[Diagnostic reliability of anaerobic blood cultures in bacteremias from a critical care unit].
OBJECTIVE
This is a descriptive study of bacteraemias diagnosed in ICU with an analysis of the diagnostic reliability of anaerobic blood cultures.


METHODS
Analysis of all positive blood cultures in an Intensive Care Unit from May 2005 to October 2007.


RESULTS
The overall incidence of true bacteraemia was 6,1% of admissions. Out of 100 patients, there were 73 bacteraemias and 52 contaminated cultures. Samples with contaminated cultures were drawn 6,27 days earlier (CI 95% 0,61-11,94 Sig:0,03) than true bacteraemia. Most frequent micro organisms were cocci gram positive: 43 cases (58,9%) (coagulase-negative staphylococci was the most frequent: 30 or 41% of all bacteraemia)) Sig=0,001 in relation with gram negatives. Anaerobic micro organisms were not detected. Candidemias were found in 10 cases (13,7%). The most frequent causes of bacteraemia in this study were catheter-related infections with 36 cases (49,3% Sig<0,005), followed by digestive origin infections in 14 (19,2%). Of all bacteremic episodes (73 bacteraemia), 66 (90,4%) were isolated in aerobic blood cultures, and 58 (79,5%) were in anaerobic ones, with a difference of 10,9% Sig:0,06. When only intrahospitalary bacteraemias were analyzed, there was a difference of 13,56% of more yields in aerobic blood cultures; Sig:0,04 (IC 95% 0,8%-26%)). Candidemias were isolated only in aerobic blood cultures; Sig:0,001. When analyzing coagulase negative staphylococci, there were 30 bacteraemias and 41 contaminated samples. 62 (87,3%) were isolated in aerobic blood cultures and 50 (70,4%) in anaerobic ones, with a difference of 16,9% Sig=0,01,CI 95%(3%-30%).


CONCLUSIONS
In the Critical Care Unit, it would be possible to change the anaerobic blood cultures by aerobic ones to diagnose bacteraemias of intrahospitalary acquisition. This fact should be analyzed with others studies.
Medicina Interna-Infecciosas, Hospital Universitario de Fuenlabrada, Madrid, España. jruiz.hflr@salud.madrid.org
José Manuel
JM
Ruiz-Giardín
Mercedes
M
Alonso
Jerónimo
J
Jaquetti
Susana
S
Sánchez
Teresa
T
Saldaña
Antonio
A
Zapatero
D016470:Bacteremia / Q000097:blood* / Q000175:diagnosis* / Q000382:microbiology; D001421:Bacteria, Anaerobic / Q000254:growth & development* / Q000302:isolation & purification; D001431:Bacteriological Techniques; D003422:Critical Care; D003470:Culture Media; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results
D003470:Culture Media