To investigate an outbreak of Pseudomonas aeruginosa infections and colonization in a neonatal intensive care unit.

Infection control assessment, environmental evaluation, and case-control study.

Newly built community-based hospital, 28-bed neonatal intensive care unit.

Neonatal intensive care unit patients receiving care between June 1, 2013, and September 30, 2014.

Case finding was performed through microbiology record review. Infection control observations, interviews, and environmental assessment were performed. A matched case-control study was conducted to identify risk factors for P. aeruginosa infection. Patient and environmental isolates were collected for pulsed-field gel electrophoresis to determine strain relatedness.

In total, 31 cases were identified. Case clusters were temporally associated with absence of point-of-use filters on faucets in patient rooms. After adjusting for gestational age, case patients were more likely to have been in a room without a point-of-use filter (odds ratio [OR], 37.55; 95% confidence interval [CI], 7.16–∞). Case patients had higher odds of exposure to peripherally inserted central catheters (OR, 7.20; 95% CI, 1.75–37.30) and invasive ventilation (OR, 5.79; 95% CI, 1.39–30.62). Of 42 environmental samples, 28 (67%) grew P. aeruginosa. Isolates from the 2 most recent case patients were indistinguishable by pulsed-field gel electrophoresis from water-related samples obtained from these case-patient rooms.

This outbreak was attributed to contaminated water. Interruption of the outbreak with point-of-use filters provided a short-term solution; however, eradication of P. aeruginosa in water and fixtures was necessary to protect patients. This outbreak highlights the importance of understanding the risks of stagnant water in healthcare facilities.

Infect Control Hosp Epidemiol 2017;38:801–808

To characterize the risk of infection after MRSA decolonization with intranasal mupirocin.

Multicenter, retrospective cohort study.

Tertiary care neonatal intensive care units (NICUs) from 3 urban hospitals in the United States ranging in size from 45 to 100 beds.

MRSA-colonized neonates were identified from NICU admissions occurring from January 2007 to December 2014, during which a targeted decolonization strategy was used for MRSA control. In 2 time-to-event analyses, MRSA-colonized neonates were observed from the date of the first MRSA-positive surveillance screen until (1) the first occurrence of novel gram-positive cocci in sterile culture or discharge or (2) the first occurrence of novel gram-negative bacilli in sterile culture or discharge. Mupirocin exposure was treated as time varying.

A total of 522 MRSA-colonized neonates were identified from 16,144 neonates admitted to site NICUs. Of the MRSA-colonized neonates, 384 (74%) received mupirocin. Average time from positive culture to mupirocin treatment was 3.5 days (standard deviation, 7.2 days). The adjusted hazard of gram-positive cocci infection was 64% lower among mupirocin-exposed versus mupirocin-unexposed neonates (hazard ratio, 0.36; 95% confidence interval [CI], 0.17–0.76), whereas the adjusted hazard ratio of gram-negative bacilli infection comparing mupirocin-exposed and -unexposed neonates was 1.05 (95% CI, 0.42–2.62).

In this multicentered cohort of MRSA-colonized neonates, mupirocin-based decolonization treatment appeared to decrease the risk of infection with select gram-positive organisms as intended, and the treatment was not significantly associated with risk of subsequent infections with organisms not covered by mupirocin’s spectrum of activity.

Infect Control Hosp Epidemiol 2017;38:930–936

Effective perioperative hand antisepsis is crucial for the safety of patients and medical staff in surgical rooms. The antimicrobial effectiveness of different antiseptic methods, including conventional hand scrubs and waterless hand rubs, has not been well evaluated.

A randomized controlled trial was conducted to investigate the effectiveness of the 3 antiseptic methods among surgical staff of Taipei Medical University—Shuang Ho Hospital. For each method used, a group of 80 participants was enrolled.

Surgical hand cleansing with conventional 10% povidone–iodine scrub, conventional 4% chlorhexidine scrub, or waterless hand rub (1% chlorhexidine gluconate and 61% ethyl alcohol).

Colony-forming unit (CFU) counts were collected using the hand imprinting method before and after disinfection and after surgery. After surgical hand disinfection, the mean CFU counts of the conventional chlorhexidine (0.5±0.2, P<0.01) and waterless hand rub groups (1.4±0.7, P<0.05) were significantly lower than that of the conventional povidone group (4.3±1.3). No significant difference was observed in the mean CFU count among the groups after surgery. Similar results were obtained when preexisting differences before disinfection were considered in the analysis of covariance. Furthermore, multivariate regression indicated that the antiseptic method (P=.0036), but not other variables, predicted the mean CFU count.

Conventional chlorhexidine scrub and waterless hand rub were superior to a conventional povidone–iodine product in bacterial inhibition. We recommend using conventional chlorhexidine scrub as a standard method for perioperative hand antisepsis. Waterless hand rub may be used if the higher cost is affordable.

Infect Control Hosp Epidemiol 2017;38:417–422

To assess the structure and quality of surveillance activities and to validate outcome detection in the Swiss national surgical site infection (SSI) surveillance program.

Countrywide survey of SSI surveillance quality.

147 hospitals or hospital units with surgical activities in Switzerland.

Site visits were conducted with on-site structured interviews and review of a random sample of 15 patient records per hospital: 10 from the entire data set and 5 from a subset of patients with originally reported infection. Process and structure were rated in 9 domains with a weighted overall validation score, and sensitivity, specificity, positive predictive value, and negative predictive value were calculated for the identification of SSI.

Of 50 possible points, the median validation score was 35.5 (range, 16.25–48.5). Public hospitals (P<.001), hospitals in the Italian-speaking region of Switzerland (P=.021), and hospitals with longer participation in the surveillance (P=.018) had higher scores than others. Domains that contributed most to lower scores were quality of chart review and quality of data extraction. Of 49 infections, 15 (30.6%) had been overlooked in a random sample of 1,110 patient records, accounting for a sensitivity of 69.4% (95% confidence interval [CI], 54.6%–81.7%), a specificity of 99.9% (95% CI, 99.5%–100%), a positive predictive value of 97.1% (95% CI, 85.1%–99.9%), and a negative predictive value of 98.6% (95% CI, 97.7%–99.2%).

Irrespective of a well-defined surveillance methodology, there is a wide variation of SSI surveillance quality. The quality of chart review and the accuracy of data collection are the main areas for improvement.

Infect Control Hosp Epidemiol 2017;38:1172–1181

To evaluate the impact of multidrug-resistant gram-negative rod (MDR-GNR) infections on mortality and healthcare resource utilization in community hospitals.

Two matched case-control analyses.

Six community hospitals participating in the Duke Infection Control Outreach Network from January 1, 2010, through December 31, 2012.

Adult patients admitted to study hospitals during the study period.

Patients with MDR-GNR bloodstream and urinary tract infections were compared with 2 groups: (1) patients with infections due to nonMDR-GNR and (2) control patients representative of the nonpsychiatric, non-obstetric hospitalized population. Four outcomes were assessed: mortality, direct cost of hospitalization, length of stay, and 30-day readmission rates. Multivariable regression models were created to estimate the effect of MDR status on each outcome measure.

No mortality difference was seen in either analysis. Patients with MDR-GNR infections had 2.03 higher odds of 30-day readmission compared with patients with nonMDR-GNR infections (95% CI, 1.04–3.97, P=.04). There was no difference in hospital direct costs between patients with MDR-GNR infections and patients with nonMDR-GNR infections. Hospitalizations for patients with MDR-GNR infections cost $5,320.03 more (95% CI, $2,366.02–$8,274.05, P<.001) and resulted in 3.40 extra hospital days (95% CI, 1.41–5.40, P<.001) than hospitalizations for control patients.

Our study provides novel data regarding the clinical and financial impact of MDR gram-negative bacterial infections in community hospitals. There was no difference in mortality between patients with MDR-GNR infections and patients with nonMDR-GNR infections or control patients.

Infect Control Hosp Epidemiol 2016;1–8

The VU University Medical Center, a tertiary-care hospital in the Netherlands, has adopted a dress code based on national guidelines. It includes uniforms provided by the hospital and a ‘bare-below-the-elbow’ policy for all healthcare workers (HCWs) in direct patient care. Because compliance was poor, we sought to improve adherence by interventions targeted at the main causes of noncompliance.

To measure compliance with the dress code, to assess causes of noncompliance and to assess whether a behavioral approach (combing a nominal group technique with participatory action) is effective in improving compliance

Between March 2014 and June 2016, a total of 1,920 HCWs were observed in hospital hallways for adherence to the policy, at baseline, and at follow-up measurements. Based on the outcome of the baseline measurement, a nominal group technique was applied to assess causes of noncompliance. The causes revealed served as input for interventions that were developed, prioritized, and tailored to specific groups of HCWs and specific departments through participatory action.

We identified lack of knowledge, lack of facilities, and negative attitudes as the main causes of noncompliance. The importance of each cause varied for different groups of HCWs. Tailored interventions targeted at these causes increased overall compliance by 39.6% (95% CI, 31.7–47.5).

The combination of a nominal group technique and participatory action approach is an effective method to increase and sustain compliance with hospital dress code. This combined approach may also be useful to improve adherence to other guidelines.

Infect Control Hosp Epidemiol 2017;38:1435–1440

To describe the characteristics and impact of Clostridium difficile infection (CDI) in a long-term acute-care hospital (LTACH).

Retrospective matched cohort study.

A 38-bed, urban, university-affiliated LTACH.

The characteristics of LTACH-onset CDI were assessed among patients hospitalized between July 2008 and October 2015. Patients with CDI were matched to concurrently hospitalized patients without a diagnosis of CDI. Severe CDI was defined as CDI with 2 or more of the following criteria: age ≥65 years, serum creatinine ≥2 mg/dL, or peripheral leukocyte count ≥20,000 cells/μL. A conditional Poisson regression model was developed to determine characteristics associated with a composite primary outcome of 30-day readmission to an acute-care hospital, or mortality.

The overall incidence of CDI was 21.4 cases per 10,000 patient days, with 27% of infections classified as severe. Patients with CDI had a mean age of 70 years (SD, 14 years), a mean Charlson comorbidity index of 3.6 (SD, 2.0), a median length of stay of 33 days (interquartile range [IQR], 24–45 days), and a median time between admission and CDI diagnosis of 16 days (IQR, 9–23 days). The most commonly prescribed antibiotic preceding a CDI diagnosis was a cephalosporin, with median duration of 8 days (IQR, 4–14 days). In multivariate analysis, CDI was not significantly associated with the primary outcome (relative risk, 0.97; 95% CI, 0.59–1.58).

Incidence of CDI in an urban, university-affiliated LTACH was high. Future research should focus on infection prevention measures to decrease the burden of CDI in this complex patient population.

Infect Control Hosp Epidemiol 2017;38:294–299

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

Infants and young children are frequently colonized with C. difficile but rarely have symptomatic disease. However, C. difficile testing remains prevalent in this age group.

To design a computerized provider order entry (CPOE) alert to decrease testing for C. difficile in young children and infants.

An interventional age-targeted before-after trial with comparison group

Monroe Carell Jr. Children’s Hospital at Vanderbilt University, Nashville, Tennessee.

All children seen in the inpatient or emergency room settings from July 2012 through July 2013 (pre-CPOE alert) and September 2013 through September 2014 (post-CPOE alert)

In August of 2013, we implemented a CPOE alert advising against testing in infants and young children based on the American Academy of Pediatrics recommendations with an optional override. We further offered healthcare providers educational seminars regarding recommended C. difficile testing.

The average monthly testing rate significantly decreased after the CPOE alert for children 0–11 months old (11.5 pre-alert vs 0 post-alert per 10,000 patient days; P<.001) and 12–35 months old (61.6 pre-alert vs 30.1 post-alert per 10,000 patients days; P<.001), but not for those children ≥36 months old (50.9 pre-alert vs 46.4 post-alert per 10,000 patient days; P=.3) who were not targeted with a CPOE alert. There were no complications in those children who testing positive for C. difficile.

The average monthly testing rate for C. difficile for children <35 months old decreased without complication after the use of a CPOE alert in those who tested positive for C. difficile.

Infect Control Hosp Epidemiol 2017;38:542–546

We describe the use of implementation science at the unit level and organizational level to guide an intervention to reduce central-line–associated bloodstream infections (CLABSIs) in a high-volume, regional, burn intensive care unit (BICU).

A single center observational quasi-experimental study.

A regional BICU in Maryland serving 300–400 burn patients annually.

In 2011, an organizational-level and unit-level intervention was implemented to reduce the rates of CLABSI in a high-risk patient population in the BICU. At the organization level, leaders declared a goal of zero infections, created an infrastructure to support improvement efforts by creating a coordinating team, and engaged bedside staff. Performance data were transparently shared. At the unit level, the Comprehensive Unit-based Safety Program (CUSP)/ Translating Research Into Practice (TRIP) model was used. A series of interventions were implemented: development of new blood culture procurement criteria, implementation of chlorhexidine bathing and chlorhexidine dressings, use of alcohol impregnated caps, routine performance of root-cause analysis with executive engagement, and routine central venous catheter changes.

The use of an implementation science framework to guide multiple interventions resulted in the reduction of CLABSI rates from 15.5 per 1,000 central-line days to zero with a sustained rate of zero CLABSIs over 3 years (rate difference, 15.5; 95% confidence interval, 8.54–22.48).

CLABSIs in high-risk units may be preventable with the a use a structured organizational and unit-level paradigm.

Infect Control Hosp Epidemiol 2017;38:1306–1311

To assess whether differences in surveillance methods or underlying populations significantly influence internationally reported national SSI rates by comparing surveillance data from 2 countries.

Retrospective cohort.

England and Norway.

We assessed the population under surveillance and surveillance methodology to compare SSI rates in 2 countries (September 2012–January 2015) for 4 surgical categories: coronary artery bypass graft (CABG), colon surgery, cholecystectomy, and hip prosthesis (HPRO). We compared the inpatient SSI incidence using logistic regression, adjusting for the following known risk factors: sex, age, ASA score, wound class, postoperative hospital days, and operation duration. Subsequently, we restricted further analyses to the procedures reported by both countries.

There were important differences in case definitions for superficial infection, so we restricted our analyses to deep incisional and organ-space SSIs. For CABG, the crude odds ratio (OR) for England compared to Norway was 2.4 (95% CI, 1.4–4.4), whereas adjusted OR (aOR) lost significance (aOR, 1.1; 95% CI, 0.57–2.0). For colon surgery the decreased odds (OR, 0.68; 95% CI, 0.56–0.81) remained significant after adjustment (aOR, 0.42; 95% CI, 0.34–0.51). We found no associations for cholecystectomy. For HPRO, the crude OR suggested no significant difference (OR, 1.2; 95% CI, 0.72–2.1), whereas the aOR was significantly lower in England (aOR, 0.45; 95% CI, 0.25–0.81). Including only the subset of procedures reported by both countries yielded comparable results.

Differences in case definitions and population under surveillance in the English and Norwegian SSI surveillance systems affected SSI estimates, making the comparison of crude rates unreliable. Standardized definitions and adjustment for established risk factors are essential for European comparisons to guide related public health actions.

Infect Control Hosp Epidemiol 2017;38:162–171

To evaluate interventions to reduce avoidable antibiotic use on pediatric oncology and hematopoietic stem cell transplantation (HSCT) services.

Interrupted time series.

Academic pediatric hospital with separate oncology and HSCT services.

Children admitted to the services during baseline (October 2011–August 2013) and 2 intervention periods, September 2013–June 2015 and July 2015–June 2016, including 1,525 oncology hospitalizations and 301 HSCT hospitalizations.

In phase 1, we completed an update of the institutional febrile neutropenia (FN) guideline for the pediatric oncology service, recommending first-line β-lactam monotherapy rather than routine use of 2 gram-negative agents. Phase 2 included updating the HSCT service FN guideline and engagement with a new pediatric antimicrobial stewardship program. The use of target antibiotics (tobramycin and ciprofloxacin) was measured in days of therapy per 1,000 patient days collected from administrative data. Intervention effects were evaluated using interrupted time series with segmented regression.

Phase 1 had mixed effects–long-term reduction in tobramycin use (97% below projected at 18 months) but rebound with increasing slope in ciprofloxacin use (+18% per month). Following phase 2, tobramycin and ciprofloxacin use on the oncology service were both 99% below projected levels at 12 months. On the HSCT service, tobramycin use was 99% below the projected level and ciprofloxacin use was 96% below the projected level at 12 months.

Locally adapted guidelines can facilitate practice changes in oncology and HSCT settings. More comprehensive and ongoing interventions, including follow-up education, feedback, and engagement of companion services may be needed to sustain changes.

Infect Control Hosp Epidemiol 2017;38:1039–1047

To evaluate the efficacy of a multijet cold-plasma system and its efficacy in decontaminating 2 surfaces commonly found in hospitals

An in vitro study of common causes of healthcare-acquired infection

Log10 9 cultures of methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, extended spectrum β-lactamase–producing Escherichia coli, and Acinetobacter baumannii were applied to 5-cm2 sections of stainless steel and mattress. Human serum albumin (HSA) was used as a proxy marker for organic material, and atomic force microscopy (AFM) was used to study the impact on bacterial cell structure. The inoculated surfaces were exposed to a cold-air-plasma–generating multijet prototype for 15, 20, 30, and 45 seconds.

After 45 seconds, at least 3 to 4 log reductions were achieved for all bacteria on the mattress, while 3 to 6 log reductions were observed on stainless steel. The presence of HSA had no appreciable effect on bacterial eradication. The surfaces with bacteria exposed to AFM showed significant morphological changes indicative of “etching” due to the action of highly charged ions produced by the plasma.

This multijet cold-plasma prototype has the potential to augment current environmental decontamination approaches but needs further evaluation in a clinical setting to confirm its effectiveness.

Infect Control Hosp Epidemiol 2017;38:1182–1187

To evaluate the impact of no-touch terminal room no-touch disinfection using ultraviolet wavelength C germicidal irradiation (UVGI) on C. difficile infection (CDI) rates on inpatient units with persistently high rates of CDI despite infection control measures.

Interrupted time-series analysis with a comparison arm.

3 adult hematology-oncology units in a large, tertiary-care hospital.

We conducted a 12-month prospective valuation of UVGI. Rooms of patients with CDI or on contact precautions were targeted for UVGI upon discharge using an electronic patient flow system. Incidence rates of healthcare-onset CDI were compared for the baseline period (January 2013–December 2013) and intervention period (February 2014–January 2015) on study units and non–study units using a mixed-effects Poisson regression model with random effects for unit and time in months.

During a 52-week intervention period, UVGI was deployed for 542 of 2,569 of all patient discharges (21.1%) on the 3 study units. The CDI rate declined 25% on study units and increased 16% on non-study units during the intervention compared to the baseline period. We detected a significant association between UVGI and decrease in CDI incidence (incidence rate ratio [IRR], 0.49; 95% confidence interval [CI], 0.26–0.94; P=.03) on the study units but not on the non-study units. The impact of UVGI use on average room-cleaning time and turnaround time was negligible compared to the baseline period.

Targeted deployment of UVGI to rooms of high-risk patients at discharge resulted in a substantial reduction of CDI incidence without adversely impacting room turnaround.

Infect Control Hosp Epidemiol 2016;1–6

To compare interrater reliabilities for ventilator-associated event (VAE) surveillance, traditional ventilator-associated pneumonia (VAP) surveillance, and clinical diagnosis of VAP by intensivists.

A retrospective study nested within a prospective multicenter quality improvement study.

Intensive care units (ICUs) within 5 hospitals of the Centers for Disease Control and Prevention Epicenters.

Patients who underwent mechanical ventilation.

We selected 150 charts for review, including all VAEs and traditionally defined VAPs identified during the primary study and randomly selected charts of patients without VAEs or VAPs. Each chart was independently reviewed by 2 research assistants (RAs) for VAEs, 2 hospital infection preventionists (IPs) for traditionally defined VAP, and 2 intensivists for any episodes of pulmonary deterioration. We calculated interrater agreement using κ estimates.

The 150 selected episodes spanned 2,500 ventilator days. In total, 93–96 VAEs were identified by RAs; 31–49 VAPs were identified by IPs, and 29–35 VAPs were diagnosed by intensivists. Interrater reliability between RAs for VAEs was high (κ, 0.71; 95% CI, 0.59–0.81). Agreement between IPs using traditional VAP criteria was slight (κ, 0.12; 95% CI, −0.05–0.29). Agreement between intensivists was slight regarding episodes of pulmonary deterioration (κ 0.22; 95% CI, 0.05–0.39) and was fair regarding whether episodes of deterioration were attributable to clinically defined VAP (κ, 0.34; 95% CI, 0.17–0.51). The clinical correlation between VAE surveillance and intensivists’ clinical assessments was poor.

Prospective surveillance using VAE criteria is more reliable than traditional VAP surveillance and clinical VAP diagnosis; the correlation between VAEs and clinically recognized pulmonary deterioration is poor.

Infect Control Hosp Epidemiol 2017;38:172–178

To investigate whether comparison by deep or adjusted deep surgical site infection (SSI) rates in orthopedic surgeries are a better basis for feedback to Finnish hospitals than overall SSI rates

Retrospective cohort study

Hospitals conducting surveillance of hip arthroplasties (HPROs) and knee arthroplasties (KPROs) in the Finnish Hospital Infection Program

We analyzed surveillance data for 73,227 HPROs and 56,860 KPROs performed in 18 hospitals during 1999–2014. For each hospital, the overall, deep, and adjusted deep SSI rates with 95% confidence intervals (CIs) were calculated, and the hospital ranks were simulated in the Bayesian framework. Adjustments were performed using relevant patient and hospital characteristics. The correlation between the median expected hospital ranks in overall versus deep SSI rates and deep vs adjusted deep SSI rates were assessed using Spearman’s correlation coefficient ρ.

For HPRO, the overall SSI rates ranged from 0.92 to 6.83, the deep SSI rates ranged from 0.34 to 1.86, and the adjusted deep hospital-specific SSI rates ranged from 0.37 to 1.85. For KPRO, the overall SSI rates ranged from 0.71 to 5.03, the deep SSI rates ranged from 0.42 to 1.60, and the adjusted deep hospital-specific SSI rates ranged from 0.56 to 1.55. For both procedures, the 95% CIs of the rates between hospitals largely overlapped; only single outliers were detected. Hospital rank did not correlate between overall and deep SSI rates (HPRO, ρ=0.03; KPRO, ρ=0.40), but a correlation was observed in hospital rank for deep and adjusted deep SSI rates (HPRO, ρ=0.85; KPRO, ρ=0.94).

Deep SSI rates may be a better tool for interhospital comparisons than overall SSI rates. Although the adjustment could lead to fairer hospital ranking, it is not always necessary for feedback.

Infect Control Hosp Epidemiol 2017;38:423–429

Survey results suggest that prolonged administration of prophylactic antibiotics is common after mastectomy with reconstruction. We determined utilization, predictors, and outcomes of postdischarge prophylactic antibiotics after mastectomy with or without immediate breast reconstruction.

Retrospective cohort.

Commercially insured women aged 18–64 years coded for mastectomy from January 2004 to December 2011 were included in the study. Women with a preexisting wound complication or septicemia were excluded.

Predictors of prophylactic antibiotics within 5 days after discharge were identified in women with 1 year of prior insurance enrollment; relative risks (RR) were calculated using generalized estimating equations.

Overall, 12,501 mastectomy procedures were identified; immediate reconstruction was performed in 7,912 of these procedures (63.3%). Postdischarge prophylactic antibiotics were used in 4,439 procedures (56.1%) with immediate reconstruction and 1,053 procedures (22.9%) without immediate reconstruction (P<.001). The antibiotics most commonly prescribed were cephalosporins (75.1%) and fluoroquinolones (11.1%). Independent predictors of postdischarge antibiotics were implant reconstruction (RR, 2.41; 95% confidence interval [CI], 2.23–2.60), autologous reconstruction (RR, 2.17; 95% CI, 1.93–2.45), autologous reconstruction plus implant (RR, 2.11; 95% CI, 1.92–2.31), hypertension (RR, 1.05; 95% CI, 1.00–1.10), tobacco use (RR, 1.07; 95% CI, 1.01–1.14), surgery at an academic hospital (RR, 1.14; 95% CI, 1.07–1.21), and receipt of home health care (RR, 1.11; 95% CI, 1.04–1.18). Postdischarge prophylactic antibiotics were not associated with SSI after mastectomy with or without immediate reconstruction (both P>.05).

Prophylactic postdischarge antibiotics are commonly prescribed after mastectomy; immediate reconstruction is the strongest predictor. Stewardship efforts in this population to limit continuation of prophylactic antibiotics after discharge are needed to limit antimicrobial resistance.

Infect Control Hosp Epidemiol 2017;38:1048–1054

To determine whether the seasonality of surgical site infections (SSIs) can be explained by changes in temperature.

Retrospective cohort analysis.

The National Inpatient Sample database.

All hospital discharges with a primary diagnosis of SSI from 1998 to 2011 were considered cases. Discharges with a primary or secondary diagnoses of specific surgeries commonly associated with SSIs from the previous and current month served as our “at risk” cohort.

We modeled the national monthly count of SSI cases both nationally and stratified by region, sex, age, and type of institution. We used data from the National Climatic Data Center to estimate the monthly average temperatures for all hospital locations. We modeled the odds of having a primary diagnosis of SSI as a function of demographics, payer, location, patient severity, admission month, year, and the average temperature in the month of admission.

SSI incidence is highly seasonal, with the highest SSI incidence in August and the lowest in January. During the study period, there were 26.5% more cases in August than in January (95% CI, 23.3–29.7). Controlling for demographic and hospital-level characteristics, the odds of a primary SSI admission increased by roughly 2.1% per 2.8°C (5°F) increase in the average monthly temperature. Specifically, the highest temperature group, >32.2°C (>90°F), was associated with an increase in the odds of an SSI admission of 28.9% (95% CI, 20.2–38.3) compared to temperatures <4.4°C (<40°F).

At population level, SSI risk is highly seasonal and is associated with warmer weather.

Infect Control Hosp Epidemiol 2017;38:809–816

We investigated an increase in the incidence of healthcare-associated Clostridium difficile infection (CDI) that occurred following a change from a bleach disinfectant to a peracetic acid–based disinfectant.

To evaluate the efficacy of the peracetic acid–based disinfectant.

Laboratory-based product evaluation.

The commercial peracetic acid–based product is activated on site by mixing a small volume of concentrated hydrogen peroxide and peracetic acid present in a “SmartCap” reservoir with the remaining contents of the container. We measured concentrations of peracetic acid in newly activated and in-use product and determined the stability of nonactivated and activated product. We tested the efficacy of the product against C. difficile spores using the American Society for Testing and Materials standard quantitative carrier disk test method.

Measured concentrations of peracetic acid (50–800 parts per million [ppm]) were significantly lower than the level stated on the product label (1,500 ppm), and similar results were obtained for containers from multiple lot numbers and from another hospital. Product with peracetic acid levels below 600 ppm had significantly reduced activity against C. difficile spores. Peracetic acid concentrations were reduced markedly after storage of either activated or nonactivated product for several weeks. The Environmental Protection Agency confirmed the finding of low disinfectant levels and ordered discontinuation of sale of the product.

Use of a defective peracetic acid–based surface disinfectant may have contributed to an increase in healthcare-associated CDI. Our findings highlight the importance of evaluating the efficacy of liquid disinfectants in healthcare settings.

Infect Control Hosp Epidemiol 2017;38:300–305

To characterize the microbial disruption indices of hospitalized patients to predict colonization with multidrug-resistant organisms (MDROs).

A cross-sectional survey of the fecal microbiome was conducted in a tertiary referral, acute-care hospital in Boston, Massachusetts.

The study population consisted of adult patients hospitalized in general medical/surgical wards.

Rectal swabs were obtained from patients within 48 hours of hospital admission and screened for MDRO colonization using conventional culture techniques. The V4 region of the 16S rRNA gene was sequenced to assess the fecal microbiome. Microbial diversity and composition, as well as the functional potential of the microbial communities present in fecal samples, were compared between patients with and without MDRO colonization.

A total of 44 patients were included in the study, of whom 11 (25%) were colonized with at least 1 MDRO. Reduced microbial diversity and high abundance of metabolic pathways associated with multidrug-resistance mechanisms characterized the fecal microbiome of patients colonized with MDRO at hospital admission.

Our data suggest that microbial disruption indices may be key to predicting MDRO colonization and could provide novel infection control approaches.

Infect Control Hosp Epidemiol 2017;38:1312–1318