[1438] Are Routine Anaerobic Blood Cultures Necessary?

Anna T Vischio, Amrita Pandit, Jillian Seifert, Laura Ovittore, Shawn Tittle, Jessica L Dodge. Danbury Hospital, Danbury, CT

Background: There has been a decline in the percentage of positive blood cultures yielding anaerobic organisms according to the medical literature. In order to assess whether or not it would be clinically safe and cost effective to draw only aerobic bottles during routine blood culture draws, we analyzed our laboratory data. Correctly diagnosing sepsis can have favorable results for the patient and also positive financial results for the hospital. A typical case of severe sepsis costs $25,000 per patient, corresponding to approximately $17 billion annually. If patients progress to septic shock and multiple organ dysfunction expensive therapeutic, diagnostic interventions and longer hospital stays would be required. The average cost of a positive anaerobic blood culture is $17.37 which includes $2.87 per bottle, $7.50 for technician time and $7.00 to run a confirmation panel on the Siemens MicroScan WalkAway 96 Plus ®.
Design: From January 2010 to May 2010, microbiology laboratory records of all blood cultures (3,769) were analyzed from both outpatient and inpatients at our institution.
Results: Organisms were isolated from 257 of 3,769 sets (positivity rate 6.8%): Forty-eight (48) were determined to be contaminants (1.9%). Therefore, 209 were considered clinically important. Of these, 17 (8.1%) were detected during anaerobic incubation and 43 (20.8%) were detected during aerobic incubation. The rest of the isolates (150) were detected during both aerobic and anaerobic incubation.

(Table 1) Isolates That Only Grew In Anaerobic Blood Culture Bottles
Faculatative AnaerobesObligate Anaerobes
Lactobacillus sp. (2)Bacteroides sp. not fragilis (1)
Staphylococcus aureus (2)Bacteroides fragilis (1)
Escherichia coli (4)Bacteroides fragilis species (1)
Pseudomonas aeruginosa (1)Peptostreptococcus (1)
Streptococcus agalactiae (1) 
Enterococcus faecalis (1) 
Escherichia fergusonii (1) 
Citrobacter freundii (1) 

Conclusions: It would not be clinically safe or cost effective to eliminate anaerobic blood culture bottles. We would have missed 17 clinically important bacteremias (8.1%) that could have harmed patients and led to overall higher costs. In this study, predominately facultative anaerobes were isolated from the anaerobic blood culture bottles (13 of 17). The BD BACTEC Lytic/10 Anaerobic/F Culture Vials system used at our institution utilizes .26% saponin, a detergent that lyses red and white blood cells, enabling the recovery of some bacteria that would not have grown in aerobic culture bottles.
Category: Infections

Wednesday, March 2, 2011 1:00 PM

Poster Session VI # 235, Wednesday Afternoon


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