Biomedical subjects
Publications and source records attributed to Lisa Saiman.
Infections caused by extended-spectrum beta-lactamase (ESBL)-producing pathogens, particularly Klebsiella pneumoniae, are increasing. The epidemiology of ESBL-producing K. pneumoniae, the mechanisms of resistance, and treatment strategies for infections caused by these organisms are reviewed.
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OBJECTIVE: To describe the epidemiologic and molecular investigations that successfully contained an outbreak of methicillin-resistant Staphylococcus aureus (MRSA) in a neonatal intensive care unit (NICU). DESIGN: Isolates of MRSA were typed by pulsed-field gel electrophoresis (PFGE) and S. aureus protein A (spa). SETTING: A level III-IV, 45-bed NICU located in a children's hospital within a medical center. PATIENTS: Incident cases had MRSA isolated from clinical cultures (eg, blood) or surveillance cultures (ie, anterior nares). INTERVENTIONS: Infected and colonized infants were placed on contact precautions, cohorted, and treated with mupirocin. Surveillance cultures were performed for healthcare workers (HCWs). Colonized HCWs were treated with topical mupirocin and hexachlorophene showers. RESULTS: From January to March 2001, the outbreak strain of MRSA, PFGE clone B, was harbored by 13 infants. Three (1.3%) of 235 HCWs were colonized with MRSA. Two HCWs, who rotated between the adult and the pediatric facility, harbored clone C. One HCW, who exclusively worked in the children's hospital, was colonized with clone B. From January 1999 to November 2000, 22 patients hospitalized in the adult facility were infected or colonized with clone B. Spa typing and PFGE yielded concordant results. PFGE clone B was identified as spa type 16, associated with outbreaks in Brazil and Hungary. CONCLUSIONS: A possible route of MRSA transmission was elucidated by molecular typing. MRSA appears to have been transferred from our adult facility to our pediatric facility by a rotating HCW. Spa typing allowed comparison of our institution's MRSA strains with previously characterized outbreak clones.
OBJECTIVES: To determine the costs of the interventions aimed at controlling the 4-month outbreak and to determine the attributable length of stay (LOS) associated with infection and colonization with extended-spectrum beta-lactamase-producing Klebsiella pneumoniae. DESIGN: A retrospective cost analysis was conducted from the hospital perspective. A micro-costing approach was employed. The LOS of four groups of hospitalized patients were compared with each other. National Perinatal Information Center criteria were used to stratify infants for severity of risk. The LOS of each group was compared with that of a national sample of similarly stratified infants. SETTING: A level III-IV, 45-bed neonatal intensive care unit. PATIENTS: Infant groups were infected (n = 8), colonized (n = 14), concurrent cohort (n = 54), and prior cohort (n = 486). RESULTS: The cost of the outbreak totaled 341,751 dollars. The largest proportion of costs was related to healthcare worker time providing direct patient care (2,489 hours at a cost of 146,331 dollars). Infected and colonized neonates had longer LOS than either the concurrent cohort or the prior cohort (P < .001). Compared with the national sample, infected infants had a 48.5-day longer mean LOS (95% confidence interval [CI95], 1.7 to 95.2), whereas the prior cohort's mean LOS was 6 days shorter (CI95, -9.4 to -2.9). CONCLUSIONS: This study increases the understanding of the burden of these multidrug-resistant organisms. Further research is needed to estimate the societal costs of these infections and the cost-effectiveness of preventive interventions.
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OBJECTIVE: To determine whether hand hygiene practices differ between levels of contact with neonates; to characterize the hand hygiene practices of different types of personnel; and to compare hand hygiene practices in neonatal intensive care units (NICUs) using different products. METHODS: Research assistants observed staff hand hygiene practices during 38 sessions in two NICUs. Patient touches were categorized as touching within the neonates' environment but only outside the Isolette (Level 1), touching within the Isolette but not the neonate directly (Level 2) or directly touching the neonate (Level 3). Hand hygiene practices for each touch were categorized into five groups: cleaned hands and new gloves; uncleaned hands and new gloves; used gloves; clean hands and no gloves; uncleaned hands and no gloves. RESULTS: Research assistants observed 1472 touches. On average each neonate or his or her immediate environment was touched 78 times per shift. Nurses (P = 0.001), attending physicians (P = 0.02) and physicians-in-training (P = 0.03) were more likely to use appropriate practices during Level 3 touches, but only 22.8% of all touches were with cleaned and/or newly gloved hands. The mean number of direct touches by staff members with cleaned hands was greater in the NICU using an alcohol-based hand rub than in the NICU using antimicrobial soap (P < 0.01). CONCLUSIONS: Hand hygiene was suboptimal in this high risk setting; administrative action and improved products may be needed to assure acceptable practice. In this study use of an alcohol-based product was associated with significantly improved hand hygiene and should be encouraged, as recommended in the new CDC hand hygiene guideline.
Accurate identification of gram-negative bacilli from cystic fibrosis (CF) patients is essential. Only 57% (108 of 189) of nonmucoid strains and 40% (24 of 60) of mucoid strains were definitively identified as Pseudomonas aeruginosa with MicroScan Autoscan. Most common misidentifications were Pseudomonas fluorescens-Pseudomonas putida (i.e., the strain was either P. fluorescens or P. putida, but the system did not make the distinction and yielded the result P. fluorescens/putida) and Alcaligenes spp. Extending the incubation to 48 h improved identification, but 15% of isolates remained misidentified. The MicroScan Autoscan system cannot be recommended for the identification of P. aeruginosa isolates from CF patients.
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The varicella vaccine was approved in 1995 for use in healthy varicella-susceptible children and adults. Long-term immunity in 461 healthy adults who were enrolled in varicella vaccine trials in 1979-1999 were studied. Forty vaccinees (9%), including 19 (21%) of 89 vaccinees with household exposure (HHE) to chickenpox, developed breakthrough chickenpox 8 weeks to 11.8 years (mean, 3.3 years) after vaccination. The median number of skin lesions among the 36 untreated vaccinees was 20 (range, 1-240 lesions), and the number of lesions was essentially the same with time since vaccination. Breakthrough chickenpox was mild, even among vaccinees who did not have seroconversion or those recipients who lost detectable antibody. Lower varicella-zoster virus (VZV) antibody titers measured within 3 months of vaccination as well as at the time of HHE were associated with an increased risk of breakthrough disease. This study demonstrated that the varicella vaccine was effective in providing adults with long-term protection from serious VZV disease.
Infants in the neonatal intensive care unit (NICU) have many risk factors for infection. Compared with older children and adults, infants, particularly premature infants, are relatively immunocompromised. Patients in the NICU have intrinsic risk factors for infections due to immunological "deficiencies" or inadequate development of mechanical barriers such as skin and gastrointestinal tract mucosa. Like other ICU populations, NICU patients have extrinsic risk factors for infection such as prolonged hospitalization, invasive procedures, instrumentation, medical treatments and concomitant medical conditions. Compared with healthy full-term infants, patients in the NICU develop abnormal flora, which is generally acquired in the NICU from patient-to-patient transmission via hand carriage of healthcare workers. This flora is frequently multidrug-resistant as it has developed under the selective pressure of antibiotics and can cause invasive disease. An understanding of the risk factors that are associated with hospital-acquired infections is essential to design preventive strategies.
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Cystic fibrosis (CF) is an autosomal-recessive disorder and affects about 60,000 people worldwide. The CF gene, the cystic fibrosis transmembrane conductance regulator (CFTR), was found in 1989 and over 800 mutations have been sequenced. Although our understanding of the pathophysiology of CF has increased, pulmonary infections remain the major cause of morbidity and mortality. During the first decade of life, Staphylococcus aureus and nontypable Haemophilus influenza are most common, but Pseudomonas aeruginosa may be the first pathogen isolated in infants. By 18 years of age, 80% of patients harbor P. aeruginosa and 3.5% harbor Burkholderia cepacia. Stenotrophomonas maltophilia, Achromobacter xylosoxidans, and nontuberculous mycobacteria may be newly emerging CF pathogens. The traditional approach to managing patients with CF is to treat acute pulmonary exacerbations with intravenous antimicrobial agents. However, prophylactic strategies to prevent initial infection or to delay chronic infection with P. aeruginosa or chronic maintenance therapy to slow deterioration of lung function may also improve clinical status. Recognition of the role of inflammation, even early in life, in the absence of clinical symptoms, has led to treatment with anti-inflammatory agents. Novel strategies to disrupt biofilm formation, stimulate chloride conductance, and replace abnormal CFTR are currently being studied.
BACKGROUND: Patient-to-patient transmission of methicillin-resistant Staphylococcus aureus (MRSA) in neonatal intensive care units (NICUs) has been well described. We report the first documented outbreak of probable transmission of MRSA from a mother to 3 of her preterm quadruplet infants postnatally. METHODS: Routine surveillance of clinical microbiologic laboratory reports revealed an increased incidence of MRSA infections in our NICU, including 3 of 4 preterm quadruplets. Surveillance cultures of the anterior nares of all patients and the quadruplets' parents were performed to detect MRSA carriage. The isolates were typed by pulsed-field gel electrophoresis with the restriction endonuclease SmaI. Infection control strategies included mupirocin treatment and contact isolation precautions for infected/colonized infants. RESULTS: Clinical cultures from infants A, C, and D and surveillance cultures of the quadruplets' mother and 2 additional unrelated infants grew the same clone of MRSA. The mother's only identified risk factors for MRSA acquisition were 2 prepartum hospitalizations related to the multiple gestation and previous treatment with antibiotics. All anterior nares cultures were negative for MRSA after mupirocin treatment. CONCLUSIONS: Use of gowns and gloves by the family members of women with multiple gestations should be recommended to prevent transmission of potential pathogens in the NICU.
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OBJECTIVE: When the incidence of methicillin-susceptible Staphylococcus aureus (MSSA) infection or colonization increased in our neonatal intensive care unit (NICU), we sought to further our understanding of the relationship among colonization with MSSA, endemic infection, and clonal spread. DESIGN: A retrospective cohort study was used to determine risk factors for acquisition of a predominant clone of MSSA (clone "B"). SETTING: A 45-bed, university-affiliated, level III-IV NICU. PATIENTS: Infants hospitalized in the NICU from October 1999 to September 2000. INTERVENTIONS: Infection control strategies included surveillance cultures of infants, cohorting infected or colonized infants, contact precautions, universal glove use, mupirocin treatment of the anterior nares of all infants in the NICU, and a hexachlorophene bath for infants weighing 1,500 g or more. RESULTS: During the 1-year study period, three periods of increased incidence of MSSA colonization or infection, ranging from 6.4 to 13.5 cases per 1,000 patient-days per month, were observed. Molecular typing using pulsed-field gel electrophoresis demonstrated two predominant clones, clone "B" and clone "G," corresponding to two periods of increased incidence. Multivariate analysis demonstrated that length of stay (OR, 1.035; 95% confidence interval [CI95], 1.008 to 1.062; P = .010) increased risk per day) and the use of H2-blockers (OR, 20.44; CI95, 2.48 to 168.26; P = .005) were risk factors for either colonization or infection with clone "B," and that the use of peripheral catheters was protective (OR, 0.06; CI95, 0.01 to 0.43; P= .005). CONCLUSIONS: Control of MSSA represents unique challenges as colonization is expected, endemic infections are tolerated, and surveillance efforts generally focus on multidrug-resistant pathogens. Future studies should address cost-effective surveillance strategies for endemic infections.
The successful treatment of a 7-month-old infant with shunt-associated ventriculitis caused by vancomycin-resistant Enterococcus faecium is presented. Linezolid was administered intravenously every 8 h; children have a greater volume of distribution and total body clearance than adults and therefore require more frequent dosing. The patient tolerated the therapy without adverse effects.
Azithromycin and clarithromycin were paired with other antibiotics to test synergistic activity against 300 multidrug-resistant pathogens isolated from cystic fibrosis (CF) patients. Clarithromycin-tobramycin was most active against Pseudomonas aeruginosa and inhibited 58% of strains. Azithromycin-trimethoprim-sulfamethoxazole, azithromycin-ceftazidime, and azithromycin-doxycycline or azithromycin-trimethoprim-sulfamethoxazole inhibited 40, 20, and 22% of Stenotrophomonas maltophilia, Burkholderia cepacia complex, and Achromobacter (Alcaligenes) xylosoxidans strains, respectively.
BACKGROUND: Increasing numbers of families in the United States are adopting children who were born in other countries. Appropriate immunization of internationally adopted children provides a challenge to pediatricians who must evaluate documentation of vaccines administered overseas and fulfill the recommended US childhood immunization schedule. The acceptability of vaccinations received outside the United States was addressed by the Advisory Committee on Immunization Practices in 1994, but few population-based studies assessing these vaccinations have been reported. METHODS: We performed a retrospective cohort study of 504 children who were adopted from other countries and evaluated in 1997 and 1998. Our goal was to determine the acceptability of overseas vaccinations for meeting US immunization requirements. We assessed immunization records for both valid documentation of receipt of vaccine and comparability with the recommended US schedule. We also determined the number of children who were up to date (UTD) for diphtheria-tetanus-pertussis, polio, hepatitis B, and measles-mumps-rubella vaccines under the US schedule. RESULTS: The children's mean age at initial US evaluation was 19 months; 71% were girls, and most (88%) had resided in orphanages. They were adopted from 16 countries, most frequently from China (48%) and Russia (31%). Thirty-five percent (178) of children had overseas immunization records, 167 (94%) of which were considered valid. Most children with valid records (112 [67%] of 167) were UTD for 1 or more vaccine series under the US schedule. CONCLUSION: The majority (65%) of internationally adopted children had no written records of overseas immunizations. Among the 178 children with documented overseas immunizations, 167 (94%) had valid records and some vaccine doses that were acceptable and UTD under the US schedule. Additional research and more specific guidance in the most cost-effective approaches to evaluation of overseas vaccinations are needed to ensure appropriate state-side vaccination and to improve the health of these children and their communities.