Risk of non-typhoidal salmonella vascular infection increases with atherosclerosis, find NCKU researchers

Although foodborne bacteria are a common occurrence, some of them can cause serious and life-threatening infections. Non-typhoidal Salmonella (NTS) is one such bacterium, known to cause vascular infections (NTS vascular infections) with serious consequences. According to studies, such vascular infections develop in approximately 9%–40% of patients aged ≥50 years with NTS bacteremia. Clinical evidence points to the occurrence of vascular infection due to bacterial seeding in the damaged atherosclerotic aorta (fat and calcium plaque built-up in large blood vessel) of patients with NTS bacteremia, suggesting atherosclerosis to be a risk factor for developing infection. However, this association of NTS vascular infection and atherosclerosis lacks evidential support from rigorous clinical studies.

To address this gap, a group of researchers from Taiwan led by Dr. Po-Lin Chen and Dr. Wen-Chien Ko, Professors in the Department of Internal Medicine, National Cheng Kung University (NCKU) Hospital, conducted a prospective study to examine this association further. Talking about the study, Prof. Chen says, “We attempted to evaluate the risk of NTS vascular infection with atherosclerosis by examining aortic calcification and serum levels of inflammatory biomarkers in patients with NTS bacteremia. We also tested the validity of the NTS vascular infection score proposed in our previous research for determining infection risk.”  This study was made available online on 21 June 2022, and subsequently published in Volume 55, Issue 3 of the Journal of Microbiology, Immunology and Infection.

In this study, 69 patients with NTS bacteremia (mostly comprising males aged ≥50 years) underwent abdominal and/or thoracic CT scan to detect vascular infection. Atherosclerosis severity was measured by obtaining the aortic calcium scores from unenhanced CT calcium scanning.

The NTS vascular infection score (NTSVI) proposed by Prof. Chen and his colleagues in a previous study was calculated based on four risk factors, of which hypertension and coronary artery disease are directly linked to atherosclerosis. Blood plasma levels of important inflammatory markers were also analyzed for this investigation.

The researchers found that calcium scores were higher in patients with NTS vascular infection when compared with those without the infection. As for the NTSVI score, none of the patients with a score less than 1 reported vascular infection. Rather, the prevalence of infection was found to increase with increasing score, validating the score’s predictive ability.

Of the five biomarkers assayed using blood plasma samples, higher concentrations were detected only for interleukin 1 beta (IL-1β)¬–an inflammatory cytokine protein, in patients with vascular infection when compared with those without infection.

Discussing the results, Prof. Chen says, “Higher calcium scores in patients with NTS vascular infection indicates that the risk of developing vascular infections is high with atherosclerotic severity. The NTSVI score, which also determines atherosclerotic severity, can be used with ease in clinical settings to categorize patients based on the risk of vascular infection.”  

Moreover, this research also supports the hypothesis about the pivotal role IL-1β plays in Salmonella infections, as suggested by previous studies. Plasma levels of IL-1β among patients with NTS bacteremia have significant clinical relevance as a potential biomarker as well as a therapeutic target among high-risk patients.

Explaining the real-life applications of these results, Prof. Ko says, “With an overall increase in aging and atherosclerosis, susceptibility to NTS vascular infections also increases. Moreover, the mortality rate associated with delayed diagnosis is high. In such a situation, if a patient with NTS bacteremia is found to have risk factors of atherosclerosis, aggressive examination using a comprehensive CT scan for diagnosing coexisting NTS vascular infection is recommended.”

Though further rigorous and exhaustive studies are required to validate the use of NTSVI score and IL-1β as an inflammatory biomarker, this study has set the ball rolling for early detection and appropriate remediation of this life-threatening infection. 

***

Reference

DOI: https://doi.org/10.1016/j.jmii.2021.04.007

Authors: Ying-Wen Chen^a, Hung-Jen Tang^b,c, Yi-Shan Tsai^d,e, Nan-Yao Lee^a,e,f, Yuan-Pin Hung^e,g,h, Chien-Fang Huangⁱ, Ching-Chi Lee^a,j, Chia-Wen Li^a,e,f, Ming-Chi Li^a,e,f, Ling-Shan Syue^a,f, Shu-Li Su^k, Shu-Hao Hsu^e, Wen-Chien Ko^a,e,f,k, Po-Lin Chen^a,f,k,l

Affiliations:

^a Department of Internal Medicine, National Cheng Kung University Hospital, College of Medicine, NCKU

^b Department of Medicine, Chi Mei Medical Center, Tainan, Taiwan

^c Department of Health and Nutrition, Chia Nan University of Pharmacy and Science

^d Department of Diagnostic Radiology, National Cheng Kung University Hospital, College of Medicine, NCKU

^e Department of Medicine, College of Medicine, NCKU

^f Infection Control Center, National Cheng Kung University Hospital, College of Medicine, NCKU

^g Department of Internal Medicine, Tainan Hospital, Ministry of Health and Welfare

^h Graduate Institute of Clinical Medicine, National Health Research Institutes

^I Department of Internal Medicine, Kuo General Hospital

^j Clinical Medicine Research Center, NCKU Hospital, College of Medicine, NCKU

^k Diagnostic Microbiology and Antimicrobial Resistance Laboratory, NCKU

^l Department of Microbiology and Immunology, College of Medicine, NCKU

About NCKU, Taiwan
Established first in 1931 under the name of Tainan Technical College, National Cheng Kung University (NCKU) is a public university in Tainan, Taiwan. Currently spread over a total area of approximately 186 hectares, including 8 main campuses and 3 satellite campuses, NCKU has come a long way since its inception 90 years ago. With 9 colleges, 44 departments, and 15 university-level research centers, NCKU aims to cultivate critical thinking, empathy, and imagination, and strives to improve the wellbeing of humankind and become a university of excellence in education, research, and social responsibility. “Seek for Truth; Toil for Good” is the university’s motto.

Website: https://www.ncku.edu.tw/ 

About Dr. Po-Lin Chen
Dr. Po Lin Chen is a Professor affiliated with NCKU. His areas of expertise include clinical medicine, infectious disease epidemiology, infectious disease medicine, and internal medicine. Prof. Chen has contributed his expertise to more than 130 research publications throughout his career. He believes in undertaking impactful research that can translate into maximum benefit for the society.

About Dr. Wen-Chien Ko
Dr. Wen-Chien Ko graduated from the medical school of Kaohsiung Medical University, Kaohsiung, Taiwan, and is currently a Professor affiliated with NCKU Hospital. His research interests include the pathology and immunology associated with infectious diseases including Aeromonas infection, Clostridium difficile infection, and related antimicrobial resistance, and antimicrobial therapy. He has published over 450 articles in reputed medical and life sciences journals.