Abstract
Delayed entry of blood culture bottles is frequent in consolidated laboratories. A retrospective study evaluated time from insertion to detection and total detection time as a function of preincubation time, and we prospectively looked for false negative results. 69,604 blood culture bottles were reviewed for preincubation time, incubation time and total detection time. Positive cultures for specific bacterial subtypes were reviewed to assess the effect of preincubation time on likelihood of detection. 492 negative blood cultures were prospectively tested by 16S RNA PCR and Staphylococcus-specific PCR for the presence of bacterial DNA. Mean preincubation time for samples collected within the city-limits was 3.94 h versus 9.49–18.89 h for other client sites. Higher preincubation times were partially mitigated by a lower incubation time, with an overall increase in total detection time. A lower odds ratio of recovery of Staphylococcus spp was identified, but not confirmed by terminal subcultures and molecular assays. Prolonged preincubation of blood cultures affects total detection time despite a reduction in incubation time. Successful centralization of microbiological services may depend upon optimization of courier routes for inoculated blood culture bottles. Our data supports consideration for an increase in suggested maximum preincubation times.
Highlights
Abbreviations analysis of variance (ANOVA) Analysis of variance CHEO Children’s Hospital of Eastern Ontario DNA Deoxyribonucleic acid EORLA Eastern Ontario Regional Laboratory Association incubation time (INC) Incubation time MALDI-TOF MS Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry MRSA Methicillin-resistance Staphylococcus aureus PCR Polymerase chain reaction RMRL Regional Microbiology Reference Laboratory RNA Ribonucleic acid total detection time (TDT) Total detection time
Laboratory consolidation in the healthcare system has been a reality since the 1970s, and the phenomenon has increased over time with core laboratories, often located in tertiary centers, offering microbiology diagnostic services to surrounding smaller community hospitals
Median preincubation time increased as a function of the distance traveled, which explained approximately 60% of the variation noted between sites (R2 = 0.593) (Fig. 1)
Summary
Abbreviations ANOVA Analysis of variance CHEO Children’s Hospital of Eastern Ontario DNA Deoxyribonucleic acid EORLA Eastern Ontario Regional Laboratory Association INC Incubation time MALDI-TOF MS Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry MRSA Methicillin-resistance Staphylococcus aureus PCR Polymerase chain reaction RMRL Regional Microbiology Reference Laboratory RNA Ribonucleic acid TDT Total detection time. Laboratory consolidation in the healthcare system has been a reality since the 1970s, and the phenomenon has increased over time with core laboratories, often located in tertiary centers, offering microbiology diagnostic services to surrounding smaller community hospitals. These efforts have been driven by both expected cost efficiency and improvement in patient care[1,2]. Preincubation of delayed blood culture bottles at 35-37oC prior to entry in continuous-monitoring blood culture system is not recommended, and neither is the storage of inoculated bottles at 4oC13 These suggestions all aim to maximize bacterial recovery and avoid the reporting of false negative results. A diminution in bacterial recovery has only been documented following > 24 h delayed entry for bottles held at room temperature, mainly for isolates of Streptococcus pneumoniae after delayed entry > 12 h with the BACTEC s ystem[5]
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