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A Microbiological Study of Diabetic FootLesionsEmyr W. Jones*, Richard Edwardst, Roger Fincht, Will iam J . Jef fcoate** Department of Diabetes and ndo crinology, The City Hospital,Nott ingham NC5 IPB, U.K.t Department of Microbial Diseases, The City Hospital, and the PublicHealth Laboratory and Department of Microbiology, UniversityHospital, Nbtt ingham NC 7 ZUH, U.K.

The bacterial nature of infected foot lesions presenting to a diabetic unit during thecourse of twelve months was studied. Fifty-six swabs were obtained from 25 patients.Swabs were processed within ten minutes of being collected. An average of 3.3organisms per swab were isolated, Staphylococcus aureus was the most commonbacterial species isolated, while anaerobic bacteria comprised 10% of the isolates.Sensitivity testing of the isolates against commonly used antibiotics showed that theantimicrobial regimen that we have previously used empirically on such patients maynot always be optimal.KE Y WORDS Diabetes mellitus Microbiology Infection Foot lesions FlucloxacillinFusidic acid Amoxycillin Clavulanic acid Metronidazole

IntroductionPatients with diabetes mellitus have an increased suscep-tibility to infection, especially infected foot lesions.Patients at risk are the elderly and those with neuropathyand vascular insufficiency.2.3 Once established, infectionmay extend to adjacent tissues, causing cellulitis oro~teomyelitis,~nd occasionally bacteraemia.5 Ulcer-ation and infection of the foot account for the use ofmore hospital bed days than any other complication ofdiabetes.6 The management varies widely, especially inthe choice of topical and systemic antimicrobial therapy.Agents effective against staphylococci and streptococci7and anaerobic bacteria, are widely used, although thechoice remains largely empirical. Reliable informationon the bacteria involved in diabetic foot ulcers is scanty,and prospective studies of antimicrobial treatment havenot been reported. We have undertaken a detailedprospective bacteriologial study of such lesions present-ing to a diabetic unit during the course of twelve months,with a view to assessing whether the widely used combi-nation of flucloxacillin or fusidic acid with metronidazoleis appropriate.

purulent exudate, subcutaneous gas or radiological evi-dence of osteomyelitis, and samples taken wheneverpossible before the start of antimicrobial therapy. Themethod of sampling was by vigorous rubbing of a salinemoistened cotton-wool-tipped swab, at the deepest ac-cessible area of the lesion, and also at the sites of anyvisible exudate. All samples were examined by Gramstain and, within 10 minutes of collection, were inoculat-ed onto culture media and incubated at 37OC: aerobical-ly on blood agar and MacConkey agar; in 5 % CO, onblood agar; anaerobical ly on pre-reduced blood agarand neomycin selective (Oxoid) medium (containingbrain-heart infusion agar, 0.05% cysteine hydrochlo-ride, 1o/o Vitamin K-haemin solution, 0.5% yeast extract,100 mgll Neomycin, and horse blood), and in thioglyco-late broth. The aerobic and 5% C O , plates were exam-ined after 1, 3 , and 7 days and the anaerobic plates after3 and 7 days. All isolates were identified by standardmethods,B and gas-liquid chromatography was used todetect the presence of anaerobic organisms in the thiog-lycolate broths.9 Sensitivity for amoxycillin/clavulanicacid, flucloxacillin, metronidazole, and fusidic acid weretested by the comparative disc method on DST (Oxoid)agar supplemented with lysed horse blood.

Patents and Methods ResultsTwenty-five diabetic patients, who presented with clini-cally infected foot lesions to the City Hospital, Notting-ham, over a 12-month period, were studied. Clinicalinfection was identified by the presence of cellulitis,Correspondence to : Dr. E. W. Jones, Department of Med ic ine ,Universi ty Hospi ta l , Not tingham, NG7 2 UH , U.K .

Swabs were taken from foot lesions in 14 diabetic menand 11 diabetic women, mean age 68 years (range 43-91years). In 7 patients, diabetes had not previously beendiagnosed and in the remaining 18 patients, the meanduration of diabetes was 21 years (range 5-53 years).Sixteen patients were treated with insulin, 4 with a

0 985 by John Wiley & Sons, Ltd.DIABETIC MEDICINE, VOL. 2,213-215 (1985) Accepted 10 October 1984 213

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CLINICAL AUDIT Dmcombination of diet and oral hypoglycaemic agents and5 with diet alone. Twenty-two patients had evidence ofperipheral arterial insufficiency (absent pulses in leg andfoot) and 15 of these had clincial signs of coincidentperipheral neuropathy. Three patients had signs ofperipheral neuropathy, but without evidence of periph-eral arterial disease. A variety of lesions were studied:infected neuropathic ulcers on the sole; ischaemicgangrene; traumatic lesions, and lesions at sites of abnor-mal pressure. X-rays of the foot showed osteomyelitis in3 patients and subcutaneous gas in 1.

From the 56-swabs taken from the 25 patients, 185bacterial isolates were recovered, giving an average of3.3 isolates per sample (range 1-6). Thirteen of the swabshad been taken from patients who had received systemicantibiotics in the previous 7 days. The number of isolatesfrom these swabs (mean 2.8 isolates per sample, range1-5) was significantly lower than the number of isolatesfrom swabs taken when there had been no precedingantibiot ic treatment (mean 3.5 isolates per swab, range1-6) @

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DT17 CLINICAL AUDITinfection may be opportunist. Furthermore, penetrationof systemic antimicrobials into the infected lesion maybe sub-optimal, produc ing ineffective tissue concentra-tions. It i s noteworthy i n this respect that, in this study,many of the swabs taken from patients wh o had receivedrecent systemic antibiotics grew organisms sensitive tothe antibiotics which had been used, suggesting that thesystemic antibiotics had for some reason been ineffectivein eradicating susceptible organisms. Antimicrobialsmay, however, be necessary to prevent spread of infec-tion to adjacent bone or soft tissue, o r to preventbacteraemia with haematogenous spread of infection todistant sites. These factors require extensive study.

This study has shown that the majority of organismsisolated were resistant to the antimicrobial drugs com-monly used in the treatment of infected diabetic footlesions in Nottingham (and presumably in many othercentres) and further critical study of the use of systemicantimicrobials in these lesions i s needed.

References1.2.3.4.

Wheat LJ, Infection and diabetes rnellitus. Diabetes CareAnon. Diabetic foot ulcers. Lancet 1977; 1: 231-233.Anon. Diabetic feet. Br Med1 1977; 1: 338.Waldogel FA, Medoff G, Swartz MN. Osteornyelitis: areview of clinical features, therapeutic considerations and

1980; 3: 187-197.

unusual aspects. N Engl j Me d 1970; 282: 198-206, 260-5. Sapico FL, Bessrnan AN, Canawati HN. Bacteraernia indiabetic patients with infected lower extremities. DiabetesCare 1982; 5: 101-104.6. Ward JD, The diabetic leg. Diabetologia 1982; 22: 141-147.7. Watk ins PI. Diabetic neuropathy-1. B r Me d 1 1982; 285:8. Cowen, Steel. Manual for the ldentifi cation of MedicalBacteria, 2nd edn. Cambridge: Cambridge UniversityPress, 1974.9. Holdeman LV, Cat0 EP, Moor e WEC (Eds). AnaerobeLaboratory Manual, 4th edn. Blacksburg: Virginia StateUniversity, 1978.10. Pratt TC. Gangrene and infect ion in the diabetic. Me d ClinNorth Am 1965;49:987-1 004.11. Williams HGT, Hutchinson KJ, Brown GD. Gangrene ofthe feet in diabetes. Arch Surg 1974; 108: 609-61 1.12. Louie TJ, Bartlett JG, Tally FP, Gorbach SL, Aerobic andanaerobic bacteria in diabetic foot ulcers. Ann lnter Med

13. Sharp CS, Bessman AN, Wagner FW, Garland D.Microbiology of deep tissues in diabetic gangrene.Diabetes Care 1978; 1: 289-292.14. Sharp CS, Bessrnan AN, Wagner FW, Gar land D,Reece E.Microbiology of superficial and deep tissues in infecteddiabetic gangrene. Surg Cynaecol Obstet 1979; 149:217-219.15. Sapico FL, Canawati HN, Witte J L , Montgornerie J Z ,Wagner FW, Bessrnan AN. Quantitative aerobic andanaerobic bacteriology of infected diabetic feet. ClinMicrobiol 1980; 12: 413-420.

266, 316-322.

492-495.

1976; 85; 461-463.

MICROBIOLOGY OF FOOT ULCERS 215

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M E D I A REVIEW DmEdited by Edwin Gale

Diet and Diabetes by Briony Thomas.Churchill Livingstone. No. of pages: 97 .Price: f 1.95.Briony Thomas has been closely associat-ed with the recent developments in thedietary management of diabetes. Her re-search has involved studying the relation-ship between diet and complications ofdiabetes; she i s a member of the BritishDiabetic Association Nutrition Subcom-mittee (which recently recommendedmajor changes in the diabetic diet) andshe has a great deal of practical exper-ience as a dietitian. I t i s hardly surprisingtherefore that she has produced a wellwritten, brief but comprehensive book ondiet and diabetes. The book covers theprincipals as well as practical applicationsof almost all relevant aspects and i s com-plementary to the several diet and recipebooks already available.

This i s not primarily a recipe book, butsome sample recipes are included as areminder of how palatable the new dia-betic way of eating can be for the wholefamily. There are a small number ofpoints which we feel would have benefit-ted from expansion or modification: It i simportant to emphasize that not all typesof dietary fibre are equally beneficial, thesoluble or gel-forming fibres (e.g. asfound in cooked dried beans) have moremarked effect than most of the othervegetables and cereal fibres. While agree-ing that diabetic patients on oral hypogly-caemic agents should have regular mealsit i s in our opinion unnecessary to implythat this is as important as for insulintaking patients. Tables of good and badfoods are always difficult to compile andone on p. 16 needs to be interpreted witha little caution. Pastry made with whole-meal flour is reasonably included as a

good carbohydrate food but may behigh in fat and calories and therefore notoverall a particularly good food. All driedfruit i s also not always suitable sincecrystallized fruit may be included in thiscategory. Porridge s described as moder-ately good; yet porridge oats may bepreferable to some of the foods listed inthe good category. Fish pate (p. 39 ) i s notalways low calorie and not all supermar-ket own-brand squashes and soft drinkslabelled low calorie are sugar free (p. 64).These are not major criticisms and atf1.95 the most recent addition to theChurchill Livingstone patient handbookseries (which includes three other diabe-tes topics) can be recommended withouthesitation.M a r y Vun, J im M a n n/ o h n Radcliffe Hospital, Oxford OX3 9DU,U .K .

Announcing a new quarterly journal from Wiley, New York.. .D A BET ES /META BO1SMREVIEWSEditor :Ralph DeFronzo, MD,Yale U niversity Schoolof Medic ine,Ne w Haven, Connect icut ,USA

Published quarter lyF i r s t issue: Spring 1985Subscription: $8 5Outs ide US add $77 for surface or $5 6 for airmai lpostage and ha ndling

Diabetes/Metabolism Reports wi be devotedto serv ing the communi ty of researchers andcl in ic ians by prov id ing an ongoing update ofclinical and basic scientif ic advances i n themost important areas of diabetes andmetabol ism.Each issue wil l present invited art icles focusedon a given area in diabetes and metabol ism.Contr ibutors will be the wor lds outstandingresearchers and clinicians in th e f ield, thosewith th e credentials to report authoritatively onwork at the front ier of basic and cl in icalresearch.These authorities will repor t on and rev iewtheir o w n wo rk in a part icular area-in thecontext of previously pubi ished informat ionand current controversies. Areas of agreementand disagreement will be pointed o ut and thephysiologic and cl in ical importance of eachauthor s w ork will be stressed.

216 MEDIA REVIEW