CDC definitions of nosocomial surgical site infections, 1992: a modification of CDC definitions of surgical wound infections

Decision support for infectious diseases--a working prototype

This paper presents a decision support system for nosocomial infections and its integration in the large HIS of the University Hospital of Giessen. The system comprises five different engines and a data dictionary. It is designed to detect hospital acquired infections even in a situation where only a restricted amount of clinical data is available (the data is split up in different information systems). Furthermore the model prevents time consuming manual data entry. The five engines split the main task into: (1) a preselection, which sorts out patients who definitely do not have a nosocomial infection; (2) a rule based reasoning process which detects patients likely to have such an infection; (3) an alarm process which is responsible for the presentation of the alert; (4) an explanation process to follow up the reasoning; and (5) statistic tools to answer specific hygienic questions. A data dictionary supplies the controlled vocabulary, which is required to understand data structures used in the different clinical subsystems and may those with each other.

The effect of surgical site infections on outcomes and resource utilization after liver transplantation

BACKGROUND

Although postoperative infections have a significant impact on morbidity and mortality after orthotopic liver transplantation (OLT), less is known about their economic implications. In this study, we sought to identify risk factors and estimate the impact of surgical site infections on 1-year mortality, graft survival, and resource utilization after OLT.

METHODS

We studied 777 first, single-organ liver transplant recipients from the National Institute of Diabetes and Digestive and Kidney Diseases Liver Transplantation Database. Surgical site infections (n = 292, 37.8%) were defined as bacterial or fungal infections of the liver, intestine, biliary tract, surgical wound, or peritoneum within 1 year of transplantation. A subset of these (n = 159) occurred during the transplant hospitalization and were used to estimate excess charges associated with surgical site infections.

RESULTS

Leaks in the choledochojejunostomy (odds ratio [OR] = 7.1, P =.001) and choledochocholedochostomy (OR = 2.5, P =.002), extended operation duration in hours (OR = 1.2, P =.002), serum albumin levels in grams per liters (OR = 0.71, P =.009), ascites (OR = 1.43, P =.037), and administration of OKT3 within 7 days (OR = 1.49, P =.039) significantly increased risk of infection. Surgical site infections did not significantly increase 1-year mortality (88.5% vs 91.5%, P =.19) but significantly increased 1-year graft loss (79.8% vs 86.5%, P =.022). Patients with surgical site infections incurred approximately 24 extra hospital days and $159,967 in excess charges (P =.0001). Multivariate analysis reduced the estimate of excess charges to $131,276 (P =.0001).

CONCLUSIONS

Liver transplant recipients who develop surgical site infection have significantly higher resource utilization requirements than those who do not. These results imply substantial returns to preventative efforts directed at surgical site infections in patients undergoing OLT.

A retrospective review of 228 episodes of infective endocarditis where rheumatic valvular disease is still common

Two hundred and twenty-eight episodes of infective endocarditis in adult patients (mean age 36 years) were reviewed retrospectively. There were 183 episodes (80%) of native valve, 15 (7%) early prosthetic valve and 30 (13%) late prosthetic valve endocarditis. The most common predisposing factor was rheumatic valvular disease (65%). None of the patients were intravenous drug users. According to the Duke criteria, the number of definite, probable and rejected episodes were 121 (53%), 94 (41%) and 13 (6%), respectively. Additional minor criteria increased the number of definite endocarditis to 82%. The Duke criteria are not primarily intended to influence treatment decisions but are helpful in standardising research activities. The choice of the level of sensitivity or specificity of the criteria may be adjusted according to the aim of the study and prevalence of disease in a particular area. More sensitive criteria may be valuable in those countries where the prevalence of rheumatic valvular disease is still high.

Surgical site infections in ambulatory surgery: a 5-year experience

OBJECTIVES

To evaluate the ambulatory surgical site infection rate and risk factors associated with surgical site infection.

METHODS

We conducted a case-control analysis of all ambulatory surgeries between January 1, 1993, and December 31, 1997. The frequency of surgical site infection per 100 surgeries was calculated. The odds ratio (OR) was estimated by using logistic regression analysis.

SETTING

A 140-bed tertiary-care teaching hospital for adult patients with cancer.

RESULTS

The study followed 1350 outpatient surgeries. Thirty-eight patients had a surgical site infection (rate per 100 surgeries: 2.8). The risk factors statistically associated with surgical site infection were postoperative antibiotics (OR = 7.5; 95% CI, 2.5-23.0), and surgical time >35 minutes (OR = 2.4; 95% CI, 1.1-5.5).

CONCLUSIONS

The surgical site infection rate for same-day surgery at our hospital is within the limits reported in the literature and below the rates reported previously for inpatient surgeries at our hospital. Full review of medical records and microbiology reports at day 30 allowed us to identify infections that otherwise would have been missed. Postoperative antibiotics may increase the risk of infection.

Impact of antibiotic prophylaxis on wound infection after cesarean section in a situation of expected higher risk

BACKGROUND

To measure rates of incisional surgical site infection (ISSI) after cesarean section (CS) and to assess risks for infection.

METHODS

Prospective surveillance for ISSI at a 540-bed hospital in Saudi Arabia by using Centers for Disease Control and Prevention definitions for infection and the National Nosocomial Infections Surveillance (NNIS) system risk index.

RESULTS

Seven hundred thirty-five CSs were studied from September 1998 to July 1999; 72% were emergency procedures, despite a 95% rate of antenatal care. The overall ISSI rate was 2.8% (95% confidence interval [CI], 1.7%-4.3%). The rate for NNIS risk category 0 was 2.4% (95% CI, 1.3%-4.2%; n = 536) and for category 1 was 4.1% (95% CI, 1.8%-8.6%; n = 170). In the multivariate analysis, the only independent risks for ISSI were duration of surgery (OR = 1.01; 95% CI, 1.00-1.03; P =.02) and no antibiotic prophylaxis (OR = 3.09; 95% CI, 1.10-9.11; P =.04). Antibiotic prophylaxis was inconsistently administered among both emergency and elective CS. Infection control procedures were inadequate in the obstetric suite operating room.

CONCLUSIONS

Despite deficient infection control practices in the setting described, ISSI rates after CS were judged "acceptable" compared with NNIS benchmark rates. This was attributed to prescribing antibiotic prophylaxis for patients at low risk as well as high risk of infection.

Epidemiology of and surveillance for postpartum infections

We screened automated ambulatory medical records, hospital and emergency room claims, and pharmacy records of 2,826 health maintenance organization (HMO) members who gave birth over a 30-month period. Full-text ambulatory records were reviewed for the 30-day postpartum period to confirm infection status for a weighted sample of cases. The overall postpartum infection rate was 6.0%, with rates of 7.4% following cesarean section and 5.5% following vaginal delivery. Rehospitalization; cesarean delivery; antistaphylococcal antibiotics; diagnosis codes for mastitis, endometritis, and wound infection; and ambulatory blood or wound cultures were important predictors of infection. Use of automated information routinely collected by HMOs and insurers allows efficient identification of postpartum infections not detected by conventional surveillance.

Multicenter surveillance study for nosocomial infections in major hospitals in Korea. Nosocomial Infection Surveillance Committee of the Korean Society for Nosocomial Infection Control

BACKGROUND

The goals of a surveillance for nosocomial infections (NIs) are to observe the magnitude and characteristics of NIs and to plan and evaluate policies and guidelines of infection control. This study was designed to determine the rate and distribution of NIs and their causative pathogens in Korean hospitals.

METHODS

Prospective surveillance was performed at 15 acute care hospitals with more than 500 beds during a 3-month period from June to August 1996. The case-finding methods were laboratory-based surveillance for patients in the general wards and a direct review of medical charts done regularly for all the patients in the intensive care units.

RESULTS

A total of 3162 NIs were found among 85,547 discharged patients, with an overall nosocomial infection rate of 3.70 per 100 patients discharged. Urinary tract infections constituted 30.3% of all NIs. Other infections were pneumonias, 17.2%, surgical site infections, 15.5%, and primary bloodstream infections, 14.5%. The infection rate was the highest in neurosurgery (14.21), followed by neurology (8. 62) and ontology services (6.70). The infection rate in intensive care units was higher than it was in the general wards (10.74 vs 2. 57, P =.001). The commonly isolated organisms were Staphylococcus aureus (17.2%), Pseudomonas aeruginosa (13.8%), and Escherichia coli (12.3%).

CONCLUSIONS

This first multicenter surveillance study provided extensive information on the current status and trends of NIs in major hospitals in Korea. The results may contribute to the evaluation of infection control programs and the development of effective strategies in these hospitals.

Wound closure technique and acute wound complications in gastric surgery for morbid obesity: a prospective randomized trial

BACKGROUND

During the past 10 years, numerous clinical studies have supported the use of continuous monofilament fascial closure after laparotomy. Because of the increased incidence of surgical-site infections and other acute wound complications in the morbidly obese, these patients are well suited for a study of technical factors that may affect the frequency of these wound complications.

STUDY DESIGN

A prospective, randomized study of the midline fascial closure technique in gastric bariatric operations was conducted between 1991 and 1998 in 331 consecutive morbidly obese patients. At the time of closure of the upper midline laparotomy wound, the patients were randomized into two groups: Group I patients (n = 172) underwent continuous fascial closure and group II patients (n = 159) underwent interrupted fascial closure. All patients received prophylactic antibiotics in a similar fashion. Wounds were monitored for 30 days postoperatively, and acute wound complications were classified as superficial or deep. Superficial complications included superficial surgical-site infections, seromas, and hematomas. In all superficial complications, the fascia remained uninvolved and intact. Deep wound complications included deep surgical-site infections and fascial dehiscence.

RESULTS

A total of 49 acute wound complications occurred (15%). There were 22 superficial (7%) and 27 deep (8%) wound complications in the 331 in the patients studied. Group I patients experienced fewer total wound complications than group II patients (18 versus 31; p=0.021). Group I patients also experienced fewer deep wound complications than group II (5 versus 22; p = 0.003).

CONCLUSIONS

Continuous fascial closure reduces major acute wound complications in morbidly obese patients undergoing gastric operations for obesity.

Surgical site infections at the National Cancer Institute in Mexico: a case-control study

OBJECTIVES

To quantify the surgical infection rate and to identify risk factors associated with surgical site infection.

METHODS

We conducted a case-control study of all surgical patients between January 1, 1993, and June 30, 1994. The frequency of surgical site infection per 100 surgeries was calculated. The odds ratio (OR) was estimated by using logistic regression analysis.

SETTING

A 130-bed tertiary-care teaching hospital for adult patients with cancer.

RESULTS

The study followed 3372 surgeries. Three hundred thirteen patients had a surgical site infection (rate per 100 surgeries: 9. 30). The risk factors associated with surgical site infection were diabetes mellitus (OR = 2.5, 95% confidence interval [CI] = 1.27-4. 91), obesity (OR = 1.76, 95% CI = 1.14-2.7), presence of surgical drains for >5 and <16 days (OR = 1.84, 95% CI = 1.02-3.31), and presence of surgical drains for >/=16 days (OR = 2.14, 95% CI = 1. 0-4.6). The bacteria most frequently isolated were Escherichia coli 38 (21.8% of the total of microorganisms found), Pseudomonas sp 22 (12.6%), Staphylococcus aureus 16 (9.2%), and coagulase-negative Staphylococcus 25 (13.6%). The coexistence of other nosocomial infections was greater among the cases (OR = 1.8, 95% CI = 1.1-3.1) than in the control group.

CONCLUSIONS

The surgical site infection rate in our hospital is slightly higher than the rates reported for general hospitals. The risk factors associated with surgical site infection are similar to those previously reported. Diabetes mellitus, obesity, and prolonged presence of a surgical drain increased the risk of infection.

Quantifying excess length of postoperative stay attributable to infections: a comparison of methods

To quantify the net effect of deep surgical site infection (DSSI) on postoperative stay (POS) among patients who had undergone open heart surgery, and to assess the comparability of two methods, two observational studies were conducted: one on a retrospective cohort of 701 operated patients, and the other on a cohort of 31 infected patients versus a cohort of uninfected patients, with 1:1 matching. In addition to DSSI, a further three factors were identified by multivariate analysis as independent POS-related predictor variables. After internal validation of the multivariate model, excess POS attributable to DSSI amounted to 20.7 days (95% confidence interval [CI] 16.7-24.9). In contrast, excess length of stay attributable to DSSI among the matched pairs who survived infection (22) totaled 14.3 days (95% CI 3.2-25.4) and 26.5 days (mean and median differences). Multivariate techniques may prove a more appropriate and reliable analysis than matched-pair comparisons for the purpose of evaluating the extra stay and cost attributable to the nosocomial infections.

Prevalence of nosocomial infections in Spain: EPINE study 1990-1997. EPINE Working Group

From 1990, a study on the prevalence of nosocomial infections has been carried out yearly in Spanish hospitals. Acute care hospitals with more than 50 beds were involved on a voluntary basis. In 1990, 123 hospitals participated and by 1997 the number of hospitals had reached 214. The objective of the study is to examine the situation in each hospital, and to collect data across the country, by means of a common protocol. The overall prevalence of nosocomial infections has significantly decreased in Spain. The prevalence of infected patients has been about 7% in the three last studies. The prevalences for urinary tract infections and surgical wound infections have decreased, while prevalences for lower respiratory tract infections and bacteraemia have increased. Urinary tract infections have occupied the first position over the eight surveys. Second place was taken by surgical wound infections from 1990 to 1995, and by lower respiratory tract infections in 1996-1997. With the exception of Intensive Care Units, the prevalence of nosocomial infections has been decreasing in all hospital areas. The mean age of hospitalized patients has increased, so has the proportion of patients with one or more intrinsic risk factors and the proportion of those with one or more instrumentations. The proportions of patients with a short or a very long hospital stay have increased, revealing a change that no doubt reduces nosocomial infection rates. The use of antimicrobial drugs has shown a significant increase, from 33.8% of patients in 1990 to 35.8% in 1997.

Nosocomial bacterial meningitis, including central nervous system shunt infections

Nosocomial bacterial meningitis and CSF shunt infections result in considerable morbidity and mortality, necessitating an organized and thoughtful approach to prevention, diagnosis, and management. Prophylactic antibiotics appear to reduce the rate of postcraniotomy meningitis often caused by S. aureus. On the other hand, prophylactic antibiotics do not appear to reduce the risk of developing a CSF shunt infection. CSF shunt infections usually require shunt removal and antimicrobial chemotherapy to effect a successful outcome.

Guideline for Prevention of Surgical Site Infection, 1999. Centers for Disease Control and Prevention (CDC) Hospital Infection Control Practices Advisory Committee

EXECUTIVE SUMMARY The "Guideline for Prevention of Surgical Site Infection, 1999" presents the Centers for Disease Control and Prevention (CDC)'s recommendations for the prevention of surgical site infections (SSIs), formerly called surgical wound infections. This two-part guideline updates and replaces previous guidelines.1,2 Part I, "Surgical Site Infection: An Overview," describes the epidemiology, definitions, microbiology, pathogenesis, and surveillance of SSIs. Included is a detailed discussion of the pre-, intra-, and postoperative issues relevant to SSI genesis. Part II, "Recommendations for Prevention of Surgical Site Infection," represents the consensus of the Hospital Infection Control Practices Advisory Committee (HICPAC) regarding strategies for the prevention of SSIs.3 Whenever possible, the recommendations in Part II are based on data from well-designed scientific studies. However, there are a limited number of studies that clearly validate risk factors and prevention measures for SSI. By necessity, available studies have often been conducted in narrowly defined patient populations or for specific kinds of operations, making generalization of their findings to all specialties and types of operations potentially problematic. This is especially true regarding the implementation of SSI prevention measures. Finally, some of the infection control practices routinely used by surgical teams cannot be rigorously studied for ethical or logistical reasons (e.g., wearing vs not wearing gloves). Thus, some of the recommendations in Part II are based on a strong theoretical rationale and suggestive evidence in the absence of confirmatory scientific knowledge.It has been estimated that approximately 75% of all operations in the United States will be performed in "ambulatory," "same-day," or "outpatient" operating rooms by the turn of the century.4 In recommending various SSI prevention methods, this document makes no distinction between surgical care delivered in such settings and that provided in conventional inpatient operating rooms. This document is primarily intended for use by surgeons, operating room nurses, postoperative inpatient and clinic nurses, infection control professionals, anesthesiologists, healthcare epidemiologists, and other personnel directly responsible for the prevention of nosocomial infections. This document does not: Specifically address issues unique to burns, trauma, transplant procedures, or transmission of bloodborne pathogens from healthcare worker to patient, nor does it specifically address details of SSI prevention in pediatric surgical practice. It has been recently shown in a multicenter study of pediatric surgical patients that characteristics related to the operations are more important than those related to the physiologic status of the patients.5 In general, all SSI prevention measures effective in adult surgical care are indicated in pediatric surgical care. Specifically address procedures performed outside of the operating room (e.g., endoscopic procedures), nor does it provide guidance for infection prevention for invasive procedures such as cardiac catheterization or interventional radiology. Nonetheless, it is likely that many SSI prevention strategies also could be applied or adapted to reduce infectious complications associated with these procedures. Specifically recommend SSI prevention methods unique to minimally invasive operations (i.e., laparoscopic surgery). Available SSI surveillance data indicate that laparoscopic operations generally have a lower or comparable SSI risk when contrasted to open operations.6-11 SSI prevention measures applicable in open operations (e.g., open cholecystectomy) are indicated for their laparoscopic counterparts (e.g., laparoscopic cholecystectomy). Recommend specific antiseptic agents for patient preoperative skin preparations or for healthcare worker hand/forearm antisepsis. Hospitals should choose from products recommended for these activitie

Nonshaved cranial neurosurgery

BACKGROUND

Preoperative shaving for cranial neurosurgical procedures is still recommended in textbooks. There are reports demonstrating the success of nonshaved surgery. The objective of this study was to compare the surgical infection rate of cranial neurosurgical procedures with two different scalp preparations: shaved or nonshaved.

METHODS

Clinical trials of nonshaved scalp preparation were performed in non-emergency cranial neurosurgical procedures at Songklanagarind Hospital from August 1994 to December 1996. Patients were entered in the nonshaved group using the following exclusion criteria: immunocompromised host, presence of infectious diseases, surgery with foreign material insertion, multiple operations within 1 month, and presence of traumatic wound around the operative site. Patients who survived less than 1 month after surgery were excluded except in cases where death resulted from intracranial infection.

RESULTS

During the 29-month period, 225 of 1,244 cranial neurosurgical procedures were selected for study. Ages ranged from 4 to 86 years. Brain tumors were encountered in 57%. In the nonshaved group, there were 89 procedures (80 cases), compared with 136 procedures (123 cases) in the shaved group. Surgical infection rates were 3.37% and 5.88%, respectively (p>0.05).

CONCLUSIONS

Nonshaved scalp preparation is recommended for nonemergency cranial neurosurgical procedures.

Nosocomial infection, indices of intrinsic infection risk, and in-hospital mortality in general surgery

The objectives of this paper are to assess whether two indices of intrinsic infection risk (the SENIC and the NNIS index) predict in-hospital mortality and the attributable in-hospital mortality due to nosocomial infection in surgical patients. A prospective study on 4714 patients admitted to three hospitals has been carried out. The relative risk and its 95% confidence interval (CI) were estimated. Multiple-risk factors adjusted for odds ratios (OR) were yielded by logistic regression analysis. Overall, 119 patients (2.5%) died before hospital discharge. Both the SENIC and the NNIS indices were related to in-hospital mortality in crude data. After controlling for several variables (age, sex, ASA score, cancer, renal failure, diabetes mellitus, stay at the ICU), the SENIC index did not show any significant trend with mortality (P = 0.252), whereas the trend was significant for the NNIS index (P < 0.001). Risk of death in patients with one nosocomial infection was 7.5%, and in patients developing more than one nosocomial infection was 17.1%. After adjusting for several confounding variables, the development of an organ/space surgical site infection was significantly related to mortality (OR = 4.5, 95% CI 1.5-15.6) as was blood infection (OR = 17.3, 95% CI 3.5-87.0). The association of a surgical site infection and either a respiratory tract infection or a blood infection also increased significantly the risk of in-hospital mortality (OR = 3.3, 95% CI 1.2-8.7). In conclusion, the NNIS index is a good predictor of in-hospital mortality. Patients developing an organ/space surgical site infection and/or a blood infection have an increased risk of in-hospital mortality.

Surgical wound infection surveillance: the importance of infections that develop after hospital discharge

BACKGROUND

The aim of this study was to evaluate two methods of post-discharge surgical wound surveillance and to compare the incidence and outcomes of wound infections that develop prior to patients' discharge with those that develop after hospital discharge.

METHODS

One thousand, three hundred and sixty inpatients who underwent major elective surgery in an 800-bed teaching hospital in western Sydney between February 1996 and July 1997 were followed prospectively. Pre-discharge wound surveillance was performed by clinical assessment by an independent researcher on the fifth (or later) postoperative day. Post-discharge wound surveillance was performed by a mail out of questionnaires completed independently by patients and surgeons.

RESULTS

Overall, 138 wound infections were diagnosed (incidence 10.1%), of which fewer than one-third (n = 44) were diagnosed before discharge (average 10.4 days postoperatively) and the remainder (n = 94) after discharge (average 20.6 days postoperatively). Seven hundred and eighty-two (57.5%) post-discharge survey forms were returned by patients and 680 (50.0%) by surgeons. When forms were returned by both surgeons and patients for the same wound (641 cases), there was substantial agreement in diagnosing infection or no infection (kappa = 0.73).

CONCLUSIONS

The majority of nosocomial surgical wound infections develop after the patients' discharge from hospital. A post-discharge surveillance programme including self-reporting of infections by patients and return of questionnaires by patients and surgeons is feasible in an Australian hospital setting. However, such a programme is labour and resource intensive and strategies to increase return of questionnaires are required.

Repeated multi-centre prevalence surveys of hospital-acquired infection in Greek hospitals. CICNet. Cretan Infection Control Network

Three prevalence studies for the estimation of hospital-acquired infections (HAIs) were carried out in eight Greek hospitals on an annual basis during the years 1994-1996. The overall prevalence of HAI was 6.8, 5.5 and 5.9% for the three years, respectively. Among these, urinary tract infections ranged from 22.4 to 38.2%, lower respiratory tract infections ranged from 21.1 to 32.6%, surgical site infections ranged from 14.6 to 22.7% and bloodstream infections ranged from 9.0 to 13.2%. The prevalence of antibiotic usage among the hospitalized patients was found to be 49.3% in 1994, 47.3% in 1995 and 52.7% in 1996. Unjustified prescription of prophylactic usage was found to be the major component of these high percentages. Appropriate use of antibiotics for prophylaxis is one of the priorities of the current infection control programmes. The development of a nationwide network for the surveillance of HAIs in Greece is planned using the experience gained.

Postoperative hospital-acquired infection in Hungvuong Obstetric and Gynaecological Hospital, Vietnam

A prospective study was conducted following 1364 major operations at the 450-bed Hungvuong Obstetric and Gynaecological Hospital in HoChiMinh City, Vietnam, from 1 May to 30 September 1997 to characterize postoperative hospital-acquired infections. These infections were identified by ward rounds, review of laboratory results and patient follow-up until 30 days after discharge. During the study period, 194 infections were identified, yielding a rate of 14.2 infections per 100 operations. The most common sites were surgical wound and urinary tract, contributing together 95.9% of all hospital-acquired infections. The four most common pathogens were Staphylococcus aureus (29.6%), Escherichia coli (20.4%), Enterococci (16.7%) and Staphylococcus epidermidis (14.8%).

Risk factors for surgical site infections diagnosed after hospital discharge

A prospective cohort study on 1103 consecutive patients undergoing general surgery with a follow-up of up to 30 days was undertaken to analyse the risk factors for surgical-site infection (SSI). Relative risks (RRs), crude and multiple-risk factors adjusted for by logistic regression analysis, and their 95% confidence intervals were calculated. One hundred and four patients (9.4%) developed infection, 81 in hospital and 23 at home. Predictors for in-hospital SSI differed from those for post-discharge SSI. In a crude analysis, an increased risk of post-discharge SSI occurred after clean-contaminated surgery (but not contaminated surgery). Stepwise logistic regression failed to identify any significant predictor for post-discharge SSI.

Applying the Centers for Disease Control and Prevention and National Nosocomial Surveillance system methods in Brazilian hospitals

BACKGROUND

Nosocomial infection is an important public health problem in Brazil. The better to understand and address this problem, we began using the National Nosocomial Infection Surveillance (NNIS) system in five Brazilian hospitals in 1991.

METHODS

Data were collected prospectively according to the NNIS protocol, by using nosocomial infection definitions from the Centers for Disease Control and Prevention.

RESULTS

From January 1991 to June 1995, the overall nosocomial infection rate was 5.1% or 9.7 nosocomial infections/1000 patient-days. From the detailed epidemiologic information obtained by using the NNIS methods, interventions were designed and implemented that have reduced specific nosocomial infection rates. For example, the incidence of infection caused by methicillin-resistant Staphylococcus aureus was reduced from 0.61 infections/1000 patient-days in 1991 to 0.05 infections/1000 patient-days in 1996 (p < 0.01). The surgical site infection rate after cesarean section was reduced from 11.6% in 1993 to 5.9% in 1996 (p < 0.05). Cost savings from a program to optimize the use of antimicrobial agents in one hospital was more than $1.8 million over a 45-month period.

CONCLUSION

The NNIS method was applicable in a wide variety of hospitals, even those with little or no experience with nosocomial infection surveillance. By using this method, we defined the detailed epidemiology of nosocomial infection and implemented interventions that have significantly reduced nosocomial infection rates while achieving substantial cost savings.

Incidence surveillance of wound infection in hernia surgery during hospitalization and after discharge in a university hospital

A six-month prospective incidence surveillance of wound infection was conducted in the department of general surgery of the Rio de Janeiro University Hospital. Postoperative infections were classified according to Centers for Disease Control criteria. This study reports a rate of 14.04% in surgical infections limited to herniorrhaphy and detected by surveillance. The majority (87.50%) of them were only apparent after hospital discharge. Fourteen out of 16 patients (88.60%) were not deemed to be at risk for surgical infections. Staphylococcus aureus was the most important pathogen associated with infection. This report shows that community surveillance is necessary to determine accurate rates of hospital-acquired infection and will help establish prevention and control policies in Brazil.

Definitions of key terms used in the NNIS System

For valid comparisons with the published NNIS nosocomial infection rates, hospitals must define data elements in the same way. Definitions for infections, risk factors, and populations monitored are specified in the NNIS System, but thus far only infection definitions and the list of NNIS operative procedure categories have been published. This article defines other key terms used in the NNIS System.

Should antibiotic prophylaxis be used routinely in clean surgical procedures: a tentative yes

BACKGROUND

The incidence of surgical site infection (SSI) after clean surgical procedure has traditionally been regarded as too low for routine antibiotic prophylaxis. But we now know that host factors may increase the risk of SSI to as high as 20%. We assessed the value of prophylactic cefotaxime in patients stratified for risk of SSI in a randomized double-blind trial.

METHODS

Patients admitted for clean elective operations were enrolled, stratified for risk by National Nosocomial Infection Survey criteria, and randomized to receive intravenous cefotaxime 2 gm or placebo on call for operation. They were followed for 4 to 6 weeks for SSI diagnosed by Centers for Disease Control and Prevention criteria.

RESULTS

Analysis of 775 patients showed that the 378 evaluable patients who received cefotaxime had 70% fewer SSI than those who did not--Mantel-Haenszel risk ratio (MH-RR) 0.31; 95% confidence intervals (CI) 0.11 to 0.83. Benefit was clear in the 616 low risk patients--0.97% versus 3.9% SSI (MH-RR 0.25, CI 0.07 to 0.87, p = 0.018), but only a trend was seen in 136 high risk patients--2.8% versus 6.1% SSI (MH-RR 0.48, CI 0.09 to 2.5).

CONCLUSIONS

The results indicate clear benefit for routine antibiotic prophylaxis in clean surgical procedures. High risk patients need more study.

An approach to the evaluation of quality indicators of the outcome of care in hospitalized patients, with a focus on nosocomial infection indicators. The Quality Indicator Study Group

The Quality Indicator Study Group was created by the governing boards of three national professional organizations that have interest and experience in epidemiology, nosocomial infection control and prevention, and quality of care improvement. The Study Group has reviewed the existing literature concerning quality indicators (QIs), interviewed experts in the field, and focused on how best to evaluate such indicators, with an emphasis on nosocomial infection indicators as a paradigm for all QIs. In this report, we review pertinent issues and, where possible, provide specific advice on how to evaluate QIs and QI systems.