Carba-R assay

TEST DESCRIPTION

Detection of the five most common genes associated with carbapenem-nonsusceptibility by polymerase chain reaction (PCR). These genes are:

• IMP: Imipenemase 
• VIM: Verona integron-mediated metallo-beta-lactamase
• NDM: New Delhi metallo-beta-lactamase
• KPC: Klebsiella pneumonia carbapenemase
• OXA-48: Oxacillinase (class D)

When organisms no longer respond to carbapenems (a class of antibiotics), they are called CROs (carbapenem-resistant organisms). Knowing whether a patient has a CRO can inform treatment choice and improve infection prevention and control.

Methodology

PCR

Reference range

Not detected

TEST FREQUENCY & RESULT AVAILABILITY

Performed daily. Results are typically available within 1 business day after specimen receipt.

ACCEPTABLE SPECIMEN TYPES AND COLLECTION

• Rectal or perirectal swabs
• Bacterial isolates
• Detailed collection instructions appear below

SPECIMEN STORAGE

Rectal or perirectal swabs: Store in transport tube at room temperature (15–28°C/59–82°F) for up to 5 days.

Bacterial isolates: Store at ambient or refrigerated temperature (must be viable for subculture).

SPECIMEN TRANSPORT

Shipping conditions should follow the temperature and time requirements outlined above.

REJECTION CRITERIA

• Highly soiled swab specimens
• Swabs in transport tubes not stored at 15–28 °C or are received more than 5 days after collection
• Swabs in transport tubes other than the Copan dual swab transport in Stuart medium
• Bacterial isolates that do not have an intermediate or resistant profile to a carbapenem by antibiotic susceptibility testing (AST)
• Bacterial isolates without AST results
• Bacterial isolates other than Enterobacterales, Acinetobacter baumannii, or Pseudomonas aeruginosa
• Isolates that are not viable upon subculturing
• Mixed cultures are highly discouraged

CODES

CPT: 87150

LOINC: 85502-3

Test code: 2350

TEST FEE

Refer to the current fee schedule.

DETAILED SPECIMEN COLLECTION INSTRUCTIONS

1. Paired rectal swabs in Copan dual swab transport
   1. Carefully insert both swab tips approximately 1 cm beyond the anal sphincter and rotate gently.
   2. See figures below for examples of acceptable and unacceptable swab specimens.
2. Paired perirectal swabs in Copan dual swab transport
   1. Carefully insert both swab tips no more than 1 cm into the anal opening before the anal sphincter and rotate gently.
   2. See figures below for examples of acceptable and unacceptable swab specimens.

Figure. Examples of Acceptable Swab Specimens for Xpert Carba-R Testing.

Figure. Examples of Unacceptable Swab Specimens for Xpert Carba-R Testing.