ABSTRACT OF INVITED LECTURES AND ORAL PRESENTATION

FTRP2-02IMMUNOPATHOGENESIS OF EV71,DENGUE, SARS AND NOVEL H1N1INFECTIONSKuender D. YangProfessor & Chair, Department of Medical Research, Chang GungMemorial Hospital at Kaohsiung, and Chang Gung University, TaiwanChanges of global ecology expose humans to novelpathogens for emerging infections arising frommicrobial mutation, vector-borne and/or zoonotictransmission. The authors have encountered andstudied four emerging infections includingenterovirus 71 encephalitis, dengue hemorrhagicfever and severe acute respiratory syndrome (SARS)and novel influenza A (H1N1) in the past decade.Here they described and summarized immunemechanisms of common emerging infections intofour categories: 1) host naïve immunodeficiencywith disseminated infection; 2) earlyimmunosuppression with and without lateraugmented immunity; 3) augmented innate immunitywith vascular insults; and 4) cross-enhancement ofsecondary heterotypic infections. A practical guide toidentify the fatal mechanism of an emerginginfection is described to early diagnose and earlytreat the life-threatening infection. Based on theevolution of common emerging infections, a 4-stepstrategy is formulated for the prevention of apotential emerging infection during pre-outbreak,sporadic early outbreak, endemic outbreak andpandemic outbreak.FTRP2-03COMMUNITY-ASSOCIATEDMETHICILLIN-RESISTANT STAPHYLOCOCCUSAUREUS IN TAIWAN AND THE WORLDYhu-Chering HuangChang Gung Memorial Hospital and Chang Gung University, Kweishan, TaiwanStaphylococcus aureus is an important pathogen in humans and causesa broad spectrum of diseases, ranging from skin and soft tissueinfection to life-threatening infections of septicemia, necrotizingfasciitis, and toxic shock syndrome. Methicillin-resistant S. aureus(MRSA) is usually considered a nosocomial pathogen, and if acquiredin the community, most infections were traditionally confined toindividuals with health care-associated risk factors. However, thechanging epidemiology of MRSA became evident in the 1990s whenMRSA infections occurred in previously healthy children withoutestablished risk factors for MRSA acquisition. The term“community-associated” (CA) MRSA infection was used to describethis disease entity.CA-MRSA was first reported from infections in remote populations inAustralia, and in the USA by the end of the 1990s. Since then, MRSAinfections have also been reported from Europe, the near East, Asia andOceania. CA-MRSA strains have been recognized as a novel pathogenwhich is genetically different from the healthcare-associated (HA)MRSA in the US. They are usually characterized by limited antibioticresistance (except to β-lactams), possess different exotoxin geneprofiles (e.g. Panton-Valentine leukocidin, PVL), carry type IV or Vstaphylococcal cassette chromosome (SCCmec IV, V), and the majorclinical manifestations are usually cellulitis and abscess. However,CA-MRSA clones vary in different continents, countries and evenareas; for example, clones with multilocus sequence types (ST) 1(USA400) and 8 (USA300) are mostly found in the United States andCanada, clones with ST80 are mostly found in Europe, while cloneswith ST30 are found worldwide, including US, Europe, Oceania,Japan. CA-MRSA has become a matter of concern worldwide, inparticular in the USA.In Taiwan, CA-MRSA, though not uncommon, had not drawn anyconcern in 1990s until cases of fatal infections in children werereported in Minnesota and North Dakota in the US. CA-MRSAinfections have been increasingly reported in pediatric patients since2000. The rate of methicillin resistance among CA S. aureus infectionsin children without risk factors increased from 9.8% between 1999 and2000 to 56% between 2004 and 2005. Likewise, the nasal carriage rateof MRSA among previously healthy children increased significantlyfrom 1.9% in 2001 to 10.2% during the period 2007 to 2008. Theincreasing trend of nasal MRSA colonization prevalence might accountfor the increasing incidence of CA-MRSA infection in children inTaiwan. Most CA-MRSA clinical isolates in Taiwan are geneticallydifferent from HA-MRSA isolates and are characterized by ST59 or itsvariant ST338, a specific pulsed-field gel electrophoresis (PFGE)pattern (similar to USA 1000), resistance to clindamycin anderythromycin, containing a specific type of SCCmec (type V T , alsotentatively designated as type VII lately) gene, and possessing PVLgenes.96