siam id board review 2010

8/6/2019 Siam ID Board Review 2010

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Interes'ngTopics

onMicrobiology

DepartmentofMicrobiology

FacultyofMedicine

SirirajHo

spital


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ScopeReviewofbacterial&fungaliden'fica'on

Issueswithdrug-resistantbacteria


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Bacterial & FungalIdentification


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Gram-positive

cocci

ClustersStaphylocccusspp.

Chains

Streptococcusspp.Enterococcusspp.

(Catalase-Pos)Catalase test

H2

O2

H2

O + O2

(+) (-)

(Catalase-Neg)


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Coagulasetest (+)S.aureus(-)CNS

Slidetest

(-)

(+)

Tubetest

(-) (+)

Staphylococci


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Beta-hemolysis

GroupAstreptococci(S.pyogenes)

GroupBstreptococci(S.agalac3ae)

Alpha/gamma-hemolysis

(Non-groupable)S.pneumoniaeViridansstreptococci

Streptococci

Bacitracin-GroupAOptochin-S.pneumo

S.aureus

Posive

CAMP-posive

[GroupBStrep]

Hemolysis

Latex-grouping


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Gram-Positive RodsAerobe / Facultative anaerobe Anaerobe

Spore-former Non-spore-former Spore-former Non-spore-formerBacillus

Coccobacilli

Branching filament

AF negative

MAF positiveMAF negative

AF positiveMycobacteriumListeria

Rhodococcus

Nocardia

Corynebacterium

Actinomyces

Erysipelothrix

Actinomyces

Propionibacterium

Lactobacillus

Clostridium

AF = acid-fast stainMAF = modified AF stain

Pathogenic Bacteria Worksheet 1 By Pattarachai Kiratisin

GardnerellaGram-variablecoccobacilli

Regular rods Coryneform

Ac

tinomycetes

B. anthracis-anthrax (3 forms)-anthrax toxin

B. cereus-Food poisoning

-Enterotoxin

-Intoxication

L. monocytogenes-meningitis

-brain, placenta-CMI defect

E. rhusiopathiae-erysipeloid-occupation

-CMI defect

Slow growerM. tuberculosis

-TB-intracellular

Rapid grower

M. fortuitum comp-skin infection

Uncultivable

M. leprae-leprosy

R. equi-pneumonia-occupation

-CMI defect

C. diphtheriae-diphtheria-diphtheria toxin

G. vaginalis-bacterial vaginosis-clue cell

-Whiffs test

N. asteroides-abscess-CMI defect

A. israelii-mycetoma-tissue abscess

-anaerobe!

C. perfringens-gas gangrene(alpha toxin)

-enteritisnecroticans

(beta toxin)C. difficile-antibiotic-associated

diarrhea

-toxin A & BC. botulinum-botulism-botulinum toxin

C. tetani

-tetanus-tetanus toxin

A. israelii-mycetoma-tissue abscess

P. acnes-skin flora-acne vulgaris

L. rhamnosus-vaginal flora-chorioamnionitis


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Spot Diagnosis


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Gram-negative rodsCoccobacilli

Enterobacteriaceae(Oxidase-neg)

Non-fermenters

Curved rods


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Gram-Negative RodsAerobe / Facultative anaerobe Anaerobe

CoccobacilliRegular rods

Curved rods

Glucose fermenter(Enterobacteriaceae)

Non-fermenter (NF)

Pathogenic Bacteria Worksheet 2

By Pattarachai Kiratisin

Moraxella

Small pleomorphiccoccobacilli

Haemophilus Brucella

Francisella

Pasteurella

Escherichia

Klebsiella

Salmonella

Shigella

Burkholderia

Acinetobacter

Stenotrophomonas

Vibrio

Aeromonas

Plesiomonas

Bacteroides

Porphyromonas

Prevotella

Fusobacterium

Bordetella

MicroaerophileHelicobacter

Campylobacter

Capnocytophaga

Pseudomonas

LegionellaFastidious

M. catarrhalis-pneumonia-acute in COPD

H. influenzae-capsule: Hib-pneumonia

-meningitisH. ducreyi-chancroid

B. pertussis-pertussis-pertussis toxin

B. melitensis-brucellosis-zoonosis

F. tularensis-tularemia

-zoonosisP. multocida-wound infection-zoonosis

E. coli-UTI

-diarrhea-meningitis-several toxins &

adhesins

K. pneumoniae-pneumonia-capsule

S. enterica-typhoid fever-intracellular

S. dysenteriae-enterocolitis

-shiga toxin

L. pneumophila-Legionaires-water, cooler

P. aeruginosa-wound infection-exotoxin A

B. pseudomallei-melioidosis-soil / SEA area

A. baumannii-pneumonia-nosocomial

S. maltophilia-pneumonia

-nosocomial

V. Cholerae-cholera toxin

V. parahaemolyticus

V. vulnificusA. hydrophila

-diarrhea-water reservoir

P. shigelloides

-diarrhea

H. pylori-gastritis-urease

C. jejuni-enterocolitis-animal reservoir

B. fragilis-GI flora-mixed infection

P. gingivalis-oral flora-mixed infection

P. melaninogenica-oral flora-mixed infection

F. nucleatum-oral flora-vincent angina

C. canimorsus-oral flora (dog)-wound infection


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FungiYeast Mold

SmallroundedformBuddingorfission Filamentousform(hyphae/mycelium)

Elongaon


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YeastMold

Hyalinemold

Demaaceousmold

Non-septatehyphaeSeptatehyphae

DimorphicfungiDermatophyteGeneral

Buddingunicellular37c 25c

Fungi


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Spot Diagnosis


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Spot Diagnosis


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Drug-Resistant Bacteria


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MediatedbymecA(PBP2a)

Diskdiffusiontest:cefoxi'nrecommended

(cefoxinonlyforCNS,nooxacillinzone)

Heteroresistance(1:10^6)maybemissed

Full24-hincubaonrequiredfortesng

ReportResistanttoallb-lactams(incld.carbapenems)

&BLBIregardlessoftestresults

MRSA


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MediatedbyvanA

Diskdiffusiontest:notavailable

VancomycinMICbreakpoint=2ug/mL(R,if16)

(forCNS=4ug/mL,Rif32)

hVISA(1:10^6,MIC=4)canbedetectedbyMIC

MIC32cannotbedetectedbydiskdiffusion

Full24-hincubaonrequiredforMICtesng

Report

NeedtoconfirmforMICandvangene

VISA / VRSA


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Erythromycin Clindamycin

Ifposi've(D-zoneor

hazygrowthnearClin),reportclindamycinR

D-zonetest

IfRtoerythromycinandS/Itoclindamycin

Testforstaphylococciandb-hemolycstreptococci

Inducible clindamycin resistance


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Resistancemechanism

Macrolidesonly:Efflux(msrA:staph,mef:strep)

Inducibleclindamycininmacrolide-R:MLSB

(erm:methylaonof23SrRNA)

Inducible clindamycin resistance


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Useoxacillindiskfortes'ng

Zone20mm(=MIC0.06)

-StoPen,Amp,Amp-sul,Cefuroxime,Imi,Mer

Zone19mm

-MustdoMICforPen+Cefo/Ceri/Mer

-AboveMICberounelyreportedforCSFisolate

PGSMICBreakpoint-Meningis=0.06ug/mL

-Non-meningis=2ug/mL

PRSP (Pen-R S.pneumoniae)


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Diskdiffusionnotreliablefor(mustdoMIC):

-Amp,Amox

-Cefuroxime,Ceriaxone,Cefotaxime,Cefepime-Ertapenem,Imipenem,Meropenem

PRSP (Pen-R S.pneumoniae)


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Notrecommendedfortes'ngofgroupsA&B

B-lactamtest:ifclinicalresponseunsasfied

-StoPencoversallapprovedb-lactams

Macrolidetest:ifallergictoPen

-Testforinducibleclindamycinifindicated

Other streptococci

Viridansstreptococci

B-lactamtest:Pendiskmethodnotreliable

-TestMICfromsterilesites


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EnterococciPen/AmpResistance:

-Commonlyduetolow-affinityPBPs

-Rarelyduetob-lactamase

PenS >>>AmpS(noneedtotestAmp)AmpS>>>NeedtotestPenB-lactamasetest-Posi've>>>AllPensR

SynergywithAminoglycosidesifPen/AmpS-NoRtohigh-levelgentamicin/streptomycin


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VREVannon-suscep'blebydisk(I,R)mustdoMIC

Full24-hincubaonrequired

VanMICbreakpoint=4IfMIC8/16(I):confirmidenficaon

E.gallinarum&E.casseliflavus:intrinsic(I)duetoVanC

E.faecium&E.faecalis:acquired(R)duetoVanA/VanB


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Screeningtest:

Cepodoxime(10ug) 17mm,or 22mmforP.mirabilis

Ceazidime(30ug) 22mm,or

Cefotaxime(30ug) 27mm,orCeriaxone(30ug) 25mm(notforP.mirabilis)

ESBLExtended-SpectrumBeta-Lactamase


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Combina'ondisktest(confirmatorytest)

Ceazidime/Ceazidime-clavand

Cefotaxime/Cefotaxime-clav

5-mmincreaseofzonewhencombinedwithclav=ESBL

Non-ESBL ESBL

ESBL


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RounelyforE.coli,K.pneumoniae,K.oxytoca

&clinicalsignificantisolateofP.mirabilis

ReportasRforallpenicillinsandcephalosporins(regardlessofinvitroresults)

ESBL


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Newcephalosporinbreakpoints

Drug MIC Inhibi'onzone

Cefazolin 8/321/4 14/18None!

Cefotaxime 8/641/4 14/2322/26

Ceriaxone 8/641/4 13/2119/23

Ceazidime 8/324/16 14/1817/21

ESBLNewguideline(CLSI2010)


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Hydrolyzeallb-lactamsincludingcarbapenems

Klebsiellapneumoniaecarbapenemase

Screening

Zonediameter MIC

Ertapenem 19-21mm(S19)2

Meropenem16-21mm(S16) 2-4

Imipenem *Performpoorly 2-4

KPC


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LawnofE.coliATCC25922

Ertapenem/meropenemdisk

(10ug)

Testisolates

Confirmatorytest:ModifiedHodgeTest

KPC


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Report

IfMHT+buttestedStocarbapenems:ReportcarbapenemMICwithoutinterpretaonWithnoficaon

carbapenemaseproduconwasdemonstrated:

noestablishedclinicalefficacyofcarbapenemsfor

treatment

IfIorRtocarbapenems,noneedtodoMHT

KPC


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Resistant to penicillins andmost cephalosporins

(includingcephamycins)

Susceptible to cefepime, cefpirome andcarbapenems

Notinhibitedbyclavulanicacid

Chromosomal&plasmid-mediated

AmpC b-lactamase

Note:Bolded=differentfromESBL


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Beta-lactamasesMolecularclass Ac'vesite Member

A Serine ESBL,KPC,

mostpenicillinases&

cephalosporinases

B Zinc Metallo-b-lactamase

(VIM,IMP)

C Serine AmpC

D Serine OXA


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PseudomonasaeruginosaResistancemechanisms

Mechanism Effect

IncreasedAmpC Ceph&an-pseudomonalPen

(HyperproduconaffectsImi,notMer)

MexAB-OprM

(Cons.Expr.)

Ceph&an-pseudomonalPen

FQ,Tet,Chloram,Mer&Erta(notImi)

MexCD-OprJMexXY-OprM* Pip(notCarben),Cefepime(notCeaz),FQ,Mer&Erta(notImi),*alsoAG

MexEF-OprN FQ,Trimethoprim,Chloram

Porin(OprD)loss Imi(lessforMer,notErta)

Metallo-b-lactamase Allb-lactams


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AcinetobacterbaumanniiResistancemechanisms(*Intrinsic)

Mechanism Effect

AmpC* 3GCeph(hyperproducon)

ESBL,OXA,metallo- Ceph,Carbapenems

PBPchange* Pen&Ceph

AdeABCefflux* Ceph,Tigecycline

FQ(highRwithgyrA/parCmutaon&porinloss)

AbeMefflux FQ,AG

Tetefflux(TetA,B) Tet,Mino

Porin(CarO)loss* Ceph

Membranealter* Colisn,PolymyxinB


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BLNAR H. influenzae

CSFisolate:

-ReportonlyAmp,a3GC,Mero,Chloram

Beta-LactamaseNegave,AmpicillinResistance

R toAmox-clav,Amp-sul,Pip-tazo&Cefuroxime(regardlessofinvitroresults)B-lactamasetestposi've:RtoAmp&Amox

-B-lactamasetestrequiredforallisolates


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DaptomycinDivalentca'ons(Ca2+)

-Insufficience:causefalse-resistance

Onlysuscepblebreakpoint[noI/R]available:-Staphylococci&streptococci,notS.pneumoniae(1)

-Enterococci(4)

*Diskdiffusionmethodnotreliable

Issues with Some Antibacterial AgentsDoripenem

NoCLSIguidelinefortes'ng&interpreta'on


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Colis'nCLSIguideline

-DiskmethodonlyavailableforP.aeruginosa

-MICmethodavailableforP.aeruginosa&

Acinetobacterspp.

MICbreakpoint

-P.aeruginosa:[S]2/[I]=4/[R]8

-Acinetobacter:[S]2/no[I]/[R]4

Issues with Some Antibacterial Agents


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TigecyclineNoCLSIguideline

-Issueswithcaonse.g.Mn2+

Medium

(Mnconcentra'ons)

Medium1

(2.5ug/mL)

Medium2

(2.5ug/mL)

Medium3

(629ug/mL)

A.baumanniiMIC50

MIC90

0.5

1

1.5

2

4

4

ESBL(+)E.coliMIC50

MIC90

0.38

0.75

0.5

1

2

3

ESBL(+)K.pneumoniaeMIC50

MIC90

0.75

1.5

1

1

2

4

Issues with Some Antibacterial Agents


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siam id board review 2010

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