Steven C. Buckingham

Emergence of community-associated methicillin-resistant Staphylococcus aureus at a Memphis, Tennessee Children's Hospital.

Background: An epidemiologic investigation was performed because of a perceived increase in infections caused by community-associated methicillin-resistant Staphylococcus aureus (MRSA) among children in the greater Memphis area. Methods: We reviewed medical records of 289 children evaluated from January 2000 to June 2002 at a childrens hospital. Clinical criteria were applied to classify MRSA isolates as community-associated (n=51) or health care-associated (n=138). The relatedness of 33 archived S. aureus isolates was evaluated using pulsed field gel electrophoresis (PFGE) of Sma I-digested genomic DNA; a common pulsed field type was defined as ≥80% similarity based on Dice coefficients. PFGE profiles were compared with those in a national database of MRSA isolates. Results: During the first 18 study months, 46 of 122 MRSA isolates (38%) were community-associated; this proportion increased to 106 of 167 isolates (63%) during the last 12 study months (P < .0001). Community-associated isolates were recovered from normally sterile sites as frequently as were health care-associated isolates (16% versus 13%). PFGE revealed that 15 of 16 community-associated isolates shared a common pulsed field type (USA300) observed in community-associated MRSA infections elsewhere in the United States and characterized by staphylococcal cassette chromosome mec type IV, clindamycin susceptibility and erythromycin resistance mediated by an msr A-encoded macrolide efflux pump. Conclusions: Community-associated MRSA has emerged as a potentially invasive pathogen among children in the greater Memphis area, and this phenomenon is not explained by spread of nosocomial strains into the community.

Incidence and etiologies of complicated parapneumonic effusions in children, 1996 to 2001.

Background. The incidence and causative organisms associated with complicated parapneumonic effusions in children with community-acquired pneumonia are likely to have changed during the past several years. Methods. Data regarding clinical and laboratory features were abstracted retrospectively from medical records of 76 subjects with complicated parapneumonic effusions at a tertiary children’s hospital from 1996 through 2001. Incidence rates per 10 000 hospital discharges and per 1000 patients with nonviral pneumonia were calculated. Results. Etiologic organisms were Streptococcus pneumoniae (31 subjects), Staphylococcus aureus (7), Streptococcus pyogenes (5), Abiotrophia sp. (1) and no culture-confirmed agent (32). The annual incidence of complicated parapneumonic effusions per 10 000 discharges progressively increased from 4.5 in 1996 to 25.0 in 1999 (P = 0.0001), then declined to 10.1 in 2001 (P = 0.03). Similarly the incidence per 1000 cases of nonviral pneumonia increased from 2.9 in 1996 to 11.0 in 1999 (P = 0.003) and then declined to 4.8 in 2001 (P = 0.053). Whereas S. pneumoniae was the leading confirmed etiology in each year, the proportion of cases caused by Staphylococcus aureus increased from 6% in 1996 to 2000 (all of which were methicillin-susceptible) to 30% in 2001 (all methicillin-resistant;P = 0.04). Conclusions. The incidence of complicated parapneumonic effusions in children with community-acquired pneumonia increased from 1996 to 1999 and then declined concomitant with the introduction of the pneumococcal conjugate vaccine. Although cases caused by S. pneumoniae have decreased, community onset methicillin-resistant Staphylococcus aureus has emerged as a cause of pneumonia with complicated effusions in children.

Nasal quantity of respiratory syncytial virus correlates with disease severity in hospitalized infants.

Objective. To evaluate the relationship between nasal quantity of respiratory syncytial virus (RSV) and disease severity in hospitalized infants without underlying cardiopulmonary disease or immunodeficiency. Methods. Nasal aspirates were obtained from hospitalized infants <24 months of age with recently identified RSV infection and evaluated for RSV quantity by a standard plaque assay on HEp‐2 cell monolayers. Subjects were classified as having “severe” disease if they required mechanical ventilation at the time of sample collection and as having “nonsevere” disease if they did not. Linear modeling was used to determine the relationship between nasal RSV quantity and various independent variables, including disease severity. Results. Nasal aspirates from 39 patients were evaluated. Age, gender and mean duration of time from symptom onset to sample acquisition (5 days) were similar between the severe (n = 15) and nonsevere (n = 24) groups. Significantly more infants were born at <35 weeks gestation in the severe disease group (7 of 15 vs. 3 of 24, P = 0.017), and infants born at <35 weeks gestation were significantly more likely to be of non‐Caucasian ethnicity than were infants born at ≥35 weeks gestation (8 of 10 vs. 12 of 29, P = 0.035). The linear model found that higher nasal RSV quantities were associated with severe disease [mean ± SEM, 5.06 ± 0.34 log plaque‐forming units (pfu)/ml vs. 3.91 ± 0.35 log pfu/ml, P = 0.022], gestational age ≥35 weeks (5.44 ± 0.27 log pfu/ml vs. 3.52 ± 0.45 log pfu/ml, P = 0.002) and non‐Caucasian ethnicity (5.16 ± 0.30 log pfu/ml vs. 3.80 ± 0.37 log pfu/ml, P = 0.006). Conclusions. Nasal RSV quantity correlates with disease severity in hospitalized infants with recently identified RSV infection.

From Pig to Pacifier: Chitterling-Associated Yersiniosis Outbreak among Black Infants

In this case-control study of Yersinia enterocolitica infections among black infants, chitterling preparation was significantly associated with illness (p<0.001). Of 13 samples of chitterlings tested, 2 were positive for Yersinia intermedia and 5 for Salmonella. Decontamination of chitterlings before sale with methods such as irradiation should be strongly considered.

Respiratory syncytial virus infections in the pediatric intensive care unit: clinical characteristics and risk factors for adverse outcomes.

Objectives To describe the clinical characteristics of infants admitted to a pediatric intensive care unit (PICU) with respiratory syncytial virus (RSV) infection, including the prevalence of indications for RSV passive antibody prophylaxis (as currently recommended by the American Academy of Pediatrics), and to identify risk factors that predict adverse outcomes among this population. Design Retrospective medical record review. Setting Tertiary care PICU. Patients Children <2 yrs of age admitted to PICU for the management of RSV disease during the 1994–95, 1995–96, and 1996–97 RSV seasons. Measurements and Main Results The medical records of 89 infants were reviewed. Of these, 55% were born before 36-wks gestation, 14% had chronic lung disease that required medical therapy within the previous 6 months, and 30% met at least one indication for RSV passive antibody prophylaxis. Seven infants had congenital heart disease, five had upper airway abnormalities, and six had various noncardiac congenital malformations. Logistic regression was used to determine which characteristics were associated with prolonged durations (>75th percentile) of mechanical ventilation, PICU stay, and hospital stay. Prolonged mechanical ventilation was associated with congenital heart disease (p = 0.014), chronic lung disease (p = 0.007), and noncardiac congenital malformations (p = 0.022). Only congenital heart disease was associated with prolonged PICU stay (p = 0.004) or prolonged hospital stay (p = 0.006). All of the infants with airway abnormalities had prolonged ventilator days, PICU days, and hospital days. Currently recommended indications for RSV passive antibody prophylaxis were not predictive of prolonged ventilation, PICU stay, or hospital stay. Conclusions A minority of infants admitted to our PICU for severe RSV disease meet currently recommended indications for RSV passive antibody prophylaxis. Risk factors that predict prolonged durations of ventilation, PICU stay, or hospital stay among this population include congenital heart disease, chronic lung disease, upper airway abnormalities, and noncardiac congenital malformations.

Human monocytic ehrlichiosis in children.

Background: Human monocytic ehrlichiosis (HME) is a tick-borne illness caused by Ehrlichia chaffeensis. Data about disease in children have been largely derived from case reports or small case series. Methods: A retrospective review of all medical and laboratory records from 6 sites located in the “tick belt” of the Southeastern United States was carried out. Demographic, history and laboratory data were abstracted from the identified medical records of patients. Bivariate statistical comparisons were performed using Fisher exact test or Wilcoxon rank sum tests. Results: Common clinical signs and symptoms of patients with HME (n = 32) included fever (100%), headache (69%), myalgia (69%), rash (66%), nausea/vomiting (56%), altered mental status (50%) and lymphadenopathy (47%). Only 48% had a complaint of fever, headache and rash. Common laboratory abnormalities included thrombocytopenia (94%), elevated aspartate aminotransferase (90%), elevated alanine aminotransferase (74%), hypoalbuminemia (65%), lymphopenia (57%), leukopenia (56%) and hyponatremia (55%). The median number of days of illness before the initiation of antirickettsial therapy was 6. Patients who received sulfonamides before starting doxycycline therapy developed a rash, were admitted to the hospital, and started doxycycline at a later date. Twenty-two percent of patients were admitted to the intensive care unit with 12.5% of patients requiring ventilatory and blood pressure support. Conclusions: Although HME has been recognized among children for almost 20 years, there is only a limited knowledge about its clinical course. Even among physicians practicing in endemic regions, few cases are diagnosed each year. More work is needed to understand the true burden of disease and the natural history among asymptomatically and symptomatically infected children.

Pneumococcal meningitis in children: relationship of antibiotic resistance to clinical characteristics and outcomes.

Background. The relationship of antibiotic susceptibility to clinical outcome in children with pneumococcal meningitis is uncertain. Previous studies have been limited by inclusion of relatively few patients infected with nonsusceptible pneumococci and inconsistent use of empiric vancomycin. Methods. Medical records of 86 children with culture-confirmed pneumococcal meningitis at a single institution from October, 1991, to October, 1999, were retrospectively reviewed, and differences in presentation and outcome based on antibiotic susceptibility of pneumococcal isolates were assessed. Results. Of 86 isolates 34 were nonsusceptible to penicillin (12 resistant). Of 60 isolates for which cefotaxime susceptibility data were available, 17 were nonsusceptible (12 resistant). Antibiotic susceptibility was not significantly associated with death, intensive care unit admission, mechanical ventilation, focal neurologic deficits, seizures, secondary fever, abnormal neuroimaging studies or hospital days. Children with penicillin-resistant isolates had significantly higher median blood leukocyte counts (24 100/&mgr;l vs. 15 700/&mgr;l, P = 0.03) and lower median CSF protein concentrations (85 mg/dl vs. 219 mg/dl, P = 0.04), were more likely to have a CSF glucose concentration of ≥50 mg/dl (7 of 11 vs. 15 of 68, P = 0.009) and had lower rates of sensorineural hearing loss (1 of 8 vs. 25 of 40, P = 0.02) than children with isolates that were not resistant to penicillin. Children with cefotaxime-nonsusceptible isolates had an increased median duration of primary fever compared with those with nonsusceptible strains (6 days vs. 3.5 days, P = 0.02). Conclusions. In children with pneumococcal meningitis, penicillin resistance was associated with a reduced risk of hearing loss, while cefotaxime resistance was associated with a longer duration of fever. Other outcome measures were not significantly influenced by the antibiotic susceptibility of pneumococcal isolates.

Early Vancomycin Therapy and Adverse Outcomes in Children With Pneumococcal Meningitis

BACKGROUND. Experts recommend that children with suspected pneumococcal meningitis should empirically receive combination therapy with vancomycin plus either ceftriaxone or cefotaxime. The relationship between timing of the first dose of vancomycin relative to other antibiotics and outcome in these children, however, has not been addressed. METHODS. Medical records of children with pneumococcal meningitis at a single institution from 1991–2001 were retrospectively reviewed. Vancomycin start time was defined as the number of hours from initiation of cefotaxime or ceftriaxone therapy until the administration of vancomycin therapy. Outcome variables were death, sensorineural hearing loss, and other neurologic deficits at discharge. Associations between independent variables and outcome variables were assessed in univariate and multiple logistic regression analyses. RESULTS. Of 114 subjects, 109 received empiric vancomycin therapy in combination with cefotaxime or ceftriaxone. Ten subjects (9%) died, whereas 37 (55%) of 67 survivors who underwent audiometry had documented hearing loss, and 14 (13%) of 104 survivors were discharged with other neurologic deficits. Subjects with hearing loss had a significantly shorter median vancomycin start time than did those with normal hearing (<1 vs 4 hours). Vancomycin start time was not significantly associated with death or other neurologic deficits in univariate or multivariate analyses. Multiple logistic regression revealed that hearing loss was independently associated with vancomycin start time <2 hours, blood leukocyte count <15000/μL, and cerebrospinal fluid glucose concentration <30 mg/dL. CONCLUSIONS. Early empiric vancomycin therapy was not clinically beneficial in children with pneumococcal meningitis but was associated with a substantially increased risk of hearing loss. It may be prudent to consider delaying the first dose of vancomycin therapy until ≥2 hours after the first dose of parenteral cephalosporin in children beginning therapy for suspected or confirmed pneumococcal meningitis.

Managing Rocky Mountain spotted fever.

Rocky Mountain spotted fever is caused by the tick-borne bacterium Rickettsia rickettsii. Symptoms range from moderate illness to severe illness, including cardiovascular compromise, coma and death. The disease is prevalent in most of the USA, especially during warmer months. The trademark presentation is fever and rash with a history of tick bite, although tick exposure is unappreciated in over a third of cases. Other signature symptoms include headache and abdominal pain. The antibiotic therapy of choice for R. rickettsii infection is doxycycline. Preventive measures for Rocky Mountain spotted fever and other tick-borne diseases include: wearing long-sleeved, light colored clothing; checking for tick attachment and removing attached ticks promptly; applying topical insect repellent; and treating clothing with permethrin.

Fungal peritonitis caused by Curvularia species in a child undergoing peritoneal dialysis

Abstract We report the first case of peritonitis caused by Curvularia species in a child undergoing peritoneal dialysis. He presented with gray-black proteinaceous material obstructing the lumen of his Tenckhoff catheter. Although the peritoneal fluid was cloudy, the patient suffered neither significant abdominal tenderness nor systemic symptoms. Catheter removal and treatment with amphotericin B allowed complete recovery and return to peritoneal dialysis within 7 days. Outdoor play in a wooded environment may have allowed contact of this saprophytic fungus with the child’s indwelling catheter transfer set.