Jean M. Pottinger

Basics of Surveillance—An Overview

Surveillance of nosocomial infections is the foundation of an infection control program. This article describes components of a surveillance system, methods for surveillance, methods for case-finding, and data sources. We encourage the epidemiology team to use this background information as they design surveillance systems that meet the goals of their individual institutions infection control program.

Survey of long-term-care facilities in Iowa for policies and practices regarding residents with methicillin-resistant Staphylococcus aureus or vancomycin-resistant enterococci.

OBJECTIVES To identify infection control policies and practices used by long-term-care facilities (LTCFs) in Iowa for residents with methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant enterococci (VRE), and to estimate the prevalence of residents known to have these organisms. DESIGN Survey. SETTING LTCFs in Iowa from December 2002 through March 2003. RESULTS Of the 429 LTCFs in Iowa, 331 (77%) responded to the survey. The estimated prevalence of residents known to have MRSA was 13.4 per 1,000 and that of residents known to have VRE was 2.3 per 1,000. Facilities owned by the government or those with an average of more than 86 occupied beds were more likely to have residents known to have MRSA and VRE (P = .002 and .007, respectively). Of the responding facilities, 7.3% acknowledged that they refused to accept individuals known to have MRSA and 16.9% acknowledged that they refused to accept those known to have VRE. Facilities in large communities (population, > 100,000) were least likely to deny admission to an individual known to have either MRSA or VRE (P = .05). Most facilities reported adhering to the national guidelines, but fewer than half (44.7%) of the respondents had heard of the Iowa Antibiotic Resistance Task Forces guidelines regarding residents with MRSA or VRE. CONCLUSIONS Many LTCFs in Iowa care for residents known to have MRSA or VRE, but some refuse to admit these individuals. Infection control personnel and public health officials should work together to educate LTCF staff so that residents receive proper care and resistant organisms do not spread within this setting.

Clinical significance of positive cranial bone flap cultures and associated risk of surgical site infection after craniotomies or craniectomies.

OBJECT The risk of surgical site infection (SSI) after craniotomies or craniectomies in patients in whom contaminated bone flaps have been reimplanted has not been determined. The objectives of this study were to identify the prevalence of bone flaps with positive cultures--especially those contaminated with Propionibacterium acnes--to assess the risk of SSI after reimplanting (either during the initial operation or subsequently) bone flaps with positive cultures, and to identify risk factors for SSI following the initial craniotomies or craniectomies. METHODS The authors conducted a retrospective review of cases in which patients underwent craniotomy/craniectomy procedures between January and October 2007 in the neurosurgery department at the University of Iowa Hospitals and Clinics. They also reviewed processes and procedures and did pulsed field gel electrophoresis of P. acnes isolates to look for a common source of contamination. They then conducted a prospective cohort study that included all patients who underwent craniotomy/craniectomy procedures between November 2007 and November 2008 and met the study criteria. For the cohort study, the authors obtained cultures from each patients bone flap during the craniotomy/craniectomy procedures. Data about potential risk factors were collected by circulating nurses during the procedures or by a research assistant who reviewed medical records after the procedures. An infection preventionist independently identified SSIs through routine surveillance using the Centers for Disease Control and Preventions definitions. Univariate and bivariate analyses were performed to determine the association between SSI and potential risk factors. RESULTS The retrospective review did not identify specific breaks in aseptic technique or a common source of P. acnes. Three hundred seventy-three patients underwent 393 craniotomy/craniectomy procedures during the cohort study period, of which 377 procedures met the study criteria. Fifty percent of the bone flaps were contaminated by microorganisms, primarily skin flora such as P. acnes, coagulase-negative staphylococci, and Staphylococcus aureus. Reimplanting bone flaps that had positive culture results did not increase the risk of infection after the initial craniotomy/craniectomy procedures and the subsequent cranioplasty procedures (p = 0.80). Allowing the skin antiseptic to dry before the procedures (p = 0.04, OR 0.26) was associated with lower risk of SSIs. Female sex (p = 0.02, OR = 3.49) was associated with an increased risk of SSIs; Gliadel wafer implants (p = 0.001, OR = 8.38) were associated with an increased risk of SSIs after procedures to treat tumors. CONCLUSIONS Operative factors such as the way the skin is prepared before the incision rather than the skin flora contaminants on the bone flaps may play an important role in the pathogenesis of SSIs after craniotomy/craniectomy. Gliadel wafers significantly increased the risk of SSI after procedures to treat tumors.

Benefits of Universal Gloving on Hospital-Acquired Infections in Acute Care Pediatric Units

BACKGROUND: To prevent transmission, some pediatric units require clinicians to wear gloves for all patient contacts during RSV season. We sought to assess whether a mandatory gloving policy reduced the risk of other health care–acquired infections (HAIs). METHODS: This retrospective cohort study included all patients admitted to pediatric units of a tertiary care center between 2002 and 2010. Poisson regression models were used to measure the association between mandatory gloving and HAI incidence. Autoregressive models were used to adjust for time correlation. RESULTS: During the study period, 686 HAIs occurred during 363 782 patient-days. The risk of any HAI was 25% lower during mandatory gloving periods compared with during nongloving periods (relative risk [RR]: 0.75; 95% confidence interval [CI]: 0.69–0.93; P = .01), after adjusting for long-term trends and seasonal effect. Mandatory gloving was associated with lower risks of bloodstream infections (RR: 0.63; 95% CI: 0.49–0.81; P < .001), central line–associated bloodstream infections (RR: 0.61; 95% CI: 0.44–0.84; P = 0.003), and hospital-acquired pneumonia (RR: 0.20; 95% CI: 0.03–1.25; P= 0.09). The reduction was significant in the PICU (RR: 0.63; 95% CI: 0.42–0.93; P = .02), the NICU (RR: 0.62; 95% CI: 0.39–0.98; P = .04), and the Pediatric Bone Marrow Transplant Unit (RR: 0.52; 95% CI: 0.29–0.91, P = .02). CONCLUSIONS: Universal gloving during RSV season was associated with significantly lower rates of bacteremia and central line–associated bloodstream infections, particularly in the ICUs and the Pediatric Bone Marrow Transplant Unit.

Risk factors for surgical site infections after pediatric spine operations.

Study Design. Matched case-control study. Objective. To identify modifiable risk factors for surgical site infections (SSIs) after pediatric spinal fusion. Summary of Background Data. The number of SSIs after pediatric spinal fusions increased. Methods. Between July 2001 and July 2010, 22 of 598 pediatric patients who underwent spinal fusion at a university hospital acquired SSIs. Each patient with an SSI was matched with 2 controls by procedure date. Bivariable and multivariable analyses were used to identify risk factors for SSIs and outcomes of SSIs. Results. Gram-negative organisms caused more than 50% of the SSIs. By multivariable analysis, neuromuscular scoliosis (odds ratio [OR] = 20.8; 95% confidence interval [CI], 3.1–889.5; P < 0.0001) and weight-for-age at the 95th percentile or higher (OR = 8.6; 95% CI, 1.2–124.9; P = 0.02) were preoperative factors associated with SSIs. Blood loss (OR = 1.0; 95% CI, 1.0–1.0; P = 0.039) and allografts and allografts in combination with other grafts were operative risk factors for SSIs. The final overall risk model for SSIs was weight-for-age at the 95th percentile or higher (OR = 4.0; 95% CI, 1.4–∞; P = 0.037), American Society of Anesthesiologists score 3 or more (OR = 3.8; 95% CI, 1.6–∞; P = 0.01), and prolonged operation duration (OR = 1.0/min increase; 95% CI, 1.0–1.0; P = 0.004). SSIs were associated with 2.8 days of additional postoperative length of stay (P = 0.02). Neuromuscular scoliosis was the only factor significantly associated with hospital readmission (OR = 23.6; 95% CI, 3.8–147.3; P = 0.0007). Conclusion. Our results suggest that pediatric patients undergoing spinal fusion might benefit from antimicrobial prophylaxis that covers gram-negative organisms. Surgical duration, graft implantation, and blood loss are potentially modifiable operative risk factors. Neuromuscular scoliosis, high weight-for-age, and American Society of Anesthesiologists scores 3 or more may help surgical teams identify patients at high risk for SSI. Level of Evidence: 4

Molecular Epidemiology of Methicillin–Resistant Staphylococcus Aureus in a Veterans Administration Medical Center

OBJECTIVES To determine whether patients who were colonized or infected with methicillin-resistant Staphylococcus aureus (MRSA) persistently carried the same strain and to identify the extent of strain variation within a population of patients. DESIGN Molecular typing by pulsed-field gel electrophoresis (PFGE) of stored MRSA isolates. SETTING A Veterans Administration Medical Center with 288 hospital, 45 intermediate-care, and 75 extended-care beds. ISOILATES: Between January 1991 and March 1993, 91 patients had MRSA identified in routine cultures. One hundred isolates from 57 patients (63%) were available for typing. RESULTS Before 1988, only occasional MRSA isolates were identified. By 1993, 50% of S. aureus isolates from unique patients were resistant to methicillin. PFGE identified 7 MRSA strains, 3 of which were identified in specimens from 1 patient each. The most common strains were SD4 (20 patients), SD1 (12 patients), SD2 (12 patients), and SD5a (5 patients). Twenty patients had 2 or more isolates obtained at least 1 week apart (mean, 30.7 weeks; range, 1 to 102 weeks). Of these patients, 12 were colonized or infected with only one strain (mean time observed, 25.1 weeks; range, 1 to 82 weeks). Eight patients had at least 2 different strains (mean time observed, 39 weeks; range, 2 to 102 weeks). CONCLUSION Numerous MRSA strains circulated in this endemic setting, 40% of patients observed over time were colonized or infected with more than one strain. Molecular typing was an essential tool for evaluating the epidemiology of MRSA in this setting.

Surgical site infections and cellulitis after abdominal hysterectomy

OBJECTIVES To identify risk factors for and outcomes of surgical site infections and cellulitis after abdominal hysterectomies. STUDY DESIGN We used logistic regression analysis to analyze data from a case-control study of 1104 patients undergoing abdominal hysterectomies at a university hospital between Jan. 1, 2007 and Dec. 30, 2010. RESULTS Factors significantly associated with surgical site infections and with cellulitis were: pulmonary disease, operations done in Main Operating Room East, and seroma. Body mass index >35, no private insurance, and fluid and electrolyte disorders were risk factors for surgical site infections. The mean prophylactic dose of cefazolin was significantly higher for controls than for patients with surgical site infections. Preoperative showers with Hibiclens (Molnlycke Health Care US, LLC, Norcross, GA) and cefazolin prophylaxis were associated with a significantly decreased cellulitis risk. Surgical site infections and cellulitis were significantly associated with readmissions and return visits and surgical site infections were associated with reoperations. CONCLUSION Preoperative showers, antimicrobial prophylaxis, surgical techniques preventing seromas, and the operating room environment may affect the risk of surgical site infections and cellulitis after abdominal hysterectomies.

The numbers game: Sample-size determination

Sample-size determination is a crucial component of study design. Estimates of sample size are influenced by the amount of change that must occur between study groups and the degree of risk that the investigator is willing to accept in evaluating the null hypothesis. A complete understanding of the impact of sample size on the interpretation of study data is therefore a prerequisite for quality, innovative, valid research.

Preventing Falls in the Elderly

PURPOSE: The objective of this study 1 was to assess the effects of interventions designed to reduce the incidence of falls in elderly people who live in the community or who are cared for in hospitals or in institutions such as longterm care facilities (LTCFs). BACKGROUND: About one-third of elderly persons living in the community fall each year. For many elderly persons, falls and their associated injuries cause significant disability, loss of independence, or death. Falls are the single largest category of reported incidents in hospitals. 2–4 About 36,000 patients in the United States, many of whom are elderly, suffer significant adverse events from nosocomial falls each year, 4 and patients who fall are hospitalized 12 days longer and have higher charges than do controls. 5 Falls are the most commonly reported incident in LTCFs 6 and are a frequent reason for transferring residents from LTCFs facilities to acute care hospitals. 7 Numerous investigators have studied risk factors for falls and possible interventions to prevent falls and fallassociated injuries. The methods for many studies were less than optimal, and the results of different studies often conflict. This may be due to several factors, including differences in methods and patient populations and the multifactorial nature of risks for falls. This Cochrane review 1 attempts to find common threads among diverse intervention trials so that health professionals can use data to inform their practices regarding falls. DATA SOURCES: The reviewers contacted researchers, read reference lists from articles, and searched the following databases to identify randomized trials of interventions to minimize the effect of or exposure to risk factors for falling in elderly persons: MEDLINE (1966–2001), EMBASE (1988–2001 week 14), CINAHL (1982–March 2001), PsycLIT, Social Science Citation Index (to May 1997), the National Research Register (Issue 1, 2001) Current Controlled Trials (www.controlled-trials.com Accessed May 25, 2001), the Cochrane Musculoskeletal Group specialized register (January 2001), the Cochrane Controlled Trials Register (the Cochrane Library, Issue 1, 2001). The last search was done in March 2001. STUDY SELECTION CRITERIA: Two reviewers independently reviewed the data sources to identify relevant trials. Two reviewers evaluated the full text of these reports and selected those reporting results of appropriate randomized trials done in the community, hospitals, or LTCFs. The primary outcomes of interest were the number of persons who fell, the number of falls, the number of persons sustaining injuries from falls, and the severity of falls. The reviewers excluded nonrandomized trials (n 34) and trials that focused on intermediate outcomes or that did not report outcomes of falls (n 26). DATA EXTRACTION: Two reviewers, who were not blinded to the authors of the manuscript, independently assessed the methodological quality. Reviewers who participated in clinical trials did not assess the quality of the studies in which they were involved. Disagreements were resolved by consensus or by third-party adjudication. Data from individually randomized studies were analyzed using MetaView in Review Manager (RevMan 2000, The Cochrane Collaboration, Oxford, England). Data from studies randomized as clusters were excluded. The fixedeffects model was used to calculate the individual and pooled statistics for dichotomous data. Results were reported as relative risks (RRs) with 95% confidence intervals (CIs). Pooled weighted mean differences with 95% CIs were calculated for continuous data. Heterogeneity between pooled trials was tested using a standard chi-squared test and was considered to be significant when P .1. MAIN RESULTS: The review assessed 40 trials that had a median quality score of 0.66 (range 0.39–0.88).

Screening Patients Undergoing Total Hip or Knee Arthroplasty with Perioperative Urinalysis and the Effect of a Practice Change on Antimicrobial Use.

OBJECTIVE To identify predictors of treatment for urinary tract infections (UTI) among patients undergoing total hip (THA) or knee (TKA) arthroplasties and to assess an intervention based on these predictors. DESIGN We conducted a retrospective cohort study of 200 consecutive patients undergoing THA/TKA between February 21, 2011, and June 30, 2011, to identify predictors of treatment for UTI and a prospective cohort study of 50 patients undergoing these procedures between May 21, 2012, and July 17, 2012, to assess the association of signs or symptoms and UTI treatment. We then conducted a before-and-after study to assess whether implementing an intervention affected the frequency of treatment for UTI before or after THA/TKA. SETTING The orthopedics department of a university health center. PATIENTS Patients undergoing THA or TKA. INTERVENTION Surgeons revised their UTI screening and treatment practices. RESULTS Positive leukocyte esterase (P5 (P=.01; P=.01) were associated with preoperative or postoperative UTI treatment. In the prospective study, 12 patients (24%) had signs and symptoms consistent with UTI. The number of patients treated for presumed UTI decreased 80.2% after the surgeons changed their practices, and surgical site infection (SSI) rates, including prosthetic joint infections (PJIs), did not increase. CONCLUSIONS Urine leukocyte esterase and white blood cell count were the strongest predictors of treatment for UTI before or after THA/TKA. The intervention was associated with a significant decrease in treatment for UTI, and SSI/PJI rates did not increase. Infect Control Hosp Epidemiol 2017;38:281-286.