Human Parechovirus and Other Enteric Viruses in Childcare Attendees in the Era of Rotavirus Vaccines.

OBJECTIVE: We studied the prevalence of enteric viruses, including rotavirus, enterovirus, norovirus, adenovirus, and human parechovirus (HPeV), in stool samples of childcare attendees. The prevalence of enteric viruses was described in children with and those without gastroenteritis. METHODS: Children aged 1-19 months were recruited from 2 childcare centers in Tacoma, Washington, from October 2008 through June 2009. Stool samples were obtained at enrollment and during diarrheal illnesses for enteric virus testing. A symptom diary was completed by parents. RESULTS: One hundred six children (mean age, 10 months) were followed for an average of 170 days. At enrollment, 78 asymptomatic children had stool samples available. Forty-eight illnesses with acute diarrhea (stool samples were available for 24 illnesses) occurred in 37 children. Rotavirus was not detected in samples from symptomatic or asymptomatic children. HPeV was present in 21% and adenovirus in 46% of symptomatic children. At least 1 virus was detected in 78% of samples from asymptomatic children, including HPeV in 27% and adenovirus in 55%. No differences were found in symptom prevalence between HPeV-positive and HPeV-negative diarrheal illnesses. Molecular analysis revealed a diversity of HPeV types. CONCLUSIONS: Our study highlights the high level of HPeV circulation in childcare. The lack of rotavirus detected in this study supports the impact of rotavirus vaccine and emphasizes the need for a greater focus on the epidemiology of non-rotavirus etiologies of gastroenteritis.

Capsular serotype of Staphylococcus aureus in the era of community-acquired MRSA.

Capsular polysaccharide (CP) plays an important role in the pathogenicity and immunogenicity of Staphylococcus aureus, yet the common serotypes of S. aureus isolated from US pediatric patients have not been reported. We investigated capsular serotype as well as methicillin susceptibility, presence of Panton-Valentine leukocidin (PVL), and clonal relatedness of pediatric S. aureus isolates. Clinical isolates were tested for methicillin susceptibility, presence of mecA, lukS-PV and lukF-PV, cap5 and cap8 genes by PCR, and for capsular or surface polysaccharide expression (CP5, CP8, or 336 polysaccharide) by agglutination. Genetic relatedness was determined by pulsed-field gel electrophoresis. All S. aureus isolates encoded cap5 or cap8. Sixty-nine percent of 2004-2005 isolates were methicillin-susceptible (MSSA) and most expressed a detectable capsule. The majority of MRSA isolates (82%) were unencapsulated, exposing an expressed cell wall techoic acid antigen 336. Pulsed-field type USA300 were MRSA, PVL-positive, unencapsulated strains that were associated with deep skin infections and recurrent disease. Over half (58%) of all isolates from invasive pediatric dermatologic infections were USA300. All pediatric isolates contained either capsule type 5 or capsule type 8 genes, and roughly half of the S. aureus clinical disease isolates from our population were diverse MSSA-encapsulated strains. The majority of the remaining pediatric clinical disease isolates were unencapsulated serotype 336 strains of the PVL(+) USA300 community-associated-MRSA clone.

Epidemiology of viral respiratory tract infections in a prospective cohort of infants and toddlers attending daycare.

BACKGROUND: The epidemiology of respiratory tract infections (RTIs) in a daycare cohort has not been explored using molecular techniques. OBJECTIVES: (1) Determine the overall incidence of RTIs in a daycare cohort using real-time reverse transcriptase polymerase chain reaction (RT-PCR). (2) Determine the relative incidence and impact of specific respiratory viruses, and characterize and compare clinical features associated with these pathogens. STUDY DESIGN: In this prospective cohort study conducted from February 2006 to April 2008, nasal swabs were obtained from symptomatic children ages 0-30 months enrolled in fulltime daycare. RT-PCR was performed to detect respiratory syncytial virus (RSV), human metapneumovirus (MPV), influenza (Flu) viruses A and B, parainfluenza (PIV), adenovirus (AdV), human coronaviruses (CoV) and rhinovirus (RhV). Symptom diaries were completed for each illness. RESULTS: We followed 119 children (mean age 10 months; range 2-24 months) for 115 child years. The mean annual incidence of RTI per child was 4.2 the first year and 1.2 the second year of the study. At least 1 virus was identified in 67% RTIs. Co-infections were common (27% RTIs), with RhV, CoV, and AdV the most common co-pathogens. PIV was identified in 12% of RTIs with a high incidence of PIV4. The viruses with the greatest impact on our population were RSV, RhV and AdV. CONCLUSIONS: Using molecular techniques, viruses were identified in approximately twice as many RTIs as previously reported in a daycare cohort. Infections with newly identified viruses, such as HMPV and CoV subtypes were less frequent and severe than infections with RSV, AdV and RhV.

Mupirocin resistance related to increasing mupirocin use in clinical isolates of methicillin-resistant Staphylococcus aureus in a pediatric population.

We investigated the proportion of methicillin-resistant Staphylococcus aureus (MRSA) isolates from pediatric patients demonstrating mupirocin resistance related to mupirocin use at our institution. No mupirocin resistance was found in 98% of isolates, whereas mupirocin prescriptions increased by 110%. Resistance rates remained low despite the increasing use of mupirocin.

Co-infection of the cotton rat (Sigmodon hispidus) with Staphylococcus aureus and influenza A virus results in synergistic disease.

Bacterial super-infection of influenza patients is the primary cause of excess mortality during influenza pandemics, with Staphylococcus aureus (S. aureus) having the highest fatality rate. The cotton rat (Sigmodon hispidus) is an excellent model for both influenza and S. aureus pathogenesis, and therefore a potential tool to model co-infection. We compared physiologic and pathologic changes in cotton rats infected with both S. aureus and influenza A/Wuhan/359/95 (H3N2), with animals infected with each pathogen alone. Co-infected cotton rats demonstrated significantly higher mortality, lower temperatures on 2 and 3 days post-inoculation (p.i.), higher levels of bacteremia and pulmonary bacterial load 4 days p.i., and worse pathology 7 days p.i. Early indicators of exacerbated disease coincided with higher pulmonary mRNA levels for IL-1beta, IL-6, IL-10 and IFNy, supporting the idea that these may contribute to disease severity. Our results demonstrate that the cotton rat is a good model of influenza and S. aureus co-infection, with increased mortality and hypothermia as well as prolonged bacterial duration indicative of synergistic disease that may be the result of increased induction of both pro- and anti-inflammatory cytokines.