Tropheryma whipplei, a Potential Commensal Detected in Individuals Undergoing Routine Colonoscopy

Using Targeted Next-Generation Sequencing to Diagnose Severe Pneumonia Due to Tropheryma Whipplei and Human Metapneumovirus: A Case Report and Literature Review

Background

In addition to the well-known Whipple's disease (WD), Tropheryma Whipplei (TW) can also lead to acute pneumonia. There is no unified consensus on the susceptible population, pathogenesis, clinical manifestations, diagnostic criteria, and treatment options for TW pneumonia.

Clinical Presentation and Intervention

This is an elderly patient with multiple injuries caused by falling from a building, and was transferred to intensive care unit (ICU) for mechanical ventilation and empirical anti-infection treatment due to severe pneumonia, and then the results of targeted next-generation sequencing (tNGS) in patient's bronchoalveolar lavage fluid (BALF) suggested TW and human metapneumovirus (HMPV) infection, and after switching to anti-infective therapy for TW, the patient was successfully extubated and transferred out of the ICU.

Conclusion

This is the first case of using tNGS to diagnose severe pneumonia caused by TW and HMPV. We hope that our study can serve as a reference for the diagnosis and treatment of related cases in the future.

[Co-occurrence of Whipple's disease and hyperparathyroidism - coincidence or causal relationship?]

Whipple's disease is a rare infectious disease with multiple clinical manifestations. The disease is named after George Hoyt Whipple, who first recorded the illness in 1907 after conducting the autopsy of a 36-year-old man with weight loss, diarrhea, and arthritis. Under the microscope, Whipple discovered a rod-shaped bacterium in the patient's intestinal wall, which was not confirmed as a new bacterial species until 1992, when it was named Tropheryma whipplei.Recurrence of Whipple's disease can occur years after an initial diagnosis and often manifests with extraintestinal symptoms such as arthritides or skin efflorescences, years before a gastrointestinal complaint. However, the simultaneous occurrence of primary hyperparathyroidism in the present case is a hitherto unknown clinical picture and opens up new questions and perspectives in the context of diagnostics and therapy.

Contribution of PCR to Differential Diagnosis between Patients with Whipple Disease and Tropheryma whipplei Carriers

Differentiation between Whipple disease (WD) patients and patients carrying Tropheryma whipplei but suffering from disease other than WD ("carriers") remains complex. We aimed to evaluate T. whipplei PCR among patients with WD and carriers in a large cohort at our referral clinical microbiology laboratory. This is an observational retrospective cohort study, including all patients between 2008 and 2020 with at least one positive result for T. whipplei using the real-time PCR RealCycler TRWH-UX kit. A total of 233 patients were included: 197 were considered carriers, and 36 had WD. Among the WD patients, 32 underwent biopsies, of which 18 (56%) had a positive periodic acid-Schiff (PAS) staining. Among the 27 duodenal biopsy specimens, 13 (48%) were PAS positive. PCR results before antibiotic treatment were positive in both feces and saliva in 16/21 WD (76%) patients and 68/197 (35%) carriers (P < 0.001). Duodenal biopsy specimens yielded positive PCR in 20/22 (91%) WD patients and 27/72 (38%) carriers (P < 0.001). The cycle threshold (C_T) value detected in duodenal biopsy specimens from WD patients was significantly lower than that of carriers (P < 0.001), regardless of the PAS staining results. For a diagnosis of WD, duodenal PCR sensitivity and specificity at a C_T value below 30 were 52.4% and >99.9%, respectively. The high specificity of duodenal PCR with low C_T values may help confirming the diagnosis of WD, especially in patients with negative PAS results in digestive biopsy specimens, who represent half of all patients. A low PCR C_T value from a duodenal biopsy specimen provides valuable guidance, especially in patients with PAS-negative results.

Tropheryma whipplei Endocarditis: Case Presentation and Review of the Literature

Whipple’s disease is a rare infective condition, classically presenting with gastrointestinal manifestations. It is increasingly recognized as an important cause of culture-negative endocarditis. We present a case of Whipple’s endocarditis presenting with heart failure. A literature review identified 44 publications documenting 169 patients with Whipple’s endocarditis. The average age was 57.1 years. There is a clear sex predominance, with 85% of cases being male. Presenting symptoms were primarily articular involvement (52%) and heart failure (41%). In the majority of cases, the diagnosis was made on examination of valvular tissue. Preexisting valvular abnormalities were reported in 21%. The aortic valve was most commonly involved, and multiple valves were involved in 64% and 23% of cases, respectively. Antibiotic therapy was widely varied and included a ceftriaxone, trimethoprim, and sulfamethoxazole combination. The average follow-up was 20 months, and mortality was approximately 24%. Physician awareness is paramount in the diagnosis and management of this rare condition.

Development and first evaluation of a novel multiplex real-time PCR on whole blood samples for rapid pathogen identification in critically ill patients with sepsis

Molecular tests may enable early adjustment of antimicrobial therapy and be complementary to blood culture (BC) which has imperfect sensitivity in critically ill patients. We evaluated a novel multiplex real-time PCR assay to diagnose bloodstream pathogens directly in whole blood samples (BSI-PCR). BSI-PCR included 11 species- and four genus-specific PCRs, a molecular Gram-stain PCR, and two antibiotic resistance markers. We collected 5 mL blood from critically ill patients simultaneously with clinically indicated BC. Microbial DNA was isolated using the Polaris method followed by automated DNA extraction. Sensitivity and specificity were calculated using BC as reference. BSI-PCR was evaluated in 347 BC-positive samples (representing up to 50 instances of each pathogen covered by the test) and 200 BC-negative samples. Bacterial species-specific PCR sensitivities ranged from 65 to 100%. Sensitivity was 26% for the Gram-positive PCR, 32% for the Gram-negative PCR, and ranged 0 to 7% for yeast PCRs. Yeast detection was improved to 40% in a smaller set-up. There was no overall association between BSI-PCR sensitivity and time-to-positivity of BC (which was highly variable), yet Ct-values were lower for true-positive versus false-positive PCR results. False-positive results were observed in 84 (4%) of the 2200 species-specific PCRs in 200 culture-negative samples, and ranged from 0 to 6% for generic PCRs. Sensitivity of BSI-PCR was promising for individual bacterial pathogens, but still insufficient for yeasts and generic PCRs. Further development of BSI-PCR will focus on improving sensitivity by increasing input volumes and on subsequent implementation as a bedside test.

Clinical Manifestations, Treatment, and Diagnosis of Tropheryma whipplei Infections

Whipple's disease is a rare infectious disease that can be fatal if left untreated. The disease is caused by infection with Tropheryma whipplei, a bacterium that may be more common than was initially assumed. Most patients present with nonspecific symptoms, and as routine cultivation of the bacterium is not feasible, it is difficult to diagnose this infection. On the other hand, due to the generic symptoms, infection with this bacterium is actually quite often in the differential diagnosis. The gold standard for diagnosis used to be periodic acid-Schiff (PAS) staining of duodenal biopsy specimens, but PAS staining has a poor specificity and sensitivity. The development of molecular techniques has resulted in more convenient methods for detecting T. whipplei infections, and this has greatly improved the diagnosis of this often missed infection. In addition, the molecular detection of T. whipplei has resulted in an increase in knowledge about its pathogenicity, and this review gives an overview of the new insights in epidemiology, pathogenesis, clinical manifestations, diagnosis, and treatment of Tropheryma whipplei infections.