RESUMEN
OBJECTIVE: The aim of the present study was to determine if the quantification of bacterial 16S rDNA could be clinically useful in predicting patients at increased risk of developing septic shock. METHODS: A retrospective study of patients with positive blood cultures taken on arrival to the ED. An EDTA sample was collected simultaneously with blood cultures and assayed by polymerase chain reaction to quantitate the bacterial 16S rDNA load. Descriptive and clinical data were collected from the medical record and this was blinded to the 16S rDNA result. Subsequently, the 16S rDNA result was compared with illness severity markers including septic shock and death to determine the relationship between the 16S rDNA load and illness severity. RESULTS: 98 patients (mean age 61 ± 20 years, range 18-92) with positive blood cultures were studied, most commonly growing Escherichia coli (n= 25) and Staphylococcus aureus (n= 23). 16 (16%) died. There were 42 (43%) 16S rDNA positive patients. A high 16S rDNA load was associated with an increased risk of developing delayed septic shock (OR 21.9, 95% CI 2.5-192.6) in comparison with either a low or negative 16S rDNA load; with a mortality OR 4.6 (95% CI 0.9-23.5). CONCLUSIONS: The quantitative assay for 16S rDNA might be a useful screening tool to detect severe sepsis in those whom it might not be clinically suspected. However, prospective studies are required to further assess the clinical usefulness of this assay.
Asunto(s)
ADN Bacteriano/análisis , ARN Ribosómico 16S/análisis , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa/métodos , Sepsis/diagnóstico , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Sepsis/microbiología , Sepsis/mortalidad , Choque Séptico/prevención & control , Adulto JovenAsunto(s)
ADN Bacteriano/análisis , Neumonía Neumocócica/diagnóstico , Reacción en Cadena de la Polimerasa/normas , Streptococcus pneumoniae/genética , Líquido del Lavado Bronquioalveolar/microbiología , Diagnóstico Diferencial , Humanos , Neumonía Neumocócica/microbiología , Sensibilidad y Especificidad , Esputo/microbiología , Streptococcus pneumoniae/aislamiento & purificaciónRESUMEN
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). CONCLUSION: 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.
Asunto(s)
ADN Bacteriano/análisis , Neumonía Neumocócica/microbiología , Streptococcus pneumoniae/aislamiento & purificación , Adulto , Anciano , Anciano de 80 o más Años , ADN Bacteriano/genética , Interpretación Estadística de Datos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Neumonía Neumocócica/mortalidad , Estudios Prospectivos , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Factores de Riesgo , Índice de Severidad de la EnfermedadRESUMEN
We assessed a real-time quantitative polymerase chain reaction (PCR) assay targeting the lytA and ply gene of Streptococcus pneumoniae. Both assays were applied to whole blood samples from 28 adult patients with community-acquired pneumonia. Our findings suggest the lytA PCR is more sensitive, and the quantitative aspect of the assay shows promise as an aid to clinical judgment.