Journal of Chemotherapy
ISSN: 1120-009X (Print) 1973-9478 (Online) Journal homepage: http://www.tandfonline.com/loi/yjoc20
Microbiological Considerations of the Etiological Agents of Lower Respiratory Tract Infections M.B. Pellegrino, A. Privitera, A. Primavera, M. Puntorieri, A. Nicoletti, S. Stefani & G. Nicoletti To cite this article: M.B. Pellegrino, A. Privitera, A. Primavera, M. Puntorieri, A. Nicoletti, S. Stefani & G. Nicoletti (1992) Microbiological Considerations of the Etiological Agents of Lower Respiratory Tract Infections, Journal of Chemotherapy, 4:4, 211-215, DOI: 10.1080/1120009X.1992.11739166 To link to this article: http://dx.doi.org/10.1080/1120009X.1992.11739166
Published online: 15 Jul 2016.
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Date: 10 August 2017, At: 13:44
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Journal of Chemotherapy
Microbiological Considerations of the Etiological Agents of Lower Respiratory Tract Infections M.B. PELLEGRINO . A. PRIVITERA A. PRIMA VERA . M. PUNTORIERI A. NICOLETTI- S. STEFANI- G . NICOLETTI
Summary ------------------------------One hundred eighty-four sputum specimens from the same number of patients with lower respiratory tract infections were examined to determine the bacterial count and the relationship between the microorganisms isolated and the presumptive pathology. The sputa were subdivided into three groups; "high probability", "low probability", and "contaminated sputa", following the criteria of the microscopic readings: sputum with more than 25 white cells and low numbers of squamous epithelial cells represents true lower respiratory tract infections (high probability); those with fewer than 25 white cells represent non-bacterial infections or non-infected sputa (low probability) while sputa with more than 25 squamous cells per field represent contaminated specimens (contaminated sputa). Statistical analysis was carried out to correlate these data. Haemophilus influenzae, Haemophilus parninfluenzae, Streptococcus pneumoniae, and Streptococcus pyogenes showed significant differences in the three groups considered.
Institute of Microbiology, University of Catania, Italy. Corresponding author: Dr. Stefania Stefani, Institute of Microbiology, University of Catania, Via Androne 81, 95 124 Catania, Italy, tel. 095-7159880 .
© Edizioni Riviste Scientifiche . Firenze
Vol. 4 · n. 4 (211-2 15) · 1992
INTRODUCTION
The sputum Gram stain is widely used as a basis for making a rapid etiological diagnosis in bacterial diseases of the lower respiratory tract, and there are a number of reasons why this approach has had so much success. Sputum is usually readily available; this procedure entails no risk to the patient; interpretations require no sophisticated equipment; evaluation can be completed within a few minutes. Sputum assessment is very inexpensive and presumably this test provides invaluable diagnostic and prognostic information 1 • A dispute exists in the literature regarding the ability of clinicians to rely on a Gram stain of sputum to indicate which treatment of community-acquired respiratory tract infections would be suitable; there are studies that support or refute the diagnostic specificity of Gram stain sputum 2 ' 3 • In this brief report we examine sputum smears quantitatively and qualitatively, Gram stained and prepared from clinical specimens, to see how reliable they are and the clinical importance of the isolates. MATERIALS AND METHODS
Study design One hundred eighty-four sputum samples, belonging to the same number of hospitalized patients with community-acquired lower respiratory tract infections (the diagnoses were made based on clinical findings and chest roentgenograms), were examined microscopically as follows : a purulent portion of sputum was carefully ISSN 1! 20-009X
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M.B. PELLEGRINO • A. PRIVITERA • A. PRIMAVERA • M. PUNTORIERI • A. NICOLETTI, et
212
selected and transferred to a clean petri dish. A Gram stained smear was prepared from this portion. Smears were allowed to air dry for 10 min and then heat fixed and Gram stained. The interpretation of the smears was performed to determine the extent of contamination with saliva and, therefore, acceptability of a specimen for bacterial culture and a possible correlation between the bacteria seen in the microscopic reading and the microorganisms isolated. The presence of leukocytes and squamous epithelial cells determined a division of the sputa into different groups. According to Geckler 4 all the sputa with more than 25 leukocytes and 10-25 squamous epithelial cells per field were considered highprobability sputa; those with fewer than 25 white cells were considered low probability sputa. The other sputa with more than 25 squamous epithelial cells per microscopic field were generally unacceptable because of excessive oropharyngeal contamination s. The specimens were liquefied by sonication with a Vibra Cell sonicator (Sanies and Materials Inc, Danbury, Connecticut USA) for 10 sat
an amplitude of 12 J.Lm and diluted 1:2 in normal saline 6 • Cultures were then made from dilutions by streaking one loopful (0.01 ml) onto plates of different media. All the strains were isolated and identified by means of standard procedures 7 • Statistical analysis was performed to determine the level of significance in the three groups considered. Analysis of variance was not performed because, in spite of the transformation with X1 = Vx, we did not observe a homogeneity of variance (Bartlett test). We used an approximative test proposed by Armitage 9 with the use of Wt quantity, the inverse of estimated variance of Yi and of the formula: G =w1yf - (wlyi) 2/wl In the null hypothesis it is distributed approximately as a chi-square test. RESULTS
Table 1 shows the correlation between the major groups of microorganisms,
etiologic
TABLE 1 - Correlation between microscopic readings and isolated (497 observations).
Microorganisms
High probability (n. 232) Yes
%
Low probability (n. 197)
Contaminated (n . 68)
No
Yes
43 (67 .2)
21
7 (7.7)
2
22 (73 .3)
8
8
2
No
Yes
15
%
%
No
Gram-negative pleomorphic bacilli
64 (8 1)
Gram-negative bacilli
28 (84 .8)
5
51 (89.4)
6
44 (91.6)
4
19 (82.6)
4
15 (65 .2)
8
17 (70 .8)
7
6 (66.6)
3
14 (38 .8)
22
17 (56.6)
13
8 (47 .0)
9
0 (0)
0
48 (70. 5)
20
Streptococci *
Staphylococci
*
Gram-negative diplococci
Fungi
0 (0)
4
0 (0)
Total
172 (74 .1)
60
143 (72.5)
(80)
54
* Staphylococci are often indistinguish ible from the other Gram- positive cocci (Streptococci).
213
MICROBIOLOGICAL CONSIDERATIONS OF THE ETIOLOGICAL AGENTS OF LOWER RESPIRATORY, ETC.
TABLE
2 - Quantitative evaluation of the 184 sputa examined.
Bacterial count (CFU/m])
1-9.9x10 1 1-9.9x 10 2 1-9.9x10' 1-9.9x 10' 1-9.9x 10' 1-9.9x 10 6
Highprobability (n . 84)
LowContaminated probability (n . 29) (n·. 71)
0 0 0 24 33 27
0 0 0 20 28 23
2 0 13 14 0 0
84 9.4x10' 1.15x10' 1.25x10'
71 8.7x10' l.ll x10 6 1.32x10'
29 1.9x10' 1.8x10' 3.3x10'
Statistical analys is
Downloaded by [Australian Catholic University] at 13:44 10 August 2017
Sample size
x
sd se
G for degrees freedom = 199 .091
P
ISSN: 1120-009X (Print) 1973-9478 (Online) Journal homepage: http://www.tandfonline.com/loi/yjoc20
Microbiological Considerations of the Etiological Agents of Lower Respiratory Tract Infections M.B. Pellegrino, A. Privitera, A. Primavera, M. Puntorieri, A. Nicoletti, S. Stefani & G. Nicoletti To cite this article: M.B. Pellegrino, A. Privitera, A. Primavera, M. Puntorieri, A. Nicoletti, S. Stefani & G. Nicoletti (1992) Microbiological Considerations of the Etiological Agents of Lower Respiratory Tract Infections, Journal of Chemotherapy, 4:4, 211-215, DOI: 10.1080/1120009X.1992.11739166 To link to this article: http://dx.doi.org/10.1080/1120009X.1992.11739166
Published online: 15 Jul 2016.
Submit your article to this journal
View related articles
Citing articles: 4 View citing articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=yjoc20 Download by: [Australian Catholic University]
Date: 10 August 2017, At: 13:44
Downloaded by [Australian Catholic University] at 13:44 10 August 2017
Journal of Chemotherapy
Microbiological Considerations of the Etiological Agents of Lower Respiratory Tract Infections M.B. PELLEGRINO . A. PRIVITERA A. PRIMA VERA . M. PUNTORIERI A. NICOLETTI- S. STEFANI- G . NICOLETTI
Summary ------------------------------One hundred eighty-four sputum specimens from the same number of patients with lower respiratory tract infections were examined to determine the bacterial count and the relationship between the microorganisms isolated and the presumptive pathology. The sputa were subdivided into three groups; "high probability", "low probability", and "contaminated sputa", following the criteria of the microscopic readings: sputum with more than 25 white cells and low numbers of squamous epithelial cells represents true lower respiratory tract infections (high probability); those with fewer than 25 white cells represent non-bacterial infections or non-infected sputa (low probability) while sputa with more than 25 squamous cells per field represent contaminated specimens (contaminated sputa). Statistical analysis was carried out to correlate these data. Haemophilus influenzae, Haemophilus parninfluenzae, Streptococcus pneumoniae, and Streptococcus pyogenes showed significant differences in the three groups considered.
Institute of Microbiology, University of Catania, Italy. Corresponding author: Dr. Stefania Stefani, Institute of Microbiology, University of Catania, Via Androne 81, 95 124 Catania, Italy, tel. 095-7159880 .
© Edizioni Riviste Scientifiche . Firenze
Vol. 4 · n. 4 (211-2 15) · 1992
INTRODUCTION
The sputum Gram stain is widely used as a basis for making a rapid etiological diagnosis in bacterial diseases of the lower respiratory tract, and there are a number of reasons why this approach has had so much success. Sputum is usually readily available; this procedure entails no risk to the patient; interpretations require no sophisticated equipment; evaluation can be completed within a few minutes. Sputum assessment is very inexpensive and presumably this test provides invaluable diagnostic and prognostic information 1 • A dispute exists in the literature regarding the ability of clinicians to rely on a Gram stain of sputum to indicate which treatment of community-acquired respiratory tract infections would be suitable; there are studies that support or refute the diagnostic specificity of Gram stain sputum 2 ' 3 • In this brief report we examine sputum smears quantitatively and qualitatively, Gram stained and prepared from clinical specimens, to see how reliable they are and the clinical importance of the isolates. MATERIALS AND METHODS
Study design One hundred eighty-four sputum samples, belonging to the same number of hospitalized patients with community-acquired lower respiratory tract infections (the diagnoses were made based on clinical findings and chest roentgenograms), were examined microscopically as follows : a purulent portion of sputum was carefully ISSN 1! 20-009X
Downloaded by [Australian Catholic University] at 13:44 10 August 2017
alii
M.B. PELLEGRINO • A. PRIVITERA • A. PRIMAVERA • M. PUNTORIERI • A. NICOLETTI, et
212
selected and transferred to a clean petri dish. A Gram stained smear was prepared from this portion. Smears were allowed to air dry for 10 min and then heat fixed and Gram stained. The interpretation of the smears was performed to determine the extent of contamination with saliva and, therefore, acceptability of a specimen for bacterial culture and a possible correlation between the bacteria seen in the microscopic reading and the microorganisms isolated. The presence of leukocytes and squamous epithelial cells determined a division of the sputa into different groups. According to Geckler 4 all the sputa with more than 25 leukocytes and 10-25 squamous epithelial cells per field were considered highprobability sputa; those with fewer than 25 white cells were considered low probability sputa. The other sputa with more than 25 squamous epithelial cells per microscopic field were generally unacceptable because of excessive oropharyngeal contamination s. The specimens were liquefied by sonication with a Vibra Cell sonicator (Sanies and Materials Inc, Danbury, Connecticut USA) for 10 sat
an amplitude of 12 J.Lm and diluted 1:2 in normal saline 6 • Cultures were then made from dilutions by streaking one loopful (0.01 ml) onto plates of different media. All the strains were isolated and identified by means of standard procedures 7 • Statistical analysis was performed to determine the level of significance in the three groups considered. Analysis of variance was not performed because, in spite of the transformation with X1 = Vx, we did not observe a homogeneity of variance (Bartlett test). We used an approximative test proposed by Armitage 9 with the use of Wt quantity, the inverse of estimated variance of Yi and of the formula: G =w1yf - (wlyi) 2/wl In the null hypothesis it is distributed approximately as a chi-square test. RESULTS
Table 1 shows the correlation between the major groups of microorganisms,
etiologic
TABLE 1 - Correlation between microscopic readings and isolated (497 observations).
Microorganisms
High probability (n. 232) Yes
%
Low probability (n. 197)
Contaminated (n . 68)
No
Yes
43 (67 .2)
21
7 (7.7)
2
22 (73 .3)
8
8
2
No
Yes
15
%
%
No
Gram-negative pleomorphic bacilli
64 (8 1)
Gram-negative bacilli
28 (84 .8)
5
51 (89.4)
6
44 (91.6)
4
19 (82.6)
4
15 (65 .2)
8
17 (70 .8)
7
6 (66.6)
3
14 (38 .8)
22
17 (56.6)
13
8 (47 .0)
9
0 (0)
0
48 (70. 5)
20
Streptococci *
Staphylococci
*
Gram-negative diplococci
Fungi
0 (0)
4
0 (0)
Total
172 (74 .1)
60
143 (72.5)
(80)
54
* Staphylococci are often indistinguish ible from the other Gram- positive cocci (Streptococci).
213
MICROBIOLOGICAL CONSIDERATIONS OF THE ETIOLOGICAL AGENTS OF LOWER RESPIRATORY, ETC.
TABLE
2 - Quantitative evaluation of the 184 sputa examined.
Bacterial count (CFU/m])
1-9.9x10 1 1-9.9x 10 2 1-9.9x10' 1-9.9x 10' 1-9.9x 10' 1-9.9x 10 6
Highprobability (n . 84)
LowContaminated probability (n . 29) (n·. 71)
0 0 0 24 33 27
0 0 0 20 28 23
2 0 13 14 0 0
84 9.4x10' 1.15x10' 1.25x10'
71 8.7x10' l.ll x10 6 1.32x10'
29 1.9x10' 1.8x10' 3.3x10'
Statistical analys is
Downloaded by [Australian Catholic University] at 13:44 10 August 2017
Sample size
x
sd se
G for degrees freedom = 199 .091
P
