Polymicrobial acute respiratory infections in a hospital-based pediatric population.

BACKGROUND: The clinical impact of polymicrobial respiratory infections remains uncertain. Previous reports are contradictory regarding an association with severe disease. METHODS: Three hundred forty-six specimens from children with acute respiratory illness identified at the University of Iowa Hospitals and Clinics Clinical Microbiology Laboratory were evaluated by direct immunofluorescent assay and/or viral culture by Clinical Microbiology Laboratory and later by molecular study for the presence of influenza, parainfluenza, respiratory syncytial virus, adenovirus, human metapneumovirus, rhinovirus and human bocavirus. Demographic and clinical data were abstracted from medical records. RESULTS: Multiple viruses were detected in 46 (21.7%) of 212 virus-positive specimens with the most frequent virus-virus combinations being HRV-respiratory syncytial virus (n = 12), HRV-human bocavirus (n = 6) and HRV-parainfluenza virus 3 (n = 4). Risk factors for coinfection included male gender (OR [odds ratio]: 1.70, 95% confidence interval [CI]: 0.83-3.46), 6 months to 1 year age (OR: 2.15, 95% CI: 0.75-6.19) and history of immunosuppression (OR: 2.05, 95% CI: 0.99-4.23). Children with viral coinfections were less likely than children with single virus infections to be admitted to an intensive care unit (OR: 0.32, 95% CI: 0.08-1.27); however, this may be explained by undetected viral-bacterial coinfections. CONCLUSIONS: HRV, respiratory syncytial virus, human bocavirus, and polymicrobial infections were prevalent in this study. Although the cross-sectional design could not easily examine polymicrobial infection and disease severity, prospective, population-based research regarding the clinical impact of such infections is warranted.

MChip, a low density microarray, differentiates among seasonal human H1N1, North American swine H1N1, and the 2009 pandemic H1N1.

BACKGROUND: The MChip uses data from the hybridization of amplified viral RNA to 15 distinct oligonucleotides that target the influenza A matrix (M) gene segment. An artificial neural network (ANN) automates the interpretation of subtle differences in fluorescence intensity patterns from the microarray. The complete process from clinical specimen to identification including amplification of viral RNA can be completed in <8 hours for under US$10. OBJECTIVES: The work presented here represents an effort to expand and test the capabilities of the MChip to differentiate influenza A/H1N1 of various species origin. METHODS: The MChip ANN was trained to recognize fluorescence image patterns of a variety of known influenza A viruses, including examples of human H1N1, human H3N2, swine H1N1, 2009 pandemic influenza A H1N1, and a wide variety of avian, equine, canine, and swine influenza viruses. Robustness of the MChip ANN was evaluated using 296 blinded isolates. RESULTS: Training of the ANN was expanded by the addition of 71 well-characterized influenza A isolates and yielded relatively high accuracy (little misclassification) in distinguishing unique H1N1 strains: nine human A/H1N1 (88·9% correct), 35 human A/H3N2 (97·1% correct), 31 North American swine A/H1N1 (80·6% correct), 14 2009 pandemic A/H1N1 (87·7% correct), and 23 negative samples (91·3% correct). Genetic diversity among the swine H1N1 isolates may have contributed to the lower success rate for these viruses. CONCLUSIONS: The current study demonstrates the MChip has the capability to differentiate the genetic variations among influenza viruses with appropriate ANN training. Further selective enrichment of the ANN will improve its ability to rapidly and reliably characterize influenza viruses of unknown origin.

Emergent US adenovirus 3 strains associated with an epidemic and serious disease.

BACKGROUND: Adenovirus type 3 (HAdV3) is one of the most prevalent serotypes detected globally. Variants of HAdV3 have been associated with outbreaks of severe disease. OBJECTIVES: To better understand genetic diversity of circulating HAdV3s and examine risk factors for severe disease. STUDY DESIGN: Restriction enzyme analysis for genomic characterization of clinical HAdV3 isolates detected by 15 collaborative US laboratories during the period July 2004 to May 2007. Multivariate modeling was employed for statistical analyses. RESULTS: The most common HAdV3 types of 516 isolates studied were HAdV3a2 (36.9%), HAdV3a50 (27.1%), HAdV3a51 (18.0%), and HAdV3a17 (4.6%). Non-HAdV3a genome types were rare (1.2%). HAdV3a50 and HAdV3a51 are newly described variants which became more prevalent in 2006 and 2007 and have been associated with at least one epidemic. Their uniqueness was determined by specific banding profiles generated by digests with endonucleases BclI, BglII, and HindIII. Multivariable risk factor modeling demonstrated that children under 2 years of age (OR=2.7; 95%CI 1.6-4.6), persons with chronic disease (OR=5.1; 95%CI 2.6-9.8), persons infected with HAdV3a2 (OR=3.0; 95%CI 1.5-6.0), with HAdV3a50 (OR=2.5; 95%CI 1.2-5.2), or with multiple or rare strains (OR=2.8; 95%CI 1.3-6.5) were at increased risk of severe HAdV3 clinical disease. CONCLUSIONS: In the study period considerable genetic diversity was found among US clinical HAdV3 strains. Novel variants emerged and became prevalent. One such emergent strain may be associated with more severe clinical disease.

Molecular typing of clinical adenovirus specimens by an algorithm which permits detection of adenovirus coinfections and intermediate adenovirus strains.

BACKGROUND: Epidemiological data suggest that clinical outcomes of human adenovirus (HAdV) infection may be influenced by virus serotype, coinfection with multiple strains, or infection with novel intermediate strains. In this report, we propose a clinical algorithm for detecting HAdV coinfection and intermediate strains. STUDY DESIGN: We PCR amplified and sequenced subregions of the hexon and fiber genes of 342 HAdV-positive clinical specimens obtained from 14 surveillance laboratories. Sequences were then compared with those from 52 HAdV prototypic strains. HAdV-positive specimens that showed nucleotide sequence identity with a corresponding prototype strain were designated as being of that strain. When hexon and fiber gene sequences disagreed, or sequence identity was low, the specimens were further characterized by viral culture, plaque purification, repeat PCR with sequencing, and genome restriction enzyme digest analysis. RESULTS: Of the 342 HAdV-positive clinical specimens, 328 (95.9%) were single HAdV strain infections, 12 (3.5%) were coinfections, and 2 (0.6%) had intermediate strains. Coinfected specimens and intermediate HAdV strains considered together were more likely to be associated with severe illness compared to other HAdV-positive specimens (OR=3.8; 95% CI=1.2-11.9). CONCLUSIONS: The majority of severe cases of HAdV illness cases occurred among immunocompromised patients. The analytic algorithm we describe here can be used to screen clinical specimens for evidence of HAdV coinfection and novel intermediate HAdV strains. This algorithm may be especially useful in investigating HAdV outbreaks and clusters of unusually severe HAdV disease.

Adenovirus type 3 outbreak in connecticut associated with a novel variant.

An adenovirus outbreak occurred in New Haven, Connecticut in 2006-2007. Molecular typing revealed a twofold increase in adenovirus type 3 infections. Restriction enzyme analysis (REA) indicated that the CT outbreak was largely due to a marked increase in the novel Ad3a51 strain. This outbreak represents the first detection of Ad3a51 in the United States. While most infections were mild, children under 3 were at increased risk for severe disease and one patient with underlying disease died.

Evidence for avian influenza A infections among Iowa's agricultural workers.

BACKGROUND: Identifying risk factors for zoonotic influenza transmission may aid public health officials in pandemic influenza planning. OBJECTIVES: We sought to evaluate rural Iowan agriculture workers exposed to poultry for previous evidence of avian influenza virus infection. METHODS: In 2004 we enrolled 803 rural adult Iowans in a 2-year prospective study of zoonotic influenza transmission. Their enrollment data and sera were compared with those from 66 adult controls enrolled at the University of Iowa in 2006 by proportional odds modeling. RESULTS: The 803 participants were 58.8% male with a mean age of 55.6 yrs. Forty-eight percent reported previous poultry exposure. Sera were studied by microneutralization techniques for antibodies against avian H4, H5, H6, H7, and H9 viruses. Touching live birds was associated (OR = 1.2; 95% CI 1.02-1.8) with increased antibody titer against H5 virus. Similarly, participants who reported hunting wild birds had increased antibody titers against H7 virus (OR = 2.8; 95%CI = 1.2-6.5) and subjects who reported recent work with poultry had increased antibody titers against H6 (OR = 3.4; 95% CI 1.4-8.5) and H7 viruses (OR = 2.5, 95% CI = 1.1-5.7). There was no evidence of elevated antibody against avian H4 or H9 viruses. CONCLUSIONS: These data suggest that hunting and exposure to poultry may be important risk factors for avian influenza virus infection among rural US populations. Agriculture workers should be included in influenza pandemic plans.

Genotype prevalence and risk factors for severe clinical adenovirus infection, United States 2004-2006.

BACKGROUND: Recently, epidemiological and clinical data have revealed important changes with regard to clinical adenovirus infection, including alterations in antigenic presentation, geographical distribution, and virulence of the virus. METHODS: In an effort to better understand the epidemiology of clinical adenovirus infection in the United States, we adopted a new molecular adenovirus typing technique to study clinical adenovirus isolates collected from 22 medical facilities over a 25-month period during 2004-2006. A hexon gene sequence typing method was used to characterize 2237 clinical adenovirus-positive specimens, comparing their sequences with those of the 51 currently recognized prototype human adenovirus strains. In a blinded comparison, this method performed well and was much faster than the classic serologic typing method. RESULTS: Among civilians, the most prevalent adenovirus types were types 3 (prevalence, 34.6%), 2 (24.3%), 1 (17.7%), and 5 (5.3%). Among military trainees, the most prevalent types were types 4 (prevalence, 92.8%), 3 (2.6%), and 21 (2.4%). CONCLUSIONS: For both populations, we observed a statistically significant increasing trend of adenovirus type 21 detection over time. Among adenovirus isolates recovered from specimens from civilians, 50% were associated with hospitalization, 19.6% with a chronic disease condition, 11% with a bone marrow or solid organ transplantation, 7.4% with intensive care unit stay, and 4.2% with a cancer diagnosis. Multivariable risk factor modeling for adenovirus disease severity found that age <7 years (odds ratio [OR], 3.2; 95% confidence interval [CI], 1.4-7.4), chronic disease (OR, 3.6; 95% CI, 2.6-5.1), recent transplantation (OR, 2.7; 95% CI, 1.3-5.2), and adenovirus type 5 (OR, 2.7; 95% CI, 1.5-4.7) or type 21 infection (OR, 7.6; 95% CI, 2.6-22.3) increased the risk of severe disease.

11-Beta hydroxysteroid dehydrogenase type 2 in human adult and fetal lung and its regulation by sex steroids.

11-Beta hydroxysteroid dehydrogenase type 2 (HSD2) oxidizes the biologically active glucocorticoid (GC), cortisol, to inactive cortisone. We characterized HSD2 gene expression and activity in human adult and fetal lung tissues and in cultured fetal lung explants, and examined the potential regulation of HSD2 in the fetal lung by sex steroids. Human adult lung, fetal lung, and cultured fetal lung explant tissues contained similar amounts of HSD2 mRNA. However, higher levels of HSD2 protein were detected in human fetal lung tissue than in adult lung, with expression being restricted to a subset of epithelial cells in the fetal lung tissue. Differentiated fetal lung explants maintained in culture expressed higher levels of HSD2 protein and enzymatic activity than undifferentiated fetal lung tissues. Finally, HSD2 protein levels were decreased in male, but not female, fetal lung explants treated with 17-beta estradiol. In contrast, 5-alpha dihydrotestosterone did not significantly affect HSD2 levels. These data indicate that HSD2 protein and activity levels increase in parallel with the differentiation of alveolar type II epithelial cells in vitro, and that HSD2 protein levels are regulated by 17-beta estradiol in male fetal lung tissue.

Swine workers and swine influenza virus infections.

In 2004, 803 rural Iowans from the Agricultural Health Study were enrolled in a 2-year prospective study of zoonotic influenza transmission. Demographic and occupational exposure data from enrollment, 12-month, and 24-month follow-up encounters were examined for association with evidence of previous and incident influenza virus infections. When proportional odds modeling with multivariable adjustment was used, upon enrollment, swine-exposed participants (odds ratio [OR] 54.9, 95% confidence interval [CI] 13.0-232.6) and their nonswine-exposed spouses (OR 28.2, 95% CI 6.1-130.1) were found to have an increased odds of elevated antibody level to swine influenza (H1N1) virus compared with 79 nonexposed University of Iowa personnel. Further evidence of occupational swine influenza virus infections was observed through self-reported influenza-like illness data, comparisons of enrollment and follow-up serum samples, and the isolation of a reassortant swine influenza (H1N1) virus from an ill swine farmer. Study data suggest that swine workers and their nonswine-exposed spouses are at increased risk of zoonotic influenza virus infections.

Human metapneumovirus, Peru.

We retrospectively studied 420 pharyngeal swab specimens collected from Peruvian and Argentinean patients with influenzalike illness in 2002 and 2003 for evidence of human metapneumovirus (HMPV). Twelve specimens (2.3%) were positive by multiple assays. Six specimens yielded HMPV isolates. Four of the 6 isolates were of the uncommon B1 genotype.

Antisense inhibition of surfactant protein A decreases tubular myelin formation in human fetal lung in vitro.

Surfactant protein A (SP-A) is the most abundant of the surfactant-associated proteins. SP-A is involved in the formation of tubular myelin, the modulation of the surface tension-reducing properties of surfactant phospholipids, the metabolism of surfactant phospholipids, and local pulmonary host defense. We hypothesized that elimination of SP-A would alter the regulation of SP-B gene expression and the formation of tubular myelin. Midtrimester human fetal lung explants were cultured for 3-5 days in the presence or absence of an antisense 18-mer phosphorothioate oligonucleotide (ON) complementary to SP-A mRNA. After 3 days in culture, SP-A mRNA was undetectable in antisense ON-treated explants. After 5 days in culture, levels of SP-A protein were also decreased by antisense treatment. SP-B mRNA levels were not affected by the antisense SP-A ON treatment. However, there was decreased tubular myelin formation in the antisense SP-A ON-treated tissue. We conclude that selective elimination of SP-A mRNA and protein results in a decrease in tubular myelin formation in human fetal lung without affecting SP-B mRNA. We speculate that SP-A is critical to the formation of tubular myelin during human lung development and that the regulation of SP-B gene expression is independent of SP-A gene expression.