The Risk of Subsequent Deep Vein Thrombosis and Pulmonary Embolism in Patients with Nontyphoidal Salmonellosis: A Nationwide Cohort Study

The purpose of this study was to evaluate the deep vein thrombosis (DVT) and pulmonary embolism (PE) risk among patients with a diagnosis of nontyphoidal salmonellosis (NTS) in an Asian population. The risk was analyzed in a cohort of 17,855 patients newly diagnosed with NTS and 71,420 individuals without NTS using a hospitalization claim dataset. Both groups were matched by age, sex, and index date as an original analysis. A Cox proportional-hazards regression model was applied to estimate the risk of DVT and PE, accounting for any competing event (death). With a follow-up of 4.94 (±3.93) years in the NTS group and 6.30 (±3.67) years in the non-NTS group, the adjusted subhazard ratios (SHRs) of DVT and PE were 1.83 (95% CI 1.44–2.31) and 1.84 (95% CI 1.30–2.60). The NTS group had an increased risk of DVT and PE compared with the control group in all of the age subgroups. Stratified analyses showed that patients aged 18–39 years in the NTS group had significantly higher DVT and PE risks compared with patients of the same age in the non-NTS group (aHR, 5.95; 95% CI, 2.22–15.91 for DVT; aHR 6.72; 95% CI, 2.23–20.30 for PE). The P-value for interaction between age and exposure of NTS is <0.001 for DVT and 0.004 for PE in our sub-group analyses. The findings were cross-validated by a re-analysis with propensity score matching (PSM), and that revealed consistent results. Despite of low absolute risk, clinicians should be aware that patients with an NTS hospitalization history is at increased risk for VTE especially when assessing patients coincident with other VTE risk factors.

Understanding Infection-Induced Thrombosis: Lessons Learned From Animal Models

Thrombosis is a common consequence of infection that is associated with poor patient outcome. Nevertheless, the mechanisms by which infection-associated thrombosis is induced, maintained and resolved are poorly understood, as is the contribution thrombosis makes to host control of infection and pathogen spread. The key difference between infection-associated thrombosis and thrombosis in other circumstances is a stronger inflammation-mediated component caused by the presence of the pathogen and its products. This inflammation triggers the activation of platelets, which may accompany damage to the endothelium, resulting in fibrin deposition and thrombus formation. This process is often referred to as thrombo-inflammation. Strikingly, despite its clinical importance and despite thrombi being induced to many different pathogens, it is still unclear whether the mechanisms underlying this process are conserved and how we can best understand this process. This review summarizes thrombosis in a variety of models, including single antigen models such as LPS, and infection models using viruses and bacteria. We provide a specific focus on Salmonella Typhimurium infection as a useful model to address all stages of thrombosis during infection. We highlight how this model has helped us identify how thrombosis can appear in different organs at different times and thrombi be detected for weeks after infection in one site, yet largely be resolved within 24 h in another. Furthermore, we discuss the observation that thrombi induced to Salmonella Typhimurium are largely devoid of bacteria. Finally, we discuss the value of different therapeutic approaches to target thrombosis, the potential importance of timing in their administration and the necessity to maintain normal hemostasis after treatment. Improvements in our understanding of these processes can be used to better target infection-mediated mechanisms of thrombosis.

Salmonella enterica Serovar Panama, an Understudied Serovar Responsible for Extraintestinal Salmonellosis Worldwide

In recent years nontyphoidal Salmonella has emerged as one of the pathogens most frequently isolated from the bloodstream in humans. Only a small group of Salmonella serovars cause this systemic infection, known as invasive nontyphoidal salmonellosis. Here, we present a focused minireview on Salmonella enterica serovar Panama, a serovar responsible for invasive salmonellosis worldwide. S Panama has been linked with infection of extraintestinal sites in humans, causing septicemia, meningitis, and osteomyelitis. The clinical picture is often complicated by antimicrobial resistance and has been associated with a large repertoire of transmission vehicles, including human feces and breast milk. Nonhuman sources of S Panama involve reptiles and environmental reservoirs, as well as food animals, such as pigs. The tendency of S Panama to cause invasive disease may be linked to certain serovar-specific genetic factors.

Rothia mucilaginosa pneumonia diagnosed by quantitative cultures and intracellular organisms of bronchoalveolar lavage in a lymphoma patient

Rothia mucilaginosa is a gram-positive coccus of the family Micrococcaceae. R. mucilaginosa is considered a part of the normal flora of the human oropharynx and upper respiratory tract and lower respiratory tract infections attributable to R. mucilaginosa are not frequent. We present a case of pneumonia, in which the R. mucilaginosa infection was diagnosed by quantitative cultures of a bronchoalveolar lavage (BAL) specimen. A 46-yr-old woman with B lymphoblastic lymphoma was admitted to the hospital for scheduled chemotherapy. Her chest computed tomography (CT) scan revealed bilateral multifocal nodular and patchy consolidation in both lungs. Investigation of the BAL specimen revealed that 7% of leukocytes had intracellular gram-positive cocci. The quantitative cultures of the BAL specimen grew mucoid, non-hemolytic, and grayish convex colonies on blood agar at a count of approximately 200,000 colony-forming units/mL. The colonies were identified as R. mucilaginosa. The patient was empirically treated with levofloxacin for 7 days, after which findings on the chest radiograph and CT scan improved. She was discharged with improvement on hospital day 46. To our knowledge, this is the first report of R. mucilaginosa pneumonia diagnosed in Korea. Quantitative culture of BAL specimen and examination of intracellular organisms are crucial for assessing the clinical significance of R. mucilaginosa recovered from the lower respiratory tract.