934 One patient, aged 41, with corneal pigmentation, who had had normal fundi two years earlier, had speckled pigmentation in the macular area. Another patient, aged 50, without corneal changes, had a clump of fine pigmentations in the macula. The retinal changes remained unchanged after four to six months.


Department of Ophthalmology, University Hospital, 750 14 Uppsala, Sweden.



SIR,—The emergence of bacterial resistance



during therapy has been reported.I-4 MayI describe my own sad experience of a recent episode? Four patients attending the surgical outpatient department with varicose ulcer which on swabbing grew Pseudomonas ceruginosa were treated with topical gentamicin (’Cidomycin’) by a registrar without the knowledge of his consultant. Although all the strains were sensitive initially to gentamicin, they developed resistance after 2-3 weeks of treatment. On inquiry the registrar said that he did not know that gentamicin and cidomycin were the same antibiotic. Details of the isolates are given below:

+ Growth. No growth. *Minimum mhibnory concentration -

by the agar dilution technique.

ample evidence that repeated topical application of antibiotic will promote bacterial resistance ’1 6 whether it is used for prophylaxis or treatment. This disturbing incident emphasises even more strongly that valuable or potentially lifesaving antibiotics should be used only when absolutely necessary-and never topically. Since local antibiotics seldom contribute to the prevention of postoperative wound infections or to the healing of the lesion itself, perhaps it would be wiser to choose an antiseptic instead(though bacteria can resist disinfectants as well.8) Although strains A, B, and C are identical in serological and phage typings, we have failed to incriminate any common source for these infections. After this episode all stock of gentamicin for local use was withdrawn from the outpatient department, and the microbiology laboratory no longer reports sensitivity testing ofgentamicin on swabs taken from ulcers, pressure sores, eyes, ears, or wound infections (unless parenteral therapy is indicated). A committee (consisting of general surgeon, orthopaedic surgeon, physician, pharmacist, senior nursing officer, and microbiologist) has been formed to formulate an antibiotic policy9 in order to minimise misuse of antibiotics in future. There is


I am greatly indebted to the cross infection reference laboratory, Central Public Health Laboratory, Colindale, for typing these strains. Public Health Laboratory, Whipps Cross Hospital, Leytonstone, London E11 1NR. 1. 2.

SIR,-In assessing contradictory results reported with unsaturated fatty acids as suppressors of the immune response, great care must be taken to distinguish between in-vitro and in-vivo experiments. Whilst there is general agreement about the former,’-’ this is not so for the latter. Nothing can usefully be said at this stage of the "blind" human kidney transplantation study still in progress, and we must also await independent confirmation of the positive reportg in multiple sclerosis. In animal transplant experiments, 13 some have had positive results9 10 and others have not." Uldall et al.’s experiments13 were significant at p=0.05 to 025-"a level of significance we are reluctant to accept". On the other hand, Mertin8 cites unpublished work by Hughes et al. in which linoleic acid has been shown to suppress allergic encephalomyelitis in guineapigs. However, administration of gamma-linolenate (more powerful invitro than linoleic acid itself’4) to M.S. patients over some weeks did not diminish the ability of their lymphocytes to respond to thyroid (F,) antigen, in sharp contrast to the in-vitro findings.1 2 6 On the other hand, the sensitivity of the lymphocytes to linoleic acid was reduced-i.e., returned more towards normal. IS Clearly we are dealing here with a complex situation in which in-vitro and invivo responses differ. It must be borne in mind that "polyunsaturated tatty aods are only one of a number of factors which may influence the interaction of sensitised lymphocytes with specific antigen invivo, and ... the final intensity may represent the algebraic sum of enhancing and inhibitory influences".’6 If linoleic acid is effective in vitro as well as in vivo, there ought to be obvious suppression of immunologically induced disease, and gammalinolenate should be more efficient than linoleic acid itself.’4 Only continuing animal experiment of the type reported by Professor Delbarrell and direct clinical trial will establtsh whether the prospects opened by in-vitro experimentation are going to be fulfilled in vivo. Multiple Sclerosis Research Unit, Royal Victoria Infirmary, Queen Victoria Road, Newcastle upon Tyne NE1 4LP.



SIR,-We have compared the diagnostic value of y-fetopro(A.F.P.) assay results obtained by immunodiffusion in agar

tein and

in the serum of children with Of 223sera tested by both techniques, 121 were positive by immunodiffusion and gave an immunological identity with the A.F.P. isolated from fetal sera. With this technique, we detect quantities of A.F.P. above 250 ng/ml. All these positive results were in patients with hepatoma, teratoma, or acute

by radioimmunoassay


1. Mertin, J., Shenton, B. K., Field. E. J. Br. med. J. 1973, ii, 777. 2 Field, E. J., Shenton, B. K., Joyce, G. ibid. 1974, i, 412. 3. Mertin, J., Hughes, D., Shenton, B. K., Dickenson, J P Klin Wschr 1974.

52, 248. 4. Mertin, J., Hughes, D., Stewart-Wynne, E. Lancet, 1974, i, 1005 5 Paty, D. W., Cousin, H. K., McDonald, L. E. ibid. 1975, i, 1197. 6. Jenssen, H. L., Kohler, H., Günther, J., Meyer-Rienecker, H ibid 1974,




Darrell, J. H., Waterworth, P. M. Br. med. J. 1967, ii, 535. Hamilton-Miller, J. M. T., Reynolds, A. V., Brumfitt, W. Lancet, 1974, ii,

527. 3. Seal, D. V., Strangeways, J. E. M. ibid. 1975, i, 48. 4. Barnham, M., Maddocks, A. C., Gaya, H. ibid. 1975, i, 576. 5. Alder, V. G., Gillespie, W. A. ibid. 1967, ii, 1067. 6. Lowbury, E. J. L., Ayliffe, G. A. J. Drug Resistance in Antimicrobial

Therapy. Springfield, Illinois, 1974.

7 Gilmore, O. J. A., Martin, T. D. M. Br. 8. Lancet, 1974, ii, 1054. 9. British Medical Journal, 1975, ii, 582.


J. Surg. 1974, 61,


7. Mertin, J., Hughes, D. Int. Archs Allergy. 1975, 48, 203. 8. Millar, J. H. D., Zilkha, K. J., Langman, M. J. S., Payling-Wright, H, Smith, A. D., Belin, J., Thompson, R. H. S. Br. med. J. 1973, i, 765 9. Mertin, J. Lancet, 1974, ii, 717. 10. Ring, J., Seifert, J., Mertin, J., Brendel, W ibid. 1974, ii, 1331 11. Brok, J., Field, E. J. ibid. 1975, i, 1382. 12. Salaman, J. R., Millar, D. ibid. p 857. 13. Uldall, P. R., Wilkinson, R., McHugh, M. I., Field, E J, Shenton, B R. Baxby, K., Taylor, R. M. R. ibid. 1975, ii, 128. 14. Field, E. J., Shenton, B. K. Acta neurol. scand. 1975, 52, 121, 15. Shenton, B. K., Jenssen, H. L., Kòhler, H, Meyer-Rienecker, H, Field, E J IRCS, Med. Sci. 1975, 3, 503. 16. Field, E. J., Shenton, B. K. Br med. J. 1973, iv, 738 17 Delbarre, F. Lancet, 1975, ii, 720.

Letter: Unsaturated fatty acids and cellular immunity.

934 One patient, aged 41, with corneal pigmentation, who had had normal fundi two years earlier, had speckled pigmentation in the macular area. Anothe...
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