deep-seated infections spreading to the bones, lungs, or joints.^2-4

Particularly severe complicated bacteremia can induce sepsis and septic shock or cause infections in distant sites, such as meningitis, endocarditis, and septic arthritis. The case-fatality rate for pneumococcal bacteremia hovers around 20%, but depending on age and comorbidities, it could be as high as 60%. Prompt treatment is essential because the risk of death is highest within the first 3 days of bacteremia.^2,3

Invasive pneumococcal bacteremia can manifest in approximately 20% to 25% of patients with pneumococcal disease. Due to the complexity, duration, and burden of this illness, determining solidified risk factors for bacteremia—and the role of preventive measures within communities—is of paramount importance. Pneumococcal vaccines can protect against the development of IPD, in turn preventing the possibility of bacteremia and other severe outcomes. Ensuring proper uptake of these vaccines is critical for the health of at-risk patients.¹

What Factors Lead to Complicated Versus Uncomplicated Pneumococcal Bacteremia?

The current retrospective analysis led by investigators at Saint Louis University School of Medicine sought to examine factors contributing to uncomplicated versus complicated pneumococcal bacteremia. In their research, they focused on cardiac involvement and the role of vaccines in prevention within communities. They initiated a 6-year retrospective review of data collected from the medical records of patients admitted to SSM Health Saint Louis University Hospital and Saint Louis University between 2018 and 2024.¹

Investigators defined complicated bacteremia as any occurrence where bacteremia led to secondary complications or involved other parts of the body, including the bones, brain, heart, or other organs.¹

Following their analysis, the authors found that patients with a median age of 64 years (IQR = 19) were found to have a higher incidence of complicated bacteremia (P = .002). Furthermore, patients with a median height of 167.6 cm (IQR = 16.6; P = .005) and a median weight of 72.6 kg (IQR = 28.4; P = .009) demonstrated a significant relationship with complicated bacteremia.¹

A series of conditions were found to have statistically significant relationships with complicated bacteremia. Septic arthritis (6/153, 3.9%; P = .017), septic emboli (6/153, 3.9%; P = .017), endocarditis (15/153, 9.8%; P < .001), empyema (144/153, 94.1%; P < .001), and pneumonia (139/153, 90.8%; P < .001) were all significantly associated with complicated pneumococcal bacteremia.¹

Other factors were associated with complicated bacteremia. These included having a median albumin level of 3 (IQR = 0.9; P < .005), a median white blood cell count of 15.1 (IQR = 13.8; P = .005), and intensive care unit admission (54.9%, 84/153; P = .002).¹

Interestingly, vaccination was not associated with less complicated bacteremia. The investigators noted that several factors could account for this observation, including patient-specific aspects that necessitate further research. Still, just 12% and 13% of patients in each respective group received a full pneumococcal vaccine course, and about half of each group received at least 1 pneumococcal vaccine, according to the investigators.¹

The research highlights key risk factors for complicated pneumococcal bacteremia, with older age being a prominent factor that leads to severe outcomes. Pharmacists should ensure that patients in this age group are counseled on the benefits of pneumococcal vaccination to prevent both IPD and bacteremia.¹

REFERENCES

1. Jayawardena R, Gill CM, Chamberland RR, Poowanawittayakom N. (P-53) Analyzing the risks of complicated S. pneumoniae bacteremia: Community vaccine uptake and preventive measures in real-world scenarios. Presented: IDWeek; October 20, 2025; Atlanta, GA. Accessed via IDWeek Virtual Platform on November 20, 2025.

2. Disease information about pneumococcal disease. European Centre for Disease Prevention and Control. Last Updated November 28, 2023. Accessed November 20, 2025. https://www.ecdc.europa.eu/en/pneumococcal-disease/facts#:~:text=Bacteraemia%20is%20the%20most%20common,and%20distribution%20of%20invasive%20S.

3. Bush LM, Vazquez-Pertejo MT. Pneumococcal infections. Merck Manual Professional Version. Last Updated October 2025. Accessed November 20, 2025. https://www.merckmanuals.com/professional/infectious-diseases/gram-positive-cocci/pneumococcal-infections

4. Sutton JD, Sayood S, Spivak ES. Top questions in uncomplicated, non-Staphylococcus aureus bacteremia. Open Forum Infect Dis. 2018;5(5):ofy087. doi:10.1093/ofid/ofy087