Bacterial Disease Testing Flashcards

1
Q

What are some reasons a culture is performed?

A
  • confirm a dx
  • exclude a dx
  • screening
  • monitor course of disease
  • monitor response of therapy
  • stage the severity of the disease
  • provide a prognosis
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2
Q

What are some factors that may alter culture results?

A

improper technique/collection method, transport, or patient factors (medications)

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3
Q

What is the cutoff of growth to consider it an infection?

contaminant?

A

considered infection if >10^5

contaminant if

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4
Q

What would you expect to receive a preliminary report for most cultures?

A

usually issued within 24 hours

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5
Q

Skin Flora
normal
pathogenic

A

normal- staph epidermidis, *S. aureus, micrococcus, few gram neg bacilli moist skin, corynebacterium, propionibacterium

pathogenic- strep pyogens, pseudomonas, proteus

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6
Q

Mouth Flora

pathogenic

A

strep pneumoniae, strep pyogenes, neisseria meningitidis, haemophilus influenza, neisseria gonorrheae

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7
Q

Oropharynx Flora
Potential pathogens
Pathogens

A

PP- mycoplasma, bordatella pertussis, many others

pathogens- staph aureus, pseudomonas

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8
Q

Conjunctiva Flora
normal
pathogens

A

normal- cornyebacterium, neisseria, moraxellae, staph and strep, occasional haemophilus and parainfluenza

pathogens- pneumococcus, pseudomanas (contacts!), strep

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9
Q

GI tract Flora

pathogens

A

C. diff, salmonella, toxic strains E. coli, helicobacter pylori (in duodenum)

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10
Q

Anterior Urethra Flora

Pathogens

A

chlamydia, gonorrhea, syphilis

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11
Q

Vagina Flora
Normal
pathogens

A

normal flora varies with hormonal state

Pathogens- candida, trichomonas

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12
Q

Do you obtain a specimen before or after administration of antibiotics/?

A

BEFORE!!!

*specimens should be transported as quickly as possible

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13
Q

How long do blood cultures take?
How long do most routine cultures take?
how about anaerobes?

A

blood cultures take 48-96 hours
routine cultures (urine, throat, sputum) take 24-48 hours
Anaerobes- 48-72 hours

*almost always get gram stain with culture in most settings

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14
Q

Who selects the appropriate culture media?

What is the routine agar?

A

The LAB! (so why is this a slide??)

routine- blood agar
thioglycollate media- a liquid media used to supplement plated media

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15
Q

Wound culture

A

Usually pus present, try to get the good stuff from the middle

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16
Q

Abscess/boil/furuncle culture approach

A
  • incised and any fluid or material swabbed out with culture swab and sent to lab
  • important to get pus/exudate from deep in the wound to avoid surface contamination
17
Q

Eye- conjunctiva culture

A
  • gently swab to collect drainage

- place in appropriate container and send to lab at 25 degrees C

18
Q

Throat culture

  • generally obtained to rule out what?
  • inform lab if what?
A
  • rule out strep pharyngitis
  • inform lab if you’re trying to ID something else such as N.gonorrheae because it requires special medium
  • avoid touching any other part of the mouth
  • often indicated if the in office rapid strep is negative
19
Q

Sputum culture

Indications

A
  • hospital acquired pneumonia
  • hospitalized patients with pneumonia (CAP) and any of the following criteria: ICU admission, failure of outpateint abx therapy, cavitary lesion, active alcohol use, pleural effusion

NOT indicated in:

  • most outpatient CAPs
  • Management of bronchitis
  • initial management of acute exacerbations of COPD
20
Q

What is a bronchoscopy?

A

sampling of the lower airway

-another potential diagnostic method

21
Q

Sputum culture stuff

A
  • may be inaccurate due to mouth flora (rinse out mouth, not eating 1-2 hours before collection)
  • suspect a pathogen if WBCs are present along with an overabundance of one type of organism
  • first morning sputum will represent a deeper pulmonary secretion
  • induce cough with nebulizer, pulmonary PT, aspiration, bronchoscopy
  • always get gram stain with culture
22
Q

What will the sputum contain from an atypical pneumonias?

A

abundant polymorphonuclear cells and few or no organisms will be seen on the gram stain

23
Q

What colors would appear on a sputum gram stain of strep pneumoniae?

A

Pink and purple

pink and purple

24
Q

Blood culture

indications

A
  • bacteremia
  • septicemia
  • unexplained post op shock
  • unexpected fever of several days duration
  • pneumonia
  • chills and fever in patients with: infected burns or UTIs, rapidly progressing tissue infections, postop wound sepsis, indwelling venous/arterial cath
  • debilitated patients receiving: antibiotics, corticosteroids, immunosuppressives, parenteral hyperalimentation
25
Q

What are blood cultures used to detect?

A

bacteremia (septicemia)

26
Q

What can a urine dipstick test?

A
pH
specific gravity
bilirubin
protein
glucose
ketones
blood
nitrite (indicates the presence of enerobacteriaceae that converts nitrate to nitrite)
leukocyte esterase (if positive, likely indicates pyuria)

*if negative but positive for sx of UTI, still want urine culture

27
Q

What would you expect to find in a microscopic analysis of urine sediment from spun urine?

A
Normals
RBC: 0-5 HPF
WBC: 0-5 HPF
Bacteria: absent
casts: 0-4 hyaline LPF
crystals
28
Q

Lumbar puncture
indications
collection and transport

A
  • to look for blood (possible subarachnoid hemorrhage)
  • to find the organism causing the meningitis or brain abscess

collect 1-5 ml of CSF, transport at 25 degrees C
4 tubes: 1. cell count, 2. glucose and protein, 3. gram stain and culture, 4. cell cound to compare to tube 1

29
Q

Pleural fluid collection (thoracentesis)
Therapeutic indication
diagnostic indication

A

therapeutic- relieves dyspnea

diagnostic- to test the fuild for TB, fungus, CEA level (tumor marker), cytology, culture, gram stain, pH

*go over the top of the rib because vessels and nerves go under the ribs

30
Q

Synovial Fulid evaluation

indications

A

swollen joint (is it infection? inflammation? what?)

*medications should not be administered therapeutically at the same time

31
Q

Swab of the cervix would be to test what?

Female urethra?

A

cervix- gonorrhea, chlamydia, other organisms and PID

urethra- chlamydia

32
Q

What is a Wet Mount helpful in evaluating?

A

vaginitis/ bacterial vaginosis
trichomonads
can reveal multiple PMNs
KOH (potassium hydroxide) wet mount can reveal candida organisms

33
Q

Urethral culture

  • usually on male/female?
  • culture for what?
  • media?
A
  • usually on male/female? Males
  • culture for what? GC (gonorrhea), chlamydia
  • media? thayer martin/ new york media
34
Q

Stool culture

indications

A
  • routine culture for those with prolonged diarrhea or haven’t been on abx or hospitalized
  • test of choice to check for the C. diff toxin