E O Mason

Texas Children's Hospital, Houston, Texas, United States

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Publications (182)839.66 Total impact

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    ABSTRACT: Staphylococcus aureus bacteremia without a localizing source in children is not well described. We identified patients with a positive blood culture for S. aureus from an 11-year surveillance study. Thirty-six cases of primary bacteremia were identified accounting for 5.7% of bacteremias. Most patients had comorbidities (86.1%), most commonly immunosuppression (33.3%).
    The Pediatric Infectious Disease Journal 05/2014; 33(5):e132-4. · 3.57 Impact Factor
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    ABSTRACT: The widespread use of the 7-valent pneumococcal conjugate vaccine has been associated with epidemiological changes of mucosal and invasive pneumococcal disease. No study describes the impact of 13-valent pneumococcal conjugate vaccine (PCV13) on chronic sinusitis in children. We describe changes in epidemiology of S. pneumoniae chronic sinusitis after the introduction of PCV13 at Texas Children's Hospital (TCH). We identified patients <18 years with positive sinus culture for S. pneumoniae who underwent endoscopic sinus surgery due to chronic sinusitis from August 2008 to December 2013 at TCH. Isolates were serotyped by the capsular swelling method. Demographic and clinical information was collected retrospectively. The χ2 test and Fisher's exact test were used to analyze dichotomous variables. We identified 91 cases of chronic sinusitis with positive sinus culture for S. pneumoniae. Sixty-one (67%) isolates were non-PCV13 serotypes. PCV13 cases decreased 31% in the post-PCV13 period (p=0.003). Serotype 19A decreased 27% in the post-PCV13 period (p=0.007), but accounted for all the isolates with penicillin MIC ≥ 4µg/ml and ceftriaxone MIC ≥2 µg/ml. Serotypes 19A (38%) and 15C (17%) were the most common in the pre- and post-PCV13 periods, respectively. The most common organism co-isolated was Haemophilus influenzae (52%). Isolation of Prevotella spp. increased in the post-PCV13 period (p=0.02). S. pneumoniae continues to represent an important pathogen in chronic sinusitis in children < 5 years. After the introduction of PCV13, S. pneumoniae isolation declined in children with chronic sinusitis at TCH. We also observed a substantial reduction of PCV13 serotypes, predominantly serotype 19A.
    The Pediatric Infectious Disease Journal 04/2014; · 3.57 Impact Factor
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    ABSTRACT: Background: Topical antimicrobial and antiseptic agents are commonly used in the management of minor skin and soft tissue infections (SSTI). Resistance to mupirocin has been documented in S. aureus isolates causing SSTIs. Data are limited, however, on the prevalence of retapamulin resistance or tolerance to antiseptics. We sought to determine the prevalence of decreased susceptibility to retapamulin and mupirocin as well as the potential for decreased chlorhexidine susceptibility of S. aureus isolates from SSTIs in children.Methods: Two-hundred isolates from patients with a single SSTI and 200 isolates from patients with ≥3 previous episodes from the years 2010-2012 were selected from a S. aureus surveillance study. Screening for retapamulin resistance was performed by the macrobroth dilution method; mupirocin MICs were determined by E-test. PCR was performed for the presence of the smr gene associated with elevated MIC/MBCs to chlorhexidine.Results: Among the isolates screened, 38 isolates (9.5%) exhibited retapamulin resistance of which 22(57.9%) were MRSA. Two isolates (0.5%) displayed cross-resistance to retapamulin and linezolid. Thirty-nine isolates (9.8%) were found to have mupirocin resistance. smr-positive S. aureus accounted for 14% of isolates. The proportion of smr-positive organisms increased during the study (p=0.005).Conclusions: The prevalence of in vitro resistance to topical antimicrobials among S. aureus causing SSTI in healthy children in our community is almost 10%. Retapamulin resistance was associated with cross resistance to linezolid in 0.5% of isolates. In addition, there was an increase in the proportion of smr-positive isolates. Further research including clinical correlations with these findings is warranted.
    Antimicrobial Agents and Chemotherapy 03/2014; · 4.57 Impact Factor
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    ABSTRACT: Children with probable CA-SA skin and soft (SSI) or invasive infections were randomized to routine daily hygienic measures with or without "bleach baths" twice a week (Bleach) for 3 months. Within 12 months a medically attended recurrence occurred in 84/495 (17%) of Bleach vs. 103/492 (21%) of Control enrollees (p=0.15).
    Clinical Infectious Diseases 11/2013; · 9.37 Impact Factor
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    ABSTRACT: BACKGROUND:After licensure of the 7-valent pneumococcal conjugate vaccine (PCV7) in the United States in 2000, the incidence of pediatric pneumococcal meningitis decreased significantly. However, cases continue to occur. It is unknown whether meningitis due to PCV7 and non-PCV7 serotypes causes similar morbidity and mortality.METHODS:We performed a retrospective cohort study of laboratory-confirmed pneumococcal meningitis among Utah children from 1997 to 2010. We reviewed medical records and obtained clinical data during the acute illness and follow-up data on neurologic sequelae.RESULTS:Sixty-eight cases of meningitis were identified. PCV7 serotypes caused 64% of cases before and 25% of cases after licensure of PCV7 (P < .01). The age range was similar before and after PCV7 licensure (P = .5). The overall case fatality rate was 13% and was similar among cases caused by PCV7 and non-PCV7 serotypes (P = .7). Children with PCV7 serotypes were more likely to require mechanical ventilation (68% vs 34%; P < .01). Of all survivors, 63% had neurologic sequelae, and the proportion was similar after infection with PCV7 or non-PCV7 serotypes (P = .1). More than one-half (54%) of all children who developed pneumococcal meningitis in the PCV7 period were eligible for PCV7 and had not been immunized.CONCLUSIONS:Pneumococcal meningitis continues to be associated with high mortality and morbidity; death and neurologic sequelae are common with both PCV7 and non-PCV7 serotype meningitis. The substantial burden of this disease and continued cases among unimmunized children reinforce the need for more effective immunization strategies and continued surveillance in the era of PCV13.
    PEDIATRICS 08/2013; · 4.47 Impact Factor
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    ABSTRACT: CA-S. aureus (CA-MRSA in 57%) infections were reviewed in 179 infants (0-60 d) from June 2006-June 2011. CA-MSSA accounted for 16/44 (36%) in Year 1 up to 12/25 (48%) in Year 5 (P=0.08). Abscess/cellulitis infections were more likely (P=0.006) to be caused by CA-MRSA (67%) versus other manifestations of infections (46%). Among 160 isolates, 13% were clindamycin resistant and 63% were USA300.
    The Pediatric Infectious Disease Journal 08/2013; · 3.57 Impact Factor
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    ABSTRACT: There are limited data characterizing recurrent staphylococcal disease in children. We sought to define the clinical features and laboratory findings of children with recurrent community-associated (CA) S. aureus infections presenting to Texas Children's Hospital (TCH) in Houston, TX. Medical records of children with recurrent, culture-proven CA-S. aureus infections at TCH from 8/1/2001-7/29/2009 were reviewed, and antibiotic susceptibility patterns were obtained for all S. aureus isolates. 694 otherwise healthy patients presented to TCH with 2-7 episodes of CA-S. aureus infection, accounting for 1495 encounters, 823 hospitalizations, and 3337 inpatient days. In 90% of patients with ≤ 12 months separating their initial and recurrent infections, the methicillin susceptibility of the initial and recurrent isolates was the same, compared with 79% of patients with > 12 months separating their infections. The overall antibiotic susceptibility pattern did not change between isolates in 71% of otherwise healthy children compared with only 33% of children with eczema. 92% of otherwise healthy children had only recurrent SSTI; 8% had ≥ 1 non-SSTI. The location of SSTI's varied by age, with children ≤ 36 months of age being more likely to have ≥ 1 S. aureus infection located in the diaper area. Our study demonstrates that recurrent staphylococcal disease requiring emergency center or inpatient care is common, accounting for significant utilization of hospital resources. Children with recurrent staphylococcal infections are likely to have repeated infections from the same staphylococcal strain (by antibiotic susceptibility pattern), indicating that persistent colonization, frequent exposure to others who are chronically colonized, or environmental contamination is playing a role in recurrent disease. Finally, our study emphasizes the need for repeat cultures in children with recurrent disease, as 29% of healthy children and 67% of children with a predisposing risk factor (such as eczema) have a change in the antibiotic susceptibility pattern between S. aureus isolates.
    The Pediatric Infectious Disease Journal 07/2013; · 3.57 Impact Factor
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    ABSTRACT: BACKGROUND:Introduction of the heptavalent pneumococcal conjugate vaccine (PCV7) changed the epidemiology of invasive pneumococcal disease (IPD). We evaluated the changes that occurred after PCV7 introduction among Utah infants aged 1 to 90 days, too young to be fully immunized.METHODS:We identified children <18 years with culture-confirmed IPD from 1997-2010. We analyzed demographic, clinical, and serotype data for infants aged 1-90 days. The pre- and post-vaccine introduction periods spanned 1997-2000 and 2001-2010, respectively.RESULTS:Of 513 children with IPD, 36 were 1 to 90 days and accounted for 7% of IPD cases in both the pre- and post-vaccine introduction period. The pre-vaccine IPD incidence rate was 5.0 per 100 000 live births, and was unchanged in the post-vaccine introduction period. IPD caused by PCV7 serotypes decreased by 74% (from 2.2 to 0.58 per 100 000), whereas non-vaccine serotype IPD increased by 57% (from 2.8 to 4.4 per 100 000). Sixteen infants (44%) required intensive care, and 3 (8%) died. Bacteremia without focus (56%) and meningitis (44%) were the predominant syndromes in the pre- and post-vaccine introduction periods, respectively. In the post-vaccine introduction period, serotype 7F was the most common serotype among infants and was responsible for 50% of meningitis.CONCLUSIONS:The incidence of IPD in Utah infants aged 1 to 90 days caused by PCV7 serotypes decreased after PCV7 introduction, but overall incidence was unchanged. In the post-vaccine introduction period, serotype 7F predominated in this age group and was associated with meningitis.
    PEDIATRICS 06/2013; · 4.47 Impact Factor
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    ABSTRACT: BACKGROUND:: Invasive meningococcal infections can be devastating. Substantial endotoxemia releases mature and immature neutrophils. Endothelial margination of mature neutrophils may increase the immature to total neutrophil ratio. These changes have not been previously well-described in invasive meningococcal disease. METHODS:: Using 2001-2011 data from the US Multicenter Meningococcal Surveillance Study, the diagnostic sensitivity and clinical correlates of white blood cell count (WBC), absolute neutrophil count (ANC), immature neutrophil count (INC), and immature-to-total neutrophil ratio (ITR) were evaluated alone and in combination at the time of diagnosis of invasive meningococcal disease. RESULTS:: 216 patients were evaluated: meningococcemia (65), meningitis (145), and other foci (6). ANC ≤ 1000/mm or ≥ 10,000/mm was present in 137 (63%), INC ≥ 500/mm in 170 (79%), and ITR ≥0.20 in 139 (64%). One or more of these 3 criteria were met in 204/216 (94%). Results were similar for meningococcemia and meningitis subgroups. All 13 cases with mildest disease met one or more of the 3 criteria. Eight children presented with absolute neutrophil counts <1000/mm: three of them died and a fourth required partial amputation in all four limbs. CONCLUSIONS:: Invasive meningococcal disease is characterized by striking abnormalities in absolute neutrophil count, immature neutrophil count, and/or immature-to-total neutrophil ratio. Neutropenia was associated with a poor prognosis. Notably, without immature neutrophil counts, 37% of cases would have been missed. Automated methods not measuring immature WBCs should be avoided when assessing febrile children. Serious infection should be considered when counts meet any of the three criteria.
    The Pediatric Infectious Disease Journal 06/2013; · 3.57 Impact Factor
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    ABSTRACT: BACKGROUND:: The 13-valent pneumococcal conjugate vaccine (PCV13) was introduced for routine administration to infants and children in 2010 in the United States. We have monitored clinical and microbiologic features of invasive pneumococcal infections among children before and after PCV13 use. METHODS:: Infants and children cared for at 8 children hospitals in the United States with culture-proven invasive infections caused by S. pneumoniae were identified in an ongoing prospective surveillance study. Demographic and clinical data were recorded on a standard case report form. Serotype and antimicrobial susceptibilities of isolates were determined. RESULTS:: Since routine PCV13 immunization in 2010, invasive pneumococcal infections decreased 42% overall and 53% for children <24 months of age in 2011 compared with the average number of cases for 2007 to 2009. PCV13 serotype isolates decreased 57% during these same time periods; 19A, 7F and 3 decreased by 58%, 54% and 68%, respectively. The number of infections caused by serotypes 1 and 6C also decreased in 2011. The most common non-PCV13 serotypes encountered in 2010 and 2011 combined were 33F, 22F, 12, 15B, 15C, 23A and 11. Bacteremia, pneumonia and mastoiditis cases decreased more than meningitis cases. CONCLUSIONS:: After the introduction of PCV13, invasive pneumococcal infections decreased among 8 children hospitals compared with the 3 years before PCV13 use. Slight increases in some non-PCV13 serotype isolates were noted in 2011. Continued surveillance is necessary to determine the effectiveness of PCV13 including herd protection as well as any emerging invasive serotypes.
    The Pediatric Infectious Disease Journal 03/2013; 32(3):203-207. · 3.57 Impact Factor
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    ABSTRACT: Among 594 Streptococcus pneumoniae serotype 19A invasive pneumococcal disease (IPD) isolates from 1993-2011, we identified 85 sequence types (ST) by multilocus sequence typing (MLST). CC320 was associated with multidrug resistance and reduced susceptibility to penicillin and ceftriaxone and still predominated among declining serotype 19A IPD isolates following PCV13 introduction.
    Journal of clinical microbiology 02/2013; · 4.16 Impact Factor
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    ABSTRACT: BACKGROUND:: Patients with malignancies represent a population at high risk for drug resistant infections. We sought to determine the clinical spectrum and molecular epidemiology of S. aureus infections in pediatric oncology patients followed at Texas Children's Hospital (TCH). Furthermore, we determined the prevalence of the chlorhexidine resistance gene qacA/B from isolates in this unique population. METHODS:: Patients with a history of malignancy and a culture proven S. aureus infection were identified from 2001-2011. Antibiotic susceptibility, pulsed-field gel electrophoresis and detection of qacA/B by PCR were carried out on all isolates. Medical records for all patients were reviewed. RESULTS:: During the study period, 213 isolates were identified from 179 patients with malignancies. Thirty-one percent of the isolates were MRSA. The most common infectious diagnosis was bacteremia [85/213 (39.9%), with 72/85 (84.7%) being catheter-associated]. Thirteen patients with bacteremia were found to have pulmonary nodules at the time of presentation; only S. aureus was found in tissue in 5/6 patients who underwent lung biopsy. After 2007, 18.2% of isolates were qacA/B positive with a steady increase in prevalence every year (chi square for trend p value=0.04). CONCLUSIONS:: S. aureus is a significant cause of morbidity and mortality in pediatric oncology patients at TCH. In addition to the more well-known clinical manifestations, this pathogen can also be associated with pulmonary nodules. Furthermore, the prevalence of S. aureus isolates carrying antiseptic resistance genes increased in this population. Additional clinical and molecular studies and surveillance among pediatric oncology patients are warranted to further explore these findings.
    The Pediatric Infectious Disease Journal 09/2012; · 3.57 Impact Factor
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    ABSTRACT: To describe Staphylococcus aureus infections in children with diabetes mellitus (DM). Children with DM (cases) and S. aureus infections (2/02-6/10) were identified from a surveillance database. Patient charts were reviewed, and S. aureus isolates were characterized by molecular methods. Cases were compared to age-matched controls without DM but with CA-S. aureus skin and soft tissue infections (SSTI) using conditional logistic regression. Forty-seven cases were identified; 41 were matched with 123 controls. Four cases had osteomyelitis and 43 had SSTI. Mean age was 14.2 years and 63% of cases had hemoglobin (Hb) A1c levels above 10%. Cases and controls differed by gender (85% vs. 45% female, P < 0.001), BMI% (median 87% vs. 72%, P = 0.04), methicillin-resistant S. aureus (MRSA) infection (49% vs. 68%, P = 0.04), and recurrent infections (22% vs. 4%, P = 0.001). Among cases, 88% of recurrences were caused by MRSA. The majority of cases had poor glycemic control, more recurrences, fewer primary MRSA infections and were more likely to be female compared to a control group. Improved glycemic control may reduce the risk for infection, and decrease hospitalizations due to S. aureus infections.
    The Journal of infection 04/2012; 65(2):135-41. · 4.13 Impact Factor
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    ABSTRACT: A retrospective case-control study was undertaken among patients followed at the Texas Children's Hospital Retrovirology Clinic to determine the risk factors for Staphylococcus aureus infection. A total of 28 episodes of S. aureus infection were identified from 20 patients. Case patients had more advanced HIV disease as measured by CD4 T-cell counts, log10 human immunodeficiency viral load, and Centers for Disease Control and Prevention category of disease, than controls.
    The Pediatric Infectious Disease Journal 03/2012; 31(3):284-6. · 3.57 Impact Factor
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    ABSTRACT: In 2000, a 7-valent pneumococcal conjugate vaccine (PCV7) was licensed for use among US children. Many sites have since reported changes in invasive pneumococcal disease (IPD). We recognized an opportunity to describe the changes in epidemiology, clinical syndromes, and serotype distribution during a 14-year period including 4 years before vaccine introduction and spanning the entire PCV7 era. Cases were defined as children <18 years of age who were cared for at Primary Children's Medical Center for culture-confirmed IPD. We defined the prevaccine period as the time frame spanning from 1997 to 2000 and the postvaccine period from 2001 to 2010. Demographics, clinical data, and outcomes were collected through electronic query and chart review. Streptococcus pneumoniae serotyping was performed using the capsular swelling method. The median age of children with IPD increased from 19 months during the prevaccine period to 27 months during postvaccine period (P = 0.02), with a larger proportion of IPD among children older than 5 years. The proportion of IPD associated with pneumonia increased substantially from 29% to 50% (P < 0.001). This increase was primarily attributable to an increase in complicated pneumonia (17% to 33%, P < 0.001). Nonvaccine serotypes 7F, 19A, 22F, and 3 emerged as the dominant serotypes in the postvaccine period. In children with IPD who were younger than 5 years, for whom vaccine is recommended, 67% of the cases were caused by serotypes in 13-valent PCV during 2005 to 2010. After PCV7 was introduced, significant changes in IPD were noted. One-third of IPD occurred in children older than 5 years, who were outside the age-group for which PCV is recommended. Continued surveillance is warranted to identify further evolution of the epidemiology, clinical syndromes, and serotype distribution of S. pneumoniae after 13-valent PCV licensure.
    The Pediatric Infectious Disease Journal 03/2012; 31(3):228-34. · 3.57 Impact Factor
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    ABSTRACT: Streptococcus pneumoniae is a major cause of bacteremia, meningitis, pneumonia, sinusitis, and acute otitis media in children. Although optochin susceptibility, bile solubility, and Quellung testing are the standards for identifying and differentiating pneumococci, there are several reports of nontypeable pneumococci that give inconsistent results with one or more of these tests. We characterized 52 isolates previously labeled as nontypeable pneumococci. Microbiological methods included repeating the Quellung reaction using a new and expanded group of antisera, optochin susceptibility and bile solubility tests, and automated Vitek 2 identification. Molecular methods included PCR detection of ply and psaA genes, multilocus sequence typing (MLST), 16S rRNA gene sequencing, and pyrosequencing. Of the 52 isolates, 38 (73%) were optochin susceptible, were psaA and ply positive, and could be serotyped by the Quellung reaction. The remaining 14 isolates, isolated from patients with otitis media (n = 6), bacteremia (n = 6), meningitis (n = 1), and pneumonia (n = 1), underwent further analysis. Three of these 14 isolates were nontypeable due to autoagglutination but were pneumococci by all tests and represented pneumococcal sequence types previously recognized by MLST. The 11 remaining isolates were optochin resistant, and 6 of these were bile soluble. Three of 11 were both psaA and ply positive and clustered with pneumococci by MLST (2 were bile soluble); 8 lacked psaA (5 ply positive, 4 bile soluble) and likely belonged to other Streptococcus species. In conclusion, few isolates were truly nontypeable by Quellung reaction, and MLST and the presence of psaA proved useful in distinguishing between atypical pneumococci and other streptococcal species.
    Journal of clinical microbiology 01/2012; 50(4):1326-30. · 4.16 Impact Factor
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    ABSTRACT: Osteomyelitis is a common pediatric musculoskeletal infection. This infection can weaken the normal bone structure, resulting in the risk of a pathologic fracture. The purpose of this study was to evaluate the risk factors for pathologic fracture in children with Staphylococcus aureus osteomyelitis. Seventeen children who were treated for a pathologic long-bone fracture secondary to Staphylococcus aureus osteomyelitis between January 2001 and January 2009 at a tertiary-care pediatric hospital were identified. These patients were compared with a control group consisting of forty-nine children with Staphylococcus aureus osteomyelitis without a fracture who were matched for age, sex, and methicillin susceptibility. A retrospective review of the clinical records, magnetic resonance imaging (MRI) studies, and microbiologic findings was performed. Patients who developed a fracture presented with osteomyelitis at a mean age of 8.8 years (range, two to seventeen years). Fifteen of the seventeen patients had methicillin-resistant Staphylococcus aureus (MRSA) isolates, and two had methicillin-susceptible Staphylococcus aureus (MSSA). The mean time from disease onset to fracture was 72.1 days (range, twenty to 150 days). The duration of hospitalization, number of surgical procedures, duration of antibiotic treatment, and total number of complications differed significantly between the two groups. MRI studies at the time of admission demonstrated a significantly greater prevalence of subperiosteal abscess and greater circumferential size of such an abscess in the patients with a fracture. A sharp zone of abnormally diminished enhancement of the marrow was also more common in these patients. The USA300-0114 pulsotype was more commonly associated with an elevated likelihood of fracture. Staphylococcus aureus osteomyelitis is a serious infection that may predispose children to pathologic fractures. Protected weight-bearing and activity restriction are recommended in children with Staphylococcus aureus osteomyelitis who have the risk factors demonstrated in this study.
    The Journal of Bone and Joint Surgery 01/2012; 94(1):34-42. · 3.23 Impact Factor
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    ABSTRACT: Previous studies have reported that contrast-enhanced sequences do not increase the sensitivity of MRI for the diagnosis of pediatric osteomyelitis and are not needed in the absence of edema on unenhanced MRI sequences. Invasive skeletal infections due to community-acquired Staphylococcus aureus are increasingly encountered in infants and young children and have a proclivity for involvement of both the unossified growth cartilage and the metadiaphyseal bone marrow of the extremities. The study objective is to assess the diagnostic efficacy of contrast-enhanced and unenhanced MRI sequences for the diagnosis of community-acquired S. aureus extremity skeletal infection in infants and young children. A retrospective review was conducted of the clinical charts and imaging studies of patients younger than 18 months diagnosed with invasive community-acquired S. aureus skeletal infections from 2001 to 2009 at a large children's hospital. Sensitivity was calculated for the detection of skeletal infection on contrast-enhanced and unenhanced MRI sequences. The p values were calculated using the Fisher exact score method. The kappa value for interobserver reliability was determined. Community-acquired S. aureus skeletal infections were noted in 34 extremity sites in 25 patients, five of whom had more than one site of disease. The affected skeletal sites were metaphyseal or metadiaphyseal bone marrow only in 16 cases (47%), unossified growth cartilage only in nine cases (26%), and both the unossified growth cartilage and metaphyseal or metadiaphyseal bone marrow in nine cases (26%). In seven of the nine cases of isolated involvement of the unossified growth cartilage, the cartilage appeared normal on unenhanced sequences and the diagnosis was made only by the demonstration of hypoenhancing or nonenhancing foci in the cartilage after gadolinium-based contrast agent administration. In five of the nine cases of infection of both the unossified growth cartilage and metaphyseal or metadiaphyseal bone marrow, neither the cartilage nor bone marrow appeared abnormal on unenhanced sequences. Therefore, 12 cases of skeletal infection would have been missed without the inclusion of contrast-enhanced sequences. Follow-up extremity radiographs were available for 10 patients, eight (80%) of whom exhibited growth disturbances. Skeletal infection caused by community-acquired S. aureus in infants and young children manifests differently than in older children, including a propensity for involvement of the unossified growth cartilage and potentially occult nature of both cartilage and bone marrow involvement on unenhanced MRI sequences.
    American Journal of Roentgenology 01/2012; 198(1):194-9. · 2.90 Impact Factor
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    ABSTRACT: While heptavalent pneumococcal conjugate vaccine (PCV) has decreased vaccine type invasive pneumococcal disease (IPD) nationwide, rapid serotype replacement and increasing parapneumonic empyema, has been reported in Utah children. The effect of pediatric vaccination on adults in this population is unknown. We identified 117 adults with IPD from the Intermountain Healthcare Central Laboratory between November 2009 and October 2010. We serotyped 61 (52%) stored isolates. We compared the serotype distribution of adult IPD isolates with that of pediatric isolates collected in 2009-2010. PCV7 serotypes were rare in adults (3%) and children (3%). Emerging 13-valent PCV serotypes 3, 7F, and 19A caused the majority of IPD in adults (63%) and children (56%). Fifty-one (84%) adult isolates were serotypes included in 23-valent polysaccharide vaccine and 66% in PCV13. Adult and pediatric IPD serotypes are closely associated in Utah. PCV13 vaccination in Utah children is likely to significantly impact IPD in Utah adults.
    Vaccine 11/2011; 29(49):9123-6. · 3.77 Impact Factor
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    ABSTRACT: Streptococcus pneumoniae serotype 6C, which was described in 2007, causes invasive disease in adults and children. We investigated the prevalence of 6C among pediatric isolates obtained from eight children's hospitals in the United States. S. pneumoniae isolates were identified from a prospective multicenter study (1993 to 2009). Fifty-seven serotype 6C isolates were identified by multiplex PCR and/or Quellung reaction. Five were isolated before 2000, and the prevalence increased over time (P < 0.000001). The median patient age was 2.1 years (range, 0.2 to 22.5 years). Clinical presentations included bacteremia (n = 24), meningitis (n = 7), pneumonia (n = 4), abscess/wound (n = 3), mastoiditis (n = 2), cellulitis (n = 2), peritonitis (n = 1), septic arthritis (n = 1), otitis media (n = 10), and sinusitis (n = 3). By broth microdilution, 43/44 invasive serotype 6C isolates were susceptible to penicillin (median MIC, 0.015 μg/ml; range, 0.008 to 2 μg/ml); all were susceptible to ceftriaxone (median MIC, 0.015 μg/ml; range, 0.008 to 1 μg/ml). By disk diffusion, 16/44 invasive isolates (36%) were nonsusceptible to erythromycin, 19 isolates (43%) were nonsusceptible to trimethoprim-sulfamethoxazole (TMP-SMX), and all isolates were clindamycin susceptible. Multilocus sequence typing (MLST) revealed 24 sequence types (STs); 9 were new to the MLST database. The two main clonal clusters (CCs) were ST473 and single-locus variants (SLVs) (n = 13) and ST1292 and SLVs (n = 23). ST1292 and SLVs had decreased antibiotic susceptibility. Serotype 6C causes disease in children in the United States. Emerging CC1292 expressed TMP-SMX resistance and decreased susceptibility to penicillin and ceftriaxone. Continued surveillance is needed to monitor changes in serotype prevalence and possible emergence of antibiotic resistance in pediatric pneumococcal disease.
    Journal of clinical microbiology 03/2011; 49(6):2097-101. · 4.16 Impact Factor

Publication Stats

6k Citations
839.66 Total Impact Points


  • 1988–2013
    • Texas Children's Hospital
      Houston, Texas, United States
  • 2005–2012
    • University of Utah
      • • Department of Pediatrics
      • • School of Medicine
      Salt Lake City, UT, United States
    • University of Arkansas for Medical Sciences
      Little Rock, Arkansas, United States
  • 1981–2012
    • Baylor College of Medicine
      • • Department of Pediatrics
      • • Section of Infectious Diseases
      • • Department of Surgery
      Houston, TX, United States
  • 1996–2005
    • University of Texas Health Science Center at Houston
      • Department of Pathology and Laboratory Medicine
      Houston, Texas, United States
  • 2000–2004
    • Wake Forest School of Medicine
      • Department of Pediatrics
      Winston-Salem, NC, United States
  • 2003
    • Childrens Hospital of Pittsburgh
      • Division of Pediatric Infectious Diseases
      Pittsburgh, Pennsylvania, United States
    • University of Southern California
      • Department of Pediatrics
      Los Angeles, CA, United States
  • 2002
    • Children's Memorial Hospital
      Chicago, Illinois, United States
  • 1997–2002
    • University of Arkansas at Little Rock
      Little Rock, Arkansas, United States
  • 1999
    • University of Illinois at Chicago
      • Pediatric Division of Infectious Diseases (Chicago)
      Chicago, IL, United States
    • Arkansas Children's Hospital
      Little Rock, Arkansas, United States
    • University of California, San Diego
      San Diego, California, United States
  • 1998
    • University of California, Los Angeles
      • Division of Infectious Diseases
      Los Angeles, CA, United States
  • 1991
    • The Ohio State University
      Columbus, Ohio, United States
  • 1988–1989
    • Washington University in St. Louis
      • Department of Pediatrics
      Saint Louis, MO, United States