Susan Whittier

Columbia University, New York, New York, United States

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Publications (68)251.9 Total impact

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    ABSTRACT: Despite the growing importance of carbapenem-resistant Klebsiella pneumoniae (CRKP), the clonal relationships between CRKP and antibiotic-susceptible isolates remain unclear. We compared the genetic diversity and clinical features of CRKP, 3rd and/or 4th generation cephalosporin-resistant (Ceph-R), and susceptible K. pneumoniae causing bloodstream infections at a tertiary care hospital in New York City between January 2012 and July 2013. Drug susceptibilities were determined by Vitek2. Isolates underwent multi-locus sequence typing and PCR-sequencing of the wzi and blaKPC genes. Clinical and microbiologic data were extracted from patient records and correlated with molecular data. Among 223 patients, we identified 272 isolates. Of these, 194 were susceptible, 30 Ceph-R, and 48 CRKP and belonged to 144 sequence types (STs). Susceptible (127 STs) and Ceph-R (20 STs) isolates were highly diverse. ST258 dominated CRKP strains (12 STs; 63% ST258). There was minimal overlap in STs between resistance groups. BlaKPC-3 (30%) was restricted to ST258/wzi154, whereas blaKPC-2 (70%) included several wzi alleles. CRKP infections occurred more frequently in solid organ transplant (31%) and dialysis patients (17%). Mortality was overall high (28%) and highest in CRKP-infected patients (59%). In multivariable analyses, advanced age, comorbidities and the severity of disease were significant predictors of 30-day mortality whereas the K. pneumoniae susceptibility phenotype was not. Amongst CRKP infections we observed a borderline significant association to increased mortality with ST258 and the wzi154 allele. Although the clonal spread of ST258 continues to contribute substantially to the dissemination of CRKP, non-ST258 strains appear to be evolving. Further investigations into the mechanisms promoting CRKP diversification and the impact of clonal background on outcomes are warranted. Copyright © 2015, American Society for Microbiology. All Rights Reserved.
    Journal of clinical microbiology 04/2015; DOI:10.1128/JCM.03455-14 · 4.23 Impact Factor
  • Gastroenterology 04/2015; 148(4):S-619. DOI:10.1016/S0016-5085(15)32089-8 · 13.93 Impact Factor
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    ABSTRACT: The high sensitivity of PCR assays for the detection of Clostridium difficile infection (CDI) has greatly reduced the need for repeat testing after a negative result. Nevertheless, a small subset of patients do test positive within 7 days of a negative test. The aim of this study is to evaluate the clinical characteristics of these patients to determine when repeat testing may be appropriate. The results of all Xpert C. difficile PCR (Cepheid, Sunnyvale CA) tests performed in the clinical microbiology laboratory at NewYork-Presbyterian Hospital, Columbia University Medical Center (NYPH/CUMC) from May 1, 2011 through September 6, 2013 were reviewed. A retrospective case-control study was performed comparing patients who tested positive within 7 days of a negative test result to a random selection of 50 controls who tested negative within 7 days of a negative test result. During the study period a total of 14,875 tests were performed, of which 1066 were repeat tests (7.2%). 11 of these repeat tests were positive (1.0%). The only risk factor independently associated with repeat testing positive was history of a prior CDI (OR: 19.6 [95% CI: 4.0 - 19.5], p < 0.001). Patients who test positive for C. difficile by PCR within 7 days of a negative test are more likely to have a history of CDI than patients who repeat test negative. This finding may be due to the high rate of disease relapse or the increased likelihood of empiric therapy leading to false negative results in these patients.
    Journal of Clinical Microbiology 08/2014; 52(11). DOI:10.1128/JCM.01659-14 · 4.23 Impact Factor
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    S. Whittier, P. Della-Latta
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    ABSTRACT: Extremely drug-resistant gram-negative bacilli (XDR-GNB) increasingly cause health care-associated infections (HAIs) in intensive care units (ICUs). A matched case-control (1:2) study was conducted from February 2007 to January 2010 in 16 ICUs. Case and control subjects had HAIs caused by GNB susceptible to ≤ 1 antibiotic versus ≥ 2 antibiotics, respectively. Logistic and Cox proportional hazards regression assessed risk factors for HAIs and predictors of mortality, respectively. Overall, 103 case and 195 control subjects were enrolled. An immunocompromised state (odds ratio [OR], 1.55; P = .047) and exposure to amikacin (OR, 13.81; P < .001), levofloxacin (OR, 2.05; P = .005), or trimethoprim-sulfamethoxazole (OR, 3.42; P = .009) were factors associated with XDR-GNB HAIs. Multiple factors in both case and control subjects significantly predicted increased mortality at different time intervals after HAI diagnosis. At 7 days, liver disease (hazard ratio [HR], 5.52), immunocompromised state (HR, 3.41), and bloodstream infection (HR, 2.55) predicted mortality; at 15 days, age (HR, 1.02 per year increase), liver disease (HR, 3.34), and immunocompromised state (HR, 2.03) predicted mortality; and, at 30 days, age (HR, 1.02 per 1-year increase), liver disease (HR, 3.34), immunocompromised state (HR, 2.03), and hospitalization in a medical ICU (HR, 1.85) predicted mortality. HAIs caused by XDR-GNB were associated with potentially modifiable factors. Age, liver disease, and immunocompromised state, but not XDR-GNB HAIs, were associated with mortality.
    American journal of infection control 04/2014; 42(6). DOI:10.1016/j.ajic.2014.01.027 · 2.33 Impact Factor
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    ABSTRACT: Background: Diagnosis of ventriculostomy-related infections (VRIs) can be challenging and is based upon interpretation of clinical and cerebrospinal fluid (CSF) parameters. We developed and validated a multiplex MassTag polymerase chain reaction (PCR) assay for the rapid diagnosis of VRIs utilizing organism-specific primers. Methods: A 13-plex MassTag PCR panel was developed targeting the most common pathogens causing VRIs at our institution, as identified in a retrospective review of culture-positive ventricular device (VD) CSF specimens between 2001-2006. The panel was optimized using cloned template standards and spiked samples. The level of detection ranged from 102-104 organisms per mL. The MassTag panel was evaluated on serially collected CSF specimens sent to the clinical microbiology laboratory. A retrospective review was performed to determine CSF and clinical parameters. VD patients were grouped into (1) definite VRI, (2) possible VRI, or (3) no VRI; while non-VD patients were grouped into (1) definite central nervous system (CNS) infection, (2) possible CNS infection, or (3) no CNS infection. Contamination or colonization was defined as organism detection in a patient with no VRI or no CNS infection. Results: CSF from 128 subjects were analyzed: 49 with a VD (median age 43 years; interquartile range [IQR] 30-62 years; males 49%), and 79 without a VD (median age 45 years; IQR 21-59 years; males 49%). Among subjects with a definite VRI or CNS infection due to a pathogen on the MassTag panel, the pathogen was identified in all cases (9/9). Among subjects with a possible VRI, the MassTag panel detected >1 pathogen in 33% of samples. Among subjects with no VRI or no VD and no CNS infection, an organism, mostly gram-positive bacteria was detected in 32% and 11%, respectively, representing either contamination or VD colonization. Conclusion: The VRI MassTag panel performed well in definite VRI and CNS infection and detected potential pathogens in possible VRI cases. However, the false positive rate with Staphylococcus and Enterococcus species necessitates the need for further confirmatory testing if these organisms are detected. Nonetheless, the negative predictive value for gram-negative bacteria suggests that empiric antibiotics can be narrowed if no gram-negative bacteria are detected.
    IDWeek 2013 Meeting of the Infectious Diseases Society of America; 10/2013
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    ABSTRACT: Disease caused by Powassan virus (POWV), a tick-borne flavivirus, ranges from asymptomatic to severe neurologic compromise and death. Two cases of POWV meningoencephalitis in New York, USA, highlight diagnostic techniques, neurologic outcomes, and the effect of POWV on communities to which it is endemic.
    Emerging Infectious Diseases 09/2013; 19(9). DOI:10.3201/eid1909.121846 · 7.33 Impact Factor
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    ABSTRACT: Infections with antibiotic resistant organisms (AROs) are an important source of morbidity and mortality among infants hospitalized in the neonatal intensive care unit (NICU). To identify potential reservoirs of AROs in the NICU, active surveillance strategies have been adopted by many NICUs to detect infants colonized with AROs. However, the yield, risks, benefits, and costs of different strategies have not been fully evaluated. We conducted a retrospective study in two level III NICUs from 2004-2010 to investigate the yield of surveillance cultures obtained from infants transferred to the NICU from other hospitals. Cultures were processed for methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), and antibiotic resistant gram negative rods (AR-GNR). Risk factors, selected outcomes, and laboratory costs associated with ARO-colonization were assessed. Among 1751 infants studied, the rate of colonization for MRSA, VRE, and AR-GNR was 3%, 1.7%, and 1% respectively. Age at transfer was the strongest predictor of ARO colonization; infants transferred at ≥ 7 days of life had 5.8 increased odds of ARO colonization compared with infants < 7 days of age. Transferred infants who were colonized had similar rates of mortality, ARO infection, and duration of hospitalization compared to those who were not colonized. The laboratory cost of surveillance cultures during the study period was $58,425. The rate of colonization with AROs at transfer was low particularly in infants < 7 days old. Future studies should examine the safety of targeted surveillance strategies focused on older infants.
    The Pediatric Infectious Disease Journal 06/2013; 32(12). DOI:10.1097/INF.0b013e3182a1d77f · 3.14 Impact Factor
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    ABSTRACT: Carbapenems are increasingly needed to treat infections caused by drug-resistant gram-negative bacilli (GNB), but carbapenem resistance is increasing. We evaluated the activity of doripenem by broth microdilution against 96 extensively drug-resistant (XDR) Acinetobacter baumannii and Klebsiella pneumoniae isolates from patients with hospital-associated infections. All isolates were non-susceptible to doripenem, but ≥1 doripenem combination demonstrated synergy (fractional inhibitory concentration index: ≤0.5 for 2 agents, ≤0.75 for 3 agents) against 7 (15%) A. baumannii and 23 (48%) K. pneumoniae isolates; doripenem with rifampin and/or polymyxin B were most active. As doripenem has unique potential for use in prolonged infusions, suggested pharmacodynamic (PD) breakpoints range from 2-8 μg/mL; synergistic activity was found for higher proportions of XDR-GNB at higher PD breakpoints with doripenem with amikacin or with rifampin. The clinical utility of these observations requires further study, as treatment options for XDR-GNB infections are limited.
    Diagnostic microbiology and infectious disease 04/2013; 76(3). DOI:10.1016/j.diagmicrobio.2013.03.014 · 2.57 Impact Factor
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    ABSTRACT: Bordetella holmesii is an emerging opportunistic pathogen that causes respiratory disease in healthy individuals and invasive infections among patients lacking splenic function. We used 16S rRNA gene analysis to confirm B. holmesii as the cause of bacteremia in a child with sickle cell disease. Semiconductor-based draft genome sequencing provided insight into B. holmesii phylogeny and potential virulence mechanisms and also identified a toluene-4-monoxygenase locus unique among bordetellae.
    03/2013; 67(2):132-5. DOI:10.1111/2049-632X.12028
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    ABSTRACT: Streptococcus intermedius is a human pathogen with a propensity for abscess formation. We report a high-quality draft genome sequence of S. intermedius strain BA1, an isolate from a human epidural abscess. This sequence provides insight into the biology of S. intermedius and will aid investigations of pathogenicity.
    Genome Announcements 01/2013; 1(1). DOI:10.1128/genomeA.00117-12
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    ABSTRACT: While much is known about the geographic distribution of different clonal types of methicillin-resistant Staphylococcus aureus (MRSA), few studies have assessed the molecular epidemiology of methicillin-susceptible S. aureus (MSSA), despite its continued clinical importance. In each US Census region, reference laboratories collected successive MSSA isolates from patients with invasive or superficial staphylococcal infections for use in the Tigecycline Evaluation and Surveillance Trial. All isolates from 2004-5 and 2009-10 underwent antimicrobial susceptibility testing and characterization of their staphylococcal protein A (spa) type. Of the 708 isolates analyzed, 274 spa types were identified and divided into 15 genetic clusters. The most common clones were spa t002 (n=63, 8.9%) and t008 (n=56, 7.9%). While the distribution of predominant spa types was not different by US Census region or time period, spa t008 was nearly twice as common in community skin and soft tissue infections compared with nosocomial bloodstream infections (11.1% v. 5.6%, respectively, p=.008). Despite such differences, both community and nosocomial settings had diverse staphylococcal clonal types representing all major spa clusters. In contrast to MRSA, MSSA infectious isolates show wide genetic diversity without clear geographical or temporal clustering. Notably, the prevalent MSSA strains (spa t002 and spa t008) are analogous to the predominant MRSA clones, further demonstrating the importance of these lineages.
    Journal of clinical microbiology 01/2013; 51(3). DOI:10.1128/JCM.00923-12 · 4.23 Impact Factor
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    ABSTRACT: Background: Bacterial vaginosis (BV) is associated with an increased risk of preterm birth (PTB) and acquisition of sexually transmitted infections. Currently, the primary clinical tool for BV diagnosis is the Amsel criteria. However, not all women with BV as determined by the "gold-standard" (Nugent score of Gram stained slides) are detected by Amsel criteria. Therefore, we investigated the characteristics of women with BV by Nugent score who were negative by Amsel criteria (A-N+). Methods: The BV-IDEAS (Bacterial Vaginosis: Improved Diagnosis by ELISA and Sequencing) cross-sectional study enrolls non-pregnant women from a racially/ethnically diverse urban clinic population to evaluate a new diagnostic test for BV and to elucidate BV risk factors. All data and clinical samples were collected during routine gynecologic visits. Presence/absence of BV by Amsel criteria and Nugent score were available for all women. Sociodemographic, medical, and behavioral characteristics of women were determined by interviewer-administered questionnaires. White and races other than black or Hispanic were combined due to small sample sizes. Chi-squared test and Fisher’s exact test were used to evaluate characteristics associated with A-N+ status. Results: Of the first 217 women enrolled in our study, 78 (36%) had Nugent score 7-10, indicating BV, and these 78 women were used in this analysis. There was a trend toward white/other women being more likely to be A-N+ compared with black women (p=0.058). Women who did not report vaginal discharge (p=0.007) or odor (p=0.024) were more likely to be A-N+. White/other women drove this association. Among white/other A-N+ women, none reported discharge or odor (p-values undefined due to zero row counts). Conclusion: While current treatments for BV have been unsuccessful in preventing PTB and other adverse sequelae, we are hopeful that future strategies will prove more effective. Reliance on Amsel criteria for the diagnosis of BV may leave some cases undetected, suggesting a need for improved classification and diagnostic strategies.
    IDWeek 2012 Meeting of the Infectious Diseases Society of America; 10/2012
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    ABSTRACT: Background: Infants hospitalized in the neonatal ICU (NICU) are at great risk of acquiring antimicrobial-resistant organisms. Predictors of endemic infant colonization with methicillin-resistant Staphylococcus aureus (MRSA) at discharge have not been studied. Methods: From May 2009 to September 2011, 1,105 infants in 4 level-III NICUs with ≥14 hospital-days had surveillance cultures of the nares and skin sites (periumbilical, axilla, and groin) obtained at NICU discharge. Swabs were processed in a central laboratory according to Clinical Laboratory and Standards Institute (CLSI) guidelines, and colonization was defined as isolation of MRSA from ≥1 swab. Demographic and clinical data were used to determine predictors of colonization. Variables found significant (P<0.2) on unadjusted analysis were entered into a generalized estimating equation with study site as a design variable. Results: Overall, 4% (range per site: 3-6%) of infants were colonized with MRSA at discharge, and the colonization rate ranged from 0.7-1.2 infants/1,000 patient-days. In all, 47 infants had 63 isolates detected: 18 (38%) nares only, 13 (28%) skin only, and 16 (34%) both sites. Only 8 infants had MRSA infections; MRSA infection was more common among infants colonized at discharge than among those who were not colonized (8.5% vs. 0.4%, respectively, P<0.01). In an adjusted multivariable model, only surgery was associated with MRSA colonization (OR: 1.90 95%CI: 1.23, 2.95). Conclusion: In this study, few infants had endemic infection or colonization with MRSA, but surveillance cultures of both nares and skin sites improved detection of MRSA colonization. Surgery increased the odds of infant colonization with MRSA at NICU discharge, which suggests that MRSA acquisition may occur when infants leave the NICU for surgical procedures or during post-surgical care. Future studies should continue to delineate routes of MRSA acquisition and the attack rate for infection following colonization.
    IDWeek 2012 Meeting of the Infectious Diseases Society of America; 10/2012
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    ABSTRACT: Background: Empiric and targeted antimicrobial therapy for gram-negative bacilli (GNB) is very common in the neonatal ICU (NICU). We hypothesized that prior antimicrobial treatment would be associated with infant colonization with antimicrobial resistant (AMR)-GNB at NICU discharge. Methods: From May 2009 to September 2011, 1,105 infants in 4 level-III NICUs with ≥14 hospital-days had rectal surveillance cultures obtained at NICU discharge. Swabs were processed in a central laboratory according to Clinical Laboratory and Standards Institute (CLSI) guidelines. GNB isolates were considered AMR if non-susceptible to gentamicin, ceftriaxone, and/or a carbapenem agent (2011 CLSI breakpoints). Demographic and clinical data, including days of specific antimicrobial treatment, were used to determine predictors of colonization. Variables found significant (P<0.2) on unadjusted analysis were entered into a generalized estimating equation with study site as a design variable. Results: Overall, 8% of infants harbored ≥1 AMR-GNB at discharge: 4% (n=47), 4% (n=42), and 2% (n=24) were colonized with ceftriaxone-, gentamicin-, and carbapenem-resistant GNB, respectively. Rates of colonization per site ranged from 0.3-6% or 0.1-1.2 infants/1,000 patient-days. Infants colonized with gentamicin-resistant GNB were more likely to have carbapenem, cephalosporin, or vancomycin treatment; colonization odds were 3.03 times higher (95%CI: 2.27, 4.03) with ≥4 carbapenem days, 1.62 times higher (95%CI: 1.12, 2.33) with ≥14 days of antimicrobial treatment. Infants colonized with ceftriaxone-resistant GNB had greater exposure to beta-lactams; colonization odds for females were 1.81 times higher (95%CI: 1.32, 2.50), but antimicrobial treatment was not an independent risk factor. Infants colonized with carbapenem-resistant GNB were less likely to have surgery or increased gestational age; both factors were protective in multivariable analysis. Conclusion: Prolonged antimicrobial treatment, particularly with carbapenems, predicted gentamicin-resistant GNB colonization, but antimicrobial treatment was not associated with colonization by other AMR-GNB at NICU discharge. Future studies should examine duration of colonization and patient-to-patient transmission from colonized infants.
    IDWeek 2012 Meeting of the Infectious Diseases Society of America; 10/2012
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    ABSTRACT: Background Multiple studies have been done on adult men who have sex with men (MSM), but no studies have shown the rates of extragenital site sexually transmitted infections (STIs) among HIV positive young men who have sex with men (YMSM). The objective of this study was to document the rates of extragenital Neisseria gonorrhoeae (GC) and Chlamydia trachomatis (CT) infection among HIV positive YMSM while conducting a validity study for the use of nucleic acid amplified tests (NAATs), to detect extragenital GC and CT.Methods Behaviorally infected HIV positive YMSM were enrolled in this study from one urban adolescent HIV clinic, and were screened for urine and extragenital site GC and CT over a 2 year period. Samples from these sites (pharyngeal and rectal) were tested for GC and CT using both traditional culture media and NAAT technology. Urine was tested using only NAAT.ResultsOf 67 screenings, 36% (n = 24) yielded at least one positive, and 69% of participants (18/26) had at least one positive GC or CT test result during the study period. Of those with at least one positive result, 89% (16/18) had at least one extragenital site infection. Urine testing was positive in 11% (2/18) of those with a corresponding extragenital site infection. None of the extragenital CT infections detected by NAATs were detected by culture, and only 38% (5/13) of the extragenital GC infections detected by NAATs were detected by culture.Conclusions Use of NAATs for extragenital STI screening yielded more confirmed positive results than did traditional cultures. By use of NAATs, the majority of routinely screened HIV positive YMSM in this sample was found to have an STI at an extragenital site.
    American journal of men's health 06/2012; 9(2):89–93. DOI:10.1016/j.jomh.2012.02.002 · 1.15 Impact Factor
  • American Journal of Infection Control 06/2012; 40(5):e168. DOI:10.1016/j.ajic.2012.04.297 · 2.33 Impact Factor
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    ABSTRACT: Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacteriaceae are endemic in New York City hospitals and have been associated with serious infections globally. A real-time polymerase chain reaction (RT-PCR) assay was developed to detect carbapenem resistance attributable to KPC from blood culture bottles positive for gram-negative bacilli. Culture confirmation of carbapenemase production included automated imipenem and meropenem susceptibility testing and ertapenem susceptibility testing by disk-diffusion. A total of 323 Enterobacteriaceae isolates were tested, of which 8.7% (n = 28) demonstrated carbapenem-resistance by automated and manual susceptibility testing methods or by RT-PCR. The sensitivity, specificity, and positive and negative predictive values of the RT-PCR assay when compared with the automated method were 92.9%, 99.3%, 92.9%, and 99.3%, respectively, and 96.4%, 99.7%, 96.4%, and 99.7%, respectively, when compared with the ertapenem disk-diffusion method. RT-PCR is a rapid and reliable means of detecting carbapenem resistance due to KPC-plasmids in Enterobacteriaceae directly from blood culture bottles.
    American Journal of Clinical Pathology 04/2012; 137(4):627-32. DOI:10.1309/AJCP9SNHJG2QGLWU · 3.01 Impact Factor
  • Aesthetic Surgery Journal 03/2012; 32(3):354-354. DOI:10.1177/1090820X12436840 · 2.03 Impact Factor
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    ABSTRACT: Staphylococcus aureus infections are increasing among pregnant and postpartum women and neonates, but risk factors for S. aureus colonization in pregnancy and the association between maternal colonization and infant infections are not well defined. We sought to identify risk factors for maternal S. aureus rectovaginal colonization and assess colonization as a risk factor for infections among mothers and infants. We conducted a retrospective cohort study of pregnant women and their infants. Demographic and clinical data, including S. aureus infections that occurred in mothers from 3 months before to 3 months after delivery and in infants during the first 3 months of life, were extracted from electronic medical records. Predictors for maternal S. aureus rectovaginal colonization were assessed through multivariable logistic regression analysis. The cohort included 2702 women and 2789 infants. The prevalence of maternal rectovaginal colonization with methicillin-susceptible S. aureus and methicillin-resistant S. aureus (MRSA) was 13% and 0.7%. Independent predictors of colonization included multigravidity, human immunodeficiency virus seropositivity, and group B Streptococcus colonization. S. aureus colonization was associated with an increased risk of infection in mothers (odds ratio [OR], 3.5; 95% confidence interval [CI], 1.4-8.8) but not in their infants (OR, 1.9; 95% CI, .6-5.6). The frequency of S. aureus infections was 0.8% in mothers and 0.7% in infants. S. aureus rectovaginal colonization was associated with an increased risk of infections in women but not in their infants. The frequency of MRSA infections was low. These data suggest that routine MRSA screening of pregnant women may not be indicated.
    03/2012; 1(1):7-15. DOI:10.1093/jpids/pis001

Publication Stats

1k Citations
251.90 Total Impact Points

Institutions

  • 1998–2015
    • Columbia University
      • • Department of Pathology & Cell Biology
      • • College of Physicians and Surgeons
      • • Department of Pediatrics
      New York, New York, United States
  • 1998–2013
    • New York Presbyterian Hospital
      • • Department of Pathology
      • • Department of Pediatrics
      New York City, New York, United States
  • 2011
    • CUNY Graduate Center
      New York City, New York, United States
  • 2007
    • Gracie Square Hospital, New York, NY
      New York City, New York, United States
  • 1999
    • University of Washington Seattle
      • Department of Pediatrics
      Seattle, Washington, United States
  • 1995
    • Montefiore Medical Center
      • Department of Pathology
      New York, New York, United States
  • 1993–1995
    • University of North Carolina at Chapel Hill
      North Carolina, United States