Thrombus Aspirates From Patients With Acute Ischemic Stroke Are Infiltrated by Viridans Streptococci

Area of Science:

• Microbiology
• Neurology
• Cardiovascular Science

Background:

• Acute ischemic stroke can result from emboli originating from ruptured atherosclerotic carotid arteries.
• Oral bacteria, particularly viridans streptococci, have been detected in thrombi and carotid samples from stroke patients.
• Viridans streptococci are known for their thrombogenic properties, prompting investigation into their presence in stroke-related tissues.

Purpose of the Study:

• To confirm the presence of viridans streptococci group bacteria in thrombus aspirates from ischemic stroke patients.
• To investigate the presence of these bacteria in carotid artery specimens from both symptomatic patients and nonstroke controls.
• To utilize bacterial immunohistochemistry for accurate detection and confirmation.

Main Methods:

• Immunohistochemistry was employed to detect viridans streptococci (Streptococcus sanguinis, Streptococcus mitis, Streptococcus gordonii).
• Samples analyzed included thrombus aspirates from 61 ischemic stroke patients and carotid endarterectomy samples from 20 symptomatic patients.
• Control samples comprised carotid artery specimens from 48 nonstroke autopsy cases.

Main Results:

• A high percentage of thrombus aspirates (84.8%) and carotid endarterectomy samples (80.0%) tested immunopositive for viridans streptococci.
• A lower prevalence (31.3%) was observed in carotid artery samples from nonstroke autopsies.
• Streptococci were primarily found within neutrophil granulocytes, with evidence of biofilm and free infiltrates in some cases.

Conclusions:

• Oral streptococci were detected in thrombi from acute ischemic stroke patients and in carotid artery specimens.
• These findings suggest a potential role for viridans streptococci group bacteria in the pathophysiology of ischemic stroke.