Early Diagnosis of Ventilator-Associated Pneumonia (Results)

22 Dec

Early Diagnosis of Ventilator-Associated Pneumonia (Results)Patients

One hundred thirty-two patients (mean age, 52±19 years; mean simplified acute physiologic score,14±4; 85 men and 47 women) were included. All were suspected of presenting nosocomial bacterial pneumonia: 163 BALs and PSBs were performed. The mean duration of mechanical ventilation was 15±4 days.

The following were primary indications for ventilatory support: postoperative respiratory failure (n=40), exacerbation of COPD (n=19), other pulmonary diseases (n=10), neurologic emergencies (n=8), head injuries (n=8), multiple organ failure (n=13), severe sepsis (n=17), multisystem trauma patients (n=45), and miscellaneous (n=3).The diagnosis of bacterial pneumonia was established in 56 cases; polymicrobial growth was seen in 48.2% of the cases (27/56). There was no bacterial pneumonia in 107 cases.

Tolerance of Bronchoscopy

All the bronchoscopies were accomplished without complications (no hypoxemia, no pneumothorax, no hemorrhage); we have not observed any major hemodynamic difficulties during or following the procedure in any of the patients.


Squanwus Epithelial Cells: None of the samples had more than 1% of squamous epithelial cells (Table 1).

Count of Total Cells: The count of total cells was significantly higher in control patients: 6,684±27,826 vs 5,113±4,983xl03/mL (p<0.001).

Count of PMNs: The count of PMNs in BAL fluid was significantly higher in the group with nosocomial pneumonia: 85±13% versus 73±24% (p<0.01).

Infected Cells: The count of ICs was made on 100 cells (Figs 1 and 2). The percentage of ICs was significantly higher in nosocomial pneumonia: 12.6±12% (95% confidence interval [Cl], 9.3 to 16) vs 1.1±3.4 (95% Cl, 0.49 to 1.8) (p<0.0001). An ROC curve was plotted: the AUC was 0.888; the curve was homogeneous without break.

The presence of ICs in 2% or more on the Giemsa stain corresponded to a sensitivity of 84%, a specificity of 80%, a positive predictive value of 69%, and a negative predictive value ot 90%. There was no correlation (Fig 3) between the percentage of ICs and quantitative cultures of PSB (r=0.25; p=0.06). Concordance between final diagnosis and IC count was 0.82 (Cohen kappa=0.063). Among the patients receiving antibiotics, sensitivity and specificity were, respectively, 82% and 77%; among the patients without antibiotics, 85% and 83%.


Microscopic Examination: A Gram’s stain was performed on all BAL samples. The sensitivity and the specificity of the presence of bacteria in BAL fluid for the diagnosis were, respectively, 92% and 76.5%; the positive and negative predictive values were, respectively, 69% and 91%. However, in terms of qualitative agreement, the concordance was poor: in 44% of the cases, Gram’s stain was partially right (for example, gram-negative bacilli on Gram’s stain and Staphylococcus aureus plus Pseudomonas aeruginosa on PSB cultures) or totally false (gram-negative bacilli on Gram’s stain and gram-positive on PSB cultures).

Final Diagnosis: In 163 procedures, we noted 107 cases without pneumonia and 56 cases with pneumonia (Table 2): 18 cases with gram-negative bacilli, 11 cases with gram-positive cocci (principally S aureus), and 27 were polymicrobial infections (gram-negative bacilli and gram-positive cocci).

Table 1—Analysis of Cellularity

Group Without Pneumonia (n=107)Group With Pneumonia (n=56)p Value
ICs, %1.1±3.412.6±12<0.0001
Total cells, xl03/mL6,684 ±27,8265,113±4,983<0.001
PMNs, %73±2485 ±13<0.01

Table 2—Main Bacteriologic Results in Infected Patients (continued)



BacteriaPSB Cultures, cfu/mLIC, %PMN, %Cells, 103/mL
1Escherichia coli500109517,280
Enterococcus faecalis103
M morganii500
2E coli10312754,500
P aeruginosa30
3S aureus10625904,370
Haemophilus influenzae104
Citrobacter spp100
4S aureus2xl0315753,430
P aeruginosa5xl03
5S aureus10011852,150
Klebsiella pneumoniae2.4xl03
Enterobacter spp40
6S aureus5xl065853,000
7H influenzae10635852,640
Enterobacter spp107
8H influenzae10614802,000
9E coli5 x10s29013,320
10S aureus5 x10s2901,568
11P aeruginosa10525959,200
Proteus vulgaris5xl04
S pneumoniae103
12Proteus mirabilis1072952,480
13S aureus1050804,480
14S aureus1033803,500
15H influenzae6xl03195640
H hemolyticus6xl03
S aureus3xl04
16P aeruginosa4xl038902,088
17E coli105508516,000
K pneumoniae103
H influenzae109
18Enterobacter spp10315851,480
N meningitidis106
19P aeruginosa1034595580
E cloacae100
S aureus105
20P aeruginosa1063901,300
21H influenzae1044836,300
22Proteus vulgaris4025802,380
S aureus5×10s
H influenzae103
23S pneumoniae104760500
H influenzae104
24S aureus10312805,760
25S aureus1054905,300
26E coli10510904,560
S aureus105
27M morganii1031905,100
28E coli1040803,120
29H influenzae108189519,600
S pneumoniae108
30S aureus1056902,020
31H influenzae10411951,820
S pneumoniae103
32S aureus1055952,170
E coli4xl03
33S aureus1034080280
34P aeruginosa1054856,120
35P aeruginosa10413851,338
Serratia sdd104
36P aeruginosa10309515,000
P mirabilis100
S epidermidis100
37P aeruginosa19xl0386518
S aureus103
38S aureus10479510,240
39H influenzae108259015,400
Enterobacter spp103
S aureus107
40H influenzae104035236
S epidermidis104
41K pneumoniae105485600
S aureus105
42P aeruginosa1054551,024
43K pneumoniae104309010,910
S aureus104
Candida albicans105
44H alvei5xl077854,290
S aureus5xl03
45S aureus103249510,400
E coli4xl03
46S aureus10420952,120
P vulgaris5xl03
C itrobacter freundii500
47S aureus5xl03070440
P vulgaris104
48S aureus2xl030904,000
B cepacia103
49P aeruginosa5xl04109011,760
50S aureus5xl0622952,176
51E coli1061853,600
S epidermidis100
52S aureus5xl0619903,104
H influenzae5xl06
53S aureus5xl04259811,000
E coli103
54P aeruginosa1075801,020
55S aureus5xl0415907,400
Enterobacter spp103
56Streptococcus B10540959,440


Figure 1. ROC curve for the ICs count.


Figure 2. Comparison of the percentage of ICs between patients with and without YAP (mean and 95% Cl).


Figure 3. Correlation between the percentage of ICs (% of IC) and PSB cultures (log10 cfu/mL) in case of pneumonia.