FastidiousGramNegativeRodsUNMCHome挑剔的革兰阴性杆菌内布拉斯加大学医学中心的家庭

1、Fastidious Gram Negative RodsBlood Culture UnitDivision of Medical TechnologyCarol Larson MSEd, MT(ASCP)Please click audio iconto hear Carols narration Fastidious Complex / extensive nutrient requirements Faint staining Gram Negative Rods Safranin counterstain for 2 minutes Substitute carbolfuschin

2、for safranin Serological testing usefulClick icon for audioGeneral InformationBrucella speciesClinical Significance Causes Brucellosis / Undulant fever / Malta fever Transmission via: Direct contact with infected animals Ingestion of contaminated meat or dairy products Inhalation of the aerosolized

3、organism Facultative intracellular organism Click icon for audio Blood, bone marrow or tissue Risk of lab acquired infection Specify on requisition when suspecting Brucella BAP, CHOC, BCYE, Blood Culture brothClick icon for audioBrucella speciesSpecimen Collection 35C, 5-10% CO2 for 21 days Colony m

4、orphology Growth at 7 days BAP = smooth glistening, translucent colonies that become brown with ageClick icon for audioBrucella speciesGrowth Characteristics Gram stain: tiny, faint staining gram negative coccobacilli Oxidase +, Catalase + Nitrate + Glucose oxidizer Nonmotile Additional tests to spe

5、ciateClick icon for audioBrucella speciesIdentification Tube agglutination test Single titer of =1:160 Fourfold rise in titer between acute and convalescent specimens Does not detect Brucella canisClick icon for audioBrucella speciesSerological Testing Doxycycline and rifampin for 6 weeksClick icon

6、for audioBrucella speciesTreatment and PreventionHow long must cultures be held when Brucella is suspected?Culture plates and media must be held for at least 21 days because Brucella is a slow grower. Normal flora of mouth, respiratory & GI tracts Opportunistic pathogen Associated with: Dental /

7、 periodontal and head / neck infections / abscesses Human bite wounds Septicemia following tooth extraction EndocarditisClick icon for audioEikenella corrodensClinical SignificanceEikenella corrodensSpecimen Collection Aerobic Requires hemin BAP, CHOCClick icon for audio Tiny colonies at 48 hrs Colo

8、ny morphology BAP “Pits the agar Pale yellow pigment Greening around colony Bleach odor MAC no growthClick icon for audioEikenella corrodensGrowth CharacteristicsEikenella corrodensIdentification Small, slender Gram Negative Bacilli Oxidase + Catalase Glucose non-oxidizer (asaccharolytic) Nitrate +

9、NonmotileClick icon for audio Susceptibility testing not routinely done Treat with: Penicillins 3rd generation cephalosporins Tetracycline QuinolonesClick icon for audioEikenella corrodensTreatment and PreventionWhat are the key identifying characteristics for Eikenella corrodens?It pits the agar an

10、d has a bleach smell on BAP at 48 hours, it will not grow on MAC, it is oxidase positive, catalase negative, glucose N“F”/N“O”, and nitrate positive.Haemophilus aphrophilusActinobacillus actinomycetemcomitansCardiobacterium hominisEikenella corrodensKingella kingae Click icon for audioHACEK GroupOrg

11、anisms Subacute bacterial endocarditis Blood Cultures Subculture to various enriched media and hold for extended time beyond 1 week BCYEClick icon for audioHACEK GroupClinical SignificanceWhat organisms are included in the HACEK group?Haemophilus aphrophilusActinobacillus actinomycetemcomitansCardio

12、bacterium hominisEikenella corrodensKingella kingae Looked at several organisms Clinical significance Specimen collection, transport & processing Growth characteristics & identification Serological testing Treatment and preventionClick icon for audioFastidious GNRSummaryWho am I?BAP, growth

13、appears at 7 daysGram StainBrucella speciesCauses Undulant Fever Doxycycline and rifampin for 6 weeksClick icon for audioBrucella speciesTreatment and Prevention Susceptibility testing not routinely done Treat with: Penicillins 3rd generation cephalosporins Tetracycline QuinolonesClick icon for audioEikenella corrodens