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| Year : 1985 | Volume
: 31
| Issue : 1 | Page : 24-7 |
Shigellosis (antibiotic resistance and transfer of R-factor).
Gaikwad SS, Deodhar LP
How to cite this article:
Gaikwad S S, Deodhar L P. Shigellosis (antibiotic resistance and transfer of R-factor). J Postgrad Med 1985;31:24 |
Dysentery has been one of the major epidemic diseases in the history of mankind and one of the commonest killing diseases in all parts of the world.[4] Shigellae still account for a significant proportion of bacillary dysentery in many tropical and subtropical areas of the world.[12] The ever changing pattern of antimicrobial resistance of Shigella to various antibiotics make it imperative to know the prevalent antibiogram in order to reduce the mortality and morbidity associated with shigellosis. This study was therefore undertaken to determine the incidence, predominant serotype and antibiotic sensitivity pattern of shigellae isolated from patients of a large general hospital in Bombay. Also preliminary genetic studies for transfer of R-factor were performed.
Rectal swab and faeces of the patients studied in the Microbiological laboratory for over a period of 18 months were included in the present study. The specimen was streaked onto blood agar, MacConkey agar, and Salmonella-Shigella agar plates, inoculated into selenite F broth and incubated overnight at 37°C. Selenite F broth was subcultured onto a Salmonella-Shigella plate. Colonies suggestive of shigella, were picked up from blood agar plates while non-lactose fermenting colonies were picked up from MacConkey agar and Salmonella-Shigella agar. The isolates were identified on the basis of their biochemical characteristics,[10] and serotyped by the slide agglutination test using antisera supplied by the Haffkine Biopharmaceutical Corporation Ltd. Antibiotic sensitivity to the routinely used antibiotics was determined by the Bauer-Kirby method, and the minimum inhibitory concentration (MIC) was determined by the agar dilution method.[7]
Clinical history of the patients was noted and strains were sent to National Shigella Centre, Lucknow for confirmation of the identity. Conjugation studies with shigellae donor strains and recepient E. coli K12 F- which had been made resistant to 120 ug/ml of sodium azide (by selection on solid media), were conducted to detect the presence and transfer of R-factor. These conjugation studies were done employing techniques described by Lewis.[6]
Forty-one cases of shigellosis occurred within a span of 18 months; of these, 11 (26.83%) were in adults and 30 (73.17%) in children. In all patients, only Shigella dysenteriae type I (32 cases) and Shigella flexneri (9 cases) were found to be the causative agents. [Table - 1] shows the distribution of the two serotypes of shigellae in the various age groups. The antibiotic sensitivity test results of all the 41 shigella strains from patients is shown in [Table - 2]. The resistance pattern and the mean MIC levels of the above strains of shigellae are shown in [Table - 3]. All strains of shigellae were resistant to atleast one of the routinely used antibiotic and multiple drug resistance was seen in 13 (31.7%) of the cases.
All the R-factors were easily transferred from the donor to the E. coli K 12 and in most cases, the full spectrum was transferred. The transfer of an incomplete spectrum, in some cases, was due to the non-transfer of streptomycin resistance. Only 6 of the 33 streptomycin-resistant strains could transfer resistance to recepient E. coli K 12 F.
Shigellosis is more common in the paediatric age group, particularly in the first 5 years of life. Various other workers[2],[11] also reported similar higher incidence of shigellosis in the first decade of life.
Shigella dysenteriae type 1 was the most predominant organism followed by Shigella flexneri; none of the cases of shigellosis in the present study was found to be caused by Shigella boydii or Shigella sonnei. Pawar et al[9] also reported the predominance of Shigella dysenteriae type 1 and the absence of Shigella boydii or Shigella sonnei isolates in cases of shigellosis studied by them.
The shigellae isolated were usually susceptible to gentamicin, ampicillin and kanamycin, though relatively resistant to chloramphenicol, streptomycin and tetracycline. Arora et al[1] have also shown a similar increase in resistance to various antibiotics. On the other hand, Kaliyugaperumal et al[5] did not report any kanamycin resistant strains while Paniker et al[8] did not report any gentamicin or kanamycin resistant strains. Therefore, it is possible that antibiotic sensitivity of shigellae varies from region to region.
These resistant shigellae carried R-factors which could transfer the full resistance present in the donor to the recipient except for those resistant to streptomycin. In our study, 18.8% of the streptomycin resistant strains could transfer resistance to recipients E. coli K12. Paniker et al[8] consistently failed to transfer streptomycin resistance while Kaliyugaperumal et al[5] only transferred 51.5% of the streptomycin resistance. Streptomycin resistance could be of chromosomal origin, but, further studies, showing inability to transfer resistance, using suitable donor strains in tri-parental crosses are required to draw positive conclusions on the chromosomal origin of streptomycin resistance of these shigella strains.
Indiscriminate use of antibiotics by the clinician, in cases of mild diarrhoea is responsible for the spread of R-factors due to selection pressure. This leads to the emergence of multiple drug resistant shigellae. Therefore, controlled administration of antimicrobial agents based on antibiotic sensitivity reports and their restricted usage only in definitely indicative situations are essential to control the emergence of multiple drug resistant shigella.
| 1. | Arora, D. R., Midha, N. K., Ichhpujani, R. L. and Chugh, T. D.: Drug-resistant shigellosis in North India. Ind J. Med. Res., 76: 74-79, 1982.  |
| 2. | Arya, D., Chitkara, N. L., Agarwal, K. C. and Ganguly, N. K.: Shigellosis in Chandigarh. Ind. J. Pathol. and Microbiol., 20: 15-21, 1977. |
| 3. | Bauer, A. W., Kirby, W. M. M., Sherris, J. C. and Turck. M.: Antibiotic susceptibility testing by a standardized single disc method. Amer. J. Clin. Pathol.. 45: 493-496, 1966. |
| 4. | Forfar, J. O. and Arneil, G. C. "Diseases due to infection." In. "Text Book of Paediatrics." Churchill Livingston, Edinburgh and London, 1973, p. 1291. |
| 5. | Kaliyugaperumal, V., Gupta, U. and Mohapatra, L. D.: Antimicrobial drug resistance and R-factors in shigella. Ind. J. -Med. Res., 68: 220-224. 1978. |
| 6. | Lewis, M. J.: Multiple transmissible drug resistance in an outbreak of shigella flexneri infection. Lancet, 2: 953-956, 1967. |
| 7. | Mastan, J. M.: Antimicrobial susceptibility tests: Laboratory testing in support of antimicrobial therapy, In, "Gradwohl's Clinical Laboratory Methods and Diagnosis." 8th Edition, Editors: A. C. Sonnenwirth and L. Jarrette, The C. V. Mosby and Company, Saint Louis, Toronto and London, 1980, pp. 1937-1970. |
| 8. | Paniker, C, K. J., Vimala, K. N., Bhat, Prema and Stephen, S.: Drug resistant shigellosis in South India. Ind. J. Med. Res., 68: 413-417, 1978. |
| 9. | Pawar, S. G., Pathak, A. A., Junnarkar, A. R. and Bhavthankar, A. G.: Shigellosis in Miraj. In, "Proceedings of the Third All India Annual Congress of Medical Microbiologists" held at T.N. Medical College, Bombay, Maharashtra, November, 1979, pp. 52-59. |
| 10. | Sonnenwirth, A. C.: Collection and culture of specimens and guides for bacterial identification. In, "Gradwohl's Clinical Laboratory Methods and Diagnosis," 8th Edition, Editors: A. C. Sonnenwirth and L. Jarrette, The C. V. Mosby and Company, Saint Louis, Toronto and London, 1980, p, 1607. |
| 11. | Stephen, S., Kaiwar, R., Indrani, R., and Rao, K. N. A.: Shigellosis in South-West coast of India. Ind. J. Pathol. and Microbiol., 21: 233-239, 1978. |
| 12. | Woodruff. A. W.: "Medicine in Tropics." Churchill, Livingston, Edinburgh and London, 1974, p. 249. |
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