To identify risk factors associated with surgical site infection (SSI) after pediatric posterior spinal fusion procedure by examining characteristics related to the patient, the surgical procedure, and tissue hypoxia.

Retrospective case-control study nested in a hospital cohort study.

A 475-bed, tertiary care children's hospital.

All patients who underwent a spinal fusion procedure during the period from January 1995 through December 2006 were included. SSI cases were identified by means of prospective surveillance using National Nosocomial Infection Surveillance system definitions. Forty-four case patients who underwent a posterior spinal fusion procedure and developed an SSI were identified and evaluated. Each case patient was matched (on the basis of date of surgery, ± 3 months) to 3 control patients who underwent a posterior spinal fusion procedure but did not develop an SSI. Risk factors for SSI were evaluated by univariate analysis and multivariable conditional logistic regression. Odds ratios (ORs), with 95% confidence intervals (CIs) and P values, were calculated.

From 1995 to 2006, the mean annual rate of SSI after posterior spinal fusion procedure was 4.4% (range, 1.1%—6.7%). Significant risk factors associated with SSI in the univariate analysis included the following: a body mass index (BMI) greater than the 95th percentile (OR, 3.5 [95% CI, 1.5–8.3]); antibiotic prophylaxis with clindamycin, compared with other antibiotics (OR, 3.5 [95% CI, 1.2 10.0]); inappropriately low dose of antibiotic (OR, 2.6 [95% CI, 1.0–6.6]); and a longer duration of hypothermia (ie, a core body temperature of less than 35.5°C) during surgery (OR, 0.4 [95% CI, 0.2–0.9]). An American Society of Anesthesiologists (ASA) score of greater than 2, obesity (ie, a BMI greater than the 95th percentile), antibiotic prophylaxis with clindamycin, and hypothermia were statistically significant in the multivariable model.

An ASA score greater than 2, obesity, and antibiotic prophylaxis with clindamycin were independent risk factors for SSI. Hypothermia during surgery appears to provide protection against SSI in this patient population.

To study the acquisition and cross-transmission of Staphylococcus aureus in different intensive care units (ICUs).

We performed a multicenter cohort study. Six ICUs in 6 countries participated. During a 3-month period at each ICU, all patients had nasal and perineal swab specimens obtained at ICU admission and during their stay. All S. aureus isolates that were collected were genotyped by spa typing and multilocus variable-number tandem-repeat analysis typing for cross-transmission analysis. A total of 629 patients were admitted to ICUs, and 224 of these patients were found to be colonized with S. aureus at least once during ICU stay (22% were found to be colonized with methicillin-resistant S. aureus [MRSA]). A total of 316 patients who had test results negative for S. aureus at ICU admission and had at least 1 follow-up swab sample obtained for culture were eligible for acquisition analysis.

A total of 45 patients acquired S. aureus during ICU stay (31 acquired methicillin-susceptible S. aureus [MSSA], and 14 acquired MRSA). Several factors that were believed to affect the rate of acquisition of S. aureus were analyzed in univariate and multivariate analyses, including the amount of hand disinfectant used, colonization pressure, number of beds per nurse, antibiotic use, length of stay, and ICU setting (private room versus open ICU treatment). Greater colonization pressure and a greater number of beds per nurse correlated with a higher rate of acquisition for both MSSA and MRSA. The type of ICU setting was related to MRSA acquisition only, and the amount of hand disinfectant used was related to MSSA acquisition only. In 18 (40%) of the cases of S. aureus acquisition, cross-transmission from another patient was possible.

Colonization pressure, the number of beds per nurse, and the treatment of all patients in private rooms correlated with the number of S. aureus acquisitions on an ICU. The amount of hand disinfectant used was correlated with the number of cases of MSSA acquisition but not with the number of cases of MRSA acquisition. The number of cases of patient-to-patient cross-transmission was comparable for MSSA and MRSA.

Increasing length of hospital stay is associated with methicillin-resistant Staphylococcus aureus (MRSA) acquisition. The exact risk of becoming colonized with MRSA on a given day has not been clearly elucidated. We determined the hazard of MRSA acquisition in relation to the length of time spent in an intensive care unit in which only standard precautions were used for MRSA-colonized and MRSA-infected patients.

This study took place at a tertiary referral hospital intensive care unit in which patients were screened for MRSA at hospital admission, at hospital discharge, and twice weekly during intensive care unit stay. We analyzed the hazard of MRSA acquisition by using a statistical smoothing kernel for hazard with a width of 5 days. Patients were stratified according to age, sex, medical unit, and length of hospital stay.

Of the patients who were at risk of colonization or infection, 12.8% acquired MRSA. The mean length of stay in the intensive care unit was 7.2 days. The daily hazard of acquiring MRSA was less than 1% at admission to the intensive care unit and increased linearly to more than 2% risk per day by day 12, followed by a leveling out of risk.

The daily hazard of acquiring MRSA is not constant. This has implications for studies that assume a constant hazard in their analysis and should be considered.

To describe the incidence of recovery of both vancomycin-resistant enterococci (VRE) and methicillin-resistant Staphylococcus aureus (MRSA) from culture of a single clinical specimen, to describe the clinical characteristics of patients from whom these specimens were recovered, and to identify the risk factors of these patients.

A retrospective cohort and case-control study.

A tertiary care university hospital and referral center in Seoul, Korea.

We identified 61 case patients for whom a single clinical specimen yielded both VRE and MRSA on culture, and 122 control patients for whom any clinical specimen yielded only VRE on culture. The control patients were selected by matching 2 :1 with the case patients for age, sex, and first date of sampling that led to isolation of VRE or both VRE and MRSA among 1,536 VRE-colonized patients from January 1, 2003, through December 31, 2006. To identify patient risk factors for the recovery of both VRE and MRSA in a single clinical specimen, we performed univariate comparisons between the 2 groups and then multivariate logistic regression analysis.

The incidence of recovery of both VRE and MRSA from culture of a single clinical specimen was 3.97% (for 61 of 1,536 VRE-colonized patients) over 4 years. Among these 82 single clinical specimens, the most common type was wound specimens (26.8%), followed by lower respiratory tract specimens (18.3%), urine specimens (17.1%), and catheter tips (15.9%). Of the 61 case patients, 14 (23.0%) had 2 or more single clinical specimens that yielded both VRE and MRSA on culture, and the longest interval from the first sampling that yielded both organisms to the last sampling that yielded both was 174 days. Independent patient risk factors for the presence of both VRE and MRSA in a single clinical specimen were chronic renal disease (odds ratio [OR], 7.00; P = .012), urinary catheterization (OR, 3.36; P = .026), and longer total cumulative duration of hospital stay within the previous year (OR, 1.03; P < .001).

We confirmed that the recovery of VRE and MRSA from a single clinical specimen occurs continually. Because prolonged cell-to-cell contact can facilitate transfer of vanA, close observation and surveillance for vancomycin-resistant S. aureus, especially among patients with risk factors for the recovery of both VRE and MRSA from a single clinical specimen, should be continued.

To identify risk factors associated with nosocomial bloodstream infections caused by multiple clones of the staphylococcal cassette chromosome mec (SCCmec) type IV strain of methicillin-resistant Staphylococcus aureus (MRSA).

An unmatched case-control study (at a ratio of 1:2) performed during the period from October 2002 through September 2003.

A 2,000-bed tertiary care teaching hospital affiliated with the University of São Paulo in São Paulo, Brazil.

Case patients (n = 30) were defined either as patients who had a bloodstream infection due to SCCmec type IV MRSA diagnosed at least 48 hours after hospital admission or as neonates with the infection who were born in the hospital. Control patients (n = 60) were defined as patients with SCCmec type III MRSA infection diagnosed at least 48 hours after hospital admission. Genes encoding virulence factors were studied in the isolates recovered from case patients, and molecular typing of the SCCmec type IV MRSA isolates was also done by pulsed-field gel electrophoresis and multilocus sequence typing.

In multivariate analysis, the following 3 variables were significantly associated with having a nosocomial bloodstream infection caused by SCCmec type IV strains of MRSA: an age of less than 1 year, less frequent use of a central venous catheter (odds ratio [OR], 0.07 [95% confidence interval {CI}, 0.02–0.28]; P = .001), and female sex. A second analysis was performed that excluded the case and control patients from the neonatal unit, and, in multivariate analysis, the following variables were significantly associated with having a nosocomial bloodstream infection caused by SCCmec type IV strains of MRSA: less frequent use of a central venous catheter (OR, 0.12 [95% CI, 0.03–0.55]; P = .007), lower Acute Physiology and Chronic Health Evaluation II score on admission (OR, 0.14 [95% CI, 0.03–.61]; P = .009), less frequent surgery (OR, 0.21 [95% CI, 0.06–0.83]; P = .025), and female sex (OR, 5.70 [95% CI, 1.32–24.66]; P = .020). Of the 29 SCCmec type IV MRSA isolates recovered from case patients, none contained the Panton-Valentine leukocidin, λ-hemolysin, enterotoxin B or C, or toxic shock syndrome toxin-1. All of the isolates contained genes for the LukE-LukD leukocidin and α-hemolysin. Genes for enterotoxin A were present in 1 isolate, and genes for β-hemolysin were present in 3 isolates.

“Classical” risk factors do not apply to patients infected with the SCCmec type IV strain of MRSA, which is an important cause of nosocomial bacteremia. This strain infects a patient population that is less ill and has had less frequent invasive procedures than a patient population infected with the multidrug-resistant strain of SCCmec type III MRSA. We found that virulence factors were rare and that Panton-Valentine leukocidin was absent. There were multiple clones of the SCCmec type IV strain in our hospital. Children under 1 year of age were at a higher risk. There was a predominant clone (sequence type 5) in this patient population.

The prevalence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) strains causing bloodstream infection (BSI) has not been studied in Korea.

We sought to determine the prevalence of CA-MRSA strains among isolates recovered from patients with MRSA BSIs and to explore epidemiological changes in Korea. We also sought to evaluate clinical characteristics relevant to the development of healthcare-associated BSIs.

We prospectively collected consecutive MRSA isolates from patients with BSI at 4 hospitals from July 1 through November 30, 2007, and we also included MRSA isolates recovered from culture of blood samples collected during a previous year (October 1, 2004 through September 30, 2005) at a different hospital. Molecular typing studies were performed, including pulsed-field gel electrophoresis (PFGE), multilocus sequence typing, Staphylococcus protein A (spa) typing, and staphylococcal cassette chromosome mec (SCCmec) typing. We compared the clinical characteristics and outcomes of patients with healthcare-associated BSI due to CA-MRSA strains with those of patients with healthcare-associated BSI due to healthcare-associated MRSA (HA-MRSA) strains.

There were 76 cases of MRSA BSI, of which 4 (5.3%) were community-associated and 72 (94.7%) were healthcare-associated. Among the 72 HA-MRSA BSIs, 18 (25%) were community onset, and 54 (75%) were hospital onset. PFGE type D-ST72–spa B-SCCmec type IVA MRSA, the predominant genotype of CA-MRSA in Korea, accounted for 19 (25%) of all 76 MRSA BSIs, including 17 (23.6%) of 72 HA-MRSA BSIs and 11 (20.8%) of 53 hospital-onset HA-MRSA BSIs. Patients with healthcare-associated BSIs due to CA-MRSA strains carrying SCCmec type IVA tended to have fewer healthcare-associated risk factors, compared with patients with healthcare-associated BSIs due to HA-MRSA strains carrying other SCCmec types. The presence of a central venous catheter or other invasive device was the only independent factor differentiating patients infected with hospital-associated genotype strains from patients infected with other strains. Clinical outcomes were similar between both groups.

CA-MRSA strains are emerging as a major cause of BSI in healthcare settings in Korea. This changing epidemiology of MRSA poses a challenge to public health and infection control in hospital settings.

At the end of 2002, a new, more virulent strain of Clostridium difficile, designated BI/NAP1, was the cause of a massive outbreak of infection in the province of Quebec. This particular strain was associated with a dramatic increase in morbidity and mortality among affected patients in 2003–2004. We tested and implemented a multipronged infection control approach to curtail the rate of C. difficile infection (CDI).

Five-year observational study.

A 554-bed, acute care tertiary hospital, the largest single medical center in Quebec, Canada.

To curtail the magnitude of the outbreak, we implemented a global strategy consisting of rapid C. difficile testing for all hospitalized patients who had at least 1 occurrence of liquid stool, the rapid isolation of patients infected with C. difficile in a dedicated ward with a specially trained housekeeping team, a global hand hygiene program, and the hiring of infection control practitioners. Antibiotic consumption at the institutional level was also monitored during the 5-year surveillance period. Cases of hospital-acquired CDI per 1,000 admissions were continuously monitored on a monthly basis during the entire surveillance period.

The highest recorded CDI rate was 42 cases per 1,000 admissions in January 2004. Once additional infection control resources were put in place, the rate descreased significantly during the period from April 2005 to March 2007. During the 2003–2004 period, there were 762 cases of CDI (mean annual rate, 37.28 cases per 1,000 admissions) recorded in our study, compared with 292 cases of CDI (14.48 cases per 1,000 admissions) during the 2006–2007 period (OR, 0.379 [95% CI, 0.331–0.435]; P < .001 ), a 61% reduction. In March 2007, the equivalent of 4 full-time equivalent infection control practitioners were in place, which gave a ratio of 0.96 infection control practitioners per 133 beds in use, compared with the ratio of 0.24 infection control practitioners per 133 beds in use in 2003, and the total number of hours dedicated to cleaning and housekeeping increased by 26.2%. The total amount of antibiotics used in the hospital did not vary significantly from 2002 to 2007, although there were changes in the classes antibiotic used.

The implementation of a multipronged intervention strategy to control the outbreak of CDI significantly improved the overall situation at the hospital and underlined the importance of investing in stringent infection control practices.

To describe and measure reliability of a computer-assisted method of case vignette assembly and expert review to assess the appropriateness of antimicrobial therapy for hospitalized adults.

Feasibility and reliability analysis of computer-assisted tool used to compare the effects of antimicrobial stewardship interventions.

Public teaching hospital.

Randomly selected adult antimicrobial recipients admitted to inpatient medicine services.

Clinical data abstracted from 504 paper medical records were merged with computerized laboratory and pharmacy data to assemble case vignettes that underwent expert review for appropriateness. We performed 3 validations, as follows: data for 35 vignettes abstracted independently by 2 research assistants were assessed for interrater agreement, expert review of 24 vignettes was compared with review of the corresponding paper medical records, and interrater reliability of antimicrobial appropriateness assessments by 2 experts was determined for 70 case vignettes.

Vignette assembly and expert review each required 10–12 minutes per case. Potentially important discrepancies occurred in 0%–32% of clinical findings abstracted independently by 2 research assistants. Expert review of 24 vignettes and the corresponding full paper medical records yielded fair agreement (kappa, 0.30). The 2 experts identified inappropriate initial antimicrobial therapy in 67% and 61% of case vignettes reviewed independently; interrater agreement was improved after sequential case discussion and stringent application of appropriateness criteria (kappa, 0.72).

Our case vignette assembly and expert review method is efficient, but improvements in both technical and human performance are needed to be able to yield valid estimates of the prevalence of inappropriate antimicrobial use. Assessments of antimicrobial appropriateness require validation.

To investigate the rate of adherence by hospital staff members to the correct use of alcohol-based hand rub before and after performance of clinical procedures.

A cohort study conducted during the period from 2006 through 2007 and 2 cross-sectional studies conducted in 2006 and 2007.

Århus University Hospital, Skejby, in Århus, Denmark.

Various hospital staff members.

Following an ongoing campaign promoting the correct use of alcohol-based hand rub, we observed rates of adherence by hospital staff to the correct use of alcohol-based hand rub. Observations were made before and after each contact with patients or patient surroundings during 5 weekdays during the period from 2006 through 2007 in 10 different hospital units. A logistic regression model was used to estimate the rate of adherence to the correct use of alcohol-based hand rub before and after performance of a clinical procedure.

A total of 496 participants were observed during 22,906 opportunities for hand hygiene (ie, 11,177 before and 11,729 after clinical procedures) that required the use of alcohol-based hand rub. The overall rates of adherence to the correct use of alcohol-based hand rub were 62.3% (6,968 ofthe 11,177 opportunities) before performance and 68.6% (8,041 ofthe 11,729 opportunities) after performance of clinical procedures. Compared with male participants, female participants were significantly better at adhering to the correct use of alcohol-based hand rub before performance (odds ratio [OR] 1.51 [95% confidence interval {CI}, 1.09–2.10]) and after performance (OR, 1.73 [95% CI, 1.27–2.36]) of clinical procedures. In general, the rate of adherence was significantly higher after the performance of clinical procedures, compared with before (OR, 1.43 [95% CI, 1.35–1.52]). For our cohort of 214 participants who were observed during 14,319 opportunities, the rates of adherence to the correct use of alcohol-based hand rub were 63.2% (4,469 of the 7,071 opportunities) before performance and 69.3% (5,021 of the 7,248 opportunities) after performance of clinical procedures, and these rates increased significantly from 2006 to 2007, except for physicians.

We found a high and increasing rate of adherence to the correct use of alcohol-based hand rub before and after performance of clinical procedures following a campaign that promoted the correct use of alcohol-based hand rub. More hospital staff performed hand hygiene with alcohol-based hand rub after performance of clinical procedures, compared with before performance. Future campaigns to improve the rate of adherence to the correct use of alcohol-based hand rub ought be aware that certain groups of hospital staff (eg, male staff members) are known to exhibit a low level of adherence to the correct use of alcohol-based hand rub.

The sterility assurance level of 10−6 is an established standard that defines the quality of sterile products. The aim of the present study was to develop a method that correlated the results from microbial-barrier testing of flexible sterile barrier systems with the estimated microbial challenge that the package encounters during storage and transport.

The effectiveness of microbial-barrier packaging was determined by the use of an exposure chamber test with 20 periodic atmospheric pressure changes of 50 and 70 hPa. Flexible peel pouches were used as sterile barrier systems. The logarithmic reduction value of a sterile barrier system was calculated on the basis of the experimental results and compared with the logarithmic reduction value required for the microbial challenges to maintain sterility during transport and storage.

For pouches made of paper and plastic-film material, a logarithmic reduction value of 5.4 was obtained on the basis of 30 of 99 plates becoming nonsterile after being exposed to a 50 hPa difference in periodic atmospheric pressure changes. For pouches made of paper and plastic-film material, a logarithmic reduction value of 5.2 was obtained on the basis of 48 of 100 plates becoming nonsterile after being exposed to a 70 hPa difference in atmospheric pressure. For pouches made of nonwoven and plastic-film material, logarithmic reduction values of 6.38 (ie, 3 of 99 plates became nonsterile after being exposed to a 50 hPa pressure difference) and 6.07 (ie, 3 of the 99 plates became nonsterile after being exposed to a 70 hPa pressure difference) were obtained. Calculating an expected microbial challenge during transport and storage that requires barrier properties corresponding to a logarithmic reduction value of 5.83 and taking the sterility assurance level into account, we found that only the nonwoven pouches fulfilled the European standard EN 556-1.

Using the data obtained in a microbial exposure test with a specified flow rate of a bacterial aerosol, we found that the effectiveness of the sterile barrier system against the actual microbial challenge can be examined and evaluated at the sterility assurance level of 10−6.