Acute intestinal ischemia in patients with COVID-19: single-centre experience and literature review

OBJECTIVE

Acute Intestinal ischemia (AII) may involve the small and/or large bowel after any process affecting intestinal blood flow. COVID-19-related gastrointestinal manifestations, including AII, have been attributed to pharmacologic effects, metabolic disorders in ICU patients and other opportunistic colonic pathogens. AII in COVID-19 patients may be due also to "viral enteropathy" and  SARS-CoV-2-induced small vessel thrombosis. A critical appraisal of personal experience regarding COVID-19 and AII was carried out comparing this with a systematic literature review of published series.

PATIENTS AND METHODS

  A retrospective observational clinical cohort study and a systematic literature review including only COVID-19 positive patients with acute arterial or venous intestinal ischemia were performed. The primary endpoint of the study was the mortality rate. Secondary endpoints were occurrence of major complications and length of hospital stay.

RESULTS

Patient mean age was 62.9±14.9, with a prevalence of male gender (23 male, 72% vs. 9 female, 28%). The mean Charlson Comorbidity Index was 3.1±2.7. Surgery was performed in 24/32 patients (75.0%), with a mean delay time from admission to surgery of 6.0 ±5.6 days. Small bowel ischemia was confirmed to be the most common finding at surgical exploration (22/24, 91.7%). Acute abdomen at admission to the ED (Group 1) was observed in 10 (31.2%) cases, while 16 (50%) patients developed an acute abdomen condition during hospitalization (Group 2) for SARS-CoV-2 infection.

CONCLUSIONS

Our literature review showed how intestinal ischemia in patients with SARS-CoV-2 has been reported all over the world. The majority of the patients have a high CCI with multiple comorbidities, above all hypertension and cardiovascular disease. GI symptoms were not always present at the admission. A high level of suspicion for intestinal ischemia should be maintained in COVID-19 patients presenting with GI symptoms or with incremental abdominal pain. Nevertheless, a prompt thromboelastogram and laboratory test may confirm the need of improving and fastening the use of anticoagulants and trigger an extended indication for early abdominal CECT in patients with suggestive symptoms or biochemical markers of intestinal ischemia.

A deep-sea bacterium related to coastal marine pathogens

Evolution of virulence traits from adaptation to environmental niches other than the host is probably a common feature of marine microbial pathogens, whose knowledge might be crucial to understand their emergence and pathogenetic potential. Here, we report genome sequence analysis of a novel marine bacterial species, Vibrio bathopelagicus sp. nov., isolated from warm bathypelagic waters (3309 m depth) of the Mediterranean Sea. Interestingly, V. bathopelagicus sp. nov. is closely related to coastal Vibrio strains pathogenic to marine bivalves. V. bathopelagicus sp. nov. genome encodes genes involved in environmental adaptation to the deep-sea but also in virulence, such as the R5.7 element, MARTX toxin cluster, Type VI secretion system and zinc-metalloprotease, previously associated with Vibrio infections in farmed oysters. The results of functional in vitro assays on immunocytes (haemocytes) of the Mediterranean mussel Mytilus galloprovincialis and the Pacific oyster Crassostrea gigas, and of the early larval development assay in Mytilus support strong toxicity of V. bathopelagicus sp. nov. towards bivalves. V. bathopelagicus sp. nov., isolated from a remote Mediterranean bathypelagic site, is an example of a planktonic marine bacterium with genotypic and phenotypic traits associated with animal pathogenicity, which might have played an evolutionary role in the origin of coastal marine pathogens.

Aquatic reservoir of Vibrio cholerae in an African Great Lake assessed by large scale plankton sampling and ultrasensitive molecular methods

The significance of large tropical lakes as environmental reservoirs of Vibrio cholerae in cholera endemic countries has yet to be established. By combining large scale plankton sampling, microbial culture and ultrasensitive molecular methods, namely Droplet Digital PCR (ddPCR) and targeted genomics, the presence of Vibrio cholerae was investigated in a 96,600 L volume of surface water collected on a 322 nautical mile (596 km) transect in Lake Tanganyika. V. cholerae was detected and identified in a large area of the lake. In contrast, toxigenic strains of V. cholerae O1 or O139 were not detected in plankton samples possibly in relation to environmental conditions of the lake ecosystem, namely very low salinity compared to marine brackish and coastal environments. This represents to our knowledge, the largest environmental study to determine the role of tropical lakes as a reservoir of V. cholerae.

Shift in Immune Parameters After Repeated Exposure to Nanoplastics in the Marine Bivalve Mytilus

Bivalves are widespread in coastal environments subjected to a wide range of environmental fluctuations: however, the rapidly occurring changes due to several anthropogenic factors can represent a significant threat to bivalve immunity. The mussel Mytilus spp. has extremely powerful immune defenses toward different potential pathogens and contaminant stressors. In particular, the mussel immune system represents a significant target for different types of nanoparticles (NPs), including amino-modified nanopolystyrene (PS-NH₂) as a model of nanoplastics. In this work, the effects of repeated exposure to PS-NH₂ on immune responses of Mytilus galloprovincialis were investigated after a first exposure (10 μg/L; 24 h), followed by a resting period (72-h depuration) and a second exposure (10 μg/L; 24 h). Functional parameters were measured in hemocytes, serum, and whole hemolymph samples. In hemocytes, transcription of selected genes involved in proliferation/apoptosis and immune response was evaluated by qPCR. First exposure to PS-NH₂ significantly affected hemocyte mitochondrial and lysosomal parameters, serum lysozyme activity, and transcription of proliferation/apoptosis markers; significant upregulation of extrapallial protein precursor (EPp) and downregulation of lysozyme and mytilin B were observed. The results of functional hemocyte parameters indicate the occurrence of stress conditions that did not however result in changes in the overall bactericidal activity. After the second exposure, a shift in hemocyte subpopulations, together with reestablishment of basal functional parameters and of proliferation/apoptotic markers, was observed. Moreover, hemolymph bactericidal activity, as well as transcription of five out of six immune-related genes, all codifying for secreted proteins, was significantly increased. The results indicate an overall shift in immune parameters that may act as compensatory mechanisms to maintain immune homeostasis after a second encounter with PS-NH₂.

Dynamics of the Pacific oyster pathobiota during mortality episodes in Europe assessed by 16S rRNA gene profiling and a new target enrichment next-generation sequencing strategy

Infectious agents such as the bacteria Vibrio aestuarianus or Ostreid herpesvirus 1 have been repeatedly associated with dramatic disease outbreaks of Crassostrea gigas beds in Europe. Beside roles played by these pathogens, microbial infections in C. gigas may derive from the contribution of a larger number of microorganisms than previously thought, according to an emerging view supporting the polymicrobial nature of bivalve diseases. In this study, the microbial communities associated with a large number of C. gigas samples collected during recurrent mortality episodes at different European sites were investigated by real-time PCR and 16SrRNA gene-based microbial profiling. A new target enrichment next-generation sequencing protocol for selective capturing of 884 phylogenetic and virulence markers of the potential microbial pathogenic community in oyster tissue was developed allowing high taxonomic resolution analysis of the bivalve pathobiota. Comparative analysis of contrasting C. gigas samples conducted using these methods revealed that oyster experiencing mortality outbreaks displayed signs of microbiota disruption associated with the presence of previously undetected potential pathogenic microbial species mostly belonging to genus Vibrio and Arcobacter. The role of these species and their consortia should be targeted by future studies aiming to shed light on mechanisms underlying polymicrobial infections in C. gigas.

Responses of Mytilus galloprovincialis to challenge with the emerging marine pathogen Vibrio coralliilyticus

Vibrio coralliilyticus has emerged as a coral pathogen of concern throughout the Indo-Pacific reef. The interest towards understanding its ecology and pathogenic potential has increased since V. coralliilyticus was shown to be strongly virulent also for other species; in particular, it represents a serious threat for bivalve aquaculture, being one of the most important emerging pathogen responsible for oyster larval mortalities worldwide. V. coralliilyticus has a tightly regulated temperature-dependent virulence and it has been related to mass mortalities events of benthic invertebrates also in the temperate northwestern Mediterranean Sea. However, no data are available on the effects of V. coralliilyticus in the mussel Mytilus galloprovincialis, the most abundant aquacultured species in this area. In this work, responses of M. galloprovincialis to challenge with V. coralliilyticus (ATCC BAA-450) were investigated. In vitro, short term responses of mussel hemocytes were evaluated in terms of lysosomal membrane stability, bactericidal activity, lysozyme release, ROS and NO production, and ultrastructural changes, evaluated by TEM. In vivo, hemolymph parameters were measured in mussels challenged with V. coralliilyticus at 24h p.i. Moreover, the effects of V. coralliilyticus on mussel early embryo development (at 48 hpf) were evaluated. The results show that both in vitro and in vivo, mussels were unable to activate immune response towards V. coralliilyticus, and that challenge mainly induced lysosomal stress in the hemocytes. Moreover, V. coralliilyticus showed a strong and concentration-dependent embryotoxicity. Overall, the results indicate that, although M. galloprovincialis is considered a resistant species to vibrio infections, the emerging pathogen V. coralliilyticus can represent a potential threat to mussel aquaculture.

ddPCR applied on archived Continuous Plankton Recorder samples reveals long-term occurrence of class 1 integrons and a sulphonamide resistance gene in marine plankton communities

Antibiotic resistance is a rising threat for human health. Although in clinical settings and terrestrial environments the rise of antibiotic resistant bacteria is well documented, their dissemination and spread in the marine environment, covering almost two-thirds of the Earth's surface, is still poorly understood. In this study, the presence and abundance of sulphonamide resistance gene (sul2) and class 1 integron-integrase gene (intI1), used as markers for the occurrence and spread of antibiotic resistance genes since the beginning of the antibiotic era, were investigated. Twenty-nine archived formalin-fixed samples, collected by the Continuous Plankton Recorder (CPR) survey in the Atlantic Ocean and North Sea from 1970 to 2011, were analysed using Droplet Digital PCR (ddPCR) applied for the first time on CPR samples. The two marker genes were present in a large fraction of the samples (48% for sul2 and 76% for intI1). In contrast, results from Real-Time PCR performed on the same samples greatly underestimate their occurrence (21% for sul2 and 52% for intI1). Overall, besides providing successful use of ddPCR for the molecular analysis of CPR samples, this study reveals long-term occurrence and spread of sul2 gene and class 1 integrons in the plankton-associated bacterial communities in the ocean.

Aneuploidies of chromosome 17 in breast cancer: Relative prevalence in a series of 170 patients from Córdoba, Argentina, studied with fluorescent in-situ hybridization (FISH)

e22195

Background: The amplification of HER-2 oncogen, located in 17q11.2–12, occurs in 20–30% of invasive breast cancer. Numerical anomalies of chromosome 17 are frequent findings in these patients, during the study of the amplification of HER-2 oncogen with FISH technique, though clinical implications are yet not defined. Objectives: To determine the presence of chromosome 17 aneuploidies in a series of patients with histological diagnosis of breast cancer and to correlate these data with amplification and overexpression of HER-2 oncogen. Methods: Samples of 170 patients included in paraffin were analyzed with FISH technique, using the PathVysion system. We analyzed the number of HER-2 oncogen specific signals and chromosome 17 centromere (CEP 17) signals. We followed the ASCO 2007 guidelines to evaluate FISH and immunohistochemical analysis (IHC). Criteria for aneuploidy: diploid at 1.5–2.25 average CEP 17 signals /cell; hyperdiploidy: values over 2.25 and hypodiploidy: lower than 1.5. Results: We found 73 cases of chromosome 17 aneuploidies (42.9%), 68/73 polysomies (93%) and 5/73 monosomies (7%). The monosomies were observed in 4/5 patients with HER-2 amplification. Polysomies occurred simultaneously with HER-2 amplification in 48% (35/73), 45% (33/73) were not amplified and 7% (5/73) were equivocal. FISH and IHC could be correlated in 136 patients: the higher percentage of polysomies observed corresponded to groups IHC+3/HER-2+ (46%) and IHC+2/HER- (29%). Polysomy 17 was detected in 3 cases IHC+3/HER-2-. Conclusions: The relative prevalence of chromosome 17 aneuploidy in our series was 43%. According to the literature, this finding in 3 patients IHC+3/HER-2- could be responsible for the overexpression of protein cerbB2. The clinical effect of chromosome 17 aneuploidy continues under study.

No significant financial relationships to disclose.