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Volume 16, Number 4—April 2010

Volume 16, Number 4—April 2010   PDF Version [PDF - 5.32 MB - 175 pages]


  • Livestock-associated Methicillin-Resistant Staphylococcus aureus Sequence Type 398 in Humans, Canada PDF Version [PDF - 387 KB - 8 pages]
    G. R. Golding et al.
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    Rates of colonization with livestock-associated methicillin-resistant Staphylococcus aureus (MRSA) sequence type 398 have been high for pigs and pig farmers in Canada, but prevalence rates for the general human population are unknown. In this study, 5 LA-MRSA isolates, 4 of which were obtained from skin and soft tissue infections, were identified from 3,687 tested MRSA isolates from persons in Manitoba and Saskatchewan, Canada. Further molecular characterization determined that these isolates all contained staphylococcal cassette chromosome (SCC) mecV, were negative for Panton-Valentine leukocidin, and were closely related by macrorestriction analysis with the restriction enzyme Cfr91. The complete DNA sequence of the SCCmec region from the isolate showed a novel subtype of SCCmecV harboring clustered regularly interspaced short palindromic repeats and associated genes. Although prevalence of livestock-associated MRSA seems to be low for the general population in Canada, recent emergence of infections resulting from this strain is of public health concern.

  • Influenza A Strain-Dependent Pathogenesis in Fatal H1N1 and H5N1 Subtype Infections of Mice PDF Version [PDF - 739 KB - 9 pages]
    M. Garigliany et al.
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    To determine if fatal infections caused by different highly virulent influenza A viruses share the same pathogenesis, we compared 2 different influenza A virus subtypes, H1N1 and H5N1. The subtypes, which had shown no pathogenicity in laboratory mice, were forced to evolve by serial passaging. Although both adapted viruses evoked diffuse alveolar damage and showed a similar 50% mouse lethal dose and the same peak lung concentration, each had a distinct pathologic signature and caused a different course of acute respiratory distress syndrome. In the absence of any virus labeling, a histologist could readily distinguish infections caused by these 2 viruses. The different histologic features described in this study here refute the hypothesis of a single, universal cytokine storm underlying all fatal influenza diseases. Research is thus crucially needed to identify sets of virulence markers and to examine whether treatment should be tailored to the influenza virus pathotype.

  • Clostridium difficile Infections among Hospitalized Children, United States, 1997–2006 PDF Version [PDF - 287 KB - 6 pages]
    M. D. Zilberberg et al.
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    We evaluated the annual rate (cases/10,000 hospitalizations) of pediatric hospitalizations with Clostridium difficile infection (CDI; International Classification of Diseases, 9th revision, clinical modification code 008.45) in the United States. We performed a time-series analysis of data from the Kids’ Inpatient Database within the Health Care Cost and Utilization Project during 1997–2006 and a cross-sectional analysis within the National Hospital Discharge Survey during 2006. The rate of pediatric CDI-related hospitalizations increased from 7.24 to 12.80 from 1997 through 2006; the lowest rate was for children <1 year of age. Although incidence was lowest for newborns (0.5), incidence for children <1 year of age who were not newborns (32.01) was similar to that for children 5–9 years of age (35.27), which in turn was second only to incidence for children 1–4 years of age (44.87). Pediatric CDI-related hospitalizations are increasing. A better understanding of the epidemiology and outcomes of CDI is urgently needed.

  • Phylogenetic Analysis of Enterohemorrhagic Escherichia coli O157, Germany, 1987–2008 PDF Version [PDF - 262 KB - 7 pages]
    C. Jenke et al.
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    Multilocus variable number tandem repeat analysis (MLVA) is a subtyping technique for characterizing human pathogenic bacteria such as enterohemorrhagic Escherichia coli (EHEC) O157. We determined the phylogeny of 202 epidemiologically unrelated EHEC O157:H7/H clinical isolates through 8 MLVA loci obtained in Germany during 1987–2008. Biodiversity in the loci ranged from 0.66 to 0.90. Four of 8 loci showed null alleles and a frequency <44.1%. These loci were distributed among 48.5% of all strains. Overall, 141 MLVA profiles were identified. Phylogenetic analysis assigned 67.3% of the strains to 19 MLVA clusters. Specific MLVA profiles with an evolutionary persistence were identified, particularly within sorbitol-fermenting EHEC O157:H.These pathogens belonged to the same MLVA cluster. Our findings indicate successful persistence of this clone.

  • Use of Norovirus Genotype Profiles to Differentiate Origins of Foodborne Outbreaks PDF Version [PDF - 208 KB - 8 pages]
    L. Verhoef et al.
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    Because secondary transmission masks the connection between sources and outbreaks, estimating the proportion of foodborne norovirus infections is difficult. We studied whether norovirus genotype frequency distributions (genotype profiles) can enhance detection of the sources of foodborne outbreaks. Control measures differ substantially; therefore, differentiating this transmission mode from person-borne or food handler–borne outbreaks is of public health interest. Comparison of bivalve mollusks collected during monitoring (n = 295) and outbreak surveillance strains (n = 2,858) showed 2 distinguishable genotype profiles in 1) human feces and 2) source-contaminated food and bivalve mollusks; genotypes I.2 and I.4 were more frequently detected in foodborne outbreaks. Overall, ≈21% of all outbreaks were foodborne; further analysis showed that 25% of the outbreaks reported as food handler–associated were probably caused by source contamination of the food.

  • Reassortment of Human Rotavirus Gene Segments into G11 Rotavirus Strains PDF Version [PDF - 203 KB - 6 pages]
    J. Matthijnssens et al.
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    G11 rotaviruses are believed to be of porcine origin. However, a limited number of G11 rotaviruses have been recently isolated from humans in combination with P[25], P[8], P[6], and P[4]. To investigate the evolutionary relationships of these strains, we analyzed the complete genomes of 2 human G11P[25] strains, 2 human G11P[8] strains, and 3 porcine reference strains. Most of the 11 gene segments of these 7 strains belonged to genotype 1 (Wa-like). However, phylogenetic clustering patterns suggested that an unknown G11P[25] strain with a new I12 VP6 genotype was transmitted to the human population, in which it acquired human genotype 1 gene segments through reassortment, resulting in a human G11P[8] rotavirus strain with an entire human Wa-genogroup backbone. This Wa-like backbone is believed to have caused the worldwide spread of human G9 and G12 rotaviruses. G11 human rotavirus strains should be monitored because they may also become major human pathogens.

  • Household Transmission of Pandemic (H1N1) 2009, San Antonio, Texas, USA, April–May 2009 PDF Version [PDF - 253 KB - 7 pages]
    O. W. Morgan et al.
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    To assess household transmission of pandemic (H1N1) 2009 in San Antonio, Texas, USA, during April 15–May 8, 2009, we investigated 77 households. The index case-patient was defined as the household member with the earliest onset date of symptoms of acute respiratory infection (ARI), influenza-like illness (ILI), or laboratory-confirmed pandemic (H1N1) 2009. Median interval between illness onset in index and secondary case-patients was 4 days (range 1–9 days); the index case-patient was likely to be <18 years of age (p = 0.034). The secondary attack rate was 4% for pandemic (H1N1) 2009, 9% for ILI, and 13% for ARI. The secondary attack rate was highest for children <5 years of age (8%–19%) and lowest for adults >50 years of age (4%–12%). Early in the outbreak, household transmission primarily occurred from children to other household members and was lower than the transmission rate for seasonal influenza.

  • Escherichia albertii in Wild and Domestic Birds PDF Version [PDF - 847 KB - 9 pages]
    J. L. Oaks et al.
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    Escherichia albertii has been associated with diarrhea in humans but not with disease or infection in animals. However, in December 2004, E. albertii was found, by biochemical and genetic methods, to be the probable cause of death for redpoll finches (Carduelis flammea) in Alaska. Subsequent investigation found this organism in dead and subclinically infected birds of other species from North America and Australia. Isolates from dead finches in Scotland, previously identified as Escherichia coli O86:K61, also were shown to be E. albertii. Similar to the isolates from humans, E. albertii isolates from birds possessed intimin (eae) and cytolethal distending toxin (cdtB) genes but lacked Shiga toxin (stx) genes. Genetic analysis of eae and cdtB sequences, multilocus sequence typing, and pulsed-field gel electrophoresis patterns showed that the E. albertii strains from birds are heterogeneous but similar to isolates that cause disease in humans.

  • Medscape CME Activity
    Community-associated Methicillin-Resistant Staphylococcus aureus Strains in Pediatric Intensive Care Unit PDF Version [PDF - 351 KB - 9 pages]
    A. M. Milstone et al.
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    Virulent community-associated methicillin-resistant Staphylococcus-aureus (CA-MRSA) strains have spread rapidly in the United States. To characterize the degree to which CA-MRSA strains are imported into and transmitted in pediatric intensive care units (PICU), we performed a retrospective study of children admitted to The Johns Hopkins Hospital PICU, March 1, 2007–May 31, 2008. We found that 72 (6%) of 1,674 PICU patients were colonized with MRSA. MRSA-colonized patients were more likely to be younger (median age 3 years vs. 5 years; p = 0.02) and African American (p<0.001) and to have been hospitalized within 12 months (p<0.001) than were noncolonized patients. MRSA isolates from 66 (92%) colonized patients were fingerprinted; 40 (61%) were genotypically CA-MRSA strains. CA-MRSA strains were isolated from 50% of patients who became colonized with MRSA and caused the only hospital-acquired MRSA catheter-associated bloodstream infection in the cohort. Epidemic CA-MRSA strains are becoming endemic to PICUs, can be transmitted to hospitalized children, and can cause invasive hospital-acquired infections. Further appraisal of MRSA control is needed.

  • Contribution of Streptococcus anginosus to Infections Caused by Groups C and G Streptococci, Southern India PDF Version [PDF - 307 KB - 8 pages]
    S. Reißmann et al.
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    Vellore, a region in southern India, has a high incidence of severe human infections with β-hemolytic group C and G streptococci (GCGS). To determine the causative species in these infections, we conducted 16S rRNA gene sequencing: Streptococcus dysgalactiae subsp. equisimilis (81%) and S. anginosus (19%) were the causative organisms in the 2-year study period (2006–2007). We used PCR to detect the virulence-related emm gene; results showed that it was restricted to S. dysgalactieae subsp. equisimilis isolates of 99.2% tested positive. Due to a novel marker, S. anginosus and S. constellatus can be quickly and accurately distinguished from other members of the genus. The notable contribution of the anginosus group to human infections suggests that this group of obligate pathogens deserves more attention in healthcare and research.

Historical Review

  • Alfred Russel Wallace and the Antivaccination Movement in Victorian England PDF Version [PDF - 219 KB - 5 pages]
    T. P. Weber
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    Alfred Russel Wallace, eminent naturalist and codiscoverer of the principle of natural selection, was a major participant in the antivaccination campaigns in late 19th-century England. Wallace combined social reformism and quantitative arguments to undermine the claims of provaccinationists and had a major impact on the debate. A brief account of Wallace’s background, his role in the campaign, and a summary of his quantitative arguments leads to the conclusion that it is unwarranted to portray Victorian antivaccination campaigners in general as irrational and antiscience. Public health policy can benefit from history, but the proper context of the evidence used should always be kept in mind.



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