To determine the impact of mucosal barrier injury laboratory-confirmed bloodstream infections (MBI-LCBIs) on central-line–associated bloodstream infection (CLABSI) rates during the first year of MBI-LCBI reporting to the National Healthcare Safety Network (NHSN)

Descriptive analysis of 2013 NHSN data

Selected inpatient locations in acute care hospitals

A descriptive analysis of MBI-LCBI cases was performed. CLABSI rates per 1,000 central-line days were calculated with and without the inclusion of MBI-LCBIs in the subset of locations reporting ≥1 MBI-LCBI, and in all locations (regardless of MBI-LCBI reporting) to determine rate differences overall and by location type.

From 418 locations in 252 acute care hospitals reporting ≥1 MBI-LCBIs, 3,162 CLABSIs were reported; 1,415 (44.7%) met the MBI-LCBI definition. Among these locations, removing MBI-LCBI from the CLABSI rate determination produced the greatest CLABSI rate decreases in oncology (49%) and ward locations (45%). Among all locations reporting CLABSI data, including those reporting no MBI-LCBIs, removing MBI-LCBI reduced rates by 8%. Here, the greatest decrease was in oncology locations (38% decrease); decreases in other locations ranged from 1.2% to 4.2%.

An understanding of the potential impact of removing MBI-LCBIs from CLABSI data is needed to accurately interpret CLABSI trends over time and to inform changes to state and federal reporting programs. Whereas the MBI-LCBI definition may have a large impact on CLABSI rates in locations where patients with certain clinical conditions are cared for, the impact of MBI-LCBIs on overall CLABSI rates across inpatient locations appears to be more modest.

Infect. Control Hosp. Epidemiol. 2015;37(1):2–7

To determine the role of unit-based transmission that accounts for cases of early Clostridium difficile infection (CDI) during hospitalization for allogeneic stem cell transplant.

Stem cell transplant unit at a tertiary care cancer center.

Serially collected stool from patients admitted for transplant was screened for toxigenic C. difficile through the hospital stay and genotyping was performed by multilocus sequence typing. In addition, isolates retrieved from cases of CDI that occurred in other patients hospitalized on the same unit were similarly characterized. Transmission links were established by time-space clustering of cases and carriers of shared toxigenic C. difficile strains.

During the 27-month period, 1,099 samples from 264 patients were screened, 69 of which had evidence of toxigenic C. difficile; 52 patients developed CDI and 17 were nonsymptomatic carriers. For the 52 cases, 41 had evidence of toxigenic C. difficile on the first study sample obtained within a week of admission, among which 22 were positive within the first 48 hours. A total of 24 sequence types were isolated from this group; 1 patient had infection with the NAP1 strain. A total of 11 patients had microbiologic evidence of acquisition; donor source could be established in half of these cases.

Most cases of CDI after stem cell transplant represent delayed onset disease in nonsymptomatic carriers. Transmission on stem cell transplant unit was confirmed in 19% of early CDI cases in our cohort with a probable donor source established in half of the cases.

Infect. Control Hosp. Epidemiol. 2015;37(1):8–15

Case mix index (CMI) has been used as a facility-level indicator of patient disease severity. We sought to evaluate the potential for CMI to be used for risk adjustment of National Healthcare Safety Network (NHSN) healthcare-associated infection (HAI) data.

NHSN facility-wide laboratory-identified Clostridium difficile infection event data from 2012 were merged with the fiscal year 2012 Inpatient Prospective Payment System (IPPS) Impact file by CMS certification number (CCN) to obtain a CMI value for hospitals reporting to NHSN. Negative binomial regression was used to evaluate whether CMI was significantly associated with healthcare facility-onset (HO) CDI in univariate and multivariate analysis.

Among 1,468 acute care hospitals reporting CDI data to NHSN in 2012, 1,429 matched by CCN to a CMI value in the Impact file. CMI (median, 1.49; interquartile range, 1.36–1.66) was a significant predictor of HO CDI in univariate analysis (P<.0001). After controlling for community onset CDI prevalence rate, medical school affiliation, hospital size, and CDI test type use, CMI remained highly significant (P<.0001), with an increase of 0.1 point in CMI associated with a 3.4% increase in the HO CDI incidence rate.

CMI was a significant predictor of NHSN HO CDI incidence. Additional work to explore the feasibility of using CMI for risk adjustment of NHSN data is necessary.

Infect. Control Hosp. Epidemiol. 2015;37(1):19–25

Prior data suggest that vancomycin-resistant Enterococcus (VRE) bacteremia is associated with worse outcomes than vancomycin-sensitive Enterococcus (VSE) bacteremia. However, many studies evaluating such outcomes were conducted prior to the availability of effective VRE therapies.

To systematically review VRE and VSE bacteremia outcomes among hospital patients in the era of effective VRE therapy.

Electronic databases and grey literature published between January 1997 and December 2014 were searched to identify all primary research studies comparing outcomes of VRE and VSE bacteremias among hospital patients, following the availability of effective VRE therapies. The primary outcome was all-cause, in-hospital mortality, while total hospital length of stay (LOS) was a secondary outcome. All meta-analyses were conducted in Review Manager 5.3 using random-effects, inverse variance modeling.

Among all the studies reviewed, 12 cohort studies and 1 case control study met inclusion criteria. Similar study designs were combined in meta-analyses for mortality and LOS. VRE bacteremia was associated with increased mortality compared with VSE bacteremia among cohort studies (odds ratio [OR], 1.80; 95% confidence interval [CI], 1.38–2.35; I2=0%; n=11); the case-control study estimate was similar, but not significant (OR, 1.93; 95% CI, 0.97–3.82). LOS was greater for VRE bacteremia patients than for VSE bacteremia patients (mean difference, 5.01 days; 95% CI, 0.58–9.44]; I2=0%; n=5).

Despite the availability of effective VRE therapy, VRE bacteremia remains associated with an increased risk of in-hospital mortality and LOS when compared to VSE bacteremia.

Infect. Control Hosp. Epidemiol. 2015;37(1):26–35

Studies have suggested that contact precautions (CP) for methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococcus may have risks that outweigh the benefits. These risks, coupled with more widespread use of horizontal interventions such as daily bathing with chlorhexidine gluconate, have brought into question the value of routine CP for these organisms.

To assess the state of utilization of CP as well as adjunctive measures to reduce the risk of transmission in US hospitals.

Cross-sectional survey.

Total of 751 physician members of the Emerging Infections Network.

An 8-question electronic survey distributed by email.

A total of 426/751 (57%) responded to the survey; 337/364 (93%) of respondents use routine CP for methicillin-resistant S. aureus and 335/364 (92%) use routine CP for vancomycin-resistant enterococcus. The most widely used trigger for initiation of CP for both pathogens was positive clinical culture. Practices for discontinuation of isolation varied widely. We found that 325/354 (92%) perform routine chlorhexidine gluconate bathing and 236/353 (67%) perform S. aureus decolonization with mupirocin for 1 or more subsets of inpatients, and 82/356 (23%) reported using either hydrogen peroxide vapor or ultraviolet-C room disinfection at discharge. Free text responses noted frustration and variation in the application, practice, and process for initiation and discontinuation of CP.

Use of CP for methicillin-resistant S. aureus and vancomycin-resistant enterococcus remains commonplace, although horizontal interventions such as chlorhexidine gluconate bathing are increasingly used. The heterogeneity of practices and policies was striking. Evidence-based guidelines regarding CP and horizontal interventions are needed.

Infect. Control Hosp. Epidemiol. 2015;37(1):36–40

To assess the clinical effectiveness of a universal screening program compared with a risk factor–based program in reducing the rates of nosocomial methicillin-resistant Staphylococcus aureus (MRSA) among admitted patients at the Ottawa Hospital.

Quasi-experimental study.

Ottawa Hospital, a multicenter tertiary care facility with 3 main campuses, approximately 47,000 admissions per year, and 1,200 beds.

From January 1, 2006 through December 31, 2007 (24 months), admitted patients underwent risk factor–based MRSA screening. From January 1, 2008 through August 31, 2009 (20 months), all patients admitted underwent universal MRSA screening. To measure the effectiveness of this intervention, segmented regression modeling was used to examine monthly nosocomial MRSA incidence rates per 100,000 patient-days before and during the intervention period. To assess secular trends, nosocomial Clostridium difficile infection, mupirocin prescriptions, and regional MRSA rates were investigated as controls.

The nosocomial MRSA incidence rate was 46.79 cases per 100,000 patient-days, with no significant differences before and after intervention. The MRSA detection rate per 1,000 admissions increased from 9.8 during risk factor–based screening to 26.2 during universal screening. A total of 644 new nosocomial MRSA cases were observed in 1,448,488 patient-days, 323 during risk factor–based screening and 321 during universal screening. Secular trends in C. difficile infection rates and mupirocin prescriptions remained stable after the intervention whereas population-level MRSA rates decreased.

At Ottawa Hospital, the introduction of universal MRSA admission screening did not significantly affect the rates of nosocomial MRSA compared with risk factor–based screening.

Infect. Control Hosp. Epidemiol. 2015;37(1):41–48

To describe the epidemiology of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (ESBL-EC) and Klebsiella pneumoniae (ESBL-KP) infections

Retrospective cohort

Inpatient care at community hospitals

All patients with ESBL-EC or ESBL-KP infections

ESBL-EC and ESBL-KP infections from 26 community hospitals were prospectively entered into a centralized database from January 2009 to December 2014.

A total of 925 infections caused by ESBL-EC (10.5 infections per 100,000 patient days) and 463 infections caused by ESBL-KP (5.3 infections per 100,000 patient days) were identified during 8,791,243 patient days of surveillance. The incidence of ESBL-EC infections increased from 5.28 to 10.5 patients per 100,000 patient days during the study period (P=.006). The number of community hospitals with ESBL-EC infections increased from 17 (65%) in 2009 to 20 (77%) in 2014. The median ESBL-EC infection rates among individual hospitals with ≥1 ESBL-EC infection increased from 11.1 infections/100,000 patient days (range, 2.2–33.9 days) in 2009 to 22.1 infections per 100,000 patient days (range, 0.66–134 days) in 2014 (P=.05). The incidence of ESBL-KP infections remained constant over the study period (P=.14). Community-associated and healthcare-associated ESBL-EC infections trended upward (P=.006 and P=.02, respectively), while hospital-onset infections remained stable (P=.07). ESBL-EC infections were more common in females (54% vs 44%, P<.001) and Caucasians (50% vs 40%, P<.0001), and were more likely to be isolated from the urinary tract (61% vs 52%, P<.0001) than ESBL-KP infections.

The incidence of ESBL-EC infection has increased in community hospitals throughout the southeastern United States, while the incidence of ESBL-KP infection has remained stable. Community- and healthcare-associated ESBL-EC infections are driving the upward trend.

Infect. Control Hosp. Epidemiol. 2015;37(1):49–54

An improved understanding of carbapenem-resistant Klebsiella pneumoniae (CRKP) in long-term acute care hospitals (LTACHs) is needed. The objective of this study was to assess risk factors for colonization or infection with CRKP in LTACH residents.

A case-control study was performed at a university-affiliated LTACH from 2008 to 2013. Cases were defined as all patients with clinical cultures positive for CRKP and controls were those with clinical cultures positive for carbapenem-susceptible K. pneumoniae (CSKP). A multivariate model was developed to identify risk factors for CRKP infection or colonization.

A total of 222 patients were identified with K. pneumoniae clinical cultures during the study period; 99 (45%) were case patients and 123 (55%) were control patients. Our multivariate analysis identified factors associated with a significant risk for CRKP colonization or infection: solid organ or stem cell transplantation (OR, 5.05; 95% CI, 1.23–20.8; P=.03), mechanical ventilation (OR, 2.56; 95% CI, 1.24–5.28; P=.01), fecal incontinence (OR, 5.78; 95% CI, 1.52–22.0; P=.01), and exposure in the prior 30 days to meropenem (OR, 3.55; 95% CI, 1.04–12.1; P=.04), vancomycin (OR, 2.94; 95% CI, 1.18–7.32; P=.02), and metronidazole (OR, 4.22; 95% CI, 1.28–14.0; P=.02).

Rates of colonization and infection with CRKP were high in the LTACH setting, with nearly half of K. pneumoniae cultures demonstrating carbapenem resistance. Further studies are needed on interventions to limit the emergence of CRKP in LTACHs, including targeted surveillance screening of high-risk patients and effective antibiotic stewardship measures.

Infect. Control Hosp. Epidemiol. 2015;37(1):55–60

To evaluate the expected and treatment outcomes of Thai infectious disease physicians (IDPs) regarding carbapenem-resistant Acinetobacter baumannii (CRAB) ventilator-associated pneumonia (VAP)

From June 1, 2014, to March 1, 2015, survey data regarding the expected and clinical success rates of CRAB VAP treatment were collected from all Thai IDPs. The expected success rate was defined as the expectation of clinical response after CRAB VAP treatment for the given case scenario. Clinical success rate was defined as the overall reported success rate of CRAB VAP treatment based on the clinical practice of each IDP. The expected and clinical success rates were divided into low (<60%), standard (60%–80%), and high (>80%) categories and were then compared with standard clinical response rates archived in the existing literature.

Of 183 total Thai IDPs, 111 (60%) were enrolled in this study. The median expected and clinical success rates were 68% and 58%, respectively. Using multivariate analysis, we determined that working in a hospital that implemented the standard intervention combined with an intensified infection control (IC) intervention for CRAB (adjusted odds ratio [aOR], 3.01; 95% confidence interval [CI], 1.17–7.73; P=.02) was associated with standard and high expected rates (>60%). Being a board-certified IDP (aOR, 5.76; 95% CI, 2.16–15.37; P<.01) and having higher number of ID consultation cases per month (aOR, 4.84; 95% CI, 1.98–11.80; P<.01) were associated with standard and high clinical success rates (>60%). We identified a significant correlation between expected and clinical success rates (r=0.58; P<.001).

Awareness of IC among IDPs can improve physicians’ expected and clinical success rates for CRAB VAP treatment, and treatment experience impacts overall treatment success.

Infect. Control Hosp. Epidemiol. 2015;37(1):61–69

To design better antimicrobial stewardship programs, detailed data on the primary drivers and patterns of antibiotic use are needed.

To characterize the indications for antibiotic therapy, agents used, duration, combinations, and microbiological justification in 6 acute-care US facilities with varied location, size, and type of antimicrobial stewardship programs.

Retrospective medical chart review was performed on a random cross-sectional sample of 1,200 adult inpatients, hospitalized (>24 hrs) in 6 hospitals, and receiving at least 1 antibiotic dose on 4 index dates chosen at equal intervals through a 1-year study period (October 1, 2009–September 30, 2010).

Infectious disease specialists recorded patient demographic characteristics, comorbidities, microbiological and radiological testing, and agents used, dose, duration, and indication for antibiotic prescriptions.

On the index dates 4,119 (60.5%) of 6,812 inpatients were receiving antibiotics. The random sample of 1,200 case patients was receiving 2,527 antibiotics (average: 2.1 per patient); 540 (21.4%) were prophylactic and 1,987 (78.6%) were therapeutic, of which 372 (18.7%) were pathogen-directed at start. Of the 1,615 empirical starts, 382 (23.7%) were subsequently pathogen-directed and 1,231 (76.2%) remained empirical. Use was primarily for respiratory (27.6% of prescriptions) followed by gastrointestinal (13.1%) infections. Fluoroquinolones, vancomycin, and antipseudomonal penicillins together accounted for 47.1% of therapy-days.

Use of broad-spectrum empirical therapy was prevalent in 6 US acute care facilities and in most instances was not subsequently pathogen directed. Fluoroquinolones, vancomycin, and antipseudomonal penicillins were the most frequently used antibiotics, particularly for respiratory indications.

Infect. Control Hosp. Epidemiol. 2015;37(1):70–79

To use a unique multicomponent administrative data set assembled at a large academic teaching hospital to examine the risk of percutaneous blood and body fluid (BBF) exposures occurring in operating rooms.

A 10-year retrospective cohort design.

A single large academic teaching hospital.

All surgical procedures (n=333,073) performed in 2001–2010 as well as 2,113 reported BBF exposures were analyzed.

Crude exposure rates were calculated; Poisson regression was used to analyze risk factors and account for procedure duration. BBF exposures involving suture needles were examined separately from those involving other device types to examine possible differences in risk factors.

The overall rate of reported BBF exposures was 6.3 per 1,000 surgical procedures (2.9 per 1,000 surgical hours). BBF exposure rates increased with estimated patient blood loss (17.7 exposures per 1,000 procedures with 501–1,000 cc blood loss and 26.4 exposures per 1,000 procedures with >1,000 cc blood loss), number of personnel working in the surgical field during the procedure (34.4 exposures per 1,000 procedures having ≥15 personnel ever in the field), and procedure duration (14.3 exposures per 1,000 procedures lasting 4 to <6 hours, 27.1 exposures per 1,000 procedures lasting ≥6 hours). Regression results showed associations were generally stronger for suture needle–related exposures.

Results largely support other studies found in the literature. However, additional research should investigate differences in risk factors for BBF exposures associated with suture needles and those associated with all other device types.

Infect. Control Hosp. Epidemiol. 2015;37(1):80–87

To determine the independent association between diabetes and surgical site infection (SSI) across multiple surgical procedures.

Systematic review and meta-analysis.

Studies indexed in PubMed published between December 1985 and through July 2015 were identified through the search terms “risk factors” or “glucose” and “surgical site infection.” A total of 3,631 abstracts were identified through the initial search terms. Full texts were reviewed for 522 articles. Of these, 94 articles met the criteria for inclusion. Standardized data collection forms were used to extract study-specific estimates for diabetes, blood glucose levels, and body mass index (BMI). A random-effects meta-analysis was used to generate pooled estimates, and meta-regression was used to evaluate specific hypothesized sources of heterogeneity.

The primary outcome was SSI, as defined by the Centers for Disease Control and Prevention surveillance criteria. The overall effect size for the association between diabetes and SSI was odds ratio (OR)=1.53 (95% predictive interval [PI], 1.11–2.12; I2, 57.2%). SSI class, study design, or patient BMI did not significantly impact study results in a meta-regression model. The association was higher for cardiac surgery 2.03 (95% PI, 1.13–4.05) compared with surgeries of other types (P=.001).

These results support the consideration of diabetes as an independent risk factor for SSIs for multiple surgical procedure types. Continued efforts are needed to improve surgical outcomes for diabetic patients.

Infect. Control Hosp. Epidemiol. 2015;37(1):88–99