Journal of Postgraduate Medicine
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ARTICLE
 
 
Year : 1979  |  Volume : 25  |  Issue : 1  |  Page : 15-21  

Pattern of aerobic sputum bacteriology in respiratory tract infections and pneumonias in adults

SR Kamat, GH Tilve, VR Hoskote, Parvin S Anklesaria, UK Sheth 
 Department of Chest Medicine, K.E.M. Hospital and Seth G.S. Medical College, Parel, Bombay 400012, India

Correspondence Address:
S R Kamat
Department of Chest Medicine, K.E.M. Hospital and Seth G.S. Medical College, Parel, Bombay 400012
India

Abstract

A 4 year study on 93 pneumonias, 70 respiratory tract infec­tions and 20 normals for sputum bacteriology is reported. In controls, mainly Streptococcus pyogenes Staphylococcus and Branhamella catarrhalis were seen and frequently duplicated. In patients, there was a predominance of gram negative bacteria, mainly Enterobacter, Pseudomonas, Klebsiella species. There was some change in the individual frequency over these years, probably attributed to changes in the patterns of antibiotic usage in the general community.



How to cite this article:
Kamat S R, Tilve G H, Hoskote V R, Anklesaria PS, Sheth U K. Pattern of aerobic sputum bacteriology in respiratory tract infections and pneumonias in adults.J Postgrad Med 1979;25:15-21


How to cite this URL:
Kamat S R, Tilve G H, Hoskote V R, Anklesaria PS, Sheth U K. Pattern of aerobic sputum bacteriology in respiratory tract infections and pneumonias in adults. J Postgrad Med [serial online] 1979 [cited 2019 Dec 6 ];25:15-21
Available from: http://www.jpgmonline.com/text.asp?1979/25/1/15/42099


Full Text

 Introduction



Since the introduction of antibiotics, the pattern of organisms causing infec­tions has changed. This is well docu­mented by Finland. [3],[4] from data derived from monitoring of cases with bacterae­mia in Boston, U.S.A. His main findings are that the number of admissions with bacteraemia over 30 years from 1935 has increased in adult by 3˝ times. Case fatality rates dropped from 60% in 1935 to 30% in 1947 and rose to 40% in 1961. The mortality was the lowest between 10-29 years of age and then increased steadily. The striking feature in his re­port was a persistent change in patho­genic bacteria which now are gram nega­tive bacilli mainly enteric organisms such as E. coli, Proteus, Pseudomonas and Enterobacter species.

The change in the pattern in respira­tory infections was confirmed by Tillot­son and Lerner, [7] and Sullivan et al. [6] Comparable data has not come from In­dia but Sainani and Fulambarkar [5] have reported Pneumococci in 44%, Strepto­coccus haemolyticus in 10%, Staphy­lococcus in 31% and Klebsiella, H. influ­enzae, E. coli, Pseudomonas in 1 to 3 per cent of pneumonia cases.

In this institute, a prospective survey of cases of lobar pneumonia in adults was done from 1972 to 1974 in 108 cases. For standardising technical methods in 1975, we did duplicate cultures in nor­mals, in cases with acute 'cold' as out­patients and in patients of chronic lung disease admitted for acute exacerbations. The bacteriological aspects will be dis­cussed in this report.

 Material And Methods



From patients admitted to the medical wards with history of fever, respiratory symptoms and radiographic evidence of segmental or lobar consolidation, 108 patients were selected over 3 years. Cases (a) with a suspicion of malignancy (b) with obvious tuberculosis (one case from first series, three & four cases re­spectively from the second & third series were omitted as they were found to have Pulmonary Tuberculosis at a later date). (c) who had received chemo­therapy in previous 3 days, (d) who were pregnant, (e) with age below 12 years and (f) who were moribund were ex­cluded. Two patients died from the first series in 24 hours. One and four cases re­spectively from series first and second were uncooperative and were not included in the series. In each case the sputum sample was collected on admission by a doctor after thorough clearing of the nose and mouth. Then the patient was made to gargle with sterile saline and an expec­torate from the chest was collected. Ex­cept in the first 29 patients, another sam­ple was collected and processed after 48-72 hours.

The control group consisted of 20 nor­mal persons. In addition, 20 persons with acute `cold' and 50 patients of chro­nic lung disease with acute lower respi­ratory exacerbations were also studied [Table 1]. The normals and "acute cold" patients consisted basically of hos­pital employees. The latter had basic diagnosis as chronic bronchitis (16), bronchiectasis (17), bronchial asthma (5), lung abscess (6), and miscellaneous (6).

The sputum sample was plated direct­ly on superimposed blood agar and cho­colate agar plates and incubated at 37°C for 24 hours. A smear was prepared and stained by Gram stain for all samples except in category 3 of [Table 1]. These were classified as Gram positive, nega­tive or mixed organisms. The isolated colonies were inoculated (in nutrient broth and glucose broth for Streptococci). The broth culture was inoculated and further identification was done according to the method of Cowan & Steel. [2] Sensitivity test was done by the method of Bauer et al [1] on a 6 hour broth culture.

 Results



[Table 1] lists the number of cultures studied and the organisms isolated. In controls, the frequency of bacteria per culture seemed higher probably because of Branhamella, catarrhalis.

Bacteriology in control groups

In normals, the predominant organisms were Streptococci, Staphylococci and Branhamella catarrhalis [Table 2].

There were only two isolates of other Gram negative bacteria. In acute `cold' group, while organisms were similar, there were 10 isolates of other Gram negative bacteria (4 Klebsiella).

Thus it appeared that with the pre­sence of infection, a greater frequency of Gram negative bacteria is seen. For control group, our techniques in bacte­rial isolation were reliable; in 31 of 40 subjects (78%) the same bacteria were isolated [Table 3]. In the majority of the control smears showing Gram posi­tive bacteria, we isolated mixed orga­nisms on culture [Table 4]. Of 14 cases from the normal group with mixed cul­ture status, 12 cultures were due to Branhamella catarrhalis. In acute `cold' group, of 13 with mixed culture status, 8 were due to Branhamella catarrhalis.

Results of bacterial drug sesitivity are shown in [Table 5]. In controls, while majority of strains of Steptococcus pyo­ genes were sensitive to penicillin, all were sensitive to streptomycin and chlo­ramphenicol. A third of Streptococcal strains seemed resistant to new antibiotics (ampicillin, cephalexin and gentamycin).

Similar trends were seen for Staphy­lococci but a large proportion were sen­sitive to gentamycin.

The trends for other bacteria were similar but numbers were too small for any reliable conclusion.

Bacteriology in Respiratory Infections

Over 4 years at this hospital, Strepto­coccus pyogenes is becoming increasing­ly frequent [Table 2]. Thus, successive proportional percentages are 16, 2, 17 and 46. Streptococcus pneumoniae seem­ed uncommon, Staphylococci were iso­lated in a small proportion, being most frequent in 1974. Branhamella catar­rhalis, was uncommon in cases with pneumonia but was seen often in acute infective exacerbations, with chronic lung disease.

Over the period, infection with Kleb­siella has become commoner; so also Enterobacter, especially in pneumonia group. Pseudomonas was commoner in chronic lung cases but was not seen in pneumonia cases. In the latter group coliforms were seen oftener.

Duplicate cultures were done in 7 cases of the first series and in all cases of the second and third pneumonia series. Thus out of 64 patients with pneumonia, in 20 (31%) duplicate cultures showed the same organisms.

Of 42 patients with acute infective ex­acerbations, 17 (40%) showed same organisms on second culture.

In 1973, Staphylococci, Klebsiella and Enterobacter were predominant while in 104, they were Streptococci and Enterobacter: in 1975, these were Strep­tococci, Branhamella catarrhalis and Pseudomonas.

[Table 4] reveals the smear culture cor­relation in 93 pneumonia cases.

[Table 5] shows results of drug sensiti­vities in pneumonia cases.

Streptococcus pyogenes: A large pro­portion of Streptococcus pyogenes were resistant to penicillin, sulphadiazine and epicillin; a majority were sensitive to ampicillin, gentamycin and cephalexin while almost all were sensitive to strepto­mycin, tetracycline and chloramphenicol.

Staphylococci: Almost all strains were resistant to penicillin, less often to epi­cillin, sulphadiazine and ampicillin. Most strains were sensitive to streptomycin tetracyline, chloramphenicol and genta­mycin. Most strains of Branhamella catarrbalis, were sensitive to sulphadia­zine, epicillin, streptomycin. tetracycline and chloramphenicol.

Klebsiella: The strains seemed resistant to penicillin, sulphadiazine, ampicillin and epicillin. The best drug seemed to be streptomycin or chloramphenicol.

Enterobacter aerogenes: The strains formed the largest group which did not seem sensitive to pencillin, sulphadia­zine, streptomycin and ampicillin. A few were sensitive to epicillin and cephalexin, while most were suseptible to chloram­phenicol. The miscellaneous Gram nega­tive group showed sensitivity to strepto­mycin then to tetracycline and chlora­mphenicol. The strains were frequently resistant to penicillin, ampicillin, epicil­lin, sulphadiazine and many times to gen­tamycin.

 Discussion



From India we are unaware to such serial data over 4 years on patterns in bacterial isolations from sputum in pneu­monia patients, control group and mis­cellaneous respiratory infections.

These results reveal that bacteria causing respiratory infections in urban community of Bombay have changed. As we have excluded cases which had received chemotherapy in preceding 3 days, this may not be the immediate cause of these changes in flora. But the trends seen over 4 years may have a bearing upon the prevailing practice of antibiotic usage in the community. The work from abroad quoted earlier [3],[4],[6] supports this interpretation. As hospital inpatients are a selected sample, our data can not represent a true status in the community.

It is interesting to note that Strepto­coccus pneumoniae was uncommon in our study. We checked our bacteriologic techniques in a control group and found that normals (Presumably with orophary­ngeal secretions) showed different orga­nisms which were consistently isolated. In pneumonia cases, consistent double isolation was seen in 35 per cent. Over 3 years, there was a changing pattern with a predominance of gram negative bacteria.

Drug sensitivity patterns revealed that majority of strains were surprisingly re­sistant to penicillin, sulphadiazine and ampicillin. As epicillin is related to the latter, resistance to it may be cross link­ed. It is possible that this pattern may be related to over usage of these agents over a prolonged period in urban com­munity.

The newer antibiotics, viz. cephalexin also showed resistance for several strains but emergence of similar phenomenon to streptomycin, tetracycline and chloram­phenicol is not evident. This data may have relevance to a rational approach to drug therapy in our situation. Similar changes in the pattern has been shown by Wysocki and Drunner [8] from Germany. They showed in cultures from wound and urine, that Staphylococci, E. coli, Pseudomonas aeruginosa, Aerobacter and Proteus group formed the major orga­nisms.

 Acknowledgements



We thank Dr. C. K. Deshpande, Dean for allowing us to carry out this work. Kind help given by Prof. K. G. Nair and various residents is appreciated. Dr. H. C. Barbhaiya helped in obtaining drugs and other help.

References

1Bauer, A. W., Kirby, W. M. M. and Sherris, J. C.: Antibiotic susceptibility testing by a standardised single disc method. Amer. J. Clin. Path., 45: 493­496, 1966.
2Cowan, S. T.: "Manual for the Identifica­tion of Medical Bacteria". Editors-Cowan, S. T. and Steel, K. J., 2nd Ed. Cam­bridge University Press, 1974.
3Finland, M.: Changing ecology of bacte­rial infections as related to antibacterial therapy. J. Infect. Dis., 122: 419-431, 1970.
4Finland, M.: Changing Prevalence of pathogenic bacteria in relation to time and the introduction and use of new anti­microbial agents. Bayer symposium III: Bacterial infections. Ed. Finland, M., Marget, W., Barthman, K., Springer­Verlag, New York, 1971, pp. 4-18.
5Sainani, G. S, and Fulambarkar, A. M.: Study of bacterial pneumonias-evaluation of Lung biopsy. J. Ass. Phys. Ind., 23: 503-508. 1975.
6Sullivan, R. J. Jr., Dowdle, W. R., Marina, W. M. and Hierholzer, J. C.: Adult pneumonia in a general hospital: etiology and host risk factors. Arch. Int. Med., 129: 933-942, 1972.
7Tillotson, J. R. and Lerner, A. M.: Pneumonias caused by Gram negative bacilli, Medicine, 45: 65-76, 1966.
8Wysocki, S. and Drunner, H. V.: The changing pattern of infecting organisms. Bayer symposium III: Bacterial infec­tions. Ed. Finland, M., Marget, W., Barthman, K., Springer-Verlag, New York, 1971, pp. 25-29.

 
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