As mandatory public reporting of healthcare-associated infections increases, there is concern that clinicians could attempt to decrease rates by avoiding the diagnosis of reportable infections.

To determine whether blood culture and antibiotic utilization changed after mandatory public reporting of central line–associated bloodstream infection (CLABSI).

Interrupted time-series of blood culture and antibiotic rates before and after state-specific implementation of mandatory public reporting. We analyzed data from pediatric and neonatal intensive care units (ICUs) at 17 children’s hospitals that contributed to the Pediatric Health Information System administrative database. We used multivariable regression with generalized linear mixed-effects models to determine adjusted rate ratios (ARRs) after implementation of mandatory public reporting. We conducted subgroup analysis on patients with central venous catheters. To assess temporal trends, we separately analyzed data from 4 pediatric hospitals in states without mandatory public reporting.

There was no significant effect of mandatory public reporting on rates of blood culture (pediatric ICU ARR, 1.03 [95% CI, 0.82–1.28]; neonatal ICU ARR, 1.06 [0.85–1.33]) or antibiotic utilization (pediatric ICU ARR, 0.86 [0.72–1.04]; neonatal ICU ARR, 1.09 [0.87–1.35]). Results were similar in the subgroup of patients with central venous catheter codes. Hospitals with and without mandatory public reporting experienced small decreases in blood culture and antibiotic use across the study period.

Mandatory public reporting of central line–associated bloodstream infection did not impact blood culture and antibiotic utilization, suggesting that clinicians have not shifted their practice in an attempt to detect fewer infections.

Infect Control Hosp Epidemiol 2015;36(8):878–885

To explore the economic impact to a hospital of universal methicillin-resistant Staphylococcus aureus (MRSA) screening.

We used a decision tree model to estimate the direct economic impact to an individual hospital of starting universal MRSA screening and contact precautions. Projected costs and benefits were based on literature-derived data. Our model examined outcomes of several strategies including non-nares MRSA screening and comparison of culture versus polymerase chain reaction–based screening.

Under baseline conditions, the costs of universal MRSA screening and contact precautions outweighed the projected benefits generated by preventing MRSA-related infections, resulting in economic costs of $104,000 per 10,000 admissions (95% CI, $83,000–$126,000). Cost-savings occurred only when the model used estimates at the extremes of our key parameters. Non-nares screening and polymerase chain reaction–based testing, both of which identified more MRSA-colonized persons, resulted in more MRSA infections averted but increased economic costs of the screening program.

We found that universal MRSA screening, although providing potential benefit in preventing MRSA infection, is relatively costly and may be economically burdensome for a hospital. Policy makers should consider the economic burden of MRSA screening and contact precautions in relation to other interventions when choosing programs to improve patient safety and outcomes.

Infect Control Hosp Epidemiol 2015;36(1): 2–13

Hospital environments influence healthcare-associated infection (HAI) patterns, but the role of evidenced-based design (EBD) and residual bacterial DNA (previously thought to be clinically inert) remain incompletely understood.

In a newly built EBD hospital, we used culture-based and culture-free (molecular) assays, pulsed-field gel electrophoresis (PFGE), and whole-genome sequencing (WGS) to determine: (1) patterns of environmental contamination with target organisms (TOs) and multidrug-resistant (MDR) target organisms (MDR-TOs); (2) genetic relatedness between environmentally isolated MDR-TO and those from HAIs; and (3) correlation between surface contamination and HAIs.

A total of 1,273 high-touch surfaces were swabbed before and after terminal cleaning during 77 room visits. Of the 2,546 paired swabs, 47% had cultivable biomaterial and 42% had PCR-amplifiable DNA. The ratios of TOs detected to surfaces assayed were 85 per 1,273 for the culture-based method and 106 per 1,273 for the PCR-based method. Sinks, toilet rails, and bedside tables most frequently harbored biomaterial. Although cleaned surfaces were less likely to have cultivable TOs than precleaned surfaces, they were not less likely to harbor bacterial DNA. The rate of MDR-TOs to surfaces swabbed was 0.1% (3/2546). Although environmental MDR-TOs and MDR-TOs from HAIs were genetically related by PFGE, WGS revealed that they were unrelated. Environmental levels of cultivable Enterococcus spp. and E. coli DNA were positively correlated with infection incidences (P<.04 and P<.005, respectively).

MDR-TOs were rarely detected during surveillance and were not implicated in HAIs. The roles of environmental DNA and EBD, particularly with respect to water-associated fixtures or the potential suppression of cultivable environmental MDR-TOs, warrant multicenter investigations.

Infect Control Hosp Epidemiol 2015;36(10):1130–1138

To examine the prevalence of healthcare-associated pathogens and the infection control policies and practices in a national sample of nursing homes (NHs).

In 2012, we conducted a national survey about the extent to which NHs follow suggested infection control practices with regard to 3 common healthcare-associated pathogens: methicillin-resistant Staphylococcus aureus, Clostridium difficile, and extended-spectrum β-lactamase producers, and their prevalence in NHs. We adapted a previously used and validated NH infection control survey, including questions on prevalence, admission and screening policies, contact precautions, decolonization, and cleaning practices.

A total of 1,002 surveys were returned. Of the responding NHs, 14.2% were less likely to accept residents with methicillin-resistant Staphylococcus aureus, with the principal reason being lack of single or cohort rooms. NHs do not routinely perform admission screening (96.4%) because it is not required by regulation (56.2%) and would not change care provision (30.7%). Isolation strategies vary substantially, with gloves being most commonly used. Most NHs (75.1%) do not decolonize carriers of methicillin-resistant Staphylococcus aureus, but some (10.6%) decolonize more than 90% of residents. Despite no guidance on how resident rooms on contact precautions should be cleaned, 59.3% of NHs report enhanced cleaning for such rooms.

Overall, NHs tend to follow voluntary infection control guidelines only if doing so does not require substantial financial investment in new or dedicated staff or infrastructure.

Infect Control Hosp Epidemiol 2015;36(7):759–766

Targeted surveillance has focused on device-associated infections and surgical site infections (SSIs) and is often limited to healthcare-associated infections (HAIs) in high-risk areas. Longitudinal trends in all HAIs, including other types of HAIs, and HAIs outside of intensive care units (ICUs) remain unclear. We examined the incidences of all HAIs using comprehensive hospital-wide surveillance over a 12-year period (2001–2012).

This retrospective observational study was conducted at the University of North Carolina (UNC) Hospitals, a tertiary care academic facility. All HAIs, including 5 major infections with 14 specific infection sites as defined using CDC criteria, were ascertained through comprehensive hospital-wide surveillance. Generalized linear models were used to examine the incidence rate difference by infection type over time.

A total of 16,579 HAIs included 6,397 cases in ICUs and 10,182 cases outside ICUs. The incidence of overall HAIs decreased significantly hospital-wide (−3.4 infections per 1,000 patient days), in ICUs (−8.4 infections per 1,000 patient days), and in non-ICU settings (−1.9 infections per 1,000 patient days). The incidences of bloodstream infection, urinary tract infection, and pneumonia in hospital-wide settings decreased significantly, but the incidences of SSI and lower respiratory tract infection remained unchanged. The incidence of Clostridium difficile infection (CDI) increased remarkably. The outcomes were estimated to include 700 overall HAIs prevented, 40 lives saved, and cost savings in excess of $10 million.

We demonstrated success in reducing overall HAIs over a 12-year period. Our data underscore the necessity for surveillance and infection prevention interventions outside of the ICUs, for non–device-associated HAIs, and for CDI.

Infect Control Hosp Epidemiol 2015;36(10):1139–1147

Clostridium difficile infection (CDI) has been extensively described in healthcare settings; however, risk factors associated with community-acquired (CA) CDI remain uncertain. This study aimed to synthesize the current evidence for an association between commonly prescribed medications and comorbidities with CA-CDI.

A systematic search was conducted in 5 electronic databases for epidemiologic studies that examined the association between the presence of comorbidities and exposure to medications with the risk of CA-CDI. Pooled odds ratios were estimated using 3 meta-analytic methods. Subgroup analyses by location of studies and by life stages were conducted.

Twelve publications (n=56,776 patients) met inclusion criteria. Antimicrobial (odds ratio, 6.18; 95% CI, 3.80–10.04) and corticosteroid (1.81; 1.15–2.84) exposure were associated with increased risk of CA-CDI. Among the comorbidities, inflammatory bowel disease (odds ratio, 3.72; 95% CI, 1.52–9.12), renal failure (2.64; 1.23–5.68), hematologic cancer (1.75; 1.02–5.68), and diabetes mellitus (1.15; 1.05–1.27) were associated with CA-CDI. By location, antimicrobial exposure was associated with a higher risk of CA-CDI in the United States, whereas proton-pump inhibitor exposure was associated with a higher risk in Europe. By life stages, the risk of CA-CDI associated with antimicrobial exposure greatly increased in adults older than 65 years.

Antimicrobial exposure was the strongest risk factor associated with CA-CDI. Further studies are required to investigate the risk of CA-CDI associated with medications commonly prescribed in the community. Patients with diarrhea who have inflammatory bowel disease, renal failure, hematologic cancer, or diabetes are appropriate populations for interventional studies of screening.

Infect Control Hosp Epidemiol 2014;00(0):1–10

To determine whether central line–associated bloodstream infections (CLABSIs) increase the likelihood of readmission.

Retrospective matched cohort study for the years 2008–2009.

Acute care hospitals.

Medicare recipients. CLABSI and readmission status were determined by linking National Healthcare Safety Network surveillance data to the Centers for Medicare and Medicaid Services’ Medical Provider and Analysis Review in 8 states. Frequency matching was used on International Classification of Diseases, Ninth Revision, Clinical Modification procedure code category and intensive care unit status.

We compared the rate of readmission among patients with and without CLABSI during an index hospitalization. Cox proportional hazard analysis was used to assess rate of readmission (the first hospitalization within 30 days after index discharge). Multivariate models included the following covariates: race, sex, length of index hospitalization stay, central line procedure code, Gagne comorbidity score, and individual chronic conditions.

Of the 8,097 patients, 2,260 were readmitted within 30 days (27.9%). The rate of first readmission was 7.1 events/person-year for CLABSI patients and 4.3 events/person-year for non-CLABSI patients (P<.001). The final model revealed a small but significant increase in the rate of 30-day readmissions for patients with a CLABSI compared with similar non-CLABSI patients. In the first readmission for CLABSI patients, we also observed an increase in diagnostic categories consistent with CLABSI, including septicemia and complications of a device.

Our analysis found a statistically significant association between CLABSI status and readmission, suggesting that CLABSI may have adverse health impact that extends beyond hospital discharge.

Infect Control Hosp Epidemiol 2015;36(8):886–892

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

Staphylococcus aureus carriage among healthcare workers (HCWs) is a concern in hospital settings, where it may provide a reservoir for later infections in both patients and staff. Earlier studies have shown that the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) carriage in HCWs is highly variable, depending notably on location, hospital department type, MRSA prevalence among patients, and type of contacts with patients. However, MRSA incidence in HCWs and its occupational determinants have seldom been studied.

A prospective, observational cohort study was conducted between May and October 2009 in a French rehabilitation center hospital. HCWs and patients were screened weekly for S. aureus nasal carriage. Methicillin-susceptible S. aureus and MRSA prevalence and incidence were estimated and factors associated with MRSA acquisition were identified using generalized estimating equation regression methods.

Among 343 HCWs included in the analysis, the average prevalence was 27% (95% CI, 24%–29%) for methicillin-susceptible S. aureus and 10% (8%–11%) for MRSA. We observed 129 MRSA colonization events. According to the multivariable analysis, high MRSA prevalence level among patients and HCW occupation were significantly associated with MRSA acquisition in HCWs, with assistant nurses being more at risk than nurses (odds ratio, 2.2; 95% CI, 1.4–3.6).

Our findings may help further our understanding of the transmission dynamics of MRSA carriage acquisition in HCWs, suggesting that it is notably driven by carriage among patients and by the type of contact with patients.

Infect Control Hosp Epidemiol 2015;36(7):767–776

To better understand tuberculosis (TB) infection control (IC) in healthcare facilities (HCFs) in Georgia.

A cross-sectional evaluation of healthcare worker (HCW) knowledge, beliefs and behaviors toward TB IC measures including latent TB infection (LTBI) screening and treatment of HCWs.

Georgia, a high-burden multidrug-resistant TB (MDR-TB) country.

HCWs from the National TB Program and affiliated HCFs.

An anonymous self-administered 55-question survey developed based on the Health Belief Model (HBM) conceptual framework.

In total, 240 HCWs (48% physicians; 39% nurses) completed the survey. The overall average TB knowledge score was 61%. Only 60% of HCWs reported frequent use of respirators when in contact with TB patients. Only 52% of HCWs were willing to undergo annual LTBI screening; 48% were willing to undergo LTBI treatment. In multivariate analysis, HCWs who worried about acquiring MDR-TB infection (adjusted odds ratio [aOR], 1.7; 95% confidence interval [CI], 1.28–2.25), who thought screening contacts of TB cases is important (aOR, 3.4; 95% CI, 1.35–8.65), and who were physicians (aOR, 1.7; 95% CI, 1.08–2.60) were more likely to accept annual LTBI screening. With regard to LTBI treatment, HCWs who worked in an outpatient TB facility (aOR, 0.3; 95% CI, 0.11–0.58) or perceived a high personal risk of TB reinfection (aOR, 0.5; 95% CI, 0.37–0.64) were less likely to accept LTBI treatment.

The concern about TB reinfection is a major barrier to HCW acceptance of LTBI treatment. TB IC measures must be strengthened in parallel with or prior to the introduction of LTBI screening and treatment of HCWs.

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

The major mechanism of fluoroquinolone (FQ) resistance in Pseudomonas aeruginosa (PSA) is modification of target proteins in DNA gyrase and topoisomerase IV, most commonly the gyrA and parC subunits. The objective of this study was to determine risk factors for PSA with and without gyrA or parC mutations.

Case-case-control study

Two adult academic acute-care hospitals

Case 1 study participants had a PSA isolate on hospital day 3 or later with any gyrA or parC mutation; case 2 study participants had a PSA isolate on hospital day 3 or later without these mutations. Controls were a random sample of all inpatients with a stay of 3 days or more.

Each case group was compared to the control group in separate multivariate models on the basis of demographics and inpatient antibiotic exposure, and risk factors were qualitatively compared.

Of 298 PSA isolates, 172 (57.7%) had at least 1 mutation. Exposure to vancomycin and other agents with extended Gram-positive activity was a risk factor for both cases (case 1 odds ratio [OR], 1.09; 95% confidence interval [CI], 1.04–1.13; OR, 1.14; 95% CI, 1.03–1.26; case 2 OR, 1.09; 95% CI, 1.03–1.14; OR, 1.13; 95% CI, 1.01–1.25, respectively).

Exposure to agents with extended Gram-positive activity is a risk factor for isolation of PSA overall but not for gyrA/parC mutations. FQ exposure is not associated with isolation of PSA with mutations.

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

Contact patterns and microbiological data contribute to a detailed understanding of infectious disease transmission. We explored the automated collection of high-resolution contact data by wearable sensors combined with virological data to investigate influenza transmission among patients and healthcare workers in a geriatric unit.

Proof-of-concept observational study. Detailed information on contact patterns were collected by wearable sensors over 12 days. Systematic nasopharyngeal swabs were taken, analyzed for influenza A and B viruses by real-time polymerase chain reaction, and cultured for phylogenetic analysis.

An acute-care geriatric unit in a tertiary care hospital.

Patients, nurses, and medical doctors.

A total of 18,765 contacts were recorded among 37 patients, 32 nurses, and 15 medical doctors. Most contacts occurred between nurses or between a nurse and a patient. Fifteen individuals had influenza A (H3N2). Among these, 11 study participants were positive at the beginning of the study or at admission, and 3 patients and 1 nurse acquired laboratory-confirmed influenza during the study. Infectious medical doctors and nurses were identified as potential sources of hospital-acquired influenza (HA-Flu) for patients, and infectious patients were identified as likely sources for nurses. Only 1 potential transmission between nurses was observed.

Combining high-resolution contact data and virological data allowed us to identify a potential transmission route in each possible case of HA-Flu. This promising method should be applied for longer periods in larger populations, with more complete use of phylogenetic analyses, for a better understanding of influenza transmission dynamics in a hospital setting.

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

To determine whether use of contact precautions on hospital ward patients is associated with patient adverse events

Individually matched prospective cohort study

The University of Maryland Medical Center, a tertiary care hospital in Baltimore, Maryland

A total of 296 medical or surgical inpatients admitted to non–intensive care unit hospital wards were enrolled at admission from January to November 2010. Patients on contact precautions were individually matched by hospital unit after an initial 3-day length of stay to patients not on contact precautions. Adverse events were detected by physician chart review and categorized as noninfectious, preventable and severe noninfectious, and infectious adverse events during the patient’s stay using the standardized Institute for Healthcare Improvement’s Global Trigger Tool.

The cohort of 148 patients on contact precautions at admission was matched with a cohort of 148 patients not on contact precautions. Of the total 296 subjects, 104 (35.1%) experienced at least 1 adverse event during their hospital stay. Contact precautions were associated with fewer noninfectious adverse events (rate ratio [RtR], 0.70; 95% confidence interval [CI], 0.51–0.95; P=.02) and although not statistically significant, with fewer severe adverse events (RtR, 0.69; 95% CI, 0.46–1.03; P=.07). Preventable adverse events did not significantly differ between patients on contact precautions and patients not on contact precautions (RtR, 0.85; 95% CI, 0.59–1.24; P=.41).

Hospital ward patients on contact precautions were less likely to experience noninfectious adverse events during their hospital stay than patients not on contact precautions.

Infect. Control Hosp. Epidemiol. 2015;36(11):1268–1274

The Centers for Disease Control and Prevention (CDC) has developed an approach to ventilator-associated events (VAE) surveillance. Using these methods, this study was performed to investigate VAE incidences and to test whether VAEs are associated with poorer outcomes in China.

A 4-month, prospective multicenter surveillance study between April and July 2013.

Our study included 15 adult intensive care units (ICUs) of 15 hospitals in China.

Patients admitted to ICUs during the study period

Patients on mechanical ventilation (MV) were monitored for VAEs: ventilator-associated conditions (VACs), infection-related ventilator-associated complications (IVACs), and possible or probable ventilator-associated pneumonia (VAP). Patients with and without VACs were compared with regard to duration of MV, ICU length of stay (LOS), overall hospital LOS, and mortality rate.

During the study period, 2,356 of the 5,256 patients admitted to ICUs received MV for 8,438 ventilator days. Of these patients, 636 were on MV >2 days. VACs were identified in 94 cases (4.0%; 11.1 cases per 1,000 ventilator days), including 31 patients with IVACs and 16 with possible VAP but none with probable VAP. Compared with patients without VACs, patients with VACs had longer ICU LOS (by 6.2 days), longer duration on MV (by 7.7 days), and higher hospital mortality rate (50.0% vs 27.3%). The mortality rate attributable to VACs was 11.7%. Compared with those with VACs alone, patients with IVACs had longer duration on MV and increased ICU LOS but no higher mortality rates.

In China, surveillance of VACs and IVACs is able to identify MV patients with poorer outcomes. However, surveillance of possible and probable VAP can be problematic.

Infect. Control Hosp. Epidemiol. 2015;36(12):1388–1395

To describe the use of antimicrobial stewardship policies and to investigate factors associated with implementation in a national sample of acute care hospitals.

Cross-sectional survey.

Infection Control Directors from acute care hospitals participating in the National Healthcare Safety Network (NHSN).

An online survey was conducted in the Fall of 2011. A subset of hospitals also provided access to their 2011 NHSN annual survey data.

Responses were received from 1,015 hospitals (30% response rate). The majority of hospitals (64%) reported the presence of a policy; use of antibiograms and antimicrobial restriction policies were most frequently utilized (83% and 65%, respectively). Respondents from larger, urban, teaching hospitals and those that are part of a system that shares resources were more likely to report a policy in place (P<.01). Hospitals located in California were more likely to have policy in place than in hospitals located in other states (P=.014).

This study provides a snapshot of the implementation of antimicrobial stewardship policies in place in U.S. hospitals and suggests that statewide efforts in California are achieving their intended effect. Further research is needed to identify factors that foster the adoption of these policies.

Infect Control Hosp Epidemiol 2014;00(0): 1–4

To evaluate the quality of gastrointestinal endoscope reprocessing and discuss the advantages of microbiological surveillance testing of these endoscopes.

Retrospective analysis of the results of endoscope sampling performed from October 1, 2006, through December 31, 2014, in a gastrointestinal endoscopy unit of a teaching hospital equipped with 89 endoscopes and 3 automated endoscope reprocessors, with an endoscopy quality assurance program in place. The compliance rate was defined as the proportion of the results classified at target or alert levels according to the French guidelines. A multivariate analysis (logistic regression) was used to identify the parameters influencing compliance.

A total of 846 samples were taken. The overall compliance rate was 86% and differed significantly depending on the sampling context (scheduled or not scheduled), the type of endoscope, and the season. No other parameter was associated with compliance. A total of 118 samples carried indicator microorganisms such as Pseudomonas aeruginosa, Stenotrophomonas maltophilia, Enterobacteriaceae, and Candida sp.

The systematic use of an automated endoscope reprocessor does not provide totally satisfactory compliance. Microbiological surveillance is indispensable to monitor reprocessing, reinforce good practices (endoscopes, reprocessing units), and detect endoscopes requiring early technical maintenance.

Infect. Control Hosp. Epidemiol. 2015;36(9):1017–1023

We identified an outbreak of AmpC–producing Escherichia coli infections resistant to third-generation cephalosporins and carbapenems (CR) among 7 patients who had undergone endoscopic retrograde cholangiopancreatography at hospital A during November 2012–August 2013. Gene sequencing revealed a shared novel mutation in a blaCMY gene and a distinctive fumC/ fimH typing profile.

To determine the extent and epidemiologic characteristics of the outbreak, identify potential sources of transmission, design and implement infection control measures, and determine the association between the CR E. coli and AmpC E. coli circulating at hospital A.

We reviewed laboratory, medical, and endoscopy reports, and endoscope reprocessing procedures. We obtained cultures from endoscopes after reprocessing as well as environmental samples and conducted pulsed-field gel electrophoresis and gene sequencing on phenotypic AmpC isolates from patients and endoscopes. Cases were those infected with phenotypic AmpC isolates (both carbapenem-susceptible and CR) and identical blaCMY-2, fumC, and fimH alleles or related pulsed-field gel electrophoresis patterns.

Thirty-five of 49 AmpC E. coli tested met the case definition, including all CR isolates. All cases had complicated biliary disease and had undergone at least 1 endoscopic retrograde cholangiopancreatography at hospital A. Mortality at 30 days was 16% for all patients and 56% for CR patients. Two of 8 reprocessed endoscopic retrograde cholangiopancreatography scopes harbored AmpC that matched case isolates by pulsed-field gel electrophoresis. Environmental cultures were negative. No breaches in infection control were identified. Endoscopic reprocessing exceeded manufacturer’s recommended cleaning guidelines.

Recommended reprocessing guidelines are not sufficient.

Infect Control Hosp Epidemiol 2015;00(0): 1–9

Infants in the neonatal intensive care unit (NICU) are at increased risk for methicillin-resistant Staphylococcus aureus (MRSA) acquisition. Outbreaks may be difficult to identify due in part to limitations in current molecular genotyping available in clinical practice. Comparison of genome-wide single nucleotide polymorphisms (SNPs) may identify epidemiologically distinct isolates among a population sample that appears homogenous when evaluated using conventional typing methods.

To investigate a putative MRSA outbreak in a NICU utilizing whole-genome sequencing and phylogenetic analysis to identify recent transmission events.

Clinical and surveillance specimens collected during clinical care and outbreak investigation.

A total of 17 neonates hospitalized in a 43-bed level III NICU in northeastern Florida from December 2010 to October 2011 were included in this study.

We assessed epidemiological data in conjunction with 4 typing methods: antibiograms, PFGE, spa types, and phylogenetic analysis of genome-wide SNPs.

Among the 17 type USA300 isolates, 4 different spa types were identified using pulsed-field gel electrophoresis. Phylogenetic analysis identified 5 infants as belonging to 2 clusters of epidemiologically linked cases and excluded 10 unlinked cases from putative transmission events. The availability of these results during the initial investigation would have improved infection control interventions.

Whole-genome sequencing and phylogenetic analysis are invaluable tools for epidemic investigation; they identify transmission events and exclude cases mistakenly implicated by traditional typing methods. When routinely applied to surveillance and investigation in the clinical setting, this approach may provide actionable intelligence for measured, appropriate, and effective interventions.

Infect. Control Hosp. Epidemiol. 2015;36(7):777–785