Quantitative Culture of Endotracheal Aspirates in the Diagnosis of Ventilator-Associated Pneumonia in Patients With Treatment Failure

doi:10.1378/chest.122.2.662

Chest

Volume 122, Issue 2, August 2002, Pages 662-668

https://doi.org/10.1378/chest.122.2.662 Get rights and content

Study objective

To study the correlation of bacteriology between quantitative cultures of protected specimen brush (PSB), BAL, and quantitative endotracheal aspirate (QEA) in ventilator-associated pneumonia (VAP) patients with treatment failure.

Design

Prospective observational clinical study.

Setting

A 15-bed medical ICU of tertiary medical center.

Patients

Forty-eight patients receiving mechanical ventilation with clinical suspected VAP who had been treated with antibiotics for at least 72 h without improvement.

Intervention

QEA, PSB, and BAL were performed with patients receiving antibiotics. The diagnostic thresholds for QEA, PSB, and BAL were 10⁵, 10³, and 10⁴ cfu/mL, respectively.

Measurements and results

Microbial culture findings were positive in 24 BAL samples (50%), in 23 PSB samples (48%), and in 28 QEA samples (58%). The correlations between of QEA vs PSB and QEA vs BAL were significant (ρ = 0.567 and ρ = 0.620, p < 0.01, respectively). The most commonly isolated microorganisms were Acinetobacter baumannii (27%), Staphylococcus aureus (24%), Stenotrophomonas maltophilia (15%), and Pseudomonas aeruginosa (10%). Using the predetermined criteria, bacterial pneumonia was diagnosed in 28 of 48 suspected VAP episodes based on PSB and/or BAL results. The diagnostic efficiency of QEA at threshold of 10⁵ cfu/mL had a sensitivity of 92.8% and a specificity of 80%.

Conclusions

QEA correlated with PSB and BAL in patients with suspected VAP who responded poorly to the existent antibiotic treatment. QEA missed only two cases of bacterial pneumonia diagnosed by invasive PSB and/or BAL with acceptable sensitivity and specificity. More importantly, QEA is noninvasive and easily repeatable. Early use of QEA is helpful to clinical physicians in decision making with regard to antibiotics use.

Section snippets

Materials and Methods

This study was conducted between December 1997 and June 1999 in the medical ICU of Mackay Memorial Hospital, a 15-bed ICU for adult patients from multiple disciplines. During the study period, a total of 596 patients were admitted to the medical ICU. Patients who had received mechanical ventilation for > 72 h and received antibiotic therapy for ≥ 72 h for either pulmonary or extrapulmonary conditions before development of a new and/or progressive radiographic infiltrates were included. Patients

Results

From December 1997 to June 1999, 48 patients were prospectively studied. The study group consisted of 26 men and 22 women with a mean age of 65.3 ± 15.2 years (range, 33 to 82 years) and mean admission APACHE (acute physiology and chronic health evaluation) score of 21 ± 6 (range, 16 to 30). The primary underlying diseases for admission to the ICU were COPD with acute exacerbation (n = 6, 12%), cardiogenic emergency (n = 5, 10%), sepsis with acute respiratory failure (n = 10, 21%), pneumonia (n

Discussion

The results of this study showed that the quantitative cultures of endotracheal aspirates were comparable to those using invasive bronchoscopic methods in patients already receiving antibiotics. There was a total agreement in bacteriology between QEA and combined PSB/BAL on 37 patients (19 patients with positive culture findings and 18 patients with negative culture findings). QEA at the cutoff point of 10⁵ cfu/mL can detect pneumonia with a sensitivity of 92.8%, a specificity of 80%, and a

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Several guidelines base the empirical therapy of ventilator-associated pneumonia (VAP) on the time of onset. However, there is emerging evidence that the isolated microorganisms may be similar regardless of onset time. This study evaluated the characteristics and outcomes of VAP with different onset times. All of the mechanically ventilated patients admitted to the ICU of a 900-bed tertiary-care hospital between 01/08/2003 and 31/12/2010 were prospectively followed for VAP development according to the National Healthcare Safety Network criteria. The patients were categorized into four groups: EO if VAP occurred within 4 days of intubation and hospital admission; LO if VAP occurred after 4 days of admission; EL if VAP occurred within 4 days of intubation, but after the fourth hospitalization day; and LL if VAP occurred after the fourth day of intubation and hospitalization. Out of the 394 VAP episodes, 63 (16%) were EO episodes, 331 (84.0%) were LO episodes, 40 (10.1%) were EL episodes and 291 (73.1%) were LL episodes. The isolated microorganisms were comparable among the four groups, with a similar rate of potentially multidrug resistant organisms in the EO-VAP (31.7%), LO-VAP (40.8%), EL-VAP (37.5%) and LL-VAP (43.3%) samples. The hospital mortality was 24% for EO-VAP cases, 28% for LO-VAP cases, 40% for EL-VAP cases and 49% for LL-VAP cases. However, in the adjusted multivariate analysis, neither LO-VAP, EL-VAP nor LL-VAP was associated with an increased risk of hospital mortality compared with EO-VAP (OR, 0.86 95% CI, 0.34–2.19; 1.22; 95% CI, 0.41–3.68, and 0.95; 95% CI, 0.43–2.10, respectively). In this study, the occurrence of potential multidrug resistant pathogens and the mortality risk were similar regardless of VAP timing from hospital admission and intubation. The bacterial isolates obtained from the VAP cases did not follow an early vs. late-onset pattern, and thus, these terms may not be clinically helpful.
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Citation Excerpt :
One end of the mucus extractor was connected to the infant feeding tube and the other end to an open suction pump. Both specimens were immediately transported to the laboratory and processed according to the standard protocol [6]. All the bacterial isolates were identified to species level by standard biochemical tests, and their antibiotic susceptibility testing was performed by the Kirby–Bauer disk diffusion method on Mueller–Hinton agar as per the guidelines of the Clinical and Laboratory Standards Institute [7].
To determine primarily (1) the incidence of ventilator-associated pneumonia (VAP) among ventilated patients aged 1 month to 12 years and secondarily (2) the risk factors for VAP and (3) common organisms causing VAP.
Prospective study in a tertiary care center in India. Consecutive ventilated patients aged ≥1 month and ≤12 years and requiring mechanical ventilation (MV) for ≥48 hours were included after written informed parental consent. For the diagnosis of VAP, National Nosocomial Infections Surveillance System criteria of 1996 were used.
Incidence of VAP among patients aged 1 month to 12 years was 36.2% (38/105; 95% confidence interval [CI]: 27, 46). In unconditional logistic regression analysis controlling for the presence of underlying illnesses, risk factor for VAP was >4 days of MV (adjusted odds ratio, 3.76; 95% CI: 1.41, 10.02; P = 0.008). Reintubation within 72 hours of extubation and more than two attendants at the time of recruitment showed increased tendency for the development of VAP but did not reach statistical significance. Endotracheal and endobronchial aspirates were positive for organism in 19.05% (20/105) and 37.14% (39/105) of patients, respectively.
Almost one-third of ventilated patients develop VAP. Vigilance for the development of VAP has to be kept on those requiring >4 days of MV. Klebsiella and Staphylococcus aureus were common bacterial isolates in such patients.
Carbapenem-Resistant Klebsiella pneumoniae Among Patients with Ventilator-Associated Pneumonia: Evaluation of Antibiotic Combinations and Susceptibility to New Antibiotics
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Chest

Clinical Investigations in Critical CareQuantitative Culture of Endotracheal Aspirates in the Diagnosis of Ventilator-Associated Pneumonia in Patients With Treatment Failure

Study objective

Design

Setting

Patients

Intervention

Measurements and results

Conclusions

Section snippets

Materials and Methods

Results

Discussion

Infect Dis Clin North Am

Chest

Chest

Am J Med Sci

Chest

Chest

Chest

Invasive diagnostic testing should be routinely used to manage ventilated patients with suspected pneumonia

Am J Respir Crit Care Med

The standardization of bronchoscopic techniques for ventilator-associated pneumonia

Chest

The standardization of criteria for processing and interpreting laboratory specimens in patients with suspected ventilator-associated pneumonia

Chest

Evaluation of the protected brush catheter and bronchoalveolar lavage in the diagnosis of nosocomial pneumonia

Intensive Care Med

Invasive and noninvasive strategies for management of suspected ventilator-associated pneumonia: a randomized trial

Ann Intern Med

Clinical Investigations in Critical Care
Quantitative Culture of Endotracheal Aspirates in the Diagnosis of Ventilator-Associated Pneumonia in Patients With Treatment Failure