Bacterial Disease Testing

Question 1

What are some reasons a culture is performed?

Answer 1

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

Question 2

What are some factors that may alter culture results?

Answer 2

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

Question 3

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

contaminant?

Answer 3

considered infection if >10^5

contaminant if

Question 4

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

Answer 4

usually issued within 24 hours

Question 5

Skin Flora
normal
pathogenic

Answer 5

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

pathogenic- strep pyogens, pseudomonas, proteus

Question 6

Mouth Flora

pathogenic

Answer 6

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

Question 7

Oropharynx Flora
Potential pathogens
Pathogens

Answer 7

PP- mycoplasma, bordatella pertussis, many others

pathogens- staph aureus, pseudomonas

Question 8

Conjunctiva Flora
normal
pathogens

Answer 8

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

pathogens- pneumococcus, pseudomanas (contacts!), strep

Question 9

GI tract Flora

pathogens

Answer 9

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

Question 10

Anterior Urethra Flora

Pathogens

Answer 10

chlamydia, gonorrhea, syphilis

Question 11

Vagina Flora
Normal
pathogens

Answer 11

normal flora varies with hormonal state

Pathogens- candida, trichomonas

Question 12

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

Answer 12

BEFORE!!!

*specimens should be transported as quickly as possible

Question 13

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

Answer 13

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

Question 14

Who selects the appropriate culture media?

What is the routine agar?

Answer 14

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

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

Question 15

Wound culture

Answer 15

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

Question 16

Abscess/boil/furuncle culture approach

Answer 16

• 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

Question 17

Eye- conjunctiva culture

Answer 17

• gently swab to collect drainage

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

Question 18

Throat culture

• generally obtained to rule out what?
• inform lab if what?

Answer 18

• 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

Question 19

Sputum culture

Indications

Answer 19

• 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

Question 20

What is a bronchoscopy?

Answer 20

sampling of the lower airway

-another potential diagnostic method

Question 21

Sputum culture stuff

Answer 21

• 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

Question 22

What will the sputum contain from an atypical pneumonias?

Answer 22

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

Question 23

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

Answer 23

Pink and purple

pink and purple

Question 24

Blood culture

indications

Answer 24

• 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

Question 25

What are blood cultures used to detect?

Answer 25

bacteremia (septicemia)

Question 26

What can a urine dipstick test?

Answer 26

``` 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

Question 27

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

Answer 27

``` Normals RBC: 0-5 HPF WBC: 0-5 HPF Bacteria: absent casts: 0-4 hyaline LPF crystals ```

Question 28

Lumbar puncture indications collection and transport

Answer 28

- 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

Question 29

Pleural fluid collection (thoracentesis) Therapeutic indication diagnostic indication

Answer 29

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

Question 30

Synovial Fulid evaluation | indications

Answer 30

swollen joint (is it infection? inflammation? what?) *medications should not be administered therapeutically at the same time

Question 31

Swab of the cervix would be to test what? | Female urethra?

Answer 31

cervix- gonorrhea, chlamydia, other organisms and PID | urethra- chlamydia

Question 32

What is a Wet Mount helpful in evaluating?

Answer 32

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

Question 33

Urethral culture - usually on male/female? - culture for what? - media?

Answer 33

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

Question 34

Stool culture | indications

Answer 34

- 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