Impact of BD Kiestra InoqulA streaking patterns on colony isolation and turnaround time of methicillin-resistant Staphylococcus aureus and carbapenem-resistant Enterobacterale surveillance samples.

OBJECTIVES: To determine if using alternative streaking patterns on the BD Kiestra InoqulA can impact colony isolation and improve turnaround time (TAT) of methicillin-resistant Staphylococcus aureus (MRSA) and carbapenem-resistant Enterobacterales (CRE) screening samples.

METHODS: A total of 1571 positive MRSA screening samples were studied, of which 755 screening plates were streaked by the standard pattern (4-Quadrant uniform S200) and 816 plates were streaked by an alternative pattern (Zigzag 3.5-1 S200). A total of 424 CRE-positive screening samples were studied, of which 211 screening plates were streaked by the standard pattern (Zigzag 2.5-1 inoc S200) and 213 plates were streaked by an alternative customized pattern (Zigzag 3.5-1 vertstreak s200).

RESULTS: There was a reduction in the number of MRSA screening plates with insufficient isolated colonies for confirmatory testing from 75 plates (9.9%) when using the standard pattern to 18 plates (2.2%) when using the alternative streaking pattern. MRSA cases with a TAT above 36 hours also reduced significantly from 144 (19.1%) to 20 (2.4%). The number of CRE screening plates with insufficient colonies for same-day confirmatory testing reduced from 16 (7.6%) when using the standard pattern to two plates (1.1%) when using the alternative customized pattern. CRE cases with a TAT above 36 hours also reduced from 16 (7.6%) to seven (3.3%).

CONCLUSIONS: The change in streaking patterns resulted in more plates with sufficient isolated colonies as well as reduced man-hours and materials required to perform subculture of mixed colonies and overall improvements in TAT.