A Case of Salmonella typhi Endocarditis in Pregnancy

Salmonella typhi and endocarditis: a systematic review of case reports

Introduction

Salmonella typhi, a gram-negative bacterium responsible for typhoid fever, can infect the inner lining or valves of the heart and cause endocarditis. This systematic review aimed to report cases of S. typhi-associated endocarditis and its clinical features.

Methods

This systematic review was reported as per the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) checklist. Only case reports and case series of endocarditis caused by S. typhi, irrespective of age, gender, and demographics, were considered eligible for inclusion. To identify relevant studies, a literature search was conducted using relevant keywords on PubMed, Google Scholar, and the Cochrane Library from inception to 31 December 2023. After selecting the studies, the relevant data were extracted and pooled in terms of frequencies and percentages. A quality assessment was performed using the Joanna Briggs Institute Critical Appraisal Checklist for Case Reports.

Results

This review included seven case reports, comprising 22.2% female and 77.8% male patients. The mean age of patients was 27.9 + 12.0 years. Regarding past medical history, 33.3% (3/9) of patients had a previous cardiac pathology. Fever remained the most common complaint, occurring in 88.9% of cases. Transthoracic and transesophageal echocardiography were used to diagnose all cases, with 33.3% identifying vegetation on the mitral, aortic, and tricuspid valves. Ceftriaxone, with or without gentamycin, remained the choice of antibiotic for 88.9% of cases, and all patients responded to the offered treatment.

Conclusion

S. typhi-associated endocarditis, though rare, presents unique challenges and requires timely diagnosis. This systematic review of seven cases highlights a predominantly male population affected, with a mean age in the third decade, suggesting a higher invasiveness than other causes. The findings from this study underscore the importance of early recognition and appropriate management, primarily with antibiotic therapy. Further research with larger cohorts is crucial to refine understanding and guide policymaking for this rare but life-threatening condition.

Salmonella enterica Serovar Typhi: An Unusual Cause of Infective Endocarditis

While typhoid fever is a common infection, Salmonella enterica serovar Typhi is a rare cause of endocarditis. We describe the case of a 20-year-old male who was treated for a primary episode of microbiologically-confirmed typhoid fever. He presented six weeks post-discharge with fever and lethargy. S. Typhi was again identified in blood cultures, and echocardiography identified a mitral valve lesion. Our case suggests that a relapse of typhoid should prompt further investigation for a deep-seated infection, including consideration of echocardiographic evaluation to rule out infective endocarditis.

Salmonella infective endocarditis

OBJECTIVE

Salmonella endocarditis is so rarely reported that its clinical features, prognosis, and optimal treatment remain unclear. In this paper, we report a female with nontyphoid Salmonella endocarditis complicated with perivalvular abscess. We also review and summarize other cases reported in the English literature.

METHODS

Using the key words "Salmonella", "infective endocarditis", and "mural endocarditis" to search the PubMed database, we reviewed case reports on Salmonella endocarditis published between 1976 and 2014 and case series of infective endocarditis that included at least 500 cases.

RESULTS

Salmonella species were rare infective endocarditis pathogens. Among 16 large case series, they accounted for less than 0.01% and up to 2.9% of bacterial endocarditis cases. From 1976 to 2014, a total of 87 cases of typhoid and nontyphoid Salmonella endocarditis were reported, which included 42 cases in 1976-1984, 30 cases in 1986-2002, and 15 cases in 2003-2014. Men predominated among the cases (58.6%), and the mean age was approximately 50-60 years. The major affected valves were the mitral valves (33.3%). Mural endocarditis was common (26.4%). Perivalvular abscess was only reported in 10.5% (6 cases) of 57 cases. The overall mortality rate was 42.5% and decreased over time from 69.0% to 13.3% during the three study periods.

CONCLUSION

Salmonella endocarditis, although rare, may cause purulent infections in the perivalvular area or myocardium and lead to substantial mortality.

Pregnancy and postpartum infective endocarditis: a systematic review

The objective of this review was to describe the clinical characteristics, risk factors, and outcomes of infective endocarditis (IE) in pregnancy and the postpartum period. We conducted a systematic review of Ovid MEDLINE, Ovid Embase, Web of Science, and Scopus from January 1, 1988, through October 31, 2012. Included studies reported on women who met the modified Duke criteria for the diagnosis of IE and were pregnant or postpartum. We included 72 studies that described 90 cases of peripartum IE, mostly affecting native valves (92%). Risk factors associated with IE included intravenous drug use (14%), congenital heart disease (12%), and rheumatic heart disease (12%). The most common pathogens were streptococcal (43%) and staphylococcal (26%) species. Septic pulmonary, central, and other systemic emboli were common complications. Of the 51 pregnancies, there were 41 (80%) deliveries with survival to discharge, 7 (14%) fetal deaths, 1 (2%) medical termination of pregnancy, and 2 (4%) with unknown status. Maternal mortality was 11%. Infective endocarditis is a rare, life-threatening infection in pregnancy. Risk factors are changing with a marked decrease in rheumatic heart disease and an increase in intravenous drug use. The cases reported in the literature were commonly due to streptococcal organisms, involved the right-sided valves, and were associated with intravenous drug use.

From mice to women: the conundrum of immunity to infection during pregnancy

Resistance to infection is the ability of the host to evoke a strong immune response sufficient to eliminate the infectious agent. In contrast, maternal tolerance to the fetus necessitates careful regulation of immune responses. Successful pregnancy requires the maternal host to effectively balance the opposing processes of maternal immune reactivity and tolerance to the fetus. However, this balance can be perturbed by infections which are recognized as the major cause of adverse pregnancy outcome including pre-term labor. Select pathogens also pose a serious threat of severe maternal illness. These include intracellular and chronic pathogens that have evolved immune evasive strategies. Murine models of intracellular bacteria and parasites that mimic pathogenesis of infection in humans have been developed. While human epidemiological studies provide insight into maternal immunity to infection, experimental infection in pregnant mice is a vital tool to unravel the complex molecular mechanisms of placental infection, congenital transmission and maternal illness. We will provide a comprehensive review of the pathogenesis of several infection models in pregnant mice and their clinical relevance. These models have revealed the immunological function of the placenta in responding to, and resisting infection. Murine feto-placental infection provides an effective way to evaluate new intervention strategies for managing infections during pregnancy, adverse fetal outcome and long-term effects on the offspring and mother.

Salmonella enterica serovar Typhimurium-induced placental inflammation and not bacterial burden correlates with pathology and fatal maternal disease

Food-borne infections caused by Salmonella enterica species are increasing globally, and pregnancy poses a high risk. Pregnant mice rapidly succumb to S. enterica serovar Typhimurium infection. To determine the mechanisms involved, we addressed the role of inflammation and bacterial burden in causing placental and systemic disease. In vitro, choriocarcinoma cells were a highly conducive niche for intracellular S. Typhimurium proliferation. While infection of mice with S. Typhimurium wild-type (WT) and mutant (Delta aroA and Delta invA) strains led to profound pathogen proliferation and massive burden within placental cells, only the virulent WT S. Typhimurium infection evoked total fetal loss and adverse host outcome. This correlated with substantial placental expression of granulocyte colony-stimulating factor (G-CSF), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-alpha) and increased serum inflammatory cytokines/chemokines, such as G-CSF, IL-6, CCL1, and KC, evoked by WT S. Typhimurium infection. In contrast, infection with high doses of S. Typhimurium Delta aroA, despite causing massive placental infection, resulted in reduced inflammatory cellular and cytokine response. While S. Typhimurium WT bacteria were dispersed in large numbers across all regions of the placenta, including the deeper labyrinth trophoblast, S. Typhimurium Delta aroA bacteria localized primarily to the decidua. This correlated with the widespread placental necrosis accompanied by neutrophil infiltration evoked by the S. Typhimurium WT bacteria. Thus, the ability of Salmonella to localize to deeper layers of the placenta and the nature of inflammation triggered by the pathogen, rather than bacterial burden, profoundly influenced placental integrity and host survival.