Rupak Datta

University of California, Irvine, Irvine, California, United States

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Publications (22)98.94 Total impact

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    ABSTRACT: Background. States have established public reporting of hospital-associated (HA) infections-including those of methicillin-resistant Staphylococcus aureus (MRSA)-but do not account for hospital case mix or postdischarge events. Objective. Identify facility-level characteristics associated with HA-MRSA infection admissions and create adjusted hospital rankings. Methods. A retrospective cohort study of 2009-2010 California acute care hospitals. We defined HA-MRSA admissions as involving MRSA pneumonia or septicemia events arising during hospitalization or within 30 days after discharge. We used mandatory hospitalization and US Census data sets to generate hospital population characteristics by summarizing across admissions. Facility-level factors associated with hospitals' proportions of HA-MRSA infection admissions were identified using generalized linear models. Using state methodology, hospitals were categorized into 3 tiers of HA-MRSA infection prevention performance, using raw and adjusted values. Results. Among 323 hospitals, a median of 16 HA-MRSA infections (range, 0-102) per 10,000 admissions was found. Hospitals serving a greater proportion of patients who had serious comorbidities, were from low-education zip codes, and were discharged to locations other than home were associated with higher HA-MRSA infection risk. Total concordance between all raw and adjusted hospital rankings was 0.45 (95% confidence interval, 0.40-0.51). Among 53 community hospitals in the poor-performance category, more than 20% moved into the average-performance category after adjustment. Similarly, among 71 hospitals in the superior-performance category, half moved into the average-performance category after adjustment. Conclusions. When adjusting for nonmodifiable facility characteristics and case mix, hospital rankings based on HA-MRSA infections substantially changed. Quality indicators for hospitals require adequate adjustment for patient population characteristics for valid interhospital performance comparisons.
    Infection Control and Hospital Epidemiology 10/2014; 35(10):1263-1270. · 4.02 Impact Factor
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    ABSTRACT: Observational studies rarely account for confounding by indication, whereby empiric antibiotics initiated for signs and symptoms of infection prior to the diagnosis of infection are then viewed as risk factors for infection. We evaluated whether confounding by indication impacts antimicrobial risk factors for methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) acquisition.
    Antimicrobial resistance and infection control. 01/2014; 3:19.
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    ABSTRACT: In a retrospective cohort study of 1,140 patients harboring methicillin-resistant Staphylococcus aureus, nasal burden was few in 31%, 1+/2+ in 54%, and 3+/4+ in 15%. There was a significant trend in infection risk with increasing nasal burden (p=.007). In multivariate models, high nasal burden remained significantly associated with invasive infection.
    Journal of clinical microbiology 10/2013; · 4.16 Impact Factor
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    ABSTRACT: BACKGROUND: California hospitals are mandated to report hospital-associated Clostridium difficile infection (HA-CDI) rates. However, risk adjustment methods are limited. We sought to identify readily-available facility-level adjustors for HA-CDI rates in California hospitals. METHODS: We conducted a retrospective cohort study of all California hospitals between April 2010 and March 2011. HA-CDI rates were derived from 2010-2011 data reported to the National Healthcare Safety Network. We used 2009-2010 patient discharge datasets from the California Office of Statewide Health Planning and Development and 2005-2010 U.S. Census American Community Survey data to generate hospital population characteristics. Information on hospital type, teaching status, and laboratory testing method were also included. We used Least Absolute Shrinkage and Selection Operator regression with 10-fold cross validation for initial variable selection. Facility-level predictors were then assessed using multivariate Poisson regression testing. RESULTS: We identified hospital population characteristics for 366 hospitals reporting HA-CDI rates. One outlier facility was excluded. The median number of admissions was 7,933. 6% were teaching hospitals, 5% long-term acute care hospitals, and 28% used PCR. Overall, the mean HA-CDI rate was 8.3 cases per 10,000 patient-days (range, 0 to 29.8). In final regression models, variables associated with HA-CDI included increased number of hospital beds (incidence rate ratio (IRR) = 1.08, 95% CI: 1.05-1.11), teaching status (IRR=1.25, 95% CI: 1.04-1.51), PCR testing method (IRR=1.12, 95% CI: 1.00-1.25), and increased annual admissions involving patients ≥ 85 years (IRR=1.36, 95% CI: 1.12-1.66), increasing comorbidity index (IRR=1.37, 95% CI: 1.18-1.59), increasing admissions with infections (proxy for antibiotic use, IRR=1.44, 95% CI: 1.00-1.16), and commercially-insured patients (IRR=1.16, 95% CI: 1.08-1.25). CONCLUSIONS: HA-CDI rates in California hospitals are associated with multiple facility-level characteristics including hospital volume, C. difficile testing method, insurance type, and patient case mix. These results suggest that risk-adjustment for non-modifiable factors such as patient population age, comorbidity index, reasons for admission, and insurance type maybe important for valid inter-hospital comparisons of HA-CDI rates.
    2013 Council of State and Territorial Epidemiologists Annual Conference; 06/2013
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    ABSTRACT: Background. Central line-associated bloodstream infection (CLABSI) is a national target for mandatory reporting and a Centers for Medicare and Medicaid Services target for value-based purchasing. Differences in chart review versus claims-based metrics used by national agencies and groups raise concerns about the validity of these measures. Objective. Evaluate consistency and reasons for discordance among chart review and claims-based CLABSI events. Methods. We conducted 2 multicenter retrospective cohort studies within 6 academic institutions. A total of 150 consecutive patients were identified with CLABSI on the basis of National Healthcare Safety Network (NHSN) criteria (NHSN cohort), and an additional 150 consecutive patients were identified with CLABSI on the basis of claims codes (claims cohort). All events had full-text medical record reviews and were identified as concordant or discordant with the other metric. Results. In the NHSN cohort, there were 152 CLABSIs among 150 patients, and 73.0% of these cases were discordant with claims data. Common reasons for the lack of associated claims codes included coding omission and lack of physician documentation of bacteremia cause. In the claims cohort, there were 150 CLABSIs among 150 patients, and 65.3% of these cases were discordant with NHSN criteria. Common reasons for the lack of NHSN reporting were identification of non-CLABSI with bacteremia meeting Centers for Disease Control and Prevention (CDC) criteria for an alternative infection source. Conclusion. Substantial discordance between NHSN and claims-based CLABSI indicators persists. Compared with standardized CDC chart review criteria, claims data often had both coding omissions and misclassification of non-CLABSI infections as CLABSI. Additionally, claims did not identify any additional CLABSIs for CDC reporting. NHSN criteria are a more consistent interhospital standard for CLABSI reporting.
    Infection Control and Hospital Epidemiology 02/2013; 34(2):176-83. · 4.02 Impact Factor
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    ABSTRACT: We calculated hospital-onset methicillin-resistant Staphylococcus aureus (HO-MRSA) rates for Orange County, California, hospitals using survey and state data. Numerators were variably defined as HO-MRSA occurring more than 48 hours (37%), more than 2 days (30%), and more than 3 days (33%) postadmission. Survey-reported denominators differed from state-reported patient-days. Numerator and denominator choices substantially impacted HO-MRSA rates.
    Infection Control and Hospital Epidemiology 11/2012; 33(11):1166-9. · 4.02 Impact Factor
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    ABSTRACT: Background: Many studies have reported an association between antibiotic exposure and MRSA or VRE acquisition in hospitals. However, these studies have not accounted for confounding by indication, whereby empiric antibiotics are given for symptoms ultimately due to an MRSA or VRE infection. Methods: We previously reported several predictors of MRSA and VRE acquisition in a case control study of intensive care unit (ICU) patients admitted to a tertiary care center between Sep 2003 and Apr 2005 who had an initial negative nares or rectal screening culture followed by either a subsequent negative screening culture (controls) or positive screening or clinical culture (cases).1 Cases and controls were selected at a 1:1 ratio. Within and prior to this eligible interval for acquisition, detailed data had been collected, including demographics, comorbidities, and daily device and antibiotic utilization. We now conduct a secondary analysis in which antibiotics given for symptoms ultimately attributed to MRSA or VRE infection are removed. Remaining antibiotic exposures are classified into the following periods: during the eligible interval, 2 weeks prior to the interval, or 2 months prior to the interval. Generalized linear mixed models are used to assess variables associated with MRSA or VRE acquisition, accounting for clustering by ICU. Results: Among 244 cases and 248 controls for MRSA acquisition, we find that exclusion of empiric antibiotics used for MRSA infection affects 113 cases resulting in different antibiotic predictors of acquisition (Table). In contrast, among 227 cases and 248 controls for VRE, similar exclusion affects 5 cases and has no impact on predictors. Antibiotic exposure in the prior 2 weeks appears most associated with MRSA acquisition, whereas exposure in the prior 2 months appears most associated with VRE acquisition. Conclusion: Failure to account for treatment indication when assessing antibiotic exposures may cause common empiric antibiotics to falsely appear predictive of MRSA acquisition. This effect is not seen for VRE, likely because VRE infection (and thus empiric therapy) is less common. Timing of antibiotic exposure may also be important. 1Huang et al. Critical Care 2011, 15:R210
    IDWeek 2012 Meeting of the Infectious Diseases Society of America; 10/2012
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    ABSTRACT: Background: S. aureus nasal colonization generally precedes infection and high quantitative nasal counts have been shown to increase risk for surgical site infection for MSSA. Our goal was to assess whether high levels of nasal MRSA growth increases the risk for MRSA blood and urine infection. Methods: We conducted a retrospective cohort study of adults admitted to the University of California Irvine Medical Center who were newly-detected to harbor MRSA by nasal screening cultures between March 1, 2008 and June 30, 2011. The routine report of semi quantitative MRSA were classified into three groups: “rare/few”, “1+/2+”, and “3+/4+”, corresponding to logarithmic increases in growth. Collected cohort characteristics included age, gender, ICU admission, surgical procedure, and comorbidities from ICD9 codes. Patients decolonized with mupirocin were excluded. Bivariate tests (χ2 test) were used to assess the association between these variables and the outcome of any MRSA blood or urine culture within 6 months. Variables with α < .2 in bivariate testing were assessed by logistic regression. Final model variables with α < .05 are shown. Results: The cohort of 1,140 adults with newly-detected MRSA had a mean age of 58y, 59% male, 19.2% with diabetic, 7.7% liver disease, 10.5% renal disease. MRSA growth was rare/few in 356 (31%), 1+/2+ in 621 (54%), and 3+/4+ in 169 (15%). Overall, 58 (5.1%) patients developed a subsequent MRSA blood or urine culture within 6 months; the mean time to infection was 24 days. Factors significantly associated with subsequent MRSA infection in multivariate models included length of initial hospital stay, and MRSA nasal burden (Table). Table. Predictors of MRSA Invasive Disease* Odds Ratio (CI) P-value MRSA Nasal Burden 0.028 Rare/few -- 1+/2+ 2.1 (1.0, 4.3) 3+/4+ 3.2 (1.4, 7.6) Length of Stay <0.0001 1 - <3 - 3 - <5 1.1 (0.5, 2.6) 5 - <7 0.4 (0.1, 1.9) 7 - <10 1.4 (0.5, 4.0) >10 3.8 (1.9, 7.6) * Also adjusted for age, diabetes, renal disease (p = NS) Conclusion: Inpatients with high nasal MRSA colonization burden are at higher risk of subsequent invasive infections. This high risk group may benefit from targeted decolonization to reduce disease. **Co-first author, A Shah and R Datta
    IDWeek 2012 Meeting of the Infectious Diseases Society of America; 10/2012
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    ABSTRACT: Background: Hospital readmission rates are publicly reported and subject to financial penalty by the Centers for Medicare and Medicaid Services. Many hospital readmissions are due to infection, and knowledge of hospital patient population characteristics associated with infectious readmissions may inform prevention strategies. The primary aim of this study was to identify hospital characteristics associated with readmissions due to infection within 30 days of hospital discharge. Methods: We conducted a retrospective cohort study of patients discharged from all California (CA) hospitals between September 1, 2009-August 31, 2010 and assessed all readmissions within 30 days. We used mandatory CA discharge data to generate hospital patient population characteristics by summarizing descriptors across all admissions. We then used the primary or secondary diagnosis code for each admission to identify readmissions due to bacterial infection. Bivariate linear regression models were used to identify associations between hospital characteristics and readmission due to infection. Variables with p<0.1 were entered into a multivariate linear regression model with variables retained at p<0.05. Results: We identified 316 hospitals with 2,841,894 adult admissions during the study period. Across all hospitals, 3.7% of all admissions were followed by readmission due to infection within 30 days (range 0.3-10.3%). The mean time to infection readmission was 11 days, and the most common diagnoses identified were pneumonia and septicemia. Table 1 shows hospital and patient population characteristics associated with 30-day readmission due to infection. Conclusion: Approximately 4% of admissions to CA hospitals are followed by readmission due to infection within 30 days, with wide variation among facilities. Variation is partly attributable to differences in comorbidities, age, and insurance across hospital populations. Financial incentive plans for preventing readmissions, including those from healthcare-associated infections, should adjust for non-modifiable risk factors among hospital populations. *Co-first authors: Shruti Gohil, MD, MPH and Rupak Datta, MPH
    IDWeek 2012 Meeting of the Infectious Diseases Society of America; 10/2012
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    ABSTRACT: Background: California hospitals are mandated to report HA-CDI rates. However, risk adjustment methods for HA-CDI rates have not yet been developed. We sought to identify facility-level characteristics associated with publicly reported HA-CDI rates in CA acute care hospitals Methods: We conducted a retrospective cohort study of all CA hospitals to evaluate facility level factors associated with HA-CDI rates reported between April 1, 2010 and March 31, 2011. We used 2010 mandatory state discharge data to generate hospital patient population characteristics by summarizing variables across all admissions. We also included data on hospital type, teaching status and laboratory method of CDI testing. We evaluated hospital level factors associated with HA-CDI rates using bivariate linear regression models. Variables with p<0.1 were entered into a multivariate linear regression model. Final variables were retained at p<.05. Results: Between April 2010 and March 2011, we identified patient population characteristics in 366 hospitals reporting HA-CDI rates. Of these, there were 19 (5%) long term acute care centers, 21 (6%) teaching hospitals, and 139 (38%) hospitals using PCR methods. Across all hospitals, the mean number of annual admissions was 10,385; mean number of licensed beds, 210; mean age, 50 years; and mean length of stay, 11.3 days. Overall, the mean HA-CDI incidence rate across all 366 hospitals was 8.4 cases per 10,000 patient-days (range 0-53.2). Table 1 shows predictors of HA-CDI rates from multivariate modeling. Conclusion: There are important facility level predictors of HA-CDI rates in CA hospitals, suggesting that adjustment for case mix and testing method is important for inter-hospital comparison of CDI rates. Further research is needed to better understand modifiable risks for prevention purposes.
    IDWeek 2012 Meeting of the Infectious Diseases Society of America; 10/2012
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    ABSTRACT: Harboring sensitive strains may prevent acquisition of resistant pathogens by competing for colonization of ecological niches. Competition may be relevant to decolonization strategies that eliminate sensitive strains and may predispose to acquiring resistant strains in high-endemic settings. We evaluated the impact of colonization with methicillin-sensitive Staphylococcus aureus (MSSA) and vancomycin-sensitive enterococci (VSE) on acquisition of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE), respectively, when controlling for other risk factors. We conducted a nested case-control study of patients admitted to eight ICUs performing admission and weekly bilateral nares and rectal screening for MRSA and VRE, respectively. Analyses were identical for both pathogens. For MRSA, patients were identified who had a negative nares screen and no prior history of MRSA. We evaluated predictors of MRSA acquisition, defined as a subsequent MRSA-positive clinical or screening culture, compared to those with a subsequent MRSA-negative nares screen within the same hospitalization. Medical records were reviewed for the presence of MSSA on the initial MRSA-negative nares screen, demographic and comorbidity information, medical devices, procedures, antibiotic utilization, and daily exposure to MRSA-positive patients in the same ward. Generalized linear mixed models were used to assess predictors of acquisition. In multivariate models, MSSA carriage protected against subsequent MRSA acquisition (OR = 0.52, CI: 0.29, 0.95), even when controlling for other risk factors. MRSA predictors included intubation (OR = 4.65, CI: 1.77, 12.26), fluoroquinolone exposure (OR = 1.91, CI: 1.20, 3.04), and increased time from ICU admission to initial negative swab (OR = 15.59, CI: 8.40, 28.94). In contrast, VSE carriage did not protect against VRE acquisition (OR = 1.37, CI: 0.54, 3.48), whereas hemodialysis (OR = 2.60, CI: 1.19, 5.70), low albumin (OR = 2.07, CI: 1.12, 3.83), fluoroquinolones (OR = 1.90, CI: 1.14, 3.17), third-generation cephalosporins (OR = 1.89, CI: 1.15, 3.10), and increased time from ICU admission to initial negative swab (OR = 15.13, CI: 7.86, 29.14) were predictive. MSSA carriage reduced the odds of MRSA acquisition by 50% in ICUs. In contrast, VSE colonization was not protective against VRE acquisition. Studies are needed to evaluate whether decolonization of MSSA ICU carriers increases the risk of acquiring MRSA when discharging patients to high-endemic MRSA healthcare settings. This may be particularly important for populations in whom MRSA infection may be more frequent and severe than MSSA infections, such as ICU patients.
    Critical care (London, England) 09/2011; 15(5):R210. · 4.72 Impact Factor
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    ABSTRACT: To evaluate whether longitudinal insurer claims data allow reliable identification of elevated hospital surgical site infection (SSI) rates. We conducted a retrospective cohort study of Medicare beneficiaries who underwent coronary artery bypass grafting (CABG) in US hospitals performing at least 80 procedures in 2005. Hospitals were assigned to deciles by using case mix-adjusted probabilities of having an SSI-related inpatient or outpatient claim code within 60 days of surgery. We then reviewed medical records of randomly selected patients to assess whether chart-confirmed SSI risk was higher in hospitals in the worst deciles compared with the best deciles. Fee-for-service Medicare beneficiaries who underwent CABG in these hospitals in 2005. We evaluated 114,673 patients who underwent CABG in 671 hospitals. In the best decile, 7.8% (958/12,307) of patients had an SSI-related code, compared with 24.8% (2,747/11,068) in the worst decile ([Formula: see text]). Medical record review confirmed SSI in 40% (388/980) of those with SSI-related codes. In the best decile, the chart-confirmed annual SSI rate was 3.2%, compared with 9.4% in the worst decile, with an adjusted odds ratio of SSI of 2.7 (confidence interval, 2.2-3.3; [Formula: see text]) for CABG performed in a worst-decile hospital compared with a best-decile hospital. Claims data can identify groups of hospitals with unusually high or low post-CABG SSI rates. Assessment of claims is more reproducible and efficient than current surveillance methods. This example of secondary use of routinely recorded electronic health information to assess quality of care can identify hospitals that may benefit from prevention programs.
    Infection Control and Hospital Epidemiology 08/2011; 32(8):775-83. · 4.02 Impact Factor
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    ABSTRACT: Admission to intensive care unit rooms previously occupied by carriers of methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant enteroccoci (VRE) had been found to confer a 40% increased risk of acquisition, presumably through environmental contamination. Subsequently, a cleaning intervention was shown to reduce MRSA and VRE room contamination. We now evaluate the effect of this intervention on the risk of acquiring MRSA and VRE from prior room occupants. We conducted a retrospective cohort study of patients admitted to 10 intensive care units at a 750-bed academic medical center during the enhanced cleaning intervention (from September 1, 2006, through April 30, 2008; n = 9449) vs baseline (from September 1, 2003, through April 30, 2005; n = 8203) periods. The intervention consisted of targeted feedback using a black-light marker, cleaning cloths saturated with disinfectant via bucket immersion, and increased education regarding the importance of repeated bucket immersion during cleaning. Intensive care units included medical, cardiac, burn/trauma, general surgery, cardiac surgery, thoracic surgery, and neurosurgery units. We calculated the number of room stays involving the potential for MRSA and VRE acquisition and then assessed the frequency at which eligible patients were exposed to rooms in which the prior occupants had MRSA-positive or VRE-positive status. Acquisition of MRSA and VRE was lowered from 3.0% to 1.5% for MRSA and from 3.0% to 2.2% for VRE (P < .001 for both). Patients in rooms previously occupied by MRSA carriers had an increased risk of acquisition during the baseline (3.9% vs 2.9%, P = .03) but not the intervention (1.5% vs 1.5%, P = .79) period. In contrast, patients in rooms previously occupied by VRE carriers had an increased risk of acquisition during the baseline (4.5% vs 2.8%, P = .001) and intervention (3.5% vs 2.0%, P < .001) periods. Enhanced intensive care unit cleaning using the intervention methods may reduce MRSA and VRE transmission. It may also eliminate the risk of MRSA acquisition due to an MRSA-positive prior room occupant.
    Archives of internal medicine 03/2011; 171(6):491-4. · 11.46 Impact Factor
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    ABSTRACT: Many studies have evaluated methicillin-resistant Staphylococcus aureus (MRSA) infections during single hospitalizations and subsequent readmissions to the same institution. None have assessed the comprehensive burden of MRSA infection in the period after hospital discharge while accounting for healthcare utilization across institutions. We conducted a retrospective cohort study of adult patients insured by Harvard Pilgrim Health Care who were newly-detected to harbor MRSA between January 1991 and December 2003 at a tertiary care medical center. We evaluated all MRSA-attributable infections associated with hospitalization in the year following new detection, regardless of hospital location. Data were collected on comorbidities, healthcare utilization, mortality and MRSA outcomes. Of 591 newly-detected MRSA carriers, 23% were colonized and 77% were infected upon detection. In the year following detection, 196 (33%) patients developed 317 discrete and unrelated MRSA infections. The most common infections were pneumonia (34%), soft tissue (27%), and primary bloodstream (18%) infections. Infections occurred a median of 56 days post-detection. Of all infections, 26% involved bacteremia, and 17% caused MRSA-attributable death. During the admission where MRSA was newly-detected, 14% (82/576) developed subsequent infection. Of those surviving to discharge, 24% (114/482) developed post-discharge infections in the year following detection. Half (99/185, 54%) of post-discharge infections caused readmission, and most (104/185, 55%) occurred over 90 days post-discharge. In high-risk tertiary care patients, newly-detected MRSA carriage confers large risks of infection and substantial attributable mortality in the year following acquisition. Most infections occur post-discharge, and 18% of infections associated with readmission occurred in hospitals other than the one where MRSA was newly-detected. Despite gains in reducing MRSA infections during hospitalization, the risk of MRSA infection among critically and chronically ill carriers persists after discharge and warrants targeted prevention strategies.
    PLoS ONE 01/2011; 6(9):e24340. · 3.53 Impact Factor
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    Rupak Datta, Susan S Huang
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    ABSTRACT: Postdischarge risks of vancomycin-resistant Enterococcus (VRE) infection among carriers are unknown. We conducted a retrospective cohort study of 199 patients newly detected as VRE carriers. Fifteen patients (8%) developed 27 VRE infections in the 18 months after detection. Among 10 postdischarge infections, 2 involved bacteremia and 3 resulted in readmission.
    Infection Control and Hospital Epidemiology 10/2010; 31(12):1290-3. · 4.02 Impact Factor
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    ABSTRACT: New prophylactic approaches are needed to control infection with the Gram-positive bacterium Staphylococcus aureus, which is a major cause of nosocomial and community-acquired infections. To develop these, greater understanding of protective immunity against S. aureus infection is needed. Human immunity to extracellular Gram-positive bacterial pathogens is primarily mediated by opsonic killing (OPK) via antibodies specific for surface polysaccharides. S. aureus expresses two such antigens, capsular polysaccharide (CP) and poly-N-acetyl glucosamine (PNAG). Here, we have shown that immunization-induced polyclonal animal antisera and monoclonal antibodies specific for either CP or PNAG antigens have excellent in vitro OPK activity in human blood but that when mixed together they show potent interference in OPK activity. In addition, reductions in antibody binding to the bacterial surface, complement deposition, and passive protection were seen in two mouse models of S. aureus infection. Electron microscopy, isothermal calorimetry, and surface plasmon resonance indicated that antibodies to CP and PNAG bound together via an apparent idiotype-anti-idiotype interaction. This interaction was also found in sera from humans with S. aureus bacteremia. These findings suggest that the lack of effective immunity to S. aureus infections in humans could be due, in part, to interference in OPK when antibodies to CP and PNAG antigens are both present. This information could be used to better design S. aureus vaccine components.
    The Journal of clinical investigation 09/2010; 120(9):3220-33. · 15.39 Impact Factor
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    Rupak Datta, Susan S Huang
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    ABSTRACT: 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. 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). 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. 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.
    Clinical Infectious Diseases 08/2008; 47(2):176-81. · 9.37 Impact Factor
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    ABSTRACT: Invasive disease following methicillin-resistant Staphylococcus aureus (MRSA) detection is common, regardless of whether initial detection involves colonization or infection. We assessed the genetic relatedness of isolates obtained > or =2 weeks apart representing either repeated infections or colonization-infection sets to determine if infections are likely to be caused by previously harbored strains. We found that MRSA infection following initial colonization or infection is caused by the same strain in most cases, suggesting that a single successful attempt at decolonization may prevent the majority of later infection.
    Clinical Infectious Diseases 05/2008; 46(8):1241-7. · 9.37 Impact Factor
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    ABSTRACT: 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. 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. 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. 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.
    Clinical Infectious Diseases 11/2006; 43(8):971-8. · 9.37 Impact Factor
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    ABSTRACT: Environmental contamination with methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) occurs during the care of patients harboring these organisms and may increase the risk of transmission to subsequent room occupants. Twenty-month retrospective cohort study of patients admitted to 8 intensive care units performing routine admission and weekly screening for MRSA and VRE. We assessed the relative odds of acquisition among patients admitted to rooms in which the most recent occupants were MRSA positive or VRE positive, compared with patients admitted to other rooms. Of 11 528 intensive care unit room stays, 10 151 occupants were eligible to acquire MRSA, and 10 349 were eligible to acquire VRE. Among patients whose prior room occupant was MRSA positive, 3.9% acquired MRSA, compared with 2.9% of patients whose prior room occupant was MRSA negative (adjusted odds ratio, 1.4; P = .04). VRE, Among patients whose prior room occupant was VRE positive, these values were 4.5% and 2.8% respectively (adjusted odds ratio, 1.4; P = .02). These excess risks accounted for 5.1% of all incident MRSA cases and 6.8% of all incident VRE cases, with a population attributable risk among exposed patients of less than 2% for either organism. Acquisition was significantly associated with longer post-intensive care unit length of stay. Admission to a room previously occupied by an MRSA-positive patient or a VRE-positive patient significantly increased the odds of acquisition for MRSA and VRE. However, this route of transmission was a minor contributor to overall transmission. The effect of current cleaning practices in reducing the risk to the observed levels and the potential for further reduction are unknown.
    Archives of Internal Medicine 11/2006; 166(18):1945-51. · 11.46 Impact Factor

Publication Stats

525 Citations
98.94 Total Impact Points

Institutions

  • 2008–2014
    • University of California, Irvine
      • Division of Infectious Diseases
      Irvine, California, United States
  • 2008–2011
    • Harvard Medical School
      • Department of Population Medicine
      Boston, MA, United States
  • 2006
    • Brigham and Women's Hospital
      • Department of Medicine
      Boston, MA, United States