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

Abstract

ObjectivesTo 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. MethodsA 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). ResultsThere 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%). ConclusionsThe 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.