Risk assessment for surgical site infections following total hip and total knee prostheses.

The purpose of the study was to assess the relative importance of risk factors for surgical site infections (SSI) following total hip and total knee prostheses in The Netherlands. In the period 1996-99 63 hospitals in The Netherlands registered SSI after 36,629 orthopedic operations. Total hip and total knee prostheses were analyzed in detail. The results of our study showed that a long preoperative stay was a risk factor for deep SSIs after both procedures. A dirty or contaminated wound and a serious systemic condition were risk factors for deep SSIs after total hip prostheses. If post-discharge surveillance was carried out, more SSIs were found, for total knee prostheses more than twice as many. Independent risk factors for SSIs after total hip prostheses were a contaminated/dirty wound and for total knee prostheses a short operation duration. The authors conclude that surveillance of surgical site infections following total hip and total knee prostheses revealed different risk factors for (deep) SSIs.

Impact of hospital-wide surveillance on hospital-acquired infections in an acute-care hospital in the Netherlands.

The goal of surveillance is to identify hospital-acquired infections (HAI) and risk factors, to apply targeted interventions and to evaluate their effect in an ongoing system. Continuing active surveillance in a 270-bed acute-care hospital is being performed on clinical patients, excluding day-care. The period 1984-1997 is described here. Specific surveillance-based interventions included the introduction of antimicrobial prophylaxis in gynaecology patients with postoperative urinary tract catheters and inpatients scheduled for appendicectomy and hysterectomy. General measures included education, implementation of protocols, feedback of surgeon-specific infection rates. In total, 3545 HAI were found in 13 years of surveillance. The incidence was 4.7/100 admissions and 4. 5/1000 patient days. Age-specific incidences ranged from 1.3 in the age-category 1-14 years, to 10.2 in patients aged 75 years and above. If age-specific incidences had remained at their 1984 level, over 3000 additional infections would have occurred, affecting all age groups except those up to 14 years. The distribution of types of infections differed between services. Following the targeted interventions, the rate of infections in gynaecology decreased from 19.4 per 1000 patient days in 1984 to 2.4 per 1000 patient days in 1996. The rates of wound infection following appendicectomy and hysterectomy decreased by 69% and 82%, respectively, in the period following the institution of antimicrobial prophylaxis. Over 4000 micro-organisms were isolated from the HAI; multi-resistant strains were isolated sporadically. We conclude that hospital-wide surveillance of hospital-acquired infections provides appropriate targets for interventions tailored to the specific needs of the hospital. The impact of such interventions can readily be documented from the surveillance data.

An operating surveillance system of surgical-site infections in The Netherlands: results of the PREZIES national surveillance network. Preventie van Ziekenhuisinfecties door Surveillance.

OBJECTIVES: To describe the results of the first year of the Dutch national surveillance of surgical-site infections (SSIs) and risk factors, which aims to implement a standardized surveillance system in a network of Dutch hospitals, to collect comparable data on SSIs to serve as a reference, and to provide a basic infrastructure for further intervention research. DESIGN: Prospective multicenter cohort study. SETTING: Acute-care hospitals in The Netherlands from June 1996 to May 1997. RESULTS: 38 hospitals participated, with a slight over-representation of larger hospitals. Following a total of 18,063 operations, 562 SSIs occurred, of which 198 were deep. Multivariate analysis of pooled procedures shows that age, preoperative length of stay, wound contamination class, anesthesia score, and duration of surgery were independent risk factors for SSI. When analyzed by procedure, the relative importance of these risk factors changed. Bacteriological documentation was available for 56% of the SSIs; 35% of all isolates were Staphylococcus aureus. Multiple regression analysis computed the mean extra postoperative length of stay associated with SSI to be 8.2 days. CONCLUSION: The first year of national surveillance has shown that it is feasible to collect comparable data on SSI, which are already used for education, policy, and decision making in the network of participating hospitals. This gives room to effectuate the next aim, namely to use the network as an infrastructure for intervention research. Multivariate analysis shows that feedback on a procedure-specific level is important.

Risk assessment for surgical-site infections in orthopedic patients.

OBJECTIVE: To assess the relative importance of risk factors for surgical-site infections (SSIs) in orthopedic patients and thereby determine which risk factors to monitor in the national surveillance of SSI in The Netherlands. DESIGN: Reanalysis of data on SSI and associated risk factors from two surveillance projects on nosocomial infections, carried out in 1992 and 1993 in The Netherlands: Project Surveillance Nosocomial Infections in the region of Utrecht (PSZU) and the first Project Surveillance Surgical Wound Infections (SWIFT-1). Odds ratios (ORs) were calculated for age, gender, preoperative stay, and the number of operations. In addition, in PSZU, other nosocomial infections, and, in SWIFT-1, prophylactic antibiotics, acute surgery, and wound contamination were studied. PARTICIPANTS: The study was confined to hospitalized orthopedic patients (PSZU, 4,872; SWIFT-1, 6,437). RESULTS: In PSZU, the following ORs were significant in a multivariate model: age 0-44 years, 1.0; 45-64 years, 1.6; 65-74 years, 4.7; and 75-99 years, 6.0. For a preoperative stay over 4 days, the OR was 3.3 (95% confidence interval [CI95], 2.5-4.0), and for multiple surgery, 2.5 (CI95, 1.9-3.0). For females, the OR was 0.8 (not significant). The same model applied to SWIFT-1 gave similar ORs. Adjustment for additional nosocomial infections (PSZU) decreased the ORs for ages over 65 years remarkably. The OR for additional nosocomial infections in patients under 65 years of age was 15.6 (CI95, 4.3-57.4). Adjustment for prophylactic antibiotics, acute surgery, and wound-contamination class (SWIFT-1) did not influence the ORs of the original model, but showed that wound-contamination class was an important risk factor. CONCLUSIONS: Age, additional nosocomial infections, wound-contamination class, preoperative stay, and the number of operations were identified as important risk factors for SSI in Dutch orthopedic patients.

[Incidence of postoperative wound infections in The Netherlands]. / Frequentie van postoperatieve wondinfecties in Nederland.

OBJECTIVE: To inventory postoperative infections in Dutch hospitals. DESIGN: Descriptive study. SETTING: National organization for quality assurance in hospitals, Utrecht, the Netherlands. METHOD: In 36 Dutch hospitals data on surgical patients, surgical site infections and risk factors were collected, using standardised methods, as part of a quality system by which hospitals could compare their infection rates with the rates in the database. RESULTS: Surveillance of surgical site infections was introduced in 36/118 (31%) hospitals. Data on 32,869 surgical procedures were collected, 1115 (3.4%) surgical site infections were found. The infection rates by wound contamination class varied from 2.2% (95% confidence interval (CI): 2.0-2.4) in clean wounds to 11% (95% CI: 9.3-12.8) in dirty wounds; the infection rates by duration of operation varied from 3% (95% CI: 2.8-3.2) in operations lasting less than two hours to 10.8% (95% CI: 6.0-18.5) in operations lasting more than 8 hours; the infection rate by ASA classification varied from 2.7% (95% CI: 2.3-3.2) in class I to 15.5% (95% CI: 8.4-26.5) in patients in class IV. Advanced age, emergency, preoperative stay were recognised as risk factors. The infection rates in the most frequently recorded types of operation varied from 0.2% (95% CI: 0.0-1.1) in varicose veins to 9.8% (95% CI: 7.2-13.2) in femoral bypass grafts. The use of antimicrobial prophylaxis varied per type of operation. The micro-organisms most frequently isolated were Staphylococcus aureus. Staphylococcus epidermidis, Pseudomonas aeruginosa, and Escherichia coli. Of the infections 32% were identified in the first week following surgery. Of the infected patients 88% stayed in hospital during one or more days following the onset of infection.

Sentinel system for nosocomial infections in The Netherlands: a pilot study.

OBJECTIVE: To determine the feasibility of standardized surveillance of nosocomial infections (NI) in The Netherlands, using local data on patients with NI collected by infection control practitioners (ICPs) and denominator data on all patients under surveillance obtained from the Dutch National Medical Registry (LMR). DESIGN: A prospective, multicenter study. SETTING: Eight hospitals in the Utrecht region, and the National Institute of Public Health and the Environment. PATIENTS: ICPs traced NI in gynecological and orthopedic patients for 9 to 16 months. Denominator data on all patients under surveillance were obtained from the LMR. RESULTS: Data from 8,922 patients were collected; the ICPs registered 470 patients with 526 NI. Overall, the NI incidence was 5.9 per 100 patients, or 6.3 per 1,000 patient days. Urinary tract infections (UTI) were most frequent (3.3%), followed by surgical-wound infections (SWI; 2.0%) and bloodborne infections (0.12%). The incidence of both SWI and UTI differed markedly between hospitals, only partially on account of differences in patient mix (age, type of operations), antibiotic prophylaxis, and intensity of tracing methods for NI. Delay in the availability of denominator data hampered the timely feedback of incidence figures. CONCLUSIONS: Surveillance of NI in a network of sentinel hospitals offered valuable information on the occurrence of NI and on factors influencing the incidence of NI. It revealed situations in which both NI surveillance and infection control methods in individual hospitals should be improved. Obtaining denominator data on all patients from electronically registered patient discharge data greatly reduces the workload of ICPs and enables surveillance on all types of NI (all body sites and all pathogens). For timely feedback, numerator and denominator data within hospitals must be linked.

Impact of concurrent antimicrobial therapy on catheter-associated urinary tract infection.

Results of a survey in two Dutch district hospitals which investigated the impact of concurrent administration of antibiotics on the incidence of catheter-associated urinary tract infection (UTI), showed that 61% of catheterized patients received antibiotics at some stage during bladder drainage. The use of antibiotics within 48 hours prior to catheter removal reduced the risk of bacteriuria fivefold. Multivariate analysis of patients who were catheterized for 3-14 days indicated that, apart from the duration of catheter employment, the use of antibiotics was the only variable significantly and independently associated with the development of bacteriuria. The power of this association varied inversely with increasing duration of catheterization but remained significant throughout the 3-14-day interval. Patients with bacteriuria at the time of catheter removal were more likely to have a febrile illness compared to those who remained free of catheter-associated UTI.

[Registration and prevention of hospital infections in a general hospital]. / Registratie en preventie van ziekenhuisinfecties in een algemeen ziekenhuis.

Active surveillance in a 270-beds general hospital in the period 1984-1988 yielded 1,547 episodes of hospital-acquired infections among 26,079 patients admitted, i.e. 5.9 infections per 100 admissions (5.1 infections/1,000 days in the hospital). Infections of the urinary tract (3.0/100 admissions), surgical wounds (1.0%), the respiratory tract (0.8%) and bloodstream infections (0.5%) predominated. The incidence of infections was highest among patients of 75 years and older (13.0%), lowest in the age group 1-14 years (1.2%). Escherichia coli, Staphylococcus aureus, enterococci and coagulase-negative staphylococci were isolated most frequently. Specific measures to limit the occurrence of urinary tract infection resulted in a decline in the rate of hospital-acquired infections, from 7.6% in 1984 to 4.9% in 1988 (35.5%). We conclude that active surveillance of hospital-acquired infections contributes to our awareness of these infections and provides the basis for preventive action. (Micro)computers constitute important aids for these activities.

Postoperative prophylaxis with norfloxacin in patients requiring bladder catheters.

The effect of once daily doses of 200 mg oral norfloxacin on the occurrence of catheter-associated bacteriuria (greater than 1000 CFU/ml) and pyuria was studied in 105 post-operative gynaecologic patients. Norfloxacin was given from the second day after surgery until catheter removal. Bacteriuria developed in 32 of 51 (63%) control patients compared to 8 of 54 (15%) patients receiving norfloxacin (p less than 0.001). Pyuria was present in 22 of 51 (43%) control subjects versus only 3 of 54 (5%) patients treated with norfloxacin (p less than 0.001). Bacteria isolated from control patients comprised species of Enterobacteriaceae (40%), Staphylococcus (35%), and Streptococcus (17%); seven isolates were resistant to multiple antibiotics reflecting their nosocomial origin. In contrast, strains isolated from norfloxacin-treated patients comprised non-fermenting gram-negative rods (79%, usually Alcaligenes or Acinetobacter spp.) and faecal streptococci (12%). It is concluded that once daily doses of 200 mg oral norfloxacin are effective in reducing the rate of catheter-associated bacteriuria and pyuria following reconstructive gynaecologic surgery.