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 ~  Abstract
 ~  Materials and Me...
 ~  Results
 ~  Discussion
 ~  Acknowledgement
 ~  References

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BRIEF COMMUNICATION
Year : 2004  |  Volume : 22  |  Issue : 3  |  Page : 175-178
 

Bacteriology of diabetic foot lesions


Department of Microbiology, Rajah Muthiah Medical College and Hospital, Annamalai University - 608 002, Tamil Nadu, India

Date of Submission06-May-2003
Date of Acceptance19-Sep-2003

Correspondence Address:
Department of Microbiology, Rajah Muthiah Medical College and Hospital, Annamalai University - 608 002, Tamil Nadu, India

 ~ Abstract 

Clinical grading and bacteriological study of 107 patients with diabetic foot lesions revealed polymicrobial aetiology in 69 (64.4%) and single aetiology in 21 (19.6%). Among 107 patients 62 had ulcer. Of these 31 had mixed aerobes. Twenty six patients with cellulitis and 12 with gangrene had more than 5 types of aerobes and anaerobes such as E.coli, Klebsiella spp., Pseudomonas spp., Proteus spp., Enterobactor spp., Enterococci spp., Clostridium perfringens, Bacteroides spp., Prevotella spp. and Peptostreptococcus spp. It was noted that 50 out of 62 patients with ulcer, and all the patients with cellulitis and gangrene were given surgical management and treated with appropriate antibiotics based on antimicrobial susceptibility testing.

How to cite this article:
Anandi C, Alaguraja D, Natarajan V, Ramanathan M, Subramaniam C S, Thulasiram M, Sumithra S. Bacteriology of diabetic foot lesions. Indian J Med Microbiol 2004;22:175-8


How to cite this URL:
Anandi C, Alaguraja D, Natarajan V, Ramanathan M, Subramaniam C S, Thulasiram M, Sumithra S. Bacteriology of diabetic foot lesions. Indian J Med Microbiol [serial online] 2004 [cited 2019 Oct 18];22:175-8. Available from: http://www.ijmm.org/text.asp?2004/22/3/175/11213


Diabetes mellitus is a chronic disorder and affects large segment of population and is a major public health problem. Diabetes and foot problems are almost synchronous.[1],[2],[3],[4] The trio of problem leading on to the diabetic foot is neuropathy, vascular changes and infections, which constitute the diabetic foot syndrome.[5],[6] Infection complicates the pathological picture of diabetic foot and plays a main role in the development of moist gangrene.[4],[5],[6] Pseudomonas spp., Enterococcus spp. and Proteus spp. carry a special role and are responsible for continuing and extensive tissue destruction with the poor blood circulation of the foot.[5],[6],[7] A high frequency of anaerobic infection has also been reported.[7],[8],[9] The infection leads to the early development of complication even after a trivial trauma, the disease progresses and becomes refractory to antibacterial therapy.[10] It is essential to assess the magnitude of bacterial infection of the lesions to avoid further complications and save the diabetic foot. Early diagnosis of micorbial infections is aimed to institute the appropriate antibacterial therapy and to avoid further complications. In view of the above, a prospective microbiological study was carried out and results are presented here.

 ~ Materials and Methods Top

A total of 107 patients with diabetic foot lesions from surgery unit of Rajah Muthiah Medical College hospital were screened between March 2000 and March 2002. These patients were clinically assessed and the foot lesions were graded depending on the severity of lesions[2],[5] as grade 0 - no obvious ulcer, but thick callus, prominent metatarsal heads, claw toes or any bony abnormality; grade 1 - superficial ulcer clinically not infected; grade 2 - deep ulcer often infected but no bone involvement; grade 3 - deep ulcer, abscess formation and bone involvement; grade 4 - localized gangrene and grade 5 - gangrene of whole foot.
Discharge from the incised lesions or ulcers was collected with sterile swabs. Pus aspirates from the abscesses and debrided necrotic materials were collected for aerobic and anaerobic culture. A Gram stained direct smear of the specimen was examined. The specimens were cultured on blood agar, MacConkey agar, thioglycollate broth and Robertson's cooked meat media for aerobic and anaerobic culture. In addition, the specimens from patients with cellulitis and gangrene were inoculated into lysed blood agar with vitamin K, and neomycin blood agar and egg yolk agar for anaerobic culture.
The bacterial isolates were identified by conventional biochemical tests.[11] The  Clostridium perfringens  /i>was identified by Nagler's reaction using specific anti-gas gangrene serum.[11] The antibacterial susceptibility testing was done according to Kirby- Bauer method.[9] The patients were treated with antibacterial agents according to culture and antibacterial susceptibility pattern. Dressings were done twice daily, surgical interventions were done wherever needed for cellulitis and amputation was done for patients with gangrene.

 ~ Results Top

Among 107 patients with diabetic foot from surgical units, 70 were male and 37 were female patients and the age ranged from 17 to 66 years with mean age being 43 years. The number of patients who were graded based on the foot lesions and the number of types of bacterial isolates are given in [Table - 1].
The number of patients graded into each grade of 0,E.coli  class="ref" name="ft1" href="#ref1">1,E.coli  class="ref" name="ft2" href="#ref2">2,E.coli  class="ref" name="ft3" href="#ref3">3,4 and 5 were 32,30,18,E.coli  class="ref" name="ft10" href="#ref10">10,9 and 8 respectively. Aerobic bacteriology culture yielded 177 aerobes [Table - 2]. Anaerobic bacteriology culture included 45 isolates from 4 patients with cellulitis and 12 gangrene patients with gangrene [Table - 2].
Antibacterial susceptibility testing revealed that Proteus spp. (92%), Pseudomonas spp. (84%),  E.coli   (97%), Klebsiella spp. (94%) and Enterobacter spp. (90%) were susceptible to ciprofloxacin, ofloxacin and pefloxacin. All the aerobes were sensitive to amikacin and gentamicin except two Pseudomonas spp. isolates. All the aerobes and anaerobes were susceptible to cefotaxime except four Pseudomonas spp. isolates which were susceptible to amikacin and gentamicin. The bacterial isolates from each category of patients with ulcers, cellulitis and gangrene varied from one to more than three types. Single type of bacterial isolate was found in 21 out of 90 patients with ulcers and cellulitis. Polymicrobial infections i.e., > 2 types of bacteria were found in 69 patients. Bacteriology culture yielded negative results in 17 patients with ulcers. Gangrene of the foot was noted in 17 patients and they were mostly of the moist type of infection. Clostridium perfringens was isolated from 7 patients. All these 17 patients had polymicrobial type of infections. The patients with cellulitis and gangrene had mixed aerobic and anaerobic bacterial infections and were treated according to culture and sensitivity pattern for 10 to 14 days. Fifty nine out of 107 patients were treated with injection cefotaxime and 25 patients were treated with injection ampicillin and gentamicin. In patients with gangrene and cellulitis, incision and removal of dead tissue and the drainage of pus along with antibacterials controlled the spread of infection. Transmetatarsal amputation was done in two patients and below knee amputation was in 12 and above knee amputation was done in two patients.

 ~ Discussion Top

Aerobic and anaerobic infections in diabetic ulcers and lesions have been studied extensively[12],[13],[14] and found the predominance of Pseudomonas spp., Proteus spp. and Bacteroides spp. infection among them. Among 107 patients in this study 62 (57.9%) had ulcers categorized into grade 0 and 1. Most of these patients presented with trophic ulcer, which had punched out edges and were common in the heel of the foot. The surrounding areas were inflamed and oedematous. Twelve patients with ulcer revealed three types of mixed bacterial infection; (a) four patients had Pseudomonas spp., E.coli and S.aureus; (b) six patients had Proteus spp. and S.aureus and (c) two patients had Enterobacter spp., Proteus spp. and S.aureus. No anaerobes was isolated from the patients with ulcers. Single type of bacteria was isolated in 19 patients. On the other hand 26 patients with cellulitis and 12 patients with gangrene had more than 5 types of aerobes mixed with anaerobes. It is interesting to note that 15 patients who had S.aureus infection of ulcers responded well to oral cloxacillin / ciprofloxacin therapy given for 10 to 14 days. In five patients from whom Proteus spp. was isolated the ulcer was slightly bigger and had serosanguinous discharge who responded to cefotaxime given for 10 days. The 62 patients with ulcers were followed up for two years in “diabetic foot clinic”. As per Smith et al[5] several factors were taken into consideration for diabetic foot apart from antibacterial therapy. They include the patients environment, the nature of initial injury and whether or not the infection was life threatening. In our patients, apart from controlling the diabetes and antibacterial therapy, complete foot care was given which included foot inspection, patient education and prescription of special shoes and exercises. It was noted that 50 out of 62 patients who attended the diabetic clinic regularly did not develop further complications on further follow-up of six months to two years and the lesions healed well. The remaining 12 patients who had discontinued antidiabetic drugs developed cellulitis in 10 and gangrene in two patients.
It is interesting to note that methicillin resistant S.aureus was noted only in five out of 24 S.aureus isolates from 107 patients.
In conclusion, pus culture and sensitivity testing played an important role in the treatment of infection in patients with cellulitis and gangrene. Bacterial culture helped 50 out of 62 patients with ulcer in not only to treat the infection but also prevented the patients from developing further complications like cellulitis and gangrene.

 ~ Acknowledgement Top

We acknowledge Prof. PV Hayavadhana Rao, Dean Rajah Muthiah Medical College and administrative officers for permitting us to do this work. 

 ~ References Top

1.Frykberg RG. Diabetic foot ulcers: current concepts. J Foot Ankle Surg 1998;37(5):440-446.  Back to cited text no. 1    
2.Blazer K, Heidrich M. Diabetic gangrene of the foot. Chirurg 1999;70(7):831-844.  Back to cited text no. 2    
3.Logerfo FW, Coffman JD. Current concepts. Vascular and microvascular diseases of the foot in diabetes. N Engl J Med 1984;311:1615-1619.   Back to cited text no. 3    
4.Shea KW. Antimicrobial therapy for diabetic foot infections. A practical approach. Postgrad Med 1999;106(1):85-86, 89-94.  Back to cited text no. 4    
5.Smith JMB, Payne JE, Berue TV. Diabetic foot lesions of skin and soft tissue infections of surgical importance. Chapter 14. In The surgeons Guide to Antimicrobial Chemotherapy 2002:218-221.  Back to cited text no. 5    
6.Meade JW, Muller CB. Major infections of the foot. Med Times 1968;96:154-165.  Back to cited text no. 6    
7.Bailey TS, Yu HM, Rayfield EJ. Patterns of foot examination in a diabetic clinic. Am J Med 1985;78: 371-374.  Back to cited text no. 7    
8.Miler RS, Amyes SGB. Laboratory control of antimicrobial therapy. Chapter 8 In Mackie and MC Cartney Practical medical Microbiology. edi. by Collee JG, Frases AG, Marmion BP Simmons A (14th edition published by Churchill Livingston ) 1996:151-178.  Back to cited text no. 8    
9.Forbes BF, Sahn DF, Weisf AS. Anaerobic bacteriology Laboratory consideration chapter 59 section 12 In Bailey and Scott's Diagnostic Microbiology. 10th ed published by Mosby. 1998:696-710.  Back to cited text no. 9    
10.Pittet D, Wyssa B, Herter-Clevel C, Kursteiner K, Vaucher J, Lew PD. Outcome of diabetic foot infections treated conservatively a retrospective cohort study with long term follow up. Arch Inter Med 1999;159(8):851-856.  Back to cited text no. 10    
11.Pathare NA, Bal A, Talvalkar GV, Antani DV. Diabetic foot infections a study of microorganisms associated with the different Wagner grades. Indian J Pathol Microbiol 1998;41(4):437-441.  Back to cited text no. 11    
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