Klebsiella oxytoca bacteremia-causal relationship to symptomatic colitis?

A Case of Co-infection Due to Shigella flexneri Colitis Resulting in Bacillus Septic Shock in an Immunocompetent Patient

Shigella flexneri (S. flexneri) is a facultatively anaerobic gram-negative bacterium that is a member of Enterobacteriaceae. The bacterium has been known to cause mild symptoms, such as diarrhea, to more severe diseases such as hemorrhagic colitis. Fortunately, such instances of severe diseases are rare. Nevertheless, even though S. flexneri is a more benign bacterium of the Shigella genus when compared to Shigella dysenteriae, this doesn't mean that it should be neglected. In fact, the ability of this microorganism to cause inflammation of the colon or colitis and disrupt tissue architecture can allow other organisms that would otherwise be benign to cause severe complications, hence allowing said organisms to be opportunistic. Here, we would like to present a case of S. flexneri colitis resulting in bacillus bacteremia and eventually causing an inappropriate physiological host response leading to hypotension, systematic organ failure, etc., also known as septic shock. The pathogenesis and treatment of this patient will also be discussed.

Oat-based postbiotics ameliorate high-sucrose induced liver injury and colitis susceptibility by modulating fatty acids metabolism and gut microbiota

High-sucrose (HS) consumption leads to metabolic disorders and increases susceptibility to colitis. Postbiotics hold great potentials in combating metabolic diseases and offer advantages in safety and processability, compared with living probiotics. We developed innovative oat-based postbiotics and extensively explored how they could benefit in rats with long-term high-sucrose consumption. The postbiotics fermented with Lactiplantibacillus plantarum (OF-1) and OF-5, the one fermented with the optimal selection of five probiotics (i.e., L. plantarum, Limosilactobacillus reuteri, Lacticaseibacillus rhamnosus, Lactobacillus acidophilus, and Bifidobacterium lactis) alleviated HS induced liver injury, impaired fatty acid metabolism and inflammation through activating AMPK/SREBP-1c pathways. Moreover, oat-based postbiotics restored detrimental effects of HS on fatty acid profiles in liver, as evidenced by the increases in polyunsaturated fatty acids and decreases in saturated fatty acids, with OF-5 showing most pronounced effects. Furthermore, oat-based postbiotics prevented HS exacerbated susceptibility to dextran sodium sulfate caused colitis and reconstructed epithelial tight junction proteins in colons. Oat-based postbiotics, in particular OF-5 notably remodeled gut microbiota composition, e.g., enriching the relative abundances of Akkermansia, Bifidobacterium, Alloprevotella and Prevotella, which may play an important role in the liver-colon axis responsible for improvements of liver functions and reduction of colitis susceptibility. The heat-inactivated probiotics protected against HS-induced liver and colon damage, but such effects were less pronounced compared with oat-based postbiotics. Our findings emphasize the great value of oat-based postbiotics as nutritional therapeutics to combat unhealthy diet induced metabolic dysfunctions.

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.

Persistent Systemic Microbial Translocation, Inflammation, and Intestinal Damage During Clostridioides difficile Infection

BACKGROUND

Clostridioides difficile infection (CDI) might be complicated by the development of nosocomial bloodstream infection (n-BSI). Based on the hypothesis that alteration of the normal gut integrity is present during CDI, we evaluated markers of microbial translocation, inflammation, and intestinal damage in patients with CDI.

METHODS

Patients with documented CDI were enrolled in the study. For each subject, plasma samples were collected at T0 and T1 (before and after CDI therapy, respectively), and the following markers were evaluated: lipopolysaccharide-binding protein (LPB), EndoCab IgM, interleukin-6, intestinal fatty acid binding protein (I-FABP). Samples from nonhospitalized healthy controls were also included. The study population was divided into BSI+/BSI- and fecal microbiota transplantation (FMT) +/FMT- groups, according to the development of n-BSI and the receipt of FMT, respectively.

RESULTS

Overall, 45 subjects were included; 8 (17.7%) developed primary n-BSI. Markers of microbial translocation and intestinal damage significantly decreased between T0 and T1, however, without reaching values similar to controls (P < .0001). Compared with BSI-, a persistent high level of microbial translocation in the BSI+ group was observed. In the FMT+ group, markers of microbial translocation and inflammation at T1 tended to reach control values.

CONCLUSIONS

CDI is associated with high levels of microbial translocation, inflammation, and intestinal damage, which are still present at clinical resolution of CDI. The role of residual mucosal perturbation and persistence of intestinal cell damage in the development of n-BSI following CDI, as well as the possible effect of FMT in the restoration of mucosal integrity, should be further investigated.

Is Clostridium difficile infection a risk factor for subsequent bloodstream infection?

BACKGROUND

Clostridium difficile infection (CDI) is a common nosocomial diarrheal illness increasingly associated with mortality in United States. The underlying factors and mechanisms behind the recent increases in morbidity from CDI have not been fully elucidated. Murine models suggest a mucosal barrier breakdown leads to bacterial translocation and subsequent bloodstream infection (BSI). This study tests the hypothesis that CDI is associated with subsequent BSI in humans.

METHODS

We conducted a retrospective cohort study on 1132 inpatients hospitalized >72 h with available stool test results for toxigenic C. difficile. The primary outcome was BSI following CDI. Secondary outcomes included 30-day mortality, colectomy, readmission, and ICU admission. Unadjusted and adjusted logistic regression models were developed.

RESULTS

CDI occurred in 570 of 1132 patients (50.4%). BSI occurred in 86 (7.6%) patients. Enterococcus (14%) and Klebsiella (14%) species were the most common organisms. Patients with BSI had higher comorbidity scores and were more likely to be male, on immunosuppression, critically ill, and have a central venous catheter in place. Of the patients with BSI, 36 (42%) had CDI. CDI was not associated with subsequent BSI (OR 0.69; 95% CI 0.44-1.08; P = 0.103) in unadjusted analysis. In multivariable modeling, CDI appeared protective against subsequent BSI (OR 0.57; 95% CI 0.34-0.96; P = 0.036). Interaction modeling suggests a complicated relationship among CDI, BSI, antibiotic exposure, and central venous catheter use.

CONCLUSIONS

In this cohort of inpatients that underwent testing for CDI, CDI was not a risk factor for developing subsequent BSI.