Paul B. L'Ecuyer

Results of a comprehensive infection control program for reducing surgical-site infections in coronary artery bypass surgery.

OBJECTIVE To evaluate the efficacy of a comprehensive infection control program on the reduction of surgical-site infections (SSIs) following coronary artery bypass graft (CABG) surgery. DESIGN Prospective cohort study. SETTING 1,000-bed tertiary-care hospital. PATIENTS Persons undergoing CABG with or without concomitant valve surgery from April 1991 through December 1994. INTERVENTIONS Prospective surveillance, quarterly reporting of SSI rates, chlorhexidene showers, discontinuation of shaving, administration of antibiotic prophylaxis in the holding area, elimination of ice baths for cooling of cardioplegia solution, limitation of operating room traffic, minimization of flash sterilization, and elimination of postoperative tap-water wound bathing for 96 hours. Logistic regression models were fitted to assess infection rates over time, adjusting for severity of illness, surgeon, patient characteristics, and type of surgery. RESULTS 2,231 procedures were performed. A reduction in infection rates was noted at all sites. The rate of deep chest infections decreased from 2.6% in 1991 to 1.6% in 1994. Over the same period, the rate of leg infections decreased from 6.8% to 2.7%, and of all SSI from 12.4% to 8.9%. The adjusted odds ratio (OR) for all SSIs for the end of 1994 compared to December 31, 1991, was 0.37 (95% confidence interval [CI95], 0.22-0.63). For deep chest and mediastinal infections, the adjusted OR comparing the same period was 0.69 (CI95, 0.28-1.71). CONCLUSIONS We observed significant reductions in SSI rates of deep and superficial sites in CABG surgery following implementation of a comprehensive infection control program. These differences remained significant when adjusted for potential confounding covariables.

Randomized prospective study of the impact of three needleless intravenous systems on needlestick injury rates.

OBJECTIVE To determine the impact of three needleless intravenous systems on needlestick injury rates. DESIGN Randomized controlled trial. SETTING 1,000-bed tertiary-care Midwestern hospital. PARTICIPANTS Nursing personnel from general medical, general surgical, and intensive-care units. INTERVENTIONS From June 1992 through March 1994, a metal blunt cannula (MBC), two-way valve (2-way), and plastic blunt cannula (PBC) were introduced into three study areas, and needlestick injury rates were compared to three control areas using traditional needled devices. RESULTS 24 and 29 needlestick injuries were reported in study and control areas. Intravenous-therapy-related injuries comprised 45.8% and 57.1% of injuries in each area. Thirty-seven percent and 20.7% of study and control area needlestick injuries were considered to pose a high risk of bloodborne infection. The 2-way group had similar rates of total and intravenous-related needlestick injuries compared to control groups. The PBC group had lower rates of total and intravenous-related needlestick injuries per 1,000 patient-days (rate ratios [RR], 0.32 and 0.24; 95% confidence intervals [CI95], 0.12-0.81 and 0.09-0.61; P = .02 and P = .003, respectively) and per 1,000 productive hours worked (RR, 0.11 and 0.08; CI95, 0.01-0.92 and 0.01-0.69; P = .03 and P = .005, respectively) compared to controls. CONCLUSIONS Needlestick injuries continued in study areas despite the introduction of needleless devices, and risks of bloodborne pathogen transmission were similar to control areas. The PBC device group noted lower rates of needlestick injuries compared to controls, but there were problems with product acceptance, correct product use, and continued traditional device use in study areas. Low needlestick injury rates make interpretations difficult. Further studies of safety devices are needed and should attempt greater control of worker behavior to aid interpretation.

Varied approaches to tuberculosis control in a multihospital system.

OBJECTIVES To document the actual tuberculosis (TB) control policies and procedures in a nonoutbreak setting in a variety of hospitals. To determine if any particular practices are linked to higher rates of employee tuberculin skin-test conversion. DESIGN Survey of hospital occupational health and infection control practitioners for the year 1994 regarding hospital TB policies. Review of hospital records to verify the number of patients with TB at each hospital and to verify the number of employees with positive tuberculin skin tests. Smoke-stick testing of negative-pressure ventilation rooms. SETTING A 13-hospital health system in the Midwest. RESULTS Hospitals ranged in size from 40 to 1,208 beds (median 220) and employed 150 to 6,500 workers (median 875). There were seven rural and six urban centers, including four teaching hospitals. All 13 hospitals had TB control plans, and all performed annual tuberculin skin testing on employees. Annual skin-test positivity rates ranged from 0% to 1.0% (median 0.3%). Negative-pressure ventilation rooms were available in 11 hospitals. The percentage of negative-pressure rooms with effective negative pressure ranged from 44% to 100% (median 95%). Three of the 13 hospitals used high-efficiency particulate air (HEPA) masks as primary personal respiratory protection, and 8 used dust-mist or dust-mist-fume masks. We found no relation between the type of face mask used, number of functional negative-pressure rooms, or hospital TB risk category, and employee skin-test conversion rates. CONCLUSIONS Considerable variation existed in the TB control policies and procedures between hospitals, but employee TB skin-test conversion rates were low in all settings.

Results of a comprehensive infection control program for reducing surgical-site infections in coronary artery bypass surgery: further data from the authors.

We welcome Dr. Lee’s contribution to the discussion of the issues raised in our article1 and value his demonstrated perspicacity and clarity. The leg wounds of the patients in our study were closed by subcuticular closure with Dexon suture in the majority of cases during the study years. When time constraints dictated, or in particularly obese patients, there was a preference for skin staples. There was no systematic change in surgical techniques with regard to leg-wound closure during the study. It is, however, likely that greater attention was paid to issues such as wound irrigation and wound drainage during the study, as individual surgical assistants responsible for wound closure were receiving feedback regarding their specific surgical-site infection rates. To detect possible surgical-site infections, we used a prospective cardiothoracic (CT) surgery database and an infection control (IC) database. A coordinator reviewed all cases and all outcomes. The coordinators and IC staff remained the same throughout the study period. IC staff made rounds on the ward and the intensive care unit 2 or 3 times per week. The CT nurses and medical staff called the IC department for every suspicious wound. IC staff reviewed the hospital chart and diagnosis of suspected cases. We monitored antibiotic use, as well as microbiology culture results. The practice of all cardiac surgeons at Barnes Hospital is to see patients 1 month postoperatively, and greater than 90% are seen here at least once in followup. Infection control nurses at other hospitals call us if they identify an infection thought to be due to an operation in Barnes Hospital. The primary outcome in this study was total surgicalsite infections. This decreased significantly. We also looked at two subgroups: deep chest infections, as defined in our article, and combined deep and superficial incisional leg infections, referred to in the article as “leg infections.” Most of the improvement in infection rates occurred in leg infections (Table 1). We did not show a statistically significant decrease in deep chest infections; however, our sample size is too small for the study to have the power to detect a clinically important change in this outcome. Superficial incisional chest infection rates increased for the first 3 years and decreased to a rate above the initial rate in the last year of the study. Our term deep chest infections is not standard terminology, but it is unambiguously defined in the “Methods” section of the article in terms of the Centers for Disease Control and Prevention categories outlined by Dr. Lee. It includes mediastinal and sternal infections, but excludes cutaneous and subcutaneous infections of the sternal incision. We have one reservation about the validity of the analysis and have addressed this as described below. In general, any regression model assumes that the outcome of interest for a particular individual is independent of all other individuals in the study sample. Based on this assumption, one calculates the errors of the estimates, and thus one generates a probability value for hypothesis testing. However, in a situation like the one in our study, the independence of the events cannot be taken for granted. Is it possible that when one individual gets a surgical-site infection others are at higher risk? This certainly would be biologically plausible. Events that occur over a period of time often have a tendency toward related outcomes for events that are in close temporal proximity. This is timeseries auto-correlation. If it were present in a series of cases such as we present, it would invalidate the hypothesis testing in the logistic regression model. We have tested for the presence of auto-correlation in the residual values for the models described in the article. In this case, none was found. However, it is possible that the model could be sensitive to small degrees of auto-correlation that were not statistically significant.

Management and outcome of tuberculosis in two St Louis Hospitals, 1988 to 1994

OBJECTIVE To describe management and outcome of tuberculosis (TB) and current practices for isolation in two urban hospitals in the Midwest. DESIGN Retrospective cohort study. SETTING Barnes Hospital and Jewish Hospital, tertiary-care and community hospitals affiliated with Washington University School of Medicine in St Louis, Missouri. PATIENTS All adult patients with a positive culture for Mycobacterium tuberculosis from 1988 to 1994. RESULTS We identified 122 cases at Barnes and Jewish Hospitals (36.5/100,000 hospital discharges), median age was 59.0 years, 61.5% were non-Caucasian, and 54.9% resided within the city limits. Underlying risk conditions were common: substance abuse (25%), recent TB contact (24%), and foreign birth (13%). Coexistent human immunodeficiency virus infection (8%) was uncommon. Of skin-tested cases, 22% were anergic; of the rest, 22% tested negative. Almost 20% of cases had prior positive skin tests, and thus were preventable, but had not received adequate prophylaxis. Of hospitalized patients with pulmonary TB, 70% received respiratory isolation. Antibiotic resistance was recognized in 16%; only 19% of cases initially received four-drug therapy. TB-related death occurred in 16%. CONCLUSIONS In this area, TB cases primarily involve traditional risk groups without HIV coinfection. Current infection control practices, diagnostic strategies, and initial treatment regimens are suboptimal. Education about local disease epidemiology is needed to prevent nosocomial TB transmission.

Tuberculosis, hepatitis B, rubella, rubeola, and varicella infection and immunity among medical school employees.

OBJECTIVE To assess baseline health status of a medical school employee population and to assess this populations acceptance of vaccination and other interventions to reduce risk of disease transmission. DESIGN A retrospective review of an employee health records database for a 4-year period. SETTING A large, urban university hospital. PARTICIPANTS 5,007 employees screened by employee health for immunity to vaccine-preventable illnesses and tuberculosis. RESULTS 9.4% of the employees had positive tuberculin skin tests, with a conversion rate of 6.4% for those who had negative tests within the previous 2 years. Two individuals were identified who had active pulmonary tuberculosis. Fewer than 10% of the individuals for whom isoniazid chemoprophylaxis was recommended completed the 6 months of therapy. Most clinical employees (96.1%) did not have a history of prior hepatitis B virus (HBV) infection or immunization, but 77% of them subsequently completed the vaccination series. Most employees with a negative history for infection with or immunization against rubella, rubeola, and varicella had serological evidence of immunity (90.2%, 97.9%, and 87.2%, respectively). CONCLUSIONS Review of aggregate employee health databases may assist individuals who must establish strategies for prevention of occupational illness and disease transmission in this specialized setting. While many employees at risk for HBV complete the vaccination series, strategies for improving this rate could be helpful. Substantial work is needed to analyze reasons why so few individuals for whom isoniazid chemoprophylaxis is recommended complete the therapy, and strategies tailored to the impediments identified should be implemented.