Time for a culture change? Suboptimal compliance with blood culture standards at a district hospital in Cape Town

Abstract

Background. The benchmark for contaminated blood cultures (BCs) is 3%. The South African (SA) guideline aims to optimise BC yield and reduce contamination. Data on BC collection practices in SA since the publication of the 2010 SA guideline are lacking. Objective. To evaluate compliance with the national guideline for the optimal use of BCs and determine the BC contamination rate at a local district hospital.Method. An audit of compliance with 22 BC standards was conducted at a district hospital in Cape Town, SA. Standards were evaluated by reviewing clinical and laboratory data and by a clinician questionnaire. Results. Of the 425 BCs reviewed, 12.5% had positive growth, and 4.5% grew contaminants. Only 33% of BC bottles contained the recommended fill volume of 8 -10 mL, and 96.9% of patients had a single BC within a 24-hour period. Of all the BCs, only 7.8% had a combined blood volume of at least 20 mL. The yield of pathogens in BCs collected after antibiotic exposure was 4.9% compared with 7.5% for those cultures with no prior antibiotic exposure (p=0.3). The overall median needle-to-incubator transport time was 11 hours 25 minutes. Conclusion. The BC contamination rate was high and compliance with most standards was variable or not met. The findings may not be generalisable to other hospitals, and we recommend that each institution reviews its own BC practices. Recommendations made to hospital staff included a re-audit following implementation of these recommendations.

Best Practices of Blood Cultures in Low- and Middle-Income Countries

“…Contamination of blood cultures remains a substantial problem, with contamination rates as high as 10% even in many HICs (177). Contamination is suspected to be more frequent in LMICs, with some settings (i.e., South Africa, Ghana, the Gambia, Malawi) indeed reporting very high contamination rates (178–181). The spectrum of contaminants in LMICs differs slightly to HICs; for example, more Bacillus species are seen in LMICs (178).…”

“…Contamination is suspected to be more frequent in LMICs, with some settings (i.e., South Africa, Ghana, the Gambia, Malawi) indeed reporting very high contamination rates (178–181). The spectrum of contaminants in LMICs differs slightly to HICs; for example, more Bacillus species are seen in LMICs (178). This finding suggests that contamination of blood cultures in LMICs commonly has the environment as a source, as Bacillus species are known to be present in dust and have been described in outbreaks of pseudo-bacteremia originating from the environment (182, 183).…”

Can the Xpert MRSA/SA BC assay be used as an antimicrobial stewardship tool? A prospective assay validation and descriptive impact assessment study in a South African setting

“…The clinicians in our setting favoured continuing antibiotic therapy if sepsis was the initial diagnostic consideration and CoNS was cultured, in the majority of patients. We attributed this nding at least in part, to the high rate of BC contamination in our setting (14), which may be regarded as having masked the presence of a true pathogen. Decisions regarding antibiotics are also governed by other factors not measured here, such as the clinical response to antibiotic therapy and additional test results.…”

Can the Xpert MRSA/SA BC assay be used as an antimicrobial stewardship tool? A prospective assay validation and descriptive impact assessment study in a South African setting

“…We initially expected this assay to be of most use in reducing antibiotic therapy in patients with CoNS, as has been reported previously [ 13 ], but this finding was not replicated. The vast majority of CoNS bloodstream isolates were regarded as being not clinically significant in this cohort, in keeping with the high rate of blood culture contamination in our setting [ 14 ]. Clinicians thus disregarded this “contaminated” result and continued the empiric antibiotic regimen that had been commenced based on the initial clinical assessment.…”