Trends in the use of laboratory tests for the diagnosis of Clostridium difficile infection and association with incidence rates in Quebec, Canada, 2010-2014

The changing epidemiology of Clostridioides difficile infection and the NAP1/027 strain in two Québec hospitals: a 17-year time-series study

Objective

To describe the epidemiology of healthcare-associated Clostridioides difficile infection (HA-CDI) in two Québec hospitals in Canada following the 2003 epidemic and to evaluate the impact of antibiotic stewardship on the incidence of HA-CDI and the NAP1/027 strain.

Design

Time-series analysis.

Setting

Two Canadian tertiary care hospitals based in Montréal, Québec.

Patients

Patients with a positive assay for toxigenic C. difficile were identified through infection control surveillance. All cases of HA-CDI, defined as symptoms occurring after 72 hours of hospital admission or within 4 weeks of hospitalization, were included.

Methods

The incidence of HA-CDI and antibiotic utilization from 2003 to 2020 were analyzed with available C. difficile isolates. The impact of antibiotic utilization on HA-CDI incidence was estimated by a dynamic regression time-series model. Antibiotic utilization and the proportion of NAP1/027 strains were compared biannually for available isolates from 2010 to 2020.

Results

The incidence of HA-CDI decreased between 2003 and 2020 at both hospitals from 26.5 cases per 10,000 patient-days in 2003 to 4.9 cases per 10,000 patient-days in 2020 respectively. Over the study period, there were an increase in the utilization of third-generation cephalosporins and a decrease in usage of fluoroquinolones and clindamycin. A decrease in fluoroquinolone utilization was associated with a significant decrease in HA-CDI incidence as well as decrease in the NAP1/027 strain by approximately 80% in both hospitals.

Conclusions

Decreased utilization of fluoroquinolones in two Québec hospitals was associated with a decrease in the incidence of HA-CDI and a genotype shift from NAP1/027 to non-NAP1/027 strains.

Impact of the Introduction of a Two-Step Laboratory Diagnostic Algorithm in the Incidence and Earlier Diagnosis of Clostridioides difficile Infection

Our aim was to determine changes in the incidence of CD infection (CDI) following the introduction of a two-step diagnostic algorithm and to analyze CDI cases diagnosed in the study period. We retrospectively studied CDI (January 2009 to July 2018) in adults diagnosed by toxin enzyme immunoassay (EIA) (2009−2012) or toxin-EIA + polymerase chain reaction (PCR) algorithm (2013 onwards). A total of 443 patients with a first episode of CDI were included, 297 (67.1%) toxin-EIA-positive and 146 (32.9%) toxin-EIA-negative/PCR-positive were only identified through the two-step algorithm including the PCR test. The incidence of CDI increased from 0.9 to 4.7/10,000 patient-days (p < 0.01) and 146 (32.9%) toxin-negative CDI were diagnosed. Testing rate increased from 24.4 to 59.5/10,000 patient-days (p < 0.01) and the percentage of positive stools rose from 3.9% to 12.5% (p < 0.01). CD toxin-positive patients had a higher frequency of severe presentation and a lower rate of immunosuppressive drugs and inflammatory bowel disease. Mortality (16.3%) was significantly higher in patients with hematological neoplasm, intensive care unit admission and complicated disease. Recurrences (14.9%) were significantly higher with proton pump inhibitor exposure. The two-step diagnostic algorithm facilitates earlier diagnosis, potentially impacting patient outcomes and nosocomial spread. CD-toxin-positive patients had a more severe clinical presentation, probably due to increased CD bacterial load with higher toxin concentration. This early and easy marker should alert clinicians of potentially more severe outcomes.

Increased Community-Associated Clostridioides difficile Infections in Quebec, Canada, 2008-20151

The annual incidence rate of community-associated Clostridioides difficile infections in Quebec, Canada, has increased by 33.3%, from 0.51 (2008) to 0.68 (2015) cases/100,000 population, while incidence of healthcare-associated cases remained relatively stable. Possible causes include increased disease severity, increased antimicrobial drug use, emergence of virulent strains, and heightened physician awareness.

The Trend for Antibiotic Use for Clostridioides (Clostridium) difficile Infection in Japan

In Japan, there is no national surveillance study of Clostridioides (Clostridium) difficile infection (CDI), and details about the epidemiology and treatment status of CDI are unknown. Additionally, clinical practice guidelines (CPGs) for CDI are published by four different institutions. All CPGs recommend that the antimicrobials, vancomycin (VCM) and metronidazole (MNZ), should be selected according to disease severity. However, the trends for VCM and MNZ use in Japan remain unclear. Therefore, this study was aimed at clarifying the secular trends for VCM and MNZ use based on sales data from 2006 to 2015 and discussing its impact on CDI status and drug costs. This is the first study to clarify the antibiotic use trends for CDI treatment. We found that the total use increased over time (r = 0.0013, P_{for trend} < 0.0001). While VCM use significantly decreased (r = -0.0003, P_{for trend} = 0.0002), MNZ use increased (r = 0.0017, P_{for trend} < 0.0001). These results show that although treatment for CDI was in line with CPGs, CDI incidence might be on an increasing trend. Additionally, despite the increased total use, the total drug costs decreased by 55% ($ 25 million) from 2006 to 2015. It was also surmised that CDI treatment in compliance with CPGs would lead to a reduction in drug costs. Hence, to understand the epidemiology of CDI, it is important to continuously investigate the use of drugs used for CDI therapy.

The reference method influence on the sensitivity of the Clostridium difficile enzyme immunoassays: A meta analysis

The use of enzyme immunoassays to screen for toxins A and B produced by Clostridium difficile is a common procedure in algorithms designed for its detection. Moreover, the absence of a unique test capable of providing reliable results at low cost motivates a great discussion about which algorithm is the best. Thus, several studies have evaluated the performance of these enzyme immunoassays. However, all fail to provide sufficient explanations for the different behaviours observed in different studies that evaluate the same index test against a common reference method. Our main goal was to find out which factors affect the sensitivity of these assays, since the specificity is very close to 1. In this research, we verified that sensitivity increases with the prevalence rate and with the proportion of reported cases of onset diarrhea. Therefore, its use is advisable for high prevalence rates (e.g. in an epidemic setting). As far as reference methods are concerned, nucleic acid amplification tests can be used as a reference method, with a performance similar to the well-accepted toxigenic culture. The method chosen for toxigenicity screening in a toxigenic culture also seems to affect the evaluation performance of tests and should be better studied in the future.

Impact of a training program on the surveillance of Clostridioides difficile infection

A high degree of vigilance and appropriate diagnostic methods are required to detect Clostridioides difficile infection (CDI). We studied the effectiveness of a multimodal training program for improving CDI surveillance and prevention. Between 2011 and 2016, this program was made available to healthcare staff of acute care hospitals in Catalonia. The program included an online course, two face-to-face workshops and dissemination of recommendations on prevention and diagnosis. Adherence to the recommendations was evaluated through surveys administered to the infection control teams at the 38 participating hospitals. The incidence of CDI increased from 2.20 cases/10 000 patient-days in 2011 to 3.41 in 2016 (P &lt; 0.001). The number of hospitals that applied an optimal diagnostic algorithm rose from 32.0% to 71.1% (P = 0.002). Hospitals that applied an optimal diagnostic algorithm reported a higher overall incidence of CDI (3.62 vs. 1.92, P &lt; 0.001), and hospitals that were more active in searching for cases reported higher rates of hospital-acquired CDI (1.76 vs. 0.84, P &lt; 0.001). The results suggest that the application of a multimodal training strategy was associated with a significant rise in the reporting of CDI, as well as with an increase in the application of the optimal diagnostic algorithm.

Laboratory-developed test for detection of acute Clostridium difficile infections with the capacity for quantitative sample normalization

We describe a laboratory-developed test intended for the detection of acute Clostridium difficile infections (CDI) with the capacity for quantitative sample normalization. The test is based on the detection of the tcdB gene. However, this biomarker is also present among people without symptoms, implying that individuals with diarrhea, not caused by C. difficile may nonetheless test positive. Therefore, clinical diagnosis based on this format of testing can be challenging. In order to improve diagnostic assays capability, tcdB-based quantification methods were suggested as a potential solution, however they did not increase clinical specificity. We report methodology for a dual biomarker monitoring (total bacterial load and tcdB assay), allowing for the calculation of the relative presence of tcdB in the total bacterial population in the tested samples. We believe that this approach is clinically relevant to current assays and can improve CDI testing algorithms.

Clinical heterogeneity of patients with stool samples testing PCR+/Tox- from a two-step Clostridium difficile diagnostic algorithm

The clinical significance of indeterminate (PCR+/Tox-) results for patients tested with a two-step algorithm for Clostridium difficile infection (CDI) is uncertain. We aimed to evaluate the clinical presentation and 8-week outcomes of patients with indeterminate test results. Patients with stool samples testing positive by PCR and negative by toxin A/B immunoassay between February 1, 2017, and April 30, 2018, were assessed by antimicrobial stewardship program (ASP) clinicians and classified as colonized or infected. Retrospective chart review was performed to obtain outcomes occurring within 8 weeks of testing, including recurrent C. difficile diarrhea, subsequent treatment for CDI, follow-up C. difficile testing, all-cause mortality, and CDI-related complications. In total, 110 PCR+/Tox- patients were evaluated. ASP classified 54% of patients as infected and 46% as colonized. Patients assessed and classified as colonized did not have increased adverse outcomes by 8 weeks compared to those assessed as infected, despite not receiving treatment for CDI. We conclude that PCR+/Tox- patients are heterogeneous with respect to clinical presentation. Negative toxin A/B immunoassay in a two-step algorithm should not be interpreted in isolation to distinguish colonization from infection as many PCR+/Tox- results may be clinically significant for CDI.

Diagnostic Guidance for C. difficile Infections

Diagnosis of Clostridium difficile infection (CDI) can be challenging. First of all, there has been debate on which of the two reference assays, cell cytotoxicity neutralization assay (CCNA) or toxigenic culture (TC) should be considered the gold standard for CDI detection. Although the CCNA suffers most from suboptimal storage conditions and subsequent toxin degradation, TC is reported to falsely increase CDI detection rates as it cannot differentiate CDI patients from patients asymptomatically colonised by toxigenic C. difficile. Several rapid assays are available for CDI detection and fall into three broad categories: (1) enzyme immunoassays for glutamate dehydrogenase, (2) enzyme immunoassays for toxins A/B and (3) nucleic acid amplification tests detecting toxin genes. All three categories have their own limitations, being suboptimal specificity and/or sensitivity or the inability to discern colonised patients from CDI patients. In light of these limitations, multi-step algorithmic testing has now been advocated by international guidelines in order to optimize diagnostic accuracy. Despite these recommendations, testing methods between hospitals vary widely, which impacts CDI incidence rates. CDI incidence rates are also influenced by sample selection criteria, as several studies have shown that if not all unformed stool samples are tested for CDI, many cases may be missed due to an absence of clinical suspicion. Since methods for diagnosing CDI remain imperfect, there has been a growing interest in alternative testing strategies like faecal biomarkers, immune modulating interleukins, cytokines and imaging methods. At the moment, these alternative methods might play an adjunctive role, but they are not suitable to replace conventional CDI testing strategies.

Ten-year review of Clostridium difficile infection in acute care hospitals in the USA, 2005-2014

Clostridium difficile infection (CDI) is a major health concern for acute care hospitals because of the increase in the number and severity of cases. Using the Nationwide Inpatient Sample database, a 10-year review was performed on the trends in incidence, mortality, and hospital charges for CDI patients in acute care hospitals during 2005-2014. The review found increased CDI incidence and hospital charges, but decreased mortality during the 10-year study period.