The microbiology of diabetic foot infections in patients recently treated with antibiotic therapy: A prospective study from India

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Abstract

Aim

Clinicians often treat clinically infected diabetic foot ulcers without information from cultures of the wound. The results of wound cultures may also be affected by previous antibiotic therapy. Thus, we aimed to study the microbial isolates, and antimicrobial sensitivity of previously treated patients with a clinically infected DFU.

Research Design and Methods

293 consecutive patients with clinically infected DFU on prior antimicrobial treatment within the immediate past few days for a duration greater than one week were evaluated for microbial etiology, antibiotic sensitivity and final outcomes. Appropriate tissue samples i.e. purulent drainage, soft-tissue and/ or bone were obtained for aerobic/anaerobic cultures and antimicrobial sensitivities. 71 patients with missing prior antibiotic data were excluded.

Results

313 tissue samples obtained from 222 patients isolated 317 causative organisms. Most of the culture results from tissue specimens were mono-microbial (93.2%) compared to 37% in our previous cohort of 60 patients. Pseudomonas aeruginosa was the most common organism isolated on culture of bone (26.9%) or soft tissue (23.2%) specimen, respectively. Only 23% and 64% of P. aeruginosa isolates and 5.6% and 44% of Acinetobacter sp. were sensitive to quinolones and cephalosporins, respectively.

Conclusions

Clinically infected DFU recently treated with antibiotics have predominant monomicrobial and multi drug-resistant infection. Quinolones as an empirical antibiotic choice may not be appropriate in this setting.

Introduction

Diabetic foot ulcers (DFU) accounts for more than 20% of diabetes-related hospital admissions and most of the in-hospital DFU are associated with limb or life threatening diabetic foot infections (DFI). 1 DFI may involve either soft tissue or bone and appropriate culture sampling with early antibiotics administration is needed for curing infection (Glaudemans et al., 2015, Jeffcoate and Lipsky, 2004, Lipsky et al., 2012). Recently, the focus has been on medical management of osteomyelitis, because antibiotics given as primary treatment may have similar outcomes as surgical treatment (Lazaro-Martinez et al., 2014, Lipsky, 2014). The first 72 h are likely to be critical in limb salvage for clinically infected DFU and the key for management is the proper choice of initial empirical antibiotics, until the availability of definitive culture reports. The empirical antibiotic choice is guided by the history, clinical examination, severity of infection, likely etiological agent and previous antimicrobial sensitivity pattern from the treating units as also suggested by the Infectious Disease Society of America (IDSA) clinical practice guidelines for the diagnosis and treatment of diabetic foot infections (Lipsky et al., 2012).

It is not uncommon to come across DFI treated wrongly in clinical practice due to the lack of dedicated and specialized diabetic foot care units. These include the DFI treated with antibiotics without the availability of tissue culture and anti-microbial sensitivities or with agents likely to be inactive against the isolated pathogen or for antibiotics given for a wrong duration. This prospective study was planned to characterize the spectrum of pathogens, the in-vivo antimicrobial susceptibility amongst patients with clinically infected DFU who had prior received antimicrobials in the immediate past few days for a duration of more than seven days and compare the isolated microbes with our previous cohort of 60 patients (Parvez et al., 2012).

Section snippets

Study population

The data of all subjects with DFU are prospectively captured and entered in a repository with a standardized data collection format after obtaining an informed consent format at our tertiary diabetic foot care referral facility in North India comprising of a multi-disciplinary team of endocrinologist, internist, surgeon, vascular surgeon, podiatrist and nurse. Two hundred ninety three consecutive patients presenting with clinically infected DFU who had been treated with oral or parenteral

Results

Amongst the total of 329 patients presenting with clinically infected DFU in the repository, 36 subjects were “antibiotic naïve” and 293 patients were “prior antibiotic treated” patients. The data for 71 patients out of the 293 “prior antibiotic treated patients” were excluded from analysis because of incomplete follow-up or unavailability of prior antibiotic records. The baseline data for the 222 included patients are shown in Table 1. PVD was noticed in 23.2% of patients and all of them had

Discussion

We observed that prior antibiotic treated clinically infected DFU have mono-microbial isolates on tissue culture. Most of these patients were previously treated empirically with multiple courses of antibiotics without prior tissue culture and antimicrobial sensitivity analysis. P. aeruginosa and Acinetobacter sp. were the two most common isolated pathogens from tissue samples amongst these subjects. Resistance to commonly prescribed antibiotics for infected DFU particularly quinolones

Conclusion

Patients treated with antibiotics without prior tissue culture and anti-microbial sensitivity have predominantly mono-microbial and multi-drug resistant infections including Pseudomonas aeruginosa and Acinetobacter sp. The choice of empirical antibiotics should be guided by proper documentation of microbial profile and anti-microbial sensitivity in patients with clinically infected DFU until the definitive antibiotics could be administered based on culture reports. Quinolone resistance amongst

Acknowledgement

None.

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  • Cited by (0)

    Author disclosure statement: Nothing to disclose.

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