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MICR-208 > Practical > Flashcards

Practical Flashcards

1
Q

What are the preferred urine sample types for testing?

A

1st morning, clean-catch, midstream

Acceptable methods include CC MSU, suprapubic aspiration, and in-and-out catheter.

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2
Q

What is the process for preparing a direct smear from swabs?

A

Roll all sides of swab on glass slide, dab tip to ensure sufficient contact.

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3
Q

What is the significance of the Q-score in sputum samples?

A

> 0: acceptable
≤0: unacceptable

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4
Q

What are the rejection criteria for urine samples?

A

Outside of transport time to lab, leaking specimen/other urine rejection criteria.

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5
Q

What are the limitations of direct smears?

A
  • Filter stains if ppt. present
  • Cannot distinguish cells/cellular elements if smear too thick
  • Smear may wash off if washed vigorously or not fixed
  • GP can look GN if left in alcohol/decolourizer too long
  • GP can look GN if iodine step is omitted
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6
Q

What are the QC organisms for direct smears?

A
  • S. aureus (pos - GPC)
  • E. coli (neg - GNB)
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7
Q

What is the reporting criteria for urine pathogens?

A

> 100X106 CFU/L: likely a pathogen
10 – 100X106 CFU/L: possibly a pathogen
<10X106 CFU/L: likely not a pathogen
≥3 organisms: likely contamination

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8
Q

What are the preferred sample types for blood cultures?

A

2 sets, collected from 2 different sites

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9
Q

What organisms are commonly identified in blood cultures?

A
  • Staphylococcus spp.
  • Streptococcus spp.
  • Enterococcus spp.
  • Enterobacterales
  • Candida albicans
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10
Q

What is the preferred sample type for vaginal smears?

A

Vaginal swabs between 15 – 64 y/o

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11
Q

What is the process for scoring bacterial vaginosis (BV)?

A

0 – 3: NF
3 – 6: indeterminate
7 – 10: BV

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12
Q

What is the primary reagent used in the oxidase test?

A

1% aqueous tetramethyl-p-phenylenediamine dihydrochloride

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13
Q

What does a positive catalase test indicate?

A

Bacteria can hydrolyze hydrogen peroxide (H2O2) into water & O2.

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14
Q

What are the special considerations for urine cultures?

A

Direct gram NOT done; if done, 10µL loop used.

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15
Q

What is the significance of the Nugent Criteria in vaginal smears?

A

Used for scoring bacterial vaginosis (BV).

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16
Q

What are common non-uropathogens found in urine samples?

A
  • Corynebacterium (other than C. urealyticum)
  • Coagulase-neg CoNS (other than S. saprophyticus)
  • Non-pathogenic Neisseria spp.
  • Viridans
  • Lactobacillus spp.
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17
Q

What are the transport time limits for urine samples?

A

Sterile container: 2h @ RT, 24h in fridge; Boric acid: 48h @ RT.

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18
Q

What are the characteristics of a moderate count of bacteria in direct smears?

A

6 – 30 bacteria observed.

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19
Q

What is the purpose of using a wooden stick or platinum for catalase testing?

A

To avoid false positive results caused by nichrome loops/wires.

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20
Q

What is the recommended incubation environment for blood culture plates?

A

AE, 48h @ 35-37°C for BA, MAC, CNA/PEA.

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21
Q

What is the significance of the phrase ‘indirect gram’ in blood culture reporting?

A

Indicates further report to follow.

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22
Q

What are common pathogens in sputum samples?

A
  • S. pneumoniae
  • S. aureus
  • M. catarrhalis
  • H. influenzae
  • Rhodococcus spp.
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23
Q

What is the importance of counting PMNs in sputum samples?

A

To assess the quality and potential infection in the sample.

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24
Q

What are the sample types for sputum collection?

A
  • Expectorated
  • Saline-induced
  • ETT
  • BAL
  • Bronchial brush
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25
What is the oxidase reaction for Actinomyces spp.?
Oxidase (+) ## Footnote Actinomyces species are typically oxidase positive.
26
What is the oxidase reaction for Enterobacterales?
Oxidase (-) ## Footnote Enterobacterales are a family of bacteria that are oxidase negative.
27
What does 'LF' mean on MAC agar for E. coli?
LF means lactose fermenter ## Footnote E. coli ferments lactose, producing acid and gas.
28
What mnemonic represents nonmotile Enterobacterales?
The SKY moves but these guys don’t ## Footnote Nonmotile organisms include Shigella spp., Klebsiella, and Yersinia.
29
What does aerogenic mean in relation to E. coli?
Let the gas ESCape ## Footnote E. coli and Salmonella spp. are known to produce gas during fermentation.
30
What does H2S producer mean in Enterobacterales?
SCP ## Footnote Salmonella spp., C. freundii, and Proteus spp. produce hydrogen sulfide.
31
Which organisms are indole positive?
P. vulgaris, E. coli, K. pneumoniae ## Footnote Indole production indicates the ability to break down tryptophan.
32
What does citrate negative indicate in Enterobacterales?
YESS we love the green planet ## Footnote Organisms like Y. enterocolitica, E. coli, Shigella spp., and Salmonella spp. are citrate negative.
33
What is the indicator used for citrate utilization testing?
Bromothymol blue ## Footnote Bromothymol blue changes color from green to blue in alkaline conditions.
34
What color indicates a positive urease test?
Pink ## Footnote Positive urease test indicates the breakdown of urea into ammonia.
35
What does the Thayer Martin agar grow?
N. meningitidis & N. gonorrhoeae ## Footnote This selective medium is used for isolating Neisseria species.
36
What does CNA agar differentiate?
Shows hemolysis, aids in differentiating GPB & GPC ## Footnote CNA agar is selective for gram-positive bacteria.
37
What does the D-test detect?
Inducible clindamycin resistance ## Footnote Used for Staphylococcus and Streptococcus species.
38
What is the resistance mechanism for MRSA?
Altered target (PBP2a) ## Footnote MRSA resistance is primarily due to the mecA gene.
39
What does a positive D-zone test indicate?
Inducible clindamycin resistance ## Footnote Indicates that clindamycin treatment may not be effective.
40
What class of beta-lactamase is intrinsic to Enterococci?
HLAR (high-level aminoglycoside resistance) ## Footnote Enterococci are resistant to many antibiotics, requiring specific treatment strategies.
41
What is the significance of the E-test?
Confirmatory for resistance testing ## Footnote The E-test is used to determine the minimum inhibitory concentration (MIC) of antibiotics.
42
What does ESBL stand for?
Extended-spectrum beta-lactamase ## Footnote ESBLs are enzymes that confer resistance to a variety of beta-lactam antibiotics.
43
Name one organism that produces class A ESBL.
E. coli ## Footnote Other examples include K. pneumoniae and P. mirabilis.
44
What indicates susceptibility to carbapenems in ESBL producers?
Treated with carbapenems ## Footnote Carbapenems are often the last resort for treating infections caused by ESBL producers.
45
What does SPICEHAM stand for?
Serratia, Providencia, Indole positive Proteus, Citrobacter, Enterobacter, Hafnia, Acinetobacter, M. morganii ## Footnote This group may develop resistance during therapy with certain antibiotics.
46
What is the resistance mechanism of VRE?
Plasmids or transposons ## Footnote VRE can acquire resistance through genetic elements that are highly communicable.
47
What are the indicators for class A ESBL testing?
Cefpodoxime, ceftazidime, cefotaxime, ceftriaxone, aztreonam ## Footnote Resistance to any of these indicates the presence of ESBL.
48
What does a positive ONPG test indicate?
Yellow color indicates β-D-galactosidase production ## Footnote This enzyme hydrolyzes ONPG to produce a yellow color.
49
What does the term 'non-fermenters' refer to?
Bacteria that do not ferment carbohydrates ## Footnote Examples include Acinetobacter baumannii and Pseudomonas aeruginosa.
50
What does the term 'tolerant' mean in relation to Enterococci?
Inhibited by acceptable levels of drug, but only killed when in excess or used in combination ## Footnote This indicates the need for higher doses or combination therapy for effective treatment.
51
What are Class C ESBLs/AmpC producers?
Serratia spp., Providencia spp., P. vulgaris (indole pos), Citrobacter spp., Enterobacter spp., Hafnia spp., Acinetobacter spp., M. morgannii ## Footnote These organisms are known for their resistance to beta-lactam antibiotics.
52
What is the mechanism of resistance for Class C ESBLs/AmpC?
Beta-lactamase; inducible in the presence of antibiotics and expressed at high levels. ## Footnote This resistance mechanism is chromosomal.
53
Which antibiotics are used to treat Class C ESBLs/AmpC infections?
Aminoglycosides, fluoroquinolones, & carbapenems (last resort). ## Footnote Carbapenems are often the last line of defense against these resistant organisms.
54
What are Carbapenemase-Producing Organisms (CPOs)?
Enterobacterales, P. aeruginosa/putida, A. baumannii complex. ## Footnote CPOs are particularly difficult to treat due to their extensive resistance.
55
What tests are used for detecting CPOs?
Automated AST, chromogenic agar, mCIM, PCR. ## Footnote Each test has its own strengths and weaknesses in identifying resistant organisms.
56
What is the significance of a rectal swab in CPO testing?
HAS to be rectal swab, with visual stool present. ## Footnote This ensures accurate sampling for detection of resistant bacteria.
57
What does a red/pink color indicate on chromogenic agar?
E. coli. ## Footnote Different colors indicate the presence of various organisms.
58
What does a blue color indicate on chromogenic agar?
Klebsiella, Enterobacter, & Citrobacter. ## Footnote Color coding helps in the identification of specific pathogens.
59
What does a colorless appearance on chromogenic agar indicate?
Other Gram-negative bacteria (e.g., P. aeruginosa). ## Footnote This is significant for understanding the range of organisms present.
60
What does teal color indicate on chromogenic agar?
Enterococcus spp. ## Footnote It helps in distinguishing Enterococcus from other pathogens.
61
What are the criteria for interpreting results from the mCIM test?
≥19mm: not a CPO; 16-18mm with pinpoint or 6-15mm: CPO. ## Footnote These measurements help determine the susceptibility to carbapenems.
62
What are ESKAPE pathogens?
Enterococcus faecium (VRE), Staphylococcus aureus (MRSA), Klebsiella pneumoniae (CRO), Acinetobacter baumannii (CRO), Pseudomonas aeruginosa (CRO), Enterobacter spp. (CRO). ## Footnote ESKAPE pathogens are known for their ability to evade antibiotics and are associated with healthcare-associated infections (HAIs).
63
What is the highest mortality risk ESKAPE pathogen?
Enterococcus faecium (VRE). ## Footnote This pathogen is increasingly multidrug-resistant (MDR) and poses significant treatment challenges.
64
What are the main classes of antibiotics that inhibit cell wall synthesis?
Beta-lactams, Glycopeptides. ## Footnote These classes are crucial in treating bacterial infections.
65
What are examples of natural penicillins?
Penicillin V, Penicillin G. ## Footnote Natural penicillins are effective against Gram-positive bacteria but are destroyed by penicillinases.
66
What is the purpose of penicillinase-resistant penicillins?
Used for penicillinase-producing Staphylococcus. ## Footnote Methicillin and Oxacillin are examples of this category.
67
What do aminopenicillins target?
Better for Enterococci, beta-lactamase negative H. pylori, some Enterobacterales. ## Footnote Examples include Ampicillin and Amoxicillin.
68
What is the role of inhibitor combinations in antibiotics?
Amoxi-clav, Pip-tazo. ## Footnote These combinations enhance the efficacy of penicillins against resistant organisms.
69
What is the function of glycopeptides in antibiotic therapy?
Last line against MRSA, C. diff, & Enterococci. ## Footnote Vancomycin is a key example of a glycopeptide antibiotic.
70
What are lipopeptides used for?
Daptomycin for Gram-positive; Colistin for Gram-negative. ## Footnote These antibiotics have specific targets based on their structure.
71
What is the action of quinolones/fluoroquinolones?
Inhibit nucleic acid synthesis. ## Footnote Ciprofloxacin is commonly used for urinary tract infections (UTIs).
72
What does anti-folates refer to in antibiotic therapy?
SXT. ## Footnote This class inhibits metabolic pathways essential for bacterial growth.

MICR-208 (1 decks)

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