MGIT 960 DST Inoculum Troubleshooting

Error Code

Description 

Possible Causes

Corrective action/s

X200

GU of the growth control tube was less than 400 at the end of the specified protocol time. 

Often a result of too little inoculum

•    Ensure that the DST was not set up on the same day the  primary MGIT tube signalled positive.

•   Ensure that the primary culture was diluted appropriately before inoculating ( 1:5 dilution if the DST was set up between three and five days after signalling positive and undiluted If the culture was worked up one or two days after signalling positive)

X400

GU of the growth control tube reached 400 before the specified protocol time. 

Often a result of an over-inoculated tube

•   Ensure that the primary culture was pure.

•     Ensure that the primary MGIT culture was not older than 5 days after signalling positive.

•     Ensure that a 1:5 dilution was made if the DST was set up between three and five days after signalling positive

•     Ensure that the Saline used for inoculum dilution was sterile. 

Question​

Answer 1​

Answer 2

Answer 3

Answer 4

Correct answer​

Correct explanation​

Page id​

Part of Pre-test​

Part of Post-test​

What is the reason for the X200 error in DST?

Over inoculum 

Under inoculum  

No inoculation 

Contamination 

2

X200 error is often a result of too little inoculum.

YES

YES

Over inoculum 

Under inoculum  

No inoculation 

Contamination 

1

YES

YES