Causes of hematochezia and hemorrhagic antibiotic-associated colitis in children and adolescents

Gut Microbiota Dysbiosis in Suspected Food Protein Induced Proctocolitis-A Prospective Comparative Cohort Trial

OBJECTIVES

In infants with suspected food protein induced proctocolitis (sFPIP) only a minority of patients are finally diagnosed with the disease following diagnostic dietary intervention (DDI). There is a need for a pathophysiological explanation for the cause of hematochezia in the majority of sFPIP infants.

METHODS

We prospectively recruited infants with sFPIP and healthy controls. Fecal samples were collected at inclusion, week 4 (end of DDI in sFPIP), and week 8. For 16S rRNA sequencing (515F/806R) we used Illumina MiSeq sequencing system. Amplicon sequence variants were generated using Qiime2 and DADA2. Qiime diversity alpha and beta group comparisons and linear discriminant analysis effect size analysis was performed. For shotgun metagenomic analysis on species level we used KneadData and MetaPhlAn2.

RESULTS

Fourteen sFPIP infants were compared to 55 healthy infants. At inclusion overall microbial composition of sFPIP infants differed significantly from controls (weighted UniFrac; Pairwise PERMANOVA, P = 0.002, pseudo- F = 5.008). On genus level healthy infant microbiota was significantly enriched with Bifidobacterium ( B ) compared to sFPIP patients (linear discriminant analysis [LDA] = 5.5, P < 0.001, 31.3% vs 12.1%). sFPIP stool was significantly enriched by Clostridium sensu stricto 1 over controls (LDA = 5.3, P = 0.003, 3.5% vs 18.3%). DDI caused a significant and sustained increase of Bifidobacterium (LDA = 5.4, P = 0.048, 27.9%) in sFPIP infants. Species level analysis revealed significant reduction of abundance of B longum in sFPIP patients, which after DDI was reversed by B. species other than B longum .

CONCLUSIONS

We revealed a gut microbiota dysbiosis phenomenon in sFPIP infants. DDI induces a microbiota composition comparable to that of healthy infants. In most sFPIP infants hematochezia might be triggered by a gut microbiota dysbiosis phenomenon.

Blood Clots Per Rectum in a Pediatric Patient With Salmonella Enteritis: A Case Report

Infection is a common cause of hematochezia in children. While infectious diarrhea can present with bloody stools, it is rare to have the passage of frank blood clots per rectum in the pediatric population. This is a case of a seven-year-old male who presented with vomiting, diarrhea, severe abdominal pain, and passage of blood clots per rectum. As symptoms progressed, consideration of non-infectious causes was investigated and subsequently ruled out. The stool polymerase chain reaction (PCR) was positive for Salmonella species, while stool culture was negative for any enteropathogen. This report highlights the unusual occurrence of the passage of blood clots per rectum in a child with salmonella enterocolitis.

Hematochezia in children with acute diarrhea seeking emergency department care - a prospective cohort study

OBJECTIVES

Although the passage of blood in stools in children represents a medical emergency, children seeking emergency department (ED) care remain poorly characterized. Our primary objective was to compare clinical characteristics and etiologic pathogens in children with acute diarrhea with and without caregiver-reported hematochezia. Secondary objectives were to characterize interventions and resource utilization.

METHODS

We conducted a secondary analysis of the Alberta Provincial Pediatric EnTeric Infection TEam (APPETITE) database. Children <18 years presenting to two pediatric EDs within a 24-hour period and <7 days of symptoms were consecutively recruited.

RESULTS

Of 1,061 participants, 115 (10.8%) reported hematochezia at the enrollment visit at which time those with hematochezia, compared to those without, had more diarrheal episodes/24-hour period (9 vs. 6; difference: 2; 95% confidence interval [CI]: 2.0, 4.0; p < 0.001), and were less likely to have experienced vomiting (54.8% vs. 80.2%; difference: -25.4; 95% CI: -34.9, -16.0; p < 0.001). They were more likely to receive intravenous fluids (33.0% vs. 17.9%; difference: 15.2; 95% CI: 6.2, 24.1; p < 0.001) and require repeat health care visits (45.5% vs. 34.7%; difference: 10.7; 95% CI: 0.9, 20.6; p = 0.03). A bacterial pathogen was identified in 33.0% of children with hematochezia versus 7.9% without (difference: 25.1; 95% CI: 16.3, 33.9; p < 0.001); viruses were detected in 31.3% of children with hematochezia compared to 72.3% in those without (difference: -41.0%, 95% CI: -49.9, -32.1; p < 0.001).

CONCLUSION

In children with acute diarrhea, caregiver report of hematochezia, compared to the absence of hematochezia, was associated with more diarrheal but fewer vomiting episodes, and greater resource consumption. The former group of children was also more likely to have bacteria detected in their stool.

Klebsiella oxytoca Complex: Update on Taxonomy, Antimicrobial Resistance, and Virulence

Klebsiella oxytoca is actually a complex of nine species-Klebsiella grimontii, Klebsiella huaxiensis, Klebsiella michiganensis, K. oxytoca, Klebsiella pasteurii, Klebsiella spallanzanii, and three unnamed novel species. Phenotypic tests can assign isolates to the complex, but precise species identification requires genome-based analysis. The K. oxytoca complex is a human commensal but also an opportunistic pathogen causing various infections, such as antibiotic-associated hemorrhagic colitis (AAHC), urinary tract infection, and bacteremia, and has caused outbreaks. Production of the cytotoxins tilivalline and tilimycin lead to AAHC, while many virulence factors seen in Klebsiella pneumoniae, such as capsular polysaccharides and fimbriae, have been found in the complex; however, their association with pathogenicity remains unclear. Among the 5,724 K. oxytoca clinical isolates in the SENTRY surveillance system, the rates of nonsusceptibility to carbapenems, ceftriaxone, ciprofloxacin, colistin, and tigecycline were 1.8%, 12.5%, 7.1%, 0.8%, and 0.1%, respectively. Resistance to carbapenems is increasing alarmingly. In addition to the intrinsic bla_OXY, many genes encoding β-lactamases with varying spectra of hydrolysis, including extended-spectrum β-lactamases, such as a few CTX-M variants and several TEM and SHV variants, have been found. bla_KPC-2 is the most common carbapenemase gene found in the complex and is mainly seen on IncN or IncF plasmids. Due to the ability to acquire antimicrobial resistance and the carriage of multiple virulence genes, the K. oxytoca complex has the potential to become a major threat to human health.

Weak Microbial Metabolites: a Treasure Trove for Using Biomimicry to Discover and Optimize Drugs

For decades, traditional drug discovery has used natural product and synthetic chemistry approaches to generate libraries of compounds, with some ending as promising drug candidates. A complementary approach has been to adopt the concept of biomimicry of natural products and metabolites so as to improve multiple drug-like features of the parent molecule. In this effort, promiscuous and weak interactions between ligands and receptors are often ignored in a drug discovery process. In this Emerging Concepts article, we highlight microbial metabolite mimicry, whereby parent metabolites have weak interactions with their receptors that then have led to discrete examples of more potent and effective drug-like molecules. We show specific examples of parent-metabolite mimics with potent effects in vitro and in vivo. Furthermore, we show examples of emerging microbial ligand-receptor interactions and provide a context in which these ligands could be improved as potential drugs. A balanced conceptual advance is provided in which we also acknowledge potential pitfalls-hyperstimulation of finely balanced receptor-ligand interactions could also be detrimental. However, with balance, we provide examples of where this emerging concept needs to be tested. SIGNIFICANCE STATEMENT: Microbial metabolite mimicry is a novel way to expand on the chemical repertoire of future drugs. The emerging concept is now explained using specific examples of the discovery of therapeutic leads from microbial metabolites.

Biofilm Formation and Virulence Determinants of Klebsiella oxytoca Clinical Isolates from Patients with Colorectal Cancer

OBJECTIVE

Biofilm formation has made the therapy of bacterial infections more difficult. The objective our study was assessment of pan-drug-resistant (PDR) Klebsiella oxytoca pathogenicity and virulence factors causing AAHC in patients with colorectal cancer (CRC).

MATERIALS AND METHODS

Among a total of 300 healthy and 300 patients with antibiotic-associated hemorrhagic colitis (AAHC) and CRC, 200 K. oxytoca were identified during May 2015-January 2019. The virulence properties and biofilm formation among the isolates were investigated by phenotypic, PCR, and real-time PCR (RT-qPCR) techniques.

RESULTS

The bla_CTX-M1 (20%), bla_SHV (11%), bla_TEM1 (33%), and AmpC encoding CIT (2%) ESBL genes, carbapenemase-encoding genes blaIM (4%) and bla_OXA-48 (2%), and colistin-resistant mcr-1 gene (2.5%) were detected. The virulence-encoding genes including fimA (80%), pilQ (100%), matB (100%), mrkA (80%), and npsB (100%) were amplified. Therefore, PDR K. oxytoca containing adhesins and toxin-encoding genes with ability of biofilm formation causing AAHC and CRC were isolated. There was a significant difference between healthy and patients with CRC regarding the presence of K. oxytoca (p = 00.221).

CONCLUSION

Bacterial enteric pathogens possibly play a role in CRC. Biofilm formation by K. oxytoca strains prevents the efficient infection elimination; therefore, rapid identification and control measure are chief requirements. Additionally, more investigations are necessary with this regard.