BACTE Flashcards
1
Q
best time to collect any type of spx for bacteriology
A
Acute phase of illness (w/n 72 hrs)
2
Q
T/F
It is acceptable to collect spx once antibiotic therapy has started
A
F
no/less organism recovered
3
Q
technique STRICTLY observed during collection and processing
A
Aseptic technique
4
Q
allowable duration of the transportation of collected samples (*w/o delay)
A
30 mins – 2 hrs
5
Q
LEVEL OF PRIORITIZATION
A
- Critical / Invasive
- UNPRESERVED
- Quantitation required
- Preserved
- Batch processing
6
Q
example of critical spx or obtained thru invasive procedures
A
CSF
amniotic fluid
blood
pericardial fluid
heart valves
7
Q
example of unpreserved spx
A
feces
sputum
wound drainage
8
Q
example of spx with quanti required
A
catheter tip
urine
tissues for quantitation
9
Q
ex of preserved spx
A
urine, feces, swab in holding media
10
Q
ex of spx for batch processing
A
sputum
AFB culture
11
Q
performed using colony counting to r/o UTI; delay w/ quantitation may affect the count
A
Urine C/S
12
Q
PURPOSE OF BLOOD CULTURE
A
r/o:
Bacteremia
Septicemia/sepsis
13
Q
high no. of bacteria in the blood but NOT ENOUGH TO CAUSE HARM or S/S to px
A
Bacteremia
14
Q
high no. of bacteria in the blood, causing harm (S/S) to the px
A
Septicemia/sepsis
15
Q
no.1 cause of community-acquired UTI; GIT flora
A
E. coli
16
Q
Ex of Blood pathogens
A
E. coli
P. aeruginosa
S. aureus
17
Q
blood pathogen that is NEVER a normal floraa
A
P. aeruginosa
18
Q
most common cause of sepsis
A
S. aureus
19
Q
normal flora but affects anterior nares
A
S. aureus
20
Q
Process of cleansing the phleb site prior to collection to ensure that the blood submitted for culture is not contaminated
A
70-95% alcohol –>
Iodine scrub –>
Alcohol rinse
21
Q
Common contaminants in blood submitted for culture
A
Viridans streptococci (S. anginosus, S. salivarius, S. sanguinis, S. mitis, S. mutans)
Staphylococcus epidermidis
Propionibacterium acnes (recent: Cutibacterium acnes)
22
Q
Dilution of Blood to Media
A
1:10
23
Q
Duration of Routine blood culture
A
7 days
24
Q
Duration of Leptospirosis detection
A
8 weeks
25
Gold std for Leptospirosis detection?
Spx required?
MAT – Macro/micro agglutination test
SERUM – Ab detection
26
used in micro agglutination test
live leptospira
27
used in macro agglutination test
heat-killed leptospira
28
Duration of Brucellosis detection
3-4 weeks
29
Rapid test for Brucellosis detection
Optimal spx?
SAT (serum agglutination test)
Blood
30
T/F
All brucella spp. are animal normal flora but not of man.
T
In man: causes febrile disease (recurrent fever)
31
4 signif. brucella spp.
abortus
suis
canis
melitensis
32
T/F
brucella are culturable but culture is not usually done
T
most preferred test - SAT
33
no. of sets to be collected for blood culture
2-3 (usually 2 in practice)
34
best time to collect blood for blood culture
During peak of fever
35
blood amount to be collected for blood culture in the ff:
adult
pediatric
infants
Adult: >20 mL
Pediatric patients: 1-10 mL
Infants: 0.5-1 mL
36
How is 2 time collection done for blood culture?
both arms; 1 hr interval (2 sets: for aerobic & anaerobic culture)
37
1-time collection is only allowed in these cases. How many mL of blood must be collected for blood culture?
STAT cases
40 mL
38
routine anticoagulant for bacterial blood culture
0.025% SPS
39
disadvantage of 0.025% SPS
what is the remedy
inhibit: Neisseria, Gardnerella
+1% gelatin
40
anticoagulants used for molecular procedures only (PCR)
White top tube w/ EDTA
41
Media used for Blood culture
* Tryptic Soy Broth (TSB)
* Brain Heart Infusion (BHI) agar
* Brucella broth – esp. for brucellosis det.
* Castaneda bottle - brucella det. (biphasic)
42
spx collected to r/o bacteremia and septicemia
blood
43
spx collected to r/o bacterial meningitis
CSF
44
Process of CSF collection
Lumbar tap (invasive)
45
CSF tube no. used for micro
2
*if only 1 submitted, micro is the priority
46
Storage temp of CSF
37C
47
Transport temp of CSF
RT
48
CSF processing
Centrifuge CSF →
remove supernatant →
left are sediments (for smear preparation & culture use)
49
USUAL BACTERIAL ISOLATES IN CSF
Streptococcus agalactiae
Haemophilus influenzae serotype b
Streptococcus pneumoniae
Neisseria meningitidis
Listeria monocytogenes
50
agent of neonatal meningitis isolated in CSF
Streptococcus agalactiae
51
agent of children (<5 y/o) meningitis isolated in CSF
Haemophilus influenzae serotype b
52
agent of adult (>29 y/o) meningitis isolated in CSF
Streptococcus pneumoniae
53
agent of meningitis in 5-29 y/o isolated in CSF
Neisseria meningitidis
54
agent of meningitis in elderly/immunocompromised isolated in CSF
Listeria monocytogenes
55
To do after CSF collection from a shunt
Add thioglycolate
56
Very versatile media; allows growth of facultative anaerobes, strict aerobes, anaerobes
thioglycolate
57
spx to r/o repeated UTI
urine
58
usual request to r/o repeated UTI
Urine culture & sensitivity (C/S)
59
specimen of choice for bacterial culture to r/o repeated UTI
Clean catch midstream urine
60
spx for those unable to void urine
Catheterized urine
61
urine spx for anaerobic culture
Suprapubic urine
62
urine spx for molecular studies like PCR
First morning urine
63
CAUSATIVE AGENTS OF UTI
E. coli
S. saprophyticus
Klebsiella
Enterococcus faecalis
64
no. 1 cause of community-acquired UTI
gram negative rod; normal GIT flora
E. coli
65
#1 cause of UTI in young female and in elderly
women with catheter
S. saprophyticus
66
same family w/ E. coli; under Enterobacteriaceae that can also cause UTI
Klebsiella
67
gram + cocci that can cause UTI
Enterococcus faecalis
68
Determines the # of colonies / mL of urine by using a colony counter (ideal) or by manual counting
Colony count
69
loop required in colony count
calibrated loop (1 or 10 uL)
*determine DF
70
DF if loop size is 1 uL
1000
71
DF if loop size is 10 uL
100
72
formula for colony count
of colonies counted x dilution factor = colony count/ml of urine
73
colony count considered as UTI
>100,000
74
media used in colony count
MHA
*usual media for susceptibility testing
75
preferred urine preservative; maintains accurate colony count
Boric acid
76
spx to r/o LRTIs (pneumonia, bronchitis, TB)
sputum
77
Patient prep for sputum collection submitted for bacterial culture
Patient must be instructed to rinse/gargle with water prior to collection and cough deeply into container (5-10 mL sputum)
78
amt. of sputum required for bacterial culture
5-10 mL sputum
79
what must be done when spx submitted for sputum culture is NONSTERILE
evaluate quality → Bartlett’s Classification
80
checks if the spx is sputum or saliva? what is the criteria to be considered as SPUTUM (TRUE RESPIRATORY SAMPLE)?
Bartlett’s Classification
SPUTUM (true respiratory sample) - alveolar macrophage
SALIVA (not a respiratory sample) - >10 SECs, <25 PMNs
81
CAUSATIVE AGENTS OF PNEUMONIA
Pseudomonas aeruginosa
Klebsiella pneumoniae
Streptococcus pneumoniae
Haemophilus influenzae
82
cause pneumonia in those w/ cystic fibrosis
Pseudomonas aeruginosa
83
#1 cause of ventilator-associated pneumonia (intubated px)
Pseudomonas aeruginosa
84
TB agent; slow-growers (take weeks to produce growth)
Mycobacterium tuberculosis
85
M. tuberculosis is what type of BSL pathogen? culture of this organism must be done using BSC class?
BSL 3 pathogen
BSC Class 2
86
sputum for TB identification must undergo:
Decontamination – remove contaminants and normal flora
Digestion – liquefy the viscous sputum to free any trapped organisms
87
Gold standard for digestion & decontamination
N-acetyl-L-cysteine (NALC) + NaOH
NALC – mucolytic/digestant
NaOH – decontaminant
88
Frequently used agent; readily available; both a decontaminant and digestant
4% NaOH
89
T/F
4% NaOH only act as decontaminant when + w/ NALC
T
90
Added to sputum likely to contain P. aeruginosa
5% oxalic acid
91
T/F
All spx for TB det. requires decontamination & digestion
F
only non-sterile spx
92
types of sputum collection and no. to be considered (+)
1 spx collected in 3 days
(+): 2 out of 3
2 spx in 1 day
(+): 1 out of 2
93
Recommended sputum collection by DOH (to reduce TB cases)? Type of sputum spx needed in each collection?
2 specimens in 1 day
(+): 1/2
1st collection – first morning sputum
2nd collection – random sputum
94
Throat swab/Nasopharyngeal swab (NPS) is the spx for ID of?
Streptococcal infections (ex. pharyngitis) - S. pyogenes
Corynebacterium diphtheriae
Viridans strep
95
major throat pathogen
Streptococcus pyogenes
96
major throat flora
Viridans strep
97
major cause of subacute bacterial endocarditis (SBE)
Viridans strep
98
implicated in dental carries due to production of glucans and dextrans (enhances teeth attachment)
Viridans strep
99
spx collected to detect Bordetella pertussis
NPS
100
causes whooping cough
Bordetella pertussis
101
specimen processed to detect carrier state of N. meningitidis
NPS
102
spx required if N. meningitidis found in naso & oropharynx is normal flora (non-encapsulated)?
NPS
103
spx required if N. meningitidis is found to be pathogenic (encapsulated)?
CSF
104
Neisseria spp. is sensitive to 2Cs
cold temperature
cotton swab - contain fatty acids
Alternative: SWAB MADE FROM DACRON or CALCIUM ALGINATE
105
Swabs are only suitable for what type of bacteria
AEROBIC
106
Specimen to collect for culture when patient is on a ventilator/ intubated
Endotracheal aspirate
107
Not to be used for VIRUSES; inhibits replication
Calcium alginate
108
spx to r/o food poisoning, diarrhea, gastroenteritis
stool
109
GIT pathogens
Salmonella
Shigella
(never a normal flora of GIT)
110
invasive bacteria that causes bloody diarrhea
non-lactose fermenters & nonmotile (in general)
Shigella
111
4 Shigella serogroups
A – S. dysenteriae
B – S. flexneri
C – S. boydii
D – S. sonnei (LLF)
112
GIT pathogen with only 2 spp.? What are those?
Salmonella
S. enterica – human pathogen
S. bongori – animal pathogen
113
may be collected if stool collection is not possible
Rectal swab
114
Once stool is received, it is streaked immediately in?
EMB
MAC
SSA
115
manner of stool streaking for culture with 4 quadrants streaked on plated media
Semi-quantitation technique/isolation streak
116
what is isolated in stool streaked using semi-quanti technique?
area 4 - with isolated single colonies
117
automated program by ID of species through series of biochem tests and perform susceptibility testing
strictly requires PURE ISOLATES
VITEK system
118
Examples of Critical Values in Microbiology
* Positive blood culture
* Positive CSF gram stain or culture
* Positive cryptococcal antigen test or culture
* Positive blood smear for malaria
* S. pyogenes from a sterile site
* Positive acid-fast smears or positive Mycobacterium culture
* S. agalactiae or HSV from genital site of a pregnant woman at term
* Detection of significant pathogen (ie. B. pertussis, Brucella, Legionella)
119
What to do when critical values/ panic values are noted in micro:
REPORT THE RESULT ASAP
120
Types of bacteria processed in the lab:
Facultative anaerobes
Aerobes
Strict aerobes
121
bacteria that must not be exposed to air during incubation? what is required to prevent air exposure?
Facultative anaerobes
Gaspak Jar
122
bacteria requiring 21% O2 + 0.03% CO2 (placed at 37ºC, 18-24 hrs)
Aerobes
123
other aerobes requiring ↑ CO2
CAPNOPHILIC
(must be ensured that they are supplied with inc. CO2 by using a candle jar)
124
gaspak jar component that maintain anaerobiasis
Palladium pellets /catalyst
125
function of indicators in gaspak jar? give an example and its corresponding negative and positive color
ensure no presence of air
In O2 presence:
Methylene blue (BLUE)
Resazurin (PINK)
In O2 absence:
Colorless
126
Common failure of GasPak
inactivation of catalyst due to repeated use
127
CO2 needed by capnophilic bacteria? give an example of this bacteria
5-10% CO2
Neisseria
128
bacteria that is both Microaerophilic (5% O2) & Capnophilic
genus Campylobacter
129
Darting motility
Cause gastroenteritis
Stool pathogens
Microscopic appearance: wings of seagulls
genus Campylobacter
130
Anaerobic culture (gaspak jar) contents
5% CO2
10% H2
85% N2
131
Microaerophilic culture (candle jar) contents
5% O2
10% CO2
85% N2
132
2 general AST methods
Dilution method (quantitative)
Disk diffusion method – Kirby Bauer (qualitative)
133
Lowest concentration of the antibiotic that inhibited bacterial growth
Minimum Inhibitory
Conc. (MIC)
134
Lowest concentration of antibiotic that can kill bacteria
Minimum bactericidal conc./ Minimum lethal conc. (MBC/MLC)
135
Required depth of MHA for Kirby Bauer
3-5 mm
136
swab used and manner of streaking in MHA during Kirby Bauer tech
sterile cotton swab
overlap streaking
137
Size of antibiotic disk used in Kirby Bauer Technique
6mm
138
distance of the disks from the center used in Kirby Bauer Technique
24 mm
139
distance between 2 disks used in Kirby Bauer Technique
15 mm
140
RULE of stacking of plates in incubator for AST (kirby bauer)
not be >5 plates in 1 column
141
Incubation temp and duration of plates for Kirby Bauer
37°C for 16-18 hours
142
result in ZOI when:
* too thin agar
* very dry agar surface
* too light inoculum
Larger ZOI
False sensitive
143
result in ZOI when:
* too thick agar
* too much moisture on agar surface
* too heavy inoculum and too long incubation time
Smaller ZOI
False resistant
144
allowable no. of antibiotic disks on a 150 mm plate
No >12 disk
145
allowable no. of disks on a 100 mm plate
No >5 disk
146
Storage temp for antibiotic disks-working supply
2-8°C
147
Cell wall inhibitors
Beta lactams: Penicillin, Cephalosporins, Carbapenems
Glycopeptide: Vancomycin
148
Protein synthesis
inhibitors
Aminoglycosides: Gentamycin
Tetracycline
MLS (macrolide-lincosamide-streptogramin) – Erythromycin, Clarithromycin
149
AST of Streptococci is done using what media
Use MHA + blood (required since strep is fastidious)
150
Detects inducible clindamycin resistance among strains of S. aureus
D-test (double disk diffusion test)
151
Required when initial result of Erythromycin to Clindamycin is DISCREPANT
D-test (double disk diffusion test)
152
D-test (double disk diffusion test) is used to confirm the true result of what antibiotic
CLINDAMYCIN
153
used in D-test
15 ug Erythromycin
2 ug Clindamycin
*15 mm apart
154
gene that activates clindamycin resistance
erm gene
155
POSITIVE result of D-test? What does it indicate?
blunting/flattening of Clindamycin zone to produce D pattern
(+): Clindamycin RESISTANT
156
Uses a strip with single antibiotic of different conc. along its length
E-test/MIC on a stick
157
E-test/MIC on a stick is quali or quanti?
Quantitative AST → Dilution method
158
E-test/MIC on a stick is recommended for what type of bacteria
fastidious & aerobes
159
what is measured in E-test?
tapering = MIC
160
T/F
E-test/MIC on a stick is routinely used in the lab
F
Not routinely used; used in research
161
(+) result of E-test
Ellipse of growth inhibition
162
aka Serum Bactericidal Test
Schlichter test
163
Measures activity of antibiotics in patient’s own serum against the pathogen, to detect if patient is receiving effective tx for infection
Serum Bactericidal Test/Schlichter test
164
Screening test for carbapenemase-producing organisms
Modified Hodge Test
165
+ result of Modified Hodge Test
clover leaf like pattern of ZOI
