Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1316 page)

   Broth media can be inoculated with a larger volume of specimen than agar plates, which may improve detection of infections with low concentrations of pathogens, but the amount of bacteria in the specimen cannot be estimated from broth cultures.

   Broth media may allow detection of some relatively aerotolerant anaerobic pathogens. Broth cultures have been associated with an increased rate of contamination.

   
Expected results:
No pathogen isolated

   
Turnaround time:
48–72 hours

   In positive cultures, additional time is required for isolation, identification, susceptibility testing, and further characterization, as appropriate.

   Special Collection and Transport Instructions

   Standard precautions apply. Ensure that material from the site of infection is collected.

   Decontaminate skin or mucous membranes that must be crossed to obtain the specimen.

   Use appropriate sterile supplies to collect the specimen. Place the specimen in a sterile, leak-proof container for transport. Ensure that the lid is firmly tightened, but avoid overtightening. Use specific transport medium and/or procedures as required for suspected pathogens (described below) or if transport to the lab will be prolonged (>2 hours). Apply a label to the specimen with information to identify the patient and type of specimen, as described below. Transport the specimen to the lab as quickly as possible, avoiding extremes of temperature. Note that collection protocols for some types of specimens require specific training and/or certification of the health care professional performing the collection. Examples include collection of bone marrow and CSF specimens.

   Limitations

   Anaerobic culture is recommended for infections at sites likely to be infected by anaerobic pathogens. Examples include pelvic infections, intra-abdominal infections, abscesses, and traumatic and surgical wounds. Certain aerobic pathogens, such as
Legionella
species, require special processing or culture techniques for detection.

   
Common pitfalls: