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ID24 Infectious Diseases
Systemic Infections Toronto Notes 2019
• StreptococcalTSS
■ sBP <90 mmHg
■ isolation of GAS from a normally sterile site (e.g. blood, pleural, tissue biopsy, or surgical wound) ■ ≥2 of coagulopathy, liver involvement, ARDS, soft tissue necrosis (necrotizing fasciitis, myositis,
gangrene), renal impairment, erythematous macular rash that may desquamate
Treatment
• supportivecare,fluidresuscitation,surgicaldebridementofinfectedtissue
• Streptococcal:IVpenicillinandclindamycinand±IVIg
• Staphylococcal:formethicillin-susceptibleS.aureus:clindamycin+cloxacillin(IV);forMRSA:
clindamycin + vancomycin x 10-14 d
Cat Scratch Disease
Etiology
• Bartonellahenselae:intracellularbacteria
• cat-to-humantransmissionviacatscratch/bite
Clinical Presentation
• skinlesionappears3-10dpost-inoculation
• maybefollowedbyfever,tenderregionallymphadenopathy
• insomepatients,organismmaydisseminatecausingfeverofunknownorigin,hepatosplenomegaly,
retinitis, encephalopathy, infective endocarditis, uveitis • usuallyself-limited
Investigations
• serology,PCR,lymphnodebiopsy
Treatment
• thediseasemaybeself-limitedbuttreatmentisrecommendedbytheInfectiousDiseaseSocietyof America with a 5 d course of azithromycin for immunocompetent patients with mild to moderate illness
• needleaspirationofpainfulsuppurativelymphnodesmayhastenthereliefofsymptoms
• combinationtherapyconsistingofdoxycyclineorazithromycinplusrifampinoftenusedfor
disseminated disease (neuroterinitis, hepatosplenic involvement)
Rocky Mountain Spotted Fever
Etiology
• Rickettsiarickettsii:obligateintracellularGram-negativeorganism
• reservoirhosts:rodents,dogs
• vectors:Dermacentorticks
• organismscauseinflammationofendothelialliningofsmallbloodvessels,leadingtosmall
hemorrhages and thrombi
• cancausewidespreadvasculitisleadingtoheadache,andCNSchanges;canprogresstodeathif
treatment is delayed
Clinical Presentation
• usuallyoccursinsummerfollowingtickbite
• influenza-likeprodrome:acuteonsetfever,headache,myalgia,nausea/vomiting,anorexia • macularrashappearingonday2-4offever
■ begins on wrists and ankles, then spreads centrally to arms/legs/trunk/palms/soles ■ occasionally “spotless” (10% of patients)
Investigations
• skinbiopsyandserology(indirectfluorescentantibodytest)
Treatment
• doxycycline,usually5-7d(treatfor3dafterdefervescence)
West Nile Virus
Epidemiology
• virushasbeendetectedthroughouttheUnitedStatesandmuchofsouthernCanada(OntarioandManitoba) • overallcase-fatalityratesinseverecasesis~10%
Transmission
• primarilyfrommosquitoesthathavefedoninfectedbirds(crows,bluejays) • transplacental,bloodproducts(rare),organtransplantation