Severity of pneumococcal pneumonia associated with genomic bacterial load.
BACKGROUND
There is a clinical need for more objective methods of identifying patients at risk for septic shock and poorer outcomes among those with community-acquired pneumonia (CAP). As viral load is useful in viral infections, we hypothesized that bacterial load may be associated with outcomes in patients with pneumococcal pneumonia.


METHODS
Quantification of Streptococcus pneumoniae DNA level by real-time polymerase chain reaction (rt-PCR) was prospectively conducted on whole-blood samples from a cohort of 353 patients who were displaying CAP symptoms upon their admission to the ED.


RESULTS
CAP caused by S pneumoniae was documented in 93 patients (36.5% with positive blood culture findings). A positive S pneumoniae rt-PCR assay finding was associated with a statistically significant higher mortality (odds ratio [OR], 7.08), risk for shock (OR, 6.29), and the need for mechanical ventilation (MV) [OR, 7.96]. Logistic regression, adjusted for age, sex, comorbidities, and pneumonia severity index class, revealed bacterial load as independently associated with septic shock (adjusted odds ratio [aOR], 2.42; 95% CI, 1.10 to 5.80) and the need for MV (aOR, 2.71; 95% CI, 1.17 to 6.27). An S pneumoniae bacterial load of >or= 10(3) copies per milliliter occurred in 29.0% of patients (27 of 93 patients; 95% CI, 20.8 to 38.9%) being associated with a statistically significant higher risk for septic shock (OR, 8.00), the need for MV (OR, 10.50), and hospital mortality (OR, 5.43).


CONCLUSIONS
In patients with pneumococcal pneumonia, bacterial load is associated with the likelihood of death, the risk of septic shock, and the need for MV. High genomic bacterial load for S pneumoniae may be a useful tool for severity assessment.
Rello
Jordi
J
Critical Care Department, Hospital Universitari Joan XXIII, Tarragona, Spain; University Rovira i Virgili, IISPV, Tarragona, Spain; Centro de Investigacíon Biomedica en Red Enfermedades Respiratorias (CIBERes), Tarragona, Spain. Electronic address: jrello.hj23.ics@gencat.cat.
Lisboa
Thiago
T
Critical Care Department, Hospital Universitari Joan XXIII, Tarragona, Spain; University Rovira i Virgili, IISPV, Tarragona, Spain; Centro de Investigacíon Biomedica en Red Enfermedades Respiratorias (CIBERes), Tarragona, Spain.
Lujan
Manel
M
Centro de Investigacíon Biomedica en Red Enfermedades Respiratorias (CIBERes), Tarragona, Spain; Hospital de Sabadell, Sabadell, Spain.
Gallego
Miguel
M
Centro de Investigacíon Biomedica en Red Enfermedades Respiratorias (CIBERes), Tarragona, Spain; Hospital de Sabadell, Sabadell, Spain.
Kee
Cordelia
C
School of Medicine and Pharmacology, University of Western Australia, Perth, WA, Australia.
Kay
Ian
I
Department of Microbiology and Infectious Diseases, Royal Perth Hospital, Perth, WA, Australia.
Lopez
Diego
D
Centro de Investigacíon Biomedica en Red Enfermedades Respiratorias (CIBERes), Tarragona, Spain; Fundación Jimenez Diaz, Madrid, Spain.
Waterer
Grant W
GW
School of Medicine and Pharmacology, University of Western Australia, Perth, WA, Australia.
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004269:DNA, Bacterial / Q000032:analysis* / Q000235:genetics; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011018:Pneumonia, Pneumococcal / Q000382:microbiology* / Q000401:mortality; D011446:Prospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012307:Risk Factors; D012720:Severity of Illness Index; D013296:Streptococcus pneumoniae / Q000302:isolation & purification*
D004269:DNA, Bacterial