Sterile blood culture (BC) collection procedures are important to prevent the consequences of contamination, namely, prolonged patient hospitalisation, unnecessary antimicrobial exposure and an increase in hospital costs. Blood culture contamination rates were determined at different hospitals in the Cape Metropole over a 3-year period. Study findings showed that contaminated BCs have a financial impact on the healthcare system and contamination rates remain above accepted international standards, except in the presence of a phlebotomist team. High BC contamination rates might be reduced by the implementation of cost-effective educational intervention programmes, which reminds healthcare workers to collect BC samples aseptically.
Globally blood stream infections result in high morbidity and an overall crude mortality of 15% – 30%.
An intervention such as teaching healthcare professionals how to take blood samples aseptically may reduce the rates of BC contamination and minimise wasteful expenditure.
The National Health Laboratory Service (NHLS) laboratory is situated within GSH, Cape Town, SA. This laboratory provides services to approximately 80% of the population in the hospital’s drainage area (Southern, Klipfontein, Mitchells Plain and Western health districts), with numerous facilities including 58 primary healthcare facilities, 3 district-, 2 regional- and 2 tertiary-level hospitals and 1 private facility. The private academic hospital is a collaboration between the private healthcare sector, the University of Cape Town and GSH. Through this collaboration, the NHLS at GSH receives and processes a portion of their specimens. All BCs submitted to GSH, NHLS were included in the study and only processed at this laboratory. Both hospitalised patients and those presenting from a community setting were included in the analysis.
A contaminated BC was defined as a sample containing 1 or more of the following ‘skin flora’: CoNS,
Blood culture data between 01 January 2016 and 31 December 2018 were retrospectively extracted from the laboratory information system at the NHLS, based at GSH. The rates of BC contamination in GSH were compared with that of surrounding health facilities on a department and hospital level. Institutional contamination rates were defined as the number of contaminated BCs divided by the total amount of BCs taken. The contaminating microorganisms were identified amongst the total amount of BCs collected during the period investigated.
Shapiro–Wilk and Levene’s test were used to confirm normal distribution of data and homogeneity of variance amongst groups. Analysis of variance (ANOVA) was run to examine the effect of department, age, and hospital level on BC contamination rates. A
Only direct item costs (syringes, needles, sterile cloves, cleaning solution, cleaning packs and blood culture bottle) and laboratory expenses (culture incubation, media plates, biochemical reagents and microscopy) of analysing individual contaminated samples were considered in the cost analysis. This excluded any additional costs related to patient management as a result of a contaminated BC sample. Cost analysis was done on a department and hospital level from accumulative data over a 3-year period.
Ethical approval to conduct the study was obtained from the Research Ethics Committee (HREC: Ref. No. 347/2019) of the University of Cape Town, as well as GSH, Department of Health, Western Cape.
Over a 36-month period (01 January 2016–31 December 2018), the BC contamination rate in GSH ranged from 2.2% to 4.5% per month, with an average BC contamination rate of 3.3% over the 3 years. The contamination rate was below 3% during 10 of the 36 months of the study period. In comparison, a private hospital facility with a phlebotomist team had an average contamination rate of 1.3%, a tertiary-level hospital other than GSH 4.3%, secondary-level hospitals 4.5% and district hospitals 6.7%. The district-level hospitals had 26 months with contamination rates twice above the CLSI standards, whilst the phlebotomist team only crossed that barrier once during a 3-year period (
Blood culture contamination rates in different level hospitals with and without the educational intervention compared to the Clinical and Laboratory Institute International standard benchmark of 3%, between 01 January 2016 and 31 December 2018.
There was no significant interaction between the effects of department and age (
(a) Blood culture contamination rates at different level hospitals and departments in the Cape Town Metropole; (b) Total amount of blood cultures collected with the proportion of contaminating microorganisms cultured; (c) Contaminating microorganisms from processed blood cultures; (d) Blood culture collection consumables and laboratory culturing costs at the National Health Laboratory Service, Groote Schuur Hospital. The study period is between 01 January 2016 and 31 December 2018. The private hospital facility has no emergency or trauma unit. Primary healthcare facilities have no intensive care units.
In total, 4279 (77.6%) of the contaminating microorganisms cultured (
The cost for processing contaminated BCs over the 3 years amounted to R1 017 576. From this amount R903 965 was allocated to a ward assigned. Adult patient samples accounted for 73.5% (R664 460) of these costs. Tertiary-level hospitals carried the bulk of the expenses at R367 062 (40.6%), whilst R531 165 (58.8%) was allocated towards emergency and trauma units for processing contaminated samples (
The average BC contamination rate in GSH was 3.3%, which is above the CLSI benchmark of 3%. Some studies have suggested that higher contamination rates are acceptable in teaching facilities.
The contamination rates in the private hospital setting with a phlebotomist team were the lowest, with an average rate of 1.3% over the 3 years investigated. The use of a dedicated phlebotomist team leads to a decrease in BC contamination rates as well as a reduction in the associated costs.
Coagulase-negative staphylococci were the main contaminating organisms found in our study, which is in line with other BC investigations done in SA and around the world.
Previous studies have shown that contamination rates are more frequent in the paediatric population.
An intern orientation programme with infection prevention and control (IPC) lectures has been presented at the beginning of medical internships at GSH for the last 10 years. The interns also received an informal registrar training course on how to take BC samples aseptically throughout the year. Educational programmes have been proven to be effective in decreasing BC contamination rates whilst being cost-effective.
Blood culture contamination has a significant impact on pharmacy and laboratory costs.
This study has limitations mainly because of the retrospective study design, as the analysis relied on the integrity of the data extracted. No data are available for comparison before the educational interventions that were implemented at GSH. Although educational interventions have shown in the literature to reduce BC contamination rates and save costs, no multivariate analysis was performed to exclude confounding factors in this study, which may have contributed to the low rates of BC contamination at GSH. Future research on this topic should be dedicated to this aspect. The current data look at a department level and not at ward levels; therefore, interventions directed towards meeting discipline-specific challenges could not be developed. In addition, we did not investigate the cause(s) of BC contamination in each department or hospital. Finally, cost analysis or auditing was not done beyond the consumables and laboratory processing costs.
Overall, BC contamination rates continue to be above the accepted international range amongst healthcare institutions in the Western Cape province, SA. Staff education is central to the reduction of BC contamination, especially in settings without a dedicated phlebotomist team. The low BC contamination rates at GSH (tertiary institution) may be related to the educational IPC interventions and possibly the collection of BCs under the guidance of senior staff. Teaching IPC and sterile BC collection should include variable creative methods (especially in low-resource settings), such as ward posters, videos and one-on-one staff interactions, with metrics in place to measure their impacts. Amongst all the units, the emergency and trauma sections were found to have the highest BC contamination rates, with a large number of BC samples collected. This justifies the need for low-cost, multifaceted interventions in this section of the hospital to reduce contamination rates and lessen the possible additional costs on the healthcare system.
The authors have declared that no competing interest exists.
All authors contributed equally to this work.
This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.
The data that support the findings of this study are available upon reasonable request from the corresponding author (C.J.O.), with National Health Laboratory Service approval. The data are not publicly available due to information that could compromise the interest of healthcare facilities.
The views and opinions expressed in this article are those of the authors and do not necessarily reflect the official policy or position of any affiliated agency of the authors.