Recovery and time to growth of isolates in blood culture bottles: comparison of BD Bactec Plus Aerobic/F and BD Bactec Plus Anaerobic/F bottles.
BACKGROUND
This study was done to compare the growth of pathogens in paired aerobic/anaerobic blood culture bottles versus the use of only aerobic bottles, and to analyze the time to growth in both atmospheres.


METHODS
We retrospectively evaluated the results of all blood cultures collected over a 2-y period for the diagnosis of central venous catheter-related bloodstream infections or other severe infections in oncology patients.


RESULTS
Among the 487 isolates, 174 (35.7%), all aerobic, grew only in the aerobic bottle; 250 (51.3%), all aerobic, grew in both bottles; and 63 (12.9%) grew only in the anaerobic bottle, of which 24 were anaerobic and 39 were aerobic microorganisms (8% of positive blood cultures). Of these 39 aerobic microorganisms, 12 were Gram-negative, 17 staphylococci (4 were Staphylococcus aureus), 5 streptococci, 2 Gram-positive bacilli, and 3 mixed growth. Though the mean time to positivity of pathogens grown in both atmospheres was significantly lower in the aerobic bottle than in the anaerobic bottle, in 71 cases (28.4%) the pathogens developed earlier in the anaerobic bottle than in the aerobic bottle - in 36 of these cases at least 1 h earlier, which is significant for starting targeted therapy.


CONCLUSIONS
The use of paired aerobic/anaerobic blood culture bottles allowed the diagnosis of a percentage of bacteraemia due to either anaerobic or aerobic pathogens that would have been missed, as they grew only in the anaerobic atmosphere. Moreover in 8% of bacteraemia we identified a significant decrease in the time to detection, resulting in the opportunity to better manage the infections without an increase in costs.
From the Division of Laboratory Medicine, European Institute of Oncology , Milan , Italy.
Rita
R
Passerini
Maria Cristina
MC
Cassatella
Michela
M
Salvatici
Fabio
F
Bottari
Cristian
C
Mauro
Davide
D
Radice
Maria Teresa
MT
Sandri
D000332:Aerobiosis; D000693:Anaerobiosis; D016470:Bacteremia / Q000175:diagnosis* / Q000382:microbiology; D001419:Bacteria / Q000145:classification / Q000302:isolation & purification; D001431:Bacteriological Techniques / Q000295:instrumentation* / Q000379:methods / Q000706:statistics & numerical data; D003470:Culture Media; D006801:Humans; D009369:Neoplasms / Q000382:microbiology; D012189:Retrospective Studies; D013997:Time Factors
D003470:Culture Media