Unexpectedly High Prevalence of Cystoisospora belli Infection in Acalculous Gallbladders of Immunocompetent Patients

Abstract

ObjectivesIndications for cholecystectomy have changed dramatically over the past three decades. Cystoisospora belli has been reported in cholecystectomy specimens of immunocompetent patients. The present study was designed to determine the prevalence and clinical association of C belli in the gallbladder.MethodsThe study included retrospective review of cholecystectomy specimens (n = 401) removed for various indications, and a prospective cohort of cholecystectomy specimens (n = 22) entirely submitted for histologic evaluation. Correlations of presence of C belli with age, sex, clinical indication, and abnormalities of preoperative laboratory values were assessed by Fisher exact test.ResultsC belli was identified in 39/401 (9.7%) of the retrospective cohort, and 6/22 (27.3%) of the entirely submitted specimens. The presence of C belli showed no correlation with age, sex, clinical indication, or laboratory abnormalities.ConclusionsC belli resides in a latent state in the gallbladder and may be best considered a commensal organism.

Cystoisospora belliinfections in humans: the past 100 years

“…After a review of these reports, it became clear that details regarding C. belli developmental stages were lacking. Additionally, non-protozoal structures in the gallbladder of patients that were initially identified as C. belli (Lai et al ., 2016; Martelli and Lee, 2016; Akateh et al ., 2018; Noor et al ., 2019) are now considered artefacts. Therefore, an intensive search was made to identify the developmental stages of C. belli in the duodenum and common bile duct of two patients reported previously (Walther and Topazian, 2009; Swanson et al ., 2018).…”

Comparison of Two Real-Time PCR Assays Targeting Ribosomal Sequences for the Identification of Cystoisospora belli in Human Stool Samples

“…have been detected in primates in Ghana, but their role in transmission remains uncertain [ 15 ]. After infection, the parasites can be found in the epithelium of the intestines, the bile duct and the gallbladder [ 1 , 16 , 17 ]. In particular for the latter location, however, histological misidentifications have been reported as well [ 18 , 19 ].…”

Pitfalls in Morphologic Diagnosis of Pathogens: Lessons Learned From the Pseudo-Cystoisospora Epidemic

“…In the gallbladder, they are characteristically associated with epithelial injury or inflammation, lack of distinct vacuoles, and show negative staining by Alcian blue. 17 Thanatosomes have mostly a membrane-bound ultrastructure in contrast to the non-membrane bound fibrillary aggregates seen in inclusions. 27 Some groups have also suggested the possibility of abortive infection by a related animal species of the organism.…”

“…This was followed by multiple publications, abstract presentations at USCAP (United States and Canadian Academy of Pathology), and Twitter feeds including studies on pediatric cholecystectomies. 11-17 The majority of the studies reported an increased incidence of these organisms in acalculous cholecystectomies. Among acalculous cholecystectomies, no increased occurrence was noted in biliary dyskinesia.…”

“…1-7 Within the last 5 years, multiple groups have reported parasite infestation of the gallbladder in immunocompetent patients, especially in acalculous cholecystitis. 8-17 This led to an increased screening of gallbladder specimens for the organism by the pathologist and antibiotic treatment in some of the diagnosed patients. However, recently a few groups have shown at a molecular and ultrastructural level that these are inclusions rather than actual organisms.…”