Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

FRCpath microbiology part 2 > bacterial biochemical test and agars > Flashcards

bacterial biochemical test and agars Flashcards

1
Q

oxidase positive

A

Pseudomonas spp
Burkhulderia
Moraxella
Aeromonas spp.
Vibrio spp
Campylobacter
Helicobacter
Actinobacillus
Capnocytophaga
HACIK (H variable)
Pasteurella spp.
Bordetella pertussis .

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Oxidase Negative

A

Enterobacteriales
Staphylococci
Streptococci
Enterococci
Neisseria
Yersenia
Salmonella
Shigella
Stenotrophomonas
Acinetobacter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Catalase Negative

A

Streptococci
Enterococci
Lactobacillus
Clostridium
Staph anaerobicus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the strept milliri group?

A

Milliri group have very small colony but large zone of haemolysis:
CIA :Constalatius , Intermedius , Angenosus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Beta Haemolytic bacteria

A

SUAR- narrow
Corynebacteria
Listeria
Group A,B,C,G strepts
Enterococuui
Clostridium : perfrengens , tetani , Novyi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

grows in air, may require CO2, star shaped non-haemolytic colonies with rough surface, may produce pitting of agar
– Catalase positive, Oxidase positive and Urease negative

A

Aggregatibacter actinomycetemcomitans

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

HACIK Organism :
requires 5% to 10% CO2, small moist colonies with clear centres surrounded by flat growth, non-haemolytic
– Catalase negative, oxidase positive and urease negative

A

Eikenella corrodens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

HACIK Organism : CO2 not required, either spreading corroding colony or smooth convex colony, often produces mucoid colonies with a small zone of β-haemolysis – Catalase negative, oxidase positive and urease negative

A

Kingella Kingae species:

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

may require CO2 addition, smooth, convex and opaque colonies, slight a-haemolysis
– Catalase negative, oxidase positive and urease negative

A

Cardiobacterium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

grows in air + CO2, yellowish non-haemolytic colonies 1.5mm at 24hr – Catalase negative, oxidase negative and urease negative

A

Aggregatibacter aphrophilus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

-Gram-positive rod - long, branching and sometimes beaded. -Slow-growing
-dry chalky colonies which are cream, pale orange or pink.
-It is weakly AAF by Kinyoun’s stain
-Also positive by Gomori methenamine silver staining.
-Co-trimoxazole is the first line treatment

A

N. asteroides and N. brasiliensis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

T/F: Capnocytophaga Canimorus is Oxidase positive

A

T

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

T/F:
Stenotrophomonas is Oxidase Negative

A

T

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

T/F:
Candida albicans is urase negative and Cryptococcus neoformans rapid positive

A

T

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Gram-negative rod, non-lactose fermenter, DNAse positive; some strains produce a bright red pigment .
-intrinsic colistin resistance , and many are AMPc producers
-carbapenems, ciprofloxacin and aminoglycosides are likely treatment options

A

Serracia marcescens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

important examples of intrinsically colistin-resistant organisms?

A

Edwardsiella spp, Burkholderia cepacia, Proteus spp, Providencia spp, Serratia spp

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

-Gram-negative
-facultative anaerobe
-nonmotile
-pleomorphic
-bipolar staining “safety pin”
- catalase +
- oxidase +
- commonly cause animal bite infection

A

Pasturella spp

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Wat are the 3 fastidious Haemophilus spp that can cause Infective endocarditis ( included in HACEK Group)?

A

1- Haemophilus parainfuenzae
2- Haemophilus aphrophilus
3- Haemophilus paraphrophilus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the commonest cause of septic arthritis in infants ?

A

Haemophilus influenzae type b

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

SMAC agar ? is selective for which bacteria and how it appear on the agar?

A

Selective agar for E. coli O157:H7
Non sorbitol fermenters and appear colorless or pale colonies

while Non O157:H7 appear red or pink due to sorbitol fermentation and change PH indicator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Why gram positives cant grow on SMAC?

A

Due to presence of bile salts and crystal violet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Why lactose -fermenting gram negatives cannot grow on SMAC?

A

Because sorbitol is the only carbohydrate source in the media

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

General identification features of Streptococci??

A
  • GPC
  • Catalase neg
  • Tend to grow in chains or pairs which then dissociate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are the Optochin-Resistant Viridans streps
Groups??

A

Mitis, Mutans, Salivarus, Sanguinis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
alpha-haemolytic Streptococci that lack Lancefield carbohydrate antigen?
~ Optochin sensitive : 1-Strep pneumoniae ~Optochin negative: 2- viridans streptococci- S. mitis, S. mutans S salivarus S sanguinis 3-Anginosis group (CIA): (previously miliri) S constellatus S intermedius S anginosis
26
What are the Gamma (non) haemolytic streptococci?
Streptococcus gallolyticus (previous bovis group) (They are streptococcui Lancefield group D) 1- s gallolyticus Infantarius 2-S gallolyticus Pasteurianus
27
Clinical info whin call out about strep bovis group bactraemia? and what are recommended investigations??
* it can Colonise GIT in 7% * can cause; 1- Septicaemia (if colitis/adenoma/GB disease), 2- IE (check for CoCa) 3- joint 4- Descitis 5- meningitis Investigations: Echo CT abdo Colnooscopy look for ?RUQ
28
T/F: Tetracycline has a breakpoint for all streptococci?
F Tetracycline has no breakpoint for viridans group streptococci Only has B/P for pneumococci and beta haemolytic strepotococci
29
Flucloxacillin has higher MIC for which one of streptococci?
group B streptococci
30
How to perform Colistin MIC ?
-Colistin MIC should be performed with broth microdilution -Quality control must be performed with : 1) a susceptible QC strain (E. coli ATCC 25922 or P. aeruginos a ATCC 27853) 2) colistin resistant E. coli NCTC 13846 (mcr-1 positive).
31
How to test for Cephiderocol MIC as per EUCAST?
By broth microdilution MIC in iron-depleted Mueller-Hinton broth
32
When suspecting samlonella spp what are the 3 quick biochemical test that can be performed?
Suspected colonies can be tested for: - Urease -ve - oxidase -ve - indole -ve
33
What is the Vi antigen ?
It is an acidic polysaccharide layer outside the cell wall, also known as a surface antigen. # Produced by salmonella Typhi #When fully developed, the bacteria are agglutinable with Vi antiserum and not agglutinable with “O” antiserum
34
What is the gram stain characteristics of Salmonella spp?
1- Gram-negative rods 2- Non-spore-forming 3- Predominantly motile (except serovar Gallinarum)
35
What are the recommended culture media used for Salmonella??
Non-specific media: 1- Blood agar 2-Cystine-lactose-electrolyte deficient (CLED) Specific media : 1-Xylose-lysine-desoxycholate agar (XLD) 2- Desoxycholate citrate (DCA) agar 3- Brilliant Green agar (BGA) 4- Bismuth sulphite agar (BSA) 4- mannitol lysine crystal violet brilliant green agar (MLCB) 4- α-β chromogenic medium (ABC)
36
How salmonella appear on CLECD and XLD agar?
1- CLED - Salmonella produces non-lactose fermenting colonies(Blue -green). 2- XLD - red with a black centre ( Salmonella Paratyphi A and Salmonella Typhi may not produce a black centre)
37
All Salmonella spp are motile , except ..??
serovar S gallinarum
38
What are the biochemical test for Salmonella? Urease/oxidase/indole lactose fermentation
#Non-lactose fermenters on CLED #Urease -ve #oxidase -ve #indole -ve.
39
T/F All all Enterobacterales are Oxidase test negatives ?
F all Enterobacterales are Oxidase negative except for Plesiomonas
40
E coli biochemical tests : Catalase Oxidase Urase indole
Catalase +ve Oxidase -ve Urase -ve Indole +ve
41
Morganella morganii Biochemical tests? Oxidase , urase , indole
Gram negative Bacilli NLF Oxidase -ve urease +ve Indole +ve
42
Which bacteria can agglutinate with salmonella polyvalent antisera?
Morganella proteus Hafnia
43
What make MacConkey agar a selective media?
#Bile salts: 1-inhibit non-intestinal bacteria 2- prevents Proteus spp swarming #Crystal violet dye inhibits Gram positives
44
Examples of fungal selective media ?
Sabouraud and Dermesel media
45
What makes Dermesel agar a selective for dermatophytes?
Cycloheximide inhibitory to moulds and yeasts
46
What makes Sabouraud agar a selective fungal media?
Bacterial inhibition: 1-Low PH 2-Chloramphinicol 3-Gentamicin
47
What is ARIA selective media?
Anaerobe Recovery and Isolation Agar- Neo Selective for anaerobes -addition of neomycin inhibits coliforms (facultative anaerobes)
48
T/F Bacitracin chocolate agar is Selective for Haemophilus spp
Y
49
Examples of multiple organism targets selective agars ?
#MacConkey for intestinal bacteria #ARIA (Anaerobe Recovery and Isolation Agar) Neo Selective for anaerobes -addition of neomycin #Azt –blood agar with aztreonam- selective for Gram positives #Bacitracin chocolate agar. Selective for Haemophilus spp
50
Whats in B.cepacia selective agar?
Containes: 1- bile salts 2- Crystal violet 3-Ticarcillin 4-Polymixin B
51
Examples of Selective media –single organism target?
1-GC Chocolate agar for N.gonorrhoea 2-Hoyle’s agar for Corynebacterium diphtheriae 3-BCYE for Legionella 4- B.cepacia agar 5-CCDA agar for Campylobacter 6-Actinomyces selective agar 7- Aesculin agar - listeria 8-Pseudomonas CFC
52
What is the Campylobacter selective agar?
It is the CCDA media (Charcoal cefoperazone desoxycholate agar) A blood free medium with cefaperazone and amphotericin
53
What is the Actinomyces selective agar?
1- Nalidixic Acid to inhibit most aerobes, particularly gram-negative bacilli 2- Metronidazole to suppress other anaerobes
54
GC Chocolate agar
Selective for N.gonorrhoea Enriched with lysed blood. Added antibiotics: 1- vancomycin 2- colistin 3- trimethoprim 4- amphotericin
55
Pseudomonas CFC ??
It is the Cetrimide fucidin cephalosporin agar Selective for Pseudomonas spp Formulated to enhance pigment production. (Cetrimide selective for PsA)
56
What are the components of Listeria aesculin agar?
fosfomycin cefotetan colistin Aesculin
57
T/F Manitol salt agar is selective and indicator media for streptococci?
F Staphylococci
58
What is the color indicators in CLED agar?
Bromothymol blue pH indicator 1- LF : yellow 2-NLF: blue/green
59
What is the CLED agar?
Cysteine Lactose Electrolyte Deficient agar
60
What is teh color indicator in XLD agar?
Phenol red turn to yellow with low PH (due to Xylose fermintation) - Coliforms : yellow - shigella : red
61
What is the XLD agar?
- xylose lysine desoxycholate - Desoxycholate inhibits Gram positive organisms. - Coliforms ferment xylose to produce acid. - This turns the phenol red indicator yellow. - Shigella spp doesn’t ferment xylose, so colonies are red - Salmonella produce hydrogen sulphide : black-centred colonies.
62
What is the color indicator in MacConky agar?
Neutral red LF: Pink NLF: Yellow
63
What is DCA agar? and what is the color indicator?
Desoxycholate citrate agar For Salmonella and Shigella LF: pink NLF: colourless
64
What is teh diff b/w MacConkey and CT -SMAC?
Sorbitol rather than lactose in CT-SMAC
65
What is CT-SMAC?
Cefixime/Tellurite-Sorbitol MacConkey Sorbitol instead of lactose fermentation
66
What is the importance of CT-SMAC?
Non-sorbitol fermenters= clear colonies = E.coli O157
67
What is the colour indicator of TCBS agar?
PH indicators bromothymol blue and thymol blue -Yellow: Vibrio cholerae -Blue/green :V.parahaemolyticus
68
What is the TCBS agar?
-Thiosulphate Citrate Bile Salt Sucrose -A selective/indicator isolation medium for pathogenic Vibrio spp -High salt & alkaline media - Sucrose fermentatio=increased acidity - Yellow colonies: Vibrio cholerae - Blue/green :V.parahaemolyticus
69
T/F Oxoid Brilliance UTI agar containes 1 chromogen?
It contains 2 chromogens 1- One is cleaved by Beta-galactosidase produced by E.coli resulting= pink 2-The other cleaved by Beta glucosidase by Enterococci= blue Also contains tryptophan as an indicator of tryptophan deaminase by Proteus/ Morganella/ Providencia= brown colonies
70
71
Examples of chromogenic agars?
1- Oxoid brilliance UTI based on CLED 2- ChromID Group B –pink/red 3- Brilliance MRSA2 –contain cefoxitin= Blue colonies 4- Brilliance Candida agar: - C.albicans green - C.tropicalis blue - C.glabrata brown - C.krusei pink 5-ESBL, VRE, (CPE)
72
What are the color codes in Brilliance candida agar?
4- Brilliance Candida agar: - C.albicans green - C.tropicalis blue - C.glabrata brown - C.krusei pink
73
What are the agar media that used for susceptibility testing?
1-Mueller-Hinton agar for most Gram-negatives, staphylococci and enterococci 2- MHBlood (addition of blood) for: - Streptococci - H.influenzae - M.catarrhalis- - L.monocytogenes 3- FAA + blood for anaerobes
74
Examples of liquid media?
1-Robertsons cooked meat Enrichment broth for sterile sites/ tissues 2- Selenite broth: Salmonella 3- Alkaline peptone water:Vibrios 4- Modified Tryptone Soya Broth : E.coli O157 5- Kirchner medium TB culture medium for CSF, tissue 6- MacConkey broth: for coliforms
75
What are the types of TB Cultures?
1- Solid media. Lowenstein-Jensen slopes : - Egg-based medium - Pyruvate for M.bovis - Incubate at 28-30C for M.marinum 2- Kirchner’s liquid medium for CSF 3- Automated liquid culture system ie MGIT (Mycobacteria Growth Indicator Tube): faster time to detection
76
T/F: Moraxella catarrhalis usually showes Indoxyl acetate positive test?
T Indoxyl acetate positive
77
What are the organisms that give positivev Indoxyl acetate?
1- Campylobacter jejuni 2- C. coli 3- Moraxella cararrhalis
78
What is the reaction to Bacitracin for Strept A and H influenzae
Bacitracin 1- Group A strep sensitive 2-H.influenzae resistant
79
What are the Haemophilus spp X+V Factors requirement?
X+V factors: 1- H.influenzae needs both 2- H.parainfluenzae V onl 3-H.ducreyi X only
80
Aesculin Positive organisms?
1-Enterococcus 2-Streptococcus anginosus group 3- Streptococcus bovis group 4-Listeria
81
T/F Hockey puck sign can be seen with Moraxella catarrharis colonies?
T
82
Biochemical tests of Moraxella catarrhalis? Oxidase - catalase - glucose and lactose fermintation
Oxidase : Pos Catalase : Pos Glucose and lactose Nonferminters Tributyrin test +ve (diif from Nisseria)
83
Whta are the Virulance factors of Moraxella catarrhalis ?
1- Adhesin 2-Biofilm formation 3-Beta-lactamase production
84
A single test that can diff Moraxella from Nisseria spp?
Moraxella is Tributyrin test +ve
85
What biochemical test that can diff Moraxell acatarrhalis from Other Morraxella spp?
DNase test +ve (only M catarrhalis but not other Moraxella spp)
86
Moraxilla catarrhalis gram stain ?
- Gram negative coccobacilli - can resist decolorisation -can appear as diplococci (similar to Nisseria)
87
Moraxella Growth?
- Blood or chocolate agar - non-haemolytic - small, opaque, grey-white - smooth, flat, uniform, buff colonies(similar to Nisseria) - Can showe Hockey Puck sign - Catalase and oxidase positive. - Do not ferment glucose or lactose.
88
Commonest pasteurella spp?
P maltocida P canis.
89
Pasteurella microscopy?
-GNB -Bipolar staining - May be capsulated - non-motile
90
Pasteurell growth?
- Catalase and oxidase +ve (except P. bettyae) - Non-haemolytic grey Viscous colonieS - Strong mucinous odour resembling Haemophilus influenza - fails to grow on MacConkey agar/CLED
91
Microscopy of Kingella
-Fastidious GN coccobacilli -pairs/short chains -Bacilli or coccobacilli -Has tapered ends -Nonmotile -Capsulated but non-spore-forming
92
What are the commonest Kingella spp?
K. kingae K. denitrificans K. negevensis K. oralis
93
Culture growth of Kingella ?
-Capnophilic and facultatively anaerobic -Beta-haemolytic colonies on BA -Marked pitting of the agar surface.
94
Biochemical tests of Kingella ?
catalase, urease, and indole tests -ve Oxidase +ve
95
What are the possible Infections that can caused by Eikenella??
1-Head and neck infection, sinusitis, 2- Pulmonary septic emboli 3- IE 4- BJI (Needle licker osteomyelitis &Toothpick septic arthritis) 5-Intra-abdo :pancreatic/ liver abscess ("Fishbone abscess" ) 6-Chorioamnionitis 7-human bite wounds (“clenched-fist injuries”) 8-Skin infection in IVDUs
96
Biochemical tests of Eikenella?
Oxidase +v Catalase/urase/indole -ve
97
Microscopy of Eikenella spp?
-GN fastidious Cocco-bacilli -Facultative anaerobic -Non-motile -Encapsulated but non-spore-forming
98
Culture growth of Eikenella spp?
-Can grow aerobically or anaerobically -Requires hemin (X factor) -Capnophilc -Very low-growing -small, pin-point colony -Bleach-like smell -Pitting colonies -Yellow-grey with greenish discolouration on BA
99
Eikenella are usually non-susceptible to??
-Clindamycin - Macrolides - Aminoglycosides – gentamicin, amikacin etc - Metronidazole.
100
What are the commonest Aggregatibacter spp?
1- Aggregatibacter actinomycetemcomitans 2-Aggregatibacter aphrophilus - (formerly Haemophilus aphrophilus and Haemophilus paraphrophilus) 3- Aggregatibacter segnis 4- Aggregatibacter kilianii
101
Identification of Aggregatibacter species??
-GN Cocco-bacilli -Facultatively anaerobic -Can shows filamentous forms -Greyish-white colonies - Non-motile and non-haemolytic -Indole, urease -ve -Oxidase & catalase variable.
102
What are the commonest infections caused by Aggregatibacter spp?
1-periodontitis 2-Brain abscess 3-Actinomycosis 4- IE (part of HACEK)

FRCpath microbiology part 2 (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions