Stool cultures at the ICU: get rid of it!

Diarrhea don'ts: Reducing inappropriate stool cultures and ova and parasite testing for nosocomial diarrhea

BACKGROUND

Diarrhea that develops in patients after 72 hours of hospitalization is likely to have a nosocomial or iatrogenic etiology. Testing with stool cultures and stool ova and parasites (O&P) is not recommended. Our goal was to reduce this inappropriate testing within a large, urban safety-net hospital system.

METHODS

This was a quality improvement project. We created a best practice advisory (BPA) within the electronic medical record that fires when a stool culture or O&P order is placed 72 hours after admission for any immunocompetent patient. It states that stool testing is low yield and offers the option to remove the order. We measured weekly counts of stool culture and stool O&P orders pre- and postintervention. We also measured the BPA acceptance rate, the 24-hour stool testing reorder rate, and Clostridioides difficile infection rates. Data were analyzed using Welch tests as well as a quasi-experimental pre- and postintervention interrupted time series regression analysis.

RESULTS

Stool culture orders decreased by 24.4% (P < .001). There was a significant level difference and slope difference with linear regression. Five of the 11 hospitals had a significant reduction in stool culture orders. Stool O&P orders decreased by 18.2% (P < .01). Three of the 11 hospitals had a significant reduction in stool O&P orders.

CONCLUSIONS

Our intervention successfully reduced inappropriate stool testing within a large safety-net hospital system.

Minority report: the intestinal mycobiota in systemic infections

Compared to bacteria, fungi often exhibit a lower abundance and a higher temporal volatility in the intestinal microbiota. Analysis of fungi in the microbiota (mycobiota) faces technical limitations with tools that were originally developed for analyzing bacteria. Dysbiotic states of the intestinal mycobiota, often associated with disruption of the healthy bacterial microbiota, are characterized by overgrowth (domination) of specific fungal taxa and loss of diversity. Intestinal domination by Candida species has been shown to be a major source of Candida bloodstream infections. Fungal dysbiosis is also linked to the development and treatment response in non-fungal infections, for example Clostridioides difficile colitis and HIV. Further research is needed to define the contribution of intestinal mycobiota to human fungal and non-fungal infections.

Diarrhoea in critical care is rarely infective in origin, associated with increased length of stay and higher mortality

Diarrhoea, defined as > 3 loose or liquid stools per day, affects 9.7-41% of intensive care unit patients, negatively impacting on patient dignity, intensifying nursing workload and increasing morbidity. Its pathogenesis is poorly understood, but infective agents, intensive care unit therapies (such as enteral feed) and critical illness changes in the gut microbiome are thought to play a role. We analysed a consecutive cohort of 3737 patients admitted to a mixed general intensive care unit. Diarrhoea prevalence was lower than previously reported (5.3%), rarely infective in origin (6.5%) and associated with increased length of stay (median (inter-quartile range) 2.3 (1.0-5.0) days vs. 10 days (5.0-22.0), p < 0.001, sub-distribution hazard ratio 0.55 (95% CI 0.48-0.63), p < 0.001) and mortality (9.5% vs. 18.1%, p = 0.005, sub-distribution hazard ratio 1.20 (95% CI 0.79-1.81), p = 0.40), compared to patients without diarrhoea. In addition, 17.1% of patients received laxatives <24 h prior to diarrhoea onset. Further research on diarrhoea's pathogenesis in critical care is required; robust treatment protocols, investigation rationalisation and improved laxative prescribing may reduce its incidence and improve related outcomes.

Initial therapy affects duration of diarrhoea in critically ill patients with Clostridioides difficile infection (CDI)

Background

Critically ill patients in the intensive care unit (ICU) are at high risk for developing Clostridioides difficile infections (CDI). Risk factors predicting their mortality or standardized treatment recommendations have not been defined for this cohort. Our goal is to determine outcome and mortality associated risk factors for patients at the ICU with CDI by evaluating clinical characteristics and therapy regimens.

Methods

A retrospective single-centre cohort study. One hundred forty-four patients (0.4%) with CDI-associated diarrhoea were included (total 36.477 patients admitted to 12 ICUs from January 2010 to September 2015). Eight patients without specific antibiotic therapy were excluded, so 132 patients were analysed regarding mortality, associated risk factors and therapy regimens using univariate and multivariate regression.

Results

Twenty-eight-day mortality was high in patients diagnosed with CDI (27.3%) compared to non-infected ICU patients (9%). Patients with non CDI-related sepsis (n = 40/132; 30.3%) showed further increase in 28-day mortality (45%; p = 0.003). Initially, most patients were treated with a single CDI-specific agent (n = 120/132; 90.9%), either metronidazole (orally, 35.6%; or IV, 37.1%) or vancomycin (18.2%), or with a combination of antibiotics (n = 12/132; 9.1%). Patients treated with metronidazole IV showed significantly longer duration of diarrhoea > 5 days (p = 0.006). In a multivariate regression model, metronidazole IV as initial therapy was an independent risk factor for delayed clinical cure. Immunosuppressants (p = 0.007) during ICU stay lead to increased 28-day mortality.

Conclusion

Treatment of CDI with solely metronidazole IV leads to a prolonged disease course in critically ill patients.

A Two-Step Approach for Diagnosing Glutamate Dehydrogenase Genes by Conventional Polymerase Chain Reaction from Clostridium difficile Isolates

BACKGROUND

Clostridium difficile is the major causative agent of nosocomial antibiotic-associated colitis. The gold standard for C. difficile detection is stool culture followed by cytotoxic assay, although it is laborious and time-consuming. We developed a screening test based on a two-step conventional polymerase chain reaction (PCR) approach to detect gluD, the glutamate dehydrogenase (GDH) enzyme gene, which is a marker for screening of C. difficile. Targeting gluD comparing to the conserved stable genetic element of pathogenicity locus (PaLoc), with an accessory gene of Cdd3, was an effective method for the detection of this pathogen from patients with enterocolitis.

METHODS

Fresh fecal samples of the patients who were clinically suspicious for antibiotic-associated colitis were collected. Stool specimens were cultured on the cycloserine-cefoxitin fructose agar (CCFA) in an anaerobic condition, following alcohol shock treatment and enrichment in Clostridium difficile Brucella broth (CDBB). On confirmed colonies, PCR was carried out for detection of PaLoc subsidiary gene, Cdd3, and toxicogenic genes, tcdA and tcdB. The gluD that is GDH gene detection was performed by conventional PCR on the extracted DNA from 578 fresh stool samples.

RESULTS

57 (9.8%) strains of C. difficile were approved by conventional PCR for gluD and Cdd3 genes, in which 37 (6.4%) colonies had tcdA+/tcdB+ genotype, 2 (0.3%) tcdA+/tcdB-, 4 (0.7%) tcdA-/ tcdB+ and the remaining 14 (2.4%) colonies were tcdA and tcdB negative.

CONCLUSION

These results demonstrate that targeting gluD by PCR is quite promising for rapid detection of C. difficile from fresh fecal samples. Furthermore, the multiple-gene analysis for tcdA and tcdB assay proved a reliable approach for diagnosing of toxigenic strains among clinical samples.