Blood Cultures - Exam 9

Question 1

Define bacteremia

Answer 1

The presence of bacteria in the blood.

Question 2

Define fungemia

Answer 2

The presence of fungi in the blood.

Question 3

Define septicemia

Answer 3

Bacteria is present in the blood, causing infection and reproducing within the bloodstream.

Question 4

What are the three types of bacteremia?

Answer 4

Transient, intermittent and continuous

Question 5

What type of bacteremia is described?

Organisms comprising of normal flora are introduced into the blood.

Answer 5

Transient bacteremia

Question 6

What type of bacteremia is described?
Organisms are released into the blood at a fairly constant rate and are continuously present in the blood with or without symptoms.

Answer 6

Continuous bacteremia

Question 7

What type of bacteremia is described?

Bacteria from an un-drained infected site are released into the blood spasmodically.

Answer 7

Intermittent bacteremia

Question 8

When does septicemia occur?

Answer 8

When bacteria and their toxins multiply - often at rates that exceed removal by phagocytosis.

Question 9

The following are symptoms of what?

Fever, chills, malaise, tachycardia, hyperventilation, and toxicity

Answer 9

Septicemia

Question 10

What are the four major groups of microbes found circulating in blood during disease?

Answer 10

Bacteria, fungi, parasites, and viruses

Question 11

What are the two types of fungus most often seen circulating in the blood during disease?

Answer 11

C. albicans (account for 8-10% of all nosocomial bloodstream infections.

Malassezia furfur (seen in patients receiving lipid supplements/ most often neonates)

Question 12

What are the three viruses most often seen circulating in the blood during disease?

Answer 12

Epstein Barr (invades lymphs), 
CMV (invades lymphs, monocytes, and PMNs), and HIV (invades certain T-lymphs)

Question 13

What are the four most common parasites found circulating in the blood during disease?

Answer 13

Plasmodium, Trypanosoma, Babesia, and Microfilariae (Loa Loa, Brugia, and Wuchereria)

Question 14

When is the ideal time to collect a blood culture?

Answer 14

30-45 min before a temperature spike

Question 15

What is acute febrile illness?

Answer 15

Rapid onset fever along with symptoms, can be caused by a wide range of pathogens

Question 16

What is empiric antibiotic therapy?

Answer 16

Antibiotic therapy given within the first 24 hours of admission

Question 17

When might empiric antibiotic therapy be indicated?

Answer 17

When a patient has an acute febrile illness

Question 18

What are two of the main diseases that may cause acute febrile illness?

Answer 18

Meningitis and bacterial pneumonia

Question 19

What are two instances where emergency surgery may be necessary for a patient suffering from acute febrile illness?

Answer 19

If the patient has suppurative arthritis or osteomyelitis

Question 20

Why do you need extra sets of blood culture bottles when treating a patient with fever of unknown origin?

Answer 20

To ensure that you are detecting the infectious agent and not a contaminant from equipment or natural body flora

Question 21

In the case of a fever with an unknown origin, how many blood cultures should be drawn initially and what is the interval between sets?

Answer 21

2 blood cultures should be drawn initially with an interval of 45-60 minutes, 2 additional sets can be then drawn 24-48 hours later

Question 22

What are interval draws used for?

Answer 22

To aid in determining if a continuous or intermittent seeding of the blood exists

Question 23

In the case of infective endocarditis, how many blood cultures should be drawn initially and in what time frame?

Answer 23

3 blood cultures in the first 1-2 hours of evaluation (3 separate venipunctures - should be done before therapy begins)

Question 24

In the case of infective bacterial endocarditis, how many blood cultures should be drawn and in what time frame? What do you do if those are negative?

Answer 24

3 blood cultures within the first 24 hours, with 30 minutes between each

Obtain 2 more sets on subsequent days

Question 25

What are the 5 groups of bacteria that may be a common cause infective endocarditis?

Answer 25

- Viridans Strep (normal oral flora - gains entry through gingivitis, periodontitis and dental manipulation) - Nutritionally Variant Strep - HACEK group - Enterococcus - S. aureus (most common cause of infective endocarditis)

Question 26

Who is at a higher risk of having infective endocarditis from the Viridans Strep group?

Answer 26

IV drug users because of the use of spit to "clean" the injection site

Question 27

What are the 4 groups of bacteria commonly associated with IV catheter bacteremia?

Answer 27

- S. epidermidis (produces biofilm made of complex sugars that adhere to catheter surface) - Other Coag Neg Staph - S. aureus - Enterobacteriaceae

Question 28

Bacteremia from extravascular sites of infection can come from...

Answer 28

Wounds, soft tissue, respiratory, CSF, and GU tract

Question 29

Which organisms are the common cause of bacteremia from a wound infection?

Answer 29

Anaerobes, P. aeruginosa, and Group A Strep

Question 30

Which organisms are the common cause of bacteremia from a soft tissue infection?

Answer 30

Anaerobes, Coag Negative Staph, P. aeruginosa, Group A Strep, and S. aureus

Question 31

Which organisms are the common cause of bacteremia from a respiratory infection?

Answer 31

H. flu and S. pneumoniae

Question 32

Which organisms are the common cause of bacteremia from a CSF infection?

Answer 32

H. flu, Listeria, N. meningitidis, S. pneumoniae, and S. aureus

Question 33

Which organisms are the common cause of bacteremia from a GU tract infection?

Answer 33

Enterobacteriaceae, and C. albicans

Question 34

What is the hospital standard for contamination rates?

Answer 34

3%

Question 35

How do you sterilize a venipuncture site for blood culture collection?

Answer 35

Cleanse with Chloroprep in a concentric fashion for 30 seconds and do not touch the skin after (even with gloves )

Question 36

What is the recommended volume for an adult blood culture bottle?

Answer 36

8-10 mL per bottle (percentage yield of positive culture drops if less than 10 mL per bottle is obtained)

Question 37

What is the recommended volume for each blood culture bottle for child?

Answer 37

1-5 mL proves to be satisfactory

Question 38

Which bottle should be drawn first if there is a difficult person to draw?

Answer 38

The aerobic bottle

Question 39

What is the ratio for ideal recovery?

Answer 39

1:10

Question 40

What does Trypticase soy broth/Brain heart infusion broth contain? What type of bacteria is this media good for?

Answer 40

Soybean and casein digests - good for aerobic bacteria

Question 41

What kind of organisms is Thioglycolate broth most ideal for?

Answer 41

Anaerobic bacteria

Question 42

What is Sodium Polyanetholsulfonate (SPS) media good for?

Answer 42

Preventing coagulation without harming the bacteria, inactivating neutrophils and certain antibiotics, and inhibiting the growth of certain bacteria.

Question 43

What types of bacteria does SPS inhibit?

Answer 43

P. aeruginosa, GC, N. meningitidis, and G. vaginalis

Question 44

What organism is Castaneda double medium good for recovering?

Answer 44

Brucella

Question 45

What is the biphasic technique, what are the conditions for incubation?

Answer 45

When the blood culture bottle contains both solid and liquid media. Needs to be incubated in 5-10% CO2 @ 35-37C for 30 days and tipped every 48 hours to inoculate agar surface, also needs to be subcultured at least twice a week.

Question 46

What is Fletchers medium and what organisms is it good for recovering?

Answer 46

Semi-solid media with rabbit serum and SPS. It is good for recovering Leptospira.

Question 47

What are the incubation conditions for Fletchers medium, how and when is it examined?

Answer 47

Incubated in the dark @30C for 28 days. Examined weekly by darkfield microscopy

Question 48

What are the incubation conditions for blood culture bottles?

Answer 48

Incubated @35C and held for 5 days

Question 49

What should be done immediately if a blood culture bottle is suspected to be positive?

Answer 49

A Gram stain and a follow up with the provider if the Gram stain is positive

Question 50

What are the three ways blood culture bottles are examined?

Answer 50

Macroscopically, radiometrically, and fluorometrically

Question 51

What are the three blood culture systems we should be familiar with?

Answer 51

BACTEC FX, ISOLATOR, and SEPTI-CHEK

Question 52

What are the common macroscopic observations of Gram Negative Bacilli in blood culture bottles (usually Enterics)?

Answer 52

Medium above red cell layer becomes turbid and gas bubbles are present

Question 53

What are the common macroscopic observations of Pneumococcus and Meningococcus in blood culture bottles?

Answer 53

Turbidity and a greenish tint to the medium

Question 54

What are the common macroscopic observations of Streptococcus in thioglycolate media?

Answer 54

Strep appears as cotton ball colonies on top of the sedimented red cells

Question 55

What are the common macroscopic observations of Staphylococcus in blood culture?

Answer 55

Staph frequently produces a large jelly-like coagulum and appears turbid

Question 56

What are the common macroscopic observations of Bacillus in blood culture?

Answer 56

Lysed RBCs and a thick film on the surface

Question 57

What are the common macroscopic observations of Clostridium in blood culture?

Answer 57

Produces a large head of has and lysed RBCs

Question 58

What are the common macroscopic observations of Bacteroides in blood culture?

Answer 58

Less gas than Clostridium and a foul odor

Question 59

What are the common macroscopic observations of H. flu in blood culture?

Answer 59

Little or no change in the media