Comparison of microbiological profile of enterotoxigenic Bacteroides fragilis (ETBF) isolates from subjects with colorectal cancer (CRC) or intestinal pre-cancerous lesions versus healthy individuals and evaluation of environmental factors involved in intestinal dysbiosis

OBJECTIVE

The aim of this study was to analyze enterotoxigenic Bacteroides fragilis (ETBF) isolates from colorectal biopsies of subjects with a histological analysis positive for colorectal cancer (CRC), pre-cancerous lesions (pre-CRC) or with a healthy intestinal tissue and to evaluate the environmental factors that may not only concur to CRC development but may also affect gut microbiota composition.

METHODS

ETBF isolates were typed using the ERIC-PCR method, while PCR assays were performed to investigate the bft alleles, the B. fragilis pathogenicity island (BFPAI) region and the cepA, cfiA and cfxA genes. Susceptibility to antibiotics was tested using the agar dilution method. Environmental factors that could play a role in promoting intestinal dysbiosis were evaluated throughout a questionnaire administered to the subjects enrolled.

RESULTS

Six different ERIC-PCR types were identified. The type denominated C in this study was the most prevalent, in particular among the biopsies of subjects with pre-CRC, while an isolate belonging to a different type, denominated F, was detected in a biopsy from a subject with CRC. All the ETBF isolates from pre-CRC or CRC subjects had a B. fragilis pathogenicity island (BFPAI) region pattern I, while those from healthy individuals showed also different patterns. Furthermore, 71% of isolates from subjects with pre-CRC or CRC were resistant to two or more classes of antibiotics vs 43% of isolates from healthy individuals. The B. fragilis toxin BFT1 was the most frequently detected in this study, confirming the constant circulation of this isoform strains in Italy. Interestingly, BFT1 was found in 86% of the ETBF isolates from patients with CRC or pre-CRC, while the BFT2 was prevalent among the ETBF isolates from healthy subjects. No substantial differences based on sex, age, tobacco and alcohol consumption were observed between healthy and non-healthy individuals included in this study, while most of the subjects with CRC or pre-CRC lesions were subjected to pharmacological therapy (71%) and showed a body mass index (BMI) that falls within the overweight range (86%).

CONCLUSIONS

Our data suggest that some types of ETBF seem to better adapt and colonize the human gut and that the selective pressure exerted by factors related to lifestyle, such as pharmacological therapy and weight, could facilitate their persistence in the gut and their possible involvement in CRC development.

Clostridioides difficile in Pigs and Dairy Cattle in Northern Italy: Prevalence, Characterization and Comparison between Animal and Human Strains

It has been observed that novel strains of Clostridioides difficile can rapidly emerge and move between animal and human hosts. The aim of this study was to investigate the prevalence of C. difficile in pigs and dairy cattle in northern Italy and to characterize and compare C. difficile animal strains with those from patients from the same geographical area. The C. difficile strains were isolated from animals from farms and slaughterhouses (cross-sectional studies) and from neonatal animals with enteric disorders in routine diagnostic investigations (passive surveillance). Samples positive for C. difficile were found in 87% of the pig farms and in 40% of the cattle farms involved in the cross-sectional studies, with a 20% prevalence among suckling piglets and 6.7% prevalence in neonatal calves, with no significant difference between animals with and without diarrheal symptoms. The prevalence of C. difficile in older animal categories was significantly lower. This result suggests that young age is an important risk factor for C. difficile colonization. In cross-sectional studies at slaughterhouses, in both the heavy pigs and dairy cows examined, only 2% of the intestinal content samples were positive for C. difficile and no contamination was found on the surface of the carcasses. Considering passive surveillance, the prevalence rates of positive samples were 29% in piglets and 1.4% in calves. Overall, 267 strains of animal origin and 97 from humans were collected. In total, 39 ribotypes (RTs) were identified, with RT 078 and RT 018 being predominant among animals and humans, respectively. Several RTs overlapped between animals and patients. In particular, RT 569 was identified as an emergent type in our country. Resistance to erythromycin and moxifloxacin was widely diffused among C. difficile strains, regardless of origin. This study supports C. difficile as a pathogen of one-health importance and highlights the need for a collaborative approach between physicians and veterinarians to control and prevent infections that are able to cross species and geographical barriers.

Fine needle aspiration of the liver

A total of 81 transhepatic fine needle aspiration (FNA) biopsies were performed on 78 patients to rule out focal or diffuse neoplastic disease; 87.6% were performed with ultrasound guidance, 6.1% with CT guidance, 3.7% intraoperatively and 1 using fluoroscopy during percutaneous transhepatic cholangiography. Smears of the aspirated samples were cytologically evaluated with clinical and radiologic correlation; in addition, histologic examination of cell blocks was performed in 46% of the cases, ultrastructural examination in 34% of the cases and peroxidase-antiperoxidase staining in 3 cases. Ultrastructural definition of the type of malignancy was possible in 24 cases (29%). Minor complications in two patients were pain and tenderness at the puncture site. The sensitivity for malignancy was 91%, the specificity was 100%, the predictive value of positive results was 100%, and the predictive value of negative results was 73%. This series demonstrates that FNA biopsy with ultrasound guidance can provide an accurate diagnosis of malignancy and may preempt a lengthy workup in the search for a primary tumor.

Fine needle aspiration of the pancreas. A five-year experience

Forty fine needle aspiration (FNA) biopsies of the pancreas were performed on 37 patients with a radiologic suspicion of malignancy; 32 aspirations were guided by ultrasound, 2 were guided by CT, and 6 were obtained intraoperatively. A pathologist read a rapid-stained smear of the initial aspirate as the procedure was performed and triaged specimens for routine cytologic, cell block and ultrastructural study in solid lesions plus carcinoembryonic antigen (CEA) assay and amylase study in cystic lesions. Purulent material was studied by gram staining and culture. The overall sensitivity in the series was 81%, with a specificity of 100%. No complications were noted. Ultrastructural examination improved the diagnostic accuracy in two cases. Assays for CEA and amylase in "cyst fluids" differentiated true cysts and cystadenocarcinoma from pseudocysts. Maximum utilization of the material aspirated was useful in diagnosing the etiology of solid and cystic pancreatic masses.

Carcinoembryonic antigen in effusions. A diagnostic adjunct to cytology

A total of 189 effusion specimens (100 benign and 89 malignant) submitted for cytologic examination were assayed for carcinoembryonic antigen (CEA) by an enzyme immunoassay to determine whether the addition of CEA evaluation to cytologic study would improve the diagnostic accuracy for the detection of malignancy. The sensitivity and specificity were 78% and 90%, respectively, for a cytologic diagnosis of malignancy and 68% and 99%, respectively, for a positive CEA (greater than 5 ng/mL). CEA assay was negative in the most common epithelial malignancies of the female genital tract (15 of 17 cases), mesotheliomas (5), lymphomas (7) and alveolar-cell carcinoma of lung (1). CEA assay was positive in 55 of 89 cases of malignancy, including 14 cases with cytologically negative malignant effusions. The CEA assay sensitivity for lung carcinoma (95% for adenocarcinoma, 100% for oat-cell carcinoma and 100% for carcinosarcoma), breast carcinoma (95%), and gastrointestinal carcinoma (100%) were all over 90%. No significant difference in the levels of CEA was noted between gastrointestinal and lung adenocarcinomas. Oat-cell carcinomas and squamous-cell carcinomas had lower values. In cases of an effusion with an unknown primary, an elevated CEA in the fluid is diagnostic of metastatic carcinoma arising from the breast, lung or gastrointestinal tract.