Susan S. Huang

Targeted versus Universal Decolonization to Prevent ICU Infection

BACKGROUND Both targeted decolonization and universal decolonization of patients in intensive care units (ICUs) are candidate strategies to prevent health care-associated infections, particularly those caused by methicillin-resistant Staphylococcus aureus (MRSA). METHODS We conducted a pragmatic, cluster-randomized trial. Hospitals were randomly assigned to one of three strategies, with all adult ICUs in a given hospital assigned to the same strategy. Group 1 implemented MRSA screening and isolation; group 2, targeted decolonization (i.e., screening, isolation, and decolonization of MRSA carriers); and group 3, universal decolonization (i.e., no screening, and decolonization of all patients). Proportional-hazards models were used to assess differences in infection reductions across the study groups, with clustering according to hospital. RESULTS A total of 43 hospitals (including 74 ICUs and 74,256 patients during the intervention period) underwent randomization. In the intervention period versus the baseline period, modeled hazard ratios for MRSA clinical isolates were 0.92 for screening and isolation (crude rate, 3.2 vs. 3.4 isolates per 1000 days), 0.75 for targeted decolonization (3.2 vs. 4.3 isolates per 1000 days), and 0.63 for universal decolonization (2.1 vs. 3.4 isolates per 1000 days) (P=0.01 for test of all groups being equal). In the intervention versus baseline periods, hazard ratios for bloodstream infection with any pathogen in the three groups were 0.99 (crude rate, 4.1 vs. 4.2 infections per 1000 days), 0.78 (3.7 vs. 4.8 infections per 1000 days), and 0.56 (3.6 vs. 6.1 infections per 1000 days), respectively (P<0.001 for test of all groups being equal). Universal decolonization resulted in a significantly greater reduction in the rate of all bloodstream infections than either targeted decolonization or screening and isolation. One bloodstream infection was prevented per 54 patients who underwent decolonization. The reductions in rates of MRSA bloodstream infection were similar to those of all bloodstream infections, but the difference was not significant. Adverse events, which occurred in 7 patients, were mild and related to chlorhexidine. CONCLUSIONS In routine ICU practice, universal decolonization was more effective than targeted decolonization or screening and isolation in reducing rates of MRSA clinical isolates and bloodstream infection from any pathogen. (Funded by the Agency for Healthcare Research and the Centers for Disease Control and Prevention; REDUCE MRSA ClinicalTrials.gov number, NCT00980980).

Risk of Methicillin-Resistant Staphylococcus aureus Infection after Previous Infection or Colonization

Studies evaluating the risk of methicillin-resistant Staphylococcus aureus (MRSA)-associated sequelae in colonized or infected inpatients have not extended follow-up into the period after discharge from the hospital. We determined the 18-month risk of MRSA infection among 209 adult patients newly identified as harboring MRSA. Twenty-nine percent of patients (60 patients) developed subsequent MRSA infections (90 infections). These infections were often severe. Twenty-eight percent of infections (25 of 90) involved bacteremia, and 56% (50 of 90) involved pneumonia, soft tissue infection, osteomyelitis, or septic arthritis. Eighty percent of patients (48 of 60) with subsequent MRSA infection developed the infection at a new site, and 49% of new MRSA infections (44 of 90) first became manifest after discharge from the hospital. Accurate assessment of the risk of MRSA-associated sequelae requires prolonged follow-up after discharge.

Emergence of 19A as virulent and multidrug resistant pneumococcus in Massachusetts following universal immunization of infants with pneumococcal conjugate vaccine

Background: The long-term effects of selective pressure from conjugate pneumococcal vaccine on the serotype distribution and antimicrobial resistance of carriage and invasive isolates of Streptococcus pneumoniae are unknown. Early changes demonstrate a reduction in vaccine serotypes and an increase in nonvaccine serotypes (NVT) among both carriage and invasive isolates. Ongoing surveillance is necessary to identify emerging invasive serotypes and antimicrobial susceptibilities. Methods: Enhanced surveillance of invasive pneumococcal disease in Massachusetts began in October 2001 and remains ongoing. Isolates from children less than 5 are sent to the Massachusetts Department of Public Health and subsequently to the Maxwell Finland laboratory for serotyping and determination of antimicrobial susceptibility. Annual incidence rates for vaccine serotype and NVT disease are calculated using 2000 census data. Results: NVT caused 72%–91% of invasive pneumococcal disease annually in children less than 5 years of age between 2002 and 2005. Serotype 19A has emerged as the most frequent cause of IPD in Massachusetts. A multidrug-resistant clone (ceftriaxone, amoxicillin, azithromycin and trimethoprim-sulfamethoxazole) (MLST 320) was first identified in Massachusetts in 2005. Conclusions: Three years after the introduction of pneumococcal conjugate vaccine for universal administration to children less than 2 in Massachusetts, a significant increase in invasive disease due to serotype 19A was observed. Although MLST 199 remains the most frequent sequence type among invasive isolates (of 19A), a multidrug-resistant sequence type, not previously identified in Massachusetts, has become an important cause of invasive disease. Further surveillance of the changing ecology of S. pneumoniae is necessary as a 4-year time period is not sufficient to fully evaluate the impact of PCV of pneumococcal infections.

Impact of Routine Intensive Care Unit Surveillance Cultures and Resultant Barrier Precautions on Hospital-Wide Methicillin-Resistant Staphylococcus aureus Bacteremia

BACKGROUND Serial interventions are often used to reduce the risk of health care-associated methicillin-resistant Staphylococcus aureus (MRSA) infections. To our knowledge, the relative impact of these interventions has not previously been ascertained. METHODS We conducted a retrospective study of 4 major infection control interventions using an interrupted time series design to evaluate their impact on MRSA bacteremia in an 800-bed hospital with 8 intensive care units (ICUs). Interventions were introduced 1 at a time during a 9-year period and involved the promotion of compliance with maximal sterile barrier precautions during central venous catheter placement, the institution of alcohol-based hand rubs for hand disinfection, the introduction of a hand hygiene campaign, and the institution of routine nares surveillance cultures for MRSA in all ICUs for patients on ICU admission and weekly thereafter while in the ICU. Positive cultures resulted in the initiation of contact isolation precautions. Using segmented regression analyses, we evaluated changes in monthly incidence and prevalence of MRSA bacteremia from their predicted values. Methicillin-susceptible Staphylococcus aureus bacteremia was monitored as a control. RESULTS Routine surveillance cultures and subsequent contact isolation precautions resulted in substantial reductions in MRSA bacteremia in both ICUs and non-ICUs. In 16 months, the incidence density of MRSA bacteremia decreased by 75% in ICUs (P=.007) and by 40% in non-ICUs (P=.008), leading to a 67% hospital-wide reduction in the incidence density of MRSA bacteremia (P=.002). Methicillin-susceptible S. aureus bacteremia rates remained stable during this time. The other interventions were not associated with a statistically significant change in MRSA bacteremia. CONCLUSIONS Routine surveillance for MRSA in ICUs allowed earlier initiation of contact isolation precautions and was associated with large and statistically significant reductions in the incidence of MRSA bacteremia in the ICUs and hospital wide. In contrast, no similar decrease was attributable to the other infection control interventions.

Continued Impact of Pneumococcal Conjugate Vaccine on Carriage in Young Children

OBJECTIVES: The goals were to assess serial changes in Streptococcus pneumoniae serotypes and antibiotic resistance in young children and to evaluate whether risk factors for carriage have been altered by heptavalent pneumococcal conjugate vaccine (PCV7). METHODS: Nasopharyngeal specimens and questionnaire/medical record data were obtained from children 3 months to <7 years of age in primary care practices in 16 Massachusetts communities during the winter seasons of 2000–2001 and 2003–2004 and in 8 communities in 2006–2007. Antimicrobial susceptibility testing and serotyping were performed with S pneumoniae isolates. RESULTS: We collected 678, 988, and 972 specimens during the sampling periods in 2000–2001, 2003–2004, and 2006–2007, respectively. Carriage of non-PCV7 serotypes increased from 15% to 19% and 29% (P < .001), with vaccine serotypes decreasing to 3% of carried serotypes in 2006–2007. The relative contribution of several non-PCV7 serotypes, including 19A, 35B, and 23A, increased across sampling periods. By 2007, commonly carried serotypes included 19A (16%), 6A (12%), 15B/C (11%), 35B (9%), and 11A (8%), and high-prevalence serotypes seemed to have greater proportions of penicillin nonsusceptibility. In multivariate models, common predictors of pneumococcal carriage, such as child care attendance, upper respiratory tract infection, and the presence of young siblings, persisted. CONCLUSIONS: The virtual disappearance of vaccine serotypes in S pneumoniae carriage has occurred in young children, with rapid replacement with penicillin-nonsusceptible nonvaccine serotypes, particularly 19A and 35B. Except for the age group at highest risk, previous predictors of carriage, such as child care attendance and the presence of young siblings, have not been changed by the vaccine.

Risk of Infection and Death due to Methicillin- Resistant Staphylococcus aureus in Long-Term Carriers

BACKGROUND Patients with newly acquired methicillin-resistant Staphylococcus aureus (MRSA) have significant risks of short-term morbidity and mortality due to this pathogen. We were interested in assessing whether long-term carriers have persistent risks of disease and whether all carriers, regardless of the duration of carriage, should be considered to be reasonable candidates for interventions to reduce the risk of infection. METHODS We conducted a single-center retrospective cohort study to evaluate the risk of subsequent MRSA infection and death among patients known to have harbored MRSA for at least 1 year (i.e., prevalent carriers). RESULTS Among 281 prevalent carriers, 65 (23%) developed a total of 96 discrete and unrelated MRSA infections in the year after their identification as prevalent carriers. The most common infections were pneumonia (accounting for 39% of MRSA infections), soft-tissue infection (14%), and central venous catheter infection (14%). Twenty-four percent of all infections involved bacteremia. Thirty-eight MRSA infections occurred during a new hospitalization, and 32 (84%) of these infections were the reason for admission to the hospital. MRSA contributed to 14 deaths, with 6 of these deaths deemed to be attributable to MRSA. Harboring MRSA for <2 years and MRSA colonization at the time of detection as a prevalent carrier were predictive of subsequent infection with MRSA. CONCLUSIONS Individuals who are known to have harbored MRSA for >1 year are at high risk for subsequent MRSA morbidity and mortality and should be considered to be targets for intervention, in addition to individuals who have newly acquired this pathogen.

Healthcare utilization and cost of pneumococcal disease in the United States

BACKGROUND Streptococcus pneumoniae continues to cause a variety of common clinical syndromes, despite vaccination programs for both adults and children. The total U.S. burden of pneumococcal disease is unknown. METHODS We constructed a decision tree-based model to estimate U.S. healthcare utilization and costs of pneumococcal disease in 2004. Data were obtained from the 2004-2005 National (Hospital) Ambulatory Medical Care Surveys (outpatient visits, antibiotics) and the National Hospital Discharge Survey (hospitalization rates), and CDC surveillance data. Other assumptions regarding the incidence of each syndrome due to pneumococcus, expected health outcomes, and healthcare utilization were derived from literature and expert opinion. Healthcare and time costs used 2007 dollars. RESULTS We estimate that, in 2004, pneumococcal disease caused 4.0 million illness episodes, 22,000 deaths, 445,000 hospitalizations, 774,000 emergency department visits, 5.0 million outpatient visits, and 4.1 million outpatient antibiotic prescriptions. Direct medical costs totaled

Recommendations for Metrics for Multidrug-Resistant Organisms in Healthcare Settings : SHEA/HICPAC Position Paper

3.5 billion. Pneumonia (866,000 cases) accounted for 22% of all cases and 72% of pneumococcal costs. In contrast, acute otitis media and sinusitis (1.5 million cases each) comprised 75% of cases but only 16% of direct medical costs. Patients ≥ 65 years old, accounted for most serious cases and the majority of direct medical costs (

Environmental Cleaning Intervention and Risk of Acquiring Multidrug-Resistant Organisms From Prior Room Occupants

1.8 billion in healthcare costs annually). In this age group, pneumonia caused 242,000 hospitalizations, 1.4 million hospital days, 194,000 emergency department visits, 374,000 outpatient visits, and 16,000 deaths. However, if work loss and productivity are considered, the cost of pneumococcal disease among younger working adults (18-<50) nearly equaled those ≥ 65. CONCLUSIONS Pneumococcal disease remains a substantial cause of morbidity and mortality even in the era of routine pediatric and adult vaccination. Continued efforts are warranted to reduce serious pneumococcal disease, especially adult pneumonia.

Diversity and Antibiotic Resistance among Nonvaccine Serotypes of Streptococcus pneumoniae Carriage Isolates in the Post-Heptavalent Conjugate Vaccine Era

The assessment of MDRO infection and colonization should include the identification of known carriers, the detection of hospital-specific and healthcare-associated acquisition, an estimation of the burden of serious infection, an understanding of the reservoir affecting the transmission of MDROs, and an evaluation of the effect of intervention. Several strategies can be used to obtain data that aid in this assessment. We have defined and categorized the recommended metrics for each of these aspects of measuring MDRO infection and colonization, for use by healthcare facilities.