Distinguishing coagulase-negative Staphylococcus bacteremia from contamination using blood-culture positive bottle detection pattern and time to positivity.

Abstract

AIM:

Detection of coagulase-negative Staphylococcus in blood culture may be a result of either bacteremia or contamination. This often leads to diagnostic uncertainly. Our objective was to develop a method for differentiating whether a coagulase-negative Staphylococcus sp. positive blood culture represents bacteremia or contamination based on positive bottle detection pattern and time to positivity (TTP).

METHODS:

This study included 155 and 51 adults with positive blood cultures for Staphylococcus epidermidis and Staphylococcus hominis, respectively, over a three-year period from 2016 to 2018. Positive blood culture cases were categorized as either bacteremia or contamination based on the clinically available information, and the detection pattern and TTP in each category were investigated.

RESULTS:

A total of 57, 92, and 6 S. epidermidis positive blood cultures were categorized as bacteremia, contamination, and undetermined, respectively, whereas 15 and 36 S. hominis positive blood cultures were categorized as bacteremia and contamination, respectively. For positive blood cultures categorized as bacteremia, all four bottles in two sets of blood cultures were positive in 47/47 S. epidermidis and 14/14 S. hominis, respectively, whereas either one bottle in each of two sets or three bottles in two sets were positive in 10/19 S. epidermidis and 1/4 S. hominis, respectively; most of those TTPs were <48 h. Among them, the TTP in catheter-related blood stream infection was <24 h.

CONCLUSION:

Although clinical assessment is crucial to differentiate between bacteremia and contamination, a combination of positive bottle detection pattern and TTP is a valuable diagnostic auxiliary tool.

• Authors: Sayuri Osaki, Kentaro Kikuchi, Yuki Moritoki, Chiyoko Motegi, Sho Ohyatsu, Tomoyuki Nariyama, Kotaro Matsumoto, Hiromichi Tsunashima, Tomohiro Kikuyama, Juri Kubota, Kozue Nagumo, Hikari Fujioka, Ryoko Kato, Yuji Murakawa
• Journal: Journal of infection and chemotherapy : official journal of the Japan Society of Chemotherapy (J Infect Chemother) Vol. 26 Issue 7 Pg. 672-675 (Jul 2020) ISSN: 1437-7780 [Electronic] Netherlands
• PMID: 32131983 (Publication Type: Journal Article)
• Copyright: Copyright © 2020 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Topics

• Adult
• Bacteremia (diagnosis, microbiology)
• Blood Culture (instrumentation, standards, statistics & numerical data)
• Catheter-Related Infections (blood, diagnosis)
• Equipment Contamination (prevention & control, statistics & numerical data)
• Humans
• Predictive Value of Tests
• Retrospective Studies
• Specimen Handling (instrumentation, standards)
• Staphylococcal Infections (blood, diagnosis, microbiology)
• Staphylococcus epidermidis (isolation & purification)
• Staphylococcus hominis (isolation & purification)