Pseudomonas pyocyanea INFECTION TREATED WITH COLISTIN METHANE SULPHONATE

737

this probably accounts for the low blood-sugar value at 2 hours (fig. 3). Diazoxide, added to pure crystalline bovine insulin in a concentration of 0-025 mg. and 0-075 mg. per ml. incubate, did not affect the assay. Discussion One cannot predict from two cases in what proportion of a larger series of patients, treated with diazoxide, diabetes would develop, but trials of the drug should be undertaken only with great caution. There is already evidence that chlorothiazide may aggravate existing diabetes, and occasionally it may even precipitate diabetes in healthy people (Shapiro et al. 1961); and therefore it did not seem ominous that diazoxide should also worsen the control of diabetics (Hutcheon and Barthalmus 1962), for the structure of the two substances is similar. But the acute development of severe symptomatic diabetes is a much more serious toxic action, and it is disturbing that chronic toxicity tests in rats and dogs did not reveal this effect. One possibility is that the combination of diazoxide with a diuretic thiazide may have a much more powerful diabetogenic action than either alone. This could indicate the need for chronic toxicity testing of drug combinations as well as the individual substances. The results of the insulin assay suggest that diazoxide produces diabetes by a direct inhibitory action on the pancreatic islet cells. Thus there is diminished secretion of typical insulin, and consequently less atypical insulin will be formed by the liver (Samaan et al. 1962b). The lack of ketosis and the sensitivity to injected soluble insulin are consistent with this interpretation. The chemical basis of the inhibition of the secretion of insulin is unknown, but fortunately it appears to be completely reversible. The effect of diazoxide in man seems to be similar to that of alloxan (Lukens 1948), though without the nephrotoxic action of alloxan. For this reason it might be worth testing the combination of diazoxide and hydrochlorothiazide as a means of inducing experimental diabetes in animals. A compound with such a serious toxic action is unlikely to have any place in the therapy of hypertension. Other unexplained toxic effects of diazoxide include oedema formation and tachycardia. It may be unwise to draw conclusions about the pharmacological basis of the antihypertensive action of the diuretic thiazides from studies with diazoxide.

Summary Two patients with mild hypertension were treated with a combination of hydrochlorothiazide and a new nondiuretic thiazide, diazoxide. The patients showed a satisfactory fall of blood-pressure on this regime, but unfortunately diabetes mellitus developed in both during their 4th week of treatment. Recovery was prompt after the withdrawal of the drug. Plasma-insulin studies in one of the patients showed that the insulin-like activity was low, and this suggests that the diabetes was caused by a direct inhibitory action on the islet cells of Langerhans. We thank Prof. J. McMichael, F.R.S., and Prof. Russell Fraser for their mterest and support. We are grateful to Dr. J. V. Deakin, of Allen & Hanburys Ltd., for supplies of diazoxide and for much useful information about it. REFERENCES

Hutcheon, D. E., Barthalmus, K. (1962) Brit. med. J. ii, 159. Lauwers, P., Conway, J. (1960) J. Lab. clin. Med. 56, 401. Lukens, F. D. W. (1948) Physiol. Rev. 28, 304. Rubm, A. A., Roth, F. E., Winbury, M. M., Topliss, J. G., Sherlock, M. H., Sperber, N., Black, J. (1961) Science, 133, 2067. Samaan, N. A., Dempster, J., Fraser, R., Please, N. W., Stillman, D. (1962a) J. Endocrin. 24, 263. Stillman, D. (1962b) Biochem. J. 82, 29p. Shapiro, A. P., Benedek, T. G., Small, J. L. (1961) New Engl. J. Med. 265, — —

1028.

Pseudomonas pyocyanea INFECTION TREATED WITH COLISTIN METHANE SULPHONATE MARY MCMILLAN M.D., Ph.D., B. Pharm. Leeds

M.D. Lond., M.R.C.P.

CONSULTANT PATHOLOGIST

CONSULTANT PHYSICIAN

LEWISHAM

HOSPITAL, LONDON, S.E.13

D. M. MACLAREN M.B. Lond. JUNIOR

T. M. L. PRICE

G. W. SCOTT Lond., M.R.C.P.

M.D.

LECTURER IN BACTERIOLOGY

CLINICAL TUTOR IN MEDICINE

GUY’S HOSPITAL, LONDON,

S.E. 1

COLISTIN was isolated by Koyama in 1950 from culture filtrates of Bacillus colistinus, a microorganism obtained from the soil. This antibiotic has been shown to be effective against many gram-negative organisms, including Pseudomonas pyocyanea but not the Proteus group, both in vitro (Forni and Guidetti 1956, Petersdorf and Hook 1960, Schwartz et al. 1959-60, Yow et al. 1961) and in clinical trials in other countries (Petersdorf and Hook 1960, Carroll and Malette 1961, Derot et al. 1961, Traegar et al. 1961, Yow et al. 1961). Severe toxic effects have not occurred with therapeutic dosage or in animal experiments (Chabbert 1958, Schwartz et al. 1959-60, Wright and Welch 1959-60). In a few cases parassthesiae around the face and a maculopapular rash have been reported, but these cleared rapidly on stopping the drug. Colistin, though closely related to polymyxin B, is not identical with it (Cuthbert 1962), and the exact chemical relation between colistin and the polymyxins is not fully understood. Colistin is very poorly absorbed by mouth, and to maintain adequate systemic levels it must be given parenterally as colistin methane sulphonate, 1 mg. of which is equivalent to 12,500 units. Ps. pyocyanea is resistant to most available antibiotics, and there is evidence that infections with it are becoming more common, particularly in debilitated patients (Finland et al. 1959, Barber 1961, Lancet 1962). Pseudomonas septicaemia is usually fatal (Forkner et al. 1958, Curtin et al. 1961, Rabin et al. 1961). Our present study is concerned with infections caused by this organism. Patients and Methods Cases showing clinical and bacteriological evidence of Ps. pyocyanea infection were treated with colistin, even if other organisms were present. Some patients had severe underlying disease, and some were severely debilitated or even moribund. In the majority of cases the organism was isolated in three separate cultures before treatment was started. Where possible, negative cultures were obtained on three consecutive days before the organism was considered to be eradicated. Ps. pyocyanea was identified by its cultural characteristics, sugar reactions, and pigment formation. Preliminary sensitivity tests were carried out using either the disc or the tube technique. Patients were given colistin methane sulphonate (’Colomycin’, subsequently this will be referred to as colistin), 1-5 mega units (120 mg.) intramuscularly at 8-hourly intervals. In one patient with meningitis the initial dose was 3 mega units 8-hourly, and in some of the others the dose was later increased to this level. At least 6 days’ treatment was given in most cases, and it was continued longer if necessary. Topical applications of 0-5 mega unit in 20 ml. of normal saline were also used where indicated. Clinical Results

Forty patients were treated, and they are listed according the sites of infection. Two patients, both with disseminated sclerosis, had infections of bedsores as well as of the urinary tract; they are therefore included under to

738

both these headings. One case of urinary infection cannot be assessed because treatment had to be stopped after a few injections owing to side-effects. Thus, in all, forty-one examples are listed:

Urinary-tract infections (eighteen cases).-Seven

were

associated with severe neurological disorder, and four others had gross structural damage. Despite this, Ps. pyocyanea infection was eradicated in all cases; but, as might be expected, other pathogenic organisms resistant to colistin commonly took its place. The pseudomonas infection recurred in one patient after 15 days, and it was found in another when tested 2 months

later. Skin infections (eight cases).-These included five cases of chronic ulceration of the legs, two with infected bedsores, and one with severe chronic ulceration of the scalp. All except one were given parenteral and topical treatment. The infection, which had proved resistant to other forms of treatment, was eradicated in six. The two cases that did not respond had severe underlying disease involving the affected areas-diabetic neuropathy and peripheral vascular disease in one, and cardiac oedema in the other. Infected wounds (five cases).-Three patients had infected laparotomy wounds. In two the infection was eradicated, but the third died from the underlying surgical conditions. The fourth patient had an infected wound resulting from compound fracture of the tibia, which had resisted various forms of treatment for a month. Systemic and local treatment with colistin eradicated the infection in 5 days. The fifth patient, who had an infected amputation stump, showed good clinical improvement with parenteral and topical treatment, but the organism could still be obtained after 6 weeks. Pistulae (two cases).-One patient with a fistula of the gallbladder was cured of longstanding infection. This required a long course of treatment in large dosage (297 mega units in 52 days), and cure was not achieved until the dosage was increased from 1-5 to 3 mega units 8-hourly. The other patient had a chronic fistula, probably resulting from diverticulitis. It did not heal though Ps. pyocyanea was eliminated. Ear infections (four cases).-These were treated parenterally and with ear drops containing colistin. All four cases had a long history of chronic discharge, for which no treatment had been effective, and the production of dry ears in three was regarded as a very good result. Nasal sinusitis (one case).-Persistent pseudomonas infection was eradicated after parenteral treatment for 6 days and instillation of colistin into both antra on one occasion. Chest infection (one case).-This patient, with pulmonary fibrosis, died of respiratory failure after a portacaval shunt operation for oesophageal varices and cirrhosis. Infection was still present when he died. Severe burns (one case) and postoperative meningitis (one case). -Ps. pyocyanea infection was successfully eradicated in both patients. Unfortunately they died-one from a pulmonary embolus, and the other probably from brain-stem damage after the operation. In the patient with meningitis, colistin was given by daily intrathecal injections of 200,000 units as well as by intramuscular injections of 3 mega units 8-hourly.

Side-effects Treatment with colistin was given for 2 to 52 days (mean 16 days). The total intramuscular dosage varied between 9 and 297 mega units (mean 81-5 mega units). The only side-effect was parassthesiae of the face in one patient. This developed after 6 injections, and it cleared when treatment was stopped. Topical applications were used in twelve cases without any local reaction.

Bacteriological Results The minimum inhibitory concentration (M.iC.) of colistin, determined by the serial tube-dilution technique, was found to lie between 2 and 16 g. per ml. for fifty-five strains of Ps. pyocyanea; one strain was inhibited by 31 tg. per ml. The minimum bactericidal concentration (M.B.c.), determined by

subculturing a loopful of broth from the appropriate tubes, was average 21/2 times the M.i.c. Most strains were also tested by the disc technique (300 fLg. colistin per 9 mm. disc) when zones of inhibition measuring 12-20 mm. were obtained. Daily specimens were examined in twenty-six cases under treatment, and the sensitivity of the organism remained unchanged; the time of exposure to the drug ranged from 2 to 44 days. Mutants on

resistant to 120 fLg. per ml. colistin could be selected in vitro from sensitive Ps. pyocyanea strains; but their colonial morphology was atypical, and in the absence of the drug they rapidly reverted to their original sensitivity. None of the Ps. pyocyanea strains from thirty-one patients was sensitive by the disc technique to streptomycin, chloram-

phenicol, tetracycline, nitrofurantoin, neomycin, bacitracin, kanamycin, or ampicillin; but of 22 strains tested all were sensitive to polymyxin B (240 units per disc). Though Ps. pyocyanea was eradicated, Proteus strains were not uncommonly recovered during and after treatment; these strains

were

resistant

per ml. in broth.

to

300 g. discs and to 250 (J.g. colistin

Occasionally other resistant coliform organisms

seldom detected at the outset, but it whether they were present originally or subsequent infection. Colistin was measured in the serum and urine of six patients undergoing treatment, using a strain-of Escherichia coli supplied by Dr. A. T. Wallace (City Hospital, Edinburgh) as test organism. After intramuscular injections of 1-5 mega units (2 mg. per kg.) and 3 mega units (4 mg. per kg.) maximum blood-levels of 11-14 g. per ml. and 17-25 jg. per ml. respectively were achieved in 2-3 hours. These levels were maintained for 5-6 hours, and then they fell progressively. Two patients with cardiovascular disease showed low serum levels with flattened curves. The urine levels of colistin varied with the fluid intake, but the colistin/creatinine ratio closely followed the serum-colistin level. In the absence of diuresis, the urinary colistin reached more than 200 g. per ml. after a dosage of 1-5 mega units, but when fluid intake was high values of 20 g. or less per ml. were found. were

isolated. They

is impossible had arisen by

were

to say

These observations suggest that the blood-levels of colistin after 1-5 mega units exceeded for 3 hours or so the M.LC. of two-thirds of the strains of Ps.pyocyanea tested, but that only a quarter of the strains encountered bactericidal levels. A dosage of 3 mega units, however, produced serum-levels exceeding the M.i.C. in all but 1 strain and exceeding the M.B.c. in over half the strains. This rather narrow margin might account for the long time taken to eradicate the organism in some cases, while factors such as local difficulty in the drug penetrating to the site of the lesion, a very high concentration of organisms, or possibly slow absorption of the drug into the circulation may also play a part. The good response shown by two patients when given 3 mega units 8-hourly suggests that the higher dose should be used more often.

Summary A clinical and bacteriological study of forty patients has demonstrated that colistin methane sulphonate (’Colomycin’) is effective in the treatment of infections with Pseudomonas pyocyanea. In the dosage employed, there were no serious toxic effects. The standard intramuscular dosage of 1-5 mega units 8-hourly, used in this study, was adequate for most cases, but some have needed twice this

dosage. Colistin methane sulphonate (’Colomycin’) was supplied by Messrs. Pharmax Ltd., and we should like to thank their medical adviser, Dr. M. F. Cuthbert, for his cooperation. This trial was part of a combined clinical study in which the following have also contributed: Dr. N. Southwell, Dr. J. D. Williams, Dr. F. C. Herman, and Dr. K. Randall, of Orpington and Sevenoaks Hospitals, and Queen Mary’s Hospital, Sidcup; Dr. A. G. C. Cox and Dr. J. Fullerton, of the Bermondsey and Southwark Group of Hospitals; and Dr. K. S. MacLean, of the department of medicine, and Prof. R. Knox, of the department of bacteriology, Guy’s Hospital.

739 We should like to thank the physicians and surgeons who have allowed us to treat their patients. REFERENCES

Barber, M. (1961) J. clin. Path. 14, 2. Carroll, G., Malette, W. F. (1961) J. Urol. 85, 86. Chabbert, Y. A. (1958) Minerva med. 2, 4482. Curtin, J. A., Petersdorf, R. G., Bennett, I. L. (1961)

Ann. intern. Med.

54,

1077.

Cuthbert, M. F. (1962) Lancet, i, 383.

Derot, M., Goury-Laffont, M., Albouy, M. (1961) Gaz. med. Fr. 68, 1169. Finland, M., Jones, W. F., Barnes, M. W. (1959) J. Amer. med. Ass. 170, 2188.

Forkner, C. E., Jr., Frei, E., Edgcomb, J. H., Utz, J. P. (1958) Amer. J. Med. 25, 877. Forni, F. V., Guidetti, E. (1956) Minerva med. 2, suppl. 77, p. 823. Koyama, Y. (1950) J. Antibiot. 3, 457. Lancet (1962) i, 88. Petersdorf, R. G., Hook, E. W. (1960) Bull. Johns Hopk. Hosp. 107, 133. Rabin, E. R., Graber, C. D., Vogel, E. H., Finkelstein, R. A., Tumbusch, W. A. (1961) New Engl. J. Med. 265, 1225. Schwartz, B. S., Warren, M. R., Barkley, F. A., Landis, L. (1959-60) Antibiot. Annu., p.41. Traegar, J., Pellet, M., le Tellier, H. (1961) Rev. lyon. Méd. 10, 1085. Wright, W. W., Welch, H. (1959-60) Antibiot. Annu. p. 61. Yow, E. M., Tan, E., Shane, L., Schonfield, S., Abu-Nassar, H. (1961) Arch. intern. Med. 108, 664.

A TRIAL OF

COLISTIN METHANE SULPHONATE IN URINARY INFECTION WITH Pseudomonas pyocyanea W. M. EDGAR M.D. Cantab. SENIOR LECTURER IN BACTERIOLOGY, WESTMINSTER MEDICAL SCHOOL, LONDON,

S.W.I

K. M. DICKINSON M.B. Manc., F.R.C.S. SURGICAL REGISTRAR, DEPARTMENT OF UROLOGY, WESTMINSTER HOSPITAL, LONDON, S.W.1

ATTEMPTS

infections caused by Pseudomonas often unsuccessful. Many strains of the resistant to almost all chemotherapeutic

to cure

pyocyanea

are

organism

are

initially sensitive may become resistant There are available only two antibiotics to which nearly all strains remain sensitive, and which are not too toxic to be given parenterally-namely, polymyxin B and colistin. The exact relation between colistin and members of the polymyxin group has not been finally elucidated (Cuthbert 1962, Stewart 1962). Polymyxin B is available for parenteral administration as the sulphate, and colistin as the methane sulphonate (‘ Colomycin ’). There is no doubt that polymyxin B sulphate causes pain at the site of injection (Swift and Bushby 1953, Yow and Moyer 1953), and there is evidence of nephrotoxicity (Hopper et al. 1953, Yow and Moyer 1953). It often has neurotoxic effects (Jawetz 1952, Hopper et al. 1953), though these usually disappear 1 to 2 days after the drug is stopped (Kagan et al. 1951). On the other hand, it is claimed that colistin methane sulphonate does not cause pain at the site of injection (e.g., Carroll and Malette 1961), there is no evidence that it is nephrotoxic (Blaustein 1959-60, Yow et al. 1961), and its mild neurotoxicity does not seem to contraindicate its use (Yow et al. 1961). It has been reported recently that the methane sulphonate of polymyxin B is neither nephrotoxic nor neurotoxic (Clifford and Stewart 1961), but this compound has not yet been released for general use. We here describe a trial of colistin in ten patients who had urinary infections caused by Ps. pyocyanea.

agents, and strains

during

treatment.

The Trial

patients represent the " hard core " of the urological department. All had severely damaged urinary tracts, and in all but two patients renal function as shown by intravenous pyelography was poor. The duration of the infection ranged from 1 month to 6 years, and all the The

SUMMARY OF THE CASE-HISTORIES