Microbiology Test

Test : Intravascular Device Culture


Indications : The test is carried out for patients who have clinical symptoms of bacteremia. The samples for the test include peripheral blood, blood collected through the catheter and also the tip of the catheter used to support the patient in the ICU.

Both the blood samples were inoculated separately into lysis-centrifugation tubes and centrifuged. A sample of the sediment was transferred onto different petri plates containing agar and were allowed to grow in culture.

For the last sample, the catheter tip was cut off. It was then placed on a petri plate containing chocolate blood agar and rolled three to four times using a sterile forceps. The culture was allowed to grow.

Physiology : Intravascular -device- related bacteremia is (IDRB) a common infection affecting those in the hospital ICUs.

Intravascular devices are used for a variety of therapeutic and diagnostic purposes. It is mostly used in seriously ill individuals to provide continuous vascular access. These devices penetrate the integument and thereby, increase the risk of infection in these patients. Clinical symptoms of bacteremia include fever and increased blood pressure. Sometimes it could lead to a life-threatening situation.

Normal Range : Roll plate cultures: < 15 colonies, sonicated specimen < 10 4 colonies.

Interpretation : Normal : <15 colonies

The patient is reported to have IDRB if there is a presence of >15 CFU (of the same bacteria or fungi from PB sample ) grown from the cannula tip.

The amount of micro organism (bacteria and fungi) in the peripheral blood cultures is expressed as the mean value of both the peripheral blood cultures. It has been found that in most patients, the common causes for bacteremia are Pseudomonas aerugenosa and Staphylococcus sp. of bacteria.

Sample : I.V. catheter tip, foreign body, blood collected through catheter.

Test Method : Roll plate semiquantitative cultures, Quantitative sonication method, Comparative quanitiaive cultures.

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