Background
Methods
Study population
Definitions
Data and sample collection
Total cell count and cell lysis efficiency analysis
Microbiological evaluation using cultivation methods
The bacterial floral analysis of 16S ribosomal RNA gene
Statistical analysis
Results
Patient characteristics
Variables | Presence of risk | Absence of risk | p value |
---|---|---|---|
factors for aspiration | factors for aspiration | ||
(n=83) | (n=94) | ||
Age, years, mean±SD | 76.6 (9.5) | 64.5 (19.4) | <0.001 |
Gender, male; n (%) | 58 (69.9) | 48 (51.1) | 0.011 |
HCAP; n (%) | 59 (71.1) | 35 (37.2) | <0.001 |
Hospitalization for >2 days in the preceding 90 days | 34 (41.0) | 27 (28.7) | 0.087 |
Residence in a nursing home or extended care facility | 29 (34.9) | 5 (5.3) | <0.001 |
Home infusion therapy (including antibiotics) | 10 (12.0) | 8 (8.5) | 0.437 |
Chronic dialysis during the preceding 30 days | 0 (0.0) | 1 (1.1) | 0.346 |
Home wound care | 0 (0.0) | 0 (0.0) | |
BMI, mean±SDa | 19.6 (4.8) | 20.7 (4.5) | 0.038 |
ECOG PS, median (IQR) | 2 (0.5–3.5) | 1 (0.5–1.5) | <0.001 |
0–1; n (%) | 28 (33.7) | 73 (77.7) | <0.001 |
2; n (%) | 22 (26.5) | 12 (12.8) | |
3–4; n (%) | 33 (39.8) | 9 (9.6) | <0.001 |
Smoking; n, (%)b | |||
Smoker | 7 (10.0) | 9 (10.7) | |
Ex-smoker | 30 (42.9) | 30 (35.7) | |
Non smoker | 33 (47.1) | 45 (53.6) | |
B.Ic | 493.7 (606.1) | 449.4 (641.7) | 0.454 |
Comorbidity; n, (%) | |||
Chronic respiratory disease | 22 (26.5) | 38 (40.4) | 0.051 |
COPD | 11 (13.3) | 23 (24.5) | 0.059 |
Bronchiectasis | 6 (7.2) | 12 (12.8) | 0.224 |
Lung cancer | 7 (8.4) | 3 (3.2) | 0.132 |
Interstitial pneumonia | 6 (7.2) | 9 (9.6) | 0.576 |
Cerebrovascular disease | 30 (36.1) | 0 (0.0) | – |
Neuromuscular diseases | 19 (22.9) | 0 (0.0) | – |
Dementia | 26 (31.3) | 0 (0.0) | – |
Pharyngeal disorder | 7 (8.4) | 0 (0.0) | – |
Gastroesophageal disorder | 27 (32.5) | 0 (0.0) | – |
Diabetes mellitus | 11 (13.3) | 22 (23.4) | 0.084 |
Malignancy excluding lung cancer | 26 (31.3) | 18 (19.1) | 0.060 |
Congestive heart failure | 8 (9.6) | 8 (8.5) | 0.794 |
Chronic kidney disease | 2 (2.4) | 5 (5.3) | 0.450 |
Chronic liver disease | 6 (7.2) | 2 (2.1) | 0.103 |
RA or Sjogren’s syndrome | 0 (0.0) | 9 (9.6) | 0.004 |
Collagen disease | 5 (6.0) | 7 (7.4) | 0.707 |
Psychiatric disease | 2 (2.4) | 4 (4.3) | 0.686 |
Medications; n (%) | |||
Sleeping medications | 17 (20.5) | 10 (10.6) | 0.07 |
Glucocorticoids (PSL>5 mg/day) | 11 (13.3) | 7 (7.4) | 0.202 |
Immunosuppressive agent | 3 (3.6) | 8 (9.5) | 0.178 |
Antipsychotic drugs | 7 (8.4) | 1 (1.1) | 0.027 |
Antidepressant | 3 (3.6) | 6 (6.4) | 0.504 |
History of pneumonia within the previous 1 year; n (%) | 24 (28.9) | 15 (16.0) | 0.038 |
Respiratory failure; n, (%) | 31 (37.3) | 30 (31.9) | 0.448 |
Clinical parameters; n, (%) | |||
Orientation disturbance (confusion) | 21 (25.3) | 8 (8.5) | 0.003 |
Systolic BP<90 mmHg or diastolic BP<60 mmHg | 5 (6.0) | 2 (2.1) | 0.255 |
Body temperature<35 °C or >40 °C | 4 (4.8) | 1 (1.1) | 0.188 |
Pulse rate>125 beats/min | 5 (6.0) | 10 (10.6) | 0.271 |
Laboratory findings | |||
BUN>10.7 mmol/L | 28 (33.7) | 24 (25.5) | 0.232 |
Glucose>13.9 mmol/L | 3 (3.6) | 7 (7.4) | 0.339 |
Hematocrit<30 % | 16 (19.3) | 6 (6.4) | 0.010 |
Albumin, g/dl mean ± SDd | 3.05 (0.61) | 3.29 (0.57) | 0.011 |
Radiographic findings; n, (%)e | |||
Bilateral lung involvement | 54 (65.1) | 50 (53.8) | 0.128 |
Upper lobe dominant opacity | 14 (16.9) | 20 (21.5) | 0.437 |
Lower lobe opacity | 54 (65.1) | 52 (55.9) | 0.216 |
anterior dominant opacity | 8 (9.6) | 14 (15.1) | 0.278 |
posterior dominant opacity | 67 (80.7) | 58 (62.4) | 0.007 |
Gravity-dependent opacity | 67 (80.7) | 67 (72.0) | 0.178 |
Thickening of bronchovascular bundles | 37 (44.6) | 50 (53.8) | 0.224 |
Pleural effusion | 12 (14.5) | 19 (20.3) | 0.299 |
PSI score; mean±SD | 112.0 (40.3) | 81.0 (46.3) | <0.001 |
I-III | 25 (30.1) | 57 (60.6) | |
VI-V | 53 (69.9) | 37 (39.4) | <0.001 |
In hospital mortality | 6 (7.2) | 6 (6.4) | 0.823 |
Total bacterial cell numbers and cell lysis efficiency analysis
The comparison of conventional cultivation methods and the bacterial floral analysis of 16S ribosomal RNA gene
Total | Presence of risk factors for aspiration | Absence of risk factors for aspiration | |||||||
---|---|---|---|---|---|---|---|---|---|
Clone Library Method | Culture | Clone Library Method | Culture | Clone Library Method | Culture | ||||
The predominant phylotypes in BALF | BALF | Sputum | The predominant phylotypes in BALF | BALF | Sputum | The predominant phylotypes in BALF | BALF | Sputum | |
Gram-positive pathogens | |||||||||
Streptococcus pneumoniae | 23 (12.8) | 21 (11.7) | 12 (13.0) | 10 (11.9) | 7 (8.0) | 5 (12.0) | 13 (13.7) | 14 (15.2) | 7 (13.7) |
Streptococcus spp. | 40 (22.3) | 9 (5.0) | 6 (6.5) | 26 (31.0) | 4 (4.5) | 2 (4.8) | 14 (14.7) | 5 (5.4) | 4 (7.8) |
Streptococcus anginosus group | 5 (2.8) | 1 (0.6) | 0 (0.0) | 5 (6.0) | 1 (1.1) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) |
Other Streptococcus spp. | 35 (19.6) | 8 (4.4) | 6 (6.5) | 21 (25.0) | 3 (3.4) | 2 (4.8) | 14 (14.7) | 5 (5.4) | 4 (7.8) |
Staphylococcus aureus | 8 (4.5) | 21 (11.7) | 15 (16.1) | 4 (4.8) | 11 (12.5) | 8 (19.0) | 4 (4.2) | 10 (10.9) | 7 (13.7) |
Methicillin-susceptible S. aureus | – | 7 (3.9) | 4 (4.3) | – | 5 (5.7) | 1 (2.4) | – | 2 (2.2) | 3 (5.9) |
Methicillin-resistant S. aureus | – | 14 (7.8) | 11 (11.8) | – | 6 (6.8) | 7 (16.7) | – | 8 (8.7) | 4 (7.8) |
Staphylococcus spp. (except S. aureus) | 2 (1.1) | 2 (1.1) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 2 (2.1) | 2 (2.2) | 0 (0.0) |
Corynebacterium spp. | 6 (3.4) | 2 (1.1) | 1 (1.1) | 5 (6.0) | 1 (1.1) | 1 (2.4) | 1 (1.1) | 1 (1.1) | 0 (0.0) |
Gemella spp. | 2 (1.1) | 0 (0.0) | 0 (0.0) | 2 (2.4) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) |
Lactobacillus spp. | 1 (0.6) | 0 (0.0) | 0 (0.0) | 1 (1.2) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) |
Rothia spp. | 1 (0.6) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 1 (1.1) | 0 (0.0) | 0 (0.0) |
Gram-negative pathogens | |||||||||
Haemophilus spp. | 28 (15.6) | 23 (12.8) | 10 (10.8) | 14 (16.7) | 8 (9.1) | 5 (12.0) | 14 (14.7) | 15 (16.3) | 5 (9.8) |
Pseudomonas aeruginosa | 10 (5.6) | 18 (10.0) | 9 (9.7) | 2 (2.4) | 8 (9.1) | 3 (7.1) | 8 (8.4) | 10 (10.9) | 6 (11.8) |
Pseudomonas spp. (except P. aeruginosa) | 0 (0.0) | 2 (1.1) | 1 (1.1) | 0 (0.0) | 1 (1.1) | 0 (0.0) | 0 (0.0) | 1 (1.1) | 1 (2.0) |
Moraxella spp. | 8 (4.5) | 7 (3.9) | 4 (4.3) | 5 (6.0) | 5 (5.7) | 1 (2.4) | 3 (3.2) | 2 (2.2) | 3 (5.9) |
Neisseria spp. | 5 (2.8) | 0 (0.0) | 0 (0.0) | 1 (1.2) | 0 (0.0) | 0 (0.0) | 4 (4.2) | 0 (0.0) | 0 (0.0) |
Klebsiella spp | 4 (2.2) | 12 (6.7) | 6 (6.5) | 3 (3.6) | 10 (11.4) | 6 (14.3) | 1 (1.1) | 2 (2.2) | 0 (0.0) |
Escherichia coli | 2 (1.1) | 5 (2.8) | 2 (2.2) | 2 (2.4) | 5 (5.7) | 2 (4.8) | 0 (0.0) | 0 (0.0) | 0 (0.0) |
Enterobacter spp. | 1 (0.6) | 2 (1.1) | 2 (2.2) | 1 (1.2) | 2 (2.3) | 1 (2.4) | 0 (0.0) | 0 (0.0) | 1 (2.0) |
Acinetobacter spp. | 0 (0.0) | 2 (1.1) | 0 (0.0) | 0 (0.0) | 1 (1.1) | 0 (0.0) | 0 (0.0) | 1 (1.1) | 0 (0.0) |
Citrobacter spp. | 0 (0.0) | 1 (0.6) | 1 (1.1) | 0 (0.0) | 1 (1.1) | 1 (2.4) | 0 (0.0) | 0 (0.0) | 0 (0.0) |
Serratia spp. | 0 (0.0) | 2 (1.1) | 0 (0.0) | 0 (0.0) | 2 (2.3) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) |
Burkholderia spp. | 0 (0.0) | 1 (0.6) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 1 (1.1) | 0 (0.0) |
Proteus spp. | 0 (0.0) | 1 (0.6) | 0 (0.0) | 0 (0.0) | 1 (1.1) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) |
Pasteurella spp. | 0 (0.0) | 1 (0.6) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 1 (1.1) | 0 (0.0) |
Anaerobic pathogens | 22 (12.3) | 8 (4.4) | 0 (0.0) | 5 (6.0) | 5 (5.7) | 0 (0.0) | 17 (17.9) | 3 (3.3) | 0 (0.0) |
Prevotella spp. | 11 (6.1) | 3 (1.7) | 0 (0.0) | 4 (4.8) | 2 (2.3) | 0 (0.0) | 7 (7.4) | 1 (1.1) | 0 (0.0) |
Fusobacterium spp. | 5 (2.8) | 1 (0.6) | 0 (0.0) | 1 (1.2) | 0 (0.0) | 0 (0.0) | 4 (4.2) | 1 (1.1) | 0 (0.0) |
Micromonas spp. | 2 (1.1) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 2 (2.1) | 0 (0.0) | 0 (0.0) |
Propionibacterium spp. | 2 (1.1) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 2 (2.1) | 0 (0.0) | 0 (0.0) |
Veillonella spp. | 1 (0.6) | 2 (1.1) | 0 (0.0) | 0 (0.0) | 2 (2.3) | 0 (0.0) | 1 (1.1) | 0 (0.0) | 0 (0.0) |
Porphyromonas spp | 1 (0.6) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 1 (1.1) | 0 (0.0) | 0 (0.0) |
Peptostreptococcus spp. | 0 (0.0) | 1 (0.6) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 1 (1.1) | 0 (0.0) |
Clostridium spp. | 0 (0.0) | 1 (0.6) | 0 (0.0) | 0 (0.0) | 1 (1.1) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) |
Atypical pathogens | |||||||||
Mycoplasma pneumoniae | 14 (7.8) | – | – | 2 (2.4) | – | – | 12 (12.6) | – | – |
Legionella pneumonia | 1 (0.6) | – | – | 1 (1.2) | – | – | 0 (0.0) | – | – |
Actinomyces spp. | 0 (0.0) | 2 (1.1) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 2 (2.2) | 0 (0.0) |
Nocardia spp. | 1 (0.6) | 1 (0.6) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 1 (1.1) | 1 (1.1) | 0 (0.0) |
Oral bacteria | – | 37 (20.9) | 24 (25.8) | – | 16 (18.2) | 7 (16.7) | – | 21 (22.8) | 17 (33.3) |
No growth | – | 32 (18.1) | 4 (4.7) | – | 15 (18.1) | 1 (2.8) | – | 17 (18.1) | 3 (6.0) |
Not analysed | – | – | 91 (51.4) | – | – | 47 (56.6) | – | – | 44 (46.8) |
Total isolates | 179a | 180 | 93 | 84b | 88 | 42 | 95c | 92 | 51 |
Comparison of the results of the bacterial floral analysis of 16S ribosomal RNA gene between patients with or without aspiration risks
Results of simple and multiple linear regression analyses for detecting oral streptococci
b | SE (b) | β | p-value | |
---|---|---|---|---|
Age >80 | 13.92 | 4.47 | 0.229 | 0.002 |
BMI<20 | −4.07 | 2.89 | −0.106 | 0.161 |
Hospitalization for >2 days in the preceding 90 day; n (%) | 4.15 | 4.63 | 0.068 | 0.371 |
Residence in a nursing home or long-term care facility | 14.48 | 5.49 | 0.196 | 0.009 |
Home infusion therapy (including antibiotics) | 9.88 | 7.26 | 0.102 | 0.170 |
ECOG PS of premorbid condition>3 | 23.37 | 4.87 | 0.341 | <0.001 |
COPD | −0.28 | 5.60 | −0.004 | 0.960 |
Interstitial pneumonia | 0.18 | 7.92 | 0.002 | 0.982 |
Lung cancer | −0.16 | 9.55 | −0.001 | 0.987 |
Bronchiectasis | −6.63 | 7.28 | −0.069 | 0.364 |
Cerebrovascular disease | 7.75 | 5.85 | 0.100 | 0.187 |
Neuromuscular diseases | 8.62 | 7.09 | 0.092 | 0.226 |
Dementia | 8.14 | 6.20 | 0.099 | 0.191 |
Gastroesophageal disorder | 5.72 | 6.12 | 0.705 | 0.351 |
Pharyngeal disorder | 19.48 | 11.22 | 0.130 | 0.084 |
Presence of the risk factor for aspiration | 12.78 | 4.31 | 0.219 | 0.004 |
Malignancy excluding lung cancer | −1.73 | 5.10 | −0.026 | 0.735 |
Psychiatric disease | 1.68 | 12.18 | 0.010 | 0.891 |
Sleeping medications | 10.24 | 6.08 | 0.126 | 0.094 |
Antipsychotic drugs | −4.94 | 10.61 | −0.035 | 0.642 |
Antidepressant | 10.40 | 10.01 | 0.078 | 0.300 |
History of pneumonia within the previous 1 year | 16.12 | 4.92 | 0.241 | 0.001 |
Albumin<4 g/dl | −3.25 | 6.56 | −0.037 | 0.621 |
Bilateral lung involvement | 0.01 | 4.37 | 0.0002 | 0.998 |
Lower lobe opacity | −4.67 | 4.40 | −0.08 | 0.291 |
Posterior dominant opacity | 4.56 | 4.87 | 0.071 | 0.351 |
Gravity-dependent opacity | −7.52 | 5.27 | −0.107 | 0.155 |
b | SE (b) | β | p-value | |
---|---|---|---|---|
Age>80 | 6.61 | 4.62 | 0.109 | 0.154 |
Residence in a nursing home or long-term care facility | −3.28 | 6.4 | −0.044 | 0.609 |
ECOG PS of premorbid condition>3 | 17.52 | 5.96 | 0.256 | <0.001 |
Presence of the risk factor for aspiration | 5.69 | 4.54 | 0.097 | 0.211 |
History of pneumonia within the previous 1 year | 10.36 | 4.88 | 0.155 | 0.035 |