Clostridium difficile infection (CDI) is the most common infectious cause of nosocomial diarrhea, and its prevention is an urgent public health priority. However, reduction of CDI is challenging because of its complex pathogenesis, large reservoirs of colonized patients, and the persistence of infectious spores. The literature lacks high-quality evidence for evaluating interventions, and many hospitals have implemented bundled interventions to reduce CDI with variable results. Thus, we conducted a systematic review to examine the components of CDI bundles, their implementation processes, and their impact on CDI rates.

We conducted a comprehensive literature search of multiple computerized databases from their date of inception through April 30, 2016. The protocol was registered in PROSPERO, an international prospective register of systematic reviews. Bundle effectiveness, adherence, and study quality were assessed for each study meeting our criteria for inclusion.

In the 26 studies that met the inclusion criteria for this review, implementation and adherence factors to interventions were variably and incompletely reported, making study reproducibility and replicability challenging. Despite contextual differences and the variety of bundle components utilized, all 26 studies reported an improvement in CDI rates. However, given the lack of randomized controlled trials in the literature, assessing a causal relationship between bundled interventions and CDI rates is currently impossible.

Cluster randomized trials that include a rigorous assessment of the implementation of bundled interventions are urgently needed to causally test the effect of intervention bundles on CDI rates.

Infect Control Hosp Epidemiol 2017;38:639–650

Large-scale studies evaluating risk factors for Clostridium difficile infection (CDI), a leading cause of infectious diarrhea among patients undergoing stem cell transplantation (SCT), are lacking. We have evaluated risk factors for CDI among both autologous SCT (auto-SCT), and allogeneic SCT (allo-SCT) recipients using the National Inpatient Sample (NIS) database provided by the Healthcare Cost and Utilization Project (HCUP).

We used patient data obtained from the NIS database for all adult patients admitted for auto- and allo-SCTs from January 2001 to December 2010. We performed multivariate logistic regression analyses to evaluate risk factors of CDI in auto- and allo-SCT patients.

Auto-SCTs constituted 61.5% of all SCTs performed during the study period. Of the 53,072 auto-SCT patients, 5.8% had CDI, whereas 8.5% of 33,189 allo-SCT patients had CDI. Univariate analyses identified age, gender, indication for SCT, radiation as part of the conditioning regimen, respiratory failure, septicemia, lengthy hospital stay, and multiple comorbidities as risk factors for CDI in both subsets. On multivariate analyses for auto-SCT, there was significant correlation between age and the indication for transplant (P=.003), but the indication for either auto- or allo-SCT was not associated with CDI on multivariate analyses. The following factors were found to be associated with CDI: septicemia (auto-SCT odds ratio [OR],=1.64; 95% confidence interval [CI], 1.35–2; and allo-SCT OR, 1.69; 95% CI, 1.36–2.1), male gender (auto-SCT OR, 1.29; 95% CI, 1.09–1.53; and allo-SCT OR, 1.36; 95% CI, 1.18–1.57), lengthy hospital stay (auto-SCT OR, 2.81; 95% CI, 2.29–3.45; and allo-SCT OR, 2.63; 95% CI, 2.15–3.22), and presence of multiple comorbidities (auto-SCT OR, 1.32; 95% CI, 1.11–1.57; and allo-SCT OR, 1.18; 95% CI, 1.0–1.4).

The prevalence of CDI was higher among patients undergoing allo-SCT. CDI was significantly associated with longer hospital stay, septicemia, and male gender for auto- and allo-SCT recipients. While this analysis did not permit us to directly ascribe the associations to be causative for CDI, it identifies the more vulnerable population for CDI and provides a rationale for the development of more effective approaches to preventing CDI.

Infect Control Hosp Epidemiol 2017;38:651–657

To evaluate the use of a perianal swab to detect CDI.

A perianal swab was collected from each inpatient with a positive stool sample for C. difficile (by polymerase chain reaction [PCR] test) and was tested for C. difficile by PCR and by culture. The variables evaluated included demographics, CDI severity, bathing before perianal swab collection, hours between stool sample and perianal swab, cycle threshold (Ct) to PCR positivity, and doses of CDI treatment before stool sample and before perianal swab.

Of 83 perianal swabs, 59 (71.1%) tested positive for C. difficile by PCR when perianal swabs were collected an average of 21 hours after the stool sample. Compared with the respective stool sample, the perianal sample was less likely to grow C. difficile (P=.005) and had a higher PCR Ct (P<.001). A direct, significant but weak correlation was detected between the Ct for a positive perianal sample and the respective stool sample (r=0.36; P=.006). An inverse dose relationship was detected between PCR positivity and CDI treatment doses before perianal swab collection (P=.27).

Perianal swabs are a simple method to detect C. difficile tcdB gene by PCR, with a sensitivity of 71%. These data were limited because stool samples and perianal swabs were not collected simultaneously. Compared with stool samples, the perianal Ct values and culture results were consistent with a lower bacterial load on the perianal sample due to the receipt of more CDI treatment before collection or unknown factors affecting perianal skin colonization.

Infect Control Hosp Epidemiol 2017;38:658–662

Antibiotic resistance is a major threat to public health. Resistance is largely driven by antibiotic usage, which in many cases is unnecessary and can be improved. The impact of decreasing overall antibiotic usage on resistance is unknown and difficult to assess using standard study designs. The objective of this study was to explore the potential impact of reducing antibiotic usage on the transmission of multidrug-resistant organisms (MDROs).

We used agent-based modeling to simulate interactions between patients and healthcare workers (HCWs) using model inputs informed by the literature. We modeled the effect of antibiotic usage as (1) a microbiome effect, for which antibiotic usage decreases competing bacteria and increases the MDRO transmission probability between patients and HCWs and (2) a mutation effect that designates a proportion of patients who receive antibiotics to subsequently develop a MDRO via genetic mutation.

Intensive care unit

Absolute reduction in overall antibiotic usage by experimental values of 10% and 25%

Reducing antibiotic usage absolutely by 10% (from 75% to 65%) and 25% (from 75% to 50%) reduced acquisition rates of high-prevalence MDROs by 11.2% (P<.001) and 28.3% (P<.001), respectively. We observed similar effect sizes for low-prevalence MDROs.

In a critical care setting, where up to 50% of antibiotic courses may be inappropriate, even a moderate reduction in antibiotic usage can reduce MDRO transmission.

Infect Control Hosp Epidemiol 2017;38:663–669

To identify modifiable risk factors for acquisition of Klebsiella pneumoniae carbapenemase-producing Enterobacteriaceae (KPC) colonization among long-term acute-care hospital (LTACH) patients.

Multicenter, matched case-control study.

Four LTACHs in Chicago, Illinois.

Each case patient included in this study had a KPC-negative rectal surveillance culture on admission followed by a KPC-positive surveillance culture later in the hospital stay. Each matched control patient had a KPC-negative rectal surveillance culture on admission and no KPC isolated during the hospital stay.

From June 2012 to June 2013, 2,575 patients were admitted to 4 LTACHs; 217 of 2,144 KPC-negative patients (10.1%) acquired KPC. In total, 100 of these patients were selected at random and matched to 100 controls by LTACH facility, admission date, and censored length of stay. Acquisitions occurred a median of 16.5 days after admission. On multivariate analysis, we found that exposure to higher colonization pressure (OR, 1.02; 95% CI, 1.01–1.04; P=.002), exposure to a carbapenem (OR, 2.25; 95% CI, 1.06–4.77; P=.04), and higher Charlson comorbidity index (OR, 1.14; 95% CI, 1.01–1.29; P=.04) were independent risk factors for KPC acquisition; the odds of KPC acquisition increased by 2% for each 1% increase in colonization pressure.

Higher colonization pressure, exposure to carbapenems, and a higher Charlson comorbidity index independently increased the odds of KPC acquisition among LTACH patients. Reducing colonization pressure (through separation of KPC-positive patients from KPC-negative patients using strict cohorts or private rooms) and reducing carbapenem exposure may prevent KPC cross transmission in this high-risk patient population.

Infect Control Hosp Epidemiol 2017;38:670–677

The aim of this study was to quantify the correlation between adenosine triphosphate (ATP) measurements and bacterial cultures from duodenoscopes for evaluation of contamination following high-level disinfection.

Duodenoscopes used for any intended endoscopic retrograde cholangiopancreatography (ERCP) procedure were included. Microbiologic and ATP data were collected concomitantly and in the same manner from ERCP duodenoscopes.

A high-volume endoscopy unit at a tertiary referral acute-care facility.

Duodenoscopes were sampled for ATP and bacterial contamination in a contemporaneous and highly standardized fashion using a “flush-brush-flush” method for the working channel (WC) and a dry flocked swab for the elevator mechanism (EM). Specimens were processed for any aerobic bacterial growth (colony-forming units, CFU). Growth of CFU>0 and ATP relative light unit (RLU)>0 was considered a contaminated result. Frequency of discord between among WC and EM measurements were calculated using 2×2 contingency tables. The Spearman correlation coefficient was used to calculate the relatedness of bacterial contamination and ATP as continuous measurements.

The Spearman correlation coefficient did not demonstrate significant relatedness between ATP and CFU for either a WC or EM site. Among 390 duodenoscope sampling events, ATP and CFU assessments of contamination were discordant in 82 of 390 WC measurements (21%) and 331 of 390 of EM measurements (84.9%). The EM was frequently and markedly positive by ATP measurement.

ATP measurements correlate poorly with a microbiologic standard assessing duodenoscope contamination, particularly for EM sampling. ATP may reflect biological material other than nonviable aerobic bacteria and may not serve as an adequate marker of bacterial contamination.

Infect Control Hosp Epidemiol 2017;38:678–684

The National Healthcare Safety Network (NHSN) catheter-associated urinary tract infection (CAUTI) definition was revised as of January 2015 to exclude funguria and lower bacteriuria levels. We evaluated the effect of the CAUTI definition change on NHSN-defined central-line–associated bloodstream infection (CLABSI) outcomes.

We compared CAUTI and CLABSI NHSN-defined outcomes for calendar years 2014 and 2015 in the adult intensive care units (ICUs) of a single large health system. Changes in the event rates, the associated organisms, and the standardized infection ratio (SIR) were evaluated.

The study included 137 adult ICUs from 65 hospitals. The CAUTI SIR dropped from 1.04 in 2014 to 0.58 in 2015 (−44.2%), while the CLABSI SIR increased from 0.36 in 2014 to 0.47 in 2015 (+30.6%). CAUTI rates dropped 44.8% from 2.09 to 1.15 events per 1,000 device days (P<.001). Gram-positive–associated CAUTI rates dropped 36.7% from 0.34 to 0.22 per 1,000 device days (P=.007). CLABSI rates increased 27.1% from 0.71 to 0.90 per 1,000 device days (P=.027). Candida-associated CLABSI increased by 91.1% from 0.104 to 0.198 per 1,000 device days (P=.012), and Enterococcus-associated CLABSI increased by 121.6% from 0.071 to 0.16 per 1,000 device days (P=.008).

The revised CAUTI definition led to a large reduction in CAUTI rates and, in turn, an increase in candidemia and enterococcemia cases classified as CLABSI events. These findings have important implications on the perceived successes or failures to eliminate both infections.

Infect Control Hosp Epidemiol 2017;38:685–689

To assess the burden of bloodstream infections (BSIs) among pediatric hematology-oncology (PHO) inpatients, to propose a comprehensive, all-BSI tracking approach, and to discuss how such an approach helps better inform within-center and across-center differences in CLABSI rate

Prospective cohort study

US multicenter, quality-improvement, BSI prevention network

PHO centers across the United States who agreed to follow a standardized central-line–maintenance care bundle and track all BSI events and central-line days every month.

Infections were categorized as CLABSI (stratified by mucosal barrier injury–related, laboratory-confirmed BSI [MBI-LCBI] versus non–MBI-LCBI) and secondary BSI, using National Healthcare Safety Network (NHSN) definitions. Single positive blood cultures (SPBCs) with NHSN defined common commensals were also tracked.

Between 2013 and 2015, 34 PHO centers reported 1,110 BSIs. Among them, 708 (63.8%) were CLABSIs, 170 (15.3%) were secondary BSIs, and 232 (20.9%) were SPBCs. Most SPBCs (75%) occurred in patients with profound neutropenia; 22% of SPBCs were viridans group streptococci. Among the CLABSIs, 51% were MBI-LCBI. Excluding SPBCs, CLABSI rates were higher (88% vs 77%) and secondary BSI rates were lower (12% vs 23%) after the NHSN updated the definition of secondary BSI (P<.001). Preliminary analyses showed across-center differences in CLABSI versus secondary BSI and between SPBC and CLABSI versus non-CLABSI rates.

Tracking all BSIs, not just CLABSIs in PHO patients, is a patient-centered, clinically relevant approach that could help better assess across-center and within-center differences in infection rates, including CLABSI. This approach enables informed decision making by healthcare providers, payors, and the public.

Infect Control Hosp Epidemiol 2017;38:690–696

To report on the results of the Swiss national surgical site infection (SSI) surveillance program, including temporal trends, and to describe methodological characteristics that may influence SSI rates

Countrywide survey of SSI over a 4-year period. Analysis of prospectively collected data including patient and procedure characteristics as well as aggregated SSI rates stratified by risk categories, type of SSI, and time of diagnosis. Temporal trends were analyzed using stepwise multivariate logistic regression models with adjustment of the effect of the duration of participation in the surveillance program for confounding factors.

The study included 164 Swiss public and private hospitals with surgical activities.

From October 2011 to September 2015, a total of 187,501 operations performed in this setting were included. Cumulative SSI rates varied from 0.9% for knee arthroplasty to 14.4% for colon surgery. Postdischarge follow-up was completed in >90% of patients at 1 month for surgeries without an implant and in >80% of patients at 12 months for surgeries with an implant. High rates of SSIs were detected postdischarge, from 20.7% in colon surgeries to 93.3% in knee arthroplasties. Overall, the impact of the duration of surveillance was significantly and independently associated with a decrease in SSI rates in herniorraphies and C-sections but not for the other procedures. Nevertheless, some hospitals observed significant decreases in their rates for various procedures.

Intensive post-discharge surveillance may explain high SSI rates and cause artificial differences between programs. Surveillance per se, without structured and mandatory quality improvement efforts, may not produce the expected decrease in SSI rates.

Infect Control Hosp Epidemiol 2017;38:697–704

Heater-cooler units (HCUs) have been shown to be a source of Mycobacterium chimaera infections. For the past year, weekly water samples have been taken from HCUs used at University Hospitals Birmingham (UHB) NHS Foundation Trust. We report the microbial contamination of the HCUs over a year detailing the decontamination regimes applied at UHB to reduce the microbial load.

Observational study

UHB is a tertiary referral teaching hospital in Birmingham, United Kingdom, that provides clinical services to nearly 1 million patients every year. The UHB Cardiac department is one of the largest in the United Kingdom and provides treatment for adult patients with a wide range of cardiac diseases.

Water samples taken from HCUs used at UHB for cardiopulmonary bypass surgery were sampled over a year to determine the number of microorganisms by membrane filtration. Various decontamination processes were employed throughout the year.

Varying total viable counts containing a wide variety of microorganisms were obtained from water inside the HCUs. No M. chimaera were isolated after replacement of the HCU internal tubing. Stringent decontamination regimes resulted in degradation of the HCUs and increased TVCs after several months.

More work is required to ensure effective decontamination processes to reduce the microbial load within the HCUs. Our studies indicate that weekly water sampling for TVC will be required indefinitely to monitor the water quality in these units as well as regular replacement of the tubing to control the build-up of biofilm.

Infect Control Hosp Epidemiol 2017;38:705–711

To explore the impact of environmental design on doffing personal protective equipment in a simulated healthcare environment.

A mixed-methods approach was used that included human-factors usability testing and qualitative questionnaire responses. A patient room and connecting anteroom were constructed for testing purposes. This experimental doffing area was designed to overcome the environmental failures identified in a previous study and was not constructed based on any generalizable hospital standard.

In total, 72 healthcare workers from Ontario, Canada, took part in the study and tested the simulated doffing area. The following environmental design changes were tested and were deemed effective: increasing prominence of color-coded zones; securing disinfectant wipes and hand sanitizer; outlining disposal bins locations; providing mirrors to detect possible contamination; providing hand rails to assist with doffing; and restricting the space to doff. Further experimentation and iterative design are required with regard to several important features: positioning the disposal bins for safety, decreasing the risk of contamination and user accessibility; optimal positioning of mirrors for safety; communication within the team; and positioning the secondary team member for optimal awareness. Additional design suggestions also emerged during this study, and they require future investigation.

This study highlights the importance of the environment on doffing personal protective equipment in a healthcare setting. Iterative testing and modification of the design of the environment (doffing area) are important to enhancing healthcare worker safety.

Infect Control Hosp Epidemiol 2017;38:712–717