Gram positive cocci Flashcards

1
Q

Staph aureus properties

A
Catalase (+) 
 coagulase (+)
Mannitol fermentation (+) 
Phosphatase (+)
Heat stable nuclease (+)
Gram (+)
Cocci
 facultative anaerobes
Of test (++)
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2
Q

Toxins of staph aureus -

A
Protein A.
complement  inhibitor protein
Staphylokinase
Capsule
Bound coagulase
(clumping factor)
Hemolysin
Panton Valentine Leucocidin
Enterotoxin
Exfoliative or epidermolytic toxin
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3
Q

Culture of staph aureus

A
Blood agar
Hot cold phenomenon (toxin induced @ 37°c but clear on cooling @2to 8°c)
Selective media
Ludlam media
Milk salt agar
Nutrient agar
With glycerol monoacetate(pigment (+) d/t Beta carotene /golden yellow)
Slope(oil paint colony)
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4
Q

Staph aureus resistance

A

Penicillinase
PBP Altered(MRSA)
Vancomycin

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5
Q

Strains of staph aureus

A

Phage 2 ET A (Chro, heat stable) ET B(plasmid,heat labile)
Phage 1 enterotoxin F(TSS 1)
Protein A (Cowan 1 strain)

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6
Q

Enzymes of staph aureus

A
Hyaluronidase 
 coagulase
Thermonuclease 
Lipase
Serine protease. 
Function:bacterial survival and spread
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7
Q

Methods of strain identification

Staph aureus

A
Pulse field gel electrophoresis(genotyping- best method) 
Phage typing(epi strain 80/81)
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8
Q

Genes of staph aureus

A

Penicillinase- Blaz gene
MRSA-mec a gene
VRSA-dose dependant

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9
Q

Phage typing staph

A

80/81
Nutrient agar with susceptible strain
Phage added
Lysis of bacteria

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10
Q

Culture for resistant strain staph

A

MRSA
Mannitol salt agar with cefoxitin disk(yellow)

HA Vs CA
D test- lawn culture of MRSA strain in erythromycin (inducer) and clindamycin

VRSA
mic testing

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11
Q

Hosp acquired and Comm acquired staph

A

HA
Resistant
Less virulent
D Test positive

CA
Less resistant
More virulent
D test negative

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12
Q

MSCRAMM

A
Microscopic surface component recognising adhesive matrix molecules
Function: adhesion
Gene:agr(accessory gene regulator)
Eg:clumping factor
       Lectins
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13
Q

SCC

A
Staph cassette chromosome 
Gene encoding for virulence
Ass with insertion sequence
HA. 1,2,3
CA 4,5,6
10,11 zoonotic staph(intermedia,hypoxia)
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14
Q

Regulation of virulent gene expression staph

A

AGR

Sar

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15
Q

Pathogenesis of staph aureus

A

Adhesion
Colonisation
Invasion & evasion
Infection(local,metastatic)

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16
Q

Panton Valentine leucocidin

A

Synergohymenotrophic property
F &S
Cytolysis (PMN,macrophage,monocytes)
Invasive pathoogenesis

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17
Q

VRSA mic testing

A

VRSA >16micro gm/ml
VISA 4-8 micro gm/ml
VAN Sensitive <2microgram/ml

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18
Q

Adhesion

A

MSCRAMM

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19
Q

Invasion

A

Enzymes
Toxins(PVL)
Cell wall components(NAG,alpha toxin)-inflammatory response

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20
Q

Evasion

A

Microcapsule
Protein A
Chips

Function: antiphagocytic

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21
Q

Micrococcus

A
Gram (+)
Catalase positive
Mannitol of test (-)
Tetrad
 aerobic
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22
Q

Streptococcus classification

A

Alpha (viridans)
Beta(lancefield group A to V except I&J)
Gamma(enterococcus)

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23
Q

Grouping of streptococci

A

Lancefield
A to J
Based on carbohydrates C

Griffith typing
Subgrouping of A
Based on m protein

Emm typing
Based on m gene
(genotype)

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24
Q

Streptococcus proteins

A

Structural proteins
Capsule(polysaccharide with hyaluronic acid)
Lipoteichoic acid
M protein

Toxins & enzymes
Hyaluronidase (antigenic)
Streptodornase (antigenic)
Streptokinase 
Erythrogenic toxin(super antigen)
Streptolysin O(antigenic)
Streptolysin S
Serine protease(inhibit IL - 8)
25
Q

Diseases of streptococci

A
Scarlet fever
Pharyngitis
Pasties lines
Sandpaper rash 
Strawberry tongue 
PSGN
RHD
Cellulitis(Peu de orange)
Erysipelas
Necrotising fasciitis
Guttate psoriasis
Impetigo contagiosa
26
Q

Impetigo contagiosa

A

Honeycomb rash

27
Q

Necrotising fasciitis

Flesh eating bacteria

A

M1 M3

28
Q

PSGN

A

M1-4 M12

M47 M49 M57 M59 M53-55 M61

29
Q

scarlet fever

A

M28

30
Q

RHD

A

M5 M6 M1 M19

31
Q

Culture of streptococcus

A

Pike(transfer media) (sodium azide,crystal violet ,blood agar)
Crystal violet, neomycin,blood agar
Polymyxin/colistin,fusidic acid, blood agar

32
Q

Investigation of streptococcus

A

Aso titre >200(RHD)

Antistreptodornase (PSGN)

33
Q

Strawberry tongue

A
Kawasaki disease
VIT B12 deficiency
Scarlet fever
Food and drug allergy
TSS
34
Q

Strep c

A

Upper respiratory tract infection
S.equisimilis
Diff from gpA strep:ferment ribose not trehalose
Use:streptokinase for thrombolytic therapy

35
Q

Gp B

A

Strep agalactiae
Source female genital tract
Cause early(<1week),late(2-12 weeks)
Virulence polysaccharide capsule(10 types)
Screening @35-37weeks by swab culture of vagina and anorectum

36
Q

Strep F

A

Alpha haemolytic
Minute strep
Use:heterophile antigen for atypical pneumonia (primary)
capnophilic

37
Q

Group D

A

S bovis
Species gallilyticus infantarius
Subspecies gallilyticus,pasteurian,infantarius,coli
Ass:colon Ca ,polyp,bowel lesions

38
Q

Alpha haemolytic

A
Viridans streptococcus 
Salivarius
Sanguis
Mutants
Mites
Normal flora of mouth 
Induce: endocarditis (transient) by eating,toothbrushing,flossing,minor trauma,adherence to biological surfaces

Strep pneumonia

39
Q

Enterococcus

A
Commensal flora of normal bowel(<1%)
Faecalis(M/C)
Faecium(Most resistant)
Growth in 40%bile,9.6pH,6.5%NaCl
Temp 46 to 60 deg el &10deg cel
Test PYR positive
Spectacle eye appearance
40
Q

Virulence factors of enterococcus

A
Proteins
Secreted
Hemolysin
Gelatinise
Serine protease
Cocolysin (inhibit endothelium)
Lipoteichoic acid(increase Tnf alpha)
Pheromones(conjugation without fimbriae)

Surface(structural)
Adhesin of both org recognise MSCRAMM
(To host collagen fibronectin fibrinogen)
Stress protein of E.feacalis(Gls 24) resistance to bile salts

41
Q

Diseases of enterococcus

A
UTI
Bacteremia
Endocarditis
Meningitis
Intraabd pelvic and soft tissue infections
42
Q

Resistance of enterococcus

A
Van A(transposon) Vancomycin and teicoplanin
Van B (transposon) vancomycin
Van C(chromosome) vancomycin and teicoplanin
43
Q

Mechanism of resistance to penicillins

Enterococcus

A

PBP5
Mutation in gene encoding it
Hyper production of it

44
Q

Vancomycin resistance mechanism

Enterococcus

A

Replacement of the last peptidoglycan residue from D ALA to D LACTATE(high resistance) or D SERINE( low resistance)

Production of enzymes to destroy D ALA so that binding sites for vancomycin is not available

45
Q

High level aminoglycoside resistance

Enterococcus

A
Gentamycin >500 micro gram/L
Streptomycin >2000micro gram/L
Linezolid. 
Mutation in 23rRNA genes
rRNA methylase
Daptomycin 
Change in membrane homeostasis
46
Q

Investigations of enterococcus

A

PYR TEST positive

Bile esculin hydrolysis test black colour

47
Q

Culture of enterococcus

A

Blood agar gamma hemolysin, pin point colonies

Telluride agar black colonies

48
Q

Motile cocci

A

E gallinarum
E casseliflavus
Van C Resistance

49
Q

Virulence factors of pneumococci

A

Structural
Polysaccharide capsule(98 serotypes)
Can diffuse into tissue
Special soluble substance

Toxins

Techoeic acid
Peptidoglycan
Stimulates inflammatory response
IL6 IL1 TNF alpha

Pneumococcal H inhibitor
Inhibition complement system

Choline binding protein(CBPA)
Pneumococcal surface protein(pspc)

Neuraminidase(Nan A)
Pneumococcal surface adhesion(psa A)

Autolysin
Release the toxins

50
Q

Pneumococcus

A
Gram positive 
Alpha haemolytic
Lanceolate/flame shaped
Capnophilic
Bile soluble
Optochin sensitive
51
Q

Confirmatory test for pneumococcus

A

Bile solubility test

52
Q

Diseases caused by pneumococci

A

VAP
Exception >5-6 days and mdr pseudomonas
meningitis in adults fulminant
Otitis media* <5 yrs

53
Q

Tests for pneumococci (includes culture)

A

Inulin fermentation positive

Culture
Blood agar
Initially heaped up followed by alpha hemolysis
Draughtsman colony
Carrom coin colony

Optochinnsensitive
Zone of inhibition of alpha hemolysis

Bile solubility test
Lysed by bile

54
Q

Capnophilic bacteria

A

Gram positive cocci
Strep f
Beta haemolytic

Step pneumoniae
Alpha haemolytic

55
Q

Vaccines

A

PPV
23 serotypes

High risk for vaccine to be avoided
Chronic lung kidney heart liver d/s
Immunocompromised ,DM
Cochlear implantation *
Splenectomy

PCV
Polyvalent conjugate vaccine
Serotypes 13 7 10/?13 serotypes

High risk
Ages<2m to 2 years
Premature infants

56
Q

PPSV/PPV

PCV

A

Polyvalent polysaccharide vaccine

Polyvalent conjugate vaccine

57
Q

Pneumococcal resistance

A

Alteration of PBP

58
Q

Pneumococcal treatment

A

Ceftriaxone
Vancomycin
Above drugs initially given

Followed by penicillins