1045

generally be the cessation of pelvic irradiation.

present aspirin should

given

to

patients onlv after

TABLE 11-ACTIVITY OF FOUR AMINOGI YCOSIDI S ACAINST

98

STRAINS OF

PROVIDFNCIA STl’ARTII

M.R.C. Gastroenterology Unit, Central Middlesex Hospital, Park Royal, London NW10 7NS.

R. E. POUNDER

PROVIDENCIA STUARTII INFECTIONS

SIR,-Recent reports’-3 have focused attention on Prcr! dencia stuartii as a cause of hospital-acquired infection. Significantly, these organisms are usually resistant to4 most commonly used antimicrobials including gentamicin.2 Infections of the urinary and respiratory tracts, wounds, and blood have all been reported. Curreri et al.,5 from a burns unit in Houston, Texas, have documented over a two-year period a rising incidence of infection due to Providencia Stuartii. Providencia pneumonia and bacterxmia occurred with greater frequency than similar infections with Pseudomonas aeruginosa and appeared to be equally lethal in their burned patients. We report here our experience with Providencia stuartii infections over a

three-year period.

All the strains were isolated from clinical material at the central microbiology department, federated Dublin Voluntary Hospitals, over a three-year period ending December, 1974. This laboratory serves six hospitals. Identification was by the TABLE I-SITE OF INFECTION IN

105

PATIENTS WITH PROVIDFNCIA

STUARTII INFECTION

biology, Dudley Road Hospital, Birmingham. The activity of four drugs-kanamycin, gentamicin, tobramycin, and the new aminoglycoside, amikacin-were studied by a routine agarplate dilution method. Oxoid D.S.T. agar and an inoculum of 105 organisms/ml were employed. If a reasonable therapeutic level of kanamycin and amikacin is considered to be 16 mg/1 and of gentamicin and tobramycin 4 mg/1, then only 13.2% and 16.4% of strains can be regarded as sensitive to gentamicin and tobramycin respectively. 76.5% can be regarded as sensitive to kanamycin and 100% sensitive to amikacin. Disc-sensitivity testing was also performed using ampicillin(A), sulphonamide(S), streptomycin(St), cotrimoxazole (Cot), chloramphenicol(Ch) and colistin(Ct) antibiotic discs. 85% were resistant to all these drugs. 1 isolate was sensitive to A, St, S, and Cot; 1 to St and Cot; 1 Cot alone; and 3 to St, S and Cot.

to

S, Cot, and Ct; 2

The high numbers of strains resistant to gentamicin may well be related to the amount of this antibiotic used in our hospitals. We have no precise information on this, but certainly over the last four years this drug has become the antibiotic of choice for serious gram-negative infections. On these results kanamycin is the drug of choice until aminkacin is available. Owing to the specific antibiotic sensitivity, the identification on primary culture is important. We have found that Providencia stuartii on all solid media routinely used has a characteristic odour which is distinct from Proteus species which it resembles in many respects. Central

method of Bascome et al.6 and A.P.I. and Minitek systems. Standard criteria of the clinical significance of the isolates were used.’ Cultures from blood and urine were invariably pure, those from wounds, burns, and sputa frequently mixed. Most patients had had antecedent antimicrobial therapy including gentamicin. Table I shows the number of infected patients for the three-year period according to site. The frequency of isolation increased in the period under study and the total number of patients with infections caused by this organism up to the beginning of September this year equalled the total for 1974. The first 2 cases of septicaemia occurred last year, and both patients were treated blindly with gentamicin after blood-cultures had been taken. The isolates were resistant to this antibiotic and the patients died. Many of the isolates from other sites also appeared to be playing a pathogenic role. To explain the increased isolation-rate the possibility of cross-infection must be entertained. This was probably a factor as there were some instances of clustering. However, most cases appeared unrelated to others. We have found biochemical reactions’ unhelpful when trying to discriminate between cultures of this species and are at present investigating the use of serology and provicine typing in epidemiological investigations. The minimal inhibitory concentration (MIC) of 98 first isolates (7 isolates failed to survive subculture) to aminoglycosides likely to be effective in therapy is shown in table n.These tests were performed in the department of medical micro1. Solberg, C., Matsen, J. M. Am. J. Med. 1971, 50, 241. 2. Overturf, G. D., Wilkins, J., Ressler, R. J. infect Dis. 1974, 129, 353. 3 Klastersky, J., Bogaerts, A. M., Noterman, J., Van Laer, E., Didier, D., Mouawad, E. Scand. J. infect. Dis. 1974, 6, 153. 4. Reynolds, A. V., Hamilton-Miller, J. M. T., Brumfitt, W. Br medJ 1974, iii, 778 5 Curreri, P. W., Bruck, H. M., Lindberg, R. B., Mason, A D., Pruitt, B. A.

Ann. Surg. 1973, 6. Bascome,

177, 133. S., Lapage, S. P., Curtis, M. A., Willcox, W. R. J.

1973, 77, 291.

gen. Microbiol.

to

Microbiology Laboratory, Adelaide Hospital, Dublin

8.

Department of Medical Microbiology, Dudley Road Hospital, Birmingham B18 7QH.

C. T. KEANE L. F. ENGLISH

R. WISE

CONTRACTILE PROTEINS IN EXPERIMENTAL AND HUMAN NEOPLASIA

Six,-The report by Professor Gabbiani and others (Oct. 25, p. 796) of an increase in contractile proteins in human cells confirms

results and conclusions on the rabbit and rat skin carcinomas, examined with smooth-muscle antibody (S.M.A.), immunofluorescent staining of cell outlines in the basal parts of the tumours. Weaker staining was observed in adjacent tumour cells and the most superficial better-differentiated tumour cells were negative. Invasive tumour in the dermis showed the greatest reactivity with S.M.A. In contrast, histologically benign tumours showed less basal staining, and normal epidermal cells were negative. We concluded that the staining reveals cytoplasmic contractile microfilaments, and postulated that they might facilitate local tumour invasion. The less extensive staining observed in benign lesions is in keeping with their limited growth potential. In four human and four experimental rat astrocytomas stained with S.M.A., we observedincreased staining in neoplastic cells as compared with normal astrocytes; we also demon-

cancer

same

our own

topic. We showedl-3 in chemically induced

1. Muller, H. K., Flannery, G. R., Toh, B. H., Kalnins, R Proceedings of Pacific Congress of Dermatology, Sydney, June, 1975; p. 14. 2. Toh, B. H., Muller, H. K. Proceedings of Australian Society for Experimental Pathology, Canberra, August, 1975; p 5. 3. Toh, B. H., Muller, H. K. Cancer Res. (in the press). 4. Toh, B. H., Muller, H. K., Elrick, W. L. Br. J. Cancer, (in the press).