To assess the value of repeated point-prevalence surveys in measuring the trend in nosocomial infections after adjustment for case mix.

A 3,500-bed teaching facility composed of 4 acute care hospitals.

From May 1992 to June 1996, eight point-prevalence surveys of nosocomial infections were performed in the hospitals using a sampling process. The trend of adjusted nosocomial infection rates was studied for the four surveys that collected data on indwelling catheters. Adjusted rates were calculated using a logistic regression model and a direct standardization method.

From 1992 to 1996, a total of 20,238 patients were included in the 8 point-prevalence surveys. The nosocomial infection rate decreased from 8.6% in 1992 to 5% in 1996 (P < .001). The analysis of adjusted nosocomial infection rates included 9,600 patients. Four independent risk factors were identified; length of stay greater than 12 days, hospitalization in an intensive care unit, presence of an indwelling urinary catheter, and history of a surgical procedure. After adjustment for case mix, the nosocomial infection rate still showed a downward trend (from 7.2% in 1993 to 5.1% in 1996; P = .02).

Adjusted prevalence rates of nosocomial infections showed a significant downward trend during the period of this study.

This article reviews published studies of nursing home-acquired BSI in North America to determine whether there have been changes in the epidemiology of this infection in the past 20 years and to define indications for blood cultures in the nursing home setting.

A Medline search was conducted for the period from 1980 to August 2003.

Seven studies of nursing home-acquired BSI were identified. The incidence of nursing home-acquired BSI was low (0.3 episode per 1,000 resident care-days). Sources of BSI changed little during the past two decades, with urinary tract infection representing approximately 50% of the episodes. The bacteriology also did not change substantially during the past 20 years; gram-negative bacilli were isolated in approximately 50% of the episodes and Escherichia coli was the most commonly isolated organism. In the most recent study, covering the period 1997-2000, resistance to fluoroquinolones and broad-spectrum penicillins and cephalosporins was uncommon among gram-negative blood isolates; MRSA was the most common resistant organism causing nursing home-acquired BSI. Case-fatality rates changed little during the past 20 years; urinary tract infection was associated with the lowest mortality and pneumonia had the highest case-fatality rate.

There has been little change in the epidemiology of nursing home-acquired BSI in the past 20 years. Given the low incidence of BSI and the low overall yield of positive results of blood cultures (probably ≤ 6%), there is currently no support for the routine use of blood cultures in the nursing home setting.

To identify risk factors associated with surgical-site infection according to the depth of infection, the cardiac procedure, and the National Nosocomial Infections Surveillance System risk index.

Prospective survey conducted during a 12-month period.

A 48-bed cardiac surgical department in a teaching hospital.

Patients admitted for cardiac surgery between February 2002 and January 2003.

Surgical-site infections were diagnosed in 3% of the patients (38 of 1,268). Of the 38 surgical-site infections, 20 were superficial incisional infections and 18 were mediastinitis for incidence rates of 1.6% and 1.4%, respectively. Cultures were positive in 28 cases and the most commonly isolated pathogen was Staphylococcus. A National Nosocomial Infections Surveillance System risk index score of 2 or greater was associated with a risk of surgical-site infection (relative risk, 2.4; P < .004). Heart transplantation, mechanical circulatory assistance, coronary artery bypass graft with the use of internal mammary artery, and reoperation for cardiac tamponade or pericard effusion were independent risk factors associated with surgical-site infection.

Data surveillance using incidence rates stratified by cardiac procedure and type of infection is relevant to improving infection control efforts. Risk factors in patients who developed superficial infection were different from those in patients who developed mediastinitis. Coronary artery bypass graft using internal mammary artery was associated with a high risk of surgical-site infection, and independent factors such as reoperation for cardiac tamponade or pericard effusion increased the risk of infection.

Antibiotic resistance in the long-term-care facility (LTCF) setting is of increasing concern due to both the increased morbidity and mortality related to infections in this debilitated population and the potential for transfer of resistant organisms to other healthcare settings. Longitudinal trends in antibiotic resistance in LTCFs have not been well described.

Correlational longitudinal survey study.

Four LTCFs in Pennsylvania.

All clinical cultures of residents of the participating LTCFs (700 total beds) from 1998 through 2003. We assessed the annual prevalence of resistance to various antimicrobials of interest for the following organisms: Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Staphylococcus aureus, and enterococcus species.

A total of 4,954 clinical isolates were obtained during the study. A high prevalence of antimicrobial resistance was noted for many organism-drug combinations. This was especially true for fluoroquinolone susceptibility among the Enterobacteriaceae (susceptibility range, 51.3% to 92.2%). In addition, the prevalence of resistance to various agents differed significantly across study sites. Finally, significant increasing trends in resistance were noted over time and were most pronounced for fluoroquinolone susceptibility among the Enterobacteriaceae.

The prevalence of antimicrobial resistance has increased significantly in LTCFs, although trends have varied substantially across different institutions. These trends have been particularly pronounced for fluoroquinolone resistance among the Enterobacteriaceae. These findings demonstrate that antimicrobial resistance is widespread and increasing in LTCFs, highlighting the need for future studies to more clearly elucidate the risk factors for, and potential interventions against, emerging resistance in these settings.

To describe the relative proportions of nosocomial and community-onset Staphylococcus aureus bacteremia at our institution and the epidemiologic characteristics and clonal diversity of S. aureus isolates, as determined by pulsed-field gel electrophoresis (PFGE) and antimicrobial resistance patterns.

Retrospective cohort study of all cases of S. aureus bacteremia between October 2001 and October 2002.

A 1,300-bed, tertiary-care hospital.

One hundred sixty-two unique episodes of S. aureus bacteremia were identified. Forty-three cases (26.5%) were caused by methicillin-resistant S. aureus (MRSA). Most cases of S. aureus bacteremia, whether MRSA or methicillin susceptible (MSSA), were nosocomial in origin (77.2%) or were otherwise associated with the healthcare system (16%). Only 11 (6.8%) of the cases (all MSSA) were strictly community acquired. Thirty-five unique macrorestriction patterns were identified among the 154 isolates that were typed by PFGE. Four major genotypes were defined among the isolates of MRSA, with 36 (85.7%) represented by a single PFGE type. Of the isolates within this major clone, all (100%) were ciprofloxacin resistant and 77.8% were erythromycin resistant. In contrast, the 112 isolates of MSSA comprised 31 different PFGE types, 3 of which represented 42.9% of all MSSA isolates and were associated with both nosocomial and community-onset bacteremia.

Most cases of S. aureus bacteremia in our healthcare region are nosocomial in origin or are acquired through contact with the healthcare system and are thus potentially preventable. To preclude dissemination of pathogenic clones, it is therefore necessary to redouble preventive measures in both the hospital and the community.

To determine the mortality, hospital stay, and total hospital charges and cost of hospitalization attributable to candidemia by comparing patients with candidemia with control-patients who have otherwise similar illnesses. Prior studies lack broad patient and hospital representation or cost-related information that accurately reflects current medical practices.

Our case-control study included case-patients with candidemia and their cost-related data, ascertained from laboratory-based candidemia surveillance conducted among all residents of Connecticut and Baltimore and Baltimore County, Maryland, during 1998 to 2000. Control-patients were matched on age, hospital type, admission year, discharge diagnoses, and duration of hospitalization prior to candidemia onset.

We identified 214 and 529 sets of matched case-patients and control-patients from the two locations, respectively. Mortality attributable to candidemia ranged between 19% and 24%. On multivariable analysis, candidemia was associated with mortality (OR, 5.3 for Connecticut and 8.5 for Baltimore and Baltimore County; P < .05), whereas receiving adequate treatment was protective (OR, 0.5 and 0.4 for the two locations, respectively; P < .05). Candidemia itself did not increase the total hospital charges and cost of hospitalization; when treatment status was accounted for, having received adequate treatment for candidemia significantly increased the total hospital charges and cost of hospitalization ($6,000 to $29,000 and $3,000 to $22,000, respectively) and the length of stay (3 to 13 days).

Our findings underscore the burden of candidemia, particularly regarding the risk of death, length of hospitalization, and cost associated with treatment (Infect Control Hosp Epidemiol 2005;26:540-547).

To assess quantitatively the clinical impact of using an alcohol-based handrub (ABHR) in the hospital environment, measuring impact as the incidence of new, nosocomial isolates of drug-resistant organisms.

An observational survey from 1998 to 2003 comparing the first 3 years of no ABHR use with the 3 years following, when an ABHR was provided for hand hygiene.

An inner-city, tertiary-care medical center.

At baseline, an antimicrobial soap with 0.3% triclosan was provided for staff hand hygiene. The intervention was placement in all inpatient and all outpatient clinic rooms of wall-mounted dispensers of an ABHR with 62.5% ethyl alcohol. Data were collected on change in the incidence of three drug-resistant bacteria.

During the 6 years of the survey, all new, nosocomially acquired isolates of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), and Clostridium difficile-associated diarrhea were recorded. On comparison of the first 3 years with the final 3 years, there was a 21% decrease in new, nosocomially acquired MRSA (90 to 71 isolates per year; P = .01) and a 41% decrease in VRE (41 to 24 isolates per year; P < .001). The incidence of new isolates of C. difficile was essentially unchanged.

In the 3 years following implementation of an ABHR, this hospital experienced the value of reductions in the incidence of nosocomially acquired drug-resistant bacteria. These reductions provide clinical validation of the recent CDC recommendation that ABHRs be the primary choice for hand decontamination. (Infect Control Hosp Epidemiol 2005;26:650-653)

To compare ventilator-associated pneumonia (VAP) rates and patterns of isolates across studies of antibiotic and non-antibiotic methods for preventing VAP.

With the use of 42 cohort study groups as the reference standard, the prevalence of VAP was modeled in two linear regressions: one with the control groups and the other with the intervention groups of 96 VAP prevention studies. The proportion of patients admitted with trauma and the VAP diagnostic criteria were used as ecologic correlates. Also, the patterns of pathogenic isolates were available for 117 groups.

In the first regression model, the VAP rates for the control groups of antibiotic-based prevention studies were at least 18 (CI95, 12 to 24) per 100 patients higher than those in the cohort study groups (P < .001). By contrast, comparisons of cohort study groups with all other control and intervention groups in the first and second regression models yielded differences that were less than 6 per 100 and not significant (P > .05). For control groups with VAP rates greater than 35%, the patterns of VAP isolates, such as the proportion of Staphylococcus aureus, more closely resembled those in the corresponding intervention groups than in the cohort groups.

The rates of VAP in the control groups of the antibiotic prevention studies were significantly higher than expected and the patterns of pathogenic isolates were unusual. These observations suggest that inapparent outbreaks of VAP occurred in these studies. The possibility remains that antibiotic-based VAP prevention presents a major cross-infection hazard.

Methicillin-resistant Staphylococcus aureus (MRSA) has become an important nosocomial pathogen in our neonatal intensive care units (NICUs) and accounts for almost all S. aureus clinical isolates. The objective of this study was to assess the relatedness of these MRSA strains.

MRSA clinical isolates were collected from infants hospitalized in our NICUs. Pulsed-field gel electrophoresis with SmaI digestion was used to fingerprint these isolates.

Level-III NICUs in a university-affiliated children's hospital.

Between 1998 and 2000, a total of 122 MRSA clinical isolates were collected from 104 infants hospitalized in our NICUs. Fifteen infants had multiple isolates (range, 2 to 4 isolates). The sources of specimens included blood (72), pus (23), sputum (15), body fluids (3), and catheter tips (9). A total of 4 genotypes with 20 subtypes were identified. There were 2 genotypes in 1998, 2 genotypes in 1999, and 4 genotypes in 2000. All but 2 isolates belonged to either genotype A (63.1%; 7 subtypes) or genotype C (35.2%; 11 subtypes). Among the 15 infants with multiple isolates, the genotypes of the isolates from a single episode of MRSA infection were different in 2 of 12 cases, and reinfection with a new strain was noted in 3 of 5 cases with recurrent infections.

Two predominant MRSA clones prevailed in our NICUs between 1998 and 2000. Polyclonal bacteremia and reinfection with a new strain were noted.

To determine whether the conventional rate for central venous catheter (CVC)-associated bloodstream infection (BSI) accurately reflects risk for patients exposed for a variety of in situ periods.

Intensive care unit patients (n = 1,375) were monitored for 7,467 CVC-days. They were monitored until catheter removal, until diagnosis of CVC-associated BSI, or for 24 hours after discharge.

The BSI rate was 3.7 per 1,000 CVC-days. Ninety-three percent of these patients had CVCs in situ for 1-15 days. These patients were exposed to 59.7% of all CVC-days; the remaining 7% were exposed to 40.3% of all CVC-days. BSI rates stratified by exposure periods of 1-5 and 6-15 days were 2.1 and 4.5 per 1,000 CVC-days, respectively. The rates for 16-30 and 31-320 days were 10.2 and 2.1 per 1,000 CVC-days, respectively. The probability of BSI with a CVC in situ was 6 in 100 by day 15, 14 in 100 by day 25, 21 in 100 by day 30, and 53 in 100 by day 320.

The conventional aggregated rate better reflects the risk for the majority of patients rather than for patients exposed to the majority of CVC-days. It does not reflect the true probability of risk for all exposures, especially beyond 30 days. CVCs in situ from 1 to 15 days had less risk of BSI than CVCs in situ more than 15 days, which may explain why scheduled CVC replacement at days 5 to 7 has not been found beneficial.

Economic evaluation has become increasingly important in healthcare and infection control. This study evaluated the impact of nosocomial infections on cost of illness and length of stay (LOS) in intensive care units (ICUs).

A retrospective cohort study.

Medical, surgical, and mixed medical and surgical ICUs in a tertiary-care referral medical center.

Patients admitted to adult ICUs between October 2001 and June 2002 were eligible for the study.

Estimates of the cost and LOS for patients who acquired a nosocomial infection were computed using a stratified analysis and regression approach.

During the study period, 778 patients were admitted to the ICUs. Total costs for patients with and without nosocomial infections (median cost, $10,354 and $3,985, respectively) were significantly different (P < .05). The costs stratified by infection site (median differences from $4,687 to $7,365) and primary diagnosis (median differences from $5,585 to $16,507) were also significantly different (P < .05) except for surgical-site infection. After covariates were adjusted for in the multiple linear regression, nosocomial infection increased the total costs by $3,306 per patient and increased the LOS by 18.2 days per patient (P < .001). Each additional day spent in the ICU increased the cost per patient by $353 (P < .001).

Nosocomial infections are associated with increased cost of illness and LOS. Prevention of nosocomial infections should reduce direct costs and decrease the LOS.

To determine risk factors for ceftazidime-resistant Klebsiella pneumoniae infection and the effect of cef-tazidime-resistant K. pneumoniae infection on mortality during an isolated outbreak.

Case–control investigation using clinical and molecular epidemiology and prospective analysis of infection control interventions.

Surgical intensive care unit of a university-affiliated community hospital.

Fourteen case-patients infected with ceftazidime-resistant K. pneumoniae and 14 control-patients.

Ten of 14 case-patients had identical strains by pulsed-field gel electrophoresis. Broad-spectrum antibiotic therapy before admission to the unit was strongly predictive of subsequent ceftazidime-resistant K. pneumoniae infection. In addition, patients with ceftazidime-resistant K. pneumoniae infection experienced increased mortality (odds ratio, 3.77).

Cephalosporin restriction has been shown to decrease the incidence of nosocomial ceftazidime-resistant K. pneumoniae. However, isolated clonal outbreaks may occur due to lapses in infection control practices. Reinstatement of strict handwashing, thorough environmental cleaning, and repeat education led to termination of the outbreak. A distinct correlation between ceftazidime-resistant K. pneumoniae infection and mortality supports the important influence of antibiotic resistance on the outcome of serious bacterial infections.

To determine the incidence of and risk factors for surgical-site infections (SSIs) after abdominal surgery.

A cohort study was conducted from January to June 1998. CDC criteria for SSI and the NNIS System risk index were used.

A tertiary-care hospital in Peru.

Adult patients undergoing abdominal surgery who consented were enrolled and observed until 30 days after surgery. Patients who had undergone surgery at another hospital or who died or were transferred to another hospital within 24 hours after surgery were excluded.

Four hundred sixty-eight patients were enrolled. Their mean age was 37.2 years. One hundred twenty-five patients developed SSIs, 18% of which were identified after discharge. The overall incidence rate (IR) was 26.7%. The IR was 13.9% for clean, 15.9% for clean-contaminated, 13.5% for contaminated, and 47.2% for dirty interventions. The IR was 3.6% for NNIS System risk index 0 and 60% for index 3. Risk factors for SSI on logistic regression analysis were dirty or infected wound (RR, 3.8; CI95, 1.7-8.4), drain use longer than 9 days (RR, 6.0; CI95, 2.5-12.5), and length of surgery greater than the 75th percentile (RR, 2.1; CI95, 1.0-4.4). Patients with SSI had a longer hospital stay than did non-infected patients (14.0 vs 6.1 days; P < .001).

SSI is a major problem in this hospital, which has a higher IR (especially for clean interventions) than those of developed countries. In developing countries, prevention of SSI should include active surveillance and interventions targeting modifiable risk factors.

To analyze the secular trends of candidemia in a large tertiary-care hospital to determine the overall incidence, as well as the incidence by ward and by species, and to detect the occurrence of outbreaks.

Retrospective descriptive analysis. Secular trends were calculated using the Mantel-Haenszel test.

A large tertiary-care referral center in Spain with a pediatric intensive care unit (ICU) to which more than 500 children with congenital cardiac disease are admitted annually.

All patients with candidemia occurring from 1988 to 2000 were included. Cases were identified from laboratory records of blood cultures.

There were 331 episodes of candidemia. The overall incidence of nosocomial candidemia was 0.6 episode per 1,000 admissions and remained stable throughout the study period (P = .925). The species most frequently isolated was Candida albicans, but the incidence of C. parapsilosis candidemia increased (P = .035). In the pediatric ICU, the incidence of C. parapsilosis was 5.6 episodes per 1,000 admissions and it was the predominant species. Outbreaks occurred occasionally in the pediatric ICU, suggesting nosocomial transmission.

During this 13-year period, the incidence of candidemia remained stable in this hospital, but C. parapsilosis increased in frequency. Occasional outbreaks of candidemia suggested nosocomial transmission of Candida species (Infect Control Hosp Epidemiol 2005;26:548-552).

To apply two data mining algorithms (DMAs) to Food and Drug Administration (FDA) Adverse Event Reporting System (AERS) reports that involved endotoxin-like reactions with intravenous gentamicin to determine whether a signal of disproportionate reporting of these events would have been generated concurrently with surveillance based on clinical observation.

Multi-item gamma-Poisson shrinker (MGPS) and proportional reporting ratios (PRRs) were used. Data used for data mining consisted of an extract of the FDA AERS database. Previously published details of clusters of endotoxin-like reactions to intravenous gentamicin were used to select adverse events for data mining.

The first signal of disproportionate reporting with any relevant event occurred in 1998, the year in which the outbreak was identified and evaluated by the Centers for Disease Control and Prevention and the FDA. In 1997, there were only 6 reports of rigors in the AERS; this jumped to 68 in 1998. In 1998, a signal was generated for endotoxic shock with PRRs but not with MGPS, based on one case.

The two DMAs generated signals concurrently with the influx of reports. It would have been difficult for safety reviewers to ignore an increase in rigors by traditional methods of safety surveillance; therefore, DMAs might not have had a great deal to offer in this instance. If data mining were considered as a second-line defense to diligent clinical observations under similar circumstances, simple disproportionality methods such as PRRs might be more useful than DMAs such as MGPS when commonly cited thresholds are used.