To characterize the relationship between chlorhexidine gluconate (CHG) skin concentration and skin microbial colonization.

Serial cross-sectional study.

Adult patients in medical intensive care units (ICUs) from 7 hospitals; from 1 hospital, additional patients colonized with carbapenemase-producing Enterobacterales (CPE) from both ICU and non-ICU settings. All hospitals performed routine CHG bathing in the ICU.

Skin swab samples were collected from adjacent areas of the neck, axilla, and inguinal region for microbial culture and CHG skin concentration measurement using a semiquantitative colorimetric assay. We used linear mixed effects multilevel models to analyze the relationship between CHG concentration and microbial detection. We explored threshold effects using additional models.

We collected samples from 736 of 759 (97%) eligible ICU patients and 68 patients colonized with CPE. On skin, gram-positive bacteria were cultured most frequently (93% of patients), followed by Candida species (26%) and gram-negative bacteria (20%). The adjusted odds of microbial recovery for every twofold increase in CHG skin concentration were 0.84 (95% CI, 0.80–0.87; P < .001) for gram-positive bacteria, 0.93 (95% CI, 0.89–0.98; P = .008) for Candida species, 0.96 (95% CI, 0.91–1.02; P = .17) for gram-negative bacteria, and 0.94 (95% CI, 0.84–1.06; P = .33) for CPE. A threshold CHG skin concentration for reduced microbial detection was not observed.

On a cross-sectional basis, higher CHG skin concentrations were associated with less detection of gram-positive bacteria and Candida species on the skin, but not gram-negative bacteria, including CPE. For infection prevention, targeting higher CHG skin concentrations may improve control of certain pathogens.

Various water-based heater-cooler devices (HCDs) have been implicated in nontuberculous mycobacteria outbreaks. Ongoing rigorous surveillance for healthcare-associated M. abscessus (HA-Mab) put in place following a prior institutional outbreak of M. abscessus alerted investigators to a cluster of 3 extrapulmonary M. abscessus infections among patients who had undergone cardiothoracic surgery.

Investigators convened a multidisciplinary team and launched a comprehensive investigation to identify potential sources of M. abscessus in the healthcare setting. Adherence to tap water avoidance protocols during patient care and HCD cleaning, disinfection, and maintenance practices were reviewed. Relevant environmental samples were obtained. Patient and environmental M. abscessus isolates were compared using multilocus-sequence typing and pulsed-field gel electrophoresis. Smoke testing was performed to evaluate the potential for aerosol generation and dispersion during HCD use. The entire HCD fleet was replaced to mitigate continued transmission.

Clinical presentations of case patients and epidemiologic data supported intraoperative acquisition. M. abscessus was isolated from HCDs used on patients and molecular comparison with patient isolates demonstrated clonality. Smoke testing simulated aerosolization of M. abscessus from HCDs during device operation. Because the HCD fleet was replaced, no additional extrapulmonary HA-Mab infections due to the unique clone identified in this cluster have been detected.

Despite adhering to HCD cleaning and disinfection strategies beyond manufacturer instructions for use, HCDs became colonized with and ultimately transmitted M. abscessus to 3 patients. Design modifications to better contain aerosols or filter exhaust during device operation are needed to prevent NTM transmission events from water-based HCDs.

To assess whether measurement and feedback of chlorhexidine gluconate (CHG) skin concentrations can improve CHG bathing practice across multiple intensive care units (ICUs).

A before-and-after quality improvement study measuring patient CHG skin concentrations during 6 point-prevalence surveys (3 surveys each during baseline and intervention periods).

The study was conducted across 7 geographically diverse ICUs with routine CHG bathing.

Adult patients in the medical ICU.

CHG skin concentrations were measured at the neck, axilla, and inguinal region using a semiquantitative colorimetric assay. Aggregate unit-level CHG skin concentration measurements from the baseline period and each intervention period survey were reported back to ICU leadership, which then used routine education and quality improvement activities to improve CHG bathing practice. We used multilevel linear models to assess the impact of intervention on CHG skin concentrations.

We enrolled 681 (93%) of 736 eligible patients; 92% received a CHG bath prior to survey. At baseline, CHG skin concentrations were lowest on the neck, compared to axillary or inguinal regions (P < .001). CHG was not detected on 33% of necks, 19% of axillae, and 18% of inguinal regions (P < .001 for differences in body sites). During the intervention period, ICUs that used CHG-impregnated cloths had a 3-fold increase in patient CHG skin concentrations as compared to baseline (P < .001).

Routine CHG bathing performance in the ICU varied across multiple hospitals. Measurement and feedback of CHG skin concentrations can be an important tool to improve CHG bathing practice.

To describe the epidemiology of complex colon surgical procedures (COLO), stratified by present at time of surgery (PATOS) surgical-site infections (SSIs) and non-PATOS SSIs and their impact on the epidemiology of colon-surgery SSIs.

Retrospective cohort study.

SSI data were prospectively collected from patients undergoing colon surgical procedures (COLOs) as defined by the National Healthcare Safety Network (NHSN) at 34 community hospitals in the southeastern United States from January 2015 to June 2019. Logistic regression models identified specific characteristics of complex COLO SSIs, complex non-PATOS COLO SSIs, and complex PATOS COLO SSIs.

Over the 4.5-year study period, we identified 720 complex COLO SSIs following 28,188 COLO surgeries (prevalence rate, 2.55 per 100 procedures). Overall, 544 complex COLO SSIs (76%) were complex non-PATOS COLO SSIs (prevalence rate [PR], 1.93 per 100 procedures) and 176 (24%) complex PATOS COLO SSIs (PR, 0.62 per 100 procedures). Age >75 years and operation duration in the >75th percentile were independently associated with non-PATOS SSIs but not PATOS SSIs. Conversely, emergency surgery and hospital volume for COLO procedures were independently associated with PATOS SSIs but not non-PATOS SSIs. The proportion of polymicrobial SSIs was significantly higher for non-PATOS SSIs compared with PATOS SSIs.

Complex PATOS COLO SSIs have distinct features from complex non-PATOS COLO SSIs. Removal of PATOS COLO SSIs from public reporting allows more accurate comparisons among hospitals that perform different case mixes of colon surgeries.

Sparse recent data are available on the epidemiology of surgical site infections (SSIs) in community hospitals. Our objective was to provide updated epidemiology data on complex SSIs in community hospitals and to characterize trends of SSI prevalence rates over time.

Retrospective cohort study.

SSI data were collected from patients undergoing 26 commonly performed surgical procedures at 32 community hospitals in the southeastern United States from 2013 to 2018. SSI prevalence rates were calculated for each year and were stratified by procedure and causative pathogen.

Over the 6-year study period, 3,561 complex (deep incisional or organ-space) SSIs occurred following 669,467 total surgeries (prevalence rate, 0.53 infections per 100 procedures). The overall complex SSI prevalence rate did not change significantly during the study period: 0.58 of 100 procedures in 2013 versus 0.53 of 100 procedures in 2018 (prevalence rate ratio [PRR], 0.84; 95% CI, 0.66–1.08; P = .16). Methicillin-sensitive Staphylococcus aureus (MSSA) complex SSIs (n = 480, 13.5%) were more common than complex SSIs caused by methicillin-resistant S. aureus (MRSA; n = 363, 10.2%).

The complex SSI rate did not decrease in our cohort of community hospitals from 2013 to 2018, which is a change from prior comparisons. The reason for this stagnation is unclear. Additional research is needed to determine the proportion of or remaining SSIs that are preventable and what measures would be effective to further reduce SSI rates.

The reported incidence of Clostridoides difficile infection (CDI) has increased in recent years, partly due to broadening adoption of nucleic acid amplification tests (NAATs) replacing enzyme immunoassay (EIA) methods. Our aim was to quantify the impact of this switch on reported CDI rates using a large, multihospital, empirical dataset.

We analyzed 9 years of retrospective CDI data (2009–2017) from 47 hospitals in the southeastern United States; 37 hospitals switched to NAAT during this period, including 24 with sufficient pre- and post-switch data for statistical analyses. Poisson regression was used to quantify the NAAT-over-EIA incidence rate ratio (IRR) at hospital and network levels while controlling for longitudinal trends, the proportion of intensive care unit patient days, changes in surveillance methodology, and previously detected infection cluster periods. We additionally used change-point detection methods to identify shifts in the mean and/or slope of hospital-level CDI rates, and we compared results to recorded switch dates.

For hospitals that transitioned to NAAT, average unadjusted CDI rates increased substantially after the test switch from 10.9 to 23.9 per 10,000 patient days. Individual hospital IRRs ranged from 0.75 to 5.47, with a network-wide IRR of 1.75 (95% confidence interval, 1.62–1.89). Reported CDI rates significantly changed 1.6 months on average after switching to NAAT testing (standard deviation, 1.9 months).

Hospitals that switched from EIA to NAAT testing experienced an average postswitch increase of 75% in reported CDI rates after adjusting for other factors, and this increase was often gradual or delayed.

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

To describe the epidemiology of complex surgical site infection (SSI) following commonly performed surgical procedures in community hospitals and to characterize trends of SSI prevalence rates over time for MRSA and other common pathogens

We prospectively collected SSI data at 29 community hospitals in the southeastern United States from 2008 through 2012. We determined the overall prevalence rates of SSI for commonly performed procedures during this 5-year study period. For each year of the study, we then calculated prevalence rates of SSI stratified by causative organism. We created log-binomial regression models to analyze trends of SSI prevalence over time for all pathogens combined and specifically for MRSA.

A total of 3,988 complex SSIs occurred following 532,694 procedures (prevalence rate, 0.7 infections per 100 procedures). SSIs occurred most frequently after small bowel surgery, peripheral vascular bypass surgery, and colon surgery. Staphylococcus aureus was the most common pathogen. The prevalence rate of SSI decreased from 0.76 infections per 100 procedures in 2008 to 0.69 infections per 100 procedures in 2012 (prevalence rate ratio [PRR], 0.90; 95% confidence interval [CI], 0.82–1.00). A more substantial decrease in MRSA SSI (PRR, 0.69; 95% CI, 0.54–0.89) was largely responsible for this overall trend.

The prevalence of MRSA SSI decreased from 2008 to 2012 in our network of community hospitals. This decrease in MRSA SSI prevalence led to an overall decrease in SSI prevalence over the study period.

Infect Control Hosp Epidemiol 2016;37:519–526

To determine the association (1) between shorter operative duration and surgical site infection (SSI) and (2) between surgeon median operative duration and SSI risk among first-time hip and knee arthroplasties.

Retrospective cohort study

A total of 43 community hospitals located in the southeastern United States.

Adults who developed SSIs according to National Healthcare Safety Network criteria within 365 days of first-time knee or hip arthroplasties performed between January 1, 2008 and December 31, 2012.

Log-binomial regression models estimated the association (1) between operative duration and SSI outcome and (2) between surgeon median operative duration and SSI outcome. Hip and knee arthroplasties were evaluated in separate models. Each model was adjusted for American Society of Anesthesiology score and patient age.

A total of 25,531 hip arthroplasties and 42,187 knee arthroplasties were included in the study. The risk of SSI in knee arthroplasties with an operative duration shorter than the 25th percentile was 0.40 times the risk of SSI in knee arthroplasties with an operative duration between the 25th and 75th percentile (risk ratio [RR], 0.40; 95% confidence interval [CI], 0.38–0.56; P<.01). Short operative duration did not demonstrate significant association with SSI for hip arthroplasties (RR, 1.04; 95% CI, 0.79–1.37; P=.36). Knee arthroplasty surgeons with shorter median operative durations had a lower risk of SSI than surgeons with typical median operative durations (RR, 0.52; 95% CI, 0.43–0.64; P<.01).

Short operative durations were not associated with a higher SSI risk for knee or hip arthroplasty procedures in our analysis.

Infect. Control Hosp. Epidemiol. 2015;36(12):1431–1436

To evaluate seasonal variation in the rate of surgical site infections (SSI) following commonly performed surgical procedures.

Retrospective cohort study.

We analyzed 6 years (January 1, 2007, through December 31, 2012) of data from the 15 most commonly performed procedures in 20 hospitals in the Duke Infection Control Outreach Network. We defined summer as July through September. First, we performed 3 separate Poisson regression analyses (unadjusted, multivariable, and polynomial) to estimate prevalence rates and prevalence rate ratios of SSI following procedures performed in summer versus nonsummer months. Then, we stratified our results to obtain estimates based on procedure type and organism type. Finally, we performed a sensitivity analysis to test the robustness of our findings.

We identified 4,543 SSI following 441,428 surgical procedures (overall prevalence rate, 1.03/100 procedures). The rate of SSI was significantly higher during the summer compared with the remainder of the year (1.11/100 procedures vs 1.00/100 procedures; prevalence rate ratio, 1.11 [95% CI, 1.04–1.19]; P=.002). Stratum-specific SSI calculations revealed higher SSI rates during the summer for both spinal (P=.03) and nonspinal (P=.004) procedures and revealed higher rates during the summer for SSI due to either gram-positive cocci (P=.006) or gram-negative bacilli (P=.004). Multivariable regression analysis and sensitivity analyses confirmed our findings.

The rate of SSI following commonly performed surgical procedures was higher during the summer compared with the remainder of the year. Summer SSI rates remained elevated after stratification by organism and spinal versus nonspinal surgery, and rates did not change after controlling for other known SSI risk factors.

Infect. Control Hosp. Epidemiol. 2015;36(9):1011–1016

Hospitals in the National Healthcare Safety Network began reporting laboratory-identified (LabID) Clostridium difficile infection (CDI) events in January 2013. Our study quantified the differences between the LabID and traditional surveillance methods.

Cohort study.

A cohort of 29 community hospitals in the southeastern United States.

A period of 6 months (January 1, 2013, to June 30, 2013) of prospectively collected data using both LabID and traditional surveillance definitions were analyzed. CDI events with mismatched surveillance categories between LabID and traditional definitions were identified and characterized further. Hospital-onset CDI (HO-CDI) rates for the entire cohort of hospitals were calculated using each method, then hospital-specific HO-CDI rates and standardized infection ratios (SIRs) were calculated. Hospital rankings based on each CDI surveillance measure were compared.

A total of 1,252 incident LabID CDI events were identified during 708,551 patient-days; 286 (23%) mismatched CDI events were detected. The overall HO-CDI rate was 6.0 vs 4.4 per 10,000 patient-days for LabID and traditional surveillance, respectively (P<.001); of 29 hospitals, 25 (86%) detected a higher CDI rate using LabID compared with the traditional method. Hospital rank in the cohort differed greatly between surveillance measures. A rank change of at least 5 places occurred in 9 of 28 hospitals (32%) between LabID and traditional CDI surveillance methods, and for SIR.

LabID surveillance resulted in a higher hospital-onset CDI incidence rate than did traditional surveillance. Hospital-specific rankings varied based on the HO-CDI surveillance measure used. A clear understanding of differences in CDI surveillance measures is important when interpreting national and local CDI data.

Infect Control Hosp Epidemiol 2014;00(0): 1–7