To examine the effect of heterogeneous case mix for a benchmarking analysis and interhospital comparison of the prevalence rates of nosocomial infection.

Cross-sectional survey.

Eleven hospitals located in Cyprus and in the region of Crete in Greece.

The survey included all inpatients in the medical, surgical, pediatric, and gynecology-obstetrics wards, as well as those in intensive care units. Centers for Disease Control and Prevention criteria were used to define nosocomial infection. The information collected for all patients included demographic characteristics, primary admission diagnosis, Karnofsky functional status index, Charlson comorbidity index, McCabe- Jackson severity of illness classification, use of antibiotics, and prior exposures to medical and surgical risk factors. Outcome data were also recorded for all patients. Case mix-adjusted rates were calculated by using a multivariate logistic regression model for nosocomial infection risk and an indirect standardization method.

The overall prevalence rate of nosocomial infection was 7.0% (95% confidence interval, 5.9%–8.3%) among 1,832 screened patients. Significant variation in nosocomial infection rates was observed across hospitals (range, 2.2%–9.6%). Logistic regression analysis indicated that the mean predicted risk of nosocomial infection across hospitals ranged from 3.7% to 10.3%, suggesting considerable variation in patient risk. Case mix-adjusted rates ranged from 2.6% to 12.4%, and the relative ranking of hospitals was affected by case-mix adjustment in 8 cases (72.8%). Nosocomial infection was significantly and independently associated with mortality (adjusted odds ratio, 3.6 [95% confidence interval, 2.1–6.1]).

The first attempt to rank the risk of nosocomial infection in these regions demonstrated the importance of accounting for heterogeneous case mix before attempting interhospital comparisons.

To present healthcare-acquired infection surveillance data for 2001-2005 in Queensland, Australia.

Observational prospective cohort study.

Twenty-three public hospitals in Queensland.

We used computer-assisted surveillance to identify episodes of surgical site infection (SSI) in surgical patients. The risk-adjusted incidence of SSI was calculated by means of a risk-adjustment score modified from that of the US National Nosocomial Infections Surveillance System, and the incidence of inpatient bloodstream infection (BSI) was adjusted for risk on the basis of hospital level (level 1, tertiary referral center; level 2, large general hospital; level 3, small general hospital). Funnel and Bayesian shrinkage plots were used for between-hospital comparisons.

A total of 49,804 surgical patients and 4,663 patients who experienced healthcare-associated BSI.

The overall cumulative incidence of in-hospital SSI ranged from 0.28% (95% confidence interval [CI], 0%–1.54%) for radical mastectomies to 6.15% (95% CI, 3.22%–10.50%) for femoropopliteal bypass procedures. The incidence of inpatient BSI was 0.80,0.28, and 0.22 episodes per 1,000 occupied bed-days in level 1, 2, and 3 hospitals, respectively. Staphylococcus aureus was the most commonly isolated microorganism for SSI and BSI. Funnel and shrinkage plots showed at least 1 hospital with a signal indicating a possible higher-than-expected rate of S. aureus-associated BSI.

Comparisons between hospitals should be viewed with caution because of imperfect risk adjustment. It is our view that the data should be used to improve healthcare-acquired infection control practices using evidence-based systems rather than to judge institutions.

To measure the effectiveness of an industrial systems-engineering approach to a methicillin-resistant Staphylococcus aureus (MRSA) prevention program.

Before-after intervention study

An intensive care unit (ICU) and a surgical unit that was not an ICU in the Pittsburgh Veterans Administration hospital

Allpatientsadmittedtothe study units

We implemented an MRSA infection control program that consisted of the following 4 elements: (1) the use of standard precautions for all patient contact, with emphasis on hand hygiene; (2) the use of contact precautions for interactions with patients known to be infected or colonized with MRSA; (3) the use of active surveillance cultures to identify patients who were asymptomatically colonized with MRSA; and (4) use of an industrial systems-engineering approach, the Toyota Production System, to facilitate consistent and reliable adherence to the infection control program.

The rate of healthcare-associated MRSA infection in the surgical unit decreased from 1.56 infections per 1,000 patient-days in the 2 years before the intervention to 0.63 infections per 1,000 patient-days in the 4 years after the intervention (a 60% reduction; P = .003). The rate of healthcare-associated MRSA infection in the ICU decreased from 5.45 infections per 1,000 patient-days in the 2 years before to the intervention to 1.35 infections per 1,000 patient-days in the 3 years after the intervention (a 75% reduction; P = .001). The combined estimate for reduction in the incidence of infection after the intervention in the 2 units was 68% (95% confidence interval, 50%-79%; P < .001).

Sustained reduction in the incidence of MRSA infection is possible in a setting where this pathogen is endemic. An industrial systems-engineering approach can be adapted to facilitate consistent and reliable adherence to MRSA infection prevention practices in healthcare facilities.

To determine whether total and antianaerobic antibiotic exposure increases the risk of room contamination among vancomycin-resistant enterococci (VRE)–colonized patients.

A 14-month study in 2 intensive care units at an academic tertiary care hospital in Boston, Massachusetts.

All patients who acquired VRE or were VRE-colonized on admission and who had environmental cultures performed.

We performed weekly environmental cultures (2 sites per room) and considered a room to be contaminated if there was a VRE-positive environmental culture during the patient's stay. We determined risk factors for room contamination by use of the Cox proportional hazards model.

Of 142 VRE-colonized patients, 35 (25%) had an associated VRE-positive environmental culture. Patients who contaminated their rooms were more likely to have diarrhea than those who did not contaminate their rooms (23 [66%] of 35 vs 41 [38%] of 107; P = .005) and more likely to have received antibiotics while VRE colonized (33 [94%] of 35 vs 86 [80%] of 107; P = .02). There was no significant difference in room contamination rates between patients exposed to antianaerobic regimens and patients exposed to nonantianaerobic regimens or between patients with and patients without diarrhea, but patients without any antibiotic exposure were unlikely to contaminate their rooms. Diarrhea and antibiotic use were strongly confounded; although two-thirds of room contamination occurred in rooms of patients with diarrhea, nearly all of these patients received antibiotics. In multivariable analysis, higher mean colonization pressure in the ICU increased the risk of room contamination (adjusted hazard ratio per 10% increase, 1.44 [95% confidence interval, 1.04–2.04]), whereas no antibiotic use during VRE colonization was protective (adjusted hazard ratio, 0.21 [95% confidence interval, 0.05–0.89]).

Room contamination with VRE was associated with increased mean colonization pressure in the ICU and diarrhea in the VRE-colonized patient, whereas no use of any antibiotics during VRE colonization was protective.

We evaluated the effect of an antimicrobial management effort to decrease ciprofloxacin use on the antibiotic susceptibility of nosocomial Pseudomonas aeruginosa isolates.

Retrospective, observational study.

Tertiary care teaching hospital with 731 beds.

The study was conducted between January 1, 2001, and December 31, 2007. Linear regression analyses and Student t tests were used to determine significant changes in drug use among patients and antimicrobial susceptibility patterns among nosocomial P. aeruginosa isolates during the 84-month period.

Following implementation of a program to reduce oral and intravenous use of ciprofloxacin in 2005, there was a 56.6% reduction in ciprofloxacin use (P < .001). Significant reductions in the mean percentage of nosocomial P. aeruginosa isolates that were resistant to ciprofloxacin (from 45.0% to 35.2%; P < .002) and the mean incidence of ciprofloxacin resistance (from 0.77 to 0.67 isolates recovered per 1,000 patient-days; P = .03) were noted after implementation of this program. The total quantity of antipseudomonal antibiotics consumed decreased, but the use of certain antipseudomonal antibiotics (ie, cefepime and imipenem/meropenem) increased. Among nosocomial P. aeruginosa isolates, the prevalence of imipenem/meropenem resistance increased, whereas the prevalence of cefepime resistance did not. During the 84 months of the study, there was a significant association between ciprofloxacin use and the percentage of nosocomial P. aeruginosa isolates that were resistant to ciprofloxacin (p = 0.47; P = .011), but there was no correlation between ciprofloxacin use and the incidence of ciprofloxacin resistance (p = 0.21; P = .26).

Major reductions in ciprofloxacin use were associated with small but significant improvements in the rate of ciprofloxacin susceptibility among nosocomial P. aeruginosa isolates. The impact of the program on other antipseudomonal agents was variable.

To determine whether hydrogen peroxide vapor (HPV) decontamination can reduce environmental contamination with and nosocomial transmission of Clostridium difficile.

A prospective before-after intervention study.

A hospital affected by an epidemic strain of C. difficile.

Intensive HPV decontamination of 5 high-incidence wards followed by hospital-wide decontamination of rooms vacated by patients with C. difficile-associated disease (CDAD). The preintervention period was June 2004 through March 2005, and the intervention period was June 2005 through March 2006.

Eleven (25.6%) of 43 cultures of samples collected by sponge from surfaces before HPV decontamination yielded C. difficile, compared with 0 of 37 cultures of samples obtained after HPV decontamination (P < .001). On 5 high-incidence wards, the incidence of nosocomial CDAD was significantly lower during the intervention period than during the preintervention period (1.28 vs 2.28 cases per 1,000 patient-days; P = .047). The hospital-wide CDAD incidence was lower during the intervention period than during the preintervention period (0.84 vs 1.36 cases per 1,000 patient-days; P = .26). In an analysis limited to months in which the epidemic strain was present during both the preintervention and the intervention periods, CDAD incidence was significandy lower during the intervention period than during the preintervention period (0.88 vs 1.89 cases per 1,000 patient-days; P = .047).

HPV decontamination was efficacious in eradicating C. difficile from contaminated surfaces. Further studies of the impact of HPV decontamination on nosocomial transmission of C. difficile are warranted.

To evaluate hand hygiene compliance in 2 adult step-down units (SDUs).

A 6-month (from March to September 2007), controlled trial comparing 2 SDUs, one with a feedback intervention program (ie, the intervention unit) and one without (ie, the control unit).

Two 20-bed SDUs at a tertiary care private hospital.

Hand hygiene episodes were measured by electronic recording devices and periodic observational surveys. In the intervention unit, feedback was provided by the SDU nurse manager, who explained twice a week to the healthcare workers the goals and targets for the process measures.

A total of 117,579 hand hygiene episodes were recorded in the intervention unit, and a total of 110,718 were recorded in the control unit (P = .63). There was no significant difference in the amount of chlorhexidine used in the intervention and control units (34.0 vs 26.7 L per 1,000 patient-days; P = .36) or the amount of alcohol gel used (72.5 vs 70.7 L per 1,000 patient-days; P = .93). However, in both units, healthcare workers used alcohol gel more frequently than chlorhexidine (143.2 vs 60.7 L per 1,000 patient-days; P < .001). Nosocomial infection rates in the intervention and control units, respectively, were as follows: for bloodstream infection, 3.5 and 0.79 infections per 1,000 catheter-days (P = .18); for urinary tract infection, 15.8 and 15.7 infections per 1,000 catheter-days (P = .99); and for tracheostomy-associated pneumonia, 10.7 and 5.1 infections per 1,000 device-days (P = . 13). There were no cases of infection with vancomycin-resistant enterococci and only a single case of infection with methicillin-resistant Staphylococcus aureus (in the control unit).

The feedback intervention regarding hand hygiene had no significant effect on the rate of compliance. Other measures must be used to increase and sustain the rate of hand hygiene compliance.

To evaluate the antimicrobial efficacy of and risk of organisms developing resistance to 2 novel hand soaps: (1) a soap containing triclosan, polyhexamethylene biguanide, and benzethonium chloride added to a soap base (TPB soap); and (2) a soap containing farnesol, polyhexamethylene biguanide, and benzethonium chloride added to a soap base (FPB soap). Tests also included soaps containing only triclosan.

The risk of emergence of resistant bacterial mutants was investigated by determining the susceptibility changes after repeated exposure of bacteria to the drugs and soaps in vitro. The effectiveness of the soaps was evaluated using an in vitro tube dilution method, a volunteer method (the ASTM standard), and 2 pig skin methods.

The minimum inhibitory concentration and minimum bactericidal concentration of triclosan against Staphylococcus, aureus increased 8- to 62.5-fold, whereas those of TPB and FPB (both alone and in soap) were unchanged. In vitro, TPB and FPB soaps produced higher log10 reductions in colony-forming units of all tested organisms (4.95-8.58) than did soaps containing triclosan alone (0.29-4.86). In the test using the pig skin and volunteer methods, TPB soap produced a higher log10 reduction in colony-forming units (3.1-3.3) than did the soap containing triclosan alone (2.6-2.8).

The results indicate that TPB and FPB soaps may provide superior rapid and broad-spectrum efficacy with a lower risk of organisms developing resistance than do soaps containing triclosan alone. Pig skin methods may be used to predict the efficacy of antibacterial soaps in the rapid disinfection of contaminated hands. Hand washing with TPB and FPB soaps by healthcare workers and the general population may reduce the transmission of pathogens, with a lower risk of promoting the emergence of resistant organisms.

To control an outbreak of Shewanella algae and S. putrefaciens infections by identifying the risk factors for infection and transmission.

Matched case-control study.

A university-affiliated tertiary acute care hospital in Seoul, Republic of Korea, with approximately 1,600 beds.

From June 20, 2003, to January 16, 2004, a total of 31 case patients with Shewanella colonization or infection and 62 control patients were enrolled in the study.

Requirement to use single-use measuring cups and standard precautions (including hand washing before and after patient care and use of gloves).

S. algae or S. putrefaciens was isolated from blood, for 9 (29.0%) of 31 patients who acquired one of the organisms; from bile, for 8 (25.8%), and from ascitic fluid, for 8 (25.8%). The attack rate of this outbreak was 5.8% (31 patients infected or colonized, of 534 potentially exposed on ward A) and the pathogenicity of the two species together was 77.4% (24 patients infected, of 31 who acquired the pathogens). The estimated incubation period for Shewanella acquisition was 3–49 days. Using logistic analysis, we identified the following risk factors: presence of external drainage catheters in the hepatobiliary system (odds ratio [OR], 20; P < .001), presence of hepatobiliary disease (OR, 6.4; P < .001), admission to the emergency department of the hospital (OR, 2.9; P = .039), wound classification of “contaminated” or “dirty or infected” (OR, 16.5; P = .012), an American Society of Anesthesiologists score of 3 or higher (OR, 8.0; P = .006), duration of stay in ward A (OR, 1.1; P < .001), and, for women, an age of 60–69 years (OR, 13.3; P = .028). A Shewanella isolate was recovered from the surface of a shared measuring cup, and 12 isolates of S. algae showed the same pulsed-field gel electrophoresis pattern.

This Shewanella outbreak had a single-source origin and spread by contact transmission via a contaminated measuring cup. Shewanella species are emerging as potentially serious human pathogens in hospitals and could be included in hospital infection surveillance systems.

To estimate the risk of bloodstream infection associated with catheter dwell time in infants.

Retrospective study.

Duke University Medical Center neonatal intensive care unit, an academic, level 3 nursery in Durham, North Carolina.

A case of catheter-associated bloodstream infection was defined as one that occurred in an infant whose culture-positive blood sample was collected more than 24 hours after catheter insertion or within 72 hours after catheter removal. We used multivariable logistic regression to control for the catheter's position and dwell time as well as the infant's sex, gestational age, age at time of catheter insertion, birth weight, and weight at time of catheter insertion.

We identified 135 cases of catheter-associated bloodstream infection. The mean catheter dwell time was 12.2 days (range, 0–113 days), and the mean time to bloodstream infection was 10.8 days (range, 1–57 days). An increase in catheter dwell time was associated with a lower risk of bloodstream infection (odds ratio, 0.975 [95% confidence interval, 0.954–0.996]; P = .02).

increased risk of catheter-associated bloodstream infection was observed with increased catheter dwell time. This may have been due to the infant's improved nutrition, decreased need for other invasive devices, and maturing skin and immune system as catheter dwell time increased.

To identify variables contributing to interfacility differences in mortality among residents of long-term care facilities who have lower respiratory tract infection.

Multicenter, prospective, 1 -year observational study.

Twenty-one long-term care facilities in 4 geographic areas of Canada.

Residents of long-term care facilities prescribed antimicrobials for treatment of lower respiratory tract infection.

Mortality rates were calculated for 3 definitions of lower respiratory tract infection: episodes with a clinical or radiographic diagnosis and treated with antimicrobials (definition 1); episodes with a physician diagnosis of pneumonia (definition 2); and episodes with chest radiography findings consistent with pneumonia (definition 3). Multilevel modeling was used to evaluate variables describing premorbid resident status, clinical presentation, management, and facility characteristics. Multivariable models were developed to identify independent predictors of mortality and determine whether facility-level variables remained independently associated with mortality rate after incorporation of individual-level variables.

Facility mortality rates varied from 0% to 17.8% for definition 1, from 0% to 47.1% for definition 2, and from 0% to 37.5% for definition 3. There were significant differences in mortality rate depending on which definition was used; for definitions 1 and 2, there were significant differences in mortality rate across facilities. Poorer premorbid resident status and a more severe presentation remained independent predictors of mortality in the multivariable analysis. There were also significantly increased mortality rates for episodes in which a fluoroquinolone was prescribed for initial treatment. For definitions 1 and 3, facility-level variables remained independently associated with mortality rate in the final multivariable model.

Rates of mortality due to lower respiratory tract infection varied among long-term care facilities and differed within a facility, depending on the definition applied. Variables describing premorbid resident status, severity of presentation, and management did not fully explain the variation in mortality rate. Some facility-level variables remained independent predictors of mortality.