Assessment of improved sensitivity in Q-Line Kyokuto^® PBP2’ using our hospital’s blood culture positive bottles pretreatment method

Abstract

This study evaluates the sensitivity enhancement of Q-line Kyokuto^® PBP2’ using our proprietary pre-treatment method on blood culture-positive bottles. A total of 150 samples with positive blood cultures and direct identification of Staphylococcus spp. by VITEK MS were examined. Q-line Kyokuto^® PBP2’ was performed according to the package insert using the standard method with colonies from subcultured blood culture-positive bottles as samples. We compared this method, referred to as “Q Direct Method,” with our developed method using samples pretreated with Sputazyme, known as “Our Method.” Of the 150 samples, 84 were Staphylococcus aureus strains (48 methicillin-sensitive [MSSA] and 36 methicillin-resistant [MRSA]), and 66 were coagulase-negative staphylococci (CNS) strains (30 methicillin sensitive [MSCNS] and 36 methicillin-resistant [MRCNS]). For S. aureus, the Q Direct Method exhibited 97.2% sensitivity, 100% specificity, 98.8% reproducibility, and a 0.98 kappa statistic. In contrast, Our Method showed 100%, 100%, 100%, and 1 for each parameter. Concerning CNS, the Q Direct Method displayed 52.8% sensitivity, 100% specificity, 74.2% reproducibility, and a 0.50 kappa statistic. Our Method yielded 94.4%, 100%, 97.0%, and 0.94 for the respective parameters. Our findings suggest that our method of pretreating blood culture samples enables the rapid detection of PBP2’ from both S. aureus and CNS with a level of reproducibility comparable to the standard method.