To determine whether patients who were colonized or infected with methicillin-resistant Staphylococcus aureus (MRSA) persistently carried the same strain and to identify the extent of strain variation within a population of patients.

Molecular typing by pulsed-field gel electrophoresis (PFGE) of stored MRSA isolates.

A Veterans Administration Medical Center with 288 hospital, 45 intermediate-care, and 75 extended-care beds.

Between January 1991 and March 1993, 91 patients had MRSA identified in routine cultures. One hundred isolates from 57 patients (63%) were available for typing.

Before 1988, only occasional MRSA isolates were identified. By 1993, 50% of S. aureus isolates from unique patients were resistant to methicillin. PFGE identified 7 MRSA strains, 3 of which were identified in specimens from 1 patient each. The most common strains were SD4 (20 patients), SD1 (12 patients), SD2 (12 patients), and SD5a (5 patients). Twenty patients had 2 or more isolates obtained at least 1 week apart (mean, 30.7 weeks; range, 1 to 102 weeks). Of these patients, 12 were colonized or infected with only one strain (mean time observed, 25.1 weeks; range, 1 to 82 weeks). Eight patients had at least 2 different strains (mean time observed, 39 weeks; range, 2 to 102 weeks).

Numerous MRSA strains circulated in tiiis endemic setting; 40% of patients observed over time were colonized or infected witii more than one strain. Molecular typing was an essential tool for evaluating the epidemiology of MRSA in this setting.

The literature is conflicted as to whether people colonized with Staphylococcus aureus are at an increased risk of mortality. The aim of this meta-analysis was to review and analyze the current literature to determine whether prior history of S. aureus colonization is associated with mortality among S. aureus-infected patients.

The PUBMED databases were searched with keywords related to S. aureus colonization and mortality. After reviewing 380 article abstracts and 59 articles in detail, only 7 studies had data on the association between S. aureus colonization and mortality among S. aureus-infected patients. Crude estimates of study odds ratios (ORs) were calculated on the basis of data from subset analyses. We pooled crude ORs from the 7 studies using a random-effects model. Woolf's test for heterogeneity was assessed.

When all studies were pooled in a random-effects model, no association between S. aureus colonization and mortality among S. aureus-infected patients was seen (pooled OR, 1.08 [95% confidence interval (CI), 0.32–3.66]; n = 7; heterogeneity P = .05). When the analyses were restricted to infection-attributable mortality, the association between colonization and mortality among S. aureus-infected patients was not statistically significant (pooled OR, 0.42 [95% CI, 0.15–1.21]; n = 4; heterogeneity P = .28).

S. aureus colonization was not associated with mortality among patients who developed an S. aureus infection. Interventions to decolonize S. aureus carriers may prevent S. aureus infections but may not be sufficient to prevent mortality.

To report a pseudoepidemic of Pseudomonas aeruginosa infections discovered during an investigation of postoperative joint infections.

A retrospective review of case patients’ hospital charts, operative reports, and laboratory data, as well as environmental culturing, polymerase chain reaction (PCR) ribotyping of outbreak isolates, and in vitro analysis of P aeruginosa growth characteristics.

A 510-bed, university-affiliated adult tertiary care hospital.

Between October 1 and December 1, 1992, seven postsurgical joint infections were diagnosed, including four caused by P aeruginosa. A bottle of “sterile” saline used to process tissue specimens was found to be contaminated with P aeruginosa. Further investigation revealed that P aeruginosa had grown from seven additional tissue cultures, all of which had been processed with the contaminated saline. PCR ribotypes of the contaminant matched those of the clinical isolates. In vitro, P aeruginosa strains were viable in commercial nonbacteriostatic saline, but never caused visible turbidity.

Six patients received antibiotics for their presumed infections; four patients had peripherally inserted central catheters placed, and one experienced severe anaphylactic reactions to several antibiotics.

Pseudoepidemics due to common organisms are often difficult to detect, and delayed recognition can result in substantial morbidity. This outbreak investigation illustrates the potential for contamination of diluents in the microbiology laboratory and emphasizes the need for meticulous quality control.

Computerized decision support systems (CDSSs) can provide indication-specific antimicrobial recommendations and approvals as part of hospital antimicrobial stewardship (AMS) programs. The aim of this study was to assess the performance of a CDSS for surveillance of invasive fungal infections (IFIs) in an inpatient hematology/oncology cohort.

Between November 1, 2012, and October 31, 2013, pediatric hematology/oncology inpatients diagnosed with an IFI were identified through an audit of the CDSS and confirmed by medical record review. The results were compared to hospital diagnostic-related group (DRG) coding for IFI throughout the same period.

A total of 83 patients were prescribed systemic antifungals according to the CDSS for the 12-month period. The CDSS correctly identified 19 patients with IFI on medical record review, compared with 10 patients identified by DRG coding, of whom 9 were confirmed to have IFI on medical record review.

CDSS was superior to diagnostic coding in detecting IFI in an inpatient pediatric hematology/oncology cohort. The functionality of CDSS lends itself to inpatient infectious diseases surveillance but depends on prescriber adherence.

Infect. Control Hosp. Epidemiol. 2015;36(11):1313–1317

To compare, in subjects undergoing general surgery, two measures of intrinsic patient risk for nosocomial infection: the Study on the Efficacy of Nosocomial Infection Control (SENIC) index and the National Nosocomial Infection Surveillance (NNIS) System index.

Prospective cohort study, with follow-up for 1 month after hospital discharge.

The general surgery service of a tertiary hospital.

Surgical-site infection.

1,483 subjects aged 10 to 92 years.

During follow-up, 155 patients developed nosocomial infection, yielding a cumulative incidence of 10.5%. The NNIS index showed a linear trend with both crude and adjusted (for SENIC index) rates of surgicalwound infection. The SENIC index did not exhibit any linear trend with adjusted (for NNIS index) rates of surgical-wound infection. To delineate whether the SENIC index added explanatory information to the NNIS index (or vice versa), we regressed each variable on the other. Logistic regression analyses confirmed the results of stratified analysis: residuals of the NNIS index added discriminating ability to the SENIC index, whereas residuals of the SENIC index did not improve the predictive power of the NNIS index.

The NNIS index had a better ability than the SENIC index for discriminating and predicting risk of surgical-wound infection

We sought to define the prevalence of tuberculin skin test (TST) positivity in a group of newly hospitalized patients, to identify risk factors for positive tests, and to examine the impact of testing on infection control practices.

Unblinded cohort study over 5 days in July 1992.

A 1,000-bed university-affiliated hospital.

All patients admitted (excluding obstetric patients and newborns) were interviewed. Patients without a history of tuberculosis (TB) or a positive TST were offered a TST with Candida and tetanus controls.

Of 346 patients offered the test, 21 (6%) had a prior history of TB or a positive TST, and 36 (10%) declined to participate; 279 of the remaining 289 completed the study. Anergy was demonstrated in 94 (33.7%) of 279 patients. New positive TSTs were identified in 19 (10.3%) of 185 nonanergic patients. Of the 19 TST-positive patients, 6 (32%) had infiltrates on chest radiographs and were evaluated for active TB. One patient was treated empirically for active TB, and five received isoniazid prophylaxis. Risk factors for a new positive TST included age (odds ratio [OR], 1.56 per decade of life; P=.021), African American race (OR, 4.81; P=.008), alcohol abuse (OR, 5.53; P=.005), and peptic ulcer disease (OR, 4.53; P=.017). Risk factors for anergy included admission to a surgical service (OR, 2.1; P=.006), current use of steroids (OR, 2.65; P=.005), and human immunodeficiency virus (HIV) infection (OR, undefined; P=.034).

Despite a high rate of anergy, routine tuberculin skin testing identified a substantial number of patients with TB infection who might otherwise have gone unrecognized.

Central-line–associated bloodstream infection (CLABSI) surveillance in home infusion therapy is necessary to track efforts to reduce infections, but a standardized, validated, and feasible definition is lacking. We tested the validity of a home-infusion CLABSI surveillance definition and the feasibility and acceptability of its implementation.

Mixed-methods study including validation of CLABSI cases and semistructured interviews with staff applying these approaches.

This study was conducted in 5 large home-infusion agencies in a CLABSI prevention collaborative across 14 states and the District of Columbia.

Staff performing home-infusion CLABSI surveillance.

From May 2021 to May 2022, agencies implemented a home-infusion CLABSI surveillance definition, using 3 approaches to secondary bloodstream infections (BSIs): National Healthcare Safety Program (NHSN) criteria, modified NHSN criteria (only applying the 4 most common NHSN-defined secondary BSIs), and all home-infusion–onset bacteremia (HiOB). Data on all positive blood cultures were sent to an infection preventionist for validation. Surveillance staff underwent semistructured interviews focused on their perceptions of the definition 1 and 3–4 months after implementation.

Interrater reliability scores overall ranged from κ = 0.65 for the modified NHSN criteria to κ = 0.68 for the NHSN criteria to κ = 0.72 for the HiOB criteria. For the NHSN criteria, the agency-determined rate was 0.21 per 1,000 central-line (CL) days, and the validator-determined rate was 0.20 per 1,000 CL days. Overall, implementing a standardized definition was thought to be a positive change that would be generalizable and feasible though time-consuming and labor intensive.

The home-infusion CLABSI surveillance definition was valid and feasible to implement.

Early replacement of a new central venous catheter (CVC) may pose a risk of persistent or recurrent infection in patients with a catheter-related bloodstream infection (CRBSI). We evaluated the clinical impact of early CVC reinsertion after catheter removal in patients with CRBSIs.

We conducted a retrospective chart review of adult patients with confirmed CRBSIs in 2 tertiary-care hospitals over a 7-year period.

To treat their infections, 316 patients with CRBSIs underwent CVC removal. Among them, 130 (41.1%) underwent early CVC reinsertion (≤3 days after CVC removal), 39 (12.4%) underwent delayed reinsertion (>3 days), and 147 (46.5%) did not undergo CVC reinsertion. There were no differences in baseline characteristics among the 3 groups, except for nontunneled CVC, presence of septic shock, and reason for CVC reinsertion. The rate of persistent CRBSI in the early CVC reinsertion group (22.3%) was higher than that in the no CVC reinsertion group (7.5%; P = .002) but was similar to that in the delayed CVC reinsertion group (17.9%; P > .99). The other clinical outcomes did not differ among the 3 groups, including rates of 30-day mortality, complicated infection, and recurrence. After controlling for several confounding factors, early CVC reinsertion was not significantly associated with persistent CRBSI (OR, 1.59; P = .35) or 30-day mortality compared with delayed CVC reinsertion (OR, 0.81; P = .68).

Early CVC reinsertion in the setting of CRBSI may be safe. Replacement of a new CVC should not be delayed in patients who still require a CVC for ongoing management.