Most clinical microbiology laboratories have replaced toxin immunoassay (EIA) alone with multistep testing (MST) protocols or nucleic acid amplification testing (NAAT) alone for the detection of C. difficile.

Study the effect of changing testing strategies on C. difficile detection and strain diversity.

Retrospective study.

A Veterans’ Affairs hospital.

Initially, toxin EIA testing was replaced by an MST approach utilizing a glutamate dehydrogenase (GDH) and toxin EIA followed by tcdB NAAT for discordant results. After 18 months, MST was replaced by a NAAT-only strategy. Available patient stool specimens were cultured for C. difficile. Restriction endonuclease analysis (REA) strain typing and quantitative in vitro toxin testing were performed on recovered isolates.

Before MST (toxin EIA), 79 of 708 specimens (11%) were positive, and after MST (MST-A), 121 of 517 specimens (23%) were positive (P < .0001). Prior to NAAT-only testing (MST-B), 80 of the 490 specimens (16%) were positive by MST, and after NAAT-only testing was implemented, 67 of the 368 specimens (18%) were positive (P = nonsignificant). After replacing toxin EIA testing, REA strain group diversity increased (8, 13, 13, and 10 REA groups in the toxin EIA, MST-A, MST-B, and NAAT-only periods, respectively) and in vitro toxin concentration decreased. The average log10 toxin concentration of the isolates were 2.08, 1.88, 1.20 and 1.55 ng/mL for the same periods, respectively.

MST and NAAT had similar detection rates for C. difficile. Compared to toxin testing alone, they detected increased diversity of C. difficile strains, many of which were low toxin producing.

To test the hypothesis that long-term care facility (LTCF) residents with Clostridium difficile infection (CDI) or asymptomatic carriage of toxigenic strains are an important source of transmission in the LTCF and in the hospital during acute-care admissions.

A 6-month cohort study with identification of transmission events was conducted based on tracking of patient movement combined with restriction endonuclease analysis (REA) and whole-genome sequencing (WGS).

Veterans Affairs hospital and affiliated LTCF.

The study included 29 LTCF residents identified as asymptomatic carriers of toxigenic C. difficile based on every other week perirectal screening and 37 healthcare facility-associated CDI cases (ie, diagnosis >3 days after admission or within 4 weeks of discharge to the community), including 26 hospital-associated and 11 LTCF-associated cases.

Of the 37 CDI cases, 7 (18·9%) were linked to LTCF residents with LTCF-associated CDI or asymptomatic carriage, including 3 of 26 hospital-associated CDI cases (11·5%) and 4 of 11 LTCF-associated cases (36·4%). Of the 7 transmissions linked to LTCF residents, 5 (71·4%) were linked to asymptomatic carriers versus 2 (28·6%) to CDI cases, and all involved transmission of epidemic BI/NAP1/027 strains. No incident hospital-associated CDI cases were linked to other hospital-associated CDI cases.

Our findings suggest that LTCF residents with asymptomatic carriage of C. difficile or CDI contribute to transmission both in the LTCF and in the affiliated hospital during acute-care admissions. Greater emphasis on infection control measures and antimicrobial stewardship in LTCFs is needed, and these efforts should focus on LTCF residents during hospital admissions.

To determine the impact of recurrent Clostridium difficile infection (RCDI) on patient behaviors following illness.

Using a computer algorithm, we searched the electronic medical records of 7 Chicago-area hospitals to identify patients with RCDI (2 episodes of CDI within 15 to 56 days of each other). RCDI was validated by medical record review. Patients were asked to complete a telephone survey. The survey included questions regarding general health, social isolation, symptom severity, emotional distress, and prevention behaviors.

In total, 119 patients completed the survey (32%). On average, respondents were 57.4 years old (standard deviation, 16.8); 57% were white, and ~50% reported hospitalization for CDI. At the time of their most recent illness, patients rated their diarrhea as high severity (58.5%) and their exhaustion as extreme (30.7%). Respondents indicated that they were very worried about getting sick again (41.5%) and about infecting others (31%). Almost 50% said that they have washed their hands more frequently (47%) and have increased their use of soap and water (45%) since their illness. Some of these patients (22%–32%) reported eating out less, avoiding certain medications and public areas, and increasing probiotic use. Most behavioral changes were unrelated to disease severity.

Having had RCDI appears to increase prevention-related behaviors in some patients. While some behaviors are appropriate (eg, handwashing), others are not supported by evidence of decreased risk and may negatively impact patient quality of life. Providers should discuss appropriate prevention behaviors with their patients and should clarify that other behaviors (eg, eating out less) will not affect their risk of future illness.

Infect Control Hosp Epidemiol. 2017;38:1351–1357

To report on the prevalence and incidence of Clostridium difficile infection (CDI) from 2009 to 2013 among Veterans Healthcare Administration patients

A retrospective descriptive analysis of data extracted from a large electronic medical record (EMR) database

Data were acquired from VHA healthcare records from 2009 to 2013 that included outpatient clinical visits, long-term care, and hospitalized care as well as pharmacy and laboratory information.

In 2009, there were 10,207 CDI episodes, and in 2013, there were 12,143 CDI episodes, an increase of 19.0%. The overall CDI rate increased by 8.4% from 193 episodes per 100,000 patient years in 2009 to 209 episodes per 100,000 patient years in 2013. Of the CDI episodes identified in 2009, 58% were identified during a hospitalization, and 42% were identified in an outpatient setting. In 2013, 44% of the CDI episodes were identified in an outpatient setting.

This is one of the largest studies that has utilized timely EMR data to describe the current CDI epidemiology at the VHA. Despite an aging population with greater burden of comorbidity than the general US population, our data show that VHA CDI rates stabilized between 2011 and 2013 following increases likely attributable to the introduction of the more sensitive nucleic acid amplification tests (NAATs). The findings in this report will help establish an accurate benchmark against which both current and future VA CDI prevention initiatives can be measured.

Infect. Control Hosp. Epidemiol. 2015;36(9):1038–1045

The molecular epidemiology of pediatric Clostridium difficile infection (CDI) is poorly understood. We aimed to identify the restriction endonuclease analysis (REA) groups causing CDI and to determine risk factors and outcomes associated with CDI caused by epidemic strains in children.

Retrospective cohort study

Inpatients and outpatients >1 year old receiving care between December 2012 and December 2013

An academic children’s hospital in Chicago, Illinois

C. difficile PCR-positive stools were cultured, and C. difficile isolates were typed by REA. REA of isolates from patients with multiple CDIs was performed to differentiate relapse (infection with same strain) from reinfection (different strains) irrespective of time between CDIs.

A total of 189 CDIs occurred among 145 patients. REA groups were widely distributed. The BI/NAP1/027 strain caused CDI in only 1 patient. DH/NAP11/106, the predominant epidemic strain identified, was associated with the use of third- or fourth-generation cephalosporins (risk ratio [RR], 3.2; 95% confidence interval [CI], 1.1–9.9; P=.04). CDI relapse commonly occurred up to 20 weeks later. Compared with CDI caused by non-DH/NAP11/106 strains, CDI caused by DH/NAP11/106 was more likely to result in multiple CDI relapses (40% vs 8%; P=.05) among children with multiple CDIs.

REA identified the exceedingly low prevalence of BI/NAP1/027 and the high prevalence of DH/NAP11/106, a common epidemic strain in the United Kingdom that is less often reported in the United States. CDI relapse commonly occurred up to 20 weeks from the previous CDI. Defining recurrent CDI as that occurring only within 8 weeks of the original infection may lead to misclassification of some recurrent CDIs as new CDIs in children.

Infect Control Hosp Epidemiol 2015;00(0): 1–7

To describe characteristics of Clostridium difficile infection (CDI) and markers of severe CDI among patients with hematologic malignancies.

Case-control study.

Tertiary care teaching hospital.

Inpatients with hematologic malignancies and CDI were age and time matched with 2 control inpatients without hematologic malignancies. Chart reviews were performed, and C. difficile isolates were strain typed.

Case patients (n = 41) and control patients (n = 82) patients were different in respect to receipt of immunosuppressive agents within 2 months (92.7% vs 25.6%; P < .0001); neutropenia within 2 months (75.6% vs 3.7%; P < .0001) and mean (± standard deviation) white blood cell (WBC) count at diagnosis (4.9 ± 14.1 vs 11.8 ± 6.8 × 103 cells/mL; P = .0002); baseline mean creatinine level (0.89 ± 0.1 vs 1.6 ± 2.4 mg/dL; P = .003), mean creatinine level at diagnosis (0.83 ± 0.4 vs 1.85 ± 1.9 mg/dL; P = .004), and creatinine increases of 1.5 times over baseline (2.4% vs 15.1%; P = .02). Immunosuppressive agents and creatinine level remained significant in multivariable analysis (P = .03 for both variables). Severity correlated with mortality when measured by alternate severity criteria but not when measured by the Society for Healthcare Epidemiology of America/Infectious Diseases Society of America criteria, which are based solely on WBC count and creatinine elevation. The prevalence of the epidemic BI/NAP1/027 strain was similar in both groups.

Patients with hematologic malignancies had lower creatinine levels at the time of CDI diagnosis compared with control patients. WBC counts also tended to be lower in case patients. CDI severity criteria based on WBC count and creatinine level may not be applicable to patients with hematologic malignancies.

Describe the clinical and molecular epidemiology of incident Clostridium difficile infection (CDI) cases in Chicago area acute healthcare facilities (HCFs).

Laboratory, clinical, and epidemiologic information was collected for patients with incident CDI who were admitted to acute HCFs in February 2009. Stool cultures and restriction endonuclease analysis typing of the recovered C. difficile isolates was performed.

Two hundred sixty-three patients from 25 acute HCFs.

Acute HCF rates ranged from 2 to 7 patients with CDI per 10,000 patient-days. The crude mortality rate was 8%, with 20 deaths occurring in patients with CDI. Forty-two (16%) patients had complications from CDI, including 4 patients who required partial, subtotal, or total colectomy, 3 of whom died. C. difficile was isolated and typed from 129 of 178 available stool specimens. The BI strain was identified in 79 (61%) isolates. Of patients discharged to long-term care who had their isolate typed, 36 (67%) had BI-associated CDI.

Severe disease was common and crude mortality was substantial among patients with CDI in Chicago area acute HCFs in February 2009. The outbreak-associated BI strain was the predominant endemic strain identified, accounting for nearly two-thirds of cases. Focal HCF outbreaks were not reported, despite the presence of the BI strain. Transfer of patients between acute and long-term HCFs may have contributed to the high incidence of BI cases in this investigation.